Regenerative Succession of Tristaniopsis laurina and Acmena smithii in Riparian Warm Temperate Rain-Forest in Victoria, in Relation to Light and Nutrient Regimes

Abstract

Tristaniopsis laurina and Acmena smithii often form a dominant association in riparian warm temperate rainforest communities in Victoria. The photosynthetic and morphological responses of seedlings of these species to varied light regimes, and the growth responses of seedlings in different nutrient regimes were examined in the laboratory. Acmena smithii was the most shade tolerant, having the lowest light compensation points, dark respiration rates and greater increases in leaf area ratio under low light conditions. Tristaniopsis laurina consistently demonstrated greater maximum rates of leaf photosynthesis at higher photon flux densities. In response to increased nutrients, T. laurina seedlings showed a marked increase in growth and a decrease in root/shoot ratios, while A. smithii demonstrated relatively small growth increases and showed an increase in root/shoot ratios. These results are discussed in relation to the ecological status of these species within the rainforest communities.