Structural and Floristic Attributes of Recolonizing Species in Large Rain Forest Gaps, North Queensland

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Abstract
This study examines whether structural and floristic attributes of plants recolonizing large gaps (50-200 m width) differ from those of plants in adjacent, mature North Queensland rainforests. Plant attributes were observed in a sequence of contiguous large gaps of increasing age abutting mature simple notophyll vine forst in Lake Eacham National Park, near Atherton, North Queensland, Australia. Certain structural attributes of species inhabiting 7 yr old recolonizing rain forest sites differ significantly from those of intermediate age (50 yr) or mature (100 yr+) forest. From the recent forest edge to older, interior sites, average leaf size increases, and leaves are more commonly sclerophyllous, upward tilting and dorsiventral. The incidence of bird-dispersed species is greatest in the 50 yr site; plants with ant- and passive-dispersal modes decrease toward the older, interior forest sites, while cassoway- and mammal-dispersed species increase. Floristic changes along the age sequence indicate a successional return toward mature forest composition. Alpha diversity is 118 species /0.1 ha for the mature forest, and beta diversity is 6.7 half-changes. Concentration of dominance decreases toward the mature site. The differences in structural features of recolonizing edge species suggest that structural attributes of species in large gaps are not a random subset of the available gene pool.