The Effects of Land Management Policies on the Environment and People in Low- and Middle-Income Countries: A Systematic Review.

内容摘要

Background: Widespread land degradation is driven by unsustainable land use and human pressures, and is accelerating climate change and biodiversity loss. Access to land is also essential for livelihoods and well-being, particularly in low- and middle-income countries (L&MICs). Urgent and inclusive land management interventions are needed to mitigate climate impacts, preserve biodiversity, and support vulnerable communities. Governments and international organisations are increasingly promoting land management interventions, such as establishing protected areas, granting land rights and decentralising land management and monitoring. These efforts aim to enable the realisation of several of the Sustainable Development Goals (SDGs) and the Kunming-Montreal Global Biodiversity Framework (KMGBF). The environmental and human development impacts of these interventions, and especially their potential interactions, remain under-researched. This synthesis of the literature can help to inform policy and research decisions in these contexts. Objectives: The purpose of this systematic review was to appraise and synthesise evidence of the effects of three types of land management interventions (community-based or decentralised land management and monitoring, land rights, and protected areas) on environmental and human well-being outcomes in L&MICs. We examined how these effects vary across geographical and social contexts. We also discussed the barriers, enablers, and trade-offs between environmental and human well-being outcomes that impact the effectiveness of the specified interventions. Lastly, we aimed to synthesise cost evidence of included projects. Search methods: The search of included studies was based on the evidence gathered in the Climate Change and Biodiversity Evidence Gap Map (CCB EGM, Marion et al., 2024). The CCB EGM displayed the available rigorous evidence on the effects of climate change and biodiversity interventions on environmental and human well-being outcomes in L&MICs. The systematic search of studies was conducted in March 2024. Selection criteria: From the CCB EGM, we focused on impact evaluations of projects which covered three types of land management interventions in L&MICs: (1) community-based or decentralised land management and monitoring; (2) land rights; and (3) protected areas. In this review, we considered studies published after 2000 that reported intervention effects on both environmental and human well-being outcome groups, aiming to identify possible trade-offs, synergies, and unintended consequences of these land management interventions. Data collection, and analysis: We identified 64 papers representing 58 unique studies. These impact evaluations assessed 60 projects across 26 L&MICs, reporting effects on both environmental and human well-being outcomes. Two independent reviewers conducted the data extraction and risk of bias assessments of projects' effects. With the available evidence, we conducted meta-analyses to synthesise effectiveness findings for comparable outcomes. For the set of included projects, we searched for additional qualitative information to identify barriers, enablers, unintended consequences and trade-offs that can affect project effectiveness, and for cost-related evidence that can inform the cost-effectiveness of these projects. Limitations of this review include: 1) the CCB EGM's search only covered studies published up to March 2024; (2) the CCB EGM's search only used terms in English; (3) the meta-analyses conducted in this review were most often based on a small number of estimates; and 4) half of the included quantitative evidence was judged to have a high risk of bias. Main results: The available evidence looking at the environmental and human well-being effects of these three land management interventions is sparse. Quantitative and qualitative evidence suggests that these interventions represent potentially effective strategies to promote shifts towards sustainable use of land resources and improvements in human livelihoods. These interventions can, however, result in significant trade-offs between environmental health and human welfare. The three interventions reviewed present dissimilar levels of evidence, mostly focused on community-based or decentralised land management and monitoring. Nearly all these projects took place in Africa, Latin America and the Caribbean, and East Asia and the Pacific. Available evidence on final environmental outcomes, such as biodiversity, climate adaptation and mitigation measures, is limited. Decentralised land management and monitoring increased income, possibly driven by improvements in the governance of natural resources and greater adoption of improved practices and technology. There is evidence that these interventions initiated a shift away from agricultural and forestry harvesting, as they promote forest preservation and development. Land rights led to a small increase in agricultural and livestock productivity, greater diversification of income sources and investments in natural resources or conservation. In turn, protected areas slightly reduced deforestation and improved agricultural and livestock productivity, as well as income and assets. Aligning interventions with existing communities' economic activities and values can create virtuous cycles for the sustainability of land and people's livelihoods. Knowledge-sharing and collaboration opportunities often enabled intervention success, whereas a lack of clarity, governance and funding structures were identified as barriers to intervention success. Conservation interventions can potentially and inadvertently lead to deforestation, land degradation, and biodiversity loss if the local population lacks the incentive to adopt these new practices. Increased wildlife from conservation efforts can also come at the cost of decreased food security and damaged properties, potentially affecting people's livelihoods. The extent and quality of cost evidence were generally insufficient to enable a comprehensive analysis of cost-effectiveness across included land management interventions. The review, however, identified useful insights from four well-documented cases. Authors' conclusions: Environmental and human well-being outcomes are closely linked, and evaluating them in isolation risks overlooking their interacting mechanisms. Interventions should be grounded in local socio-economic and ecological contexts, allow for continuous learning and adjustment, and prioritise inclusive, fair and equitable approaches. More rigorous, theory-informed evaluations that report on both environmental and human well-being are needed. Future research should also better integrate cost-effectiveness analyses from the outset and track long-term and equity-related outcomes. Using agile evaluation methods and remote-sensing data can help close evidence gaps and improve decision-making in complex and dynamic environments. Navigating trade-offs while creating opportunities for virtuous cycles between environmental protection and human well-being through land management interventions in low- and middle-income countries. The review in brief The evidence reporting on both the environmental and human well-being effects of land management interventions is limited. The findings suggest that these interventions result in small positive effects on improved natural resource use and management, productivity and income. Effects on biodiversity, climate mitigation and other longer-term human well-being outcomes remain inconclusive. What is this review about? The accelerating rise in global temperature and depletion of land ecosystems and fauna are highly interconnected, increasingly threatening livelihoods and human well-being in L&MICs. Land management policies aim to conserve, preserve and restore natural resources and ecosystems, while also offering long-term and sustainable economic opportunities for local communities. This review synthesised the available evidence reporting on both the environmental and human well-being effects of three land management policies: community-based or decentralised land management and monitoring, land rights, and protected areas. What is the aim of this review? This Campbell Systematic Review examined the effects of three land management interventions, appraising and synthesising the available evidence. We also explored the barriers, enablers, and trade-offs that can affect these projects, and aimed to synthesise cost evidence of included projects. What are the main findings of this review? What studies are included? We included impact evaluations of land management interventions which reported on both environmental and human well-being effects in L&MICs. We relied on evidence gathered in the Climate Change and Biodiversity Evidence Gap Map (CCB EGM, Marion et al., 2024), identifying 60 land management interventions in 26 L&MICs. Across the three intervention types, the evidence base is limited, especially on the effects of protected areas. Almost half of the evidence was assessed as having a high risk of bias. We also identified 112 documents providing qualitative information, mostly of high or moderate quality, on factors affecting the successful implementation of these projects. Additionally, we found reliable cost evidence for four of the included projects. How has this intervention worked? The effects varied across the three land management interventions. The evidence shows that decentralised land management and monitoring increased income, likely due to better natural resource governance and adoption of improved practices. This intervention type also led to a modest decline in land area used for agriculture and forestry, indicating a shift toward forest preservation. We also observed some improvements in intermediate environmental and human well-being outcomes from land rights interventions. We found that aligning with existing community livelihoods and providing knowledge-sharing and collaboration opportunities contributed to project success in some cases. Lack of clarity and governance, as well as inadequate funding structures, were identified as barriers to project success. We also found that project efforts to conserve the environment can inadvertently result in environmental degradation if local communities lack the incentive to adopt new practices. What do the findings of this review mean? The extent of the current evidence base remains small. Further rigorous quantitative and qualitative analyses are essential to understand the effects of these interventions and to design effective land management policies. While there can be important trade-offs to consider when implementing land management interventions in L&MICs, they can also support virtuous cycles of environmental protection and human well-being. Reporting projects’ cost data can also provide crucial insight into the variability of expenditure needed across different contexts and enhance our understanding of their value for money. How up-to-date is this review? The search for studies was completed in March 2024. This Campbell Systematic Review was published in 2026.