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A fire-mediated recruitment bottleneck provides a possible explanation for the coexistence of trees andgrasses in mesic savannas. The key element of this hypothesis is that saplings are particularly vulnerable to fire because they are small enough to be top-killed by grass fires, but unlike juveniles, they take several years to recover their original size. This limits the number of recruits into the adult size classes. Thus savanna vegetation may be maintained by a feedback whereby fire restricts the density of adult trees and allows a grass layer to develop, which provides fuel for subsequent fires. Here, we use results from a landscape-scale fire experiment in tropical Australia, to explore the possible existence of a recruitment bottleneck. This experiment compared tree recruitment and survival over 4 y under regimes of no fire, annual early and annual late dry-season fire. Stemmortality decreased with increasing stem height in the fire treatments but not in the unburnt treatment. Tree recruitment was 76–84% lower in the fire treatments than the unburnt treatment. Such fire-induced stem loss of saplings and reduced recruitment to the canopy layer in this eucalypt savanna are consistent with the predictions of the fire-mediated recruitment bottleneck hypothesis.

Item Type:	Refereed Article
Keywords:	Eucalyptus, fire ecology, Kakadu National Park, monsoonal tropics, stand dynamics
Research Division:	Biological Sciences
Research Group:	Ecology
Research Field:	Terrestrial ecology
Objective Division:	Environmental Management
Objective Group:	Terrestrial systems and management
Objective Field:	Evaluation, allocation, and impacts of land use
UTAS Author:	Prior, LD (Dr Lynda Prior)
UTAS Author:	Bowman, DMJS (Professor David Bowman)
ID Code:	66878
Year Published:	2010
Web of Science® Times Cited:	50
Deposited By:	Plant Science
Deposited On:	2011-02-16
Last Modified:	2011-08-31
Downloads:	636 View Download Statistics