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.

Dissecting a biodiversity hotspot: The importance of environmentally marginal habitats in the Atlantic Forest Domain of South America

“…Interestingly, this is consistent even within the subtropical section of the Atlantic Domain , where variation in community composition along the temperature seasonality gradient is congruent with increasing foliage deciduousness, a trait associated with frost-tolerance . A similar trend in species turnover and foliage deciduousness is also found in the tropical and equatorial sections of the Atlantic Domain, but the main driving force there is rainfall seasonality and the associated dry season Saiter et al, 2016).…”

“…Interestingly, this is consistent even within the subtropical section of the Atlantic Domain (Oliveira‐Filho et al., ), where variation in community composition along the temperature seasonality gradient is congruent with increasing foliage deciduousness, a trait associated with frost‐tolerance (Oliveira‐Filho et al., ). A similar trend in species turnover and foliage deciduousness is also found in the tropical and equatorial sections of the Atlantic Domain, but the main driving force there is rainfall seasonality and the associated dry season (Eisenlohr & Oliveira‐Filho, ; Saiter et al., ). Contrary to our expectations, temperature seasonality showed stronger explanatory power than the frequency of frosts, believed to be a chief factor limiting species distribution across temperature gradients (see Oliveira‐Filho et al., ; Rundel, Smith, & Meinzer, ; Scarano, ; Zanne et al., ).…”

Will seasonally dry tropical forests be sensitive or resistant to future changes in rainfall regimes?

“…Tropical forests are dynamic and have undergone directional shifts in composition and structure over decades to millennia (Phillips and Gentry 1994, Condit 1998, Laurance et al 2004, Chave et al 2008, Feeley et al 2011. In SDTF, species composition is strongly correlated to variables related to precipitation and temperature such as water storage capacity (Santos et al 2012), water deficit (Neves et al 2015), or evapotranspiration (Saiter et al 2015). Short-term changes in species composition and forest structure have important consequences for ecosystem response to global change.…”

Local environmental controls of Atlantic Forest tree community assembly on a coastal continental island in southeastern Brazil

“…spatial structure) to explain tropical tree community assembly at local-scale (< 20 km 2 ) heterogeneous terrain (Svenning et al 2004;Baldeck et al 2012;Cielo-Filho & Martins 2015). Most addressed this issue at large-scale (> 100 km 2 ) or by focusing on ferns and lycophytes instead of trees (Jones et al 2011;Bergamin et al 2012;Eisenlohr et al 2013;Rezende et al 2015;Saiter et al 2015;Arellano et al 2016;Nettesheim et al 2018). Studies of tropical tree community assembly at smaller local-scale are necessary to build comprehensive knowledge of niche-and neutral-related effects across different scales.…”

“…Brazilian Atlantic Forest remnants can yield important insights for this discussion because they are commonly located on mountain chains with highly heterogeneous terrain (SOS Mata Atlântica 2015). Studies showing the contribution of environmental conditions and spatial structure to explain plant community assembly in this forest have begun to appear recently (Bergamin et al 2012;Eisenlohr et al 2013;Cielo-Filho & Martins 2015;Oliveira-Filho et al 2015;Rezende et al 2015;Saiter et al 2015;Nettesheim et al 2018). Most of these studies indicate a greater role of niche-related environmental effects when compared to neutral-related spatial structure effects to explain vegetation changes.…”