2. Bettongs Join Forces with Truffles to Promote Tree Health

Bettongs Join Forces with Truffles to Promote Tree Health

Research by PhD Candidate: Susan Nuske (Research Grant 2014, 2015)

 

The northern bettong, Bettongia tropica (B.tropica), endemic to the Wet Tropics bioregion, is listed asendangered under the Nature Conservation Act 1992 (Qld)  and the Environmental Protection and Biodiversity Conservation Act 1999 (Cth). It is also ranked as critical priority in the “Back on Track species prioritisation framework” (Department of Environment and Heritage Protection). B.tropica has a diet made of up more than fifty-percent below-ground fungi (truffles) which are mostly ectomycorrhizal fungi. Ectomycorrhizal fungi associate in symbiosis with native trees such as Eucalyptus and sheoaks Allocasuarin spp. The fungi aid the vegetation in gaining access to nutrients and in resisting drought conditions.

Nuske’s project investigated the hypothesis “Is the endangered northern bettong, Bettongia tropica, a keystone ectomycorrhizal fungi disperser?” The project study area includes two sites within the Lamb Range, Davies Creek National Park and Danbulla State Forest.

The research objective was to determine:

1) the diversity and abundance of fungi that other mammals consume within the study areas

2) whether B.tropica has a fungal dispersal role above and beyond other mammals

3) whether the fungal community dispersed by mammals contributes a significant proportion of the functioningectomycorrhizal fungal community on tree roots.

Methods include collection and analysis of mammalian scats, truffles, mushrooms, tree roots and soil colonised byfungi.It was found that B.tropica is a significant and important disperser of truffle and ectomycorrhizal fungal species. Of the species it disperses, a significant portion were found not to be dispersed by any of the other nine generalist mammalian dispersers surveyed in the same habitat (see tables 1 and 2). Additionally, it was confirmed that B.tropica disperses three —of four— dominant fungal taxa which is associated with tree roots. These fungal communities facilitate plant health and nutrient cycling, promoting vegetation health.

From this research it can be understood that B.tropica is a keystone species, fulfilling a niche role within the ecosystem. As a fungal disperser B.tropica is essential to the life-cycle of many ectomycorrhizal truffle species and in maintaining tree-fungal relationships and ecosystem functions.

Specimens collected during this project will be stored at the Australian Tropical Herbarium and may inform further research projects into mychorrhizal fungal species of the Wet Tropics.

TABLE 1: Diversity of Fungal Species by Disperser
	TOTAL	Northern Bettong		Generalist Disperser
Ectomycorrhizal fungi	310*	254*	82%	159*	51%
Truffle fungi	150*	135*	90%	73*	49%
*Operational Taxonomic Units (molecular equivalent of species) of fungi found in disperser diets

TABLE 2: Unique Fungal Species by Disperser
	BOTH		Northern Bettong		Generalist Disperser
Ectomycorrhizal fungi	103*	33%	151*	49%	56*	18%
Truffle fungi	58*	39%	77*	51%	15*	10%
*Operational Taxonomic Units (molecular equivalent of species) of fungi found in disperser diets