Functional traits patterns along an altitudinal gradient in a large tropical forest region

Abstract

Understanding the link between functional traits and environmental gradients can provide important information to face global change. Here, we assessed how environmental variables act on functional trait-based ecological strategies of the acquisitive-conservative continuum and dispersal syndromes in forests of the Rio Doce Basin in Brazil's Atlantic Forest. Through literature and herbarium measurements, we gathered data on ten functional traits related to light interception, leaf economics spectrum, and reproductive ability from 1912 woody species across 79 localities. Relationships between community-weighted means of functional traits and an altitudinal gradient encompassing thermal and water availability variables were quantified using generalized linear models and principal component analysis. We found that in higher altitudes are predominant vegetative conservative functional strategies (smaller leaves and petioles) and reproductive acquisitive functional strategies (smaller fruits and seeds and abiotic dispersed species). The thermal variables mainly influenced vegetative functional traits, which showed a predominantly acquisitive strategy in warmer areas, where there are more favorable and stable conditions for rapid growth and resource uptake. The water variables had a pronounced impact on reproductive functional traits, particularly in terms of dispersal patterns. Water availability tends to impact the costs of fleshy fruits and seeds with higher energy content. The patterns found for the altitudinal gradient reflected a combination of thermal and water variables, which is congruent with the aggregative role of altitude, composed of multiple physical and climatic conditions. In conclusion, the abiotic factors are operating on a large landscape scale in the plant communities, exerting influence on functional traits along the altitudinal gradient in a tropical forest region.