Within this section:
Introduction
Research
Conservation of
fauna and flora
The value of
remnant vegetation
Ecology of the
Red-capped Robin
Diversity of
invertebrates
Frogs as
bioindicators
Ecology and
behaviour of
frogs
Staff
Greg Gowing
Richard Major
Graham Pyke
Fieldwork Gallery
Diversity Gallery
Robin Gallery
Vegetation Gallery
Links

HomeResearch and CollectionsTerrestrial Ecology

Species diversity and genetic diversity of invertebrates in an agricultural woodland/landscape

Woodlands were once a continuous ecosystem covering much of central western NSW, but as a result of land clearance, only 10% of the native vegetation remains. As well as direct loss of habitat, fragmentation of the remaining woodland represents a major problem for maintenance of biodiversity. Much of the habitat which remains consists of small, isolated habitat islands supporting small populations of fauna. These small populations are vulnerable to local extinction due to low genetic variability and chance events, combined with reduced scope for dispersal and recolonisation.

In an attempt to mitigate the effects of habitat fragmentation several land-management agencies propose to create habitat networks in which fragments are linked by native vegetation. These proposals make use of existing corridors such as travelling stock routes and roadside reserves, but projects are also underway to plant trees to link remnants which are presently isolated. Revegetation programs serve a number of purposes: 1) to lower the water table, 2) to provide wind breaks thereby reducing soil erosion, and 3) to connect remnants to increase conservation value. As vast resources are expected to be expended on the program in the next decade, it is important to evaluate how well the programs meet their objectives.

Previous work on habitat fragmentation has focussed on vertebrates, with the implicit assumption that adequate conservation of vertebrates will ensure adequate conservation of invertebrates. However, if corridors are inadequate for vertebrates it does not follow that they will be inadequate for invertebrates - the group containing the vast majority of animal diversity.

We hope to answer the following questions with our research:

1. How are different species of invertebrate distributed across the different elements of the remnant ecosystem?
2. Do corridors have a role in maintaining species diversity?
3. Has fragmentation affected genetic variability of sub-populations?

We are sampling wolf spiders and plant bugs in each of six landscape elements: the interior of large state forests, the edge of large state forests, narrow roadside strips of vegetation, broad roadside strips of vegetation, small patches of vegetation and paddocks. We sample spiders by catching them in pitfall traps and by spotlighting them at night. We sample sap-sucking bugs by beating vegetation and collecting any which fall off into catching sheets.

Scanning electron micrograph of one of the sap-sucking bug commonly found on Callitris pine and belongs to the family Miridae. It's actual size is approximately 2.5mm.

In the laboratory, we examine the samples microscopically to sort the animals to species. This is done by looking for key character combinations which are unique to each species. We plan to check our species assignments by examining the genetic make-up of representatives of each of the species we identify.

This project has been funded by the State Government and work is being undertaken by Australian Museum staff Gerry Cassis, Fiona Christie, Don Colgan, Greg Gowing, Mike Gray and Richard Major. Invaluable volunteer assistance has also been given by Laura Collins, Tim Martin, John English, David Kingsland, Matthew Lindeyer, Barry Nielson, Helen Smith, Derek Smith, Sam Burns, Samantha Davis and the many landholders who have allowed us access to their land for research purposes.

Mirids mostly feed on plants and are therefore also likely to be adversely affected by loss of plants due to land clearance. Some Mirids have been known to cause damage to crops and many are ant mimics.

Top