Geographic space, relief, and soils predict plant community patterns of Asteraceae in rupestrian grasslands, Brazil

We investigated the effects of geographic distance and environmental heterogeneity on Asteraceae communities in the rupestrian grasslands of the Espinhaco Range, southeastern Brazil. Asteraceae species composition and relative abundance were sampled in 21-1 ha plots distributed across park conservation units, comprising an environmental gradient in soils and relief (elevation and slope). We found high levels of heterogeneity overall in assemblages of herbaceous and woody Asteraceae species at the intermediate spatial scale of this study (10-100 km). We found that both relief and soil properties (texture and total exchangeable bases) explained significant proportions of variation in community composition, suggesting that definitions or expansions of conservation units should span the highest possible variability in observed relief and soil values. We also found that Asteraceae distribution exhibited strong spatial structure independent of environmental variation, reinforcing the need to consider conservation across larger areas. Considering the dystrophic character of the soils found in the Espinhaco Range and the few differences in the fertility observed between the sampling units, our results also support the hypothesis that plant distributions in the tropics are controlled by a hierarchy of environmental gradients, where variables such as altitude and exchangeable bases and Al texture are important predictors in low-fertility soils. We suggest that Asteraceae could be a model family for conservation planning in other countries and regions because it is particularly well represented in open and montane areas of the Neotropics in general. in Portuguese is available with online material.