Botanic Gardens Trust, Sydney, Australia

Australian rainforest through time - functional and phylogenetic structure

Dr Robert Kooyman - Honorary Research Associate, Dr Maurizio Rossetto - Principal Research Scientist and Manager Evolutionary Ecology

Research overview

The evolutionary history of plant species and the environments they live in shape their form, function, and abundance. As climate changed species adapted, shifted in abundance, survived in the conditions they evolved in, or went extinct.

At continental scales and through time, the transition of Australia from a rainforest dominated continent to the driest habitable continent on earth remains of fundamental scientific interest. This research is focused on quantifying the variation in (plant) functional traits across environmental gradients and the evolutionary structure of plant communities across the whole continent. These measures can provide insights into the climatic, geological and topographic factors that shape rainforest community assembly and influence plant interactions (Kooyman et al. 2011).

Community ecology is the investigation of the nature of interactions among organisms. It includes both the origins of those interactions, and their ecological and evolutionary consequences. We have quantified trait values for seed size, fruit size, fruit colour, dispersal mode, leaf area, flower size, flower colour and maximum height at maturity for all of Australia’s woody rain forest species (c. 2400 taxa) across the continental range of their distributions and environmental variation (e.g. Kooyman et al. 2012a,b).

Summary of community assembly results

Stable moist forest areas retain many species from ancestral (Gondwanan) rainforest lineages. Within temporally conserved moist forest habitats species in assemblages were found to be less related. These rain forest assemblages were comprised of species that collectively had higher functional (trait) diversity, but lower niche breadth (i.e. more constrained distributions). Results for historically more disturbed areas show that rainforest contraction and re-expansion can result in recolonized areas that are dominated by species that are more related (phylogenetically) than by chance, have smaller, widely dispersed seeds, and greater niche breadth (broader distributions) (Kooyman et al. 2012a).

In relation to achieving conservation biology objectives, we believe being able to predict which sort of plant species will do what is critical for managing Australia’s native vegetation into the future.

 

 

 

 

Robert Kooyman
R. Kooyman investigating a large fig collapsed after a storm in Northern NSW. Photo: M. Rossetto