Satellite hindcasts of foliar traits reveal a subtle but consistent relaxation of conservativeness in a biodiverse mountain grassland over the last four decades

Projected warming and drying raise concerns about the resilience of stress-adapted ecosystems, including the Brazilian Campo Rupestre, an exceptionally biodiverse mountaintop grassland mosaic on ancient, nutrient-poor substrates. Here, we combine field-based trait data and long-term remote sensing to assess the functional structure and temporal dynamics of these communities.

Using foliar trait measurements from 247 vegetation plots across five contrasting habitats, we:

1) quantify contemporary community-level functional structure,

2) evaluate how edaphic and climatic filters shape spatial variation in community-weighted foliar traits,

3) reconstruct multi-decadal trait trajectories by hindcasting from long-term Landsat reflectance (1984–2022).

Contemporary communities occupy a narrow and predominantly conservative region of the leaf-economic trait spectrum, yet habitats differ in their functional positions within CSR strategy space, indicating non-uniform trait coordination despite overall conservatism. Soil texture and acidity define the primary conservative–acquisitive axis of trait variation, while climatic water balance acts as a secondary modulator; together, these predictors explain 39% of the spatial variation in community-weighted traits. Contrary to expectations of increasing conservatism under progressive climatic stress, Landsat-based hindcasts reveal only modest temporal reorganisation. Specific leaf area and leaf area increase across habitats, while leaf dry matter content declines slightly, indicating a subtle relaxation of conservative trait expression. Temporal changes are small relative to the pronounced spatial differentiation, suggesting strong functional inertia in this OCBIL system.

Overall, Campo Rupestre communities persist within a conservative functional domain while exhibiting fine-scale, habitat-dependent differentiation structured by enduring soil and water-balance gradients.