Land‐use change alters the mechanisms assembling rainforest mammal communities in Borneo

Abstract

The assembly of species communities at local scales is thought to be driven by environmental filtering, species interactions and spatial processes such as dispersal limitation. Little is known about how the relative balance of these drivers of community assembly changes along environmental gradients, especially man-made environmental gradients associated with land-use change. Using concurrent camera- and live-trapping, we investigated the local-scale assembly of mammal communities along a gradient of land-use intensity (old-growth forest, logged forest and oil palm plantations) in Borneo. We hypothesised that increasing land-use intensity would lead to an increasing dominance of environmental control over spatial processes in community assembly. Additionally, we hypothesised that competitive interactions among species might reduce in concert with declines in α-diversity (previously documented) along the land-use gradient. To test our first hypothesis, we partitioned community variance into the fractions explained by environmental and spatial variables. To test our second hypothesis, we used probabilistic models of expected species co-occurrence patterns, in particular focussing on the prevalence of spatial avoidance between species. Spatial avoidance might indicate competition, but might also be due to divergent habitat preferences. We found patterns that are consistent with a shift in the fundamental mechanics governing local community assembly. In support of our first hypothesis, the importance of spatial processes (dispersal limitation and fine-scale patterns of home-ranging) appeared to decrease from low to high intensity land-uses, whilst environmental control increased in importance (in particular due to fine-scale habitat structure). Support for our second hypothesis was weak: whilst we found that the prevalence of spatial avoidance decreased along the land-use gradient, in particular between congeneric species pairs most likely to be in competition, few instances of spatial avoidance were detected in any land-use, and most were likely due to divergent habitat preferences. The widespread changes in land-use occurring in the tropics might be altering not just the biodiversity found in landscapes, but also the fundamental mechanics governing the local assembly of communities. A better understanding of these mechanics, for a range of taxa, could underpin more effective conservation and management of threatened tropical landscapes.

Assembly mechanisms of dung beetles in temperate forests and grazing pastures

“…Therefore, better knowledge on assembly mechanisms might be useful to develop appropriate restoration policies. For example, Wearn et al 4 suggest that if environmental filtering is the dominant driver of assembly, then steps to restore habitat quality may be important. Alternatively, if dispersal limitation dominates assembly, then restoring landscape connectivity might be more important.…”

“…Therefore, our ability to understand the relative importance of these not mutually exclusive assembly mechanisms is critical, as they can have high impacts on the conservation of local biodiversity and ecological functions. For example, a poor knowledge about the drivers of community assembly limit our capacity to predict the consequences of land-use change on diversity, and to devise useful management interventions in man-made landscapes 4 .…”

Scale‐dependent changes in tree diversity over more than a century in eastern Canada: Landscape diversification and regional homogenization

“…Disturbance has been hypothesized to weaken composition–environment relationships, for example by favouring a small pool of disturbance‐tolerant generalist species across the entire environmental gradient (Thompson, Carpenter, Cogbill, & Foster, 2013; Vellend et al., 2007). However, if disturbance regimes (type or intensity) are correlated with environmental gradients, disturbance might increase the strength of composition–environment relationships (Danneyrolles, Arseneault, & Bergeron, 2018; Hogan, Zimmerman, Uriarte, Turner, & Thompson, 2016; Wearn et al., 2018).…”

Tropical land-use change alters trait-based community assembly rules for dung beetles and birds

“…Understanding the dynamics of community assembly is critical for conservation strategies aiming to protect and restore tropical forests (Mayfield and Levine 2010;de Bello et al 2012;Fitzgerald et al 2017;Hung et al 2019). For example, communities driven by environmental filtering and competition (driven by limited resources) will potentially benefit more from conservation management focused on improving habitat quality and structure (Wearn et al 2018). Previous research has revealed significant impacts of tropical habitat modifications on community assembly of ants, understorey plants and small mammals in Malaysia (Fayle et al 2013;Döbert et al 2017;Wearn et al 2018), dung beetles in Brazil (Audino et al 2017), and trees in China (Ding et al 2012).…”