TS-CRC Student project - Ecological patterns in vegetation and avifauna within fragmented tropical woodlands

James Cook University

Rosemary Allison

1998

Native vegetation continues to be cleared for agriculture, urbanisation and forestry in many regions of Australia, posing a serious threat to remaining native vegetation and fauna. The project's focus was to investigate patterns in vegetation and bird associations within fragmented tropical woodlands in coastal north Queensland. Variations in species composition were monitored during the dry and wet season on the Burdekin River floodplain and in the Bowling Green Bay National Park, north Queensland. The length of the project was 10 months: September 1997 to June 1998.

One of the objectives was to determine whether species composition and structural complexity of remnant vegetation deteriorated in fragmented landscapes over time and as patch sizes decreased. Vegetation surveys indicated that there was a considerable amount of variability in plant species composition throughout the study area. Structural complexity was the highest for communities within the National Park, which was attributed to the lengthy history of habitat disturbance on the floodplain. Also, it appeared that structurally similar woodlands supported a similar bird species composition, however, each contained a number of species that were unique to them.

Changes within the communities investigated clearly had a significant impact on their associated bird species. Within the patch sizes encountered the type of vegetation, rather than the size of remnant patches, determined species richness in woodland communities. Habitat disturbance on the floodplain benefited mainly large insectivorous and carnivorous birds, and as a consequence many of the bird species found within these areas are a reflection of their preference for open woodland communities. Surprisingly, there was no evidence of the expected reduction in species richness of particular guilds (groups of species that feed in the same way) in the disturbed sites.

The findings of this project highlight the importance of maintaining conservation areas outside National Parks. Regional conservation of species diversity can only be effectively achieved by the existence of both remnant patches of vegetation on the floodplain and relatively undisturbed communities within the National Park.  

Supervisors

A/Prof Richard Pearson, James Cook University
Dr Robert Congdon, James Cook University