Eucalyptus Globulus Plantations Research Articles

Potential of Pinus radiata, Eucalyptus globulus and Acacia dealbata for the long-term phytostabilization of copper mine tailings

Many contaminated tailings throughout the world cause environmental and human-health related problems due to air and water drift. Tailing phytostabilization is a promising solution, but only certain plant species may tolerate and grow in these contaminated areas. We analyzed the chemical properties of a vegetated and unvegetated area in a tailing site in Central Chile. In addition, in the vegetated area we analyzed the metals content of roots, stems, and foliage in 41-years old plantations of Pinus radiata, Acacia dealbata, and Eucalyptus globulus (the only three species that survived from a total of 34 species planted), and determined height (H), and diameter at breast height (DBH). The results indicated that, except for pH, Se, Pb, and organic matter, all components (nutrients and metals) were two- to three- fold lower in the vegetated tailing compared to that of the unvegetated tailing. The analysis of plant tissues indicated that Cu was higher in the roots of P. radiata (2,073 mg kg−1) and lower in the stems of the same species (4.1 mg kg−1). However, the ability to take up and transport Cu to the shoots was higher in A. dealbata and lower in P. radiata (bioaccumulation factor of 0.19 and 0.06, respectively).

Effect of Eucalyptus globulus Plantations on Soil Physicochemical Properties in the Upper Blue Nile, Ethiopia

In recent years, there has been a substantial conversion of croplands and grasslands to short rotation Eucalyptus globulus plantations in the northern highlands of Ethiopia. This has raised concerns among researchers, policymakers, and environmentalists regarding potential adverse effects on soil fertility. To address these concerns, a study was conducted to evaluate the impact of Eucalyptus globulus plantations on selected soil physicochemical properties in the region. The study involved four land-use types, comprising two age groups of Eucalyptus globulus plantations (4-year-old and 9-year-old), as well as areas designated for grasslands and croplands. Soil sampling was carried out in 10 m × 10 m subplots within each experimental plot, and standard methods were employed for soil analysis. The soil laboratory results were statistically analyzed using Two-way ANOVA and Pearson’s correlation coefficients in R software version 4.1.0. The findings revealed significant variations (p<0.05) in soil bulk density, soil organic carbon, and soil pH between the 4-year-old and 9-year-old Eucalyptus globulus plantations and the grasslands. A notable difference (p<0.05) in exchangeable acidity was observed between the 4-year-old and 9-year-old E. globulus plantations, with the latter exhibiting the highest mean exchangeable acidity (6.20 ± 0.76). However, no significant differences (p<0.05) were observed between the Eucalyptus plantations and the grasslands in available phosphorus (Av.P), exchangeable calcium (Ca2+), sodium (Na+), and magnesium (Mg2+) concentrations, as well as cation exchange capacity (CEC). The study results has, therefore, implied that Eucalyptus globulus plantations induced changes in specific soil properties with varying stand ages in the study area. Nonetheless, it was emphasized that further long-term research is necessary to comprehend the effects of these plantations on soil properties.

Physiological and hormonal responses of drought‐stressed Eucalyptus seedlings infected with Neofusicoccum kwambonambiense

AbstractThe contribution of Eucalyptus globulus plantations to timber production for pulp, paper and energy production may be hampered by climate change. It is expected that Eucalyptus productivity may be affected through drought stress and changes to both pathogen distribution/pathogenicity and host–pathogen interactions. The impact of the fungal pathogen Neofusicoccum kwambonambiense on E. globulus, causing cankers and dieback, is well known but the impact of drought on disease development is still understudied. Our aim was to study the effect of drought on N. kwambonambiense infection by inoculating E. globulus plants under well‐watered conditions or with water limitation. Non‐infected plants for both water regimes were also analysed. Morphophysiological, biochemical and hormonal parameters were assessed 65 days post‐inoculation. Inoculation under conditions of water stress decreased water potential and photosynthetic efficiency and increased abscisic acid, jasmonic acid and lipid peroxidation. Water‐stressed infected plants also showed higher fungal colonization and external lesion length in comparison with well‐watered inoculated plants. Our results indicate that drought increased E. globulus predisposition to N. kwambonambiense infection and may also have promoted a change in the lifestyle of the fungus. Identifying host–pathogen interaction responses under different stress conditions is necessary to provide knowledge for decision‐making in the management of forest systems in general and of Eucalyptus production in particular.

Exploring reproductive biology in Eucalyptus globulus clones under distinct climatic conditions

AbstractDespite the great economic benefits, one of the major threats of introducing species into exotic ranges is their ability to regenerate and spread to novel environments. For example, Eucalyptus globulus plantations have been established in many parts of the world, using seedlings or clonal material, the latter often from advanced generation tree improvement programs. However, major concerns exist about this species’ ability to invade non-native areas. Therefore, it is necessary to study whether breeding programs affect this species’ reproductive biology to assess the risk of invasiveness of these improved trees. In this sense, this work compared the E. globulus phenological behaviour and reproductive structures production of three clonal and one seedling-based stand across two distinct climatic zones (mesic and xeric) in Portugal. Through binocular observation, four different stands (seedlings descending from open-pollinated crosses and three clonal-stands) were monitored every three weeks for different reproductive phenological stages, namely the presence of flowers and capsules. Clonal stands presented a shorter flowering season, less abundant reproductive structures, and higher phenological variability across sites than seedling-based stands. Phenological patterns and fructification abundance also varied between the three clonal stands. These results suggest that clones with decreased reproductive ability can be chosen during the breeding process, lowering the dispersal risk while enhancing productivity. Thus, understanding the phenological behaviour of E. globulus is critical to more sustainable agroforestry by reducing the spread risks.

Impact of flail chain characteristics on productivity, costs, bark content and fuel use when processing short-rotation Eucalyptus globulus trees to produce woodchips

ABSTRACT Infield chipping harvest systems are widely used in Australia and overseas to produce woodchips for pulp production from short-rotation plantations because they can produce uniform woodchips at low cost with high productivity from small trees. Flail chains are used in these systems to remove leaves, small branches and bark prior to chipping because these components are undesirable in paper products. Flail chains wear during use and lose links, requiring chains to be replaced. A range of flail chains is available but the most recent studies comparing flail chain performance were conducted over 30 years ago. The aim of the present study was to address this knowledge gap by comparing the performance of five flail chain types currently in use in terms of their impact on flail productivity, fuel use, woodchip bark content, chain wear and chain replacement costs. The study was conducted on a Husky Precision 2300–4 flail operating in 13-year-old Eucalyptus globulus plantations in southwest Western Australia producing export woodchips. No significant differences were found between the studied flail chains in terms of woodchip bark content, flail productivity or flail fuel use. In all cases, bark content met company standards (<0.5%). Significant differences were found between the studied flail chains in terms of their wear, link losses and replacement costs. Chain replacement costs as a proportion of total flail costs were found to be considerably lower (<1% to 4%) than those reported in previous studies (>20%).

Phytochemical and Thin Layer Chromatographic Analysis of Chloroform and Methanol Extracts of Azadirachta indica and Eucalyptus globulus Leaves

The study focuses on phytochemical screening of Azadirachta indica and Eucalyptus globulus leaf extracts in chloroform and methanol solvents. The antibacterial compounds found in both leaf extracts of Azadirachta indica and Eucalyptus globulus plants were investigated using phytochemical studies. The extracts contained flavonoids, terpenoids, tannins, alkaloids, saponins, and phenolic chemicals, according to preliminary phytochemical screening. The solvent systems of hexane: ethyl acetate (1:1) and toluene: ethyl acetate (97:3) yielded the most chemicals from chloroform and methanolic extracts of A. indica and E. globulus plants, respectively. On TLC plates, these chemicals were separated, resulting in the discovery of different spots in both leaf extracts. The Rf values of chloroform extract of A. indica run under Hexane: Ethyl acetate (1:1) solvent system was 0.05, 0.11, 0.52, 0.58, 0.74, 0.82, 0.88, and 0.94, respectively, while Rf values of methanol leaf extract of E. globulus run under Toluene: Ethyl acetate (97:3) solvent system was 0.03, 0.07, 0.12, 0.25, 0.37, 0.43, 0.56, 0.62, 0.75, 0.81, 0.87, 0.88 and 0.94 respectively. The results of the investigation will be used to confirm the proper identification of A. indica and E. globulus crude plant extracts. The optimum solvents for extracting antibacterial components from A. indica and E. globulus leaves were chloroform and methanol.

Single-step genome-wide association study for susceptibility to Teratosphaeria nubilosa and precocity of vegetative phase change in Eucalyptus globulus.

Mycosphaerella leaf disease (MLD) is one of the most prevalent foliar diseases of Eucalyptus globulus plantations around the world. Since resistance management strategies have not been effective in commercial plantations, breeding to develop more resistant genotypes is the most promising strategy. Available genomic information can be used to detect genomic regions associated with resistance to MLD, which could significantly speed up the process of genetic improvement. We investigated the genetic basis of MLD resistance in a breeding population of E. globulus which was genotyped with the EUChip60K SNP array. Resistance to MLD was evaluated through resistance of the juvenile foliage, as defoliation and leaf spot severity, and through precocity of change to resistant adult foliage. Genome-wide association studies (GWAS) were carried out applying four Single-SNP models, a Genomic Best Linear Unbiased Prediction (GBLUP-GWAS) approach, and a Single-step genome-wide association study (ssGWAS). The Single-SNP (model K) and GBLUP-GWAS models detected 13 and 16 SNP-trait associations in chromosomes 2, 3 y 11; whereas the ssGWAS detected 66 SNP-trait associations in the same chromosomes, and additional significant SNP-trait associations in chromosomes 5 to 9 for the precocity of phase change (proportion of adult foliage). For this trait, the two main regions in chromosomes 3 and 11 were identified for the three approaches. The SNPs identified in these regions were positioned near the key miRNA genes, miR156.5 and miR157.4, which have a main role in the regulation of the timing of vegetative change, and also in the response to environmental stresses in plants. Our results demonstrated that ssGWAS was more powerful in detecting regions that affect resistance than conventional GWAS approaches. Additionally, the results suggest a polygenic genetic architecture for the heteroblastic transition in E. globulus and identified useful SNP markers for the development of marker-assisted selection strategies for resistance to MLD.

Economic analysis of alternatives for second rotations in Eucalyptus globulus plantations in southeast Uruguay

Eucalyptus globulus is one of the most planted forest species in Uruguay. However, its high susceptibility to diseases has determined that in recent years most plantations reaching harvest are replaced by other species, mainly E. dunnii and E. smithii. The decision whether to maintain the plantation for an additional rotation as coppice crop or to carry out a replanting depends on the expected economic results of both alternatives. Therefore, the objective of this research was to estimate the profitability of a coppice crop of E. globulus and that of a new plantation, with two different species, E. dunnii and E. smithii. In addition, a sensitivity analysis was carried out to study the impact of eventual variations in plantation productivity, in distance to the point of sale, and in the price of wood. Results showed that the three alternatives analyzed are economically viable, but that the management as coppice crop and the replanting with E. smithii are more profitable than replanting with E. dunnii. On the other hand, the coppice management is the alternative that requires less investment and that presents fewer risks, since it is less sensitive to changes in the main variables that determine the economic result.

First report of Phytophthora hibernalis, P. multivora and P. niederhauserii causing root rot and bleeding cankers on Eucalyptus globulus in Portugal

During spring 2022 Phytophthora related-disease symptoms were observed in three Eucalyptus globulus plantations in central Portugal (Aveiro district). Affected trees displayed a range of symptoms including root rot, bleeding cankers and extensive canopy dieback (Figure 1). Average disease incidence and tree mortality rate were estimated as 67 and 20% along three linear transects of 50 m, respectively. In order to isolate the causal agents, rhizosphere and root samples were collected from 20 diseased trees chosen at random in the monitored plantations. Samples were processed as described by Bregant et al. (2023) and cultured on carrot agar at 20°C in the dark. Phytophthora colonies were examined and identifying features recorded and compared with published morphological records of Phytophthora species. The following three species were identified: Phytophthora multivora (12/20 isolates), P. hibernalis (6/20) and P. niederhauserii (2/20) (Figure 2). The identity of all isolates was confirmed by analysis of the internal transcribed spacer region using the universal primers ITS1 and ITS4. DNA extraction, PCR amplification and sequencing were performed according to Bregant et al. (2023). A BLASTn search against the GenBank database showed 100% identity with sequences of the ex-type cultures of P. hibernalis (CBS 114104), P. multivora (CBS 124094) and P. niederhauserii (WPC P10616). The ITS sequence of a representative isolate of each species was deposited in GenBank (P. hibernalis: GenBank Accession No. OQ520314; P. multivora: OQ520315; and P. niederhauserii: OQ520316). The pathogenicity of a representative strain of each Phytophthora species was assessed on one-year-old E. globulus seedlings as described by Bregant et al. (2023). For each isolate ten seedlings were inoculated with an agar-mycelium plug (3 mm diameter) cut from the margin of a four-day-old colony on potato dextrose agar (PDA), whereas ten seedlings used as controls were inoculated with a sterile PDA plug. Seedlings were kept in controlled conditions at 21°C and watered regularly for 30 days. All seedlings inoculated with Phytophthora isolates showed inner bark necrotic lesions spreading up and down from the inoculation point (Figure 3). Average lesion size varied significantly among isolates: P. niederhauserii 28 ±3 mm (average ±SD), P. hibernalis 10 ±3 mm and P. multivora 7 ±3 mm. The control seedlings remained asymptomatic. All Phytophthora species were successfully re-isolated from all inoculated seedlings, thus fulfilling Koch's postulates. This study represents the first report of P. hibernalis, P. multivora and P. niederhauserii on E. globulus in Portugal and in Europe. Recently, two other species, Phytophthora cinnamomi and P. alticola, have been reported as root rot agents of E. globulus in several areas of Portugal (Diogo et al., 2023). The involvement of multiple Phytophthora on E. globulus plantations is of particular concern due to the invasiveness of the species detected and the potential spread of these pathogens into natural ecosystems adjacent to eucalypt plantations. This research has been financially supported by the Land Environment Resources and Health (L.E.R.H.) doctoral course (University of Padova) and project F4F-Forest For Future (CENTRO-08-5864-FSE-000031) from Programa Operacional Regional do Centro (Centro 2020), Portugal 2020 and Fundo Social Europeu. Thanks are due to the Portuguese Foundation for Science and Technology (FCT/MCTES) for the financial support to CESAM (UIDP/50017/2020 + UIDB/50017/2020 + LA/P/0094/2020) and the PhD grants of Sandra Hilário (SFRH/BD/137394/2018) and Eduardo Batista (PD/BD/135535/2018).

Survival of Phytophthora cryptogea and Phytophthora cactorum in Commercial Potting Substrates for Eucalyptus globulus Plants

The international plant trade is considered to be the main pathway causing the spread of oomycetes internationally, especially when live plants are accompanied by soil or potting substrates. Modern, rapid shipping technologies, together with inadequate management practices in nurseries, increase the probability of survival of plant pathogens and the subsequent chances of disease outbreaks in new locations. The survival of two oomycete soil-borne pathogens, Phytophthora cryptogea and Phytophthora cactorum, was studied in two different commercial potting substrates (peat-based and peat-free) in the absence of a plant host under simulated nursery conditions in a glasshouse for 21 months. Colony forming units (CFUs) of both pathogens were recovered 21 months after substrate inoculation, with a decrease in CFUs of between 92 and 99%, depending on the pathogen and substrate. Eucalyptus globulus plants were then planted into these inoculated pots. After 21 months, P. cryptogea and P. cactorum remained capable of producing diseases in E. globulus plants, resulting in up to 30% mortality and an up to 5-fold greater disease severity. These results highlight the ability of these pathogens to survive in the absence of a suitable host plant in potting substrates over time and to then have the capacity to infect a plant. This research adds to the body of essential evidence that is required to develop meaningful management practices and potting substrates at the nursery level to minimize the risk of the spread of oomycetes through the international plant trade.

Effect of Land Use Change on Soil Physico-Chemical Properties under Different Land Use System in Arsi Zone, Oromia Region, Ethiopia

The establishment of artificial plantation using Eucalyptus globules in Ethiopia is becoming economically important for improving the livelihoods of small holder farmers. The species are adapted to different soil depths with varied responses to soil physical and chemical properties that have an implication on the proper management of environmentally sensitive areas. However, the sources of variations of soil physical and chemical properties have not been well investigated and documented for most vertisol in Ethiopia. This study was designed to investigate soil physical and chemical properties variations under different land use systems of cropland, grazing land and trees covered area with Eucalyptus globulus plantation at Gusha Temela Kebele, Arsi Zone and Oromia, Ethiopia. A total of 48 composite soil samples with 4 replicates * 3 treatments * 2 sampling plots * 2 at soil depths of 0–10 and 10–20cm were used for laboratory analysis. Some of the soil physical and chemical properties were analyzed and interpreted including soil texture, bulk density), soil moisture content, pH, available phosphorus (available P), soil organic carbon, total nitrogen and carbon to nitrogen ratio (C/N ratio). The results showed that, except in a few cases, all considered soil properties showed significant differences with land use types and soil depths. Soil Bulk density (r=0.0002), soil moisture content (r&lt;0.0001), soil pH (r&lt;0.0001), available phosphorus (0.0002) and soil organic carbon (r&lt;0.0001) were significantly varied with land use types. Textural fractions of sand, silt and clay showed no significant difference with land use types and soil depths. Although not significant, the clay content was slightly higher under grazing land. On the other hand, soil parameters including bulk density, soil moisture content, pH, soil organic carbon and total nitrogen were higher under grazing land than in the rest land use types and significantly varied with respect to soil depths; greater in the lower soil depth except for soil organic carbon and total nitrogen which were higher in the upper soil depth. The textural fraction of clay across all land use types was higher in the lower depth than in the upper surface layer which could be due to the translocation of this fine particle from the upper soil layer to the lower one. Findings of the present study indicated that land use change has more effect on soil chemical than physical parameters that grazing land is more fertile than other land use types. It implies that management practices significantly influence soil chemical properties variations especially the soil organic carbon concentrations for better employment of land management practices through implementation of climate smart agriculture.

Monitoring the effects of field exposure of acetamiprid to honey bee colonies in Eucalyptus monoculture plantations

Eucalyptus plantations occupy 26 % of Portuguese forested areas. Its flowers constitute important sources for bees and beekeepers take advantage of this and keep their honey bee colonies within or near the plantations for honey production. Nonetheless, these plantations are susceptible to pests, such as the eucalyptus weevil Gonipterus platensis. To control this weevil, some plantations must be treated with pesticides, which might harm non-target organisms. This study aimed to perform a multifactorial assessment of the health status and development of Apis mellifera iberiensis colonies in two similar landscape windows dominated by Eucalyptus globulus plantations - one used as control and the other with insecticide treatment. In each of the two selected areas, an apiary with five hives was installed and monitored before and after a single application of the insecticide acetamiprid (40 g a.i./ha). Colony health and development, resources use, and pesticide residues accumulation were measured. The results showed that the application of acetamiprid in this area did not alter the health status and development of the colonies. This can be explained by the low levels of residues of acetamiprid detected only in pollen and bee bread samples, ~52 fold lower than the sublethal effect threshold. This could be attributed to the low offer of resources during and after the application event and within the application area, with the consequent foraging outside the sprayed area during that period. Since exposure to pesticides in such complex landscapes seems to be dependent on the spatial and temporal distribution of resources, we highlight some key monitoring parameters and tools that are able to provide reliable information on colony development and use of resources. These tools can be easily applied and can provide a better decision-taking of pesticide application in intensive production systems to decrease the risk of exposure for honey bees.

Drivers of Flammability of Eucalyptus globulus Labill Leaves: Terpenes, Essential Oils, and Moisture Content

Mediterranean climate regions have become more vulnerable to fire due to the extreme weather conditions and numerous Eucalyptus globulus plantation areas. The aim of this study is to analyze the fire hazard related to E. globulus in a forest fire scenario, based on the contrast of thermochemical parameters and their relationship with chemical properties, considering the predominant exotic forest species (E. globulus, Pinus radiata, Acacia dealbata, and Acacia melanoxylon) present in the Valparaiso region, Chile. The results revealed that although all of the studied species were highly flammable, E. globulus was extremely flammable, as its leaves contain high concentrations of essential oils, monoterpenes, and sesquiterpenes, which can generate a flammable atmosphere due to their low flashpoint and the strong negative influence shown between the essential oils, volatile terpenes, and limonene concentration. Moreover, the heat of combustion of E. globulus was positively correlated with its high essential oil contents. Finally, all of the studied species had low flashpoints and high heating values; therefore, they are predisposed to ignite in the presence of a heat source, releasing high amounts of energy during combustion, which contributes to the risk of the formation and spread of canopy fires among these tree formations.

Trading a little water for substantial carbon gains during the first years of a Eucalyptus globulus plantation

The establishment and expansion of commercial plantations for timber production and carbon sequestration raises concerns because of their large water use. Eucalyptus globulus (blue gum) is one of the most planted species globally, as it grows rapidly and is adaptable to a range of climatic conditions. The dearth of experimental observations on water use and growth in blue gum plantations in their early years after establishment makes it difficult to develop management practices. This study quantified the trade-offs between water use and carbon assimilation in a blue gum plantation in the first 4 years after establishment. The study site is located in southwest Victoria, Australia, where energy, water and CO2 fluxes were continuously measured above the tree canopy for 4 years after the trees were planted. During the first year after establishment, understory vegetation and ecosystem respiration had a major impact on the net ecosystem exchange (NEE), with the plantation being a net carbon source. Subsequently, the trees started dominating the contributions to NEE, and after approximately 2 years the plantation became a consistent carbon sink. These shifts in NEE were accompanied by smaller increases in annual evapotranspiration rates, which was 70% of the annual precipitation in the first year and 74% in the 3rd year of measurements. As a result, yearly averages of water use efficiency increased from 2.86 gCkg−1H2O in 2018 to 4.3 gCkg−1H2O in 2020, following tree development. This shows a remarkable increase in productivity at the expense of a small amount of water.

The context is more important than the commodity in understanding stakeholder responses to blue gum plantations

ABSTRACT Forestry plantations constitute fertile ground for critical analysis of land use conflict. Policy-makers are increasingly recognising the need to address controversial issues in the plantation forestry sector. However, these efforts are often grounded in short-term analyses, resulting in static or inappropriate responses to a dynamic commodity environment. This research article proposes that combining cognitive and social research approaches can elucidate place-based land-use conflicts that at their root, are about more than just the one particular commodity under examination. We explore stakeholders’ perceptions and attitudes around Tasmanian blue gum (Eucalyptus globulus) plantations in a region that has witnessed three radically different social-economic stages of blue gum plantation growth and management over the last 25 years. Our findings show that individual perceptions and attitudes over time are most closely related to the economic characteristics of blue gum plantations than to any other factor. By extension, market instability shapes popular narratives around blue gum plantations. We conclude that the analysis of conflicts associated with long-established forestry plantations should encompass an understanding of community members’ worldviews and emotions in addition to economic analyses in order to adequately explain conflicts.

Streamflow response to native forest restoration in former Eucalyptus plantations in south central Chile

AbstractGlobal increases in intensive forestry have raised concerns about forest plantation effects on water, but few studies have tested the effects of plantation forest removal and native forest restoration on catchment hydrology. We describe results of a 14‐year paired watershed experiment on ecological restoration in south central Chile which documents streamflow response to the early stages of native forest restoration, after clearcutting of plantations of exotic fast‐growing Eucalyptus, planting of native trees, and fostering natural regeneration of native temperate rainforest species. Precipitation, streamflow, and vegetation were measured starting in 2006 in four small (3 to 5 ha) catchments with Eucalyptus globulus plantations and native riparian buffers in the Valdivian Coastal Reserve. Mean annual precipitation is 2500 mm, of which 11% occurs in summer. Streamflow increased, and increases persisted, throughout the first 9 years of vigorous native forest regeneration (2011 to 2019). Annual streamflow increased by 40% to &gt;100% in most years and &gt;150% in fall and summer of some years. Streamflow was 50% to 100% lower than before treatment in two dry summers. Base flow increased by 28% to 87% during the restoration period compared to pre‐treatment, and remained elevated in later years despite low summer precipitation. Overall, these findings indicate that removal of Eucalyptus plantations immediately increased streamflow, and native forest restoration gradually restored deep soil moisture reservoirs that sustain base flow during dry periods, increasing water ecosystem services. To our knowledge this is the first study to assess catchment streamflow response to native forest restoration in former forest plantations. Therefore, the results of this study are relevant to global efforts to restore native forest ecosystems on land currently intensively managed with fast‐growing forest plantations and may inform policy and decision‐making in areas experiencing a drying trend associated with climate change.

Impact of Roadside Drying on Delivered Costs for Eucalyptus globulus Logging Residue and Whole Trees Supplying a Hypothetical Energy Plant in Western Australia Using a Linear-Programming Model

Australia’s large potential forest bioenergy resource is considerably underutilised, due largely to its high delivered costs. Drying forest biomass at the roadside can potentially reduce its delivered cost through weight reduction and increased net calorific value. There has been little research on the impact of roadside drying for Australian conditions and plantation species. This study compared delivered costs for three forest biomass types—Eucalyptus globulus plantation whole trees and logging residue (LR)-disaggregated (LR conventional) or aggregated (LR fuel-adapted)—and three roadside storage scenarios—no storage, ≤two-month storage and optimal storage—to supply a hypothetical thermal power plant in south-west Western Australia. The study was performed using a tactical linear programming tool (MCPlan). Roadside storage reduced delivered costs, with optimal storage (storage for up to 14 months) producing the lowest costs. Delivered costs were inversely related to forest biomass spatial density due to transport cost reductions. Whole trees, which had the highest spatial density, stored under the optimal storage scenario had the lowest delivered costs (AUD 7.89/MWh) while LR conventional, with the lowest spatial density, had the highest delivered costs when delivered without storage (AUD 15.51/MWh). For both LR types, two-month storage achieved ~60% of the savings from the optimal storage scenario but only 23% of the savings for whole trees. The findings suggested that roadside drying and high forest biomass spatial density are critical to reducing forest biomass delivered costs.

The Tolerance of Eucalyptus globulus to Soil Contamination with Arsenic.

The contamination of abandoned mining areas is a problem worldwide that needs urgent attention. Phytoremediation emerges as a successful method to extract different contaminants from the soil. In this context, Eucalyptus globulus plants growing in soils artificial contaminated with arsenic (As) were used to access its phytoremediation capabilities. The effects of As on photosynthetic performance were monitored through different physiological parameters, whereas the uptake and translocation of As and the putative effects on calcium, iron, potassium, and zinc levels on plants were evaluated by X-ray fluorescence analysis. Root system is the major accumulator organ, while the translocation to the above-ground organs is poor. In the end of the experiment, the root biomass of plants treated with 200 μg As mL−1 is 27% and 49.7% lower than equivalent biomass from plants treated with 100 μg As mL−1 and control plants, respectively. Each plant can accumulate 8.19 and 8.91 mg As after a 6-month period, when submitted to 100 As and 200 As, respectively. It seems to exist an antagonistic effect of As on Zn root uptake by E. globulus. In general, the tested concentrations do not influence negatively plant metabolism, indicating that this species is suitable for plantation in contaminated areas.

Economics of forest biomass for bioenergy: potential site preparation savings from coarse woody harvesting residue removal in a short-rotation Eucalyptus globulus (Labill.) plantation

The study used time studies and cost analysis to assess potential economic benefits from site preparation cost reductions resulting from producing coarse woody harvesting residue (CWHR) for bioenergy. In contrast, previous studies have predominantly used anecdotal estimates of site preparation costs.The study was performed in a recently clearfelled 15-year-old plantation of Eucalyptus globulus (Labill) in Tasmania, Australia. The study area consisted of the control area (0.51 ha), containing ~35 m3 ha-1 of CWHR and the CWHR harvest area (2.47 ha), containing &amp;le;12 m3 ha-1 of CWHR. The control area had been harvested with a harvester &amp;ndash; forwarder system, which left all harvesting residue (HR) onsite, where-as the CWHR harvest area had been harvested with a feller-buncher &amp;ndash; skidder &amp;ndash; processor system which removed most of the HR. The latter site was used to simulate an area where CWHR had been harvested. The study examined productivities and costs of machines performing site preparation in each area. The preparation of the control area site was performed with an excavator that windrowed CWHR, fol-lowed by a skidder-mounted plough constructing planting furrows. Residual CWHR post-windrowing was &lt;1 m3 ha-1. Productivities and costs were 0.53 ha PMH0-1 and AUD$319 ha-1 for the excavator and 1.1 ha PMH0-1 and AUD$139 PMH0-1 for the skidder-mounted plough. The excavator was not required in the CWHR harvest area. In this area, skidder-mounted plough productivity and cost were 1.16 ha PMH0-1 and AUD$109 ha-1 suggesting CWHR reduction to &amp;le;12 m3 ha-1 could reduce site preparation costs by AUD$319 ha-1. Further studies on costs and revenues associated with CWHR removal and sale are required to determine net economic benefits and determine excavator cost and productivity for a range of CWHR quantities.

ARTIFICIAL NEURAL NETWORKS (ANN) FOR HEIGHT ESTIMATION IN A MIXED-SPECIES PLANTATION OF Eucalyptus globulus LABILL AND Acacia mearnsii DE WILD

ABSTRACT The objective of this study is to evaluate the fit of Artificial Neural Networks (ANN) for height estimation and evaluation of the effects of consortium in a mixed-species plantation of Eucalyptus globulus (E) and Acacia mearnsii (A). The experiment was installed in 2005, on two farms in the municipality of Piratini - RS, where was planted the species Eucalyptus globulus (E) and Acacia mearnsii (A), in monoculture and mixed in simple lines (50%E:50%A - SL), and double lines (50%E:50%A - DL). The training and evaluation of the networks were made in R-project with the package neuralnet. All ANNs, from the simplest to the most complex, showed high values for Rŷy and low for Syx, BIAS and RMSE, with superior results in ANN 3, 4, and 6, which demonstrates that the information of DBHmin, DBHmean, and DBHmax were important stand attributes. Furthermore, the ANNs were able to capture the different growth patterns shown by the species in the different forms of consortiums, therefore is indicated for the height estimation in monocultures and mixed plantations of Eucalyptus globulus and Acacia mearnsii, and only one ANN would be necessary to represent the entire population.