Measuring community responses to large‐scale disturbance in conservation biogeography

Abstract

Aim Which community metrics should be used to reflect community response to large‐scale habitat alterations is unclear. Here, we assess what and how community changes should be measured to accurately track community responses to large‐scale disturbance in space and/or time. Location France. Method We first developed a simulation model to examine temporal changes in the species composition of large‐scale metacommunities. Using this model, we assessed how species richness, Shannon index, trends of particular subset of species or community indices of habitat specialization were influenced by different disturbance scenarios, and whether these indices were biased by imperfect detectability. We further used more than 1000 empirical bird communities from the French Breeding Bird Survey recently exposed to disturbances of various intensities as a case study. Results Our simulation and empirical results both demonstrate that species richness and diversity measures can show confusing trends and even provide misleading messages of communities’ fate. In contrast, reflecting the composition of the community in terms of habitat specialist and generalist species was more robust and powerful to reflect disturbance effects. Main conclusions We highlight the weakness of using community metrics that fail to incorporate ecological difference among species when summarizing community‐level trends in disturbed landscapes.

Patterns and causes of covariation in bird and butterfly community structure

“…Effects of habitat upon equivalent measures in birds were weaker, with widespread negative correlations between habitat-type and CSI indicative of the most specialised bird species being associated with rarer habitats, such as wetland. These results strongly suggest that butterfly communities in heavily anthropogenic habitats tend to be dominated by a relatively small number of evenly abundant generalist species, supporting previous results (e.g., Blair 1999;Dallimer et al 2012;Flick et al 2012), and the general principle that CSI decreases with land-use intensity (Devictor et al 2008;Devictor and Robert 2009;Filippi-Codaccioni et al 2010a, b). The negative correlation between habitat-diversity and avian CSI may result from squares with more heterogeneous habitat cover (indicative of fragmentation) being more likely to favour generalist, rather than specialist species (Dolman et al 2007).…”

Taxonomic and functional diversity of farmland bird communities across Europe: effects of biogeography and agricultural intensification

“…A series of recent studies have measured the response of farmland bird communities to habitat fragmentation and disturbance at the landscape level (Devictor and Jiguet 2007;Devictor et al 2008;Devictor and Robert 2009). However, the results presented here are, to our knowledge, the first to describe the effect of variables explicitly measuring agricultural intensification at the field and farm levels on farmland bird taxonomic and functional diversity at European scale.…”

“…Structural and functional changes in communities resulting from habitat degradation have been described in different types of ecosystems (Bradford et al 1998;Bryce et al 2002). More recently, several studies have assessed the response of farmland bird communities to habitat fragmentation and disturbance at the landscape level (Devictor and Jiguet 2007;Devictor et al 2008;Devictor and Robert 2009), showing how the use of indices based on the taxonomic and/or functional composition of assemblages can be applied to evaluate the ecological condition of communities and their habitats, which is a relevant issue in habitat management, ecological restoration and biodiversity conservation. Nevertheless, no previous study has evaluated the effect of agricultural intensification factors at the field and farm levels on farmland bird taxonomic and functional diversity at continental (i.e.…”

More and more generalists: two decades of changes in the European avifauna

“…Environmental change should therefore result in a non-random filtering of species within assemblages resulting in more similar communities. Measuring the relative occurrence [6] or abundance [4] of specialist species in local assemblages (the so-called community specialization index, CSI; [12]) can therefore reflect community response to large-scale disturbance [13] related to anthropogenic activities [4,14] and to climate change [15]. However, whether the cumulated responses of native species populations to environmental changes, measured at local (site) scales, can drive consistent trends in BH at national or continental scales remains unclear.…”