The impacts of tropical cyclones on rain forest structure and functioning

Tropical cyclones are frequent events that can cause severe damage to ecosystems and infrastructure on large scales. Global warming as a result of the enhanced greenhouse effect is causing cyclones to become more intense and to occur at higher latitudes. Surprisingly, we know little about the long-term impacts that cyclones have on the structure and functioning of ecosystems and what to expect as climate change progresses.

This project will investigate the impacts of cyclones on ecosystems, using tropical rainforest as a model system. It brings together experts from throughout Oceania, including Gunnar Keppel (University of South Australia), Thomas Ibanez (University of Hawaii), Peter Vesk (University of Melbourne), John Dwyer (University of Queensland), Christophe Menkes (IRD, Nouméa), Dan Metcalfe (CSIRO) and Ted Webb (National University of Singapore). The project aims to address three key questions:

1. What are the short-term and long-term impacts of cyclones on rainforests
2. What are the effects of cyclones on the structure and functional traits of rainforests?
3. What are the likely impacts of changes in cyclone activity under anthropogenic climate change on the carbon stocks, structure and functioning of forests?

Firstly, and using past cyclone data, we will reconstruct current cyclone activity in tropical and subtropical regions and use trends in the data and models of future climates to impute future cyclone activity. Secondly, and using measurements of the dimensions and functional traits of trees, we will quantify the current structure and functioning of rainforests along gradients of cyclone activity in Australia and on South Pacific Islands. Finally, combining the cyclone and forest data, we will use trends in tree dimensions and functional traits along the gradient to forecast the structure and functioning of rainforests under forecasted future cyclone activity.

Results will allow forecasting impacts of changes in cyclone activity on forest ecosystems. Predictions for tree dimensions and plat functional traits can be combined to forecast how changing cyclone activity will alter the capacity of forests to store carbon. We will also be able to identify characteristic (functional traits) of trees that determine whether a tree species will be negatively or positively impacted by changes in cyclone activity. This information about carbon storage and species responses will be important for the management of carbon stocks and the conservation of rainforest species, respectively. Therefore, our data will improve conservation practices by allowing more informed conservation actions for tree species and cyclone-adapted forest management.