Ecology and Conservation

Community ecology aims to understand the processes that separate a local community from a regional pool of species. These processes act as ecological filters that admit to a local community only those species that can persist under local conditions. These filters can be both abiotic (climate, soils etc) and biotic (predators, pathogens, competitors etc). The Group studies red land crabs, invasive yellow crazy ants and scale insects as biotic filters to the local assembly of rainforest seedling communities on Christmas Island (Indian Ocean). The rainforest ecosystem is notable for its high level of species endemism, recent species extinctions, and high-profile biological invasions. For more than three decades the Group has led research to understand the many species interactions which drive this ecosystem and the rise to dominance of yellow crazy ants. In collaboration with Christmas Island National Park we implement and monitor a major program of indirect biological control against the ant, targeting its key scale insect mutualist. We aim to mitigate invasive species threats and permit recovery of key species such as the Christmas Island Red Land Crab.

Communities consist of a few common species and many rare ones. One general idea is that rare species 'avoid' going locally extinct by performing better (higher rates of recruitment, lower rates of mortality etc) than more common species. To test this we study forest dynamics on the Connell Rainforest Plot Network, Queensland. We conduct long term demographic monitoring of rainforest trees to study diversity mechanisms in tropical and subtropical rainforests.

We tag and map all rainforest trees recording size (height or girth), free- standing stems of shrub and tree species. In 1963, Prof Joseph H. Connell (University of California) initiated these plots and sampling has been done ever since. We use molecular techniques to study the microbial root rhizosphere communities, their impacts on growth and potential to mediate plant species richness.

Species are filtered from the regional pool according to their key functional traits, and differences in filter number, type, and strength lead to variation in local community composition. Species sharing similar key functional traits share the same ecological 'strategy' and these reveal the selective forces that shape plant evolution. Grouping plants by their strategies provides a means of predicting vegetation responses to global change. We use the C-S-R Plant Strategy Scheme to assess long-term vegetation change in the Victorian Alps under climate change and the relaxation of cattle grazing.

These species have no or few close relatives, and are of special significance for phylogenetic diversity conservation. Our group works on the seabird Abbotts Booby and the grassland bird Plains Wanderer to study key habitat conservation management issues.