Help or hindrance? Untangling the role of Woody Liana Vines

A research team led by ARC Future Fellow, Associate Professor Andy Marshall from the University of the Sunshine Coast, is focussing on determining whether lianas—woody vines—help or hinder the recovery of forests after damage caused by tree-felling or cyclones, through the Forest Restoration and Climate Experiment (FoRCE).

Collaborating with the Wet Tropics Management Authority, various levels of government, local conservation groups, and private landowners, the researchers are gathering the data that underpins the daily forest management decisions about the finely balanced positive and negative impacts of these vines.

Dr Marshall says that lianas often grow extensively over the top of trees in disturbed tropical forests, slowing their growth and hence affecting the global carbon sink. But these lianas also protect forests from fire and cyclones, and if not properly managed, dried lianas can act as fuel for fires.

Increasing fire resulting from climate change is likely to worsen this effect because some forests will likely become too dry for lianas, leaving dried out vegetation behind for fires to spread—even up into the forest canopy. Such fire behaviour is unusual for rainforest areas, but Dr Marshall says that such fires have occurred recently in north Queensland, which is of great concern for forest managers.

Conducting the research involves gruelling, tropical field work. In Australia, the primary focus is the cyclone-impacted region around the Cassowary Coast and Atherton Tablelands, as well as areas from Lockhart River all the way down into areas of New South Wales where lianas grow. At the same time, the research team is mirroring the work in East Africa.

The research is helping to inform forest managers about how best to manage lianas that are smothering disturbed areas of forests—and answer questions such as whether liana vines should be cut away to free the trees, or left in place to protect trees from strong winds and fire.

By analysing the effects of lianas on forest recovery globally, the research is also revealing fundamental information about how forests work. In particular, the team will be searching for ‘thresholds’ of liana abundance that might be critical to forest recovery.

	“IF FORESTS HAVE FEW LIANAS THEN THEY HAVE LESS PROTECTION AND LESS DIVERSITY, WHICH MEANS THEY’RE LESS HEALTHY—BUT IF THEY HAVE TOO MANY LIANAS, THEN THESE FORESTS MAY NOT RECOVER. BOTH SCENARIOS WILL HAVE LASTING IMPACTS ON THE EARTH AND SO OUR RESEARCH IS WORKING TO GET ONE STEP AHEAD OF THAT,” DR MARSHALL SAYS.

 

Image: Research assistant Gerard Kyasapa cutting a vine thicket in Tanzania. Credit: Andrew R Marshall.