SOIL SEED BANKS OF ADJACENT UNLOGGED RAIN-FOREST TYPES IN NORTH-QUEENSLAND

The size and floristic composition of soil seed banks under four adjacent, unlogged and structurally different rainforest types were assessed by exposing 17 surface soil samples (to 40mm depth) to germination-house conditions. The mean size of the seed bank in the undisturbed forest types was 240 seeds m-2 (s.d. 139). Seeds of secondary species dominated the soil seed banks in all forest types, although weed seeds constituted only 0.6-4.0%. Some forest types had characteristic component secondary species in the buried seed bank. Agglomerative classification and multidimensional scaling analysis of quantitative sample data indicated that the parent structural-environmental forest type was the dominant influence in determining composition of the soil seed banks. Comparisons of the seed banks of the intact rainforest with those of nearby disturbed forests showed the former to be 35 to 50% smaller in total size, and lacking in some distinctive secondary species. It was concluded that disturbance, both within and adjacent to rainforest, may influence soil seed bank compositions, and hence future patterns of regeneration. © 1990, CSIRO. All rights reserved.