Humidity, low temperature extremes, and space influence floristic variation across an insightful gradient in the Subtropical Atlantic Forest

Abstract

The use of well-sampled regions and insightful environmental gradients can provide important theoretical knowledge for understanding the drivers of tropical forest patterns and processes, which are necessary for biological conservation. We investigated the variation in tree species composition across a vegetation gradient in the Subtropical Atlantic Forest, as well as various predictors that could impact such patterns. The exploratory and confirmatory analyses included 178 sampling units distributed among 13 different forest types containing binary occurrence records for 935 species from 25,546 trees.Confirmatory analyses were conducted considering spatial autocorrelation, a well-known factor responsible for type I error inflations. The floristic heterogeneity of the study area was revealed by clear patterns of floristic differentiation between vegetation types, as well as by the significant improvements in local models (GWR-geographically weighted regressions) over global models (OLS-ordinary least squares). We found that the observed floristic variation has most likely been driven by humidity from the Atlantic Ocean, low temperature extremes and geographic distance. The latter was revealed by the high contribution of spatial components to the partial models. These results from a shrinking biological hotspot, particularly those concerning the importance of temperature extremes, represent crucial data for identifying conservation priorities, especially considering the seriousness of the temperature shifts predicted by global climate change scenarios.

Short gradient, but distinct plant strategies: The CSR scheme applied to subtropical forests

“…This is probably explained by the specific climatic conditions of this transitional region between climate types and biogeographic domains. Decreasing values of minimum temperatures, associated with extreme events, positively affected the contribution of component S, and increasing values of annual temperature range, associated with a broader variation in mean temperatures throughout the year, negatively affected the contribution of component C. Increasing values of both variables also positively affected component R. For subtropical southern Brazil, which presents high values of annual rainfall across the year, temperature is reported to be a more important variable in explaining species composition across forest types (Oliveira‐Filho et al., 2015; Rezende, Eisenlohr, Vibrans, & Oliveira‐Filho, 2015). For this region, decreasing mean annual temperature has been associated with tree species composition in both Pampean and Araucaria forests (Bergamin, Müller, & Mello, 2012; Oliveira‐Filho et al., 2015).…”

Variations in Leaf Morphological Traits of Quercus guyavifolia (Fagaceae) were Mainly Influenced by Water and Ultraviolet Irradiation at High Elevations on the Qinghai-Tibet Plateau, China

“…Abiotic conditions are the major factors that shape plant traits along elevational gradients (Hovenden and Brodribb, 2000;Körner, 2007;Thomas, 2011;Guerin et al, 2012;Rezende et al, 2015). Our results demonstrate that leaf area, shape factor, and petiole width are mainly influenced by MAP, whereas variations in leaf length, width, the ratio of leaf length to width, and petiole length are due to elevation-dependent fluctuations in both MAP and UV-B (Table 3).…”

“…Elevational clines represent a "natural laboratory" within which we can better understand how such traits fluctuate in response to growing conditions. This is because environmental factors change along an elevational gradient, even within a small geographical area in some cases (Hovenden and Brodribb, 2000;Thomas, 2011;Rezende et al, 2015). Moreover, when one considers their close associations with environmental factors, these morphological traits can be used to predict the consequences of climate changes (Hudson et al, 2011;Tsonev et al, 2014).…”

Efeitos De Um Ciclone Extratropical Na Biomassa De Árvores Em Fragmentos De Floresta Com Araucária

“…A Floresta Ombrófila Mista ou Floresta com Araucária faz parte do Bioma Mata Atlântica e recobre de forma contínua parte significativa dos estados do Sul do Brasil, além de áreas disjuntas no Sudeste, sempre em regiões de maior altitude e frias dos planaltos (DUARTE et al, 2014;KERSTEN et al, 2015;REZENDE et al, 2015). Nessas regiões, eventos climáticos de grandes proporções são incomuns, porém, tornaram-se mais frequentes nas últimas décadas (MARCELINO et al, 2009;LIMA & LOREDO-SOUZA, 2015), o que reforça a necessidade de estudos avaliando danos desses eventos sobre as comunidades florestais.…”

“…2) Como a dinâmica do recrutamento pode contribuir para biomassa após a passagem do ciclone? (REZENDE et al, 2015). A região encontra-se, geologicamente, na formação Serra Geral, que é constituída por rochas vulcânicas basálticas, onde predominam três tipos de solos: Cambissolo, Nitossolo e Latossolo.…”