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Growth of juvenile and sapling trees differ with both fire season and understorey type: Trade-offs and transitions out of the fire trap in an Australian savanna

Werner, Patricia A. (2011). Growth of juvenile and sapling trees differ with both fire season and understorey type: Trade-offs and transitions out of the fire trap in an Australian savanna. Austral Ecology: a journal of ecology in the Southern Hemisphere,:644-657.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 4 times in Scopus Article | Citations

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IRMA ID 82057923xPUB129
Title Growth of juvenile and sapling trees differ with both fire season and understorey type: Trade-offs and transitions out of the fire trap in an Australian savanna
Author Werner, Patricia A.
Journal Name Austral Ecology: a journal of ecology in the Southern Hemisphere
Publication Date 2011
ISSN 1442-9985   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-84865599483
Start Page 644
End Page 657
Total Pages 14
Place of Publication Australia
Publisher Wiley-Blackwell Publishing Asia
HERDC Category C1 - Journal Article (DIISR)
Abstract Canopy tree populations in mesic savannas are often bimodal with few saplings but many smaller individuals of indeterminate age that repeatedly suffer topkill and regenerate from underground tissues. Little is known about growth rates or mechanisms that allow subadult trees to reach the canopy. The wooded savannas of northern Australia have high frequencies of dry-season fires. In a 32400-m 2 field experiment, 2405 juveniles (<150-cm height) and saplings (150-499cm) of the eucalypt canopy species were individually marked and measured the year prior to fires set in three different seasons and again at the end of the growing season (without fires) a year later. Trees in unburnt plots served as controls. All fire treatments were repeated in plots dominated by the most common understorey, a native annual grass (sorghum) and in plots dominated by perennial native species; these produce different fuels for fires and competitive regimes for young trees. After early dry-season fires, height growth of larger juveniles and all saplings was significantly enhanced, especially in sorghum. After late dry- or wet-season fires, juvenile trees grew well, but all of the small saplings (150- to 299-cm height) were reduced to 'juveniles' and did not recover pre-fire heights but, instead, produced many new basal (coppice) stems. Late, dry-season fires reduced more than 80% of large saplings (300-499cm) to juvenile size in sorghum, whereas in non-sorghum, 60% of the trees grew to poles (500-999cm). The results demonstrate that juvenile and sapling growth responses to fire and the probability of subadult trees reaching the canopy are related to fire-understorey interactions, and suggest that the mechanisms include morphological and carbohydrate storage dynamics which vary with tree size and life history stage. The key to successful management of a sustainable woody canopy lies in the understorey.
Keywords Eucalyptus population dynamics
Fire-understorey interaction
Fire: effect of fire season
Savanna woodland: tree: height growth
Tree: canopy replacement
DOI http://dx.doi.org/10.1111/j.1442-9993.2011.02333.x   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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