Inventory Analysis of Southern New South Wales Rainforest Vegetation

Abstract

In order to survey the rainforest of southern New South Wales a survey design for patchy vegetation was devised. Sample area was reduced by use of the gradsect approach. Two gradsects maximising the altitudinal gradient also ensured recovery of latitudinal information. These were also stratified on the basis of altitude, geology and proximity to coast. Within strata random sampling located patches in which qualitative floristic data were recorded for all vascular species and bryophytes. In a total of 231 plots of 50 x 20 m quantitative floristic, structural and environmental data were recorded. Classification (Bray-Curtis) and ordination (principal coordinates analysis) were employed to indicate patterns and trends in the distribution of rainforest species and types. Three major environmental factors correlated with floristic site groupings. These were altitude, disturbance and soil fertility. Within the less disturbed sites a division separated sites on more fertile soils from the less fertile ones. This division generally correlated with species richness and structural complexity in forest types, with the exception of one complex coastal type, which fell within the low fertility category. Sixteen rainforest types are described although only 12 of these are considered to be of significance, the other four containing a small number of sites and possibly being aberrant stands due to disturbance and local environments. ... It was concluded that the gradsect method provided a sound approach to sampling the patchy rainforest vegetation over the study region, and that stratification to ensure sampling over as wide an environmental range as possible, was justified. Twelve major types of high altitude, low altitude dry or disturbed, and low altitude undisturbed rainforests were recognized. The two highest altitude types, being restricted to southern New South Wales, are of particular importance. Types at lower altitudes are important because they include the southern limits of many of their component species.