Gemmills Swamp Wildlife Reserve was proclaimed in 1989. It comprises 170 hectares of Red Gum floodplain forest and Tall Spike-Rush wetlands between the urban centers of Mooroopna and Shepparton in the heart of the Shepparton Irrigation Region, Victoria, Australia. While essentially an island in an urban and agricultural landscape, it adjoins State Forest to the north-east and a Flora Reserve to the south.
Historically this wetland would have recieved bi-annual flooding of water derived from a fully vegetated catchment. Today with 85% of water within the Greater catchment diverted for agricultural, domestic and industrial uses, flooding is a rarer event. Minor flooding still occures in wetter years, and major flooding events such as the one in the photo occur about every 10 years. Additionally floodwaters bring the European Carp and weed seed from higher in the catchment.The Reserve is more dependant now on urban drainage. 7 stormwater drains enter the Swamp from its western boundries. Nutrients and debris entering the swamp are altering the vegetation composition as nutrient loving plants such as Azzola, Couch and Paspalam form dense mats around the drains.Typhus species have recently appeared and may be an indication of altered nutrient status. During the 1970,s the Swamp was supplied with river water and supported a large water bird population.
Located so close to two major towns, Gemmills is severely imacted by human lifestyle including, trail bike riders,litter dumping including foreign garden plants, bait and firewood collection and fire.Feral and domestic cats prey on ground animals and birds. Adjacent residents remove vegetation at the rear of their properties, either to improve the view or reduce the snake hazard. Water use on nearby streets adds detergents and oils as well as unsightly refuse. Plant communities have lost major genetic influences by reduced flooding, and gained genetic invasion from the surrounding developed landscape.
Gemmills Swamp forms an infilled depression created by a former Goulburn River sometime before the last ice -age. During the ice age the climate was often much drier. During these dry periods the silted up former water-course was subject to strong south-eastery winds which over a long period of time blew out much of the sediments. The lighter clays were more dispersed and the heavier sand particles remained as sand hills. These sand hills now perform many vital functions for the plants and animals of the floodplain. Sandy rises support our catchments Yellow Box Forest. These are mostly small patches of trees with an open understorey of grasses, decending into rushes and soaks. Silver Wattles, Bacon and Eggs, Billy-Buttons, and Chocolate Lillies were once common to these rises. The sand-hills although very porous, actually preserve large amounts of moisture, which seeps into and through the clay below. The many floodcuttings and hollows surrounding these rises remain filled longer than flood-pools further away. This moisture retention is vital for maintaining productivity, especially in dry years where there are long periods between rains. Firetails, Honeyeaters, Wrens, raise their young very close to these pools. Only a few intact representations of these ecological transition zones between floodplain forest and box forest rises remain.
The sandhills at Mooroopna provide pleasant and shady access to both the Goulburn River and the Gemmills Swamp floodplain. Note how inapropriate use has completly removed the all important understorey. Yellow Box islands and the Grey, White and Red Box trees that are associated with the predominantly Red Gum floodplain are one of our most seriously threatened vegetation classes. This stand here is the most significant in the ecolocically adjacent, State Forest, Wildlife Reserve and Flora Reserve.
While the large rounded hill's themselves remind us of the variation in global climate, the drier adapted plants of the surrounding plains, were insurance against loss of cover. Sadly many of these plants have been lost regionally, and so the systems ability to recover has also been lost. Most of the surrounding plant communities are essentially alien, and a constant source of potential invasion. This places a huge demand on future management.
