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Acta Botanica Brasilica

Print version ISSN 0102-3306On-line version ISSN 1677-941X

Abstract

SILVA, Joan Bruno; SFAIR, Julia Caram; SANTOS, Nivea Dias dos  and  PORTO, Kátia Cavalcanti. Bryophyte richness of soil islands on rocky outcrops is not driven by island size or habitat heterogeneity. Acta Bot. Bras. [online]. 2018, vol.32, n.2, pp.161-168.  Epub Jan 08, 2018. ISSN 0102-3306.  http://dx.doi.org/10.1590/0102-33062017abb0281.

The species-area relationship (SAR) is one of the oldest and most studied ecological models, having even served as the foundation of the Theory of Island Biogeography. Nevertheless, the relative importance of habitat heterogeneity to SAR remains poorly understood. Our aim was to test the relative importance of habitat heterogeneity to the SAR of bryophyte assemblages of soil islands of rocky outcrops in the semi-arid region of Brazil. We randomly selected 15 to 20 soil islands on each of four outcrops for a total of 59 soil islands, and calculated the area, mean depth, and number of substrates for each. We used Generalized Linear Models (GLM) to test the SAR with two models, one using species richness and another using life-form richness as the dependent variables. We found no positive relationship between area and habitat heterogeneity, nor any evidence of a SAR, such as a positive relationship between area and species or life-form richness neither between habitat heterogeneity and species richness. However, our findings did show that life-form richness is related to bryophyte species richness on the soil islands. We conclude by suggesting that not only can microclimate influence bryophyte richness, but opportunistic colonization by bryophytes is also important.

Keywords : Caatinga; inselbergs; Island Biogeography; microhabitat; species area relationship.

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