Characteristics and driving mechanisms of species beta diversity in desert plant communities

Abstract

Species dissimilarity (beta diversity) primarily reflects the spatio–temporal changes in the species composition of a plant community. The correlations between β diversity and environmental factors and spatial distance can be used to explain the magnitudes of environmental filtering and dispersal. However, little is known about the relative roles and importance of neutral and niche-related factors in the assemblage of plant communities with different life forms in deserts. We found that in desert ecosystems, the β diversity of herbaceous plants was the highest, followed by that of shrubs and trees. The changes in the β diversity of herbs and shrubs had stronger correlations with the environment, indicating that community aggregation was strongly affected by niche processes. The soil water content and salt content were the key environmental factors affecting species distributions of the herb and shrub layers, respectively. Spatial distance explained a larger amount of the variation in tree composition, indicating that dispersal limitation was the main factor affecting the construction of the tree layer community. The results suggest that different life forms may determine the association between organisms and the environment. These findings suggest that the spatial patterns of plant community species in the Ebinur Lake desert ecosystem are the result of the combined effects of environmental filtering and dispersal limitation.

The Diversity and Community Assembly Process of Wetland Plants from Lakeshores on the Qinghai-Tibetan Plateau

“…Also in plant communities, theoretically, the germination of alpine species in the QTP should be restricted to a certain period to avoid hostile environmental conditions to increase chances of successful establishment and reproductive growth [62], leading to weaker selection and higher stochastic colonization. Moreover, the environmental heterogeneity always reduces the efficacy of selection, hence, expanding the opportunities for co-occurrence of plants from different genera or families [57,63,64]. Although it is weak (r < 0.1), we observed a significant correlation between environmental similarity and geographic distance (Figure S4).…”

“…Quantifying stochasticity and determinism in governing community assembly is important but difficult [56]. Here, the community assembly process of the wetland plants on the QTP was clarified in three contexts: the null-model-based phylogenetic and taxonomic diversity metrics [56], the correlations between taxonomic/phylogenetic diversity and geospatial and environmental factors [46,57], and the components of geography and environment contributed to the similarity of community structure among sites [58]. Based on the performance of these three contexts, we inferred that stochastic and deterministic processes only played modest roles in the community structure of wetland plants.…”

Pervasive impacts of climate change on the woodiness and ecological generalism of dry forest plant assemblages

“…Aridification can also promote compositional change (Aguirre‐Gutiérrez et al, 2020; Ulrich et al, 2014) and reduce the beta diversity of dryland plant assemblages (Yan et al, 2020). As environmental filtering can better explain the beta diversity of herbs and shrubs than that of trees (Jiang et al, 2021; Murphy et al, 2016), woody species' distributions are likely at a lower equilibrium with climate than those of non‐woody species, implying that woody species may not keep pace with climate change. Projected changes in the species richness and beta diversity of Caatinga plant assemblages can therefore underestimate the impacts of climate change on plant assemblages with higher levels of woodiness.…”

Pervasive impacts of climate change on the woodiness and ecological generalism of dry forest plant assemblages

“…Aridification can also promote compositional change 28 and reduce the beta-diversity of dryland plant assemblages 29 . As environmental filtering can better explain the beta-diversity of herbs and shrubs than that of trees 30,31 , woody species' distributions are likely at a lower equilibrium with climate than those of non-woody species, implying that woody species may not keep pace with climate change. Projected changes in the species richness and beta-diversity of Caatinga plant assemblages can therefore underestimate the impacts of climate change on plant assemblages with higher levels of woodiness.…”