Environmental filtering of plant functional strategies in campo rupestre: implications for ecological restoration

Understanding how environmental filtering shapes plant functional strategies is essential for explaining community assembly and, ultimately, for guiding ecological restoration under global change. In highly stressful ecosystems such as the Brazilian campo rupestre, strong edaphic gradients and low ecosystem resilience make trait-based approaches particularly valuable for identifying reference conditions and restoration targets. Here, we investigate how plant functional traits and Competitor-Stress Tolerant- Ruderal (CSR) ecological strategies are filtered by soil properties across distinct campo rupestre habitats and explore the implications for restoration planning.

We quantified soil physicochemical properties, plant functional traits, and CSR strategies for 111 species across 120 plots representing four distinct campo rupestre habitats (rocky outcrops, stony grasslands, sandy grasslands, and peatbogs) in the Espinhaço Mountain Range, Brazil. Trait-environment relationships were evaluated using fourth-corner and RLQ analyses to assess both bivariate and multivariate associations between species traits, ecological strategies, and edaphic gradients.

Plant community assembly was strongly structured along a primary gradient of resource and water availability. Ruderal strategies were associated with higher nutrient concentrations and greater soil water-holding capacity, whereas stress-tolerant strategies were favored in coarse-textured, nutrient-poor soils. Individual traits mirrored these patterns: higher leaf mass per area and wood density were associated with resource-poor environments, whereas greater plant height was associated with increased nutrient availability. These results indicate strong coupling between plant functional strategies and soil conditions, with limited functional redundancy under extreme environments.

Our findings demonstrate that edaphic filtering is a key driver of functional differentiation in campo rupestre plant communities. By linking soil conditions to functional strategies and traits, this study provides a mechanistic framework for defining habitat-specific functional targets, offering a robust basis for conservation and ecological restoration in this highly vulnerable ecosystem.