Cross-boundary subsidy cascades from oil palm degrade distant tropical forests

• Main Authors: Luskin, Matthew Scott, Brashares, Justin S., Ickes, Kalan, Sun, I-Fang, Fletcher, Christine, Wright, S. Joseph, Potts, Matthew D.
• Other Authors: Asian School of the Environment
• Format: Article
• Language: English
• Published: 2019
• Subjects: DRNTU::Science::Geology; Tropical Forests; Wild Boars
• Online Access: https://hdl.handle.net/10356/81286; http://hdl.handle.net/10220/47460
• Institution: Nanyang Technological University

Native species that forage in farmland may increase their local abundances thereby affecting adjacent ecosystems within their landscape. We used two decades of ecological data from a protected primary rainforest in Malaysia to illutrate how subsidies from neighboring oil palm plantations triggered powerful secondary ‘cascading’ effects on natural habitats located >1.3 km away. We found (i) oil palm fruit drove 100-fold increases in crop-raiding native wild boar (Sus scrofa), (ii) wild boar used thousands of understory plants to construct birthing nests in the pristine forest interior, and (iii) nest building caused a 62% decline in forest tree sapling density over the 24-year study period. The long-term, landscape-scale indirect effects from agriculture suggest its full ecological footprint may be larger in extent than is currently recognized. Cross-boundary subsidy cascades may be widespread in both terrestrial and marine ecosystems and present significant conservation challenges.