Factors influencing species selection for littoral rainforest restoration: Do environmental gradients matter?


  • Robert Kooyman,

  • Maurizio Rossetto

  • Robert Kooyman (Research Associate) and Maurizio Rossetto (Conservation Geneticist) work in collaboration through the National Herbarium of NSW (Botanic Gardens & Domain Trust, Mrs Macquaries Road, Sydney, NSW 2000, Australia. Tel. +61 26684 2806. Email: ecodingo@mullum.com.au, maurizio.rossetto@rbgsyd.nsw.gov.au). This project is part of a larger rainforest research effort the authors are undertaking that includes studies of plant species distributions, population genetics, demographics, and trait dimensions.


Summary  Littoral rainforest in northern New South Wales, Australia, has been severely reduced in area and is now extremely limited in extent. Factors influencing the floristics, species richness and abundance, and relationship of this coastal rainforest community type to other lowland rainforests are explored. The purpose of the study was to provide ecological information to support (i) the development of management recommendations and assist habitat expansion and restoration planning for a coastal site at Lennox Head, in northern New South Wales, and (ii) the implementation of recovery actions for an endangered ecological community and an endangered tree species. Multivariate analysis techniques were used to classify and ordinate sampled sites relative to environmental variables to provide an explanation for current floristic assemblages. Eight locations at varying distances to the coast, and representing a range of soil types, were chosen to test the influence of selected environmental variables. At the broad scale, the results show that proximity to the coast and altitude were generally correlated and represented the most influential variables; soil depth, topographic position and slope were broadly correlated but markedly less influential; disturbance was a significant but independent influence on floristics; and soil type and aspect had the least influence. The study provided insight into the ecological parameters of a range of species suited to the habitat rehabilitation and restoration project, and identified finer-scale floristic patterns at the Lennox site that appear to reflect the influence of environmental variables. In that case, areas in closer proximity to the ocean are dominated by several littoral rainforest and disturbance-related species, and species richness increases relative to distance from the ocean. This highlights the need to be sensitive to landscape variation, and the influence of environmental variables on plant species distributions, and population dynamics and structure, to guide final selection of appropriate plant material for littoral rainforest restoration projects.