Environmental filtering is the main assembly rule of ground beetles in the forest and its edge but not in the adjacent grassland

Abstract

In a fragmented landscape, transitional zones between neighboring habitats are common, and our understanding of community organizational forces across such habitats is important. Edge studies are numerous, but the majority of them utilize information on species richness and abundance. Abundance and taxonomic diversity, however, provide little information on the functioning and phylogeny of the co-existing species. Combining the evaluation of their functional and phylogenetic relationships, we aimed to assess whether ground beetle assemblages are deterministically or stochastically structured along grassland-forest gradients. Our results showed different community assembly rules on opposite sides of the forest edge. In the grassland, co-occurring species were functionally and phylogenetically not different from the random null model, indicating a random assembly process. Contrary to this, at the forest edge and the interior, co-occurring species showed functional and phylogenetic clustering, thus environmental filtering was the likely process structuring carabid assemblages. Community assembly in the grassland was considerably affected by asymmetrical species flows (spillover) across the forest edge: more forest species penetrated into the grassland than open-habitat and generalist species entered into the forest. This asymmetrical species flow underlines the importance of the filter function of forest edges. As unfavorable, human-induced changes to the structure, composition and characteristics of forest edges may alter their filter function, edges have to be specifically considered during conservation management.

Assembly mechanisms of dung beetles in temperate forests and grazing pastures

“…Such a neutral dynamic assumes that, given random changes in their abundance, species have the same competitive capacity in both habitats, thus their coexistence depends on the ecological drift (an equilibrium between immigration and extinction processes 15 ). A similar pattern has been recently described for ground beetles in grasslands embedded within a forest matrix in the northern Hungarian mountains, where a random assembly structure is explained by the considerable asymmetrical species flow (spillover) from adjacent forests 19 . Although in our study area dung beetle species richness, abundance and diversity are higher in grasslands than in forest interior, 41% of the species have been caught in both habitats (Rios-Díaz et al, unpublished data).…”

“…An effective quantitative approach for understanding community assembly mechanisms is the use of functional trait-based diversity metrics 8,9,16,17 . For example, recent studies on ground-dwelling beetles have incorporated the analysis of functional traits to assess forest-grassland gradients 18 and community assembly rules 19 . Because they are related to species' niches, the variability of those traits within communities (i.e., functional diversity) is assumed to reflect the imprint of assembly mechanisms such as environmental filtering or competitive interactions.…”

Predation Pressure in Tea (Camellia sinensis) Plantations in Southeastern China Measured by the Sentinel Prey Method

“…There is also a potential seasonal variation [33] which we were unable to track. Spillover is also very likely influenced by the nature of edges [36]. Apparently, in our study system, the edges had a deterrent effect on arthropods active in forest fragments.…”

Various edge response of ground beetles in edges under natural versus anthropogenic influence: A meta-analysis using life-history traits

“…Therefore, forest edges can accumulate species from both adjoining habitats (Magura et al 2001, Harper et al 2005. Similar dispersal of ground beetles between forests and neighbouring open-habitat across edges is well documented (Lacasella et al 2015, Boetzl et al 2016, Magura 2017, Magura & Lövei 2018. They may have important roles in ecosystem services, like the pest control by predatory forest species in adjacent agricultural fields (Roume et al 2011).…”