Impacts of agricultural land use on the floristics, diversity and life-form composition of a temperate grassy woodland

Abstract

This opportunistic study examines the impacts of cropping and grazing management on a eucalypt grassy woodland in northern Victoria. The woodland is an area of uniformity in abiotic attributes, and with significant anecdotal similarity in pre-European floristic composition and abundance. Permanent vegetation quadrats were established within the now named Dookie Bushland Reserve, a 270 ha remnant of White and Grey Box grassy woodland located at Dookie College in northern Victoria. Density and cover for all species, as well as life form type, were evaluated within quadrats in 1992, when agricultural land uses ceased and conservation management was instigated. Results indicate that agricultural impact over a 27 year period had contributed to significant declines in the number and cover of indigenous species, and had resulted in the significant increase in the number and cover of introduced species. The loss of shrub species, juvenile eucalypts, and the dominance of tussock-forming indigenous grasses with increased agricultural impact was observed. Individual species responded differently to increased agricultural impacts. Some species, particularly non-tussock forming indigenous grasses and introduced annuals, were promoted in establishment and cover by increased impact, while others, most notably Orchidaceae and Liliaceae, were intolerant of any impact. Certain groups of indigenous species, particularly the Asteraceae and tussock forming indigenous grasses, were reduced significantly in cover by increasing impact. Grazing increased proportions of therophytic (annuals) and/or hemicryptophytic (rosette-forming) forbs, while lesser impacted sites contained a greater diversity of forbs, greater evenness across life form types, and greater proportions of perennial phanerophytes, chamaephytes and cryptophytes, and with fewer therophytes.