Functional Traits and Water Transport Strategies in Lowland Tropical Rainforest Trees: Deborah Apgaua

Whether plants can tolerate extended drought depends on how efficient and safe their water-conducting systems are. I studied the biological characteristics of rainforest plants in tropical rainforests at the Daintree, and found contrasting water-conducting strategies in different species. These results will help us predict plant vulnerability to drought.

Climate change scenarios predict extended droughts in tropical regions. Tropical rainforest plants may be negatively affected because they are adapted to regular water availability.

In my PhD, I study leaf and wood characteristics involved in water transport in 90 rainforest species that occur in the Daintree National Park. I examined the differences between different plant lifeforms (vines, shrubs and trees) and also between plants occurring in contrasting light exposure.

I found that leaf and wood features determine the volume and velocity of water that trees can transport in their stems. I also found that these characteristics vary among trees, and possibly reflects how those trees may respond to drought.

Comparing wood anatomical characteristics of trees with other groups of plants, I found a huge variation across these groups in the vessel sizes within their stem wood, reflecting distinct water-conducting strategies. Vines for example, have a mixture of very large and very small vessels, allowing them to achieve a highly efficient but safe water-conduction. Other like shrubs have uniformly small vessels and slow water transport, but possibly also a higher tolerance to drought.

This data will help us model how rainforests will change during climate change scenarios.

View the full results of Deborah's research project here or download a copy of the research paper here.


Fig. 1. PhD student Deborah Apgaua collects samples from the canopy crane at the Daintree Rainforest Observatory, Cape Tribulation

Fig. 2. View of lowland tropical rainforest from the Daintree Rainforest Observatory canopy crane

Fig. 3. Wood diversity of native rainforest trees at the Daintree Rainforest Observatory

Fig. 4. Wood anatomy of different plant lifeforms reflect their different water transport strategies