Importance of drought on the distribution of the birds nest fern, Asplenium nidus, in the canopy of a lowland tropical rainforest in north-eastern Australia

Freiberg, Martin, and Turton, Stephen M. (2007) Importance of drought on the distribution of the birds nest fern, Asplenium nidus, in the canopy of a lowland tropical rainforest in north-eastern Australia. Austral Ecology, 32 (1). pp. 70-76.

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Abstract

The birds nest fern, Asplenium nidus, contributes greatly to the epiphytic biomass in the canopies of both south-east Asia and tropical north Queensland rainforests. It is generally believed that their abundance and their capacity to store water is an important feature for habitat fragmentation in the canopy. We investigated the microclimate of A. nidus and the effects of severe drought periods on the A. nidus population over a 20-year period, hypothesizing that water availability is the most important factor controlling the population under drought conditions. One of two neighbouring A. nidus plants of the same size and age was irrigated artificially before, during and after a significant dry period in 2000. By monitoring the microclimate within and around both ferns we were able to estimate that four continuous weeks of rainless weather completely dried out the accumulated humus of the non-irrigated A. nidus fern. Prolonged dry periods were shown to kill the roots of A. nidus, which attach the fern to the bark and eventually the affected A. nidus on verticals stems fell to the ground. Periods longer than 8 weeks may even kill adult plants sitting in more protected branch forks. Analysis of the whole A. nidus population within the 1-ha Canopy Crane plot and the determination of the morphological age of all plants enabled an evaluation of the historical development of the population. The oldest plant originated in 1985, just 1 year after the longest recorded drought for the site. We suspect that the 1984 drought killed every A. nidus plant within the study plot. Years with low recruitment coincide with years with long drought periods.

Item ID: 2305
Item Type: Article (Refereed Research - C1)
Keywords: Asplenium nidus; canopy; epiphyte; microclimate; microhabitat
ISSN: 1442-9993
Date Deposited: 09 Jun 2009 06:09
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 50%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060208 Terrestrial Ecology @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 51%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960506 Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments @ 49%
Citation Count from Web of Science Web of Science 6
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