Wetland Science
Local and regional macroinvertebrate diversity in the wetlands of a cleared agricultural landscape in south-western Victoria, Australia
Belinda J Robson and Colin J Clay, School of Ecology and Environment, Deakin University. Aquatic Conservation: Marine and Freshwater Ecosystems. 15: 403-414 (2005).
Summarised by Laura Torrible, WetlandCare Australia
Introduction
Although this study is regionally specific, the information is interesting for all wetland managers. The study showed that the biodiversity of aquatic insects in the wetlands found in an agricultural landscape in South-western Victoria were similar to the aquatic insect populations found in wetlands elsewhere, despite being used for grazing purposes.
This information suggests that wetlands on grazing properties may have conservation value and should be managed to protect them from threatening processes such as drainage.
A full copy of the report is available through the scientific publication; Aquatic Conservation: Marine and Freshwater Ecosystems.
Seasonal wetlands
Seasonal wetlands are present only during the wet season (winter-spring in southern Australia). The depth, duration and extent of winter rainfall will vary and affect the size of the wetland or how long it lasts on the landscape. Often, the plants and animals found in seasonal wetlands will be opportunistic as they will breed, germinate or grow substantially during the wet periods. Other mobile animals such as birds or kangaroos will visit the seasonal wetlands to take advantage of the available food.
The study was undertaken with the knowledge that many seasonal wetlands have been lost in the area due to land drainage or through the clearing of tall vegetation to convert to pasture. The authors stated that what wasn’t known was whether these wetlands still harboured a diversity of species despite clearing and grazing.
The wetlands in the study were already recognised by the local Catchment Management Authority as being important for birds. There was no information on whether the wetlands were also important for vertebrates (eg. frogs).
Effect of clearing and grazing on seasonal wetlands
To determine the biodiversity of cleared and grazed wetlands the scientists looked at the different types of aquatic insects found in seasonal and permanent pasture wetlands in an agricultural landscape. Aquatic insects were chosen for the study as there is some information already on the types and numbers of aquatic insects found in wetlands across Australia. Therefore, the scientists could review the populations of aquatic insects they found in their study wetlands against data from other wetlands and make some observations about the habitat provided by seasonal wetlands on grazing properties.
The results of the study led to several observations including:
- Permanent and seasonal pasture wetlands are important habitat for aquatic insects.
- Seasonal wetlands had fewer types of aquatic insects than the permanent wetlands, but both still had quite a few species. Up to two thirds of the species found in the permanent wetlands were found in the seasonal wetlands indicating that the seasonal wetlands could be providing expanded area habitat for the aquatic insects during the wet periods.
- The results suggest that wetlands on grazing properties may have conservation value and should be managed to protect them from threatening processes such as drainage.
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