The first article on this topic was published in a renowned scientific journal in 1983. After that, the number of published articles followed an increasing trend, with a significant rise especially after 2015 (Figure 2). Citations have followed a similar upward trend, in line with the number of published articles. Citation data: citing articles = 7,389, times cited = 8,058, average per item = 2,984 (Web of Science, 2024).

A total of 204 authors who have published at least one article on this topic were identified. The most prolific contributors in the area of pine use on degraded lands were Lucian Dinca and Cristinel Constandache (5 articles each), and John Stanturf (4 articles), reflecting a strong focus on ‘degraded land’ terminology in Romanian research. In contrast, the most productive authors in studies focusing on carbon stocks in pine stands were primarily from Finland and Spain—such as Seppo Kellomäki (18 articles), Keli Peltola (14), Miren del Río (13), and Ricardo Ruiz-Peinado (13 articles)—highlighting regional specialization. Although the largest number of articles originated from institutions in the USA and China, these contributions were more widely distributed among a larger pool of authors with fewer publications each.

The most well-represented countries are the USA (72 articles), China (41 articles), Spain (30 articles), Canada (16 articles), and Germany (15 articles) (Table 1).

The countries of origin of the authors who have published articles on this topic can be grouped into five clusters: the first cluster includes England, Ecuador, Belgium, France, and the Czech Republic; the second cluster includes Spain, Brazil, Mexico, Sweden, Italy, Poland, and Norway; the third cluster includes China, Russia, and Turkey; the fourth cluster includes the USA, Iran, Argentina, and Sri Lanka; the fifth cluster includes Germany, Chile, and South Korea (Figure 3).

The most representative institutions where authors publishing on this topic are active include: Chinese Academy of Science (with 18 articles), United State Department of Agriculture (with 17 articles), United States Forest Service (with 17 articles), Consejo Superior de Investigaciones Cientificas (with 10 articles), University of Wisconsin Madison (with 9 articles) and University of Wisconsin System (with 9 articles).

Articles on this topic have been published in 306 journals, with the highest number of articles appearing in: Forest Ecology and Management (25 articles), Forests (16 articles) and Land Degradation & Development (11 articles). However, when considering total link strength, the top three journals in the ranking are: Forest Ecology and Management, Catena, and Geoderma (Table 2).

The journals can be grouped into six clusters: Cluster 1: Applied Soil Ecology + Agriculture, Ecosystems & Environment + Ecological Engineering; Cluster 2: Journal of Hydrology + Ecological Indicators + Science of the Total Environment + Agricultural and Forest Meteorology; Cluster 3: Forest Ecology and Management + Land Degradation + Ambio; Cluster 4: Restoration Ecology + Ecological Applications + New Forests + Plant and Soil; Cluster 5: Catena + European Journal of Forest Research + Geoderma + Biodiversity and Conservation + Land Degradation & Development; Cluster 6: Forests + iForest-Biogeosciences and Forestry + Bioenergy Research + Scientific Papers Series E-Land (Figure 4). Journals were grouped into clusters using co-citation analysis and the VOSviewer clustering algorithm based on their bibliographic coupling strength (VOS Viewer, 2010).

The most frequently used keywords are forest, afforestation, nitrogen, and plantations, highlighting the central themes in the literature on pine-related restoration. The keywords are grouped into four distinct clusters, each reflecting different thematic emphases in the field. The first cluster includes 16 words, such as forest, nitrogen, management, organic carbon, and sequestration, indicating a strong focus on soil nutrient dynamics and carbon management in forested systems. This cluster underscores the ecological processes underpinning carbon sequestration and nutrient cycling in pine-based restoration efforts. The second cluster consists of 15 words, including biodiversity, growth, restoration, reforestation, land, and succession. These terms suggest a broader ecological restoration narrative, where biodiversity recovery and vegetative succession are central outcomes of reforestation, particularly with pine species, especially when planted in their native range or in admixtures. The third cluster, comprising 10 words such as biomass, land use, plantations, Scots pine, and climate change, reflects the intersection of land-use change, biomass productivity, and climate mitigation potential—highlighting pine plantations’ role in sustainable land management. Lastly, the fourth cluster includes 7 keywords like pine, soil, erosion, and impact, pointing to the role of pine species in controlling land degradation, particularly through soil stabilization and erosion reduction. Together, these clusters provide a multifaceted view of how pine species contribute to degraded land recovery, linking soil health, biodiversity, carbon cycling, and climate resilience. This clustering helps structure the ongoing scientific conversation and identifies integrated themes across ecological and management domains (Table 3 and Figure 5).

While in the 2012–2013 period the keywords used were plantations, vegetation, reforestation, and dynamics, in the years 2014–2016, the most used were nitrogen, land-use, restoration, and growth. In more recent years (2017–2020), the most common keywords have been biodiversity, communities, pine plantations, and climate change (Figure 6).

Plantations with different pine species (pure or mixed with deciduous trees) were established on degraded or abandoned lands, contributing to the restoration of the ecosystem and biodiversity. Restoring and preserving forest carbon (C) stocks in subtropical and tropical regions is an effective way to capture atmospheric CO₂ (Griscom et al., 2020; Koch and Kaplan, 2022). Afforesting degraded soils is essential for ecosystem recovery (Lamb et al., 2005; Coban et al., 2022). Reforestation with loblolly pine on degraded lands can restore soil carbon stocks to levels similar to subtropical natural forests within 30 years (Veloso et al., 2018).

Beyond carbon sequestration, pine plantations contribute to a suite of ecological functions that make them valuable tools in the restoration of degraded landscapes. Their roles in soil stabilization, hydrological regulation, microclimate amelioration, and biodiversity enhancement support ecosystem recovery and resilience (Chirino et al., 2006; Martín-Peinado et al., 2016; Cifuentes-Croquevielle et al., 2020).

Soil stabilization and erosion control: Pine root systems, particularly those of species like Pinus halepensis and P. pinaster, are effective in stabilizing soils on slopes and erosion-prone areas (Danjon et al., 2005; Pérez-Rodríguez et al., 2007). Their dense root mats reduce surface runoff and enhance soil cohesion, critical in restoring degraded hillsides and preventing landslides or gully formation.

Hydrological regulation: Pine plantations can influence hydrological processes through canopy interception, evapotranspiration, and improved infiltration. In semi-arid and Mediterranean environments, Pinus halepensis plantations have shown mixed effects, with some studies indicating reduced runoff and better water infiltration due to improved ground cover, while others highlight potential water consumption trade-offs (Voltas et al., 2015; Vicente et al., 2018). Site-specific planning is thus essential to avoid adverse water balance impacts.

Microclimate improvement: Pines contribute to the amelioration of local microclimates by providing shade, reducing temperature extremes, and increasing air humidity (Castro et al., 2002; Gómez-Aparicio et al., 2008). This can foster the re-establishment of understory vegetation and soil microbial activity, creating favorable conditions for broader ecosystem development.

Biodiversity enhancement through admixtures: Although monoculture pine plantations often support lower biodiversity than natural forests, mixed-species plantations or those managed for structural heterogeneity can enhance habitat value (Carnus et al., 2006). Integrating broadleaved species such as Quercus, Populus, or native shrubs with pine increases vertical and horizontal complexity, promoting faunal and floral diversity (Barbaro and Rossi, 2006; Arnold and Larsson, 2017; Constandache et al., 2016). For instance, mixtures of Pinus sylvestris with native species in Europe have been shown to support higher bird and insect diversity compared to pure stands (Felton et al., 2010).

Ecological legacy and resilience: Over time, pine plantations can serve as ecological scaffolds—facilitating the return of native species, improving soil fertility, and enabling transitions toward more diverse forest systems. Their adaptability to poor soils and harsh conditions makes them particularly useful as pioneer species in restoration trajectories (Parrotta et al., 1997; Ruiz-Jaen and Aide, 2005).

In sum, the ecological benefits of pine plantations go beyond carbon to encompass multiple ecosystem functions vital for landscape rehabilitation. When designed with ecological principles and long-term goals, pine plantations can be a cornerstone of integrated restoration strategies.

Most of the publications on this topic are articles (90%), distributed across 30 research areas, of which the most representative are Environmental Science, Ecology, Forestry, and Agriculture.

The most prominent research areas and journals are directly linked to the causes and consequences of land degradation and the outcomes of pine plantations on different land categories. Moreover, the keywords used in recent years align with modern trends in research on this topic and with management methods for pine stands. As some researchers point out, an analysis of the keywords used by authors reflects research trends (Onan et al., 2016). In the early years (2012–2013), the research focus was primarily on practical aspects of land recovery, reflected in keywords such as plantations, vegetation, reforestation, and dynamics. During the mid-period (2014–2016), studies increasingly addressed ecological processes, with prominent terms like nitrogen, land-use, restoration, and growth. More recently (2017–2020), the attention has shifted toward broader environmental concerns, with keywords including biodiversity, communities, pine plantations, and climate change, indicating a growing integration of ecological and climate-related themes into pine-related land restoration research. The keywords chosen for the article titles are among the top keywords used by the authors who published on this topic: pine ranks 10th, reforestation 12th, and management 11th. However, afforestation ranks 1st, and forest 2nd, highlighting the crucial role that afforestation and forests play in improving degraded lands. Other top keywords include plantations (4th), dynamics (7th), and carbon (8th). Keywords related to land use also occupy a special place (14th and 15th), and if combined, would likely rank 2nd.

The number of published articles as well as citations has increased significantly after 2015. The growing trend of published articles, observed in other bibliometric studies (Liu et al., 2019), also applies to the topic of pines on degraded lands. This phenomenon can be explained by two main factors: a recent substantial increase in the number of journals and scientific publications, along with a growing level of interest among researchers in this topic. Furthermore, the average annual number of scientific publications is expected to increase, driven by the growing demand for strategies that enhance carbon uptake, particularly in forest and grassland ecosystems, given their significant role in reducing greenhouse gas emissions (Ma et al., 2025). The increase in publications reflects the growing attention given to pines, especially in regions such as the Mediterranean Region, the Alps, and the USA. Our analysis identified authors from 66 countries across five continents who have contributed to this topic (Figure 7). We included only 23 countries out of 66, because we have considered only the most representative clusters (those with at least 5 countries).

Out of a total of 187 known pine species (World Flora Online, 2024), our bibliographic study identified 38 species (20% of the total number of pine species) for which articles have been published regarding afforestation and carbon stocks, with Pinus banksiana Lamb. being the most cited. The most commonly used species for afforestation of degraded lands, especially in Europe, has been the black pine (Pinus nigra Arn.), known as a species with modest requirements regarding climatic and soil conditions (Șofletea and Curtu, 2007; Vlad et al., 2019), with good results in halting soil erosion and landscape degradation. Various pine species (Pinus sylvestris L., Pinus cembra L., Pinus ponderosa Douglas ex C. Lawson) have been used both for afforestation of degraded lands (Untaru et al., 2008; Silvestru-Grigore et al., 2018) and on other land categories outside their natural range or to replace poorly productive stands (Enescu and Dănescu, 2013).

Since the chosen topic also refers to pines in mountainous areas, some review articles address this component (Vallauri et al., 2002; Hofstede et al., 2002). Other articles focus on plant inventory methods, such as monitoring (Traci and Untaru, 1986), remote sensing (Mapuru et al., 2023), stand structure in specific geographical regions (Thanasis et al., 2007), or the evolution of plantations under different climatic and soil conditions (Constandache et al., 2024). Also, some articles focus on the examination of scientific literature about agroforestry practices and their role in enhancing agricultural productivity (Enescu et al., 2025) as well as the influence of climatic factors on health and sustainability (Bratu et al., 2025; Tudor et al., 2023). Review articles analyzing the influence of climate change on pine plantations on degraded lands are also well represented (Vlad et al., 2019).

Since this topic concerns areas of afforested degraded lands, it is natural that the authors come from countries with significant afforested areas, such as the USA, China, and Germany. Regarding the journals in which articles on this topic have been published, many have titles including terms such as forest, ecology, environment (e.g., Forest Ecology and Management, Forests, Restoration Ecology, Science of the Total Environment, Agriculture Ecosystems & Environment) or include restoration, aligning with the primary scientific fields discussed above.

Afforestation with pines on degraded lands serves as an effective strategy for soil stabilization, nutrient retention, and landscape restoration. The results indicate that pine plantations enhance soil organic carbon (SOC) levels, particularly in severely degraded and mined lands. Studies from Poland and Estonia demonstrate that afforested lands with Scots and black pine show a marked increase in carbon sequestration over time, aligning with findings from previous research on carbon recovery in forested ecosystems (Woś et al., 2022; Karu et al., 2009). Moreover, pine species such as Mongolian Scots pine have proven particularly effective in semi-arid regions for mitigating desertification and improving soil carbon content. In most European countries, afforestation of degraded lands began at the end of the 19th century, with the main goal of conserving soil and landscapes. Pines were widely used in afforestation efforts in Greece, France, and Hungary. Afforestation was primarily carried out with black pine (Pinus nigra ssp. nigra and P. nigra ssp. laricio), with plantations needed to stop soil erosion and landscape degradation in hilly areas. This species is much more tolerant to maritime influences, such as salt-laden winds, than Scots pine (Pinus sylvestris), which is why it often grows closer to the sea. In Mediterranean Region, during the second half of the 20th century, many large reforestation projects were conducted in the south of Europe (Villar-Salvador, 2016). Several reforestation programs were undertaken in degraded areas where different pine species were planted, focused on reducing erosion and increase the forest productivity (Pausas et al., 2004).

In France, in the southwestern Alps region Haute-Provence, at 120 years after the first tree plantings, the plant communities are still early seral assemblages for the most part, with Austrian black pine occurring alone in the canopy. In contrast, most of the marly soils have physically recovered part of their total depth, with layers of fragmented and altered material equal to 50 cm, but their structure and chemical fertility are still poor (Vallauri et al., 2002). Pinus nigra Arnold var. austriaca has been widely used in reforestations in Greece. The use of P. nigra to restore the degraded ecosystems around Mt. Olympus was deemed as successful (Thanasis et al., 2007).

In Hungary, black pine, being quite drought-resistant and heat-tolerant, was used to improve lands characterized by dolomitic and sandy soils, where vigorous stands resulted (Tamas, 2003). In Bulgaria, the first afforestation efforts date from 1884 to 1887, when anti-erosion afforestation was undertaken on about 4,000 hectares. Forest plantations were established, predominantly of coniferous tree species [Pinus sylvestris L., Pinus nigra Arn., Pseudotsuga menziesii (Mirb.) Franco and so on] (Aleksandrov and Tonchev, 2021).

In the Southern United States, by the end of the 20th century, there were 32 million acres of pine plantations on cutover forest land and degraded agricultural land, and this region is now the woodbasket of the world (Fox et al., 2004).

In the Himalayan sub-tropical region, Chir pine (Pinus roxburghii), is the predominant tree species (Champion and Seth, 1968; Forest Survey of India, 2019), distributed within an altitude range of 450–2,300 m above mean sea level, covering nearly all major valleys and slopes in the region (Forest Survey of India, 2019) having the ability to mitigate soil erosion, improve soil quality and promote sustainable ecosystems (Razafindrabe et al., 2010).

In tree plantations in the Ecuadorian Andes, in extreme climatic and site conditions and soils developed in recent volcanic ashes, pine-based forestry programs are still promoted, using arguments such as the future demand for timber, the social acceptance of exotic species, and the possible ecological benefits of forest plantations in general (Hofstede et al., 2002).

Environmental factors, especially temperature and precipitation, significantly influence the results of studies on the behavior of pine trees in different areas. Temperature affects growth and development, while precipitation influences water availability and, therefore, the health and vitality of trees (Köse et al., 2025; Ramírez-Valiente et al., 2021) having an impact in biomass accumulation and carbon stock (Wu et al., 2025). In regions experiencing moderate increases in precipitation, carbon stocks may be sustained as long as moisture availability does not constrain vegetation growth, while elevated temperatures, can negatively affect biomass accumulation and carbon uptake, acting as a stress factor that may limit soil organic carbon storage (Murphy et al., 2025). Spatial and temporal variations in these factors can lead to different growth responses among pine populations, even within the same species (Zhao et al., 2024).

The impact of pine plantations cannot be generalized but should be evaluated case by case while care is taken in implementing plantations until more knowledge is obtained about the effects on the ecosystem as a whole, especially considering their ecological importance.

In conclusion, pine plantations can be a valuable way for both carbon sequestration and ecological reconstruction of degraded lands, but their effectiveness depends on the composition of the forest, the management practices applied and the intervention of damaging factors, requiring permanent long-term monitoring.

Many published articles refer to various pine species and their relationship with carbon stocks (Wang et al., 2012), to growth dynamics using allometric equations with different variables, and to the effect of silvicultural practices on plantations and carbon stocks (del Río et al., 2017).

A key focus of the reviewed studies was the assessment of carbon sequestration capacity of various pine species. The results indicate that different pine species contribute differently to carbon stocks depending on site conditions, forest management practices, and climatic variables (Navarro-Cerrillo et al., 2022; Wang et al., 2013; Węgiel and Polowy, 2020). Additionally, some authors used the cluster related to the “forest floor” to estimate biomass, including both total carbon and litter carbon storage, while assessing the effects of tree species (Huang et al., 2020). Their findings indicated that pine species exhibited higher carbon stocks in both the forest floor and soil organic layers (Usuga et al., 2010). The comparison between pure pine stands and mixed-species forests suggests that while pine plantations accumulate significant aboveground biomass carbon, mixed forests may provide a better balance of belowground and aboveground carbon storage (Rodríguez de Prado et al., 2023). Furthermore, thinning interventions were found to have variable impacts on carbon sequestration, influenced by several interacting factors. These include thinning intensity (Deng et al., 2019; del Río et al., 2017), tree species (Navarro-Cerrillo et al., 2022; Pohjola and Valsta, 2007), stand age (Lull et al., 2024; Powers et al., 2012), and site conditions such as soil type, elevation, and climate (Murariu et al., 2021; Crișan et al., 2024). Heavier thinning often promotes individual tree growth and increases carbon allocation to fewer, larger trees, potentially enhancing long-term biomass carbon stock (Deng et al., 2019; del Río et al., 2017). However, it can also temporarily reduce total ecosystem carbon due to biomass removal (Bravo-Oviedo et al., 2015; Ruiz-Peinado et al., 2013). Soil carbon responses are equally variable: thinning has been shown to increase soil organic carbon in some pine species and regions (Settineri et al., 2018), while in others, the changes were negligible or absent (Erkan et al., 2023; Ruiz-Peinado et al., 2016). Other relevant factors include the presence of understory vegetation, post-thinning regeneration, and whether the harvested biomass is stored in long-lived wood products (Alfaro-Sánchez et al., 2015; del Río et al., 2017). Therefore, the impact of thinning on carbon storage is highly context-dependent and must be evaluated within specific ecological and silvicultural frameworks.

Most articles analyzed environmental conditions and their effects on pine plantations, their structure, yield, and functions, to provide insights on estimating the success of reforestation or ecological restoration and on selecting optimal planting, maintenance, and stand management techniques about the species used and the environmental conditions.

Despite the benefits, challenges associated with pine afforestation must be acknowledged. The ecological impact of pine plantations, particularly regarding biodiversity, soil properties, and long-term sustainability, requires careful management. This suggests that afforestation efforts should consider the trade-offs between rapid biomass accumulation and long-term soil carbon stability.

Additionally, the selection of pine species is crucial for afforestation success. While Scots pine and black pine have been extensively used due to their adaptability to poor soils and harsh climates, other species such as P. taeda and P. radiata have demonstrated high productivity in specific regions.

After 1950, afforestation with coniferous species was widespread in the lower forest belt, which is outside their natural range. Now, due to the already advanced age of the artificial plantations established in the 1960s and 1970s, as well as the initiated processes of intensive degradation, their great ecological and economic value requires taking timely decisions on their future management (Aleksandrov and Tonchev, 2021).

For example, P. hartwegii exhibits more than 70% mortality due to water stress (Flores et al., 2021). Under such conditions, pine species will face adaptation difficulties and will not achieve the intended ecological reconstruction and protection goals. In recent years, there has been growing concern about restoring degraded ecosystems with pines and hardwood species, with various models being promoted to optimize their structure at acceptable costs (Vlad et al., 2019).

Future research should explore the long-term impacts of different pine species on soil condition and carbon cycling to optimize afforestation strategies.

The bibliometric analysis indicates an increasing trend in research on pines and carbon sequestration, yet gaps remain. Future studies should focus on the long-term monitoring of carbon stocks in pine afforestation projects, integrating remote sensing and modeling techniques to improve carbon estimation accuracy. Additionally, comparative studies between pine afforestation and other land-use strategies (e.g., agroforestry, mixed-species plantations) are needed to determine the most effective approaches for maximizing carbon sequestration and ecosystem resilience.

Moreover, climate change projections should be incorporated into afforestation planning, as changing precipitation patterns and temperature extremes may affect pine growth, survival, and carbon sequestration potential (Vasile et al., 2017; Mustățea et al., 2022; Tudose et al., 2023a, 2023b). Research on adaptive management strategies, including species selection, thinning regimes, and soil amendments, will be critical for ensuring the long-term viability of pine afforestation on degraded lands.

Studies on artificially planted pine forests analyzing their structure, yield and function are needed to provide answers about site suitability for each tree species used and for the estimation of reforestation success (Thanasis et al., 2007). Future research should focus on innovative techniques for ecological restoration and regeneration of pine forests, measures to adapt them to climate change, the impact of forest ecosystem management practices on degraded lands’, carbon storage potential, and the effectiveness of different pine species under various ecological conditions.

This study highlights how the authors of existing studies analyze the impact of environmental factors on pine forests, using modeling, statistical analysis or experimental approaches. These methods help to understand how variations in environmental factors, such as temperature and precipitation, affect the state and evolution of pine forests, especially those on degraded lands, but also their ecosystem functions, in the context of climate change. In conclusion, pine forests are sensitive to changes in temperature and precipitation, and these factors can influence their distribution, growth, and health. Understanding these relationships is essential for predicting future forest dynamics and developing effective management strategies in the context of climate change.

There are also some gaps and limitations of our study: Limited geographic scope – While the study covers a broad range of regions where pine plantations have been used for degraded lands restoration, some areas with significant afforestation efforts may be underrepresented due to data availability constraints. Lack of long-term data – Many studies focus on short- to medium-term effects of pine afforestation, while the long-term ecological impacts, including biodiversity shifts and soil nutrient cycling, remain less explored. Exclusion of unpublished data and local case studies – The review primarily relies on published scientific literature indexed in databases such as Web of Science. Important local studies, government reports, and unpublished research may be missing. Lack of socioeconomic analysis – While the study focuses on ecological and carbon sequestration benefits, it does not comprehensively address economic and social aspects, such as cost-effectiveness, local community involvement, and policy implications of pine plantations on degraded lands.

To address these limitations, future studies should: Incorporate long-term ecological research/monitoring of pine plantations; Integrate socio-economic factors into afforestation analysis; Investigate the ecological trade-offs between pine afforestation and native species conservation.