Journal of Tropical Ecology



Niche differentiation and regeneration in the seasonally flooded Melaleuca forests of northern Australia


Donald C. Franklin a1c1, Peter S. Brocklehurst a2, Dominique Lynch a2 and David M. J. S. Bowman a1p1
a1 School for Environmental Research, Charles Darwin University, Darwin NT 0909, Australia
a2 Land and Vegetation Unit, Department of Natural Resources, Environment and The Arts, PO Box 30, Palmerston NT 0830, Australia

Article author query
franklin dc   [PubMed][Google Scholar] 
brocklehurst ps   [PubMed][Google Scholar] 
lynch d   [PubMed][Google Scholar] 
bowman dm   [PubMed][Google Scholar] 

Abstract

Gallery and floodplain forests in monsoonal northern Australia are mostly sclerophyllous and dominated by five closely related species of Melaleuca (Myrtaceae) amongst which niche differentiation is unclear. We present a floristic and environmental analysis of ‘the flooded forest’ using data from 340 plots distributed across 450 000 km2 of the Top End of the Northern Territory. Melaleuca argentea was confined to streams and occurred on sandier substrates, whereas M. cajuputi mostly occurred in the near-coastal lowlands on clay soils. The greater basal area of M. cajuputi suggests an association with productive sites. Melaleuca dealbata, M. viridiflora and M. leucadendra occurred on a wide range of soils. More deeply floodprone sites were occupied by M. argentea and M. leucadendra along streams and by M. leucadendra and M. cajuputi on floodplains and in swamps. A general deficiency but occasional abundance of Melaleuca seedlings suggests that regeneration is episodic. Seedlings were more frequent in recently burnt areas and especially where fires had been severe. We propose that Melaleuca forests occur where disturbance by fire and/or floodwater is too great for rain forest to persist, rendering them the wetland analogue to the eucalypts that dominate well-drained portions of the north Australian environment.

(Published Online July 2 2007)
(Accepted March 12 2007)


Key Words: disturbance; episodic regeneration; fire; flood; floodplain forest; gallery forest; niche differentiation; paperbark forests; rain forest; soils.

Correspondence:
c1 Corresponding author. Email: don.franklin@cdu.edu.au
p1 Current address: School of Plant Science, The University of Tasmania, Private Bag 55, Hobart Tas. 7001, Australia