Studies in the ecology of the Riverine plain. I. The gilgai microrelief and associated flora

Abstract

The flora of the gilgai microrelief at Deniliquin, N.S.W., is described, and the major vegetation changes over a 4-year period are outlined. Until 1950 the shelf was dominated by chenopodiaceous plants, the depression by perennial grasses, and the puff by annual grasses and herbs. After heavy and persistent winter rainfall in 1951, the depressions remained waterlogged for several months. The perennial grasses died out and were replaced by species of Juncus and Carex and Eleocharis acuta R.Br. With the return to more normal rainfall the earlier flora in the depression is being slowly re-established. From measurements made on the soils it would appear that physical factors are important in determining the species which grow on the shelf, depression, and puff respectively. Some of the factors concerned are: (a) the soil moisture content at which water becomes available to plants, and particularly to seeds; (b) the intensity of soil cracking, which influences seed retention, moisture penetration, and the extent to which root systems are damaged; (c) aeration of the soil.