Rainforest conversion to plantations fundamentally alters energy fluxes and functions in canopy arthropod food webs

Tropical rainforests around the world are rapidly being converted into cash-crop agricultural systems. The associated massive losses of plant and animal species lead to changes in arthropod food webs and the energy fluxes therein. These changes are poorly understood, in particular in the extremely biodiverse canopies of tropical ecosystems. Using canopy fogging followed by stable isotope and energy flux analyses, we show that land-use conversion from rainforest to rubber and oil palm plantations not only causes a drastic reduction in energy fluxes of up to 75% but also shifts fluxes among trophic groups. While rainforests featured high levels of both herbivory and algae-microbiology, and a balanced ratio of herbivory to predation, relative fluxes were shifted towards predation in rubber and towards herbivory in oil palm plantations, indicating profound shifts in ecosystem functioning. Our results highlight that the ongoing loss of animal biodiversity and biomass in tropical canopies deg..., Study region and experimental design
Canopy arthropods were collected from research plots (n =32) of the EFForTS (Ecological and Socioeconomic Functions of Tropical Lowland Rainforest Transformation Systems) project in the lowlands of Jambi Province, Sumatra, Indonesia (Supplementary Fig. S1; Drescher et al. 2016), a region dominated by smallholder cash crop agriculture (Clough et al. 2016). Eight 50 m ⨯ 50 m plots each were established in three of the most dominant agricultural land-use systems in Jambi Province, i.e. monocultures of rubber (Hevea brasiliensis), oil palm (Elaeis guineensis), and jungle rubber (rubber agroforest system in gradually degrading rainforest remnants; Rembold et al. 2017), as well as in lowland rainforest as control habitat (Supplementary Fig. S2). The 32 research plots were located within and around two lowland rainforest reserves, i.e. the Bukit Duabelas National Park and the Harapan Rainforest, which are covered by degraded primary rainforest (Margono et a..., All statistical analyses were conducted with R version 4.1.0 (2021-05-18) \"Camp Pontanezen\".