Do riparian reserves support dung beetle biodiversity and ecosystem services in oil palm‐dominated tropical landscapes?

Abstract

Agricultural expansion and intensification are major threats to global biodiversity, ecological functions, and ecosystem services. The rapid expansion of oil palm in forested tropical landscapes is of particular concern given their high biodiversity. Identifying management approaches that maintain native species and associated ecological processes within oil palm plantations is therefore a priority. Riparian reserves are strips of forest retained alongside rivers in cultivated areas, primarily for their positive hydrological impact. However, they can also support a range of forest-dependent species or ecosystem services. We surveyed communities of dung beetles and measured dung removal activity in an oil palm-dominated landscape in Sabah, Malaysian Borneo. The species richness, diversity, and functional group richness of dung beetles in riparian reserves were significantly higher than in oil palm, but lower than in adjacent logged forests. The community composition of the riparian reserves was more similar to logged forest than oil palm. Despite the pronounced differences in biodiversity, we did not find significant differences in dung removal rates among land uses. We also found no evidence that riparian reserves enhance dung removal rates within surrounding oil palm. These results contrast previous studies showing positive relationships between dung beetle species richness and dung removal in tropical forests. We found weak but significant positive relationships between riparian reserve width and dung beetle diversity, and between reserve vegetation complexity and dung beetle abundance, suggesting that these features may increase the conservation value of riparian reserves. Synthesis and applications: The similarity between riparian reserves and logged forest demonstrates that retaining riparian reserves increases biodiversity within oil palm landscapes. However, the lack of correlation between dung beetle community characteristics and dung removal highlights the need for further research into spatial variation in biodiversity–ecosystem function relationships and how the results of such studies are affected by methodological choices.

Functional structure of ant and termite assemblages in old growth forest, logged forest and oil palm plantation in Malaysian Borneo

“…Also, a review of tropical forest dung beetle communities showed similar diversity declines with increasing habitat disturbance, along with a reduction in the number of forest species (Nichols et al 2007). A range of taxa including birds (Peh et al 2006;Koh and Wilcove 2008), butterflies (Koh and Wilcove 2008) and dung beetles (Edwards et al 2013;Gray et al 2014) show substantial losses of biodiversity when forest is converted to oil palm plantation (see also review by Fitzherbert et al 2008). Changes in assemblages, and particularly the loss of functionally important species, can have significant impacts on ecosystem functioning (Hooper et al 2005).…”

Threat of agricultural production on woody plant diversity in Tankwidi riparian buffer in the Sudanian Savanna of Ghana

“…However, certain outcomes of climate change can be mitigated by maintaining intact riparian landscapes-including retaining soil moisture, regulation of localized fire, and provision of refuge and dispersal corridors for fauna (Goetze et al, 2006;Azihou et al, 2013). Ecologically, riparian forests (RF) are important as they protect farmlands from flooding, drying and sedimentation (Gray et al, 2014). They provide shade and moderate stream temperatures for aquatic life.…”

“…Further, the forest cover reduces erosion and stabilises river banks (Surasinghe and Baldwin, 2015). Riparian forests also serve as habitat for fauna such as birds, insects and other organisms that are essential for crop pollination, seed dispersal and nutrient cycling (McCracken et al, 2012;Gray et al, 2014). Social benefits including oppor-tunities for tourism, medicines, nutrition, firewood, and raw material for different crafts and construction are derived from riparian forests (Ceperley et al, 2010).…”

“…Culturally, riparian forests are sometimes designated as sacred groove (Ceperley et al, 2010). Due to these functions and many others, some RF are protected by Ramsar convention, other national laws and policies (McCracken et al, 2012;Gray et al, 2014).…”

“…As a result, the riparian forests are under threat of deforestation which could change their microclimatic conditions to increase climate change effects on species and associated functions (Callo-Concha et al, 2012). In this savanna region, land areas dedicated to agricultural production are much greater than protected forest reserve areas (Traore et al, 2012;Gray et al, 2014). This means that the agricultural landscapes cannot be excluded from plant diversity conservation (Gray et al, 2014).…”