Canopy dieback and decline in pink gums, Eucalyptus fasciculosa, F.Muell in the Mt Lofty Ranges and adjoining plains
type: CreativeWork
description: In Australia, widespread decline of Eucalyptus species has been occurring largely since the 1970s. In southern Australia, pink gums (Eucalyptus fasciculosa F. Muell) occur within a restricted area, and have been assigned a conservation rating due to perceived canopy decline. This study aimed to describe the population structure and canopy condition of pink gums in the Mt Lofty Ranges and surrounding plains, and to distinguish between causes of short-term dieback and long-term decline. I hypothesised that decline in pink gum woodlands was most likely to be because of one or more of the following: (1) long-term and continuous mistletoe infection; (2) declining annual rainfall commencing several decades ago, particularly for trees growing in deep sandy soils and (3) reduced groundwater availability that commenced well before 2003. Dieback was most likely to be associated with insect attack. Within the study region, pink gums occupy a wide gradient of rainfall, soil type and topography. A regional survey between 2009 and 2012 recorded that the mean canopy intactness for 2814 pink gums was 70%, but canopy condition varied widely between, and often within, pink gum woodlands. The habitat variables that contributed most to variation in canopy intactness were mistletoe prevalence, followed by insect damage. In almost 30% of populations there were no seedling pink gums. Between 2009 and 2011, mean canopy intactness of 1751 pink gums declined from 71% to 66%, 21 pink gums died, and no recruitment was recorded. Leaf production in pink gums was greatest during the above-average rainfall in the summer of 2010/11. This was followed by localised high levels of gum leaf skeletoniser (Uraba lugens) and lerp (Cardiaspina densitexta). Canopy loss from these insects was concluded to be cyclic and short term. The canopy intactness of 161 pink gums and their mistletoe load, was recorded between 2003 and 2015. The net number of live mistletoes declined by two thirds, with the greatest net…
abstract: In Australia, widespread decline of Eucalyptus species has been occurring largely since the 1970s. In southern Australia, pink gums (Eucalyptus fasciculosa F. Muell) occur within a restricted area, and have been assigned a conservation rating due to perceived canopy decline. This study aimed to describe the population structure and canopy condition of pink gums in the Mt Lofty Ranges and surrounding plains, and to distinguish between causes of short-term dieback and long-term decline. I hypothesised that decline in pink gum woodlands was most likely to be because of one or more of the following: (1) long-term and continuous mistletoe infection; (2) declining annual rainfall commencing several decades ago, particularly for trees growing in deep sandy soils and (3) reduced groundwater availability that commenced well before 2003. Dieback was most likely to be associated with insect attack. Within the study region, pink gums occupy a wide gradient of rainfall, soil type and topography. A regional survey between 2009 and 2012 recorded that the mean canopy intactness for 2814 pink gums was 70%, but canopy condition varied widely between, and often within, pink gum woodlands. The habitat variables that contributed most to variation in canopy intactness were mistletoe prevalence, followed by insect damage. In almost 30% of populations there were no seedling pink gums. Between 2009 and 2011, mean canopy intactness of 1751 pink gums declined from 71% to 66%, 21 pink gums died, and no recruitment was recorded. Leaf production in pink gums was greatest during the above-average rainfall in the summer of 2010/11. This was followed by localised high levels of gum leaf skeletoniser (Uraba lugens) and lerp (Cardiaspina densitexta). Canopy loss from these insects was concluded to be cyclic and short term. The canopy intactness of 161 pink gums and their mistletoe load, was recorded between 2003 and 2015. The net number of live mistletoes declined by two thirds, with the greatest net…
author: Croft, Sonia Julie
keywords: Eucalyptus, fasciculosa, canopy decline, dieback, Amyema miguelii
date published: 2017
date modified: 2026-07-24T00:50:36Z
provider: University of Adelaide
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Adelaide

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2440/111991

PropertyValue
property ID: DOI
value: 10.4225/55/5af39b2469af8