BIODIVERSITY RESEARCH Quantifying mammal biodiversity co-benefits in certified tropical forests Rahel Sollmann 1,2 *, Azlan Mohamed 2 ,J€ urgen Niedballa 2 , Johannes Bender 2 , Laurentius Ambu 3 , Peter Lagan 4 , Sam Mannan 4 , Robert C. Ong 5 , Andreas Langner 6 , Beth Gardner 1† and Andreas Wilting 2 1 Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, USA, 2 Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany, 3 Sabah Wildlife Department, 5th Floor, B Block, Wisma MUIS, 88100 Kota Kinabalu, Sabah, Malaysia, 4 Sabah Forestry Department, Locked Bag 68, 90009 Sandakan, Sabah, Malaysia, 5 Forest Research Centre, Sabah Forestry Department, P.O. Box 1407, 90715 Sandakan, Sabah, Malaysia, 6 European Commission, Joint Research Centre, Institute for Environment and Sustainability, Via Enrico Fermi 2749, I - 21027 Ispra, Italy *Correspondence: Rahel Sollmann, Department of Wildlife, Fish and Conservation Biology, University of California Davis, 1088 Academic Surge, One Shield Ave, Davis, CA 95616, USA. E-mail: rsollmann@ucdavis.edu † Present address: School of Environmental and Forest Sciences, University of Washington, Seattle, WA 98195, USA. ABSTRACT Aim Financial incentives to manage forests sustainably, such as certification or carbon storage payments, are assumed to have co-benefits for biodiversity con- servation. This claim remains little studied for rain forest mammals, which are particularly threatened, but challenging to survey. Location Sabah, Malaysia, Borneo. Methods We used photographic data from three commercial forest reserves to show how community occupancy modelling can be used to quantify mam- malian diversity conservation co-benefits of forest certification. These reserves had different management histories, and one was certified by the Forest Ste- wardship Council. Results Many threatened species occupied larger areas in the certified reserve. Species richness, estimated per 200 9 200-m grid cell throughout all reserves, was higher in the certified site, particularly for threatened species. The certi- fied reserve held the highest aboveground biomass. Within reserves, above- ground biomass was not strongly correlated with patterns of mammal richness (Spearman’s rho from 0.03 to 0.32); discrepancies were strongest along reserve borders. Main conclusions Our approach provides a flexible and standardized tool to assess biodiversity and identify winners of sustainable forestry. Inferring pat- terns of species richness from camera-trapping carries potential for the objec- tive designation of high conservation value forest. Correlating species richness with aboveground biomass further allows evaluating the biodiversity co-benefits of carbon protection. These advantages make the present approach an ideal tool to overcome the difficulties to rigorously quantify biodiversity co-benefits of forest certification and carbon storage payments. Keywords Borneo, carbon payment, community occupancy model, forest stewardship council, REDD+, Southeast Asia, sustainable forestry. INTRODUCTION Owing to their exceptional species richness, the destruction of tropical rain forests causes extreme biodiversity losses (e.g. Brook et al., 2003; Gardner et al., 2009). In Southeast Asia, deforestation rates have been higher than in other tropical regions (Miettinen et al., 2011). Protected areas, although a cornerstone of conservation, are not sufficient to halt the loss of biodiversity and need to be combined with sustainable use of natural resources (Sodhi et al., 2010; Edwards et al., 2014; Struebig et al., 2015). Sustainable use of forests can only be achieved if maintaining forests provides financial benefits to offset the profits offered by plantations (Butler et al., 2009). In this context, two global initiatives have been set up. First, sustainability certification schemes, particularly the Forest Stewardship Council (FSC), allow producers to sell forest products at higher market prices, compensating for the higher costs and reduced timber yields of sustainably DOI: 10.1111/ddi.12530 ª 2017 John Wiley & Sons Ltd http://wileyonlinelibrary.com/journal/ddi 317 Diversity and Distributions, (Diversity Distrib.) (2017) 23, 317–328