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Population structures of the widespread Australian conifer Callitris columellaris are a bio-indicator of continental environmental change
Citation
Prior, LD and McCaw, WL and Grierson, PF and Murphy, BP and Bowman, DMJS, Population structures of the widespread Australian conifer Callitris columellaris are a bio-indicator of continental environmental change, Forest Ecology and Management, 262, (2) pp. 252-262. ISSN 0378-1127 (2011) [Refereed Article]
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DOI: doi:10.1016/j.foreco.2011.03.030
Abstract
Massive environmental changes have occurred since European settlement of Australia more than 200
years ago. We examined the demographics of Callitris columellaris F. Muell. (Cupressaceae) across
Australia as a potential bio-indicator of environmental change. This species is a widespread obligate
seeder with large reproductive potential but is sensitive to fire and herbivory. We measured variation
in tree size, stem density, basal area, and seedling recruitment among 90 sites that encompassed a wide
range of climates and landscape settings across Australia. Soils from each site were analysed for pH, %C,
% N and %P. We also noted evidence of fire and herbivory. Climate at each site was classified as tropical,
temperate or arid. Case studies and published literature are used to illustrate the contrasting effects
of disturbance in the three climate zones. Climate had a strong influence on stand basal area, density
of juveniles and proportions of seedlings and saplings in a population, as well as on prevailing disturbance
regimes. Structure of Callitris populations was not strongly associated with soil fertility. In the arid
zone overall, and in many individual populations, there were relatively few juveniles and evidence of
a chronic recruitment deficit during the last 100–200 years, consistent with reported adverse effects of
introduced herbivores on Callitris regeneration. By contrast, most tropical and temperate populations
conformed to a negative exponential distribution, consistent with frequent regeneration. Many temperate
sites showed extremely dense juvenile populations. In the tropics, juvenile density is lower, probably
because of frequent, relatively mild fires that kill many juveniles but few adult trees. We conclude that
C. columellaris is a sensitive bio-indicator, and is in decline across much of arid Australia, reflecting the
inherent vulnerability of ecosystems in regions with low productivity.
Item Details
Item Type: | Refereed Article |
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Keywords: | Conifer; Cupressaceae; Fire; Macro-ecology; Semi-arid forest; Stand structure |
Research Division: | Biological Sciences |
Research Group: | Ecology |
Research Field: | Terrestrial ecology |
Objective Division: | Environmental Management |
Objective Group: | Management of Antarctic and Southern Ocean environments |
Objective Field: | Assessment and management of Antarctic and Southern Ocean ecosystems |
UTAS Author: | Prior, LD (Dr Lynda Prior) |
UTAS Author: | Murphy, BP (Dr Brett Murphy) |
UTAS Author: | Bowman, DMJS (Professor David Bowman) |
ID Code: | 72405 |
Year Published: | 2011 |
Web of Science® Times Cited: | 40 |
Deposited By: | Plant Science |
Deposited On: | 2011-08-26 |
Last Modified: | 2012-04-16 |
Downloads: | 5 View Download Statistics |
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