Bryophytes on rocky outcrops in the caatinga biome: a conservationist perspective

Abstract

In the state of Paraíba, Brazil, there is an abundance of rocky outcrops, which are typical elements of the semi-arid landscape. Those outcrops provide refuge to species with morphological adaptations to stressful climates and to rare communities of plants, including bryophytes. Nevertheless, there have been no studies of bryophytes in such habitats in the state. Therefore, this work aimed to inventory bryophytes on two outcrops in the municipality of Puxinanã, in Paraíba, addressing some of the ecological aspects of survival in xerophytic environments. Samples were collected once every two weeks from February 2010 to May 2011. The usual techniques of bryophyte sampling and herbarium preservation were employed. We recorded 21 bryophyte species (six liverworts and 15 mosses), some of which are rare for Brazil. We performed cluster analysis, using the unweighted pair group method with arithmetic mean, based on the Sørensen similarity index. We thus defined three clusters among the studied outcrops and similar areas recorded in the literature. The rocky outcrops proved to be singular in terms of bryophyte species composition, which, as in most xerophytic environments, included light-demanding and generalist species, featuring various morphological adaptations to resist water stress, primarily in terms of their leaf structure. Our results demonstrate the urgent need for additional studies in the state of Paraíba, including floristic, conservation, evolutionary and biogeographic studies.

Keywords

• bryophyte
• inselberg
• morphological adaptations
• nonvascular flora
• semi-arid
• northeastern Brazil