Global patterns in the functional traits of native and invasive vines

Background/Question/Methods

Functional traits describe how species ‘make a living’ in the constraints of their physical environment using physiological, morphological and phenological adaptations. As a result, traits are being used increasingly to replace taxonomic identity as a means to understanding diversity and dynamics of vegetation worldwide and have rapidly become the new empirical currency of plant ecology. However, climbing plants are notoriously underrepresented in many large-scale compilations of plant trait data, despite being important drivers of vegetation change, particularly where they become invasive. To address this knowledge gap in climbing plant ecology a comprehensive global dataset of traits was compiled and used to test hypotheses about how functional attributes vary with latitude and climate, and among major biogeographical regions of the world.
Data on seed mass, leaf size, specific leaf area, climbing mechanism, dispersal mode, and growth habit were compiled for 1092 species found in 34 countries. For each trait I: (1) quantified the strength of latitudinal and climatic gradients using analyses across species and across evolutionary divergences, (2) tested for phylogenetic signal in traits (the tendency for closely related species to exhibit similar traits), and (3) compared trait variation and phylogenetic clustering between four major biogeographical regions of the world (Africa, the Americas, Asia, Australasia). These hypotheses are explored across all 1092 species and in a subset of known invaders.

Results/Conclusions

Highly significant relationships between latitude and four traits (growth habit, leaf size, seed mass and specific leaf area, SLA) were found. Leaf size, seed mass, and SLA also showed significant relationships to mean annual temperature and precipitation. However, no relationship was found between dispersal mode and latitude or climbing mechanism and latitude. These results were largely consistent in cross-species and phylogenetic analyses. All traits, except seed mass, exhibited clear differences between biogeographic regions. SLA and seed mass were the only two traits that did not present a significant phylogenetic signal. Phylogenetic clustering was detected in species from the Americas and Africa, indicating that trait conservatism is important in broad biogeographical regions.
Understanding variation in function among climbing plant species is an important tool for better invasive plant management. Being able to target species with acquisitive growth strategies (e.g. high SLA) or high seed output (e.g. small seed mass) early in the invasion process may increase the efficiency of eradication efforts ultimately reducing the impact on native vegetation.