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Fire regimes in temperate forests and woodlands have changed significantly in Australia since European settlement. We hypothesised that an absence of fire leads to the increased development of woody understorey/ midstorey and that this may be correlated with decreased water and/or nutrient availability in overstorey temperate eucalypts currently declining in health. Sites with a history of being long unburnt or recently (and frequently in the case of Eucalyptus gomphocephala woodland) burnt (relative to median fire intervals for the vegetation type) were established in E. gomphocephala woodland in Western Australia and in Eucalyptus delegatensis forest in Tasmania. In long unburnt sites in both E. gomphocephala woodland and E. delegatensis forest, there was greater percent cover of understorey/midstorey and eucalypts had higher water use efficiency, indicative of greater soil water limitation, as estimated by foliar carbon isotope ratios. In E. gomphocephala woodland foliar Cu and Zn were significantly lower in eucalypts of long unburnt, relative to frequently burnt, sites. In E. gomphocephala woodland, understorey/midstorey (shrub) cover was positively correlated, and foliar copper and zinc levels were negatively correlated to health of overstorey trees. In E. delegatensis forest foliar phosphorus (P) was significantly lower in eucalypts of long unburnt, relative to recently burnt, sites. In E. delegatensis forest moss cover was positively correlated and foliar P was negatively correlated to health of overstorey trees. The understorey/midstorey that develops in the long absence of fire may alter ecological processes that lead to less favourable water- and nutrientrelations in E. gomphocephala woodland and E. delegatensis forest that are associated with decline in crown health. However this study does not definitively show a link between understorey/midstorey vegetation and overstorey tree water- and nutrient-relations. This link will be investigated in future research.

Item Type:	Refereed Article
Keywords:	Eucalyptus; Tree decline; Fire; Plant nutrition
Research Division:	Agricultural, Veterinary and Food Sciences
Research Group:	Forestry sciences
Research Field:	Tree nutrition and physiology
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Forestry
Objective Field:	Native forests
UTAS Author:	Close, DC (Professor Dugald Close)
UTAS Author:	Davidson, NJ (Dr Neil Davidson)
ID Code:	69561
Year Published:	2011
Web of Science® Times Cited:	12
Deposited By:	Agricultural Science
Deposited On:	2011-04-29
Last Modified:	2017-08-25
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