Biotic filtering and mass effects in small shrub patches: is arthropod community structure predictable based on the quality of the vegetation?

Abstract

1. Community assembly is affected by four processes: dispersal, filtering effects (selection), ecological drift and evolution. The role of filtering relative to dispersal and drift should decline with patch size, hampering possibilities to predict which organisms will be observed within small‐sized patches. However, vegetation structure is known to have a marked impact on species assemblages, and plant quality may act as a biotic filter. This challenges the assumption of unpredictable species assemblages in small‐sized vegetation patches.2. Using 32 stands of five shrub species in south‐west Finland, this study investigated whether biotic filtering effects caused by patch‐forming plants are strong enough to overcome the mixing of mobile arthropod assemblages across small patches.3. Stochastic variation did not hide the signals of biotic filtering and dispersal in the small shrub patches. Habitat richness around the patches explained a three times larger share of variation in the species composition than did the identity of the patch‐forming plant, but it had less effect on the abundance of arthropods. A radius of 50–100 m around a patch explained the species composition best.4. Abundance patterns varied between the feeding guilds; the patch‐forming shrub influenced the abundances of detritivores and leaf‐feeding herbivores, whereas the abundances of flower‐visiting herbivores appeared to track the flowering phenology of the plants. Shrub identity had little effect on omnivores or predators. Predator abundances were correlated with the abundance of potential prey.5. The results of this study suggest that community composition within a vegetation patch may be predictable even if dispersal overrides local filtering effects, as suggested by the mass‐effects paradigm.

Shrub and precipitation interactions shape functional diversity of nematode communities on the Qinghai–Tibet Plateau

“…We found shrubs decreased the functional richness difference component, which suggested that the functional homogenization is often linked to deterministic processes of environmental filtering (Si et al, 2016; Zhao et al, 2021). Shrubs functioning as habitats for nematode communities can limit the range of potential colonizers by favoring species with particular functional attributes (Cao et al, 2016; Lanta et al, 2018). Combined with the single functional traits and functional composition, shrubs increased body mass, C – P value, and proportions of omnivore and predator nematodes.…”

“…Shrubs and its interactions with precipitation can potentially influence the processes behind community assembly, and therefore functional beta diversity. On the one hand, functioning as habitat for nematodes, shrubs can limit the range of potential colonizers by favoring or excluding species with particular functional attributes, decreasing nematode functional beta diversity (Lanta et al, 2018; Siegwart Collier & Mallik, 2010; Wardhaugh et al, 2012; Xiang et al, 2019). Moreover, shrubs trigger large shifts in soil heterogeneity that limit local species coexistence, decreasing functional richness differences and overall functional beta diversity of nematode communities (Albrecht et al, 2021; Chesson, 2000; Hao et al, 2021; Losapio et al, 2018; Schöb et al, 2013; Trentanovi et al, 2013).…”

Strong homogenization effects of shrubs on nematode communities across large spatial scales on the Qinghai-Tibet Plateau

“…Shrub encroachment is an irreversible process with potential effects on the soil environmental heterogeneity and plant communities, thus affecting the beta diversity of soil communities (Hao et al , 2021). On the one hand, shrubs, which function as habitat for soil communities, could limit the range of potential colonizers by favoring or excluding species with particular functional attributes, which would directly decrease beta diversity of soil communities (Siegwart Collier & Mallik, 2010;Wardhaugh et al , 2012;Lanta et al , 2018;Xiang et al , 2019). On the other hand, shrub triggers large shifts in plant communities and soil environmental heterogeneity, indirectly affecting beta diversity of soil communities.…”

Environmental filtering and spillover explain multi-species edge responses across agricultural boundaries in a biosphere reserve

“…mass effects or spillover) 29 , 30 . In this case, high dispersal rates maintain species in sites with negative growth rates 31 and override the effects of local selection 8 , 18 , 30 , 32 .…”