PS 69-80 - Using trait variation to understand plant distribution across an elevational gradient in a neotropical savanna

Friday, August 11, 2017
Exhibit Hall, Oregon Convention Center
Annia S. Streher, Instituto de Biociências, Universidade Estadual Paulista (Unesp), Rio Claro, Brazil, Brian J. McGill, School of Biology and Ecology / Mitchell Center for Sustainability Solutions/Mitchell Center for Sustainability Solutions, University of Maine, Orono, ME, Patricia Morellato, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rio Claro, Brazil and Thiago Sanna Freire Silva, Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista (Unesp), Rio Claro, Brazil

Known for its megadiverse vegetation, the Serra do Cipó region in Brazil comprises a tropical elevation gradient, where high floristic richness is favored by the influence of three adjacent biomes (Cerrado, Atlantic Forest, and Caatinga), and locally by high soil diversity, habitat heterogeneity and microclimatic variation. To unravel the mechanisms underlying plant species distribution at Serra do Cipó, we evaluated (i) what are the trade-offs between acquisitive versus conservative resource-use traits and its relationships with the environmental gradients; and (ii) how do leaf traits and vegetation height vary within and among elevations? Five sampling locations, arrayed along the elevational gradient (600 to 1420 m) were sampled using four transects each, during the 2016/2017 growing season. At each transect, individuals encompassing different life forms were sorted by morphospecies and measured for plant height at maturity and triplicate mature sun leaves were harvested for leaf dry matter content (LDMC).


In total, we sampled 1650 individual plants and 4950 leaves, representing the majority of plant phenotypes found at Serra do Cipó. Initial results show two main patterns of trait variance. First, traits had contrasting responses to elevation: plant height was negatively correlated with elevation, with average values ranging between 230 cm (± 153 s.d.) at the lowest site and 59 cm (± 49) at the highest site, while average values of LDMC had the opposite behavior, with smaller variations, ranging from 0.37 (± 0.08) to 0.39 (± 0.1) g g-1. The large variance within sites is consistent with a plastic response to small-scale environmental gradients. Moreover, LDMC values indicate a conservative resource-use strategy, with plants favoring slow growth rates and long leaf lifespans, common of nutrient-limited soils and often-disturbed sites, like the fire-prone vegetation at Serra do Cipó. Our preliminary results highlight how local factors may strongly affect the functional structure of plant communities in tropical mountains, perhaps dominating over large-scale environmental drivers (e. g. air temperature and precipitation). Further analyses will focus on the relationship between different life forms, other traits and optical properties that were also measured, and specific aspects of the environmental gradients (soils and microclimates), to better understand the processes driving assembly patterns in a megadiverse tropical elevational gradient.