Growth of heath vegetation. II. The seasonal growth of a heath on ground-water Podzol at Wilson's Promontory, Victoria

Abstract

The seasonal growth of a heath on a ground-water podzol in southern Victoria is presented. Seasonal changes in the dry weight of standing vegetation, dry weight of surface roots, and soil moisture were followed. Three phases of growth are obvious. The first phase, shoot growth in late spring-early summer, may be the result of a redistribution of metabolites.

During the second phase, a significant increase in the dry weight of tops may occur; this presumably leads to an increase in evapotranspiration and a decrease in soil moisture. Death of some roots then occurs, followed by abscission of older leaves and death of weaker plants. Any increase in the biomass of tops is thus cancelled in this heath ecosystem.

With reduction in leaf area, evapotranspiration decreases and soil moisture increases. In this third phase in late summer, the root weight increases to approximately that of the previous winter.

Thus the ecosystem maintains a fluctuating equilibrium in root-top biomass from year to year.