Protected areas reduce deforestation and degradation and enhance woody growth across African woodlands

Effect of reserve protection level and governance on tree cover loss and gain

Terrestrial protected areas are essential for biodiversity conservation, yet it is not fully understood when and how different types of protected areas are most effective in achieving specific conservation objectives. We assessed the impact of reserves on tree cover loss and gain through a case study in Tasmania, Australia. We considered varying protection levels (strict, where human activities are restricted, and multiple use) and governance types (public and private). We used a counterfactual matching approach to compare tree cover loss and gain between reserves and matched unprotected areas from 2004 to 2021. We accounted for forest policy changes, environmental covariates, and human pressures to reduce placement bias. We also characterized reserves by size, governance, management, and vegetation and compared covariates inside and outside reserves to define baseline conditions. Reserves established from 2004 to 2016 were overall 75.4% less likely to have lost tree cover and 16.0% more likely to have had tree cover gain compared with controls. Patterns of loss and gain varied by protection level and governance type. Multiple-use reserves were as effective as reserves in which human activities were more restricted. Privately managed reserves contributed to tree cover growth, and public reserves helped avoid loss. This highlights reserves' distinct contributions to conservation targets, with private reserves allowing for growth and restoration and public reserves acting as stable anchor points. Our results emphasize the importance of having a diverse array of protected areas to enhance the resilience of reserve networks. We advocate for adaptive regional measures and robust monitoring to achieve global ecological targets.

Fragmentation in patchy ecosystems: a call for a functional approach

Habitat fragmentation is a major threat to biodiversity, but existing literature largely ignores naturally patchy ecosystems in favor of forests, where deforestation creates spatially distinct fragments. Here, we use savannas to highlight the problems with applying forest fragmentation principles to spatially patchy ecosystems. Identifying fragmentation using landscape functionality, specifically connectivity, enables better understanding of ecosystem dynamics. Tools and concepts from connectivity research are well suited to identifying barriers other than vegetation structure contributing to fragmentation. Opportunities exist to improve fragmentation mapping by combining remote-sensing data with field measurements related to connectivity to empirically test whether landscapes are functionally fragmented. Advancements in deep learning and increasingly accessible data open many possibilities for comprehensive maps of fragmentation.

Environmental and social impacts of carbon sequestration

Climate change requires major mitigation efforts, mainly emission reduction. Carbon sequestration and avoided deforestation are complementary mitigation strategies that can promote nature conservation and local development but may also have undesirable impacts. We reviewed 246 articles citing impacts, risks, or concerns from carbon projects, and 78 others related to this topic. Most of the impacts cited focus on biodiversity, especially in afforestation projects, and on social effects related to avoided deforestation projects. Concerns were raised about project effectiveness, the permanence of carbon stored, and leakage. Recommendations include accounting for uncertainty, assessing both mitigation and contribution to climate change, defining permanence, creating contingency plans, promoting local projects, proposing alternative livelihoods, ensuring a fair distribution of benefits, combining timber production and carbon sequestration, ensuring sustainable development and minimizing leakage. A holistic approach that combines carbon sequestration, nature conservation, and poverty alleviation must be applied. The potential occurrence of negative impacts does not invalidate carbon projects but makes it advisable to conduct proper environmental impact assessments, considering direct and indirect impacts, minimizing the negative effects while maximizing the positive ones, and weighing the trade-offs between them to guide decision-making. Public participation and transparency are essential. Integr Environ Assess Manag 2024;20:1812-1838. © 2024 SETAC.