Search

South Africa has 1.2 million hectares of plantations developed progressively through the 20th century. These occur from 23° to 34°S, from near sea level to 2 000 m above sea level and in both Mediterranean winter rainfall and summer subtropical rainfall climates. Plantations supply pulp mills, sawmills, treated pole and mining timber production, and wattle tannin production. The diversity of sites and markets requires planting of a range of taxa of pine, eucalypt and wattle. A survey of planted area by taxa in South African forest plantations is reported and compared to statistics available from national annual reporting on the commercial timber resources in the country. The survey found a similar number of taxa are currently planted (15) as in the 1950s but only 6 of the earlier options remain in use. Changes have occurred in the last 30 years, with 40% of planted area in 2019 using options not available before 1990. From the 1990s, Eucalyptus grandis has been extensively replaced by eucalypt hybrids and E. dunnii and Pinus elliottii × P. caribaea var. hondurensis has become an important pine planting option. Over the past decade, E. nitens replacement with other existing frost tolerant eucalypt planting options has occurred, use of P. radiata has reduced and P. patula has been replaced on a significant scale with P. patula hybrids. Many of these changes have been to mitigate the impact of new pests and pathogens and, on lower productivity sites, periodic severe droughts. However, the new planting options also provide increased yields and have wood properties acceptable to the intended markets. Meeting all three criteria is likely to remain a requirement for successful introduction of future new planting options. The survey indicates a need to revise current national reporting requirements to better reflect use of species and hybrids in South African plantations. [ABSTRACT FROM AUTHOR]

Grey mould, caused by the fungus Botrytis cinerea, is one of the diseases that occur in seedlings of Eucalyptus dunnii. The control of this disease is carried out mainly with chemical fungicides, but such use should be restricted to cases of high severity. An interesting alternative is the biocontrol using endophytic microorganisms. We assessed the antagonistic potential of endophytic yeasts from coffee beans against B. cinerea in vitro and their potential for biocontrol of grey mould in detached leaves and three-month-old seedlings of E. dunnii. Ten strains significantly inhibited the growth of B. cinerea in vitro (59.9–86.9%), and Wickerhamomyces anomalus showed the highest inhibition of the pathogen. In the in vivo assays, W. anomalus remained viable for 10 days after spraying on leaves and reduced the severity of the grey mould in E. dunnii detached leaves and seedlings. The results were statistically similar to those obtained with chemical fungicide when sprayed weekly. This is the first report of the effectiveness of endophytic W. anomalus as a suppressor of the development of grey mould in E. dunnii. [ABSTRACT FROM AUTHOR]

In the present work, Eucalyptus nitens was thermally modified in an open (atmospheric pressure) and a closed (under pressure) reactor system. The effect of the changes of the chemical composition on the mechanical properties was investigated. Hemicelluloses, cellulose, lignin, extractives, acetic acid, formic acid, total phenols and the cellulose degree of polymerization (DP) as well as modulus of elasticity (MOE) and modulus of rupture (MOR) were measured for each modification. The results indicated that the closed system modification, particularly at high pressure, presented stronger variations on the chemical structure of the modified wood than the modifications in the open system. In both modifications, MOR showed a better correlation with the chemical changes than the MOE, especially xylose, cellulose DP, lignin and total phenols. These correlations suggest a tendency of a more brittle wood in the closed system modification at high pressure than in the modifications in the open system. Results can be used as a reference for future applications of thermally modified E. nitens wood. [ABSTRACT FROM AUTHOR]

The purpose of this study was evaluating polysulfides (PS) as additives in kraft cooking of wood mixtures eucalypt (E) and pine chips (P) wood mixtures, namely: 50E/50P, 70E/30P, and 90E/10P. Bleaching (O(D/A)(EP)D) and refining of pulps were also investigated. The PS addition (1.5 or 3.0%) to the kraft cooking preserved the hemicelluloses resulting increased pulp yield and reduced H-factor. The oxygen delignification was more efficient for chip mixtures containing higher proportion of pine chips, but was not largely affected by the addition of PS. The bleach chemical consumption was not significantly influenced by PS dosage or by the wood chip mixture. The burst and tear indexes were improved by increasing the proportion of pine chips to the mixture, but an opposite effect was observed for refinability, tensile index, and opacity. The kraft-PS pulps showed increased refinability, tensile, and burst strengths in relation the standard pulps, but lower opacities. [ABSTRACT FROM AUTHOR]

The history of the treatment of tuberculosis in Australia has largely been focused on the development of medical treatments, the architectural features of custom-built sanatoria and the human impact of the disease in the nineteenth and early twentieth centuries. These discussions often mention contemporary debates amongst medical men and the laity regarding the best treatment, but the influence of medical climatology in deciding where medical facilities should be placed is often overlooked. The first sanatorium in the Colony of Victoria had two branches: Echuca and Mount Macedon. These two locations differ in terms of altitude, the surrounding forest and meteorological variation. Yet, both sites were considered suitable at the time for the location of a sanatorium, possibly due to the health-promoting and aesthetic aspects of nearby eucalypt forests. This article explores why they may at first modernly appear to be substantially different locations, but contemporary medical climatology emphasised their similarities. [ABSTRACT FROM AUTHOR]

In South Africa, commercial eucalypt stands may be regenerated through the stepwise reduction of coppice shoots following felling. The development of secondary coppice regrowth following these reduction operations results in competition with the remaining stems, possibly resulting in a reduction in growth. Currently, secondary coppice regrowth is controlled manually, or through spraying with glyphosate at 0.6% when ca. 0.75 m in height. No research has been conducted to determine whether alternative rates and/or timing of application are possible or cost-effective. In 2006 a trial was implemented in Zululand, South Africa on a recently coppiced stand ofEucalyptus grandis×Eucalyptus urophyllaso as to optimise rates of glyphosate application (0.6%, 1.2% and 1.8%) for the control of secondary coppice regrowth at various heights (0.5, 1.0 and 1.5 m). Tree and secondary coppice regrowth variates were measured annually until rotation-end (9 years, 3 months). The volume of herbicide used, the number of occasions each treatment was sprayed and associated costs were combined to provide an indication of the most cost-effective treatment. Although there were no significant differences in final coppice yield for the various rates of glyphosate and timing of application (as assessed by the size of the secondary coppice regrowth) tested, treatment efficacy in terms of treating secondary coppice regrowth increased with an increase in the rate of glypho- sate applied (0% < 0.6% < 1.2% < 1.8%), especially when treated at either 1.0 or 1.5 m in height. The use of glypho- sate, irrespective of rate and/or timing of application (as assessed by secondary coppice regrowth height), proved to be more cost-effective compared with manual control or the spraying of the secondary coppice regrowth at 0.75 m height with 0.6% glyphosate. The most cost-effective treatment was 1.2% glyphosate applied when the secondary coppice regrowth was 1.5 m. If reduced herbicide use is a major criterion within a company portfolio, then the secondary coppice regrowth can be manually removed when 1.5 m. [ABSTRACT FROM PUBLISHER]

Eucalyptus is widely cultivated in homogeneous monocultures throughout the world alongside plants of the same age. Furthermore, the productivity of forest stands is highly dependent on how solar radiation is intercepted and used. Meanwhile, it is possible to consider cultivating trees of different ages in the same area, and thus under different regimes of available solar radiation, creating a sequence of plantings and harvestings and to develop Eucalyptus-based agroforestry systems. We have examined biomass accumulation ofEucalyptus camaldulensisalong a shade gradient. Eucalyptus trees presented power-law responses to increasing irradiance for biomass, indicating it has low plasticity and is unable to maintain growth under lower irradiance levels. Biomass partitioning showed no dependence on available irradiation. Leaf density presented very little increase toward sunnier places meaning that an increment in Eucalyptus biomass would be mostly due to its increase in size and thus higher radiation interception. Careful management of shade will be a key consideration for the integration of Eucalyptus into agroforestry. With knowledge of the growth habits of different species, we will have the potential to propose more perennial ways in which to manage land and reduce anthropogenic disturbances by avoiding clear-cuts of areas that removes all plant structures. [ABSTRACT FROM AUTHOR]

The effect of pulp pretreatment with hot acid hydrolysis on high consistency ozone bleaching was evaluated. An experimental plan was set up involving the full optimization of the A-stage and its application in Elemental Chlorine Free–ECF–[A/(aZe)DP and A(aZe)DP] and Total Chlorine Free–TCF–[A/(aZe)(EP)P and A(aZe)(EP)P] sequences for eucalypt kraft pulp bleaching. The A-stage removed a significant amount of lignin and HexA from the pulp, and the subsequent Z-stage remained efficient after completion of the A-stage. The chemical savings caused by the A-stage were significant (∼7 kg ClO2/adt). The optimum conditions for the A-stage were pH 3.0, 90°C for 120 min, and 10% consistency. The strength properties of pulps bleached with the (aZe)DP (reference) and A/(aZe)DP ECF sequences were similar, but the TCF sequence A/(aZe)(EP)P delivered slightly lower strength properties than the ECF sequences. Fiber peeling studies indicated that the HexA present in the kraft pulp is not concentrated on the fiber surface, as previously thought. [ABSTRACT FROM AUTHOR]

Previous descriptions of multisite and multispecies near infra-red (NIR) spectroscopic calibrations for predicting cellulose content (CC) and Kraft pulp yield (KPY) in eucalypt woodmeal demonstrated that large, single calibrations provide precise predictions for a wide range of sites and species. These have since been used in a range of published studies. Their value lies in low-cost, fast analytical throughput and small required sample size. In particular, they allow precise values of KPY to be obtained from small wood samples obtained non-destructively. This study reports the ongoing performance of these calibrations with respect to laboratory chemical values, as well as describing a wood density calibration. Cellulose content was measured in an additional 550 samples taken from over 14 different data sets. The standard error of prediction (SEP) of CC was 0.35% with an average bias of only 0.28%. Adding these samples to the existing calibration gave a sample set of 1 800 samples, producing a calibration with a crossvalidation r2 of 0.87 and standard error of 0.78%. The existing KPY calibration was assessed against an additional 527 samples generating a standard error of prediction of 1.9% and a bias of -1.8%. Adding the samples to the calibration gave a sample set of 1 360 samples producing a calibration with a crossvalidation r2 of 0.87 and standard error of 1.29%. The correlation between NIR-predicted CC and NIR predicted KPY was 85%. A wood density calibration was developed using data generated from wood chips. A total of 1 138 samples were separated randomly into calibration and test sets, representing between 19% and 38% of the sample set. The SEP values were between 34 and 40 kg m−3 and explained between 72% and 84% of the variance. The final calibration including all samples had a crossvalidation r2 of 0.82 and standard error of 29.5 kg m−3. [ABSTRACT FROM AUTHOR]

Corymbia hybrids are becoming significant plantation varieties in subtropical and tropical Australian plantation forestry. Although primarily developed for disease resistance and amenability to clonal propagation, they have also proven to have good growth rates and site plasticity. Here we examined the susceptibility of pure Corymbia species and hybrids to pest attack. Three trial sites containing C. citriodora subsp. variegata, C. torelliana, and the hybrids C. torelliana × C. citriodora subsp. variegata, C. torelliana × C. citriodora subsp. citriodora and C. torelliana × C. henryi were assessed for pest identity, incidence and severity. Pests caused about three-quarters of the visible crown damage to trees in these trials. At the site that had the most arthropod damage, hybrid trees had higher damage scores and higher growth scores (height, diameter at breast height over bark, and volume) than pure species. Site was more important than taxon in explaining damage scores, and taxa performed differently for most traits between sites. Tree growth was negatively correlated with general crown damage, while arthropod damage alone showed no significant relationship with growth. Our results highlight the importance of establishing taxa trials across a range of sites when selecting for pest resistance. [ABSTRACT FROM AUTHOR]

The prognosis and utility under climate change are presented for two old-growth, temperate forests in Australia, from ecological and carbon accounting perspectives. The tall open-forests (TOFs) of south-western Australia (SWA) are within Australia's global biodiversity hotspot. The forest management and timber usage from the carbon-dense old-growth TOFs of Tasmania (TAS) have a high carbon efflux, rendering it a carbon hotspot. Under climate change the warmer, dryer climate in both areas will decrease carbon stocks directly; and indirectly through changes towards dryer forest types and through positive feedback. Near 2100, climate change will decrease soil organic carbon (SOC) significantly, e.g. by ∼30% for SWA and at least 2% for TAS. The emissions from the next 20 years of logging old-growth TOF in TAS, and conversion to harvesting cycles, will conservatively reach 66(±33) Mt-CO2-equivalents in the long-term - bolstering greenhouse gas emissions. Similar emissions will arise from rainforest SOC in TAS due to climate change. Careful management of old-growth TOFs in these two hotspots, to help reduce carbon emissions and change in biodiversity, entails adopting approaches to forest, wood product and fire management which conserve old-growth characteristics in forest stands. Plantation forestry on long-cleared land and well-targeted prescribed burning supplement effective carbon management. Abbreviations: C, carbon; CBS, clearfell, burn and sow; CO2-e, CO2 equivalents; CWD, coarse woody debris; DOC, dissolved organic carbon; GHG, greenhouse gas; Mt, megatonnes; SOC, soil organic carbon; SWA, south-western Australia; SWAFR, Southwest Australian Floristic Region; TAS, Tasmania; TOF, tall open-forest; t-C ha-1 yr-1, tonnes of carbon per hectare per year [ABSTRACT FROM AUTHOR]

The spotted gum species complex represents a group of four eucalypt hardwood taxa that have a native range that spans the east coast of Australia, with a morphological cline from Victoria to northern Queensland. Of this group, Corymbia citriodora subsp. variegata (CCV) is widespread in south-eastern Queensland and northern New South Wales. It is currently the most commonly harvested native hardwood in Queensland. However, little basic knowledge of the reproductive biology of the species is available to inform genetic improvement and resource management programmes. Here we take an integrative approach, using both field and molecular data, to identify ecological factors important to mating patterns in native populations of CCV. Field observation of pollinator visitation and flowering phenology of 20 trees showed that foraging behaviour of pollinator guilds varies depending on flowering phenology and canopy structure. A positive effect of tree mean flowering effort was found on insect visitation, while bat visitation was predicted by tree height and by the number of trees simultaneously bearing flowers. Moreover, introduced honeybees were observed frequently, performing 73% of detected flower visits. Conversely, nectar-feeding birds and mammals were observed sporadically with lorikeets and honeyeaters each contributing to 11% of visits. Fruit bats, represented solely by the grey-headed flying fox, performed less than 2% of visits. Genotyping at six microsatellite markers in 301 seeds from 17 families sampled from four of Queensland's native forests showed that CCV displays a mixed-mating system that is mostly outcrossing (tm = 0.899 ± 0.021). Preferential effective pollination from near-neighbours was detected by means of maximum-likelihood paternity analysis with up to 16% of reproduction events resulting from selfing. Forty to 48% of fertilising pollen was also carried from longer distance (>60 m). Marked differences in foraging behaviour and visitation frequency between observed pollinator guilds suggests that the observed dichotomy of effective pollen movement in spotted gums may be due to frequent visit from introduced honeybees favouring geitonogamy and sporadic visits from honeyeaters and fruit bats resulting in potential long-distance pollinations. [ABSTRACT FROM AUTHOR]

Achieving a well-stocked stand at time of planting is important to compartment productivity and yield in clonal eucalypt stands for pulpwood production. The window period in which individuals that replace those that died after initial planting (blanks) still contribute meaningfully to final yield is set by the competition dynamics between individuals within the stand. The longer the period between planting and blanking, the greater the advantage achieved by original plantings in dominating site resources (light, water and nutrients) and suppressing blanks. A blanking trial was established to determine growth differences of blanked and original individuals and productivity per unit area. Factorial combinations of blanking period after planting, mortality pattern and extent of mortality were tested. Analysis of measurements at four years showed that the period before blanking is the only factor that significantly accounts for the variation in plot volume between treatments, although the percent mortality and pattern of mortality by percent mortality together also have influence on plot volume. Late blanking results in a higher proportion of suppressed trees that contribute little to total volume. Asymmetric competition is more pronounced where late blanking is carried out and where mortality is spread, rather than clumped. [ABSTRACT FROM AUTHOR]

Eucalyptus globulus is the main eucalypt species grown in Australian plantations. The focus on seedling deployment systems, coupled with exploitation of large, open-pollinated base populations for breeding purposes over the last two decades, has required a detailed understanding of the reproductive biology of this species. We review our research on the reproductive biology of E. globulus, with a focus on its breeding system and advances made in seed production systems. While most improved seed is still obtained from open-pollinated seedling or grafted seed orchards, the development of the one-stop/single-visit pollination procedure has revolutionised the breeding and deployment of this species. The reduced costs of controlled pollination has meant full pedigree-control can now be maintained in large advanced-generation breeding populations and E. globulus is one of the few eucalypt species where large-scale production of manually pollinated seed for family forestry is being undertaken. [ABSTRACT FROM AUTHOR]

Increasingly stringent effluent quality limits for bleached kraft pulp mills pose a great challenge to mill wastewater system managers since these limits can require levels of chemical oxygen demand (COD) removal efficiency rarely reported for biological treatment of these types of effluents. The present study was therefore undertaken to better understand the nature of recalcitrant COD in bleached kraft pulp effluents that persists through the biological treatment system. Bleaching effluents from a Brazilian eucalypt bleached kraft pulp mill were collected and treated in a bench-scale sequencing batch reactor. Organic matter in raw and treated effluents was characterized before and after separation into low and high molecular mass fractions. Biological treatment removed 71% of the COD, with 83% removal of the low molecular mass COD but only 36% removal of the high molecular mass COD. Microorganisms capable of degrading the recalcitrant COD were isolated from enrichment cultures of the original activated sludge fed on fractions of the bleaching effluent that presented low biodegradabilities. Use of a microbial consortium composed of ten of these isolates to treat the biologically treated effluent removed a further 12% of the effluent COD, all from the high molecular mass fraction. Results of this research indicate that microorganisms with potential for degrading recalcitrant COD are present in activated sludge, but that these are not metabolically active during normal activated sludge treatment of mill effluents. The use of biological selectors in the treatment system to promote growth of such microorganisms may enhance removal of recalcitrant organic matter. [ABSTRACT FROM AUTHOR]

With high quality petroleum running out in the next 50 years, the world governments and petrochemical industry alike are looking at biomass as a substitute refinery feedstock for liquid fuels and other bulk chemicals. New large plantations are being established in many countries, mostly in the tropics, but also in China, North America, Northern Europe, and in Russia. These industrial plantations will impact the global carbon, nitrogen, phosphorus, and water cycles in complex ways. The purpose of this paper is to use thermodynamics to quantify a few of the many global problems created by industrial forestry and agriculture. It is assumed that a typical tree biomass-for-energy plantation is combined with an efficient local pelleting facility to produce wood pellets for overseas export. The highest biomass-to-energy conversion efficiency is afforded by an efficient electrical power plant, followed by a combination of the FISCHER-TROPSCH diesel fuel burned in a 35%-efficient car, plus electricity. Wood pellet conversion to ethanol fuel is always the worst option. It is then shown that neither a prolific acacia stand in Indonesia nor an adjacent eucalypt stand is “sustainable.” The acacia stand can be made “sustainable” in a limited sense if the cumulative free energy consumption in wood drying and chipping is cut by a factor of two by increased reliance on sun-drying of raw wood. The average industrial sugarcane-for-ethanol plantation in Brazil could be “sustainable” if the cane ethanol powered a 60%-efficient fuel cell that, we show, does not exist. With some differences (ethanol distillation vs. pellet production), this sugarcane plantation performs very similarly to the acacia plantation, and is unsustainable in conjunction with efficient internal combustion engines. [ABSTRACT FROM AUTHOR]

Soil water repellency can enhance overland flow and erosion and may be altered by fire. The Christmas 2001 bushfires near Sydney allowed investigation of the relationship between fire severity, water repellency and hydrogeomorphological changes. For two sub-catchments with differences in fire severities in Nattai National Park, south-west of Sydney, this paper considers: (1) the links between fire severity based on SPOT image analysis and ground observation of fire severity and repellency; (2) the textural and organic/minerogenic characteristics of eroded sediment; and (3) erodibility, erosion and deposition of soils in both catchments. Ground surveys show that image analysis reflects well the degree of vegetation consumption by fire, but cannot adequately predict the degree of ground litter consumption, associated soil heating and repellency effects. Fire had varying effects on repellency, leaving it unchanged, destroying it or enhancing it, depending on the soil temperature reached. The main post-fire hydrogeomorphological changes have been widespread erosion and colluvial and alluvial deposition of topsoil in foot-slope locations and river systems, but only localised redistribution of the highly erodible, repellent sandy subsurface layer. The fire did not trigger major geomorphological change in the study area, but fires probably cause important topsoil and nutrient depletion and may also affect water quality. [ABSTRACT FROM AUTHOR]

Grassroots community organisations offer simple ways of maintaining natural heritage values. Given the degradation of landscapes supporting fauna in many parts of the world, such organisations promise direct benefits for local communities and ecological biodiversity. Also, global warming, resulting in part from the removal of forest, will abate with the restoration of trees. The Bend of Islands (Victoria, Australia) boasts two organisations dedicated to the communal conservation of a landscape of remnant box-ironbark (eucalypt) forest. This woodland heritage is managed by residents to preserve its ecological values.The Round the Bend Conservation Co-operative (RBCC) is a land settlement co-operative. Members are committed to maintaining the local bushland in as natural a state as possible using minimal-impact environmental practices. The Bend of Islands Conservation Association (BICA) was established several years after the co-operative, but with the same environmental purpose. It covers a broader area, incorporating over 130 private land titles. This article describes the history and practices of RBCC and BICA and indicates their potential as models for the development of conservation principles and practices by other communities in similar landscapes. [ABSTRACT FROM AUTHOR]