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<journal-id journal-id-type="publisher-id">Front. Sustain. Food Syst.</journal-id>
<journal-title>Frontiers in Sustainable Food Systems</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Sustain. Food Syst.</abbrev-journal-title>
<issn pub-type="epub">2571-581X</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fsufs.2024.1363994</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Sustainable Food Systems</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>The carbon footprint of livestock farms under conventional management and silvopastoral systems in Jalisco, Chiapas, and Campeche (Mexico)</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" corresp="yes">
<name><surname>Andrade</surname> <given-names>Hern&#x00E1;n J.</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="corresp" rid="c001"><sup>&#x002A;</sup></xref>
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<contrib contrib-type="author">
<name><surname>Vega</surname> <given-names>Andr&#x00E9;s</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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<contrib contrib-type="author">
<name><surname>Mart&#x00ED;nez-Salinas</surname> <given-names>Alejandra</given-names></name>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
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<contrib contrib-type="author">
<name><surname>Villanueva</surname> <given-names>Crist&#x00F3;bal</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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<contrib contrib-type="author">
<name><surname>Jim&#x00E9;nez-Trujillo</surname> <given-names>Jos&#x00E9; Antonio</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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<contrib contrib-type="author">
<name><surname>Betanzos-Simon</surname> <given-names>Juan Edduardo</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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<name><surname>P&#x00E9;rez</surname> <given-names>Edwin</given-names></name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
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<name><surname>Ibrahim</surname> <given-names>Muhammad</given-names></name>
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<contrib contrib-type="author">
<name><surname>Sep&#x00FA;lveda L</surname> <given-names>Claudia J.</given-names></name>
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<aff id="aff1"><sup>1</sup><institution>L&#x00ED;der Grupo de Investigaci&#x00F3;n PROECUT, Facultad de Ingenier&#x00ED;a Agron&#x00F3;mica, Universidad del Tolima</institution>, <addr-line>Ibagu&#x00E9;</addr-line>, <country>Colombia</country></aff>
<aff id="aff2"><sup>2</sup><institution>Livestock and Environmental Management Unit, The Tropical Agricultural Research and Higher Education Center (CATIE)</institution>, <addr-line>Turrialba</addr-line>, <country>Costa Rica</country></aff>
<aff id="aff3"><sup>3</sup><institution>Forest and Biodiversity in Productive Landscapes, The Tropical Agricultural Research and Higher Education Center (CATIE)</institution>, <addr-line>Turrialba</addr-line>, <country>Costa Rica</country></aff>
<author-notes>
<fn fn-type="edited-by" id="fn0001">
<p>Edited by: Alexandra Jacquelyn Burgess, University of Nottingham, United Kingdom</p>
</fn>
<fn fn-type="edited-by" id="fn0002">
<p>Reviewed by: Azam Lashkari, John Innes Centre, United Kingdom</p>
<p>Simon Moakes, Aberystwyth University, United Kingdom</p>
</fn>
<corresp id="c001">&#x002A;Correspondence: Hern&#x00E1;n J. Andrade, <email>hjandrade@ut.edu.co</email></corresp>
</author-notes>
<pub-date pub-type="epub">
<day>24</day>
<month>05</month>
<year>2024</year>
</pub-date>
<pub-date pub-type="collection">
<year>2024</year>
</pub-date>
<volume>8</volume>
<elocation-id>1363994</elocation-id>
<history>
<date date-type="received">
<day>31</day>
<month>12</month>
<year>2023</year>
</date>
<date date-type="accepted">
<day>07</day>
<month>05</month>
<year>2024</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x00A9; 2024 Andrade, Vega, Mart&#x00ED;nez-Salinas, Villanueva, Jim&#x00E9;nez-Trujillo, Betanzos-Simon, P&#x00E9;rez, Ibrahim and Sep&#x00FA;lveda Lopez.</copyright-statement>
<copyright-year>2024</copyright-year>
<copyright-holder>Andrade, Vega, Mart&#x00ED;nez-Salinas, Villanueva, Jim&#x00E9;nez-Trujillo, Betanzos-Simon, P&#x00E9;rez, Ibrahim and Sep&#x00FA;lveda Lopez</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p>
</license>
</permissions>
<abstract>
<p>Livestock production is one of the most important agricultural sources of greenhouses gasses (GHG). Transforming the livestock sector is a critical task to mitigate the effects of climate change, and the implementation of silvopastoral systems (SPS) may be a way to do so. Carbon footprint (CF) estimation was carried out for 131 conventional livestock farms (CONF) and SPS farms (SPSF) selected in the states of Jalisco, Chiapas and Campeche (Mexico). GHG emissions were estimated based on interviews with the farmers and farm monitoring to collect information about management, milk production and the live weight gain (LWG) of calves (for meat production) using national emission factors. Emissions from animals, fossil fuels, electricity and nitrogen fertilizers were estimated using Tier I and II criteria. Land use distribution was recorded for each farm, and their carbon fixation in total biomass and soils was estimated using studies from tropical Latin America. CF was estimated for area and for production of milk and the LWG of calves. SPSF had lower GHG emissions, higher carbon fixation rates and a better CF than CONF (5.7 vs. 8.0&#x2009;t CO<sub>2</sub>e/ha/year; 6.9 vs. 5.5&#x2009;t C/ha/year and&#x2009;&#x2212;&#x2009;5.0 vs. &#x2212;2.9&#x2009;t CO<sub>2</sub>e/ha/year, respectively). The CF of milk production and calf LWG were&#x2009;&#x2212;&#x2009;68.6 to &#x2212;4.6&#x2009;kg CO<sub>2</sub>e/kg and&#x2009;&#x2212;&#x2009;3.2 to &#x2212;0.1&#x2009;t CO<sub>2</sub>e/kg, respectively. Our results highlight the importance of implementing SPS to mitigate climate change in livestock production, given its contribution to GHG emissions and the importance of capturing atmospheric carbon in biomass and soils. National and regional policies should focus on promoting implementing SPS as an active and effective strategy for improving CF in livestock farms.</p>
</abstract>
<kwd-group>
<kwd>biomass</kwd>
<kwd>greenhouse gasses</kwd>
<kwd>mitigation</kwd>
<kwd>land use systems</kwd>
<kwd>carbon capture</kwd>
</kwd-group>
<counts>
<fig-count count="6"/>
<table-count count="1"/>
<equation-count count="5"/>
<ref-count count="75"/>
<page-count count="12"/>
<word-count count="8754"/>
</counts>
<custom-meta-wrap>
<custom-meta>
<meta-name>section-at-acceptance</meta-name>
<meta-value>Climate-Smart Food Systems</meta-value>
</custom-meta>
</custom-meta-wrap>
</article-meta>
</front>
<body>
<sec sec-type="intro" id="sec1">
<label>1</label>
<title>Introduction</title>
<p>Livestock activity contributes between 12 and 14.5% of anthropogenic greenhouse gas (GHG) emissions, with milk and meat production responsible for 3&#x2013;4% (<xref ref-type="bibr" rid="ref70">Velarde-Guill&#x00E9;n et al., 2022</xref>) and 11&#x2013;12%, respectively (<xref ref-type="bibr" rid="ref32">Grain, 2017</xref>). Methane (CH<sub>4</sub>) is the major contributor to these emissions, but with a wide range, from 34 to 86% (<xref ref-type="bibr" rid="ref25">Gerber et al., 2013</xref>; <xref ref-type="bibr" rid="ref56">Rice et al., 2017</xref>; <xref ref-type="bibr" rid="ref44">Mazzetto et al., 2020</xref>; <xref ref-type="bibr" rid="ref31">Gonz&#x00E1;lez-Quintero et al., 2021</xref>; <xref ref-type="bibr" rid="ref34">Hawkins et al., 2021</xref>), with some researchers finding rates of more than 70%. Mexico is the 12th biggest emitter of CO<sub>2</sub> in the world (<xref ref-type="bibr" rid="ref40">International Energy Agency [IEA], 2020</xref>) and accounts for 1% of global GHG emissions (<xref ref-type="bibr" rid="ref73">He et al., 2021</xref>). The agricultural sector in Mexico emitted 92 Tg CO<sub>2</sub>e to which livestock contributed close to 50% (<xref ref-type="bibr" rid="ref55">Prospero-Bernal et al., 2019</xref>). Mexico has proposed a reduction of 22% by 2030, with a target of 8% for the livestock sector (<xref ref-type="bibr" rid="ref36">Instituto Nacional de ecolog&#x00ED;a y Cambio Clim&#x00E1;tico [INECC], 2018</xref>). The most recent <xref ref-type="bibr" rid="ref36">Instituto Nacional de ecolog&#x00ED;a y Cambio Clim&#x00E1;tico [INECC], (2018)</xref> estimated 683 Tg CO<sub>2</sub>e the emissions to which livestock contributed 10.3%; this makes livestock production the second most important contributor to GHG emissions after the energy sector (70% of the national total). In the livestock sector, enteric fermentation is the main source of emissions (76%), followed by manure management (24%) (<xref ref-type="bibr" rid="ref36">Instituto Nacional de ecolog&#x00ED;a y Cambio Clim&#x00E1;tico [INECC], 2018</xref>).</p>
<p>Worldwide, the demand for livestock production, as well as its derivatives such as milk and cheese, has increased in recent decades as a result of increases in population and consumption preferences (<xref ref-type="bibr" rid="ref26">Ghosh et al., 2020</xref>; <xref ref-type="bibr" rid="ref48">Navarrete, 2020</xref>). In 1950, Mexico had a population of 25.8 million people; 70&#x2009;years later, Mexico&#x2019;s population has almost quintupled (126 million). It is estimated that, by 2050, Mexico&#x2019;s population will reach 148.2 million (<xref ref-type="bibr" rid="ref28">de M&#x00E9;xico, 2018</xref>). Cattle ranching is the most widespread productive activity in rural areas of Mexico and is carried out in all agroecological regions on about 110 million hectares (60% of the territory), with about 28.4 million head of cattle. Production ranges from highly innovative and integrated systems, to more traditional approaches (<xref ref-type="bibr" rid="ref53">Pagiola et al., 2004</xref>; <xref ref-type="bibr" rid="ref37">Instituto Nacional de Estad&#x00ED;stica y Geograf&#x00ED;a [INEGI], 2016</xref>). Traditional cattle farms are based on extensive grazing with or without supplementation and practices to improve livestock management, without considering the effect on environment. More technologically oriented systems usually use silvopastoral systems (SPS), take records and apply good farming practices.</p>
<p>Carbon footprint (CF) estimation has become necessary for livestock farming and management strategies in light of climate change (<xref ref-type="bibr" rid="ref46">Molina-Rivera et al., 2019</xref>; <xref ref-type="bibr" rid="ref3">Ali et al., 2020</xref>; <xref ref-type="bibr" rid="ref22">Elshimy and El-Aasar, 2020</xref>; <xref ref-type="bibr" rid="ref26">Ghosh et al., 2020</xref>; <xref ref-type="bibr" rid="ref60">Secretar&#x00ED;a de Medio Ambiente y Recursos Naturales [SEMARNAT], 2020</xref>). Numerous strategies have been applied to mitigate the emissions caused by livestock production, such as carbon capture and conservation in tree-dominated land uses such as forests and SPS (<xref ref-type="bibr" rid="ref4">Andrade et al., 2008</xref>; <xref ref-type="bibr" rid="ref46">Molina-Rivera et al., 2019</xref>). Improving a farm&#x2019;s CF can also occur by improving animal feeding through the use of a higher quality diet and improved genetics, having more productive animals (<xref ref-type="bibr" rid="ref46">Molina-Rivera et al., 2019</xref>; <xref ref-type="bibr" rid="ref55">Prospero-Bernal et al., 2019</xref>). Establishing SPS on conventional open pastures increases the capture of carbon in biomass and soils, as well as reducing deforestation and GHG emissions (<xref ref-type="bibr" rid="ref4">Andrade et al., 2008</xref>; <xref ref-type="bibr" rid="ref9">Aryal et al., 2022</xref>; <xref ref-type="bibr" rid="ref50">Oldfield et al., 2022</xref>; <xref ref-type="bibr" rid="ref67">Udawatta et al., 2022</xref>). Several studies have confirmed the positive effect of SPS in reducing the CF of livestock farms (<xref ref-type="bibr" rid="ref58">Schettini et al., 2021</xref>; <xref ref-type="bibr" rid="ref13">Brook et al., 2022</xref>; <xref ref-type="bibr" rid="ref54">Parra et al., 2022</xref>).</p>
<p>The project &#x201C;Promoting biodiversity conservation through climate-smart agrosilvopastoral practices in livestock-dominated landscapes in three regions of Mexico&#x201D; (Biodiversidad y Paisajes Ganaderos Agrosilvopastoriles Sostenibles; i.e. BioPaSOS started in 2017) in the states of Jalisco, Chiapas and Campeche (Mexico); one of the main purposes of this project was to help reduce GHG emissions by promoting the implementation of SPS across livestock farms. The goal of the present work is to estimate the CF of livestock farms with conventional systems (CONF) and those using SPS (SPSF) in these three states and to identify the most important components of their CF. The results will provide a guideline for the formulation of policies and strategies for technology transfer and adoption to make livestock systems more environmentally friendly to mitigate climate change.</p>
</sec>
<sec sec-type="methods" id="sec2">
<label>2</label>
<title>Methods</title>
<sec id="sec3">
<label>2.1</label>
<title>Study area</title>
<p>This study was carried out in the states of Jalisco, Chiapas and Campeche in Mexico. The main characteristics (i.e., biophysical conditions and management) of the three states are described in <xref ref-type="bibr" rid="ref9">Aryal et al. (2022)</xref>. The states included in the research were selected &#x2013; with the support of the national, state and local Secretary of Livestock and Environment &#x2013; according to the following criteria: (1) deforestation problems, (2) areas with pastures for livestock, (3) problems with forest fires and erosion and (4) priority areas for conservation.</p>
<p>Jalisco is located in the temperate region at 20&#x00B0;34&#x2032;00&#x2033;N and 103&#x00B0;40&#x2032;35&#x2033;W (<xref ref-type="bibr" rid="ref11">Bautista et al., 2020</xref>), where forests, grasslands, shrublands and agriculture can be found in a transition zone between the Nearctic and Neotropical regions (<xref ref-type="fig" rid="fig1">Figure 1</xref>). The average annual rainfall is 862&#x2009;mm, with an average of 11.19&#x2009;days of frost per year. The average temperature in the dry season is 30&#x00B0;C and 12&#x00B0;C in the rainy season. These factors are key to the development of productive activities, especially cattle (<xref ref-type="bibr" rid="ref27">de Jalisco, 2011</xref>). The total cattle population of the state is 3,409,172 heads (71 and 29% for meat and milk production, respectively) (<xref ref-type="bibr" rid="ref49">OEIDRUS-Jalisco, 2017</xref>). Livestock is the main source of income for most families, and there is a mean animal stocking rate of 0.76&#x2009;AU/ha foraging grasses, shrubs and trees (<xref ref-type="bibr" rid="ref59">S&#x00E1;nchez-Romero et al., 2022</xref>). In 2015, Jalisco produced 2.2 million L of milk a day and 216,535 t of meat each year (<xref ref-type="bibr" rid="ref49">OEIDRUS-Jalisco, 2017</xref>).</p>
<fig position="float" id="fig1">
<label>Figure 1</label>
<caption>
<p>Location of BioPaSOS project states in Mexico.</p>
</caption>
<graphic xlink:href="fsufs-08-1363994-g001.tif"/>
</fig>
<p>Chiapas is located in the intertropical zone (16&#x00B0;24&#x2032;36&#x2033;N and 92&#x00B0;24&#x2032;31&#x2033;W) with a humid tropical climate (<xref ref-type="bibr" rid="ref11">Bautista et al., 2020</xref>) (<xref ref-type="fig" rid="fig1">Figure 1</xref>). The annual rainfall in coastal areas reaches 4,000&#x2009;mm, while in central areas, the rainfall is less than 1,000&#x2009;mm; the average altitude is 320&#x2009;m. In some places, the average temperature is above 23&#x00B0;C and in other places the temperature falls below 15&#x00B0;C. Chiapas has 12,025&#x2009;km<sup>2</sup> of primary forests, 16,643&#x2009;km<sup>2</sup> of cropland and 19,518&#x2009;km<sup>2</sup> of cultivated or induced pastures dedicated to livestock, which have increased in area at an average rate of 345.7&#x2009;km<sup>2</sup> each year (<xref ref-type="bibr" rid="ref30">Gobierno del Estado de Chiapas, 2019</xref>). Chiapas has 2.7 million head of cattle and is the third biggest producer of meat in Mexico (217,395&#x2009;t/year) (<xref ref-type="bibr" rid="ref62">Servicio de Informaci&#x00F3;n Agroalimentaria y Pesquera [SIAP], 2016</xref>), mainly in dual purpose systems (<xref ref-type="bibr" rid="ref43">Mart&#x00ED;nez-Garc&#x00ED;a et al., 2012</xref>).</p>
<p>Campeche is located in the tropical region (18&#x00B0;50&#x2032;11&#x2033;N and 90&#x00B0;24&#x2032;12&#x2033;0) (<xref ref-type="bibr" rid="ref11">Bautista et al., 2020</xref>) (<xref ref-type="fig" rid="fig1">Figure 1</xref>). The state covers 57,924&#x2009;km<sup>2</sup> with 11 municipalities that represent 3% of the country. It is primarily made up of sub-horizontal plains (41%) and hilly areas (35%). The average annual temperature is approximately 26&#x00B0;C, with a mean annual rainfall of 1,272&#x2009;mm. The area is dominated by secondary vegetation (54%), forests (16%) and grasslands (13%), as well as, to a lesser extent, by agriculture, forest, water bodies, areas without vegetation and urban areas (<xref ref-type="bibr" rid="ref12">Biodiversidad y Paisajes Ganaderos Agrosilvopastoriles Sostenibles [BioPaSOS]. (s.f.), 2017</xref>). The livestock sector covers 58% of agricultural production in Campeche (<xref ref-type="bibr" rid="ref29">Gobierno del Estado de Campeche, 2015</xref>), with a total of 650,000 head of cattle (<xref ref-type="bibr" rid="ref62">Servicio de Informaci&#x00F3;n Agroalimentaria y Pesquera [SIAP], 2016</xref>).</p>
</sec>
<sec id="sec4">
<label>2.2</label>
<title>Farm selection</title>
<p>The sample included 131 livestock farms. In each state, a meeting was held with producers interested in participating in the BioPaSOS project, from which a list was drawn up and approved by the local authorities of each Ejido.</p>
<p>Farms were classified either as conventional (CONF) or SPS farms (SPSF). CONF practice extensive grazing, with or without supplementation, and implement practices or technologies to improve livestock productivity only, without considering the effect on the environment. SPSF implement SPS production systems, including dispersed trees in native or improved pastures, fodder banks and multi-stratum live fences. These farms also engage in good livestock practices, such as pasture rotation, management of feed records, vaccination, deworming and production, as well as rational use of veterinary products and supplemental feeding with silage and multi-nutritional blocks. Farmers with SPSF were selected to participate in the BioPaSOS project based on the following criteria: (1) be an initiated sustainable livestock producer, (2) innovative (creative), (3) recognized in the community, (4) participatory, (5) interested in learning, (6) availability of time and (7) willingness to experiment (participatory research). Farmers with CONF were randomly selected from among those that were not participating in the BioPaSOS project.</p>
<p>Out of the total of 131 farms, 70 were visited only once, 40 in Chiapas and 30 in Campeche. The remaining farms were visited once a month for 12 consecutive months (11, 40 and 10 in Jalisco, Chiapas and Campeche, respectively). A semi-structured interview was applied to those farms that were visited once. Records of information, such as milk production and live weight per cow, by weighing milk and animals with scales, were carried out for two farms per state for two days during each monitoring period.</p>
</sec>
<sec id="sec5">
<label>2.3</label>
<title>Variables measured</title>
<p>Data were collected on the most relevant variables for estimating GHG emissions, such as geographic area (applied geographic scope, climate and soil), land use distribution, milk production and quality, cattle characteristics (breed and number and weight of animals), stocking rate, pastures and supplements used, as well as their nutritional characteristics (digestibility, crude protein, neutral detergent fiber and metabolizable energy of supplements) and dry matter consumption per animal. We also inquired about production costs, electrical energy used on the farm, use of nitrogen fertilizers, use of fossil fuels and firewood and manure applied in the different land uses, fuel used on and off the farm and percentage of digestibility intake. Ym, which quantifies enteric CH<sub>4</sub> emissions based on gross energy intake, and country-specific emission factors were used for these estimations.</p>
</sec>
<sec id="sec6">
<label>2.4</label>
<title>GHG emissions analysis</title>
<p>The data collected were organized and analyzed to estimate the total emissions generated by identified production systems and farms (t CO<sub>2</sub>e/ha/year and t CO<sub>2</sub>e/farm/year) and on a unit basis per animal unit (t CO<sub>2</sub>e/UA/year) or per product unit (kg CO<sub>2</sub>e/kg milk and t CO<sub>2</sub>e/kg meat of calves sold). GHG emissions were estimated with a local calculation tool (GEI-CATIE Tool) (<xref ref-type="bibr" rid="ref69">Vega, 2016</xref>) at an animal scale; this is a tool generated by CATIE researchers in a spreadsheet for making GHG estimates in livestock systems. It contemplates Tiers I and II, according to the availability of activity data for the region studied and following the <xref ref-type="bibr" rid="ref38">Intergovernmental Panel on Climate Change [IPCC] (2006)</xref> guidelines. Tier I is a basic method for estimating GHG emissions, using default emission factors and simple national activity data. It is generally less precise and is used when detailed country-specific data are unavailable. Tier II involves more detailed approaches for estimating emissions, utilizing country-or region-specific emissions factors and more comprehensive activity data. It provides more accurate estimates than Tier I and is applied when more detailed data are available.</p>
<p>Emissions were considered in two phases. Phase 1, on-farm emissions, includes data from enteric fermentation, manure management, use of nitrogen fertilizers, use of fossil fuels and electricity consumption. Phase 2, off-farm emissions, includes data from use of fossil fuels in the purchase of inputs, transportation of labor and marketing of products and emissions from production processes in the manufacture of inputs (gas).</p>
<p>The following emissions factors were used: 0.01&#x2009;kg&#x2009;N&#x2082;O/kg&#x2009;N (<xref ref-type="bibr" rid="ref38">Intergovernmental Panel on Climate Change [IPCC], 2006</xref>) for nitrogen fertilization; 2.596 and 2.322&#x2009;kg CO&#x2082;e/l for diesel and gasoline, respectively (<xref ref-type="bibr" rid="ref35">Instituto Nacional de ecolog&#x00ED;a y Cambio Clim&#x00E1;tico [INECC], 2014</xref>; <xref ref-type="bibr" rid="ref61">Secretar&#x00ED;a de Medio Ambiente y Recursos Naturales [SEMARNAT], 2021a</xref>); and 0.494&#x2009;t CO&#x2082;e/MWh for electricity (<xref ref-type="bibr" rid="ref001">Secretar&#x00ED;a de Medio Ambiente y Recursos Naturales [SEMARNAT], 2021b</xref>). These calculations were developed following <xref ref-type="disp-formula" rid="EQ1">Eq. (1)</xref>.</p>
<disp-formula id="EQ1">
<label>(1)</label>
<mml:math id="M1">
<mml:mi>G</mml:mi>
<mml:mi>H</mml:mi>
<mml:mi>G</mml:mi>
<mml:mspace width="0.25em"/>
<mml:mi mathvariant="italic">emissions</mml:mi>
<mml:mo>=</mml:mo>
<mml:mi mathvariant="italic">Activity</mml:mi>
<mml:mspace width="0.25em"/>
<mml:mi mathvariant="italic">data</mml:mi>
<mml:mo>&#x2217;</mml:mo>
<mml:mi mathvariant="italic">Emissions</mml:mi>
<mml:mspace width="0.25em"/>
<mml:mi mathvariant="italic">factor</mml:mi>
</mml:math>
</disp-formula>
<p>Where:</p>
<p>GHG emissions: <italic>t</italic> CO<sub>2</sub>e/year/farm.</p>
<p>Activity data: Number of animals/ha or quantity of inputs (e.g., kWh/month/farm).</p>
<p>Emissions factor: GHG emissions by unit of animal or input (e.g. g CO<sub>2</sub>e/kWh of electricity).</p>
</sec>
<sec id="sec7">
<label>2.5</label>
<title>Estimation of carbon sequestration in total biomass and soils</title>
<p>Information about land use distribution in each livestock farm was collected via surveys and monitoring visits. Specifically, data about area and characteristics of land uses were acquired from farmers. A literature review was also conducted to determine the carbon fixation rates of the biomass and soils of land uses present across selected farms (<xref ref-type="table" rid="tab1">Table 1</xref>). Based on this information, the total carbon fixation rate for each farm was estimated (<xref ref-type="disp-formula" rid="EQ2">Eq. 2</xref>).</p>
<disp-formula id="EQ2">
<label>(2)</label>
<mml:math id="M2">
<mml:mi>C</mml:mi>
<mml:mi>C</mml:mi>
<mml:mo>=</mml:mo>
<mml:mo stretchy="true">&#x2211;</mml:mo>
<mml:mrow>
<mml:mfenced open="(" close=")">
<mml:mrow>
<mml:mi mathvariant="italic">CCRi</mml:mi>
<mml:mo>&#x2217;</mml:mo>
<mml:mi mathvariant="italic">Ai</mml:mi>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:math>
</disp-formula>
<p>Where:</p>
<table-wrap position="float" id="tab1">
<label>Table 1</label>
<caption>
<p>Carbon fixation rates in total biomass and soils of land use systems estimated in some Latin-American countries in the tropics.</p>
</caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th align="left" valign="top">Land use</th>
<th align="center" valign="top">Fixation rate (t C /ha/year)</th>
<th align="left" valign="top">Country</th>
<th align="left" valign="top">Source</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle">Degraded pastures</td>
<td align="center" valign="middle">&#x2212;0.28</td>
<td align="left" valign="middle">Costa Rica and Brazil</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref17">Centro Agron&#x00F3;mico Tropical de Investigaci&#x00F3;n y Ense&#x00F1;anza [CATIE] (2010)</xref>, <xref ref-type="bibr" rid="ref18">de Figueiredo et al. (2016)</xref>.</td>
</tr>
<tr>
<td align="left" valign="middle">Natural pastures with no trees</td>
<td align="center" valign="middle">0.32</td>
<td align="left" valign="middle">M&#x00E9;xico, Costa Rica, Honduras and Nicaragua</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref72">Villanueva-L&#x00F3;pez et al. (2015)</xref>, <xref ref-type="bibr" rid="ref42">L&#x00F3;pez-Santiago et al. (2019)</xref>, <xref ref-type="bibr" rid="ref47">Nahed-Toral et al. (2013)</xref>, <xref ref-type="bibr" rid="ref4">Andrade et al. (2008)</xref>, <xref ref-type="bibr" rid="ref15">Canu et al. (2018)</xref>, <xref ref-type="bibr" rid="ref63">Tobar et al. (2018)</xref>.</td>
</tr>
<tr>
<td align="left" valign="middle">Natural pastures with trees</td>
<td align="center" valign="middle">1.17</td>
<td align="left" valign="middle">Costa Rica, Honduras and Nicaragua</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref17">Centro Agron&#x00F3;mico Tropical de Investigaci&#x00F3;n y Ense&#x00F1;anza [CATIE] (2010)</xref>, <xref ref-type="bibr" rid="ref4">Andrade et al. (2008)</xref>, <xref ref-type="bibr" rid="ref15">Canu et al. (2018)</xref>, <xref ref-type="bibr" rid="ref63">Tobar et al. (2018)</xref>.</td>
</tr>
<tr>
<td align="left" valign="middle">Improved pastures with no trees</td>
<td align="center" valign="middle">0.49</td>
<td align="left" valign="middle">Costa Rica, Honduras and Nicaragua</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref17">Centro Agron&#x00F3;mico Tropical de Investigaci&#x00F3;n y Ense&#x00F1;anza [CATIE] (2010)</xref>, <xref ref-type="bibr" rid="ref4">Andrade et al. (2008)</xref>, <xref ref-type="bibr" rid="ref15">Canu et al. (2018)</xref>, <xref ref-type="bibr" rid="ref63">Tobar et al. (2018)</xref></td>
</tr>
<tr>
<td align="left" valign="middle">Improved pastures with low tree density</td>
<td align="center" valign="middle">0.91</td>
<td align="left" valign="middle">Costa Rica</td>
<td align="left" valign="middle">
<xref ref-type="bibr" rid="ref17">Centro Agron&#x00F3;mico Tropical de Investigaci&#x00F3;n y Ense&#x00F1;anza [CATIE] (2010)</xref>
</td>
</tr>
<tr>
<td align="left" valign="middle">Improved pastures with high tree density</td>
<td align="center" valign="middle">1.34</td>
<td align="left" valign="middle">Costa Rica</td>
<td align="left" valign="middle">
<xref ref-type="bibr" rid="ref17">Centro Agron&#x00F3;mico Tropical de Investigaci&#x00F3;n y Ense&#x00F1;anza [CATIE] (2010)</xref>
</td>
</tr>
<tr>
<td align="left" valign="middle">Grass forage banks</td>
<td align="center" valign="middle">0.27</td>
<td align="left" valign="middle">Costa Rica, Honduras and Nicaragua</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref4">Andrade et al. (2008)</xref>; <xref ref-type="bibr" rid="ref15">Canu et al. (2018)</xref>; <xref ref-type="bibr" rid="ref63">Tobar et al. (2018)</xref></td>
</tr>
<tr>
<td align="left" valign="middle">Woody forage banks</td>
<td align="center" valign="middle">3.00</td>
<td align="left" valign="middle">M&#x00E9;xico, Honduras and Nicaragua</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref42">L&#x00F3;pez-Santiago et al. (2019)</xref>, <xref ref-type="bibr" rid="ref15">Canu et al. (2018)</xref>, <xref ref-type="bibr" rid="ref63">Tobar et al. (2018)</xref>.</td>
</tr>
<tr>
<td align="left" valign="middle">Permanent crops</td>
<td align="center" valign="middle">2.60</td>
<td align="left" valign="middle">Costa Rica and Colombia</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref51">Ortiz and Riascos (2006)</xref>, <xref ref-type="bibr" rid="ref6">Andrade et al. (2014a)</xref>, <xref ref-type="bibr" rid="ref45">Mena and Andrade (2021)</xref>.</td>
</tr>
<tr>
<td align="left" valign="middle">Forest plantations</td>
<td align="center" valign="middle">3.21</td>
<td align="left" valign="middle">Costa Rica</td>
<td align="left" valign="middle">
<xref ref-type="bibr" rid="ref17">Centro Agron&#x00F3;mico Tropical de Investigaci&#x00F3;n y Ense&#x00F1;anza [CATIE] (2010)</xref>
</td>
</tr>
<tr>
<td align="left" valign="middle">Secondary forests</td>
<td align="center" valign="middle">3.20</td>
<td align="left" valign="middle">Colombia and Costa Rica</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref45">Mena and Andrade (2021)</xref>, <xref ref-type="bibr" rid="ref17">Centro Agron&#x00F3;mico Tropical de Investigaci&#x00F3;n y Ense&#x00F1;anza [CATIE] (2010)</xref>, <xref ref-type="bibr" rid="ref23">Fonseca et al. (2011)</xref>.</td>
</tr>
<tr>
<td align="left" valign="middle">Multistratum live fences</td>
<td align="center" valign="middle">4.10</td>
<td align="left" valign="middle">M&#x00E9;xico, Honduras and Nicaragua</td>
<td align="left" valign="middle"><xref ref-type="bibr" rid="ref72">Villanueva-L&#x00F3;pez et al. (2015)</xref>, <xref ref-type="bibr" rid="ref15">Canu et al. (2018)</xref>, <xref ref-type="bibr" rid="ref63">Tobar et al. (2018)</xref>.</td>
</tr>
</tbody>
</table>
</table-wrap>
<p>CC: Carbon capture per farm (<italic>t</italic> CO<sub>2</sub>e/farm/year).</p>
<p>CCRi: Carbon capture rate by land use (<italic>t</italic> CO<sub>2</sub>e/ha/year).</p>
<p>Ai: Area of each land use (ha).</p>
</sec>
<sec id="sec8">
<label>2.6</label>
<title>Carbon footprint of farms</title>
<p>The CF was estimated as the difference between the carbon fixation rate in biomass and soils and the GHG emissions of each farm (<xref ref-type="disp-formula" rid="EQ3">Eq. 3</xref>). Likewise, the CF per unit of animal, milk production and calf LWG was estimated dividing CF by the animal stocking rate, milk production and calf LWG (<xref ref-type="disp-formula" rid="EQ4">Eq. 4</xref>). Information about milk production and meat sales was gathered from farmers. Total CF in dual purpose farms was divided by milk production and calf LWG employing the allocation factor recommended by <xref ref-type="bibr" rid="ref64">Thoma et al. (2013)</xref> (<xref ref-type="disp-formula" rid="EQ5">Eq. 5</xref>). The GHG equivalency factors, recommended by <xref ref-type="bibr" rid="ref39">Intergovernmental Panel on Climate Change [IPCC] (2013)</xref>, were used: 1&#x2009;kg CH<sub>4</sub>&#x2009;=&#x2009;28&#x2009;kg CO<sub>2</sub>e and 1&#x2009;kg N<sub>2</sub>O&#x2009;=&#x2009;265&#x2009;kg CO<sub>2</sub>e.</p>
<disp-formula id="EQ3">
<label>(3)</label>
<mml:math id="M3">
<mml:mi>C</mml:mi>
<mml:mi>F</mml:mi>
<mml:mo>=</mml:mo>
<mml:mi mathvariant="italic">GHGe</mml:mi>
<mml:mo>&#x2212;</mml:mo>
<mml:mi>C</mml:mi>
<mml:mi>C</mml:mi>
</mml:math>
</disp-formula>
<p>Where:</p>
<p>CF: Carbon footprint per farm (t CO<sub>2</sub>e/farm/year).</p>
<p>GHGe: Greenhouse gas emissions per farm (t CO<sub>2</sub>e/farm/year).</p>
<p>CC: Carbon capture per farm (t CO<sub>2</sub>e/farm/year)</p>
<disp-formula id="EQ4">
<label>(4)</label>
<mml:math id="M4">
<mml:mi>C</mml:mi>
<mml:mi>F</mml:mi>
<mml:mi>u</mml:mi>
<mml:mo>=</mml:mo>
<mml:mfrac>
<mml:mrow>
<mml:mi>C</mml:mi>
<mml:mi>F</mml:mi>
</mml:mrow>
<mml:mi mathvariant="italic">Quantity</mml:mi>
</mml:mfrac>
</mml:math>
</disp-formula>
<p>Where:</p>
<p>CFu: Unitary carbon footprint (e.g., t CO<sub>2</sub>e/UA/year or kg CO<sub>2</sub>e/kg of milk).</p>
<p>CF: Carbon footprint per farm (t CO<sub>2</sub>e/farm/year).</p>
<p>Quantity: Quantity of animals, milk production or calf LWG (e.g., UA/farm or kg milk/year/farm)</p>
<disp-formula id="EQ5">
<label>(5)</label>
<mml:math id="M5">
<mml:mi mathvariant="italic">AFmilk</mml:mi>
<mml:mo>=</mml:mo>
<mml:mn>1</mml:mn>
<mml:mo>&#x2212;</mml:mo>
<mml:mn>6.04</mml:mn>
<mml:mo>&#x2217;</mml:mo>
<mml:mi>B</mml:mi>
<mml:mi>M</mml:mi>
<mml:mi>R</mml:mi>
</mml:math>
</disp-formula>
<p>Where:</p>
<p>AFmilk: Allocation factor for milk production.</p>
<p>BMR: Ratio of production of milk corrected/live weight of animals sold.</p>
</sec>
<sec id="sec9">
<label>2.7</label>
<title>Statistical analysis</title>
<p>The data were analyzed with descriptive statistics and scatter graphs to determine the relationships between GHG emissions, pasture area and total number of animals. Variance analyses were carried out to determine the behavior of GHG emissions and the CF for CONF and SPSF. The analyses were done using the software program Infostat, version 2019 (<xref ref-type="bibr" rid="ref20">Di Rienzo et al., 2019</xref>).</p>
</sec>
<sec id="sec10">
<label>2.8</label>
<title>Limits of the work</title>
<p>Emissions estimates were calculated following Tier I and Tier II criteria (<xref ref-type="bibr" rid="ref38">Intergovernmental Panel on Climate Change [IPCC], 2006</xref>) and using emissions factors specifically developed for Mexico (<xref ref-type="bibr" rid="ref35">Instituto Nacional de ecolog&#x00ED;a y Cambio Clim&#x00E1;tico [INECC], 2014</xref>; <xref ref-type="bibr" rid="ref61">Secretar&#x00ED;a de Medio Ambiente y Recursos Naturales [SEMARNAT], 2021a</xref>). Emissions from the use of nitrogen fertilizers, fossil fuels, electric energy and N<sub>2</sub>O emissions from solid and liquid waste management were estimated with Tier I. Emissions of CH<sub>4</sub> from the use of fossil fuels were estimated with Tier II. CH<sub>4</sub> emissions from enteric fermentation by livestock category and waste management from solid and liquid waste management were estimated with Tier II. The CF was estimated for the livestock production of farms, including fossil fuels for inputs, as well as labor and product transportation.</p>
</sec>
</sec>
<sec sec-type="results" id="sec11">
<label>3</label>
<title>Results</title>
<sec id="sec12">
<label>3.1</label>
<title>GHG emissions</title>
<p>Increasing the forage area reduced GHG emissions (<xref ref-type="fig" rid="fig2">Figure 2A</xref>), while increasing the number of animals resulted in a quadratic trend in emissions &#x2013; that is, at a medium number of animals, emissions were maximized (<xref ref-type="fig" rid="fig2">Figure 2B</xref>). These trends did not seem to be affected by the type of production (CONF or SPSF) or by state (Jalisco, Chiapas or Campeche). Some atypical cases of GHG emissions were, however, observed for some farms that have management strategies differing from the traditional ones.</p>
<fig position="float" id="fig2">
<label>Figure 2</label>
<caption>
<p>Relationship between greenhouse gas (GHG) emissions and forage area <bold>(A)</bold> and total number of animals <bold>(B)</bold> in livestock farms with conventional (CONF) and silvopastoral systems (SPSF) in Jalisco, Chiapas and Campeche (Mexico).</p>
</caption>
<graphic xlink:href="fsufs-08-1363994-g002.tif"/>
</fig>
<p>CONF emitted a mean of 8.0&#x2009;t CO<sub>2</sub>e/ha/year, with higher values than those found for SPSF (5.7&#x2009;t CO<sub>2</sub>e/ha/year); use of SPS thus corresponded to a 16.5% reduction. However, the results differed by state. In Campeche and Jalisco, emissions were higher for CONF than for SPSF (2.0&#x2009;&#x00B1;&#x2009;0.2 vs. 1.5&#x2009;&#x00B1;&#x2009;0.2 and 4.3&#x2009;&#x00B1;&#x2009;2.2 vs. 1.9&#x2009;&#x00B1;&#x2009;0.4&#x2009;t CO<sub>2</sub>e/ha/year, respectively), but SPSF in Chiapas emitted more GHG than did CONF in that state (2.4&#x2009;&#x00B1;&#x2009;0.3 vs. 1.7&#x2009;&#x00B1;&#x2009;0.3&#x2009;t CO<sub>2</sub>e/ha/year, respectively) (<xref ref-type="fig" rid="fig3">Figure 3A</xref>). However, the differences in GHG emissions between states and between management types were not significant (<italic>p</italic>&#x2009;&#x003E;&#x2009;0.05). In Chiapas, emissions from animals, fertilizers and fuels were up to 70% higher in SPSF than in CONF.</p>
<fig position="float" id="fig3">
<label>Figure 3</label>
<caption>
<p>Greenhouse gas (GHG) emissions <bold>(A)</bold> and their distribution by components <bold>(B)</bold> in livestock conventional farms (CONF) and silvopastoral production farms (SPSF) in Campeche, Chiapas and Jalisco (Mexico). Error bars indicate standard error of the mean. Different lowercase letters indicate statistical differences (<italic>p</italic>&#x2009;&#x003C;&#x2009;0.05) between system types by each state. Different capital letters indicate statistical differences (p&#x2009;&#x003C;&#x2009;0.05) between states.</p>
</caption>
<graphic xlink:href="fsufs-08-1363994-g003.tif"/>
</fig>
<p>Animals contributed 98.0% of total GHG emissions, compared to nitrogen fertilizers, electricity and fossil fuels (1.5, 0.3 and 0.1%, respectively). Nitrogen fertilizers emitted twice as much GHG in CONF than in SPSF; that is, the use of tree production systems contributes to reducing emissions and costs by about 50%. Likewise, animals, fuel use and electrical energy emitted 1.4, 1.3 and 1.2 times more in CONF than in SPSF (<xref ref-type="fig" rid="fig3">Figure 3B</xref>). The average emissions from animals in SPSF in Campeche were 1.4&#x2009;t CO<sub>2</sub>e/ha/year, followed by 1.9 and 2.3&#x2009;t CO<sub>2</sub>e/ha/year in Jalisco and Chiapas, respectively. In contrast, animals in CONF in Chiapas had the lowest emissions (1.7&#x2009;t CO<sub>2</sub>e/ha/year) compared to Campeche and Jalisco, which emitted 2.0 and 4.3&#x2009;t CO<sub>2</sub>e/ha/year, respectively (<xref ref-type="fig" rid="fig3">Figure 3B</xref>).</p>
</sec>
<sec id="sec13">
<label>3.2</label>
<title>Carbon fixation rates</title>
<p>Degraded pastures in conventionally managed farms have a negative fixation rate of 0.7&#x2009;t C/farm/year &#x2013; that is, they have GHG emissions of about 2.6&#x2009;t CO<sub>2</sub>e/farm/year (<xref ref-type="fig" rid="fig4">Figure 4</xref>). This is the only land use system emitting GHGs on these farms &#x2013; that is, it is contributing to increasing atmospheric CO<sub>2</sub> concentrations. The average carbon fixation in CONF was 115.5&#x2009;t C/farm/year, which contrasts with the 87.5&#x2009;t C/farm/year for SPSF (5.5 vs. 6.9&#x2009;t C/ha/year, respectively); SPS are thus contributing to the reduction of emissions by 32% at the farm level and 24% per ha.</p>
<fig position="float" id="fig4">
<label>Figure 4</label>
<caption>
<p>Carbon sequestration rate in total biomass and soils by type of land use system in livestock farms with conventional (CONF) and silvopastoral systems (SPSF) in Campeche, Chiapas and Jalisco (Mexico). Error bars indicate standard error of the mean. DP: degraded pastures; NP: native pastures; IP: improved pastures; PT: pastures with trees; GFB: grass fodder banks; WFB: woody fodder banks; PC: perennial crops; FP: forest plantations; F: fallows (natural regeneration); RF: riparian forests; SF: secondary forests; MLF: multistrata live fences.</p>
</caption>
<graphic xlink:href="fsufs-08-1363994-g004.tif"/>
</fig>
<p>The highest carbon fixation rates in CONF were found in forest plantations (FP), fallows (F) and pastures with trees (PT), with an average of 8.6, 14.2 and 21.5&#x2009;t C/farm/year, respectively. In contrast, grass fodder banks (GFB), woody fodder banks (WFB) and riparian forests (RF) fix just 0.1, 0.2 and 1.3&#x2009;t C/farm/year, respectively. For SPSF, the highest carbon fixation rates were achieved in PT, F and secondary forests (SF), with 22.7, 26.9 and 42.4&#x2009;t C/farm/year, respectively (<xref ref-type="fig" rid="fig4">Figure 4</xref>). In Campeche, the average fixation rate was 87.5 vs. 171.5&#x2009;t C/farm/year in CONF and SPSF, respectively. The same trends appeared in Jalisco (45.3 vs. 150.5&#x2009;t C/farm/year for these systems), in contrast to the state of Chiapas, which reported just 60.0 and 43.9&#x2009;t C/farm/year for CONF and SPSF, respectively (<xref ref-type="fig" rid="fig4">Figure 4</xref>). These values depended greatly on the land uses and the area of each.</p>
</sec>
<sec id="sec14">
<label>3.3</label>
<title>Carbon footprint</title>
<p>Emissions in CONF were higher in Jalisco, with 4.3&#x2009;&#x00B1;&#x2009;2.2&#x2009;t CO<sub>2</sub>e/ha/year, which contrasted with the higher emissions recorded in SPSF in Chiapas (2.4&#x2009;&#x00B1;&#x2009;0.3&#x2009;t CO<sub>2</sub>e/ha/year). The highest carbon fixation in CONF was in the state of Chiapas, with 7.0&#x2009;&#x00B1;&#x2009;0.4&#x2009;t CO<sub>2</sub>e/ha/year; for SPSF, the highest carbon fixation rate appeared in Jalisco, with 7.4&#x2009;&#x00B1;&#x2009;1.6&#x2009;t CO<sub>2</sub>e/ha/year (<xref ref-type="fig" rid="fig5">Figure 5</xref>). The CF of the livestock sector was negative in the systems and states evaluated, with average values between &#x2212;3.8 and&#x2009;&#x2212;&#x2009;5.6&#x2009;t CO<sub>2</sub>e/ha/year, with no statistical differences (<italic>p</italic>&#x2009;&#x003E;&#x2009;0.05) between production types or between states. The exception to this general trend was the CONF in Jalisco, where the CF was 0.4 and 5.5&#x2009;t CO<sub>2</sub>e/ha/year (<xref ref-type="fig" rid="fig5">Figure 5</xref>), with the CONF being just a net emitter of GHG (0.4&#x2009;t CO<sub>2</sub>e/ha/year).</p>
<fig position="float" id="fig5">
<label>Figure 5</label>
<caption>
<p>Estimated greenhouse gas (GHG) emissions, carbon fixation and carbon footprint according to conventional and silvopastoral systems in the livestock sector in Jalisco, Chiapas and Campeche (Mexico). Error bars indicate standard error of the mean. Different letters indicate statistical differences (<italic>p</italic>&#x2009;&#x003C;&#x2009;0.05) between system types and between states. CONF: conventional farms; SPSF: silvopastoral systems farms.</p>
</caption>
<graphic xlink:href="fsufs-08-1363994-g005.tif"/>
</fig>
<p>The CF of the SPSF was 73% lower than for CONF (&#x2212;5.0 vs. &#x2212;2.9&#x2009;t CO<sub>2</sub>e/ha/year, respectively). The SPSF clearly fix more carbon than the CONF and thus appear to be more environmentally friendly. SPSF presented similar CF for the three states: &#x2212;3.8 vs. &#x2212;5.5 vs. &#x2212;5.6&#x2009;t CO<sub>2</sub>e/ha/year for Chiapas, Jalisco and Campeche, respectively. In contrast, the lowest CF for CONF was achieved in Chiapas (&#x2212;5.3&#x2009;t CO<sub>2</sub>e/ha/year), which had a 43% greater degree of carbon sequestration than in Campeche and much larger than in Jalisco, which had a positive CF &#x2013; that is, they captured less carbon than the GHG they emitted (<xref ref-type="fig" rid="fig6">Figure 6A</xref>).</p>
<fig position="float" id="fig6">
<label>Figure 6</label>
<caption>
<p>Carbon footprint in livestock conventional farms (CONF) and silvopastoral systems farms (SPSF) in Campeche, Chiapas and Jalisco (Mexico). <bold>(A)</bold> Total carbon footprint (CF), <bold>(B)</bold> unitary CF per animal unit (b), <bold>(C)</bold> unitary CF per milk production and <bold>(D)</bold> unitary CF per meat sold (d). Error bars indicate standard error of the mean. Different lowercase letters indicate statistical differences (<italic>p</italic>&#x2009;&#x003C;&#x2009;0.05) between system type by state. Different capital letters indicate statistical differences (<italic>p</italic>&#x2009;&#x003C;&#x2009;0.05) between states.</p>
</caption>
<graphic xlink:href="fsufs-08-1363994-g006.tif"/>
</fig>
</sec>
<sec id="sec15">
<label>3.4</label>
<title>Unitary carbon footprint</title>
<p>SPSF had a unitary CF 11.7% lower than CONF (&#x2212;10.1 vs. &#x2212;9.0&#x2009;t CO<sub>2</sub>e/UA/year, respectively). However, no statistical differences (p&#x2009;&#x003E;&#x2009;0.05) were detected between states and management types. In particular, SPSF in Chiapas presented a unit footprint 23% higher than in Campeche and Jalisco (&#x2212;7.0 vs. &#x2212;11.1 vs. &#x2212;12.2&#x2009;t CO<sub>2</sub>e/AU/yr., respectively) (<xref ref-type="fig" rid="fig6">Figure 6B</xref>).</p>
<p>The CF of cattle farms with milk production did not show significant differences (p&#x2009;&#x003E;&#x2009;0.05) between management systems or between states. The average CF of the CONF amounted to &#x2212;50.3&#x2009;kg CO<sub>2</sub>e/kg of milk, 3.3 times lower than for SPSF (&#x2212;15.1&#x2009;kg CO<sub>2</sub>e/kg of milk). In the state of Chiapas, CONF had the lowest CF (&#x2212;68.6&#x2009;kg CO<sub>2</sub>e/kg of milk), in contrast to the states of Jalisco and Campeche where this value reached &#x2212;16.9 and&#x2009;&#x2212;&#x2009;5.6&#x2009;kg CO<sub>2</sub>e/kg of milk, respectively (<xref ref-type="fig" rid="fig6">Figure 6C</xref>).</p>
<p>The CF from beef farms did not show significant differences between management types (p&#x2009;&#x003E;&#x2009;0.05); however, the average of the SPSF was higher than for the CONF (&#x2212;0.61 vs. &#x2212;0.84&#x2009;t CO<sub>2</sub>e/kg of beef) (<xref ref-type="fig" rid="fig6">Figure 6D</xref>). In SPSF in Chiapas and Campeche, a higher footprint was estimated than that achieved for the same types of farm in Jalisco (&#x2212;0.22 vs. &#x2212;0.48 vs. &#x2212;3.2&#x2009;t CO<sub>2</sub>e/kg of meat). In the state of Campeche, CONF had a higher CF than those with the same management, but in Jalisco and Chiapas (&#x2212;0.13 vs. &#x2212;0.14 vs. &#x2212;1.3&#x2009;t CO<sub>2</sub>e/kg of meat, respectively) (<xref ref-type="fig" rid="fig6">Figure 6D</xref>).</p>
</sec>
</sec>
<sec sec-type="discussion" id="sec16">
<label>4</label>
<title>Discussion</title>
<p>GHG emissions in livestock production systems depend greatly on the characteristics of the herd and how it is fed (<xref ref-type="bibr" rid="ref74">Yunga, 2020</xref>). This was confirmed in the present research, because animals have more options to select higher quality feed when they have more forage area, which would reduce methane emissions (<xref ref-type="bibr" rid="ref33">Guti&#x00E9;rrez Berm&#x00FA;dez and Mendieta Araica, 2022</xref>). Numerous studies (<xref ref-type="bibr" rid="ref42">L&#x00F3;pez-Santiago et al., 2019</xref>; <xref ref-type="bibr" rid="ref16">Carvajal and Andrade, 2020</xref>; <xref ref-type="bibr" rid="ref74">Yunga, 2020</xref>), have confirmed that the use of SPS contributes to reducing GHG emissions from livestock farms. Here, we found that this reduction was on the order of 17%, which is a considerable step toward achieving the goals of returning to livestock as a mitigator of climate change (<xref ref-type="bibr" rid="ref58">Schettini et al., 2021</xref>; <xref ref-type="bibr" rid="ref33">Guti&#x00E9;rrez Berm&#x00FA;dez and Mendieta Araica, 2022</xref>). Despite this, some slight differences can be noted between states, which can basically be explained by the broad characteristics of SPS, which can vary in the abundance, type and size of perennial woody plants (<xref ref-type="bibr" rid="ref72">Villanueva-L&#x00F3;pez et al., 2015</xref>; <xref ref-type="bibr" rid="ref41">L&#x00F3;pez et al., 2019</xref>; <xref ref-type="bibr" rid="ref58">Schettini et al., 2021</xref>).</p>
<p>Animal emissions contributed 98% to total GHG emissions, mainly in the form of methane from enteric fermentation, as has been widely noted (<xref ref-type="bibr" rid="ref46">Molina-Rivera et al., 2019</xref>; <xref ref-type="bibr" rid="ref31">Gonz&#x00E1;lez-Quintero et al., 2021</xref>; <xref ref-type="bibr" rid="ref65">Tongwane and Moeletsi, 2021</xref>; <xref ref-type="bibr" rid="ref68">Uddin et al., 2021</xref>; <xref ref-type="bibr" rid="ref71">Villanueva, 2022</xref>). These findings have been confirmed in Brazil, where the largest impact from dairy production is from enteric fermentation (50&#x2013;52%). In contrast, in semi-confined systems, the largest contribution to farms&#x2019; CF comes from feed (with 48%) (<xref ref-type="bibr" rid="ref19">de L&#x00E9;is et al., 2015</xref>). In Spain, enteric fermentation also explains between 43 and 64% of the CF of livestock systems, which has been linked to system intensification and a grazing diet (<xref ref-type="bibr" rid="ref21">Eldesouky et al., 2018</xref>). Here, the second most important component of the farms&#x2019; CF turned out to be nitrogen fertilization, which is commonly the most heavily weighted in the field of agriculture (<xref ref-type="bibr" rid="ref5">Andrade et al., 2014b</xref>, <xref ref-type="bibr" rid="ref7">2015</xref>).</p>
<p>Use of SPS has also been shown to have positive carbon fixation results, which can reverse the CF. For example, <xref ref-type="bibr" rid="ref14">Camero (2020)</xref> recorded 3.8&#x2009;t C/ha/year of carbon fixation, which offset emissions from <italic>Brachiaria brizantha</italic> and <italic>Erythrina berteroana</italic> in northern Costa Rica. In contrast, in a previous study in Campeche, no differences in GHG emissions were found between extensive monoculture grazing, intensive SPS and low-intensity system or fallows, because 92% of animal consumption was grasses in all systems and the area devoted to leguminous crops and fallows was only 12 and 15%, respectively (<xref ref-type="bibr" rid="ref46">Molina-Rivera et al., 2019</xref>).</p>
<p>Switching from degraded pastures to any other type of land use system always results in positive benefits for climate change mitigation, because it allows for carbon concentration (<xref ref-type="bibr" rid="ref8">Apan et al., 2021</xref>). SPS allow such reconversion &#x2013; that is, from net CO<sub>2</sub> emitting systems, such as degraded pastures, to net carbon-fixing systems &#x2013; while at the same time increasing production, quality and improving the supply of other ecosystem services (<xref ref-type="bibr" rid="ref4">Andrade et al., 2008</xref>; <xref ref-type="bibr" rid="ref42">L&#x00F3;pez-Santiago et al., 2019</xref>; <xref ref-type="bibr" rid="ref8">Apan et al., 2021</xref>; <xref ref-type="bibr" rid="ref58">Schettini et al., 2021</xref>).</p>
<p>Although most of the livestock farms evaluated presented a negative CF (that is, they fixed more carbon than they emitted), those involving SPS contributed more to climate change mitigation by fixing more carbon per animal unit or per unit of milk or meat sold. However, there was an exception in Chiapas, where CONF appeared able to fix more carbon than SPSF. This may be due to the nature of SPS, which could be very similar to conventional systems, or because the level of livestock production on conventional cattle ranches is much higher than on those that use trees (<xref ref-type="bibr" rid="ref8">Apan et al., 2021</xref>). The application of these results should thus consider local information, because different factors affect CF, including the uncertainty in the permanence of carbon in biomass.</p>
<p>The CF depends greatly on the extent to which the country has developed and their cattle production. Countries such as Norway, Sweden, Portugal, Denmark and the Netherlands have reported a CF for conventional cattle systems higher than 1&#x2009;kg CO<sub>2</sub>e/kg milk (<xref ref-type="bibr" rid="ref19">de L&#x00E9;is et al., 2015</xref>). In contrast, confined dairy production systems Brazil showed a lower CF than semi-confined or grazing systems (0.54 vs. 0.78 and 0.74&#x2009;kg CO<sub>2</sub>e/kg milk, respectively) (<xref ref-type="bibr" rid="ref19">de L&#x00E9;is et al., 2015</xref>). In temperate and tropical Mexico, these values have been estimated at 0.55 and 0.91&#x2009;kg CO<sub>2</sub>e/kg milk, respectively; while values were around 0.53&#x2009;kg CO<sub>2</sub>e/kg milk in India (<xref ref-type="bibr" rid="ref24">Garg et al., 2013</xref>). In Colombia, small cattle ranches with low levels of technology had a CF of 3.75&#x2009;kg CO<sub>2</sub>e/kg milk (<xref ref-type="bibr" rid="ref52">P&#x00E1;ez et al., 2018</xref>) and 3.3&#x2009;kg CO<sub>2</sub>e/kg milk and 10.5&#x2009;kg CO<sub>2</sub>e/kg meat sold in dual-purpose cattle ranching (<xref ref-type="bibr" rid="ref31">Gonz&#x00E1;lez-Quintero et al., 2021</xref>). The differences from this study are possibly related to higher levels of milk production, consistent diet quality, lower use of external inputs and the presence of trees on farms (<xref ref-type="bibr" rid="ref71">Villanueva, 2022</xref>).</p>
<p>Looking at meat production, the CF was 32.5&#x2009;kg CO<sub>2</sub>e/kg of beef and 28.0&#x2009;kg CO<sub>2</sub>e/kg of meat of small ruminants for 2010 in Spain (<xref ref-type="bibr" rid="ref1">Aguilera et al., 2020</xref>). Specialized dairy production systems in Costa Rica have a CF between 2.28 and 11.06&#x2009;kg CO<sub>2</sub>e/kg, and dual-purpose livestock contribute slightly more, with values between 5.45 and 23.72&#x2009;kg CO<sub>2</sub>e/kg for milk and LWG, respectively (<xref ref-type="bibr" rid="ref71">Villanueva, 2022</xref>). Meanwhile, in hot and humid areas of Mexico, <xref ref-type="bibr" rid="ref46">Molina-Rivera et al. (2019)</xref> found that emissions of 23.1&#x2009;kg CO<sub>2</sub>e/kg live weight for beef production.</p>
<p>Latin America is seen as an area with potential for improving food security, where cattle ranching is presented as an opportunity for sustainable economic growth in Mexico (<xref ref-type="bibr" rid="ref8">Apan et al., 2021</xref>). However, improving livestock farming requires cooperation between actors to adopt improved pastures and implement productive and environmentally friendly practices, such as SPS, which support the initiatives of the Global Roundtable on Sustainable Livestock (<xref ref-type="bibr" rid="ref66">Triana-&#x00C1;ngel and Burkart, 2021</xref>). Rigorous local studies are still needed on sustainable soil development in agricultural and forestry practices, given that the efficiency of mitigation and adaptation strategies depends on climatic, edaphic and social characteristics, as well as the historical pattern of land use and management (<xref ref-type="bibr" rid="ref10">Aryal et al., 2020</xref>; <xref ref-type="bibr" rid="ref2">Alexandre et al., 2021</xref>). Unification of methodologies is also needed to estimate the CF of the sector, including a thorough analysis of the type of system, number of individuals, the technological level in each link of the production chain (<xref ref-type="bibr" rid="ref52">P&#x00E1;ez et al., 2018</xref>), associated plant species, livestock genotype, integrated feeding strategies and best agricultural management practices (<xref ref-type="bibr" rid="ref10">Aryal et al., 2020</xref>; <xref ref-type="bibr" rid="ref31">Gonz&#x00E1;lez-Quintero et al., 2021</xref>).</p>
<p>Livestock CF monitoring can help identify opportunities to improve environmental performance and allows tracking and evaluation of environmental impacts that contribute to climate change and land use changes (<xref ref-type="bibr" rid="ref19">de L&#x00E9;is et al., 2015</xref>). Sustainable cattle ranching that includes native trees and shrubs provides other benefits that contribute to biodiversity, reforestation and added value for timber and non-timber forest products, which in turn can strengthen the family and cooperative economy (<xref ref-type="bibr" rid="ref57">Ru&#x00ED;z et al., 2021</xref>).</p>
</sec>
<sec sec-type="conclusions" id="sec17">
<label>5</label>
<title>Conclusion</title>
<p>The CF of livestock farms in the three states studied was dependent on the total forage area and the number of animals. In this exercise, SPS contributed to reduce total GHG emissions &#x2013; 8.0 to 5.7&#x2009;t CO<sub>2</sub>e/ha/year &#x2013; mainly due to improvements in the animals&#x2019; diet and reductions in the doses of nitrogen fertilizers. SPS also increased carbon fixation in total biomass and soils, clearly providing a double benefit in terms of GHG emissions reduction and carbon fixation. SPSF increase a negative CF 73% lower than CONF, which demonstrates the importance of SPS in mitigating climate change.</p>
<p>In all management type&#x2013;state combinations, except for CONF in Jalisco, a negative CF was found &#x2013; that is, carbon fixation in biomass and soils was greater than GHG emissions. This demonstrates that these farms are currently mitigating climate change by fixing carbon. However, the use of SPS on livestock farms currently contributes to an increase the net carbon sequestration. The CF per animal unit and per unit of milk produced and meat sold turned out to be negative and quite variable among the different combinations of state and management types. In any case, the best CF values were found in the CONF of Jalisco for milk and in the SPSF of Campeche for the production and sale of meat. The findings of this study provide the basis for policy and technical guidelines to promote more environmentally friendly livestock farms by fixing a greater amount of atmospheric CO<sub>2</sub>.</p>
</sec>
<sec sec-type="data-availability" id="sec18">
<title>Data availability statement</title>
<p>The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author.</p>
</sec>
<sec sec-type="author-contributions" id="sec19">
<title>Author contributions</title>
<p>HA: Conceptualization, Writing &#x2013; original draft, Writing &#x2013; review &#x0026; editing. AV: Validation, Writing &#x2013; review &#x0026; editing. AM-S: Supervision, Validation, Writing &#x2013; review &#x0026; editing. CV: Formal analysis, Writing &#x2013; review &#x0026; editing. JJ-T: Methodology, Validation, Writing &#x2013; review &#x0026; editing. JB-S: Methodology, Validation, Writing &#x2013; review &#x0026; editing. EP: Methodology, Validation, Writing &#x2013; review &#x0026; editing. MI: Funding acquisition, Investigation, Supervision, Writing &#x2013; review &#x0026; editing. CS: Funding acquisition, Methodology, Supervision, Writing &#x2013; review &#x0026; editing.</p>
</sec>
</body>
<back>
<sec sec-type="funding-information" id="sec20">
<title>Funding</title>
<p>The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.</p>
</sec>
<ack>
<p>The authors would like to thank the BioPaSOS project and especially the local technicians and producers who kindly shared their information with us.</p>
</ack>
<sec sec-type="COI-statement" id="sec21">
<title>Conflict of interest</title>
<p>The manuscript was prepared and reviewed by the authors, who declare that there are no conflicts of interest that would jeopardize the validity of the results presented.</p>
</sec>
<sec sec-type="disclaimer" id="sec22">
<title>Publisher&#x2019;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
<ref-list>
<title>References</title>
<ref id="ref1">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Aguilera</surname> <given-names>E.</given-names></name> <name><surname>Pi&#x00F1;ero</surname> <given-names>P.</given-names></name> <name><surname>Infante Amate</surname> <given-names>J.</given-names></name> <name><surname>Gonz&#x00E1;lez de Molina</surname> <given-names>M.</given-names></name> <name><surname>Lassaletta</surname> <given-names>L.</given-names></name> <name><surname>Sanz Cobe&#x00F1;a</surname> <given-names>A.</given-names></name></person-group> (<year>2020</year>). <source>Emisiones de gases de efecto invernadero en el sistema agroalimentario y huella de carbono de la alimentaci&#x00F3;n en Espa&#x00F1;a</source>. <publisher-loc>Espa&#x00F1;a</publisher-loc>: <publisher-name>Real Academia de Ingenier&#x00ED;a</publisher-name>.</citation>
</ref>
<ref id="ref2">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Alexandre</surname> <given-names>G.</given-names></name> <name><surname>Cheval</surname> <given-names>A.</given-names></name> <name><surname>Perrette</surname> <given-names>J.</given-names></name> <name><surname>Apotout</surname> <given-names>M.</given-names></name> <name><surname>Diman</surname> <given-names>J. L.</given-names></name> <name><surname>Larade</surname> <given-names>A.</given-names></name> <etal/></person-group>. (<year>2021</year>). <article-title>Livestock activities in agroforestry systems in Guadeloupe: systems of production and functions</article-title>. <source>Agrofor. Syst.</source> <volume>95</volume>, <fpage>1445</fpage>&#x2013;<lpage>1458</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10457-021-00651-5</pub-id></citation>
</ref>
<ref id="ref3">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Ali</surname> <given-names>A.</given-names></name> <name><surname>Akram</surname> <given-names>W.</given-names></name> <name><surname>Ahmad</surname> <given-names>F.</given-names></name> <name><surname>Ahmad</surname> <given-names>M.</given-names></name></person-group> (<year>2020</year>). <article-title>Dynamic relationship among agriculture-energy-forestry and carbon dioxide (CO2) emissions: empirical evidence from China</article-title>. <source>Environ. Sci. Pollut. Res.</source> <volume>27</volume>, <fpage>34078</fpage>&#x2013;<lpage>34089</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s11356-020-09560-z</pub-id></citation>
</ref>
<ref id="ref4">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Andrade</surname> <given-names>H. J.</given-names></name> <name><surname>Brook</surname> <given-names>R.</given-names></name> <name><surname>Ibrahim</surname> <given-names>M.</given-names></name></person-group> (<year>2008</year>). <article-title>Growth, production and carbon sequestration of silvopastoral systems with native timber species in the dry lowlands of Costa Rica</article-title>. <source>Plant Soil</source> <volume>308</volume>, <fpage>11</fpage>&#x2013;<lpage>22</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s11104-008-9600-x</pub-id></citation>
</ref>
<ref id="ref5">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Andrade</surname> <given-names>H. J.</given-names></name> <name><surname>Campo</surname> <given-names>O.</given-names></name> <name><surname>Segura</surname> <given-names>M. A.</given-names></name></person-group> (<year>2014b</year>). <article-title>Huella de carbono del sistema de producci&#x00F3;n de arroz (<italic>Oryza sativa</italic>) en el municipio de Campoalegre, Huila</article-title>. <source>Colombia. Corpoica Ciencia y Tecnolog&#x00ED;a Agropecuaria.</source> <volume>15</volume>, <fpage>25</fpage>&#x2013;<lpage>31</lpage>,</citation>
</ref>
<ref id="ref6">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Andrade</surname> <given-names>H. J.</given-names></name> <name><surname>Mar&#x00ED;n</surname> <given-names>L. M.</given-names></name> <name><surname>Pach&#x00F3;n</surname> <given-names>D. P.</given-names></name></person-group> (<year>2014a</year>). <article-title>Fijaci&#x00F3;n de carbono y porcentaje de sombra en sistemas de producci&#x00F3;n de caf&#x00E9; (<italic>Coffea arabica</italic> L.) en el L&#x00ED;bano, Tolima, Colombia</article-title>. <source>Bioagro.</source> <volume>26</volume>, <fpage>127</fpage>&#x2013;<lpage>132</lpage>,</citation>
</ref>
<ref id="ref7">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Andrade</surname> <given-names>H. J.</given-names></name> <name><surname>Segura</surname> <given-names>M. A.</given-names></name> <name><surname>Varona</surname> <given-names>J. P.</given-names></name></person-group> (<year>2015</year>). <article-title>Estimaci&#x00F3;n de huella de carbono del sistema de producci&#x00F3;n de ca&#x00F1;a de az&#x00FA;car (<italic>Saccharum officinarum</italic>) en Palmira, Valle del Cauca, Colombia</article-title>. <source>Revista de Investigaci&#x00F3;n Agraria y Ambiental.</source> <volume>6</volume>, <fpage>19</fpage>&#x2013;<lpage>27</lpage>,</citation>
</ref>
<ref id="ref8">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Apan</surname> <given-names>G. W.</given-names></name> <name><surname>Jim&#x00E9;nez</surname> <given-names>G.</given-names></name> <name><surname>Nahed</surname> <given-names>J.</given-names></name> <name><surname>P&#x00E9;rez</surname> <given-names>E.</given-names></name> <name><surname>Pi&#x00F1;eiro</surname> <given-names>&#x00C1;. T.</given-names></name></person-group> (<year>2021</year>). <article-title>Masificaci&#x00F3;n de sistemas silvopastoriles: un largo y sinuoso camino</article-title>. <source>Tropical and Subtropical Agroecosystems.</source> <volume>24</volume>, <fpage>1</fpage>&#x2013;<lpage>17</lpage>,</citation>
</ref>
<ref id="ref9">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Aryal</surname> <given-names>D. R.</given-names></name> <name><surname>Morales-Ruiz</surname> <given-names>D. E.</given-names></name> <name><surname>L&#x00F3;pez-Cruz</surname> <given-names>S.</given-names></name> <name><surname>Tondop&#x00F3;-Marroqu&#x00ED;n</surname> <given-names>C. N.</given-names></name> <name><surname>Lara-Nucamendi</surname> <given-names>A.</given-names></name> <name><surname>Jim&#x00E9;nez-Trujillo</surname> <given-names>J. A.</given-names></name> <etal/></person-group>. (<year>2022</year>). <article-title>Silvopastoral systems and remnant forests enhance carbon storage in livestock-dominated landscapes in Mexico</article-title>. <source>Sci. Rep.</source> <volume>12</volume>:<fpage>16769</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41598-022-21089-4</pub-id></citation>
</ref>
<ref id="ref10">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Aryal</surname> <given-names>J. P.</given-names></name> <name><surname>Rahut</surname> <given-names>D. B.</given-names></name> <name><surname>Sapkota</surname> <given-names>T. B.</given-names></name> <name><surname>Khurana</surname> <given-names>R.</given-names></name> <name><surname>Khatri-Chhetri</surname> <given-names>A.</given-names></name></person-group> (<year>2020</year>). <article-title>Climate change mitigation options among farmers in South Asia</article-title>. <source>Environ. Dev. Sustain.</source> <volume>22</volume>, <fpage>3267</fpage>&#x2013;<lpage>3289</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10668-019-00345-0</pub-id></citation>
</ref>
<ref id="ref11">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Bautista</surname> <given-names>M. A.</given-names></name> <name><surname>Bonales</surname> <given-names>J.</given-names></name> <name><surname>Val</surname> <given-names>D.</given-names></name></person-group> (<year>2020</year>). <article-title>Din&#x00E1;micas de la cadena de bovinos productores de carne mexicana en el siglo XXI</article-title>, in <source>Factores Cr&#x00ED;ticos y Estrat&#x00E9;gicos en la Interacci&#x00F3;n Territorial Desaf&#x00ED;os Actuales y Escenarios Futuros</source>, eds. <person-group person-group-type="editor"><name><surname>Vega</surname> <given-names>S.</given-names><prefix>De la</prefix></name> <name><surname>R&#x00F3;zga</surname> <given-names>R. E.</given-names></name> <name><surname>Hoyos</surname> <given-names>C.</given-names></name></person-group>. <publisher-loc>Mexico</publisher-loc>: <publisher-name>Universidad Nacional Aut&#x00F3;noma de M&#x00E9;xico y Asociaci&#x00F3;n Mexicana de Ciencias para el Desarrollo Regional A.C</publisher-name>.</citation>
</ref>
<ref id="ref12">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll1">Biodiversidad y Paisajes Ganaderos Agrosilvopastoriles Sostenibles [BioPaSOS]. (s.f.)</collab>
</person-group> (<year>2017</year>). <source>Caracterizaci&#x00F3;n de la ganader&#x00ED;a bovina en el estado de Campeche, M&#x00E9;xico</source>. <publisher-loc>M&#x00E9;xico</publisher-loc>: <publisher-name>CATIE, SAGARPA, CONABIO-IICA, Ministerio Federal de Medio Ambiente, Protecci&#x00F3;n de la Naturaleza y Seguridad Nuclear</publisher-name>.</citation>
</ref>
<ref id="ref13">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Brook</surname> <given-names>R.</given-names></name> <name><surname>Forster</surname> <given-names>E.</given-names></name> <name><surname>Styles</surname> <given-names>D.</given-names></name> <name><surname>Mazzetto</surname> <given-names>A. M.</given-names></name> <name><surname>Arndt</surname> <given-names>C.</given-names></name> <name><surname>Esquivel</surname> <given-names>M. J.</given-names></name> <etal/></person-group>. (<year>2022</year>). <article-title>Silvopastoral systems for offsetting livestock emissions in the tropics: a case study of a dairy farm in Costa Rica</article-title>. <source>Agron. Sustain. Dev.</source> <volume>42</volume>:<fpage>101</fpage>. doi: <pub-id pub-id-type="doi">10.1007/s13593-022-00834-z</pub-id></citation>
</ref>
<ref id="ref14">
<citation citation-type="journal"><person-group person-group-type="author">
<name><surname>Camero</surname> <given-names>L. A.</given-names></name>
</person-group> (<year>2020</year>). <article-title>Fijaci&#x00F3;n de carbono en un sistema silvopastoril (<italic>Erythrina berteroana</italic> Urban y <italic>Brachiaria brizantha</italic> CV Toledo) de una explotaci&#x00F3;n lechera en la Regi&#x00F3;n Huetar Norte de Costa Rica</article-title>. <source>Revista AgroInnovaci&#x00F3;n en el Tr&#x00F3;pico H&#x00FA;medo.</source> <volume>2</volume>, <fpage>19</fpage>&#x2013;<lpage>26</lpage>. doi: <pub-id pub-id-type="doi">10.18860/rath.v2i2.5194</pub-id></citation>
</ref>
<ref id="ref15">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Canu</surname> <given-names>F.</given-names></name> <name><surname>Wretlind</surname> <given-names>P. H.</given-names></name> <name><surname>Audia</surname> <given-names>I.</given-names></name> <name><surname>Tobar</surname> <given-names>D.</given-names></name> <name><surname>Andrade</surname> <given-names>H. J.</given-names></name></person-group> (<year>2018</year>). <source>NAMA para un sector ganadero bajo en carbono y resiliente al clima en Honduras</source>. <publisher-loc>Dinamarca</publisher-loc>: <publisher-name>Technical University of Denmark, Gobierno de la Republica de Honduras, CATIE, UNEP DTU Partnership, NDF, NEFCO</publisher-name>.</citation>
</ref>
<ref id="ref16">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Carvajal</surname> <given-names>B. N.</given-names></name> <name><surname>Andrade</surname> <given-names>H. J.</given-names></name></person-group> (<year>2020</year>). <article-title>Captura de carbono en biomasa de sistemas de uso del suelo, municipio de Yopal, Casanare Colombia</article-title>. <source>Orinoquia</source> <volume>24</volume>, <fpage>13</fpage>&#x2013;<lpage>22</lpage>. doi: <pub-id pub-id-type="doi">10.22579/20112629.587</pub-id></citation>
</ref>
<ref id="ref17">
<citation citation-type="other"><person-group person-group-type="author">
<collab id="coll2">Centro Agron&#x00F3;mico Tropical de Investigaci&#x00F3;n y Ense&#x00F1;anza [CATIE]</collab>
</person-group>. (<year>2010</year>). Determinaci&#x00F3;n del balance de gases efecto invernadero en fincas ganaderas de la regi&#x00F3;n Chorotega, como elemento de referencia para mejorar la competitividad: Programa de fomento de la producci&#x00F3;n agropecuaria sostenible (PFPAS)-Programa de Ganader&#x00ED;a y Manejo del medio ambiente (GAMMA). Available at: <ext-link xlink:href="http://www.mag.go.cr/bibliotecavirtual/P40-9906.pdf" ext-link-type="uri">http://www.mag.go.cr/bibliotecavirtual/P40-9906.pdf</ext-link> (Accessed August, 2023).</citation>
</ref>
<ref id="ref18">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>de Figueiredo</surname> <given-names>E. D.</given-names></name> <name><surname>Panosso</surname> <given-names>A. R.</given-names></name> <name><surname>de Oliveira</surname> <given-names>R.</given-names></name> <name><surname>Teixeira</surname> <given-names>D.</given-names></name> <name><surname>Berchielli</surname> <given-names>T. T.</given-names></name> <name><surname>La Scala</surname> <given-names>N.</given-names></name></person-group> (<year>2016</year>). <article-title>Soil CO2-C emissions and correlations with soil properties in degrade and managed pastures in southern Brazil</article-title>. <source>Land Degrad. Dev.</source> <volume>28</volume>, <fpage>1263</fpage>&#x2013;<lpage>1273</lpage>. doi: <pub-id pub-id-type="doi">10.1002/ldr.2524</pub-id></citation>
</ref>
<ref id="ref19">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>de L&#x00E9;is</surname> <given-names>C. M.</given-names></name> <name><surname>Cherubini</surname> <given-names>E.</given-names></name> <name><surname>Ruviaro</surname> <given-names>C. F.</given-names></name> <name><surname>da Silva</surname> <given-names>V. P.</given-names></name> <name><surname>Nascimento</surname> <given-names>V.</given-names></name> <name><surname>Spies</surname> <given-names>A.</given-names></name> <etal/></person-group>. (<year>2015</year>). <article-title>Carbon footprint of milk production in Brazil: a comparative case study</article-title>. <source>Int. J. Life Cycle Assess.</source> <volume>20</volume>, <fpage>46</fpage>&#x2013;<lpage>60</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s11367-014-0813-3</pub-id></citation>
</ref>
<ref id="ref20">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Di Rienzo</surname> <given-names>J.</given-names></name> <name><surname>Casanoves</surname> <given-names>F.</given-names></name> <name><surname>Gonz&#x00E1;lez</surname> <given-names>L.</given-names></name> <name><surname>Tablada</surname> <given-names>M.</given-names></name> <name><surname>Robledo</surname> <given-names>C.</given-names></name> <name><surname>Balzarini</surname> <given-names>Y.</given-names></name> <etal/></person-group>. (<year>2019</year>). <source>Software</source>. <publisher-loc>C&#x00F3;rdoba, Argentina</publisher-loc>: <publisher-name>Grupo InfoStat, FCA, Universidad Nacional de C&#x00F3;rdoba</publisher-name>.</citation>
</ref>
<ref id="ref21">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Eldesouky</surname> <given-names>A.</given-names></name> <name><surname>Mesias</surname> <given-names>F. J.</given-names></name> <name><surname>Elghannam</surname> <given-names>A.</given-names></name> <name><surname>Escribano</surname> <given-names>M.</given-names></name></person-group> (<year>2018</year>). <article-title>Can extensification compensate livestock greenhouse gas emissions? A study of the carbon footprint in Spanish agroforestry systems</article-title>. <source>J. Clean. Prod.</source> <volume>200</volume>, <fpage>28</fpage>&#x2013;<lpage>38</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.jclepro.2018.07.279</pub-id></citation>
</ref>
<ref id="ref22">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Elshimy</surname> <given-names>M.</given-names></name> <name><surname>El-Aasar</surname> <given-names>K.</given-names></name></person-group> (<year>2020</year>). <article-title>Carbon footprint, renewable energy, non-renewable energy, and livestock: testing the environmental Kuznets curve hypothesis for the Arab world</article-title>. <source>Environ. Dev. Sustain.</source> <volume>22</volume>, <fpage>6985</fpage>&#x2013;<lpage>7012</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10668-019-00523-0</pub-id></citation>
</ref>
<ref id="ref23">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Fonseca</surname> <given-names>W.</given-names></name> <name><surname>Rey Benayas</surname> <given-names>J. M.</given-names></name> <name><surname>Alice</surname> <given-names>F. E.</given-names></name></person-group> (<year>2011</year>). <article-title>Carbon accumulation in the biomass and soil of different ages in the humid tropics of Costa Rica</article-title>. <source>For. Ecol. Manag.</source> <volume>262</volume>, <fpage>1400</fpage>&#x2013;<lpage>1408</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.foreco.2011.06.036</pub-id></citation>
</ref>
<ref id="ref24">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Garg</surname> <given-names>M. R.</given-names></name> <name><surname>Sherasiaa</surname> <given-names>P. L.</given-names></name> <name><surname>Bhanderia</surname> <given-names>B. M.</given-names></name> <name><surname>Phondbaa</surname> <given-names>B. T.</given-names></name> <name><surname>Shelkea</surname> <given-names>S. K.</given-names></name> <name><surname>Makkar</surname> <given-names>H. P.</given-names></name></person-group> (<year>2013</year>). <article-title>Effects of feeding nutritionally balanced rations on animal productivity, feed conversion efficiency, feed nitrogen use efficiency, rumen microbial protein supply, parasitic load, immunity and enteric methane emissions of milking animals under field conditions</article-title>. <source>Anim. Feed Sci. Technol.</source> <volume>179</volume>, <fpage>24</fpage>&#x2013;<lpage>35</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.anifeedsci.2012.11.005</pub-id></citation>
</ref>
<ref id="ref25">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Gerber</surname> <given-names>P. J.</given-names></name> <name><surname>Steinfeld</surname> <given-names>H.</given-names></name> <name><surname>Henderson</surname> <given-names>B.</given-names></name> <name><surname>Mottet</surname> <given-names>A.</given-names></name> <name><surname>Opio</surname> <given-names>C.</given-names></name> <name><surname>Dijkman</surname> <given-names>J.</given-names></name> <etal/></person-group>. (<year>2013</year>). <source>Tackling climate change through livestock &#x2013; A global assessment of emissions and mitigation opportunities</source>. <publisher-loc>Rome</publisher-loc>: <publisher-name>Food and Agriculture Organization of the United Nations (FAO)</publisher-name>.</citation>
</ref>
<ref id="ref26">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Ghosh</surname> <given-names>A.</given-names></name> <name><surname>Misra</surname> <given-names>S.</given-names></name> <name><surname>Bhattacharyya</surname> <given-names>R.</given-names></name> <name><surname>Sarkar</surname> <given-names>A.</given-names></name> <name><surname>Kumar</surname> <given-names>A.</given-names></name> <name><surname>Chandra</surname> <given-names>V.</given-names></name> <etal/></person-group>. (<year>2020</year>). <article-title>Agriculture, dairy and fishery farming practices and greenhouse gas emission footprint: a strategic appraisal for mitigation</article-title>. <source>Environ. Sci. Pollut. Res.</source> <volume>27</volume>, <fpage>10160</fpage>&#x2013;<lpage>10184</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s11356-020-07949-4</pub-id></citation>
</ref>
<ref id="ref27">
<citation citation-type="book"><person-group person-group-type="author">
<name><surname>de Jalisco</surname> <given-names>G.</given-names></name>
</person-group> (<year>2011</year>). <source>Plan Regional de Desarrollo 2030. Regi&#x00F3;n 01 Norte</source>. <edition>2nd</edition> Edn. <publisher-loc>Jalisco, M&#x00E9;xico</publisher-loc>: <publisher-name>Esp&#x00ED;ritu de la tierra</publisher-name>.</citation>
</ref>
<ref id="ref28">
<citation citation-type="other"><person-group person-group-type="author">
<name><surname>de M&#x00E9;xico</surname> <given-names>G.</given-names></name>
</person-group>. (<year>2018</year>). Proyecciones de la poblaci&#x00F3;n de M&#x00E9;xico y de las entidades federativas 2016&#x2013;2050. M&#x00E9;xico. Available at: <ext-link xlink:href="https://www.gob.mx/cms/uploads/attachment/file/390824/InfografaProyeccionesdelapoblacindeMxico.pdf" ext-link-type="uri">https://www.gob.mx/cms/uploads/attachment/file/390824/InfografaProyeccionesdelapoblacindeMxico.pdf</ext-link>.</citation>
</ref>
<ref id="ref29">
<citation citation-type="other"><person-group person-group-type="author">
<collab id="coll3">Gobierno del Estado de Campeche</collab>
</person-group>. (<year>2015</year>). Plan estatal de desarrollo Campeche 2015&#x2013;2021. Available at: <ext-link xlink:href="https://n9.cl/gltwe" ext-link-type="uri">https://n9.cl/gltwe</ext-link> (Accessed August, 2023).</citation>
</ref>
<ref id="ref30">
<citation citation-type="other"><person-group person-group-type="author">
<collab id="coll4">Gobierno del Estado de Chiapas</collab>
</person-group>. (<year>2019</year>). Plan estatal de desarrollo Chiapas 2019&#x2013;2024. Available at: <ext-link xlink:href="http://www.haciendachiapas.gob.mx/planeacion/Informacion/PED/PED-2019.pdf" ext-link-type="uri">http://www.haciendachiapas.gob.mx/planeacion/Informacion/PED/PED-2019.pdf</ext-link> (Accessed October 18, 2023).</citation>
</ref>
<ref id="ref31">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Gonz&#x00E1;lez-Quintero</surname> <given-names>R.</given-names></name> <name><surname>Kristensen</surname> <given-names>T.</given-names></name> <name><surname>S&#x00E1;nchez-Pinz&#x00F3;n</surname> <given-names>M. S.</given-names></name> <name><surname>Bol&#x00ED;var-Vergara</surname> <given-names>D. M.</given-names></name> <name><surname>Chirinda</surname> <given-names>N.</given-names></name> <name><surname>Arango</surname> <given-names>J.</given-names></name> <etal/></person-group>. (<year>2021</year>). <article-title>Carbon footprint, non-renewable energy and land use of dual-purpose cattle systems in Colombia using a life cycle assessment approach</article-title>. <source>Livest. Sci.</source> <volume>244</volume>:<fpage>104330</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.livsci.2020.104330</pub-id></citation>
</ref>
<ref id="ref32">
<citation citation-type="other"><person-group person-group-type="author">
<collab id="coll5">Grain</collab>
</person-group>. (<year>2017</year>). Big meat and dairy&#x2019;s supersized climate footprint. Available at: <ext-link xlink:href="https://www.grain.org/article/entries/5825-big-meat-and-dairy-s-supersized-climate-footprint" ext-link-type="uri">https://www.grain.org/article/entries/5825-big-meat-and-dairy-s-supersized-climate-footprint</ext-link> (Accessed October 18, 2023).</citation>
</ref>
<ref id="ref33">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Guti&#x00E9;rrez Berm&#x00FA;dez</surname> <given-names>C. C.</given-names></name> <name><surname>Mendieta Araica</surname> <given-names>B. G.</given-names></name></person-group> (<year>2022</year>). <article-title>Sistemas silvopastoriles: una alternativa para la ganader&#x00ED;a bovina sostenible</article-title>. <source>La Calera.</source> <volume>22</volume>, <fpage>1</fpage>&#x2013;<lpage>10</lpage>. doi: <pub-id pub-id-type="doi">10.5377/calera.v22i38.14193</pub-id></citation>
</ref>
<ref id="ref34">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Hawkins</surname> <given-names>J.</given-names></name> <name><surname>Yesuf</surname> <given-names>G.</given-names></name> <name><surname>Zijlstra</surname> <given-names>M.</given-names></name> <name><surname>Schoneveld</surname> <given-names>G. C.</given-names></name> <name><surname>Rufino</surname> <given-names>M. C.</given-names></name></person-group> (<year>2021</year>). <article-title>Feeding efficiency gains can increase the greenhouse gas mitigation potential of the Tanzanian dairy sector</article-title>. <source>Sci. Rep.</source> <volume>11</volume>:<fpage>4190</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41598-021-83475-8</pub-id></citation>
</ref>
<ref id="ref35">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll6">Instituto Nacional de ecolog&#x00ED;a y Cambio Clim&#x00E1;tico [INECC]</collab>
</person-group> (<year>2014</year>). <source>Factores de emisi&#x00F3;n para los diferentes tipos de combustibles f&#x00F3;siles y alternativos que se consumen en M&#x00E9;xico</source>. <publisher-loc>Coyoac&#x00E1;n, M&#x00E9;xico</publisher-loc>: <publisher-name>Secretar&#x00ED;a de Medio Ambiente y Recursos Naturales</publisher-name>.</citation>
</ref>
<ref id="ref36">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll7">Instituto Nacional de ecolog&#x00ED;a y Cambio Clim&#x00E1;tico [INECC]</collab>
</person-group> (<year>2018</year>). <source>Inventario Nacional de Emisiones de Gases y Compuestos de Efecto Invernadero &#x2013; 2015</source>. <publisher-loc>M&#x00E9;xico</publisher-loc>: <publisher-name>INECC</publisher-name>.</citation>
</ref>
<ref id="ref37">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll8">Instituto Nacional de Estad&#x00ED;stica y Geograf&#x00ED;a [INEGI]</collab>
</person-group> (<year>2016</year>). <source>Anuario estad&#x00ED;stico y geogr&#x00E1;fico de Chiapas 2016</source>. <publisher-loc>M&#x00E9;xico</publisher-loc>: <publisher-name>Gobierno del Estado de Chiapas</publisher-name>.</citation>
</ref>
<ref id="ref38">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll9">Intergovernmental Panel on Climate Change [IPCC]</collab>
</person-group> (<year>2006</year>). <source>Guidelines for national greenhouse gas inventories</source>. <publisher-loc>Tokyo, Japan</publisher-loc>: <publisher-name>Institute for global environmental strategies (IGES)</publisher-name>.</citation>
</ref>
<ref id="ref39">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll10">Intergovernmental Panel on Climate Change [IPCC]</collab>
</person-group> (<year>2013</year>). &#x201C;<article-title>Climate change 2013: the physical science basis</article-title>&#x201D; in <source>Contribution of working group I to the fifth assessment report of the intergovernmental panel on climate change</source>. eds. <person-group person-group-type="editor"><name><surname>Stocker</surname> <given-names>T. F.</given-names></name> <name><surname>Qin</surname> <given-names>D.</given-names></name> <name><surname>Plattner</surname> <given-names>G. K.</given-names></name> <name><surname>Tignor</surname> <given-names>M.</given-names></name> <name><surname>Allen</surname> <given-names>S. K.</given-names></name> <name><surname>Boschung</surname> <given-names>J.</given-names></name></person-group> (<publisher-loc>Cambridge, UK</publisher-loc>: <publisher-name>Cambridge University Press</publisher-name>).</citation>
</ref>
<ref id="ref40">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll11">International Energy Agency [IEA]</collab>
</person-group> (<year>2020</year>). <source>Global energy review 2020</source>. <publisher-loc>Paris</publisher-loc>: <publisher-name>IEA Int. Energy Agency</publisher-name>.</citation>
</ref>
<ref id="ref41">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>L&#x00F3;pez</surname> <given-names>O.</given-names></name> <name><surname>Lamela</surname> <given-names>L.</given-names></name> <name><surname>S&#x00E1;nchez</surname> <given-names>T.</given-names></name> <name><surname>Olivera</surname> <given-names>Y.</given-names></name> <name><surname>Garc&#x00ED;a</surname> <given-names>R.</given-names></name> <name><surname>Herrera</surname> <given-names>M.</given-names></name> <etal/></person-group>. (<year>2019</year>). <article-title>Evaluaci&#x00F3;n del valor nutricional de los forrajes en un sistema silvopastoril</article-title>. <source>Pastos y Forrajes.</source> <volume>42</volume>, <fpage>57</fpage>&#x2013;<lpage>67</lpage>,</citation>
</ref>
<ref id="ref42">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>L&#x00F3;pez-Santiago</surname> <given-names>J. G.</given-names></name> <name><surname>Casanova</surname> <given-names>F.</given-names></name> <name><surname>Villanueva</surname> <given-names>G.</given-names></name> <name><surname>D&#x00ED;az</surname> <given-names>V. F.</given-names></name> <name><surname>Solorio</surname> <given-names>F. J.</given-names></name> <name><surname>Mart&#x00ED;nez</surname> <given-names>P.</given-names></name> <etal/></person-group>. (<year>2019</year>). <article-title>Carbon storage in a silvopastoral system compared to that in a deciduous dry forest in Michoaca&#x2019;n Mexico</article-title>. <source>Agrofor. Syst.</source> <volume>93</volume>, <fpage>199</fpage>&#x2013;<lpage>211</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10457-018-0259-x</pub-id></citation>
</ref>
<ref id="ref43">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Mart&#x00ED;nez-Garc&#x00ED;a</surname> <given-names>C. G.</given-names></name> <name><surname>Dorward</surname> <given-names>P.</given-names></name> <name><surname>Thair</surname> <given-names>R.</given-names></name></person-group> (<year>2012</year>). <article-title>Farm and socieconomic characteristics of small-holder milk producers and their influence on the technology adoption in Central M&#x00E9;xico</article-title>. <source>Trop. Anim. Health Prod.</source> <volume>44</volume>, <fpage>1199</fpage>&#x2013;<lpage>1211</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s11250-011-0058-0</pub-id></citation>
</ref>
<ref id="ref44">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Mazzetto</surname> <given-names>A. M.</given-names></name> <name><surname>Bishop</surname> <given-names>G.</given-names></name> <name><surname>Styles</surname> <given-names>D.</given-names></name> <name><surname>Arndt</surname> <given-names>C.</given-names></name> <name><surname>Brook</surname> <given-names>R.</given-names></name> <name><surname>Chadwick</surname> <given-names>D.</given-names></name></person-group> (<year>2020</year>). <article-title>Comparing the environmental efficiency of milk and beef production through life cycle assessment of interconnected cattle systems</article-title>. <source>J. Clean. Prod.</source> <volume>277</volume>:<fpage>124108</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.jclepro.2020.124108</pub-id></citation>
</ref>
<ref id="ref45">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Mena</surname> <given-names>V. E.</given-names></name> <name><surname>Andrade</surname> <given-names>H. J.</given-names></name></person-group> (<year>2021</year>). <article-title>Potencial de reducci&#x00F3;n de emisiones y captura de carbono en bosques y sistemas agroforestales con cacao en el Pac&#x00ED;fico colombiano</article-title>. <source>Rev. Biol. Trop.</source> <volume>69</volume>, <fpage>1252</fpage>&#x2013;<lpage>1263</lpage>. doi: <pub-id pub-id-type="doi">10.15517/rbt.v69i4.45927</pub-id></citation>
</ref>
<ref id="ref46">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Molina-Rivera</surname> <given-names>M.</given-names></name> <name><surname>Olea-Perez</surname> <given-names>R.</given-names></name> <name><surname>Galindo-Maldonado</surname> <given-names>F. A.</given-names></name> <name><surname>Arriaga-Jord&#x00E1;n</surname> <given-names>C. M.</given-names></name></person-group> (<year>2019</year>). <article-title>An&#x00E1;lisis de ciclo de vida de tres sistemas ganaderos tropicales en Campeche, M&#x00E9;xico: caso de estudio</article-title>. <source>Trop. Subtrop. Agroecosyst.</source> <volume>22</volume>, <fpage>127</fpage>&#x2013;<lpage>141</lpage>. doi: <pub-id pub-id-type="doi">10.56369/tsaes.2774</pub-id></citation>
</ref>
<ref id="ref47">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Nahed-Toral</surname> <given-names>J.</given-names></name> <name><surname>Valdivieso-P&#x00E9;rez</surname> <given-names>A.</given-names></name> <name><surname>Aguilar-Jim&#x00E9;nez</surname> <given-names>R.</given-names></name> <name><surname>C&#x00E1;mara-Cordova</surname> <given-names>J.</given-names></name> <name><surname>Grande-Cano</surname> <given-names>D.</given-names></name></person-group> (<year>2013</year>). <article-title>Silvopastoral systems with traditional management in southeastern Mexico: a prototype of livestock agroforestry for cleaner production</article-title>. <source>J. Clean. Prod.</source> <volume>57</volume>, <fpage>266</fpage>&#x2013;<lpage>279</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.jclepro.2013.06.020</pub-id></citation>
</ref>
<ref id="ref48">
<citation citation-type="book"><person-group person-group-type="author">
<name><surname>Navarrete</surname> <given-names>C.</given-names></name>
</person-group> (<year>2020</year>). <source>Los sistemas de producci&#x00F3;n de rumiantes en la Comarca Lagunera, M&#x00E9;xico: impacto ambiental, tendencias productivas y estrategias de mitigaci&#x00F3;n</source>. <comment>[Tesis Doctoral].</comment> <publisher-loc>Chapingo, M&#x00E9;xico</publisher-loc>: <publisher-name>Universidad Aut&#x00F3;noma de Chapingo</publisher-name>.</citation>
</ref>
<ref id="ref49">
<citation citation-type="other"><person-group person-group-type="author">
<collab id="coll12">OEIDRUS-Jalisco</collab>
</person-group> (<year>2017</year>). SAGARPA, OEIDRUS-Jalisco. Consultado en agosto de 2023. Disponible en</citation>
</ref>
<ref id="ref50">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Oldfield</surname> <given-names>E. E.</given-names></name> <name><surname>Eagle</surname> <given-names>A. J.</given-names></name> <name><surname>Rubin</surname> <given-names>R. L.</given-names></name> <name><surname>Rudek</surname> <given-names>J.</given-names></name> <name><surname>Sanderman</surname> <given-names>J.</given-names></name> <name><surname>Gordon</surname> <given-names>D. R.</given-names></name></person-group> (<year>2022</year>). <article-title>Crediting agricultural soil carbon sequestration</article-title>. <source>Science</source> <volume>375</volume>, <fpage>1222</fpage>&#x2013;<lpage>1225</lpage>. doi: <pub-id pub-id-type="doi">10.1126/science.abl7991</pub-id></citation>
</ref>
<ref id="ref51">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Ortiz</surname> <given-names>A. M.</given-names></name> <name><surname>Riascos</surname> <given-names>L. D.</given-names></name></person-group> (<year>2006</year>). <source>Almacenamiento y fijaci&#x00F3;n de carbono del sistema agroforestal cacao Theobroma cacao L y laurel Cordia alliodora (Ruiz &#x0026; Pav&#x00F3;n) Oken en la reserva ind&#x00ED;gena de Talamanca, Costa Rica. [Tesis de pregrado]</source>. <publisher-loc>San Juan de Pato (Colombia)</publisher-loc>: <publisher-name>Universidad de Nari&#x00F1;o</publisher-name>.</citation>
</ref>
<ref id="ref52">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>P&#x00E1;ez</surname> <given-names>E. M.</given-names></name> <name><surname>Corredor</surname> <given-names>E. S.</given-names></name> <name><surname>Fonseca</surname> <given-names>J. A.</given-names></name></person-group> (<year>2018</year>). <article-title>La huella h&#x00ED;drica y la huella de carbono: herramientas para estimar el impacto de la ganader&#x00ED;a bovina</article-title>. <source>Pensamiento y Acci&#x00F3;n.</source> <volume>24</volume>, <fpage>81</fpage>&#x2013;<lpage>92</lpage>,</citation>
</ref>
<ref id="ref53">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Pagiola</surname> <given-names>S.</given-names></name> <name><surname>Agostini</surname> <given-names>P.</given-names></name> <name><surname>Gobbi</surname> <given-names>J.</given-names></name> <name><surname>De Haan</surname> <given-names>C.</given-names></name> <name><surname>Ibrahim</surname> <given-names>M.</given-names></name> <name><surname>Murgueitio</surname> <given-names>E.</given-names></name> <etal/></person-group>. (<year>2004</year>). <source>Paying for biodiversity conservation services in agricultural landscapes</source>. <publisher-loc>Washington, DC</publisher-loc>: <publisher-name>The International Bank for Reconstructionand Development</publisher-name>.</citation>
</ref>
<ref id="ref54">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Parra</surname> <given-names>A. S.</given-names></name> <name><surname>Ramirez</surname> <given-names>D. Y. G.</given-names></name> <name><surname>Mart&#x00ED;nez</surname> <given-names>E. A.</given-names></name></person-group> (<year>2022</year>). <article-title>Silvopastoral systems ecological strategy for decreases C footprint in livestock Systems of Piedmont (Meta), Colombia</article-title>. <source>Braz. Arch. Biol. Technol.</source> <volume>66</volume>:<fpage>e23220340</fpage>. doi: <pub-id pub-id-type="doi">10.1590/1678-4324-2023220340</pub-id></citation>
</ref>
<ref id="ref55">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Prospero-Bernal</surname> <given-names>F.</given-names></name> <name><surname>Velarde-Guill&#x00E9;n</surname> <given-names>J.</given-names></name> <name><surname>Arriaga-Jord&#x00E1;n</surname> <given-names>C. M.</given-names></name></person-group> (<year>2019</year>). <source>La ganader&#x00ED;a mexicana ante el cambio clim&#x00E1;tico</source>. <publisher-loc>M&#x00E9;xico</publisher-loc>: <publisher-name>Universidad Aut&#x00F3;noma del Estado de M&#x00E9;xico</publisher-name>.</citation>
</ref>
<ref id="ref56">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Rice</surname> <given-names>P.</given-names></name> <name><surname>O'Brien</surname> <given-names>D.</given-names></name> <name><surname>Shalloo</surname> <given-names>L.</given-names></name> <name><surname>Holden</surname> <given-names>N. M.</given-names></name></person-group> (<year>2017</year>). <article-title>Evaluation of allocation methods for calculation of carbon footprint of grass-based dairy production</article-title>. <source>J. Environ. Manag.</source> <volume>202</volume>, <fpage>311</fpage>&#x2013;<lpage>319</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.jenvman.2017.06.071</pub-id></citation>
</ref>
<ref id="ref57">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Ru&#x00ED;z</surname> <given-names>N.</given-names></name> <name><surname>Carrera</surname> <given-names>F.</given-names></name> <name><surname>Villalobos</surname> <given-names>R.</given-names></name> <name><surname>Dur&#x00E1;n</surname> <given-names>L.</given-names></name></person-group> (<year>2021</year>). <source>Sistematizaci&#x00F3;n de la contribuci&#x00F3;n de los bosques modelo al cumplimiento de los objetivos de desarrollo sostenible</source>. <publisher-loc>Turrialba, Costa Rica</publisher-loc>: <publisher-name>CATIE</publisher-name>.</citation>
</ref>
<ref id="ref58">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Schettini</surname> <given-names>B. L. S.</given-names></name> <name><surname>Jacovine</surname> <given-names>L. A. G.</given-names></name> <name><surname>Oliveira Neto</surname> <given-names>S. N.</given-names></name> <name><surname>Torres</surname> <given-names>C. M. M. E.</given-names></name> <name><surname>Rocha</surname> <given-names>S. J. S. S.</given-names></name> <name><surname>Villanova</surname> <given-names>P. H.</given-names></name> <etal/></person-group>. (<year>2021</year>). <article-title>Silvopastoral systems: &#x00BF;how to use them for carbon neutral milk production?</article-title> <source>Carbon Manag.</source> <volume>12</volume>, <fpage>377</fpage>&#x2013;<lpage>384</lpage>. doi: <pub-id pub-id-type="doi">10.1080/17583004.2021.1951843</pub-id></citation>
</ref>
<ref id="ref59">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>S&#x00E1;nchez-Romero</surname> <given-names>R.</given-names></name> <name><surname>Mora-Ardila</surname> <given-names>F.</given-names></name> <name><surname>Val-Arreola</surname> <given-names>D.</given-names></name> <name><surname>Gonz&#x00E1;lez-Esquivel</surname> <given-names>C. E.</given-names></name></person-group> (<year>2022</year>). <article-title>Estimation of the forage potential of trees in silvopastoral systems of a dry tropical forest in Jalisco Mexico</article-title>. <source>Agrofor. Syst.</source> <volume>96</volume>, <fpage>129</fpage>&#x2013;<lpage>145</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10457-021-00704-9</pub-id></citation>
</ref>
<ref id="ref60">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll13">Secretar&#x00ED;a de Medio Ambiente y Recursos Naturales [SEMARNAT]</collab>
</person-group> (<year>2020</year>). &#x201C;<article-title>Contribuci&#x00F3;n determinada a nivel nacional. Actualizaci&#x00F3;n 2020</article-title>&#x201D; in <source>M&#x00E9;xico por el clima</source> (<publisher-loc>M&#x00E9;xico</publisher-loc>: <publisher-name>Gobierno de M&#x00E9;xico</publisher-name>).</citation>
</ref>
<ref id="ref61">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll14">Secretar&#x00ED;a de Medio Ambiente y Recursos Naturales [SEMARNAT]</collab>
</person-group> (<year>2021a</year>). <source>Lista de combustibles y sus poderes calor&#x00ED;ficos 2021 que se considerar&#x00E1;n para identificar a los usuarios con un patr&#x00F3;n de alto consumo, as&#x00ED; como los factores para determinar las equivalencias en t&#x00E9;rminos de barriles equivalentes de petr&#x00F3;leo</source>. <publisher-loc>M&#x00E9;xico</publisher-loc>: <publisher-name>Ciudad de M&#x00E9;xico</publisher-name>. Available at: <ext-link xlink:href="https://www.gob.mx/cms/uploads/attachment/file/619062/ListaCombustibles202126feb2021.pdf" ext-link-type="uri">https://www.gob.mx/cms/uploads/attachment/file/619062/ListaCombustibles202126feb2021.pdf</ext-link>.</citation>
</ref>
<ref id="ref001">
<citation citation-type="book"><person-group person-group-type="author">
<collab id="coll140">Secretar&#x00ED;a de Medio Ambiente y Recursos Naturales [SEMARNAT]</collab>
</person-group> (<year>2021b</year>). <source>Factor de emisi&#x00F3;n del sistema el&#x00E9;ctrico nacional 2020</source>. <publisher-loc>M&#x00E9;xico</publisher-loc>: <publisher-name>Ciudad de M&#x00E9;xico</publisher-name>. Available at: <ext-link xlink:href="https://www.gob.mx/cms/uploads/attachment/file/630693/AvisoFEE2020.pdf" ext-link-type="uri">https://www.gob.mx/cms/uploads/attachment/file/630693/AvisoFEE2020.pdf</ext-link>.</citation>
</ref>
<ref id="ref62">
<citation citation-type="other"><person-group person-group-type="author">
<collab id="coll15">Servicio de Informaci&#x00F3;n Agroalimentaria y Pesquera [SIAP]</collab>
</person-group>. (<year>2016</year>). Poblaci&#x00F3;n bovina de por Estado. Available at: <ext-link xlink:href="http://www.siap.gob.mx" ext-link-type="uri">www.siap.gob.mx</ext-link> (Accessed August 21, 2017).</citation>
</ref>
<ref id="ref63">
<citation citation-type="other"><person-group person-group-type="author"><name><surname>Tobar</surname> <given-names>D.</given-names></name> <name><surname>Vega</surname> <given-names>A.</given-names></name> <name><surname>Garc&#x00ED;a</surname> <given-names>E.</given-names></name> <name><surname>Sep&#x00FA;lveda</surname> <given-names>C.</given-names></name></person-group> (<year>2018</year>). <article-title>Balance de carbono en fincas ganaderas de Honduras. En las tres zonas del proyecto paisajes productivos. Tegucigalpa, Honduras: CATIE, GEF, PNUD, Gobierno de la Rep&#x00FA;blica de Honduras: Secretar&#x00ED;a de Recursos Naturales y Ambiente</article-title>.</citation>
</ref>
<ref id="ref64">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Thoma</surname> <given-names>G.</given-names></name> <name><surname>Jolliet</surname> <given-names>O.</given-names></name> <name><surname>Wang</surname> <given-names>Y.</given-names></name></person-group> (<year>2013</year>). <article-title>A biophysical approach to allocation of life cycle environmental burdens for fluid milk supply chain analysis</article-title>. <source>Int. Dairy J.</source> <volume>31</volume>, <fpage>S41</fpage>&#x2013;<lpage>S49</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.idairyj.2012.08.012</pub-id></citation>
</ref>
<ref id="ref65">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Tongwane</surname> <given-names>M.</given-names></name> <name><surname>Moeletsi</surname> <given-names>M.</given-names></name></person-group> (<year>2021</year>). <article-title>Provincial cattle carbon emissions from enteric fermentation and manure management in South Africa</article-title>. <source>Environ. Res.</source> <volume>195</volume>:<fpage>110833</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.envres.2021.110833</pub-id></citation>
</ref>
<ref id="ref66">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Triana-&#x00C1;ngel</surname> <given-names>N.</given-names></name> <name><surname>Burkart</surname> <given-names>S.</given-names></name></person-group> (<year>2021</year>). <source>Gestar cambios, transformar el sector: el caso de la Mesa Colombiana de Ganader&#x00ED;a Sostenible</source>. <publisher-loc>Wageningen, The Netherlands</publisher-loc>: <publisher-name>CGIAR</publisher-name>.</citation>
</ref>
<ref id="ref67">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Udawatta</surname> <given-names>R. P.</given-names></name> <name><surname>Walter</surname> <given-names>D.</given-names></name> <name><surname>Jose</surname> <given-names>S.</given-names></name></person-group> (<year>2022</year>). <article-title>Carbon sequestration by forests and agroforests: A reality check for the United States</article-title>. <source>Carbon Footprints.</source> <volume>2023</volume>, <fpage>1</fpage>&#x2013;<lpage>24</lpage>. doi: <pub-id pub-id-type="doi">10.20517/cf.2022.06</pub-id></citation>
</ref>
<ref id="ref68">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Uddin</surname> <given-names>M. E.</given-names></name> <name><surname>Aguirre-Villegas</surname> <given-names>H. A.</given-names></name> <name><surname>Larson</surname> <given-names>R. A.</given-names></name> <name><surname>Wattiaux</surname> <given-names>M. A.</given-names></name></person-group> (<year>2021</year>). <article-title>Carbon footprint of milk from Holstein and Jersey cows fed low or high forage diet with alfalfa silage or corn silage as the main forage source</article-title>. <source>J. Clean. Prod.</source> <volume>298</volume>:<fpage>126720</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.jclepro.2021.126720</pub-id></citation>
</ref>
<ref id="ref69">
<citation citation-type="book"><person-group person-group-type="author">
<name><surname>Vega</surname> <given-names>A.</given-names></name>
</person-group> (<year>2016</year>). <source>An&#x00E1;lisis de herramientas para la estimaci&#x00F3;n de gases de efecto invernadero (GEI) y su aplicaci&#x00F3;n en sistemas de producci&#x00F3;n doble prop&#x00F3;sito en fincas ganaderas de la cuenca del r&#x00ED;o Jes&#x00FA;s Mar&#x00ED;a, Costa Rica</source>. <comment>[Tesis de maestr&#x00ED;a].</comment> <publisher-loc>Turrialba (Costa Rica)</publisher-loc>: <publisher-name>CATIE</publisher-name>.</citation>
</ref>
<ref id="ref70">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Velarde-Guill&#x00E9;n</surname> <given-names>J.</given-names></name> <name><surname>Arndt</surname> <given-names>C.</given-names></name> <name><surname>G&#x00F3;mez</surname> <given-names>C. A.</given-names></name></person-group> (<year>2022</year>). <article-title>Carbon footprint in Latin American dairy systems</article-title>. <source>Trop. Anim. Health Prod.</source> <volume>54</volume>, <fpage>1</fpage>&#x2013;<lpage>7</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s11250-021-03021-6</pub-id></citation>
</ref>
<ref id="ref71">
<citation citation-type="other"><person-group person-group-type="author">
<name><surname>Villanueva</surname> <given-names>C.</given-names></name>
</person-group> (<year>2022</year>). <article-title>An&#x00E1;lisis de las emisiones de gases de efecto invernadero en fincas productoras de leche de Costa Rica. [Tesis de doctorado]. [Santiago de Compostela (Espa&#x00F1;a)]: Universidad de Santiago de Compostela</article-title>.</citation>
</ref>
<ref id="ref72">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Villanueva-L&#x00F3;pez</surname> <given-names>G.</given-names></name> <name><surname>Mart&#x00ED;nez-Zurimendi</surname> <given-names>P.</given-names></name> <name><surname>Casanova-Lugo</surname> <given-names>F.</given-names></name> <name><surname>Ram&#x00ED;rez-Av&#x00ED;les</surname> <given-names>L.</given-names></name> <name><surname>Monta&#x00F1;ez-Escalante</surname> <given-names>P. I.</given-names></name></person-group> (<year>2015</year>). <article-title>Carbon storage in livestock systems with and without live fences of <italic>Gliricidia sepium</italic> in the humid tropic of M&#x00E9;xico</article-title>. <source>Agrofor. Syst.</source> <volume>89</volume>, <fpage>1083</fpage>&#x2013;<lpage>1096</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s10457-015-9836-4</pub-id></citation>
</ref>
<ref id="ref73">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>He</surname> <given-names>X.</given-names></name> <name><surname>Sunday Adebayo</surname> <given-names>T.</given-names></name> <name><surname>Kirikkaleli</surname> <given-names>D.</given-names></name> <name><surname>Umar</surname> <given-names>M.</given-names></name></person-group> (<year>2021</year>). <article-title>Consumption-based carbon emissions in Mexico: an analysis using the dual adjustment approach</article-title>. <source>Sustain. Product. Consump.</source> <volume>27</volume>, <fpage>947</fpage>&#x2013;<lpage>957</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.spc.2021.02.020</pub-id></citation>
</ref>
<ref id="ref74">
<citation citation-type="book"><person-group person-group-type="author">
<name><surname>Yunga</surname> <given-names>S. A.</given-names></name>
</person-group> (<year>2020</year>). <source>An&#x00E1;lisis comparativo del c&#x00E1;lculo de huella de carbono por litro de leche producido, entre peque&#x00F1;os y medianos productores que emplean pr&#x00E1;cticas ganaderas convencionales y peque&#x00F1;os y medianos productores que emplean pr&#x00E1;cticas de ganader&#x00ED;a clim&#x00E1;ticamente inteligente</source>. <comment>[Tesis de Maestr&#x00ED;a].</comment> <publisher-loc>Quito (Ecuador)</publisher-loc>: <publisher-name>Universidad Andina Sim&#x00F3;n Bolivar</publisher-name>.</citation>
</ref>
</ref-list>
</back>
</article>