From evergreen to deciduous tropical forests: how energy–water balance, temperature, and space influence the tree species composition in a high diversity region

Abstract

Background: Understanding floristic and geographic patterns in one of the most biodiverse regions in the world – the Atlantic forest of eastern Bahia, Brazil – can identify the drivers of diversity in tropical forests and provide useful information for biological conservation.

Aims: To understand the role of both climate and geographical location on variation in tree species composition in a region characterised by an abrupt transition from wet forests to semi-arid thorn-woodlands. To test whether a regional classification of forests according to elevation belts and leaf flush pattern is consistent with floristic composition.

Methods: We submitted 14,094 tree species occurrence records and 31 geo-climatic variables prepared for 57 sites in eastern Bahia, Brazil, to multivariate and regression analyses and variance partitioning.

Results: Climate and space were both significantly (P ≤ 0.05) contributing to explaining floristic variations. Actual evapotranspiration, duration of water deficit, and minimum temperature of coldest month were the main predictors. Floristic differences were significant except when comparing evergreen lower plains and upper plains forests.

Conclusions: Although distance among sites may play an important role, species composition is chiefly influenced by environmental gradients. This highlights environmental heterogeneity as a key factor in the planning of biodiversity conservation in tropical forests.

Keywords:

• Atlantic forest
• floristic gradient
• geo-climatic variables
• phytogeographic patterns
• spatial autocorrelation

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here.

Additional information

Funding

FZS thanks the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior for the Sandwich Fellowship [CAPES-7748/13-2]. ATOF [grant number 303458/2010-0] and MVRB ([grant number 311389/2013-9] and Post-doc Fellowship) thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). WWT and MRVB also thank the National Science Foundation [NSF-0946618].

Notes on contributors

Felipe Z. Saiter

Felipe Z. Saiter is professor of botany and biogeography. His research interests are forest ecology and phytogeographic patterns in the Brazilian coast.

Pedro V. Eisenlohr

Pedro V. Eisenlohr is professor of botany. He researches the patterns of species distribution and diversity in plant communities.

Maria R. V. Barbosa

Maria R. de Vasconcellos Barbosa is professor of botany and biogeography. Her research interests are taxonomy of Rubiaceae (Coffee family) and flora of northeastern Brazil.

William W. Thomas

William W. Thomas is a botany researcher. His research interests are taxonomy of Cyperaceae (Sedge family) and flora of northeastern Brazil.

Ary T. Oliveira-Filho

Ary T. de Oliveira-Filho is professor of vegetation ecology. His researches are focused on classification of the neotropical vegetation.