Abstract
AbstractWe aimed to determine the important functional dimensions that may drive forest succession and community assembly patterns in dry tropical forests. We investigated whether there were patterns in specific functional strategies during succession in the dry tropical forests of the Florida Keys, whose unique physical setting includes nutrient‐stressed, salt‐stressed, and water‐limited environments. The study, which focused on ten traits, determined the leading trait dimensions by which species differentiate from one another in the study area. The general patterns of trait covariation at individual sites and among species were analyzed using principal component analysis. Trait niche overlap indices were calculated for all species sampled across all plots. Evidence for/against likely community assembly processes was tested using the coefficient of heterogeneity to determine whether variation within and among five key traits was clustered, random, or evenly distributed across young, old, or all measured forest stands. A combination of plant architecture, wood density, and three leaf traits (specific leaf area, leaf phosphorus, and leaf nitrogen) comprised a key set of functional traits that are important for understanding the community assembly process in dry tropical forest. Older forest stands were dominated by species with low specific area, low leaf nitrogen content, dense wood, and deeper and narrower canopies. Trees of old forests had leaves with lighter carbon isotope composition, suggesting that such individuals were making more efficient use of scarce water. Tests of trait distributions showed significant clustering across forests of all ages. When individual trait distributions in old stands were tested, they displayed either randomly or evenly distributed traits across trait niche space, indicating that resource partitioning was predominant in shaping community composition. Physical traits of trees in young communities are associated with resource acquisitive strategies, while old communities are dominated by species with traits that enhance survival in environments defined by competition or chronic resource scarcity.
Highlights
Community assembly represents the outcome of differing strengths of competitive interactions and environmental filtering on a pool of candidate species present in an environment (Spasojevic and Suding 2012)
On the basis of the contribution of traits to the first three principal components, specific leaf area, wood density, leaf nitrogen, leaf phosphorus, multiple stem, and height to crown length (Ht):CL shape the most important trait niche axes among the species found along the successional gradient
Our investigation demonstrated that a combination of plant architecture (Ht:CL), wood density, and leaf traits comprises a key set of functional traits that are important for understanding succession and the community assembly process in dry tropical forest of the Florida Keys
Summary
Community assembly represents the outcome of differing strengths of competitive interactions and environmental filtering on a pool of candidate species present in an environment (Spasojevic and Suding 2012). Community assembly processes such as facilitation or plant–pollinator interactions can lead to trait similarity among species in a community (Cavender-Bares et al 2009, Kraft et al 2015). These ideas have led to a widespread expectation that trait variation among species is low in regions of strong abiotic stress and increases in regions where competitive interactions are stronger (Spasojevic and Suding 2012). Variation among multiple traits can be considered in the context of the functional niche concept where species are represented by an n-dimensional hyper-volume in functional space and trait niche axes are functions or processes associated with different functional attributes (Rosenfeld 2002)
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