The expansion of oil palm agriculture across Southeast Asia has resulted in substantial biodiversity declines across most taxa. However, palm oil is essential to global food security and provides incomes to millions of people, and therefore there is a need to reconcile trade-offs between biodiversity and economic interests. One way to reconcile trade-offs is to manage for biodiversity within existing plantations. Although considerably less biodiverse than forest, mature oil palm plantations (20 – 30 years old) can still support a wide range of generalist species, many of which provide essential ecosystem services and are therefore of great value to farmers and conservationists alike.
Biodiversity within mature oil palm plantations may be threatened by replanting. Replanting is part of the palm oil-production cycle that will soon occur across millions of hectares of plantation. Replanting changes vegetation complexity and microclimate, but impacts on biodiversity are little known. We surveyed an oil palm chronosequence (first-generation mature palms, and replanted second-generation palms aged one, three, and eight years) in industrial plantations in Riau, Indonesia to assess the impacts of replanting over an 8-year period on oil palm systems. We surveyed ground-, understory-, and canopy-inhabiting arthropods, which are abundant and functionally important within plantations.
Results/Conclusions
We identified 15540 arthropods from 24 orders across the studied microhabitats. Replanting caused no significant declines in total arthropod abundance in any microhabitat. However, order composition varied across the chronosequence in all microhabitats, due to changes in abundance of several arthropod groups. Furthermore, we found that the observed impacts of replanting depended on our level of taxonomic resolution. Focussed surveys of understory spiders indicated that replanting significantly reduced spider abundance and species richness, and substantially changed community composition, although these recovered to pre-replanting conditions within eight years of replanting. Our results highlight the resilience of arthropods to disturbance in tropical monocrops and suggest that replanting will have minimal long-term impacts on this functionally important group. Our findings also underscore the need for further research on the impacts of replanting of oil palm on other taxa, with implications for ecosystem services and crop yields.