In the urgent race to combat climate change, a groundbreaking new study underscores the critical role of young secondary forests in carbon sequestration, revealing that protecting these nascent woodlands may deliver optimal climate mitigation benefits. While much global attention has traditionally focused on conserving mature and intact forests due to their massive carbon stores and biodiversity value, recent findings spotlight young secondary forests as exceptionally potent carbon sinks. These rapidly growing forests not only absorb significant carbon dioxide but do so within vital policy timelines, offering a dynamic and immediate natural climate solution.
The research introduced novel global Aboveground Carbon (AGC) accumulation curves at an unprecedented 1-kilometer resolution, charting forest regrowth trajectories over a century of natural regeneration. These curves, when combined with current maps of forest stand age and available restoration land, empower precise predictions of carbon removal potential from any starting point of forest age. For example, if 800 million hectares of restorable forest begin regenerating simultaneously in 2025, they could collectively sequester up to 20.3 billion megagrams of carbon by 2050. However, the study warns that even a marginal restoration delay—by five or ten years—could curtail this potential by approximately 25% or 50%, respectively, underscoring urgency.
Such findings point to a nuanced carbon dynamics landscape: established young secondary forests outperform new regrowth substantially. By 2050, these forests can provide up to eight times the carbon removal per hectare compared to new regenerating stands. This immediate and amplified carbon sink capability fills a crucial gap given that freshly regenerating forests undergo a lag phase before they reach peak carbon absorption capacity. Consequently, policies delaying reforestation projects risk severely undermining global carbon sequestration goals by missing this window of maximal carbon uptake.
Secondary forests, often overlooked in climate policy frameworks, are now recognized as indispensable natural climate allies. Beyond their superior carbon accumulation rates, young secondary forests embody a more assured mitigation potential than nascent regeneration, which faces existential threats. Factors like the absence of local seed sources, limited seed dispersal agents, or climatic constraints such as rising temperatures inhibiting germination imperil initiation success in new forest stands. Consequently, protecting and managing already established secondary forests emerges as a safer and more predictable strategy in the climate mitigation arsenal.
Despite their promise, these young forests face increasingly severe anthropogenic pressures. Across Latin America, the probability of secondary forest loss dwarfs their persistence by a factor of ten, illustrating the fragile and transient nature of these carbon-rich refuges. In the Brazilian Amazon, studies reveal that half of secondary forests vanish within eight years post-establishment, while in more humid Costa Rican forests, the average clearance age hovers around twenty years. This widespread clearance erodes carbon removal gains rapidly and necessitates policy shifts prioritizing immediate protection for these vulnerable young stands.
The carbon dividend of protecting secondary forests is unequivocal. For instance, an 8-year-old secondary forest in the Brazilian Amazon could remove 36% more atmospheric carbon by 2030 compared to a newly regenerated equivalent. Similar trends are evident in Costa Rica, where a 20-year-old secondary forest demonstrates a 65% greater carbon removal rate by 2030. Protecting such forests effectively locks in potential climate benefits both by maintaining ongoing peak carbon removals and by preventing the release of stored carbon through deforestation, a double climate action benefit seldom highlighted in existing policies.
Unfortunately, current carbon market structures and forestry project methodologies inadequately incentivize the protection or improved management of young secondary forests. Most carbon credit frameworks demand a minimum stand age—usually a decade post-clearance—before projects qualify, effectively excluding forests younger than ten years. Moreover, improved management projects predominantly apply to logged forests and represent only a fraction of secondary forest areas. This systemic omission prevents recognition and reward for early-stage forest carbon dynamics and hampers funding flows to protect these vital ecosystems.
Recognition of natural forest regeneration as a legitimate climate mitigation strategy demands rigorous criteria adherence. Additionality, requiring evidence that forests are at risk of conversion or unlikely to regenerate without intervention, is notably difficult to demonstrate for existing secondary forests. Nonetheless, the advent of dynamic baseline approaches offers promise by comparing project areas against non-project controls with temporal specificity. Durability—the permanence of sequestered carbon—is another critical factor. While the study’s AGC model is empirically grounded and accounts for mortality, it remains conservative by excluding carbon pools in dead wood and soil, and it does not yet encompass increasing disturbance risks posed by climate change.
The study also highlights data and methodological challenges inherent in global regeneration assessments. Current global datasets on forest age and biomass often fail to distinguish between naturally regenerating and production or plantation forests, adding uncertainty to lead projections. Furthermore, estimates do not yet incorporate future forest cover change dynamics driven by climate, land use, or disturbance regimes. Nevertheless, the analysis reveals that, on a per-hectare basis, protecting secondary forests during their peak carbon removal phase often yields on average a 10% increment in carbon removal rates over initiating new regeneration, with some locations showing up to an 820% increase. This striking disparity advocates for a dual strategy: protecting existing secondary forests while designating additional lands for new regeneration.
Addressing these pressing knowledge gaps, the researchers identify several avenues for future investigation. One critical element lies in socio-economic contexts. Many secondary forests exist on lands supporting rural and indigenous communities whose livelihoods depend on forest resources and shifting cultivation. Climate finance mechanisms and restoration initiatives must judiciously balance carbon goals with social equity and human rights to avoid unintended negative impacts. Inclusion of local knowledge and needs into forest management can promote intersecting benefits encompassing biodiversity, ecosystem services, and rural employment, thus achieving more sustainable outcomes.
Biomes beyond forests, notably savannas and grasslands, present another layer of complexity. Although included in the data, their carbon removal potentials are modest and incremental due to slow tree establishment rates and frequent fire disturbances. These ecosystems follow distinct carbon cycling processes and require customized mitigation approaches separate from forest-focused regeneration strategies. Caution is warranted when extrapolating forest-centric solutions to these non-forested landscapes to avoid ineffective or counterproductive interventions.
Data biases also warrant refinement for more precise and globally representative outputs. The majority of plot data underpinning the AGC curves derive from northern temperate zones, leaving tropical and southern hemisphere forests underrepresented despite their critical importance in global carbon cycling. Enhanced field data collection in these regions, coupled with synergistic integration of remote sensing technology, could bridge spatial and temporal gaps, delivering more robust models that better serve policy decisions worldwide.
To enrich future carbon removal assessments, expanding beyond aboveground biomass to integrate soil carbon and other carbon reservoirs is imperative. Soils can store significant carbon volumes, and their inclusion would yield more comprehensive sequestration estimates. Correspondingly, accounting for climate change effects on carbon removal rates and carbon stock durability, especially under increasing disturbance intensities, is critical for realistic long-term projections. Additionally, understanding variation in initial disturbance types—such as selective logging, fire severity, or land degradation levels—could elucidate establishment success and growth trajectories, informing tailored management practices.
Intriguingly, the research recognizes that inconsistencies in forest stand age reporting, such as even-aged versus uneven-aged stand definitions, may inject noise into growth analyses. This nuance highlights the need for localized studies and refined inventory methodologies to calibrate global models, ensuring interventions are ecologically appropriate and context-specific. Tailored analyses remain essential to optimize both forest carbon dynamics and broader ecosystem resilience at site or regional scales.
Conclusively, this compelling body of evidence lays bare the paramount importance of timely action to conserve and manage young secondary forests. Their unique carbon sequestration dynamics offer a climate mitigation lever that is both immediate and scalable. Protecting these forests preserves peak carbon removal capacity, reduces the likely release of stored carbon upon deforestation, and amplifies global mitigation outcomes. Integrating these insights into carbon markets, policy frameworks, and restoration strategies could markedly enhance climate action effectiveness during critical mid-century targets.
The study’s synthesis forms a clarion call: in the climate fight, protecting young secondary forests is not merely advantageous—it is essential. Embracing this shifting paradigm demands retooling of finance mechanisms, targeted conservation efforts, and equitable community engagement to unlock their full, timely climate potential. Such integrated approaches promise not only to reinvigorate carbon sinks but also to advance sustainable development pathways, delivering enduring benefits for both planetary and human well-being.
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Subject of Research: Carbon sequestration potential and climate mitigation value of young secondary forests through natural regeneration.
Article Title: Protect young secondary forests for optimum carbon removal.
Article References:
Robinson, N., Drever, C.R., Gibbs, D.A. et al. Protect young secondary forests for optimum carbon removal. Nat. Clim. Chang. (2025). https://doi.org/10.1038/s41558-025-02355-5
Image Credits: AI Generated
