Achieving global climate change mitigation goals relies simultaneously on reducing greenhouse gas emissions and increasing carbon sequestration by terrestrial ecosystems (Masson-Delmotte et al., 2021). Since methods to remove other greenhouse gases are still in the early stages of development, most anthropogenic removals focus on carbon dioxide (CO₂) removal (Shukla et al., 2022; Caldecott and Johnstone, 2024). At the same time, relatively few studies consider not only CO₂ but also CH₄ and N₂O emissions (Shvidenko et al., 2025).

In addition to providing logs for the timber industry, forests are recognized for their pivotal role in regulating the global carbon cycle and maintaining biodiversity (Ninan and Inoue, 2013; Costanza et al., 2017; Bratu et al., 2024). Typically, the resource and environmental functions of forests compete with each other. Simultaneously addressing the challenges of forestry development and expanding the role of forests in regulating the carbon balance remains an unresolved scientific and practical issue (Chiti et al., 2026).

This problem is particularly acute in economies where clear-cutting is a prevalent forest management practice. Russia, the subject of our study, is one striking example (Shvarts et al., 2023). Regulation of the national forestry system has conflicting objectives and does not actually address the full range of challenges facing forest use in the country. The current measures of state forest policy are not leading to an improvement in the condition of forests, but rather to their degradation (Sohag et al., 2023). The depth of these contradictions is particularly evident in issues related to achieving national climate change mitigation goals.

Notwithstanding the superior capacity of deciduous tree species in accumulating soil organic carbon in comparison to conifers in nascent plantations (Hüblov and Frouz, 2021), the stipulations of the Russian Federal Agency for Forest Management (Rosleskhoz) in fact constrain reforestation in Russia to mainly coniferous species. The logic behind this decision does not take into account either the higher rate of carbon accumulation in both small-leaved tree species such as birch (Betula spp.), aspen (Populus tremula), black alder (Alnus glutinosa), and broad-leaved tree species such as oak (Quercus spp.), linden (Tilia spp.), and ash (Fraxinus spp.), especially during the 40–45 years of their most fast growth rate, or their importance for biodiversity conservation (Korotkov, 2017). As a result, reforestation in Russia is mainly done by planting coniferous species, principally pine (Pinus sylvestris) and spruce (Picea abies), the same as in many other parts of Europe in the past (Felton et al., 2010; Paillet et al., 2010; Liu et al., 2018).

The rules in effect at the 1st March of 2025¹ require that at least 30% of tree plantings use container-grown seedlings, despite the fact that such material approximately four times more expensive than bareroot seedlings² (Shvarts et al., 2025b). The motivation behind this decision is to restore forests with species that are highly valuable for subsequent economic use, even on forest land that is not expected to be used for logging in the coming decades—there is only around 15% of State Forest Fund lands is under lease in forestry purposes (Shvarts et al., 2025a). The share of lease for forestry purposes of State Forest Fund lands stable during 2020s. Clearly, this does not consider that the traditional coniferous monocultures planted after clear-cutting and fires in Siberia will be replaced by small-leaved trees. These forest stands will predominantly be birches (Betula spp.) and to a lesser extent, gray alder (Alnus incana) and aspen (Populus tremula), with a probability of at least a 90% (Bondarev et al., 2015).

The forest carbon projects currently being developed in Russia for reforestation with coniferous species are often essentially meaningless. The carbon sequestration flows they generate are lower than in the baseline scenario with natural regrowth of deciduous forests (Korotkov et al., 2021), at least during the first 40–50 years. Only when the forest stand is over 50 years old does carbon accumulation in Pinus sylvestris crops become higher than during spontaneous overgrowth (Shanin et al., 2022). A separate issue in this regard is the use of single-species tree plantations, which ignores well-known research findings confirming that mixed plantations often significantly outperform them in terms of carbon absorption rates (Chomel et al., 2014; Liu et al., 2018). In addition, the role of non-coniferous species in timber markets is also growing, despite their relatively lower demand in the past (Lauri et al., 2021).

Our study aims to develop a strategy for changing and improve forest management in Russia. This strategy will preserve and sustainably reproduce forests while achieving national goals for mitigating the effects of climate change. The results of our study expand the application of modern assessments of the carbon budget of Russian forests (i.e., Shvidenko et al., 2025) and efforts to improve state forest policy (Leskinen et al., 2020; Dobrynin et al., 2021; Shvarts et al., 2023, 2025a; Pyzhev, 2025).

The logic of our research stems from recognizing the importance of protecting and use secondary forests that could provide up to 8-fold more carbon removal per hectare than new regrowth of coniferous (Waring et al., 2020; Robinson et al., 2025). It is also taken into account that, conversion from coniferous to broadleaved trees in currently forested areas can provide cooling for summer hot extremes (Yao et al., 2025). The resulting shifts from conifer to broadleaf deciduous forest dominance allow forests to sequester more carbon and are more resistant to burning (Black et al., 2026).

To identify peculiarities and differences in carbon absorption trajectories between coniferous and deciduous species in Russian forests, we use ground-based observations of woody plant growth parameters across country's major geographical regions over a sufficient time period from the reference book (Shvidenko et al., 2008).

According to the Paris Agreement, the maximum timeframe for a climate project is 15 years, with the possibility of two extensions. Therefore, comparisons are made for forests that have been planted for 15, 30, and 45 years, respectively.

To estimate the annual rate of carbon sequestration by specific species, we only considered phytomass carbon accumulation data for the most typical stands. In some cases, data corresponding to designated age classes (e.g., 15 or 30 years) was used directly. In other cases, the average annual phytomass growth of the nearest age step was multiplied by the number of missing years.

Calculations of the annual average carbon accumulation rate (r) were made according to the formula:

where c is accumulated carbon in the phytomass of existing plantations, t·ha⁻¹, a is the age class that corresponds to the observation (e.g., 20, 40 years). The conversion factor 44/12 is used to convert units into tons of CO₂-equivalent.

We use literature data to show differences in the cost of implementing reforestation projects.

Our study considers two macro-regions: European Russia and Siberia. The most typical and widespread habitats for growing stands were identified for each species.

For comparison, calculations are presented for the two most common site indexes in Russian forests: II and III. Exceptions include Pinus sylvestris and Larix sibirica in Siberian forests because data on these species are only presented for site indexes II and III, respectively.

Our findings (Figures 1, 2) demonstrate that deciduous tree species, such as birch (Betula spp.) in the European part of Russia and aspen (Populus tremula) in Siberia, are significantly more effective and attractive solutions for increasing carbon sequestration capacity than coniferous tree species, such as pine (Pinus sylvestris) and spruce (Picea abies) and, to a lesser extent, larch (Larix sibirica).

Nevertheless, the Russian forestry authorities traditionally ignore these deciduous species in favor of less effective coniferous monocultures for reforestation. Previous studies have demonstrated that investments in carbon units obtained from growing black alder (Alnus glutinosa) are 5.5 times more effective than those obtained from pine and 4.6 times more effective than those obtained from spruce (Nesterenko et al., 2025). The corresponding yield estimates of carbon units during silver birch (Betula pendula) cultivation compared to pine and spruce are 4.5 and 3.7 times higher, respectively (Table 1).

Therefore, it can be concluded that the capacity of the main secondary deciduous species (birch, alder and aspen) consistently and effectively sequesters more carbon than the dominant species in boreal and temperate forests, such as pine, spruce, and, to a lesser extent, larch.

Although there is a widespread perception among decision makers in Russia that, due to the huge area and absorbing capacity of forests, the country should not significantly “invest” in the decarbonization of industry, housing and communal services, the real picture of the dynamics of the carbon balance in the forests and natural ecosystems of Russia are not so promising and positive (Bashmakov, 2024; Romanovskaya and Korotkov, 2024; Shvarts et al., 2025a; Teben'kova et al., 2020). However, this requires to take in account real carbon sequestration capacities of different tree species in different types of forests, especially those that are not rented for industrial timber harvesting. The task demands a profound reform of national forest policy to create incentives for climate-smart forest management.

We argue that the following measures could be the first steps toward achieving this goal.

We propose supplementing the existing reforestation rules by allowing:

At the same time, the following additional restrictions should be introduced:

Further discussions should analyze long-term carbon sequestration and storage dynamics of conifers vs. deciduous species at different age stages and in different air humidity conditions, advantages and disadvantages of different mixed species compositions, climate resilience and disturbance resistance of different mixed species systems, risks under increasing fire frequency.

Our research demonstrates the advantages of amending Russia's national forest policy regarding reforestation regulations. Our keystone suggestion is: if forest restoration will take in account advantages of deciduous trees in carbon sequestration during first 40–50 years after self-restoration, it will increase carbon sequestration capacity during the whole 100–120 years cycle due to full use of capacities of both deciduous (up to 45–50 years) and coniferous trees (after 50 years) by the most effective way—just as natural forest succession cycle. We emphasize the shortcomings of the entrenched practice of reforestation that disregards the benefits of promoting natural regeneration of deciduous species. Not only does reforestation with monoculture plantings of coniferous tree species fail to bring the expected benefits to the forestry industry, but it also diminishes the potential to increase the carbon sequestration capacity of Russian forests and reduces biodiversity. Using deciduous species for reforestation potentially could solve this problem without requiring significant amount of additional resources and partly redirect budget resources to fire-prevention measures and to fire-fighting infrastructure.