The effects of environmental constraints on plant community organization depend on which traits are measured

Abstract

Questions We test the hypothesis that soil water availability operates as an ecological filter on water economy plant traits, particularly in savanna stands, with consequences for species distribution and the functional profile of plant assemblages across a savanna–forest mosaic. Location A savanna–forest mosaic, northeastern Atlantic forest, Paraíba state, Brazil. Methods We sampled all trees and shrubs in 11 forest and 12 savanna plots in the same climatic region. Soil water storage capacity was measured, as well as the following traits: specific leaf area (SLA), internode mass fraction (IMF), maximum height (Hmax), wood density (WD), presence of trichomes (LT) and presence of abiotic seed dispersal (DD). Differences in trait values and water soil content between forest and savanna plots were assessed using Wilcoxon tests. Standardized effect size of functional richness and functional dispersion (SESFRic and SESFDis, respectively) were compared between forest and savanna plots with Wilcoxon tests, and the relationships between both functional indices of each trait and soil water content assessed using simple linear regression. We also used null models to test for habitat filtering in each plot, considering species assemblage (SESFRic) and abundance (SESFDis). Results Vegetation types differed in terms of soil water availability, with savanna soils having, on average, half the content of forest soils. Compared to forest, savanna plants had heavier internodes (30% increment), lower SLA (about 42% lower) and more plants with trichomes, but plants were much smaller across savanna assemblages. Savanna assemblages also exhibited a higher probability of trait convergence (i.e. reduced functional diversity) than forest assemblages in terms of SLA and maximum height, but savannas were less prone to trait convergence in terms of leaf trichomes, considering species abundance. Considering both vegetation types, a variable proportion of assemblages exhibited significant values of either FRic or FDis, but soil water availability did not correlate with functional diversity measures. Conclusions Habitat filtering not related to soil water availability favours the occurrence of conservative resource‐use plants across savanna stands, reinforcing the notion that filtering is able to act as an assembly force by affecting the abundance/frequency of particular traits, thus contributing to the occurrence of spatially organized mosaics of vegetation.

Current re-vegetation patterns and restoration issues in degraded geological phosphorus-rich mountain areas: A synthetic analysis of Central Yunnan, SW China

“…The first relates to plants and soils, while the second focuses on the need to address the social economy of mountain areas. First, regarding to the community self-organizing ability, there is involving species selection, community stability, and positive succession ( Sfair et al., 2016 ). Second, there is a need for the provision of market incentives for vegetation restoration.…”

Human‐mediated dispersal as a driver of vegetation dynamics: A conceptual synthesis

“…The plant traits selected by the post‐dispersal filters tend to be case‐specific, relating to the local environment (abiotic tolerances), interactions with the biotic community (e.g., competitive ability) and the relative importance of these two filters (Grime, 2006; HilleRisLambers et al , 2012; Sfair et al , 2016). We would expect dispersal ability — determined by traits such as dispersal mode, growth form, and seed size (Tamme et al , 2014), and also seed number (fecundity), which influences propagule pressure (Marteinsdottir and Eriksson, 2014) — to be a generic predictor of ability to pass through the dispersal filter.…”

Functional diversity of plant communities at edge and interior of a submontane Atlantic Forest: greater functional than compositional stability

“…The various modifications of the flora and fauna resulting from fragmentation can influence biotic interactions and affect ecological functions such as predation, parasitism, herbivory, pollination, seed dispersal and ecosystem services (Galetti et al 2003;Lopes et al 2009;McCauley et al 2013) as well as promote changes in the reproductive traits of plants (Girão et al 2007). Phenology, pollination and dispersal modes, especially abiotic syndromes, have been associated with plant strategies that coexist in seasonal contexts and affect ecosystem services (Jara-Gerrero et al 2011;Perez-Harguindeguy et al 2013;Sfair et al 2016). Researchers have reported significant differences in the reproductive phenologies of species as result of the formation of both natural and anthropogenic edges (Cunnigham 2000;Athayde & Morellato 2014;Pires et al 2014;Menezes et al 2018).…”