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

Ahmad Aldrie Amir, Norman C. Duke

Research output: Contribution to journalArticle

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 m 2 to a maximum area of 474 m 2 with an average (±standard deviation) of 134 ± 102 m 2 . 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.

Original languageEnglish
Pages (from-to)66-80
Number of pages15
JournalEstuarine, Coastal and Shelf Science
Volume222
DOIs
Publication statusPublished - 30 Jun 2019

Fingerprint

canopy gap
canopy gaps
mangrove
canopy
dead wood
seedling growth
seedling
gap dynamics
Avicennia marina
mangrove forests
natural regeneration
regrowth
photosynthetically active radiation
marina
eccentricity
biological processes
leaf area index
Queensland
environmental change
porewater

Keywords

  • Australia
  • Canopy disturbance
  • Canopy gap
  • Gap dynamics
  • Mangrove
  • Moreton bay

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science

Cite this

Distinct characteristics of canopy gaps in the subtropical mangroves of Moreton Bay, Australia. / Amir, Ahmad Aldrie; Duke, Norman C.

In: Estuarine, Coastal and Shelf Science, Vol. 222, 30.06.2019, p. 66-80.

Research output: Contribution to journalArticle

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