The effect of changing irrigation strategies on biodiversity
Abstract
This study demonstrates that where groundwater tables have fallen, rainfall is in deficit and surface flooding occurs less than once every two years, E. largiflorens trees will be in poor condition and are more likely to die. In the absence of sufficient rainfall and groundwater, more frequent flooding is required to maintain E. largiflorens in good condition (less crown death and greater crown density) than would normally be required. Irrigation landuse intensity affects variables that create habitat complexity in woodlands, such as the presence of old and young trees, and the abundance of shrubs such as lignum and sclerolaena. Flow regimes (particularly prior wetting frequency) affect both structure and condition. Two contrasting levels of the effect of irrigation landuse intensity on woodland bird abundance were found. Firstly, a broad scale positive relationship between irrigation water availability and bird abundance at a regional scale; and secondly, a withinΓregion negative effect of very high intensity irrigation landuse upon bird abundance. Site flood history was not related to bird abundance, primarily because of the dominanceof the regional and irrigation landuse intensity effects observed.