Adjacent woodlands rather than habitat connectivity influence grassland plant, carabid and bird assemblages in farmland landscapes

Abstract

One response to biodiversity decline is the definition of ecological networks that extend beyond protected areas and promote connectivity in human-dominated landscapes. In farmland, landscape ecological research has focused more on wooded than open habitat networks. In our study, we assessed the influence of permanent grassland connectivity, described by grassland amount and spatial configuration, on grassland biodiversity. We selected permanent grasslands in livestock farming areas of northwestern France, which were sampled for plants, carabids and birds. At two spatial scales we tested the effects of amount and configuration of grasslands, wooded habitats and crops on richness and abundance of total assemblages and species ecological groups. Grassland connectivity had no significant effects on total richness or abundance of any taxonomic group, regardless of habitat affinity or dispersal ability. The amount of wooded habitat and length of wooded edges at the 200 m scale positively influenced forest and generalist animal groups as well as grassland plant species, in particular animal-dispersed species. However, for animal groups such as open habitat carabids or farmland bird specialists, the same wooded habitats negatively influenced richness and abundance at the 500 m scale. The scale and direction of biodiversity responses to landscape context were therefore similar among taxonomic groups, but opposite for habitat affinity groups. We conclude that while grassland connectivity is unlikely to contribute positively to biodiversity, increasing or maintaining wooded elements near grasslands would be a worthwhile conservation goal. However, the requirements of open farmland animal species groups must be considered, for which such action may be deleterious.

Multiscale drivers of carabid beetle (Coleoptera: Carabidae) assemblages in small European woodlands

“…Our results reveal that the composition of the landscape matrix into which forest patches are embedded significantly explains the α-and ated with a particular pool of species (Holland et al, 2005;Marrec et al, 2015), whilst grasslands may harbour less specific carabid assemblages and benefit from spillover from adjacent habitats, including forests (Duflot et al, 2018;Schneider et al, 2016). Moreover, arable lands may allow beetles to move more easily on the ground than grasslands, particularly because of differences in vegetation density (Thomas et al, 2006).…”

Contrasting multi-taxa functional diversity patterns along vegetation structure gradients of woody pastures

“…To account for potential effects of adjacent habitats on the studied biological communities we calculated proximate forest cover (cf. Duflot et al 2018) using interpretation of aerial photos within a 250 m buffer zone of the pastures (see Jakobsson and Lindborg (2015)). We used proximate forest cover instead of distance to the edge of the woody pastures because the contrast between woody pastures and the surrounding landscapes were typically not sharp in our study system.…”

Local and landscape responses of biodiversity in calcareous grasslands

“…These findings emphasize the hostility of landscapes that are dominated by intensive and homogenous cropland for species richness (Hallmann et al 2017;Kormann et al 2015). However, this effect was not pronounced for birds, which might be less sensitive to landscape connectivity and might be more tied to the presence of woody vegetation because of their higher mobility (Duflot et al 2018;Dorresteijn et al 2018).…”