Developing effective REDD+ strategies that respect the Cancun safeguards and help to achieve countries’ development objectives and contribute to meeting their many international commitments requires careful planning. This includes identifying where and how REDD+ actions (policies and measures) can achieve the greatest benefits, both for climate change mitigation and for other priorities such as biodiversity conservation. Strategy development needs both planning approaches that take account of potential ecosystem services from forests and the feasibility of individual REDD+ actions, and a foundation of scientifically sound information on how these are distributed across the landscape.
Key scientific challenges for supporting sound decisions on forest and land use include:
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understanding the distribution and conservation importance of species other than vertebrates, especially in highly complex tropical forests;
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identifying specific ecosystem types that are distinct and potentially in need of conservation or other management action (critical for country commitments to the CBD’s Aichi Biodiversity Targets, which emphasize the importance of “unique ecosystems” and of ensuring that all ecosystems are appropriately protected);
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understanding disturbance and regeneration processes, and their implications for restoration and how biodiversity, ecosystem function, and ecosystem services recover;
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identifying the factors determining climate resilience of forests and how these relate to biodiversity
New advances in remote sensing, such as identifying functional variation in tropical forests (Asner et al. Airborne laser-guided imaging spectroscopy to map forest trait diversity and guide conservation. Science. 2017) give us new ways to look at tropical forests, and identify and understand their variability. This functional variation could act as an indicator for tree biodiversity. Hence these advances have the potential to address some of these challenges and improve the information available to support decision making on forest and land use. Asner’s team used airborne (not satellite) hyperspectral sensors to gather high-resolution data on seven functional traits of rainforest canopy leaves in the Amazon-Andes region of Peru. These traits are potentially linked to species composition and ecosystem function. They include leaf nutrient (N, P, Ca) and water content, which underpin photosynthesis, primary production and plant responses to climate change and foliar defence compounds, such as polyphenols and lignin. The team then modelled functional diversity on the basis of these traits and mapped forest functional classes. The results can help understand functional variation in a highly complex ecosystem that is notoriously difficult to sample from the ground and where many species are poorly known or new to science. The authors suggest that their approach may link more closely to ecosystem function than results from traditional forest inventories do.
With further investigation of the links between canopy traits and diversity in groups other than trees, these approaches could help to solve the first two of the challenges listed. Another high priority is to expand remote-sensing work on functional traits and diversity to areas of known land-use history. This would improve our understanding of spatial patterns of disturbance and of how diversity and function recover after disturbance. They are also useful for monitoring and addressing human impacts on forests in more meaningful terms than simply the presence or absence of tree cover alone. Remotely sensed data on tropical forest functional diversity can contribute to modelling that improves our overall understanding forest ecosystems.
The UN-REDD Programme supports partner countries in integrating biodiversity and other forest benefits into their planning, and in developing country approaches to safeguards and safeguards information. There is a clear and growing need for incorporating high-quality information on forest biodiversity and function in decision-making on land use. Remote-sensing approaches have a tantalizing potential to meet some of this need, allowing us to develop and regularly update new indicators of the status of biodiversity throughout the forest. In principle these could contribute to a safeguards information system, combined with other data to help illustrate the impacts of REDD+ policies and measures in retaining, restoring and managing forests. However, to improve its usefulness for safeguards information, planning and decision-making for REDD+, remote sensing data needs to be combined with ecological understanding, and then transformed into products that can be clearly communicated and are of practical use.
