Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations of Tasmania,Australia

The genus Mycosphaerella Johanson contains many pathogens capable of causing a severe impact on the growth of susceptible eucalypt species. The lack of knowledge about which species are present in Tasmania and their potential risk to the plantation industry prompted this study into the Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations in Tasmania. A total of 36 plantation and five road verge sites of E. globulus and E. nitens were sampled. Five Mycosphaerella species and three species from associated anamorph genera were isolated and identified in Tasmania; Mycosphaerella nubilosa, Mycosphaerella cryptica, Mycosphaerella tasmaniensis, Mycosphaerella grandis, Mycosphaerella vespa, Coniothyrium ovatum, Sonderhenia eucalypticola and Sonderhenia eucalyptorum. The most frequently isolated species with the highest incidence and severity of infection were M. cryptica and M. nubilosa. These two species appear to have the greatest potential to damage juvenile eucalypt plantations in Tasmania. A link between Mycosphaerella vespa and Coniothyrium ovatum is described for the first time.     

Factors influencing the production of structural plywood in Tasmania,Australia from Eucalyptus nitens rotary peeled veneer

Harvested logs supplied from five fibre-managed Eucalyptus nitens plantation coupes with different growing environments were assessed for quality and stiffness. Billets extracted from the logs were rotary peeled for veneer. When averaged across the five coupes, 30% of veneer recovered could be used directly in structural plywood production and an additional 20–25% could be used after further processing. In visual assessment most veneer was assigned an Australian/New Zealand Standard AS/NZS2269.0:2012 Quality D. Acoustic testing during processing showed veneer peeled from a drier and lower elevation coupe had significantly higher dynamic MOE values than veneer processed from logs harvested from wetter higher elevation coupes. To examine the utility of the E. nitens peeled veneer in the production of structural plywood, it was combined with veneer of a known higher stiffness, rotary peeled from regrowth forest Tasmanian oak species logs. Structural seven-ply panels were manufactured from the veneer prepared in three different ply arrangements. Mechanical testing of the panels in accordance with AS/NZS2269.0:2012 showed that an F17 target stress-grade panel product of 83% E. nitens and 17% Tasmanian oak species could be produced, if E. nitens veneer of higher stiffness were selected from veneer segregated by estimated dynamic Modulus of Elasticity value. Panels with 50% E. nitens and 50% Tasmanian oak veneer could be produced by selecting E. nitens veneer of lower stiffness after segregation. In the majority of panels tested stress-grade rating was limited by perpendicular bending strength. Outcomes from the study indicate that structural plywood can be manufactured using differing proportions of E. nitens veneer, rotary peeled from fibre-managed plantations, provided it can be segregated into stiffness categories and selected to achieve a target stress-grade.     

Mycosphaerellaceae and Teratosphaeriaceae associated with Eucalyptus leaf diseases and stem cankers in Uruguay

Mycosphaerella leaf diseases represent one of the most important impediments to Eucalyptus plantation forestry. Yet they have been afforded little attention in Uruguay where these trees are an important resource for a growing pulp industry. The objective of this study was to identify species of Mycosphaerellaceae and Teratosphaeriaceae resulting from surveys in all major Eucalyptus growing areas of the country. Species identification was based on morphological characteristics and DNA sequence comparisons for the Internal Transcribed Spacer (ITS) region of the rDNA operon. A total of ten Mycosphaerellaceae and Teratosphaeriaceae were found associated with leaf spots and stem cankers on Eucalyptus. Of these, Mycosphaerella aurantia, M. heimii, M. lateralis, M. scytalidii, Pseudocercospora norchiensis, Teratosphaeria ohnowa and T. pluritubularis are newly recorded in Uruguay. This is also the first report of M. aurantia occurring outside of Australia, and the first record of P. norchiensis and T. pluritubularis in South America. New hosts were identified for Kirramyces gauchensis, M. aurantia, M. marksii, M. lateralis, M. scytalidii, P. norchiensis, T. molleriana, T. ohnowa and T. pluritubularis. Interestingly K. gauchensis, which has been known only as a stem pathogen, was isolated from leaf spots on E. maidenii and E. tereticornis. The large number of Mycosphaerellaceae and Teratosphaeriaceae occurring in Uruguay is disturbing and raises concerns regarding the introduction of new pathogens that could threaten not only Eucalyptus plantations but also native forests.     

Properties of reaction zones associated with decay from pruning wounds in plantation‐grown Eucalyptus nitens

Summary Decay columns resulting from naturally infected pruning wounds in 5‐ to 8‐year‐old plantation‐grown Eucalyptus nitens in Tasmania are interfaced by a reaction zone in the sapwood. The reaction zone is blue‐purple in colour and occasionally associated with a white zone at the reaction zone/healthy sapwood interface. A log incubation experiment has shown that the reaction zone is particularly durable against decay. The reaction zone is significantly drier than healthy sapwood, with lower levels of potassium, and a lower pH than both sapwood and heartwood. The increased total phenols levels and abundant tyloses in the reaction zone may be particularly important in defence.     

Where to shoot your pilodyn: within tree variation in basic density in plantation Eucalyptus globulus and E. nitens in Tasmania

Longitudinal patterns of within tree variation for basic density were determined for plantation Eucalyptus globulus (ages 5 and 10 years) and E. nitens (ages 5, 10 and 15 years) growing in three geographic areas in Tasmania. Each tree was sampled by taking discs from a combination of percentage heights (0, 10, 20 ___ 70%) and fixed height samples (0.5 m, 0.7 m ___ 1.5 m). At each of the fixed heights, a single pilodyn reading was taken from each of 4 aspects. Weighted whole tree density was calculated from the percentage height samples and used for correlation and regression analysis with the fixed height samples. Both species showed an initial drop in density between the felling cut (zero height) and 0.5 m, followed by a linear increase in density between 10% and 70% of tree height. Slope of fitted regressions were parallel within species but differed significantly between the species (1.14 kg/m³ and 1.62 kg/m³ per 1% increase in height above 10% for E. globulus and E. nitens, respectively). Density at all fixed heights was highly correlated with whole tree values for E. globulus, but results were variable across sites for E. nitens. Both species were found to contain trees which produced aberrant pilodyn readings. For E. globulus, the optimal sampling height was 1.3 m above ground and the mean pilodyn reading was found to predict whole tree density with an accuracy of ±21 kg/m³. For E. nitens, optimal sampling height was 1.5 m above ground. However, pilodyn readings around the stem were not very repeatable and correlations with whole tree density were lower, resulting in the accuracy of prediction of whole tree density being ±26 kg/m³.     

Patterns of longitudinal and tangential maturation stresses in Eucalyptus nitens plantation trees

Context

Tree orientation is controlled by asymmetric mechanical stresses set during wood maturation. The magnitude of maturation stress differs between longitudinal and tangential directions, and between normal and tension woods.

Aims

We aimed at evaluating patterns of maturation stress on eucalypt plantation trees and their relation with growth, with a focus on tangential stress evaluation.

Methods

Released maturation strains along longitudinal and tangential directions were measured around the circumference of 29 Eucalyptus nitens trees, including both straight and leaning trees.

Results

Most trees produced asymmetric patterns of longitudinal maturation strain, but more than half of the maturation strain variability occurred between trees. Many trees produced high longitudinal tensile stress all around their circumference. High longitudinal tensile stress was not systematically associated with the presence of gelatinous layer. The average magnitude of released longitudinal maturation strain was found negatively correlated to the growth rate. A methodology is proposed to ensure reliable evaluation of released maturation strain in both longitudinal and tangential directions. Tangential strain evaluated with this method was lower than previously reported.

Conclusion

The stress was always tensile along the longitudinal direction and compressive along the tangential direction, and their respective magnitude was positively correlated. This correlation does not result from a Poisson effect but may be related to the mechanism of maturation stress generation.     

Defence responses in plantation‐grown Eucalyptus globulus and Eucalyptus nitens after artificial fungal inoculation

The formation of reaction and barrier zones was studied in the xylem of Eucalyptus globulus and Eucalyptus nitens tree stems after wounding and artificial inoculation with two white rot fungi. The study had two objectives: to describe host responses in Eucalyptus spp. by light microscopy and to determine whether they would differ in a fungal treatment (wounding and inoculation by one of two fungal isolates) when compared to a control treatment (wounding only). Eucalyptus globulus and E. nitens developed similar reaction and barrier zones. The E. globulus barrier zone was characterized by kino vein formation. In both hosts, the reaction zone was primarily influenced by content and distribution of living tracheids and parenchyma cells within the sapwood. By contrast, the anatomy of the barrier zone showed similarities to the basic xylem structure of each host, except for some cell types that were newly formed (sclereids, kino veins) or increased in number (parenchyma cells, tracheids). Other cell types were reduced in number or completely absent. Host response in terms of barrier zone width appeared to be greater in the fungal than control treatment. Both wood decay fungi appeared to induce a wider barrier zone in both species than that associated with non‐specific damage caused exclusively by wounding. However, the small number of replicates available for this study was possibly insufficient to provide statistical evidence for different barrier zone width between fungal and control treatments.     

Temporal variation of microfibril angle in Eucalyptus nitens grown in different irrigation regimes

In 1990, a 2-ha plantation of Eucalyptus nitens (Deane and Maiden) Maiden was established in southeastern Tasmania and subjected to different irrigation regimes. Point dendrometers were installed in March 1995 to monitor radial stem movement every 15 min over several growing seasons. In this study, data from two growing seasons (1996-1998) were considered. From these measurements, daily increments of stem radius were determined. At the end of the second growing season, we extracted 12-mm cores and measured microfibril angles (MFA) of the wood at high resolution. Microfibril angles were rescaled on a time axis and mapped to daily and distance-based elements. Among treatments, irrigated trees in particular formed higher MFA early in the growing season (September-November) and lower MFA later in the growing season. Trees subjected to cyclic droughts showed clear relationships between MFA and soil water deficits, with MFA increasing in response to water stress release. Increases in MFA were preceded by accelerations in daily increment of stem radius. Among treatments, trees subjected to severe drought had the smallest MFA and generally low fluctuations in MFA. Irrigated trees were susceptible to changes in climate, whereas growth of the trees in the other treatments was limited by water availability. Use of path-analysis showed that temperature had an effect on stem radius increment but not on MFA; wind speed was the only factor that influenced MFA directly. Microfibril angle was correlated with stem shrinking and expansion phases; growth period length and growth rates were positively related to MFA.     

Applying PROMOD spatially across Tasmania with sensitivity analysis to screen for prospective Eucalyptus globulus plantation sites

When screening areas as prospective plantation sites two criteria are of interest: the expected yield at that site and the uncertainty associated with this yield expectation. This paper describes a methodology to enable spatial estimates of uncertainty to be attached to predictions of tree growth in relation to variations in soil depth, nutrient status, and drainage. An environmental sensitivity analysis was applied using the growth model PROMOD to produce site productivity and suitability maps for Eucalyptus globulus (Labill.) on a 1000 m regular grid of Tasmania. Nine productivity surfaces were computed, one for each of three assumed soil-water holding capacities (for soil depths of 0.5, 1.0, and 1.5 m — the common classes in Tasmania), combined with three permutations of soil-nutrient rating (the expected rating and one class above and one below this value), and incorporating potential waterlogging estimates. The mean and coefficient of variation was calculated for each 1000 m grid cell in the nine subsequent productivity surfaces. A final plantation suitability grid was then mapped to show areas of the State with predicted high (>25 m³ ha⁻¹per year), moderate (15–25 m³ ha⁻¹ per year), and low productivity (<15 m³ ha⁻¹ per year), each with corresponding high variability (coefficient of variation (CV>30%)) and low variability classes (CV<30%). As no areas had both, high productivity and high variability, only five plantation suitability classes were mapped.Those areas indicated as high productivity/low variation sites have a high probability of being successful E. globulus plantations. Low productivity sites with either high or low variation are very unlikely to be favourable for this species. Moderate productivity sites with low variation are likely to be viable potential plantation sites with relatively low risk, particularly with nutrient amelioration. Moderate productivity sites with high variation might warrant further field investigation to determine if there are major environmental factors or combinations of these, such as soil depth (water holding capacity), nutrient status, or drainage that are actually going to be limiting reasonable growth at these sites.     

The effect of wide initial spacing on wood properties in plantation grown Eucalyptus pilularis

Eucalyptus pilularis planted at three initial stocking densities of 833, 1111 and 1,667 stems ha^?1 grown at either square or rectangular spacing was assessed for the effects of stocking and rectangularity on wood properties. Sample trees from each stocking and rectangularity combination were harvested at age 7 years and assessed for the commercially important wood properties of bow, as an indication of growth strain, shrinkage and basic density. Crown length ratio was used as an indicator of stand vigour and clear wood availability. Furthermore comment is made on the financial ramifications of wide inter-row spacing. Stocking and rectangularity significantly influenced bow but not shrinkage or basic density. Reducing within-row spacing to 2 m with a larger between-row-space of 6 m had minimal affect on wood properties. Reducing the number of rows, whilst still retaining a commercial stocking, reduces the establishment costs and increases the ease of mechanical harvesting without adversely affecting log value.     

Measured and predicted changes in tree and stand water use following high-intensity thinning of an 8-year-old Eucalyptus nitens plantation

We investigated changes in the pattern of water use of an 8-year-old Eucalyptus nitens (Deane and Maiden) Maiden plantation soon after thinning. Sap flow sensors using heat pulse technology were deployed across three stands thinned to a final density of 100, 250 or 600 trees ha-1 plus an unthinned control (1250 trees ha-1). Changes in the relationship between tree size and daily water use were measured for 4 to 7 months after thinning. Thinning had no effect on sapwood water content. The increase in tree water use as a result of thinning was driven largely by significant changes in the radial pattern of sap velocity through the sapwood. The use of a canopy fraction factor in the Penman-Monteith equation to account for discontinuous canopies showed promise as a simple and effective method of scaling the model to predict transpiration from thinned plantations.     

Effects of green pruning on growth and stem shape of Eucalyptus nitens (Deane and Maiden) Maiden

An experiment was established in two high quality Eucalyptus nitens Deane and Maiden (Maiden) plantations in Tasmania. At the start of the experiment the trees were three years old and the plantations were on the point of canopy closure. Selected trees were pruned to remove 0, 50% or 70% of the lower green crown length, and each was surrounded by eight unpruned trees. The 50% treatment had no impact on height or diameter increment in the two years following treatment, but removal of 70% of the lower crown length resulted in significant decreases in both height and diameter increment. There were no changes in the height of 50%-pruned trees relative to the height of surrounding unpruned trees (relative height), and it was concluded that dominance would not be affected by this treatment. The relative height of 70%-pruned trees was less at one site, and this treatment may result in loss of dominance. Stem taper was generally unaffected by either pruning treatment. Changes in stem form were restricted to trees in the 70% pruning treatment and were only transient. It was concluded that removal of 50% of the lower green crown length is an appropriate level of pruning for the species provided that growth rates are rapid and pruning is timed to coincide with canopy closure. Since dominance was unaffected by this level of pruning, thinning at the time of pruning is unnecessary. It may be possible to minimise the impact on growth of higher levels of pruning by thinning at the time of pruning.     

Teratosphaeria gauchensis associated with trunk,stem and foliar lesions of Eucalyptus globulus in Portugal

Teratosphaeria gauchensis and T. zuluensis both cause a stem canker of eucalypts that leads to serious damage in various parts of the world. Until recently, this disease was unknown in Portugal. Nevertheless, severe damage to Eucalyptus globulus has been observed in Portugal since 2006 when symptoms appeared as necrotic spots on young green stems and leaves, twig lesions, and dark oval‐shaped lesions on stems and trunks. The isolates from affected E. globulus tree plantations were identified using sequence data of the ITS1‐5.8S‐ITS2 and EF‐1α clusters, together with morphological characteristics. Based on these results, the causal organism was identified as T. gauchensis, which represents the first report of this pathogen from Portugal.     

Impact of number of stems per stool on mechanical harvesting of a Eucalyptus globulus coppiced plantation in south-west Western Australia

Coppice regeneration of eucalypt plantations is increasingly being used in Australia to reduce re-establishment costs. However, little is known about the impact of early coppice reduction regimes on harvester performance during clearfelling. The trial compared the productivity, time consumption, cost and fuel use of a single-grip harvester (Hyundai 210LC-9 base and SP 591LX harvesting head) clearfelling a 10.5-year-old, second-rotation coppiced Eucalyptus globulus stand in south-west Western Australia for chip logs. Coppice stems had been reduced to one stem or two stems per stool or left untreated. Time and piece counts were used to determine harvester productivity. Harvester cycle and elemental times and the number of logs and harvester head passes per stem were obtained from video recordings. Harvester fuel use was determined by refilling the fuel tank to the same point each day. Stem size was the major factor influencing harvester productivity (20.8 m3 per productive machine hour without delays [PMH₀], 11.8 m³ PMH₀^?1 and 8.6 m³ PMH₀^?1 in the single-stem (mean stem volume [MSV] 0.21 m³), two-stem (MSV 0.09 m³) and untreated trial areas (MSV 0.06 m³), respectively. Estimated harvester cost (AU$ m^–3) was considerably greater for the two-stem and untreated trial areas, which reflected the lower harvester productivity in these areas. Processing time represented over 60% of the total cycle time for all trial areas. Coppice characteristics resulted in significantly different moving/positioning times between trial areas. However, this difference had no impact on cycle times. Number of logs per stem was a significant variable in cycle and processing time regressions for all trial areas and felling time for the single-stem trial area. Number of harvester head passes was a significant variable in cycle and processing time regressions for the single-stem trial area and processing times for the two-stem trial area, although its effect was less than that of the number of logs per stem. Fuel consumption (L PMH₀^?1) was relatively constant between the trial areas, hence harvester energy intensity (L m^?3) reflected the harvester productivity in each trial area.     

Long-term realised and projected growth impacts caused by autumn gum moth defoliation of 2-year-old Eucalyptus nitens plantation trees in Tasmania,Australia

Insect damage to production forests has the potential to reduce financial returns by retarding tree growth and causing mortality, however, long-term realised quantification of these losses is rare. In order to help elucidate economic damage thresholds for making spray decisions we capitalised on a natural outbreak of autumn gum moth, Mnesampela privata, in a 2-year-old Eucalyptus nitens plantation. Following the partial chemical control of this insect outbreak we measured the tree growth variables diameter at breast height over bark and height of five differing tree defoliation classes for 75 months following tree damage. At the end of this period a threshold model was fitted to describe the relationship between tree defoliation and realised tree wood volumes. The model revealed that realised stand wood volume was not significantly affected up until defoliation exceeded 60% and then declined sharply after this defoliation level was reached. Further support for this defoliation threshold was evident from multiple comparisons among defoliation classes that showed 50% defoliated trees did not have significantly different wood volume compared to more lightly defoliated trees, but did have significantly greater wood volume compared to trees that were 72% or more defoliated. To determine if the realised differences in wood volume resulted in differences in yield over a plantation rotation the E. nitens growth model NITGRO was used to on-grow trees to age 15 years for a ‘best case’ (type 1 growth response, constant growth rates from last inventory until harvest) and ‘worst case’ (type 2 growth response, divergent growth rates from last inventory until harvest) scenario. The threshold model was then fitted to the outcomes of both scenarios and the economic consequences of defoliation were clearly dependent on the growth function assumed.     

Botryosphaeriaceae associated with Eucalyptus canker diseases in Colombia

The identities of Botryosphaeriaceae causing cankers on Eucalyptus in Colombia were investigated using morphological and DNA sequence comparisons. The pathogenicity of the species was also assessed on 42 Eucalyptus grandis clones planted at four different sites. Two species of the Botryosphaeriaceae were found to occur on E. grandis in Colombia. Neofusicoccum ribis was the more common species, and also the most pathogenic. Botryosphaeria dothidea was found only in one zone of Colombia, and was also less pathogenic than N. ribis. These two species could be distinguished easily based on DNA sequences of the ITS1/ITS2 rDNA region and EF1‐α, in addition to conidial sizes. Significant differences in resistance of clones to these pathogens were also evident from the various trials.     

桉树人工林冰雪灾害恢复的调查

通过冰雪灾害后的冻害调查和多次恢复调查,探讨了桉树冻害评价指标与恢复能力的相关性及其对桉树耐寒性评价的适用性,从灾后恢复水平评价了多种桉树和无性系的耐寒性,总结了不同种类和无性系在不同纬度、不同海拔、不同年龄和不同恢复措施下的恢复能力和恢复特点。     

Effect of season and different fungi on phenolics in response to xylem wounding and inoculation in Eucalyptus nitens

Pot‐grown and plantation‐grown Eucalyptus nitens trees (approximately 2 and 3 years old, respect‐ively) were experimentally wounded and inoculated with different fungi and in different seasons. Decay lesion development and defence zones were assessed. Two zones were described, a narrow brown decay interface (interface reaction zone, IRZ) and a diffuse zone beyond this being either pale brown or purple (reaction zone, RZ). The total phenol levels in the reaction zone were determined. Selected phenolics (pedunculagin, tellimagrandin 1, tetragalloylglucose, pentagalloylglucose and catechin) were quantified by liquid chromatography–mass spectrometry (LC–MS). A range of fungi (mainly decay‐causing) were used to inoculate wounds and the results indicated that more extensive decay lesions were generally associated with greater production of soluble phenols in response. Sterile inoculations and weakly aggressive fungi were associated with no or little xylem discoloration, whereas aggressive fungi elicited more discoloration and phenolic accumulation in advance of infection. This indicates that phenol accumulation is not a generalized response to wounding, but a variable response due to the interaction between microorganisms and sapwood. In plantation‐grown trees examined 6 months after wounding, purple reaction zones were commonly associated with large decay lesions. Seasonal differences in decay column area caused by Ganoderma applanatum were not significant 1 month after wounding and inoculation.     

Chloride content and biomass partitioning in Eucalyptus hybrids grown on saline sites

Eucalyptus camaldulensis × globulus and E. camaldulensis × grandis hybrids have been developed to combine the salt–waterlogging tolerance and high-quality wood fibre of their respective parents. The aim is to develop trees that will grow in relatively dry and/or saline environments and provide commercial wood products. Previous studies indicate that the hybrids exhibit faster growth than either of their pure species parents, and that there are significant differences in growth rates between them. We undertook a comparative study of the partitioning of above-ground biomass (AGB) to examine biomass and chloride (Cl) allocation of trees growing on two saline-irrigated sites in south-eastern Australia. Eucalyptus camaldulensis × globulus had a higher proportion of AGB in leaves (20–29% cf. 15–16%), and lower proportion in live branches (3–10% cf. 6–14%) than E. camaldulensis × grandis. The concentration of Cl was highest in the stembark (4.2–9.6 g kg⁻¹) and lowest in the stemwood (0.6–2.0 g kg⁻¹), suggesting that trees can export Cl through bark shedding. Total Cl content was strongly related to volume under bark (R² = 0.99), and differences in partitioning of Cl into tree components differed between the hybrids in the same way as AGB. Preferential partitioning of Cl to live branches rather than foliage in E. camaldulensis × grandis suggests that this hybrid may be compartmentalising Cl to reduce the risk of Cl toxicity in the leaves.