Communities structure and plant diversity in endangered canga (ironstone) vegetation: a reference ecosystem in the Brazilian semiarid region

Abstract

Compared with other hyperdiverse rocky ecosystems of eastern Brazil, canga vegetation, also known as campo rupestre ferruginoso, represents one of the least studied ecosystems but support a high proportion of rare and endemic plants. Large-scale iron mining is the primary cause of the loss and degradation of cangas. Therefore, there is a need to acquire knowledge about campo rupestre ferruginoso, both to support conservation planning and to provide information that can be used in ecological restoration models. In this study, we investigated the structure, diversity, and floristic composition of campo rupestre ferruginoso communities in four canga outcrops in a semiarid region and compared the values with those from existing studies on campo rupestre in eastern Brazil. A total of 5,724 individuals were sampled, and these individuals were distributed among 74 taxa, 54 genera, and 29 botanical families. We found that the plant communities in the cangas of the Vale do Rio Peixe Bravo are characterized by a unique set of functional groups, including a high proportion of succulents and poikilohydric plants, constituting an assemblage of specialized species. Considering the high degree of threat due to large-scale mining projects, our study revealed that the four cangas are in an excellent state of conservation, and we propose that they be considered reference ecosystems for future restoration projects.