Biodiversity maintenance in human-modified landscapes largely depends on spatial variations in species composition (β-diversity), but the impact of human disturbance on β-diversity remains poorly understood. We examined how taxonomic and phylogenetic β-diversity of woody plant communities in the Brazilian Caatinga dry forest respond to two emerging threats—chronic anthropogenic disturbance and water scarcity. We separately assessed diversity metrics that give a disproportionate weight to rare species, and metrics weighted by dominant species. We recorded a total of 5118 individuals from 104 species across 19 0.1-ha plots into a 21,430-ha human-modified landscape exposed to chronic disturbances and a high variation in climatic water deficit. At the landscape scale, β-diversity was higher when considering rare species than when focusing on dominant species, especially for the phylogenetic dimension of β-diversity. Water deficit was the primary driver of plant taxonomic and phylogenetic β-diversity, followed by the number of cattle and inter-site isolation; however, rare species seem to depend more strongly on these factors than the dominant ones. Therefore, preserving as much forest as possible, including areas exposed to different disturbance level and climate variables, is critical to prevent the loss of rare species and maintain the compositional differentiation of biotic assemblages. Such forest cover should be maintained in a large number of forest patches scattered through the landscape to preserve biologically and functionally distinct components of this ecosystem, avoid landscape-scale biotic homogenization, and thus favor its ecological resilience.
Bibliographical noteFunding Information:
This study was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (PELD process 403770/2012-2, Universal process 470480/2013-0), Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (APQ process 0738-2.05/12, PRONEX 0138-2.05/14). K.F.R. thanks FACEPE for her PhD scholarship (FACEPE process IBPG-0452-2.03/11). I.R.L. and M.T. thank CNPq for productivity grants. Most analyses were done while K.F.R. was on a research stay at the Instituto de Investigaciones en Ecosistemas y Sustentabilidad (IIES), UNAM, Morelia, Mexico funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes process PDSE-99999.008145/2014-08), and most writing was done during the postdoctoral stay of K.F.R. at IIES, funded by the Dirección General de Asuntos del Personal Académico (DGAPA-UNAM). M. T. research in the Caatinga dry forest was supported by the Alexander von Humboldt Foundation.
© 2021, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature.
- Chronic human disturbances
- Climatic change
- Dispersal limitation
- Species turnover