Ceratocystis atrox sp. nov. associated with Phoracantha acanthocera infestations on Eucalyptus grandis in Australia

Ceratocystis spp. include important pathogens of trees as well as apparently saprophytic species. Four species have been recorded on Eucalyptus grandis in Australia, of which only one, C. pirilliformis Barnes and M.J. Wingf., is known to be pathogenic. A recent survey of pests and diseases of Eucalyptus trees in northern Queensland revealed a species of Ceratocystis associated with the tunnels made by the aggressive wood-boring insect Phoracantha acanthocera (Macleay) (Cerambicydae: Coleoptera). The aim of the present study was to identify the fungus based on morphological characteristics and comparisons of DNA sequence data for three gene regions. The fungus peripherally resembles C. fimbriata Ell. and Halst. but differs from this species most obviously by having much darker mycelium, longer ascomatal necks, segmented hyphae and an absence of aleuroconidia. Comparisons of combined sequence data confirmed that the Ceratocystis sp. from P. acanthocera represents an undescribed taxon, which is provided with the name Ceratocystis atrox sp. nov. C. atrox appears to have a close relationship with P. acanthocera, although its role in the biology of the insect is unknown and its pathogenicity has not been considered.

Kirramyces viscidus sp. nov., a new eucalypt pathogen from tropical Australia closely related to the serious leaf pathogen, Kirramyces destructans

Kirramyces destructans is a serious pathogen causing a leaf, bud and shoot blight disease of Eucalyptus plantations in the subtropics and tropics of South-East Asia. During surveillance of eucalypt taxa trials in northern Queensland, symptoms resembling those of K. destructans were observed on Eucalyptus grandis and E. grandis × E. camaldulensis. Phylogenetic and morphological studies revealed that the Kirramyces sp. associated with these symptoms represents a new taxon described here as K. viscidus sp. nov., which is closely related to K. destructans. Plantation assessments revealed that while E. grandis from the Copperload provenance, collected in northern Queensland, recovered from disease, E. grandis × E. camaldulensis hybrids from South America were highly susceptible to infection by K. viscidus and are not recommended for planting in northern Queensland. Preliminary results suggest the fungus probably originates from Australia. K. viscidus is closely related to K. destructans and causes a disease with similar symptoms, suggesting that it could seriously damage Australian eucalypt plantations, especially those planted off-site.

Performance of seven hardwood species underplanted to Pinus elliottii in south-east Queensland

Seven hardwood species were tested as underplants under Pinus elliottii plantations on the coastal lowlands of south-east Queensland. The species tested were: Flindersia brayleyana (F. Muell) (Queensland maple), F. australis (R. Br.), (crow's ash), Swietenia macrophylla (King) (American mahogany), Grevillea robusta (A. cunn) (southern silky oak), Elaeocarpus grandis (F. Muell) (silver quandong), F. ifflaiana (F. Meull) (Cairns hickory) and Ceratopetalum apetalum (D. Don) (coachwood). Most species (except E. grandis) established successfully but slowly. Underplants suffered 9-16% mortality during thinning of the overstorey. By 2004 when aged c. 38 years, four underplanted species; F. brayleyana, S. macrophylla, F. ifflaiana and E. grandis, had attained predominant heights of 20 m and mean diameter at breast height of 25 cm or better. The presence of underplants increased total site productivity by up to 23% and did not have any detrimental effect on the development of the overwood.This experiment has demonstrated that some rainforest species will survive and grow healthily as underplants in exotic pine plantations plus produce small merchantable logs within a 38 year rotation. The results also indicated the importance of correct species selection if an underplanting option is to be pursued as some species have been a complete failure (notably G. robusta).

Determination of specific leaf area of some commercially useful sub-tropical hardwood species

Variability of specific leaf area (SLA) across taxa, sites and crown zones was determined for four sub-tropical hardwood species, Eucalyptus grandis, E. cloeziana, E. argophloia and Corymbia citriodora ssp. variegata, growing in south-eastern Queensland. Mean SLA values were stable amongst those taxa sampled on dry sites but varied markedly between provenances of E. grandis on a moist site. Mean SLA did not vary significantly with crown zone in any of these four sub-tropical eucalypts, which is in contrast to that observed in temperate species, both in Australia and overseas. A provenance of E. cloeziana from a moist coastal site exhibited the largest SLA of all taxa studied.

Growth and physiological response of six Australian rainforest tree species to a light gradient

An understanding of growth and photosynthetic potential of subtropical rainforest species to variations in light environment can be useful for determining the sequence of species introductions in rainforest restoration projects and mixed species plantations. We examined the growth and physiology of six Australian subtropical rainforest tree species in a greenhouse consisting of three artificial light environments (10%, 30%, and 60% full sunlight). Morphological responses followed the typical sun-shade dichotomy, with early and late secondary species (Elaeocarpus grandis, Flindersia brayleyana, Flindersia schottiana, and Gmelina leichhardtii) displaying higher relative growth rate (RGR) compared to mature stage species (Cryptocarya erythroxyion and Heritiera trifoliolatum). Growth and photosynthetic performance of most species reached a maximum in 30-60% full sunlight. Physiological responses provided limited evidence of a distinct dichotomy between early and late successional species. E. grandis and F brayleyana, provided a clear representation of early successional species, with marked increase in Am in high light and an ability to down regulate photosynthetic machinery in low light conditions. The remaining species (F. schottiana, G. leichhardtii, and H. trifoliolatum) were better represented as failing along a shade-tolerant continuum, with limited ability to adjust physiologically to an increase or decrease in light, maintaining similar A(max) across all light environments. Results show that most species belong to a shade-tolerant constituency, with an ability to grow and persist across a wide range of light environments. The species offer a wide range of potential planting scenarios and silvicultural options, with ample potential to achieve rapid canopy closure and rainforest restoration goals.

Modelling predicts positive and negative interactions between three Australian tropical tree species in monoculture and binary mixture

Computer modelling promises to be an important tool for analysing and predicting interactions between trees within mixed species forest plantations. This study explored the use of an individual-based mechanistic model as a predictive tool for designing mixed species plantations of Australian tropical trees. The `spatially explicit individually based-forest simulator' (SeXI-FS) modelling system was used to describe the spatial interaction of individual tree crowns within a binary mixed-species experiment. The three-dimensional model was developed and verified with field data from three forest tree species grown in tropical Australia. The model predicted the interactions within monocultures and binary mixtures of Flindersia brayleyana, Eucalyptus pellita and Elaeocarpus grandis, accounting for an average of 42% of the growth variation exhibited by species in different treatments. The model requires only structural dimensions and shade tolerance as species parameters. By modelling interactions in existing tree mixtures, the model predicted both increases and reductions in the growth of mixtures (up to +/-50% of stem volume at 7 years) compared to monocultures. This modelling approach may be useful for designing mixed tree plantations.

Potential for using through-boring to improve groundline treatment of Australian wood species: A preliminary study.

An aging electricity distribution system and reduced availability of naturally durable tropical hardwoods in Australia will combine in the next decade to produce a major shortage of poles. One approach to mitigating this shortage is to utilize lower durability species and improve the penetration of preservatives into the refractory heartwood by introducing additional pretreatment processes. A potential method for improving preservative penetration in the critical ground-line zone is through-boring. This process, in which holes are drilled through the pole perpendicular to the grain in the ground-line zone, is widely used in the western United States for treatment of Douglas-fir and may be Suitable for many Australian wood species. The potential for improving heartwood penetration in eucalypts with alkaline-copper-quaternary (ACQ) compound was assessed on heartwood specimens from four species (Eucalyptus cloeziana F.Muell., E. grandis W.Hill ex Maiden, E. obliqua L'Her. and E. pellita F.Muell.) and Lophostemon confertus (R.Br.) Peter G.Wilson & J.T.Wateril). Longitudinal ACQ penetration was extremely shallow in L. confertus and only slightly better in E. cloeziana. Longitudinal penetration was good in both E. obliqua and E. pellita, although there was some variation in treatment results with length of pressure period. The results suggest that through-boring might be a reasonable approach for achieving heartwood penetration in some Eucalyptus species, although further studies are required to assess additional treatment schedules and to determine the effects of the process oil flexural properties of the poles.

Selecting hardwood taxa for wood and fibre production in Queensland's subtropics.

Optimal matching of species to sites is required for a sustainable hardwood plantation industry in the subtropics. This paper reports the performance and adaptation of 60 taxa (species, provenances and hybrids) across two rainfall zones and a range of soil types in southern Queensland. Specifically, performance of taxa is compared across five replicated taxon–site matching trials at age 6 y. Three trials are in a 1000-mm y–1 rainfall zone of the Wide Bay region near Miriam Vale and two in a drier (about 750 mm y–1) rainfall zone near Kingaroy in the South Burnett region. In the higher-rainfall zone, the taxa with the fastest growth in the three trials at age 6 y were Corymbia citriodora subsp. variegata Woondum provenance, which ranked 1st, 6th and 5th respectively; E. longirostrata Coominglah provenance, ranked 3rd, 2nd and 3rd; and two sources of E. grandis, Copperlode provenance (ranked 4th and 1st) and SAPPI seed orchard (ranked 6th and 4th), which were planted in only two of the three trials. Similarly, in the lower-rainfall zone, E. grandis and its hybrids appear promising from the 6-y growth data., This excellent early growth, however, has not continued in either rainfall zone, with these taxa, 8 y after planting, now showing signs of stress and mortality. Based on trial results in these two rainfall zones, the taxon that appears the most promising for sustainable plantation development with high average annual volume index values and low incidence of borer attack is Corymbia citriodora subsp. variegata (6.7 m³ ha–1). Eucalyptus grandis and E. longirostrata both have better average annual volume indexes (8.2 m³ ha–1 and 7.4 m³ ha–1 respectively) but are very susceptible to borer attack. The current and long-term productivity and sustainability of plantation forestry in these rainfall zones is discussed. Further, the implications of predicted climate change (particularly reduced rainfall) for growing trees for fibre production and carbon sequestration are explored.

Teratosphaeria pseudoeucalypti, new cryptic species responsible for leaf blight of Eucalyptus in subtropical and tropical Australia

Sub-tropical and tropical plantations of Eucalyptus grandis hybrids in eastern Australia have been severely affected by anamorphs of Teratosphaeria (formerly Kirramyces) causing a serious leaf blight disease. Initially the causal organism in Queensland, Australia, was identified as Teratosphaeria eucalypti, a known leaf parasite of endemic Eucalyptus spp. However, some inconsistencies in symptoms, damage and host range suggested that the pathogen in Queensland may be a new species. Isolates of T. eucalypti from throughout its known endemic range, including Queensland and New Zealand, where it is an exotic pathogen, were compared using multiple gene phylogenies. Phylogenetic studies revealed that the species responsible for leaf blight in Queensland represents a new taxon, described here as Teratosphaeria pseudoeucalypti. While the DNA sequence of T. pseudoeucalypti was more similar to T. eucalypti, the symptoms and cultural characteristics resembled that of T. destructans. The impact of this disease in central Queensland has increased annually and is the major threat to the eucalypt plantation industry in the region.

Durability of Queensland Plantation Hardwood Timbers

Establishing the natural durability of Queensland plantation hardwoods including Corymbia citriodora, Eucalyptus cloeziana, Eucalyptus grandis, Eucalyptus microcorys and Eucalyptus pellita.

The suitability of plantation thinnings as vineyard posts.

The aim of this project was to investigate the suitability of thinnings from a range of plantation species for use as vineyard posts. The hardwood plantation species examined were Eucalyptus grandis, E. globulus, E. pilularis, E. dunnii, E. cladocalyx and Corymbia maculata, while Acacia mearnsii was obtained from natural regrowth. The softwood plantation species were P. elliottii, P. radiata and Araucaria cunninghamii. Variables examined included: three air drying regimes; microwave conditioning of E. grandis and E. globulus; two preservative treatments for hardwoods (alkaline copper quaternary compound (ACQ) and pigment emulsified creosote (PEC)); and two preservative treatments for softwood species (ACQ and, for Pinus radiata copper chromium arsenic (CCA)). A further aim was to install treated posts in commercial vineyards for demonstration purposes. From an earlier trial of three hardwood species treated with PEC, demonstration posts previously installed were also to be inspected annually for three years, and any movement of polycyclic aromatic hydrocarbons (PAH) from the posts monitored.

Species-site matching in mixed species plantations of native trees in tropical Australia

Mixed species plantations using native trees are increasingly being considered for sustainable timber production. Successful application of mixed species forestry systems requires knowledge of the potential spatial interaction between species in order to minimise the chance of dominance and suppression and to maximise wood production. Here, we examined species performances across 52 experimental plots of tree mixtures established on cleared rainforest land to analyse relationships between the growth of component species and climate and soil conditions. We derived site index (SI) equations for ten priority species to evaluate performance and site preferences. Variation in SI of focus species demonstrated that there are strong species-specific responses to climate and soil variables. The best predictor of tree growth for rainforest species Elaeocarpus grandis and Flindersia brayleyana was soil type, as trees grew significantly better on well-draining than on poorly drained soil profiles. Both E. grandis and Eucalyptus pellita showed strong growth response to variation in mean rain days per month. Our study generates understanding of the relative performance of species in mixed species plantations in the Wet Tropics of Australia and improves our ability to predict species growth compatibilities at potential planting sites within the region. Given appropriate species selections and plantation design, mixed plantations of high-value native timber species are capable of sustaining relatively high productivity at a range of sites up to age 10 years, and may offer a feasible approach for large-scale reforestation.

Plantation hardwood resource specifications required for planning small log sawing infrastructure investment in Queensland.

Improved information on the product quality of the plantation resource is needed to allow businesses to consider investing in the development of value-adding processing facilities. These facilities are likely to require customised design that optimises the utilisation of future small diameter plantation hardwood logs. This log resource will become available as wood supply in Queensland transitions from native forests to 100% from sustainable plantations. This resource will be controlled by plantations established prior to 2000. A survey of the three main growers (former Forest Enterprises Australia Pty Ltd, former Forestry Corporation of New South Wales, Hancock Queensland Plantation Pty Ltd) revealed that C. citriodora subsp.variegata – CCV (28.0%), Eucalyptus dunnii (27.5%), E. pilularis (23.0%), E. grandis (11.3%) and E. cloeziana –GMS (7.1%) were the most widely planted species in the southern Queensland and northern New South Wales subtropical hardwood estate and would potentially dominate the supply of plantation hardwoods to sawmill processing facilities.

Evidence for different QTL underlying the immune and hypersensitive responses of Eucalyptus globulus to the rust pathogen Puccinia psidii

The rust Puccinia psidii infects many species in the family Myrtaceae. Native to South America, the pathogen has recently entered Australia which has a rich Myrtaceous flora, including trees of the ecologically and economically important genus Eucalyptus. We studied the genetic basis of variation in rust resistance in Eucalyptus globulus, the main plantation eucalypt in Australia. Quantitative trait loci (QTL) analysis was undertaken using 218 genotypes of an outcross F2 mapping family, phenotyped by controlled inoculation of their open pollinated progeny with the strain of P. psidii found in Australia. QTL analyses were conducted using a binary classification of individuals with no symptoms (immune) versus those with disease symptoms, and in a separate analysis dividing plants with disease symptoms into those exhibiting the hypersensitive response versus those with more severe symptoms. Four QTL were identified, two influencing whether a plant exhibited symptoms (Ppr2 and Ppr3), and two influencing the presence or absence of a hypersensitive reaction (Ppr4 and Ppr5). These QTL mapped to four different linkage groups, none of which overlap with Ppr1, the major QTL previously identified for rust resistance in Eucalyptus grandis. Candidate genes within the QTL regions are presented and possible mechanisms discussed. Together with past findings, our results suggest that P. psidii resistance in eucalypts is quantitative in nature and influenced by the complex interaction of multiple loci of variable effect.