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

Abstract

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.

The Influence of Avian Biodiversity and a Weedy Understorey on Canopy Arthropod Assembly

“…Furthermore, the increase in insect abundance in areas where bell miners are present may indicate that a variety of herbivorous insects are responsible for dieback, not only psyllids as previously suggested e.g. [45] [70].…”

“…However, psyllid nymphs, that produce a sugaryprotective coating and feed on the sap of leaves, have been implicated in increased levels of damage in trees, particularly in association with bell miners [12] [44]. This relationship is an extreme example of creating exclusion zones as it has been associated with tree death, known as bell miner associated dieback [11] [45]. Yet, little is known about the top-down effects of bell miners on the insect populations in their territories.…”

Ecology of Honeyeaters (Meliphagidae) in Western Australian Eucalypt Woodlands I: Resource Allocation Among Species in the Great Western Woodland During Spring

“…Not every location was sampled in all years, or for the same lengths of time. We studied birds variously from late August to midOctober at Yellowdine in 1997Yellowdine in , 2001Yellowdine in , 2005Yellowdine in -7, and 2010Widgiemooltha 2005-7;Norseman North 2006-8, 2010and, Norseman West 2003, 2005-8, 2010.…”

“…In addition, some species of honeyeaters (Meliphagidae) exclude other birds from the habitats they occupy influencing the composition of avian communities and the distribution of species on a landscape scale (Loyn et al 1983;Grey et al 1998;Wardell-Johnson et al 2005). Such behaviour changes the abundances and kinds of plant-eating arthropods, thereby affecting the health of plants and entire ecosystems (Loyn et al 1983;Grey et al 1998;Wardell-Johnson et al 2005).…”

Plant Invasions: Symptoms and Contributors Rather Than Causes of Environmental Degradation

“…Declining stands often develop dense understoreys of a few native or exotic shrubs and decline has sometimes been attributed to reduced water and nutrient status as a result of competition from these "invasive" understoreys [5,6]. However several studies have shown that soil water and nitrogen status is increased in declining stands, and trials of understorey removal have failed to ameliorate declines [7].…”