High Carbon Stock forests provide co-benefits for tropical biodiversity

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Deere NJ, Guillera-Arroita G, Baking EL, et al. High Carbon Stock forests provide co-benefits for tropical biodiversity. J Appl Ecol. 2017;00:1–12.

Conservation efforts focused on protecting forests using carbon-based policies also benefit mammal diversity, new research at the University of Kent has found. To help mitigate the effects of climate change, policies have been developed across the world to reduce greenhouse gas emissions through avoided deforestation. Much of this deforestation is caused by large-scale agriculture and extractive industries in developing tropical countries. The UN’s Reducing Emissions from Deforestation and forest Degradation (REDD+) framework, and, more recently, the High Carbon Stock (HCS) Approach, aim to identify and conserve forest areas that retain a lot of carbon, which would otherwise be released into the atmosphere if felled, therefore justifying protection. Major agricultural companies, such as those growing oil palm, are now using these carbon mechanisms as part of global commitments to ‘zero deforestation’. In the past it has been assumed that protecting forests to prevent carbon release is also beneficial for biodiversity in the area too. However, previous studies have proved inconclusive. To tackle this assumption, a team of researchers from the Durrell Institute of Conservation and Ecology (DICE) at the University of Kent, have been undertaking wildlife surveys in the forests of Borneo, in an area undergoing conversion to oil palm. Lead researcher, Nicolas Deere, gathered a comprehensive dataset of mammals derived from camera-trap images and combined this with high-resolution satellite imagery to show that areas designated for protection under carbon policies were also rich in endangered mammals. In particular, the study confirmed that no correlation between carbon and biodiversity was evident when globally-available carbon maps were used. However, when high-resolution maps were used to map carbon resources, areas of high carbon were clearly seen to support the most mammal species. This relationship was driven by species of conservation concern such as orangutan and clouded leopards, suggesting that mammals vulnerable to deforestation and forest degradation will benefit the most from carbon policies. The findings have important implications for policymakers in business, government and non-government organisations, by confirming that REDD+ and HCS approaches to designate land for protection have strong potential for biodiversity conservation in the oil palm sector. Nicolas was supported in his research by Dr Matthew Struebig and Dr Zoe Davies at the University of Kent and colleagues in the universities of Newcastle, Melbourne, Malaysia Sabah, as well as the Zoological Society of London. The paper, titled ‘High carbon stock forests provide co-benefits for tropical biodiversity’, has been published in the Journal of Applied Ecology.

1. Carbon-based policies provide powerful opportunities to unite tropical forest conservation with climate change mitigation. However, their effectiveness in delivering biodiversity co-benefits is dependent on high levels of biodiversity being found in high carbon areas. Previous studies have focussed solely on the co benefits associated with Reducing Emissions from Deforestation and forest Degradation (REDD+) over large spatial scales, with few empirically testing carbon-biodiversity correlations at management unit scales appropriate to decision-makers. Yet, in development frontiers, where most biodiversity and carbon loss occurs, carbon-based policies are increasingly driven by commodity certification schemes, which are applied at the concession level.
2. Working in a typical human-modified landscape in Southeast Asia, we examined the biodiversity value of land prioritised via application of REDD+ or the High Carbon Stock (HCS) approach, the emerging land-use planning tool for oil palm certification. Carbon stocks were estimated via low-and high-resolution datasets
derived from global or local-level biomass. Mammalian species richness was predicted using hierarchical Bayesian multispecies occupancy models of camera-trap data from forest and oil palm habitats.
3. At the community level, HCS forest supported comparable mammal diversity to control sites in continuous forest, while lower carbon strata exhibited reduced species occupancy.
4. No association was found between species richness and carbon when the latter was estimated using coarse-resolution data. However, when using high-resolution, locally validated biomass data, diversity demonstrated positive relationships with carbon for threatened and disturbance-sensitive species, suggesting sensitivity of co-benefits to carbon data sources and the species considered.
5. Policy implications. Our work confirms the potential for environmental certification and Reducing Emissions from Deforestation and forest Degradation to work in tandem with conservation to mitigate agricultural impacts on tropical forest carbon stocks and biodiversity. Successful implementation of both approaches could be used to direct development to low carbon, low biodiversity areas in
tropical countries.