Journal of Tropical Ecology

Table of Contents - 1993 - Volume 9, Issue 01  

Research Article

Growth of tree seedlings in tropical rain forests of North Queensland, Australia

Olusegun O. Osunkoyaa1 p1, Julian E. Asha1, Andrew W. Grahama2 and Mike S. Hopkinsa2

a1 Division of Botany & Zoology, School of Life Sciences, The Australian National University, GPO Box 4, Canberra, ACT 2601, Australia

a2 CSIRO, Division of Wildlife & Ecology, Tropical Forest Research Centre, PO Box 780, Atherton, North Queensland, Australia

Abstract

The effects of forest habitat, canopy light condition, vertebrate herbivory and species mean seed size on growth of tree seedlings were evaluated for six widely different species of North Queensland tropical rain forests. Two forest localities differing in size and rainfall intensity were used for the trial. In each forest, seedlings were transplanted three weeks after germination into small to medium-sized canopy gaps and into the forest interiors, with half protected by cages and the other half unprotected. Growth measurements were made over a period of 16 months. All growth parameters examined differed significantly between the six species. At the end of the study period, for most species, forest site and protection from vertebrates did not affect seedling biomass. For all species, growth was higher in gaps than in forest interior, but most biomass allocation patterns did not differ between the two habitats. This was attributed to the small difference in photosynthetically active radiation (PAR) levels between the two habitats (interior, 0.48–2.53% PAR; gap, 3.58–7.09% PAR). Between species, seedling growth in the forest interior and sensitivity to increasing light were significantly correlated with initial mean seed size. The growth ability of the six species in and out of canopy gaps is discussed in terms of regeneration status of forest tree species.

(Accepted May 07 1992)

KEY WORDS

Correspondence:

p1 Present address: School of Biological Sciences, Leigh Marine Laboratory, University of Auckland, PO Box 349, Warkworth, New Zealand.