Evidence of functional species sorting by rainfall and biotic interactions: A community monolith experimental approach

Abstract

1. Understanding the mechanisms that underlie species assembly is a central concern in community ecology. Abiotic and biotic filters are probabilistic 'sieves' that allow species with certain functional traits to become a part of the community, or not. We manipulated natural plant assemblies in order to identify variations in the timings of biotic and abiotic filters that determine community trait assemblies.2. We extracted soil portions when the investigated annual plant community was in its seed phase ('community monolith'), thereby maintaining the structure and similar soil characteristics to the field conditions. Community monoliths were subjected to experimental manipulation in terms of the rainfall timing and amount, and perturbations of the biological soil crust (BSC; intact vs. perturbed). We surveyed the experimental community assembly over time based on the functional diversity by considering important functional traits in different life stages.3. We found that autumn droughts acted as abiotic filters by favouring the germination and establishment of species with greater investment in the root biomass.Under severe droughts (66% water reduction), the experimental assemblies were dominated by species with functional traits adapted to water shortage conditions: high leaf dry matter content, low specific leaf area, small individual size, low reproductive ratio and high root:shoot ratio. We identified two roles of BSCs in annual plant species assemblies: (a) as a biotic filter that limited the establishment of species based on seed size, and (b) as a buffer against water stress conditions by reducing soil evapotranspiration. Synthesis.We demonstrated the importance of the timing and amount of rainfall for shaping annual plant communities, and identified germination filters as the main process that determined community assemblies. Our results suggest that the phenotypic integration of functional traits facilitates resistance to drought during the life cycle. The BSC-annual plant relationship shifted from negative, by acting as a germination filter, to positive, by acting as a buffer in later stages.Climatic fluctuations and fine scale biotic determinants of spatial heterogeneity emerged as sources of changes in the community assembly in time and space to

The role of root community attributes in predicting soil fungal and bacterial community patterns

“…This decoupling has been attributed to different causes, from low variation in plant richness in local‐scale studies (see Delgado‐Baquerizo et al ., 2018), to the blurring of the local effects of plant richness in global‐scale studies (Prober et al ., 2015). In our study, the decoupling between microbial and plant diversity may also be due to the existence of strong abiotic filters in our plant community (semiarid climate and gypsum soil) that may reduce trait variability among plant species (Escudero et al ., 2015; Pescador et al ., 2018; Peralta et al ., 2019), decreasing the range of variability of resources (Wardle et al ., 2004; Orwin et al ., 2010).…”

Precipitation Variability Affects Aboveground Biomass Directly and Indirectly via Plant Functional Traits in the Desert Steppe of Inner Mongolia, Northern China

“…Beyond that, researchers also confirmed that precipitation has experienced intense changes in intensity and variability since the last century (Alexander et al, 2006 ; Trugman et al, 2018 ; Paschalis et al, 2020 ). Water availability fluctuations induced by changes in precipitation modulate plant community dynamic and ecosystem function (Yang et al, 2011 ; Wu et al, 2016 ; Peralta et al, 2019 ). For example, changes in the distribution of rainfall events influence the patterns of species richness and species composition (Zavaleta et al, 2003 ; Báez et al, 2013 ; Cleland et al, 2013 ; Libalah et al, 2020 ), ecosystem net primary productivity (Fay et al, 2003 ; Heisler-White et al, 2009 ), and C cycling (Harper et al, 2005 ).…”

Demographic effects of interacting species: exploring stable coexistence under increased climatic variability in a semiarid shrub community

“…Agreement in population growth rates of H. squamatum and L. subulatum in certain years may be explained by the fact that survival and growth responded similarly to climate in both cases. Both species shared positive responses in years with dry springs (e.g., 2005 or 2012, see Supplementary Table S10), probably due to the fact that the diverse community of annual species that emerges in moist years is not able to develop under spring drier conditions [46][47][48] , thus reducing competition with our shrubby target species. Otherwise, contrasting population responses observed in certain years might be explained by their differences in the response of fecundity to spring rainfall: the late-flowering H. squamatum increased its fecundity in rainy springs, whereas L. subulatum showed the opposite pattern.…”