Eucalypt Plantations In Australia Research Articles

Comparison of the biology, ecology and potential pest impacts of the eucalypt-defoliating leaf beetles <i>Paropsisterna cloelia</i> and <i>Paropsis charybdis</i> (Coleoptera: Chrysomelidae) in New Zealand

Background: Eucalypt species are grown in New Zealand for a variety of purposes. Paropsine leaf beetles (Coleoptera: Chrysomelidae) impact eucalypt plantations in Australia and other countries where eucalypts have become established. Six eucalypt-feeding paropsines from Australia have established in New Zealand to date. Paropsis charybdis Stål is currently regarded as the worst eucalypt pest. Paropsisterna cloelia (Stål) established in New Zealand in 2016 and it remains uncertain whether its potential impacts will exceed those caused by P. charybdis. Methods: In this review, we provide an update on eucalypt insect invasions in New Zealand, summarise available literature on Pst. cloelia, and compare its ecology to P. charybdis, including distribution, host preferences, phenology, and natural enemies. Finally, we identify key areas for future research and give recommendations for integrated pest management. Results: The number of specialist eucalypt-feeding insects has increased to approx. 36 species. The largely overlapping distributions of P. charybdis and Pst. cloelia in Australia indicate a similar climate tolerance; hence Pst. cloelia is likely to spread throughout New Zealand over time. Life history traits and behaviour of Pst. cloelia suggest it has a higher reproductive output and higher survival rate of immature stages than P. charybdis. This could potentially lead to severe defoliation from more frequent population outbreaks of Pst. cloelia, particularly under climatic conditions that induce growth stress in trees. Both species seem to prefer eucalypt species from different sections within the subgenus Symphyomyrtus, indicating a degree of niche separation. Paropsisterna cloelia larvae feed on both flush juvenile and adult leaves of heteroblastic eucalypt species (i.e., producing morphologically different juvenile and adult leaves), which would be of particular concern if it were to invade E. nitens plantations. Conclusions: We believe that Pst. cloelia has the potential to exceed the observed impacts from P. charybdis in New Zealand and cause growth losses in its most preferred eucalypt species. An integrated pest management approach that employs strategies, such as breeding for resistance, choice and siting of species, biological control, and/or pesticide use at set damage thresholds could result in significant economic benefits and resilience. As biocontrol is a long-term solution, other strategies need to be investigated and implemented without delay for the industry to be pre-emptive.

Factors controlling individual branch development during early growth of an experimental plantation of Eucalyptus pilularis in sub-tropical Australia

Branch sizes and their vertical orientation increase progressively further up the lower stem to support a newly developing crown. Diameter at base, orientation, and height up the stem of live branches on the lower 5 m of tree stems were measured several times over 2.5–5.7 years of age in an experimental plantation of blackbutt (Eucalyptus pilularis) in sub-tropical eastern Australia. Stocking density at planting varied over 816–1667 stems ha-1 and rectangularity of planting (ratio of distance between rows to distance between trees within rows) over 1–6. Tree stem diameters, heights and crown dimensions were also measured. The height above ground at which branches emerged from the stem was a primary factor determining their growth; the higher they were, the greater was their diameter and the more vertical their orientation. This was believed to reflect both a need for newer branches to grow larger than older branches, to support greater amounts of foliage as the crowns expanded towards full size, and for branches to be better oriented to seek sunlight as the crowns of surrounding trees also expanded. Secondary factors determining branch size were tree size and spacing between trees, factors that are likely to interact with each other. Larger trees tended to have larger branches, to support more leaf weight in larger crowns. The direction of emergence of branches from stems seemed little affected by tree or stand characteristics at these early stages of tree development. The results did not suggest any need to modify existing pruning regimes that have been developed for fast-growing eucalypt plantations in Australia.

First Report of Puccinia psidii (Myrtle Rust) in Eucalyptus Plantations in Australia.

Puccinia psidii Winter (myrtle rust, eucalyptus rust) is a significant pathogen of Eucalyptus plantations in Brazil, causing reduced growth, stem malformation, and in severe cases, tree death (3). It has a wide host range in the Myrtaceae, with over 445 species in more than 72 genera (4). As such, P. psidii has long been a threat to Australia, where many ecosystems are dominated by Myrtaceae and industries are reliant on myrtaceous hosts, including almost 1 million hectares of eucalypt plantations. In April 2010, P. psidii was detected in Australia (2) and is now established along the east coast from southern New South Wales to far north Queensland (1,5). Although known to cause severe damage to eucalypt seedlings and coppice in native forests (5), it had not been found affecting eucalypt plantations in Australia. Surveys for P. psidii were thus initiated in eucalypt plantations in NSW from the central coast (33°06'40.0″ S, 151°18'13.8″ E) to the NSW-Queensland border, encompassing 55 plantations. Two to four 100-tree transects were conducted per plantation, during spring and summer. Symptoms were first detected in December 2011 in a 6-month-old Eucalyptus agglomerata Maiden plantation on the central coast. Further surveys until summer 2014 identified P. psidii on E. pilularis Sm., E. cloeziana F. Muell., and E. grandis (Hill) Maiden in young plantations from the central coast to the north coast (30°24'20.2″ S, 152°55'57.9″ E) of NSW. Necrotic lesions and yellow pustules typical of P. psidii were present on immature leaves and shoots, often causing leaves to buckle and die. Urediniospores were globose to subglobose, yellowish brown, 15 to 20 × 18 to 23 μm, single-celled, and finely echinulate, with a prominent tonsure on the majority of spores. Teliospores were cylindrical to ellipsoidal with a rounded apex, tan brown, 25 to 45 × 15 to 25 μm, and two-celled, with remnants of a pedicel. These morphological characteristics are consistent with those of P. psidii from Australia and elsewhere (5). Simple Sequence Repeats developed from genome sequencing of an Australian isolate of P. psidii revealed no variation among 15 isolates of P. psidii from Australia and Hawaii, including an isolate from an E. pilularis plantation in NSW (K. S. Sandhu and R. F. Park, unpublished), corroborating the morphological identification. This is the first report of this significant pathogen in eucalypt plantations in Australia. P. psidii was found in only five plantations during the current surveys, in trees 6 months to 2 years old, with only a low incidence (1%) per plantation. Repeat surveys revealed no ongoing disease in the same plantations after trees were three years of age. Moreover, P. psidii was found only in plantations surrounded by native forest stands, which harbor a large reservoir of susceptible hosts, such as Rhodamnia rubescens (Benth.) Miq. The strain of P. psidii that entered Australia is currently not causing serious disease in eucalypt plantations. However, there is a need to continue quarantine restrictions to reduce the chance of another, more aggressive strain of P. psidii entering Australia.

Variability in aggressiveness of Quambalaria pitereka isolates

Quambalaria shoot blight, caused by the fungal pathogen Quambalaria pitereka, is a serious disease of eucalypt plantations in Australia. The aggressiveness of four Q. pitereka isolates was compared on a range of host genera, species, provenances and clones. Isolates differed substantially in their aggressiveness, with two consistently showing higher levels of aggressiveness based on incidence and severity of disease and lesion size. Isolates derived from Corymbia citriodora subsp. variegata (Ccv) and C. torelliana were shown to have a relatively restricted host range, with lesions but no sporulation found on Eucalyptus species, Angophora species other than A. costata and Corymbia species other than Ccv, the host of origin. The level of aggressiveness toward the different provenances of spotted gum and C. torelliana varied between isolates and there was evidence of some isolate × host interaction within provenances of Ccv. The two methods of inoculation used in this study, spray and spot inoculation, gave similar results. However, the fact that the spot inoculation method was labour-intensive was a disadvantage limiting the numbers of isolates and hosts that can be tested.

Modelling growth responses of individual trees to early-age thinning Eucalyptus globulus, E. nitens and E. grandis plantations in northern Victoria

Summary Interest in production of sawlogs from eucalypt plantations in Australia has increased as logging in native forests has declined. Management for sawlog production commonly involves early-age selection and pruning of potential sawlog trees, and thinning. Existing stand-level models developed using data from unthinned plantations, grown primarily for pulpwood, cannot provide accurate estimates of sawlog yield for thinned plantations, and further model development is required. We addressed this issue using an individual-tree distance-independent modelling approach. Data from thinning and pruning experiments at three sites in northern Victoria were analysed, and diameter increment models were estimated for three tested species, Eucalyptus globulus Labili., E. grandis Hill ex Maiden and E. nitens (Deane and Maiden) Maiden. A new model form with use of two indicator variables was designed in this study to compare the growth of sawlog trees selected in thinned treatments with their equivalent cohorts in unthinned treatments. The best variables identified by regression analysis included initial diameter of the target tree, stand age, site index and time since thinning, together with a measure of thinning intensity (the removed basal area ratio) and a measure of inter-tree competition (basal area for the larger trees). Structured in this way, the developed models are flexible for predicting the thinning responses of selected sawlog trees for a wide range of tree size, site and stand conditions, and thinning treatments, leading to more accurate prediction of sawlog yield and associated size class distribution information. This result implies that better decisions on whether to thin may be achieved in plantation management practice. To provide the models with sound statistical properties, nonlinear mixed-model techniques were used to correct for within—and between-subject auto-correlation and heterogeneity of errors. Further study to validate the developed models for a wide range of stand and site conditions, and thinning treatments, using independent data is recommended.

An irrigation-scheduling model for application of saline water to tree plantations

WATSKED is a simple spreadsheet model that uses a water-budgeting approach to schedule irrigation of eucalypt plantations in Australia. The model was developed as part of the Wagga Wagga Effluent Plantation Project (WEPP) in New South Wales, Australia. Pan coefficients (the ratio of water-use to pan evaporation) for 33 reference sites within 10 biogeoclimatic zones were calculated using the Penman–Monteith model calibrated to water-balance measurements in Eucalyptus grandis (flooded gum). The model estimates plantation water-use from these pan coefficients and measured pan evaporation. Simple equations are used to calculate run-off, canopy interception of water during irrigation and rainfall, soil water distribution, and drainage. The model divides the soil into two layers and predicts daily soil water deficit, daily average levels of root-zone soil salinity, and the timing and amount of irrigation and leaching fraction required to control salinity. Input data include pan evaporation, rainfall and applied irrigation, and estimates of basic soil physical characteristics. For prediction of salinity, input data also include estimates of initial average soil salinity, salinity of the irrigation water, threshold and critical soil salinity, and a user-nominated maximum allowable level of soil salinity. The model was tested and performed well at two sites, one under freshwater sprinkler irrigation, and the other under freshwater flood irrigation. Predicted volumetric soil moisture contents at fortnightly intervals were in close agreement with measured values. The model is yet to be tested for scheduling irrigation with saline water.

Fauna conservation in Australian plantation forests – a review

A review of the value for fauna of conifer and eucalypt plantations in Australia is presented. Five key reasons highlight a need for wildlife conservation as part of plantation management. These are: (1) The plantation estate in Australia is set to triple in the coming decades, and where new plantations are located and how they are managed will influence the biota that currently exist in such landscapes. This is particularly critical in many semi-cleared former grazing landscapes where the establishment of new plantations is focused. This is because: (1) (a) native vegetation communities in these areas are poorly represented in the existing reserve system, and, (b) uses such as wood and pulp production need to be balanced with other management values such as wildlife conservation. (2) The maintenance of some elements of the biota within plantations could have benefits for key ecosystem processes like pest control. (3) Although some species cannot be conserved in plantation-dominated landscapes, many species can be through the adoption of (sometimes minor) modifications to forest management. (4) The maintenance (or loss) of biota in plantations is relevant for moves toward ecological standards and the certification of plantations in many parts of the world. And, (5) simple plantation forestry which has a narrow and intensive management focus on producing a forest crop for a limited array of purposes, may not meet societal demands for a range of outputs from plantations in addition to wood and pulp. It also may not be congruent with the principles of ecological sustainability. Our review showed that almost all research undertaken in Australian plantations, both in conifers and eucalypts, highlighted the importance of landscape heterogeneity and stand structural complexity for fauna conservation. At the landscape level, patches of retained native vegetation, strips of riparian vegetation, dams, open and clearing areas can significantly increase the number of native species that occur within plantations. Some species that occur in these areas can also use adjacent planted areas, a result common to conifer and eucalypt plantations. The spatial juxtaposition of stands of varying ages throughout plantation landscapes also can contribute to the maintenance of some populations of native taxa. At the stand level, structural complexity is also important for fauna with many species responding positively to the presence of native understorey plants, the presence of windrowed logs, and logging slash left on the forest floor. The management of plantations to promote landscape heterogeneity and stand structural complexity will, in many cases, involve trade-offs that will influence wood and pulp production. The extent to which this occurs will be dependent on the objectives of plantation management and how far they extend toward the complex plantation forestry model to incorporate social and environmental values in addition to wood and pulp production.

Intra‐plant host selection, oviposition preference and larval survival of Chrysophtharta agricola (Chapuis) (Coleoptera: Chrysomelidae: Paropsini) between foliage types of a heterophyllous host

Abstract 1 Paropsine chrysomelid beetles defoliate commercial eucalypt plantations in Australia. Adults and larvae feed on the same host, with the larval food source determined by the oviposition choice of females. Most eucalypt species are heterophyllous, with their foliage undergoing distinct morphological and chemical changes between adult and juvenile growth.2 The intra‐plant foliage feeding and oviposition preference adults and the larval development of Chrysophtharta agricola were examined using adult and juvenile foliage of a heterophyllous plantation species, Eucalyptus nitens. The foliage types differ in chemistry, toughness, waxiness and timing of production.3 In the field, feeding damage caused by adult beetles was 15% more frequent on adult foliage than on juvenile foliage; however, egg batches were three times more common on juvenile than on adult foliage.4 Oviposition preference for juvenile foliage over adult foliage was confirmed in choice trials in the laboratory, with adult fecundity and longevity not significantly different between foliage types.5 Larval survival, development time and subsequent pupal weight were also unaffected by foliage type, suggesting that neither foliage type is nutritionally superior for adults or for larvae. However, adult foliage was significantly thicker than juvenile foliage and this may prove a physical constraint to larval establishment. Biotic and abiotic factors (including interactions with natural enemies, competition, microclimate and mate location) that may affect patterns of host plant utilization are discussed.

Insect pest problems of eucalypt plantations in Australia

Summary The increased rate of hardwood plantation establishment in Tasmania, mainly of a single species of Eucalyptus, has placed increased emphasis on the need for applied research on insect species causing damage to this resource.

Insect pest problems of eucalypt plantations in Australia

Summary This paper briefly summarises the status of eucalypt plantations in Victoria and identifies the insect pests that can cause severe damage to foliage during the first three years after planting on farmland, before canopy closure and foliage maturation. Also discussed are various factors presumed to predispose such plantations to severe insect attack, the nature of the damage, the present and future pest management options and the associated research. Predominant among economically important insect pests are the Christmas beetles (Anoplognathus chloropyrus and A. hirsutus), leaf beetles (Chrysophtharta agricola, C. variicollis and Paropsis porosa), the Autumn Gum Moth (Mnesampela privata), the Leafblister Sawfly (Phylacteophaga froggatti) and the Wingless Grasshopper (Phaulacridium vittatum). At present control of outbreaks is by spraying insecticide. Environmentally more acceptable multi-pronged control programs are being developed, comprising a mix of compatible preventative and curative genetic, silvicultural, biological and chemical measures. Such programs will be based on a thorough knowledge of the biology and ecology of the target pests in the particular climatic regions where the plantations are located.

Insect pest problems of eucalypt plantations in Australia

Summary An entomological overview of the eucalypt plantation programme being carried out by the Forestry Commission of New South Wales is presented. Some of the insect pests known to damage eucalypt forests and plantations in New South Wales are listed and discussed.

Insect pest problems of eucalypt plantations in Australia

Summary The growing of eucalypts in plantations is very new in South Australia. Few insect problems have been encountered so far though Mnesampela privata and Eriococcus coriaceous have caused considerable damage. Of more recent concern are Tryphocaria acanthocera and Heteronyx elongatus. The more common pests in eucalypt plantations are listed.

Insect pest problems of eucalypt plantations in Australia

Summary Some of the most common and damaging insect pests of eucalypt trees in plantations and in native forests in Queensland are listed and discussed. Principal among these are stem boring longicorns (Tryphocaria), wood moths (Xyleutes, Uzucha), lerp insects (Cardiaspina), scarab leaf beetles (Anoplognathus, Epholcis) and subterranean termites (Coptotermes). Of the listed pests of native forests, phasmatids are the only major group yet to cause damage in plantations here.

Insect pest problems of eucalypt plantations in Australia

Summary The plantation estate of Eucalyptus globulus in Western Australia, though small in relation to hardwood plantations elsewhere, has generally been free of insect problems. Ten insect species have, however, been recorded causing significant, but sporadic, damage. The four most important are Wingless grasshopper, African black beetle, Leafblister sawfly and Spring beetle. The first two have caused mortality though defoliation and bark chewing respectively and the other two height decrement. Preparation and dissemination of an Insect Manual in 1990 has helped co-ordinate the detection of damaging levels of insects and ensure the use of appropriate control measures. The major deficit in knowledge concerns the economic injury levels for insect species in plantations.

Insect pests in intensively-managed eucalypt plantations in Australia: Some thoughts on this challenge to a new era in forest management

Summary The area of intensively-managed eucalypt plantations in Australia is expanding and may increase more rapidly in the next decade. Some of the insect problems associated with these plantations are likely to be different and may even have a greater economic impact than those occurring in native forests. The attitudes of forest managers towards insect problems associated with eucalypt plantations are discussed. The limited knowledge of the ecology of eucalypt-feeding insects in Australia is highlighted and insect problems that have occurred, and those likely to occur in eucalypt plantations, are discussed. The integrated management approach to insect problems in eucalypt plantations is emphasised and important areas for research are identified.