Distinct characteristics of canopy gaps in the subtropical mangroves of Moreton Bay, Australia

Amir, A. Aldrie, and Duke, Norman C. (2019) Distinct characteristics of canopy gaps in the subtropical mangroves of Moreton Bay, Australia. Estuarine, Coastal and Shelf Science, 222. pp. 66-80.

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Abstract

Mangroves often form extensive closed forests characterised by the occurrence of canopy gaps consisting of a group of standing dead trees. This article describes the physical characteristics, micro-environmental changes and the regrowth pattern of the naturally created unique circular canopy gaps in the subtropical Avicennia marina mangroves of Moreton Bay, Southeast Queensland, Australia. A survey on 52 canopy gaps was carried out to quantify the size and shape of canopy openings. We found that gap size ranged from a minimum area of 27 m2 to a maximum area of 474 m2 with an average (±standard deviation) of 134 ± 102 m2. All of the gaps surveyed were circular in shape with the eccentricity of length and width between 0.7 and 1.3. Once a canopy gap is created, the forest physical and biological processes are altered compared with the surrounding forest, such as in an increase in the potential photosynthetic active radiation (PPAR) and canopy openness, and a decrease in leaf area index (LAI). We found that canopy openings also had a significant effect on sediment pore water temperature but not on salinity and pH. The sudden increase in the amount of light following canopy opening stimulated rapid growth of seedlings which were available for the opportunity to take the place of the dead trees. Gap Closure Index (GCI) is introduced to illustrate surveyed gaps in the context of vertical growth of seedlings to fill up gap space to reach the site maximal canopy height, thus demonstrating the phases of gap dynamics in the natural regeneration of the subtropical monospecific mangrove forest.

Item ID: 57963
Item Type: Article (Research - C1)
ISSN: 1096-0015
Keywords: mangroves; canopy; disturbance; gap; recovery; rehabilitation
Copyright Information: © 2019 Elsevier Ltd. All rights reserved.
Funders: University of Queensland (UQ), Ministry of Higher Education, Malaysia (MoHE)
Projects and Grants: UQ University Research Grant, MoHE FRGS/1/2017/WAB07/UKM/02/1
Date Deposited: 15 Apr 2019 05:51
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050207 Environmental Rehabilitation (excl Bioremediation) @ 40%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 40%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment @ 20%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 40%
96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960609 Sustainability Indicators @ 20%
96 ENVIRONMENT > 9606 Environmental and Natural Resource Evaluation > 960603 Environmental Lifecycle Assessment @ 40%
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