Cross‐scale drivers of plant trait distributions in a fragmented forest landscape

Abstract

During community assembly, plant functional traits are under selective pressure from processes operating at multiple spatial scales. However, in fragmented landscapes, there is little understanding of the relative importance of local‐, patch‐ and landscape‐scale processes in shaping trait distributions. Here, we investigate cross‐scale influences of landscape change on traits that dictate plant life history strategies in re‐assembling plant communities in a fragmented landscape in eastern China. Using forest dynamics plots (FDPs) on 29 land‐bridge islands in which all woody plants have been georeferenced and identified to species, we characterized and derived two composite measures of trait variation, representing variation across the leaf economics spectrum and plant size. We then tested for trait shifts in response to local‐, patch‐ and landscape‐scale factors, and their potential cross‐scale interactions. We found substantial community‐wide trait changes along local‐scale gradients (i.e. forest edge to interior): more acquisitive leaf economic traits and larger sized species occurred at edges, with a significant increase in trait means and trait range. Moreover, there were significant cross‐scale interaction effects of patch and landscape variables on local‐scale edge effects. Altered spatial arrangement of habitat in the surrounding landscape (i.e. declining habitat amount and increasing patch density), as well as decreasing area at the patch level, exacerbated edge effects on traits distributions. We suggest that synergistic interactions of landscape‐ and patch‐scale processes, such as dispersal limitation, on local‐scale environmental filtering at edges, together shape the spatial distributions of plant life history strategies in fragmented plant communities.

Spatiotemporal patterns and ecological consequences of a fragmented landscape created by damming

“…However, few case studies have considered the fragmentation effects at multiple scales together under a hierarchical framework. In the TIL region, we found that plant traits were both affected by cross-scale interactions between the island and landscape features (Jin et al, 2020). Further, by observing interdependent effects at the plot-, island-and landscape-scales, we found that habitat fragmentation's effects were hierarchically structured (Wilson et al, 2020).…”

“…Besides ENN and distance to mainland, distance to the nearest larger island and island shape were also used as the proxies linking to the fragmentation per se at patch scale. Meanwhile, the patch number, patch density, and the relative habitat amount were used to measure the fragmentation degree at the landscape scale in previous studies in the TIL region (Hu et al, 2012;Jin et al, 2020;Wilson et al, 2020).…”

“…At the landscape scale, the species-area curve became steeper in the more fragmented landscapes, which was measured by habitat amount and patch number (Hu et al, 2012;Wilson et al, 2020). Studies also have also revealed that the effects of habitat fragmentation on biodiversity were scale-dependent, with hierarchical species-habitat linkages (Wilson et al, 2020) and cross-scale interactions affecting plant functional diversity (Jin et al, 2020).…”

Regional variability in landscape effects on forest bird communities

“…However, much idiosyncrasy remains among studies of functional responses to landscape pattern, whereby the relative importance of ecological processes seems to differ from place to place (Rhodes et al 2008;Morissette et al 2019), and findings from one study do not necessarily apply to others (Randin et al 2006;Lessard et al 2012). Such context-dependency is poorly understood (Shackelford et al 2016;Jin et al 2019), hampering the effective transferability of landscape-scale conservation and management policies (Gilroy et al 2014).…”

Tropical rainforest fragmentation affects plant species richness, composition and abundance depending on plant-size class and life history

“…In contrast, small-sized plants reflecting postfragmentation recruitment, should show stronger decline (Benítez-Malvido & Martínez-Ramos 2003). This pattern should be particularly the case of mature-forest, shade tolerant species, many of which are especially vulnerable to changes in abiotic factors (e.g., water stress, soil or air humidity or wind damage: Turner 1996, Scariot 1999, Benítez-Malvido & Martínez-Ramos 2003, Lasky et al 2013, Jin et al 2020 and biotic factors such as pollinators and dispersers (e.g., Cordeiro & Howe 2001, Osuri et al 2017. This latter expectation is consistent with documentation of the negative impact of fragmentation on animals that play such roles (e.g., Aguilar et al 2006, Cramer et al 2007, Moran & Catterall 2014.…”