Do riparian reserves maintain biodiversity and ecosystem functioning in oil palm dominated landscapes?
Oil palm is central to Malaysia’s economy and welfare of rural society, but has known environmental impacts on water quality, ecosystem functions and biodiversity if not managed sustainably. To help minimise hydrological problems Malaysia, like other tropical countries, requires companies to protect vegetation (20-30m) along rivers in oil palm plantations. Amidst growing interest in sustainability, the perceived benefits of this policy have also extended to provisions for endangered biodiversity and crucial ecosystem services such as reduced agricultural runoff and eutrophication. Riparian reserves could even be important to help mitigate against climate change by storing carbon in tree biomass and serving as critical wildlife corridors, aiding animal movements across human-managed landscapes to forest habitats that remain ‘climate-safe’.
Surprisingly, unlike in temperate regions, there is very little scientific evidence supporting any of these benefits in the tropics. There is little information available about how the size of riparian buffer zones influences their ecological and biogeochemical functioning, and we have a poor understanding of how catchment size or the intensity of disturbance in the surrounding landscape matrix influences riparian zone function. It remains to be seen whether there is a threshold of disturbance size or intensity above which riparian zones cease to be effective. Additional data are needed to perform an integrated assessment of riparian buffers to evaluate their effectiveness for biodiversity conservation and maintenance of ecosystem functioning, and to determine if the Roundtable on Sustainable Palm Oil (RSPO) and national statutory requirements are sufficient to meet their environmental objectives.
LOMBOK scientists are now addressing this issue thanks to additional funding from NERC, the British Council and the Malaysian Industry-Government Group for High Technology (MIGHT) via the Newton-Ungku Omar Fund. We have established a network of biodiversity monitoring and carbon (C) dynamics plots within riparian areas at SAFE, and preliminary work indicates that riparian strips are important for some biodiversity components. To determine the effectiveness of riparian policy we are investigating the influences of riparian habitat quality/width on water quality, aquatic and terrestrial biodiversity, and carbon stocks and emissions around oil palm plantation rivers and appropriate control sites. We are also extending our work on food web dynamics and exploring the potential for riparian habitats of varying sizes to serve as dispersal corridors linking forest patches.