Pohlman, Catherine, and Goosem, Miriam (2007) The Effects of Severe Tropical Cyclone Larry on Rainforest Vegetation and Understorey Microclimate Adjacent to Powerlines, Highways and Streams in the Wet Tropics World Heritage Area. Report. Reef & Rainforest Research Centre, Cairns, QLD.

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Abstract

Interactions between natural and anthropogenic disturbance may affect the physical structure and species composition of plant communities. Forest fragmentation as a result of human activities has the potential to alter the ecological responses of remaining areas of forest to natural disturbances such as cyclones, fires or droughts. In particular, trees at the forest edge may be exposed to greater levels of physical stress and wind damage than trees within continuous forest. Elevated levels of tree damage and mortality have been reported near the edges of tropical forest fragments in central Amazonia, apparently in response to a combination of increased moisture stress and greater wind turbulence. Similarly, elevated levels of wind throw and tree mortality near forest edges have been reported in boreal forests, temperate forests and neotropical rainforests, although other studies have reported no increase in wind throw or decreased wind throw near forest or plantation edges. There have been relatively fewer studies of the effects of cyclones and intense storms on vegetation damage in fragmented forests, although elevated levels of cyclone damage to trees have been reported for rainforest edges in northeastern Australia.

Even less is known about the effects of linear infrastructure clearings on the disturbance regimes and ecology of adjacent forest. Tree mortality may be elevated near the edges of such clearings in tropical rainforest in non-cyclonic conditions. However, it is not known whether increased wind exposure at the edges of linear clearings increases rates of vegetation damage and mortality in either normal weather conditions or during intense storms and tropical cyclones. Although there have been anecdotal reports of increased cyclone damage to rainforest near roads and railways in northeastern Australia, the relationship between proximity to linear clearings and cyclone damage has never been directly examined. If severe wind storms do lead to elevated levels of tree damage and mortality near powerline edges, this may have implications for the dynamics (recruitment, growth and mortality rates) of rainforest tree communities and subsequently, their species composition and diversity.

On 20 March 2006, Severe Tropical Cyclone Larry passed directly over the Wooroonooran National Park in the Wet Tropics World Heritage Area of northeastern Queensland. Research sites had previously been established along the Kareeya to Innisfail powerline, along the Palmerston Highway and along Henrietta Creek; all were within the path of the most destructive core of the cyclone. Initial reconnaissance indicated that these sites were severely damaged (although not completely devastated) and that most of the original site markers had survived the cyclone. This provided a rare opportunity to compare measurements taken before the cyclone with those taken after the cyclone, and to determine whether severe storm damage is greater near the edges of powerline clearings (as well as highway clearings and natural watercourses) than in the rainforest interior.

Two research questions were investigated: Is cyclone damage to trees and saplings greater near the edges of linear canopy openings (powerline clearings, highways and watercourses) that in the rainforest interior?

What are the subsequent changes in understorey microclimate (light intensity, air temperature and humidity, soil temperature and moisture and wind speed) near the edges of linear canopy openings?

The findings of this study, along with management recommendations, are presented in this report.

Item ID:	17678
Item Type:	Report (Report)
ISBN:	978-1-921359-12-5
Related URLs:	Organisation
Funders:	Marine and Tropical Sciences Research Facility, Powerlink QLD, The Rainforest Cooperative Research Centre, The School of Tropical Environmental Studies and Geography, James Cook University
Projects and Grants:	MTSRF Project 4.9.3 - Impacts of urbanisation on North Queensland environment: management and remediation
Date Deposited:	21 Jan 2013 04:25
FoR Codes:	05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 35% 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060202 Community Ecology (excl Invasive Species Ecology) @ 30% 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 35%
SEO Codes:	96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960806 Forest and Woodlands Flora, Fauna and Biodiversity @ 35% 96 ENVIRONMENT > 9613 Remnant Vegetation and Protected Conservation Areas > 961306 Remnant Vegetation and Protected Conservation Areas in Forest and Woodlands Environments @ 35% 97 EXPANDING KNOWLEDGE > 970105 Expanding Knowledge in the Environmental Sciences @ 30%
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