Dieback of rural eucalypts: the effect of stress on the nutritional quality of foliage

Landsberg, J. J.

doi:10.1111/j.1442-9993.1990.tb01024.x

Cited by 29 publications

(12 citation statements)

References 26 publications

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“…Firstly, trees in urban situations are often subject to increased nutrient levels, resulting in increased foliar nutrients (Port and Thompson 1980). Foliar nutrients, in particular nitrogen, can limit factor the performance and fecundity of invertebrate herbivores (White 1984;Landsberg 1990;Peeters 2002). Close proximity to urban areas has subjected remnant vegetation to storm-water and urban run-off, which has led to significant increases in soil nutrient levels within the Sydney basin (King and Buckney 2002).…”

Section: Discussionmentioning

confidence: 99%

Urbanization affects the trophic structure of arboreal arthropod communities

2009

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Urbanization is one of the most significant causes of habitat fragmentation on the planet, resulting in substantial losses of biodiversity and disruptions to ecological processes. We examined the effects of urbanization on the diversity and abundance of arboreal invertebrates in a dominant tree species (Angophora costata) in a highly urbanized landscape in Sydney, Australia, identifying the potential ecological consequences of shifts in diversity. We hypothesized that trophic structure would be influenced by landscape context with a greater richness and abundance of invertebrates in small remnants and edges. Canopy arthropods were sampled via beating from trees in 15 sites in three landscape contexts; five large patches of continuous vegetation, five edges of large patches and five small urban remnants. Trees in large patches supported fewer individuals compared to trees in small urban remnants and edge sites. The composition of assemblages and overall trophic structure also differed between edges and large patches, with a greater abundance of grazing insects in edges. No differences were detected between small urban remnants and edges, suggesting that observed differences might be attributed to an edge effect as opposed to an area effect per se. These changes in trophic structure, revealing a greater abundance of grazing herbivores and a reduced abundance of predators and parasitoids in edge sites, are consistent with work describing elevated levels of herbivory in edges of remnant vegetation. Future management of remnant urban vegetation and associated biodiversity Urban Ecosyst (requires not only an understanding of how trophic status influences the extent of responses by arboreal invertebrate communities, but also how these will affect ecosystem functioning.

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Section: Discussionmentioning

confidence: 99%

Urbanization affects the trophic structure of arboreal arthropod communities

2009

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“…Fragmentation, changed disturbance regimes (particularly fire and logging), and pathogens are implicated (Wardell-Johnson and Lynch 2005, this issue). Changes in nutrients and other soil constituents, climatic regimes and hydrological factors have also been implicated in BMAD and other forms of eucalypt decline associated with insects (White 1969;Landsberg 1990;Landsberg et al 1990). There has been no attempt to unravel the various competing disturbance factors (although see Landsberg and Wylie 1991), with some literature relying on anecdotal evidence and taking an advocatory approach to the problem.…”

Section: Indirect and Direct Factors Associated With Functional Scalementioning

confidence: 99%

A review of eucalypt dieback associated with bell miner habitat in south-eastern Australia

Wardell‐Johnson

Stone

Recher³

et al. 2005

Australian Forestry

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SummaryWe aim to assess current knowledge, and identify gaps in knowledge concerning bell-miner-associated dieback (BMAD) in south-eastern Australia. We review BMAD as a form of forest dieback, and bell miner and psyllid interrelations. We then consider indirect and direct causal factors associated with local functional scales (tree crown), and finally, indirect and direct causal factors associated with broader functional scales (forest stand and landscape processes). This paper emphasises published literature and is a summary of a more detailed report prepared for the BMAD working group which explicitly included personal communications with many researchers, managers and members of conservation groups and the timber industry. We conclude that BMAD is a significant threat to the sustainability of the moist eucalypt forests of north-eastern NSW and south-eastern Queensland, and to biodiversity conservation at a national scale. There are serious deficiencies in the information base for most BMAD issues. While there are clear interactions between bell miners and psyllids, there are many other, less well quantified interactions that may be of greater significance to the development of the problem. We suggest that management and research efforts towards solutions urgently target disturbances that lead to changes in forest canopy structure, but there is unlikely to be a single or simple management solution. An integrated management program will be necessary as concentration on particular management regimes in isolation is unlikely to resolve the BMAD problem because BMAD is associated with interacting disturbances.

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“…This difference in dietary quality does not appear to be genetically determined (Landsberg 1990b). It may be partly due to differences in the local environments ofthe trees, but the nature of any such difference is not clear.…”

Section: Introductionmentioning

confidence: 95%

“…While differences in soil fertility have been measured, they have not always been consistent. In the southern tablelands of New South Wales, soils under dieback trees were more fertile than those under healthy trees (Landsberg 1990b;Landsberg et al 1989), but in south-eastern Queensland, soils under dieback trees were less fertile (Landsberg & Wylie 1983).…”

Section: Introductionmentioning

confidence: 97%

Dieback of rural eucalypts: Response of foliar dietary quality and herbivory to defoliation

Landsberg

1990

Australian Journal of Ecology

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Rural dieback of Eucalyptus blakeiyi trees growing on pastoral properties near Canberra is associated with chronic defoliation by in.sects. In order to test the effect of defoliation on subsequent herbivory. I artificially defoliated three healthy trees by clipping their terminal branchlets. The foliage that regrew on the clipped trees was nutritionally superior to the foliage it replaced, and was much more heavily damaged by grazing insects. There was a transient increase In the tannin content ofthe regrowth foliage, but this was apparently ineffective in defending it from subsequent herbivory. Compared with the foliage on nearby E. blakeiyi trees that also produced major flushes of leaf growth during the same period, the regrowth on the clipped trees had enhaneed dietaty qualities and suffered more insect damage. Leaf age contributed to many of the differences in dietary quality, but when adjustments were made for the effects of leaf age the same trends remained. Five ofthe nearby trees were suffering from the chronic insect grazing associated with rural dieback, and the other five appeared healthy. The dietary quality of regrowth foliage on the elipped trees was qualitatively more similar to that of foliage on the dieback trees. Thus the chronic herbivory associated with rural dieback may be partly selfperpetuating, given this positive feedback between defoliation and dietary quality, and an apparent absenee of other effective controls on insect populations.

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Dieback of rural eucalypts: the effect of stress on the nutritional quality of foliage

Cited by 29 publications

References 26 publications

Urbanization affects the trophic structure of arboreal arthropod communities

Urbanization affects the trophic structure of arboreal arthropod communities

A review of eucalypt dieback associated with bell miner habitat in south-eastern Australia

Dieback of rural eucalypts: Response of foliar dietary quality and herbivory to defoliation

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