Anticipated climate and land‐cover changes reveal refuge areas for Borneo's orang‐utans

Abstract

Habitat loss and climate change pose a double jeopardy for many threatened taxa, making the identification of optimal habitat for the future a conservation priority. Using a case study of the endangered Bornean orang-utan, we identify environmental refuges by integrating bioclimatic models with projected deforestation and oil-palm agriculture suitability from the 1950s to 2080s. We coupled a maximum entropy algorithm with information on habitat needs to predict suitable habitat for the present day and 1950s. We then projected to the 2020s, 2050s and 2080s in models incorporating only land-cover change, climate change or both processes combined. For future climate, we incorporated projections from four model and emission scenario combinations. For future land cover, we developed spatial deforestation predictions from 10 years of satellite data. Refuges were delineated as suitable forested habitats identified by all models that were also unsuitable for oil palm -a major threat to tropical biodiversity. Our analyses indicate that in 2010 up to 260 000 km 2 of Borneo was suitable habitat within the core orang-utan range; an 18-24% reduction since the 1950s. Land-cover models predicted further decline of 15-30% by the 2080s. Although habitat extent under future climate conditions varied among projections, there was majority consensus, particularly in northeastern and western regions. Across projections habitat loss due to climate change alone averaged 63% by 2080, but 74% when also considering land-cover change. Refuge areas amounted to 2000-42 000 km 2 depending on thresholds used, with 900-17 000 km 2 outside the current species range. We demonstrate that efforts to halt deforestation could mediate some orang-utan habitat loss, but further decline of the most suitable areas is to be expected given projected changes to climate. Protected refuge areas could therefore become increasingly important for ongoing translocation efforts. We present an approach to help identify such areas for highly threatened species given environmental changes expected this century.

Impending extinction crisis of the world’s primates: Why primates matter

“…Interactions between climate change and other extinction drivers also need to be considered. For instance, projections of land-cover change show that the Bornean orangutan might lose 15 to 30% of its habitat by 2080, mainly due to deforestation and oil palm agriculture, but when coupled with climate change, even more habitat is likely to become unsuitable ( 80 ). Additionally, more frequent and severe climate change can induce floods, droughts, fires, hurricanes, and El Niño–Southern Oscillation events ( 81 ) that can affect the food supply available to primate populations, with negative impacts on health, fertility, and mortality ( 82 ).…”

“…It includes taking advantage of global telecommunication systems and wireless Internet, satellite- and airborne-based imagery, drone technology, ever more powerful handheld devices (for example, smart phones and tablets), and camera traps (Supplementary Text) ( 120 , 128 ). Combined with geographic information system and ground surveys, some of this technology has been used in evaluating sustainable land-use spatial planning and human-primate conflicts [for example, Javan gibbons ( Hylobates moloch )] ( 129 ) and in providing case-by-case assessments of species vulnerability to climate change, as shown for Borneo’s orangutans (Supplementary Text) ( 80 ). These same technologies can also be used by local citizen scientists for species and habitat monitoring, thus enhancing the effectiveness of mitigation measures ( 128 ).…”

Characteristic of Orangutan Habitat in Coal Mining Rehabilition Area in East Kalimantan, Indonesia

“…The main threats to the orangutan survival are habitat loss, habitat degradation, forest fires, habitat fragmentation, illegal hunting, lack of awareness, and climate change (Meijaard et al 2001; . Ancrenaz et al 2016) Based on spatial models, Struebig et al (2015) predicted many of orangutan habitat is no longer suitable in the future because of climate change. The number of bornean orangutan population is not precisely known.…”

Restoration planning of degraded tropical forests for biodiversity and ecosystem services

“…For our analysis, we used a habitat suitability map with strict treatment of possible omission errors (i.e. 25%), reflecting the core habitat inside the known geographical range of the species (Struebig et al, 2015a). We calculated habitat loss for each mammal by masking its habitat suitability map onto the oil-palm plantation map (Gaveau et al, in review).…”

“…As such, we assumed that restoration would fully recover the degraded areas to their pre-1950 condition. Historically suitable habitat was spatially modelled using the MaxEnt algorithm (Phillips and Dudík, 2008) and bioclimatic variables as predictors (Struebig et al, 2015b), and was then corrected with historical land cover (Struebig et al, 2015a). We employed a strict commission error threshold of 25% to assign habitat suitability of restored site into binary category.…”