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The resilience of forests worldwide is challenged by climate change. Large-scale tree mortality and dieback events have been documented across continents in recent decades. The adaptive capacity of forests is important for predicting forest resistance and resilience to future climates yet remains largely unknown. We grew 12 populations of a widespread foundation tree species (Corymbia calophylla), originating from different temperature and rainfall regimes, in two common garden trials in Western Australia that had similar temperature but contrasting rainfall conditions. We quantified intraspecific trait variation at these two sites to estimate genetically determined trait variation with climate origin (genetic adaptation) and trait variation associated with environment (phenotypic plasticity). We aimed to determine the 1) contribution of genetic and environmental factors on growth, functional, and physiological trait variation; 2) coordination of leaf traits within the context of the leaf economic spectrum (LES) in variable rainfall conditions; and 3) role of local or regional climate adaptation influencing tree growth and water use efficiency. Growth and physiological traits were differentially expressed across populations and sites, highlighting the importance of genetic adaptation and phenotypic plasticity. Leaf traits reflected a more water conservative strategy with higher water use efficiency, high foliar nitrogen content, and low specific leaf area, as predicted by the LES, in trees at the dry site measured in autumn after the warm summer. Local adaptation was detected in growth and leaf water use efficiency traits at the regional climate, not the local population, scale. Plants from the cool region had greater performance than those from the warm region in most plant traits. Home-site rainfall was not a good predictor of trait expression. The capacity of C. calophylla to respond to low water availability through genetic adaptation and phenotypic plasticity may enable it to maintain optimal performance in drier conditions associated with climate change. • Leaf traits were coordinated and reflected a water conservative strategy. • Growth and leaf water use efficiency traits were locally adapted. • Plant traits expressed phenotypic plasticity to site rainfall. • Regional temperature was a stronger driver of plant traits than rainfall. [ABSTRACT FROM AUTHOR]

• The retention of net rhizodeposition in the soil organic matter fractions was investigated. • Net rhizodeposition was predominantly retained as mineral-associated organic matter (MAOM). • Al and Fe reactive phases retained a substantial portion of the net rhizodeposition within MAOM but not the majority of it. • Rhizodeposition increased microbial PLFAs in the root vicinity, with a prominent incorporation into the fungal community. Net rhizodeposition corresponds to the portion of living root carbon (C) that remains in the soil after microbial processing and partial decomposition. Although it is assumed that this C input exerts an important role in the formation of soil organic matter (SOM), its contribution to distinct SOM pools is still not fully understood. In this study, we aimed to (i) quantify the retention of net rhizodeposition C in the different SOM fractions and in reactive Al and Fe mineral phases and (ii) investigate how rhizodeposition drives the spatial distribution of microbial communities in the rhizosphere. To track the transfer of net rhizodeposition into the soil, we used artificially labeled eucalypt (Eucalyptus spp.) seedlings under a 13C-CO 2 atmosphere (multiple-pulse labeling). Combining physical SOM fractionation and the chemical extraction of aluminum (Al) and iron (Fe) reactive phases, we studied the distribution of net rhizodeposition into different soil fractions. We also assessed the 13C incorporation into microbial phospholipid fatty acids (PLFAs) at different distances from the roots. Our results show that 76 % of the net rhizodeposition 13C was retained within the mineral-associated organic matter (MAOM) fraction. About 28 % of net rhizodeposition 13C within the MAOM fraction was retained within the Al and Fe reactive phases, indicating that this is a sizeable mechanism for the retention of net rhizodeposition in soil. Rhizodeposition increased the abundance of microbial PLFAs exclusively in the soil close to the roots (0–4 mm), with prominent incorporation of net rhizodeposition 13C into fungal biomarkers. Overall, our findings underscore the importance of mineral associations for the retention of net rhizodeposition in the soil. We also highlight the role of fungi in transferring the root-derived C beyond the root vicinity and promoting the formation of occluded SOM. [ABSTRACT FROM AUTHOR]

Understanding the effect of planting densities and species proportions on light absorption and light use efficiency can help to improve the management of mixed-species forest plantations. Our study aimed to disentangle the role of light interception and light use efficiency (LUE) on the biomass production of Eucalyptus grandis (E), a highly productive species in tropical conditions, and Acacia mangium (A), a N 2 -fixing species, in monocultures and mixed-species plantations for contrasting planting densities. A randomized block experiment set up over 4 ha in southern Brazil was intensively monitored for 14 months at mid rotation. The absorbed photosynthetically active radiation (APAR) was simulated for each tree of the experiment using the tri-dimensional MAESPA model parameterized with detailed in situ measurements of tree and foliage. LUE for stem wood production was estimated as the ratio of measured stem biomass production (SBP) and simulated APAR. The APAR of Eucalyptus trees did not significantly differ between monocultures and mixed plantations, the reduction of Eucalyptus density being compensated by an increase in light absorption of Eucalyptus individuals. The LUE of Eucalyptus trees in monoculture and mixed-species stands was found to be comparable only at low planting densities. The replacement of Eucalyptus trees with Acacia trees resulted in a reduction in Eucalyptus LUE only at high planting density. The SBP of Eucalyptus trees was mainly explained by differences in APAR, while both APAR and LUE explained the SBP of Acacia trees. The maximum stand production was obtained with monoculture of Eucalyptus at high density and no mixture reached this productivity. Reducing the proportion of Eucalyptus in mixture lead to a substantial decrease in stand production at high planting density due to a decrease in LUE, while this stand production reduction was offset at low planting density, underlying a higher diversity effect at low planting density. In the perspective of increasing diversity in forest plantations to foster multifunctionality, mixed plantations of Acacia and Eucalyptus at low planting density can be an interesting option to maintain a relatively high productivity, which is similar to Eucalyptus monocultures at the same low planting density. • APAR, wood growth and LUE were estimated in monocultures and mixed-species plantations. • These variables were analysed in function of the species proportion and planting densities. • The maximum stand production was for Eucalyptus monoculture at highest density. • At the low tree density in a mixed-species stand, Eucalyptus had similar productivity to that in pure than Eucalyptus at low density". [ABSTRACT FROM AUTHOR]

• We identified 76 studies of nest boxes and birds in commercially managed forests. • There is growing evidence that nest boxes benefit birds in commercially managed forests. • Most studies explore insectivores in pine forests of the Northern Hemisphere. Nest boxes are widely used to supplement natural tree cavities used by fauna, particularly in "working lands" where large, old trees are cleared or harvested. Commercially managed forests comprise large areas of global forest cover and nest boxes provide an opportunity to encourage biodiversity in areas where trees are harvested before natural cavities form. Here, we used a systematic review to provide a global overview of the scientific literature on nest boxes and bird conservation within commercially managed forests. Our systematic review identified 76 studies exploring the influence of nest boxes on birds in commercially managed forests, ranging from studies of individual birds to whole communities. Insectivorous birds were the most common reported users of nest boxes, and studies that incorporate a before and after period provide one line of evidence that nest boxes enhance bird occupancy and survival. However, only a small number of bird species have been observed using nest boxes and most studies were conducted within pine-dominated forests in Europe and North America. We recommend future research to develop knowledge of a wider range of bird taxa and commercially managed forest types. Further, we advocate for testing different types of nest box designs, materials, and spatial arrangements to improve conservation outcomes. This will help to ensure nest boxes, in combination with ecological restoration and a suite of other conservation actions, enhance biodiversity and the ecosystem functions provided by birds, such as pest control. [ABSTRACT FROM AUTHOR]

An environmental history is presented from Girraween Lagoon, Darwin region of the Northern Territory, Australia. Pollen and charcoal analysis of a 5-meter sediment core provides a record of vegetation change, fire history and climate spanning 12,700 cal BP to the present day. This study focusses on tree-grass vegetation dynamics, eucalypt to non-eucalypt plant interactions, and climate–fire–human relationships in an area where few long-term savanna records exist. The dataset suggests wetlands experienced alternating episodes of ephemeral waterlogging and seasonal inundation due to post-glacial monsoon variability up until permanent inundation from approximately 6000 cal BP. The surrounding catchment transformed from a terminal Pleistocene–early Holocene wooded-savanna to a later Holocene open forest. This increase in woody cover was a prominent site feature, primarily driven by climate–moisture availability. In turn, the extent of fire and fire impact, is a function of climate–vegetation feedbacks. Such interplay between fire history, climate change and vegetation pattern was also influenced by more intense human management of the area, in the last 4000 years of the record. It is proposed Girraween may have become a much-socialized and managed human landscape in this late Holocene phase. Results provide essential baseline data describing savanna dynamics linked to contemporary ecological observation, understanding and management goals, and serves as an important resource for the Quaternary sciences and archeology of northern Australia. • Paleoecological insight in an area where few long-term savanna records exist. • Increase in Holocene woody cover a prominent site feature. • Moisture has been the primary driver of Holocene vegetation dynamics. • Extent of fire and fire impact, is a characteristic of climate and resultant vegetation. • Lagoon forms an important human freshwater source during variable Holocene climate. [ABSTRACT FROM AUTHOR]

• The new tri-PRI tracks leaf-level xanthophyll epoxidation state dynamics in a mature eucalypt forest. • Indices using two-bands do not perform well. • The new formulation is robust to constitutive pigment pool size effects across the canopy profile. • tri-PRI achieved results comparable to PLSR and continuum removal using full spectrum data. Plants actively regulate excess absorbed energy to protect photosynthetic machinery through heat dissipation in a process known as non-photochemical quenching (NPQ), a process useful for quantifying plant health and productivity. NPQ can be indirectly measured in the visible wavelengths between 500 nm and 560 nm, most commonly through the Photochemical Reflectance Index (PRI). However, there remains a lack of consensus regarding the optimal functional form and band selection to calculate PRI for the purpose of measuring NPQ mechanisms. Here, we quantitatively evaluate the effectiveness of leaf-level parametric and non-parametric spectral formulations, band locations, and number of bands to track the xanthophyll pigment cycle in a tall mature Eucalypt forest. Subsequently, our recommended approach is the new 'tri-PRI' index robust to constitutive pigment pool sizes across the canopy profile. tri-PRI is a Triangular Vegetation Index (TVI) (tri-PRI = 0.5[(520 - 490)(R 545nm - R 490nm) - (545 – 490)(R 520nm - R 490nm)]) using three reflectance bands around 490 nm, 520 nm and 545 nm, and has a physiological photosynthetic basis. We found that tri-PRI significantly outperformed PRI and other two band combinations for quantifying the xanthophyll EPoxidation State 'EPS' (tri-PRI R2 = 0.75 versus PRI R2 = 0.23), as well as the Φ NPQ and Φ PSII active chlorophyll fluorescence quenching yields. The new band placement enhanced the dynamic EPS absorption peak, while the third band provided an additional normalisation to minimise the confounding effects of pigments with overlapping spectral features. tri-PRI also performed comparably to parametric and non-parametric hyperspectral techniques and formulations using continuous spectral regions, highlighting the utility of targeted multispectral indices over hyperspectral approaches. This leaf-level study represents a foundational step toward indirectly measuring dynamic photosynthetic activity across the canopy profile in a tall mature Eucalypt forest to inform upscaling efforts from above-canopy remote sensing platforms. The application of tri-PRI and other top-performing multi-band TVI formulations for predicting EPS presented here should be explored across different canopy types, temporal-, and spatial scales. [ABSTRACT FROM AUTHOR]

Highlights • Subgenus Eucalyptus trees contain high foliar amounts of medicinal pinocembrin. • Some species also contain high amounts of related O - and C -methylated flavanones. • High-yielding species can be selected to establish commercial flavanone plantations. Abstract Plant-derived flavanones such as pinocembrin and related methylated forms are of interest for their potential medicinal use. Commercial sources of these compounds are limited, but some trees in genus Eucalyptus subgenus Eucalyptus (family Myrtaceae) show promise due to their high foliar flavanone content and growth rate, particularly when grown in coppice cultivation. As a first step to developing commercial Eucalyptus plantations for flavanone production, this research aimed to identify high-yielding species. Foliar flavanones were quantified in 41 species and subspecies from three major sections within the subgenus. Pinocembrin concentrations were highest in two subspecies of E. preissiana with notably high levels of 15 and 18 mg g–1 dry weight (DW). The highest concentrations of 7- O -methylpinocembrin (12 mg g–1 DW) and 5,7- O -dimethylpinocembrin (20 mg g–1 DW) were found in E. croajingolensis and E. oreades , respectively. In addition, two C -methyl flavanones were identified in Eucalyptus for the first time: 6- C -methylpinocembrin (7 mg g–1 DW) in E. megacarpa and 6,8- C -dimethylpinocembrin (6 mg g–1 DW) in E. agglomerata. In general, flavanone profiles for closely related eucalypts such as subspecies were very similar. Moreover, species fit into three distinct categories - those with high concentrations of relatively pure non-methylated pinocembrin, those with highly abundant O -methyl flavanones, or those with abundant C -methyl flavanones. Saplings of two selected species grown in a trial plot largely reflected adult tree flavanone profiles, albeit at lower levels attributed to ontogenetic effects. In conclusion, we have shown that many species of Eucalyptus are abundant sources of promising medicinal flavanones. This work will enable selection of high-yielding species and genotypes for growth-rate assessment trials and the future establishment of commercial plantations. [ABSTRACT FROM AUTHOR]

Highlights • One feature of the perennial lifestyle of woody plants is nutrient storage in wood and bark. • This study aimed to test whether the formation of a stem is required to make plant nutrition independent of soil conditions. • Mineral nutrition and a set of physiological parameter of E. pauciflora and P. alpestre were determined. • Formation of a stem is a necessity for long-lived plants to enable growth largely independent of soil P and N availability. Abstract We sought to elucidate if the perennial lifestyle per se , or lifeform, enhances independence of soil nutrient availability. We measured parameters of CO 2 fixation and electron transport, stomatal conductance, P and N nutrition, as well as integrative water relations (δ 13C abundance) of an overstory tree (Snow Gum; Eucalyptus pauciflora, Sieber ex Spreng.) and a perennial understory shrub (Alpine Shaggy-pea; Podolobium alpestre F. Muell.) at two Australian field sites with different soil nutrient availability, but otherwise similar environmental conditions. Snow Gums are renowned for their longevity, including the ability to re-sprout profusely after fire, while Alpine Shaggy-pea has a relatively short lifespan, and regenerates from seed after fire. Photosynthesis parameters of P. alpestre were more sensitive to soil properties than for E. pauciflora. P and N status of leaves and roots of E. pauciflora were comparable at both sites, whereas P and N status of P. alpestre reflected their availability in the soil. Differences in δ 13C abundance of the two species studied indicated the use of different water sources at both field sites. These results suggest that long-lived plants with the capability to recycle nutrients from woody tissues, can grow largely independent of soil P and N availability. [ABSTRACT FROM AUTHOR]

Highlights • N cycling was compared in Eucalyptus (100E), Acacia mangium (100A) and mixed-species plantations (50A50E). • Atmospheric N fixation in 50A50E and 100A was 250 and 400 kg N ha−1 rotation−1, respectively. • N contents in litterfall and soil N mineralization rates were 60% higher in 100A than in 100E. • Soil C and N stocks were dependent on soil texture but not influenced by tree species. Abstract Mixing N-fixing trees with eucalypts is an attractive option to improve the long-term soil N status in fast-growing plantations established in tropical soils. A randomized block design was replicated at four sites in Brazil to compare the biogeochemical cycles in mono-specific stands of Eucalyptus (100E) and Acacia mangium (100A) with mixed-species plantations in a proportion of 1:1 (50A50E). Our study aimed to assess the effects of introducing A. mangium trees in Eucalyptus plantations on atmospheric N 2 fixation, N cycling and soil organic matter stocks. Litterfall and soil N mineralization were measured over the last two years of the rotation (4–6 years after planting). Aboveground N accumulation in the trees and C and N stocks in the forest floor and in the top soil were intensively sampled at harvesting age. N 2 fixation rates were estimated using the natural abundance of 15N as well as by the difference between total N stocks in 100A and 50A50E relative to 100E (accretion method). While the 15N natural abundance method was unsuitable, the accretion method showed consistently across the four sites that atmospheric N fixation reached about 250 and 400 kg N ha−1 rotation−1 in 50A50E and 100A, respectively. Except at one site with high mortality, N contents within trees at harvesting were approximately 40% higher in 100A than in 100E. Mean N contents in litterfall and N mineralization rates were about 60% higher in 100A than in 100E, with intermediate values in 50A50E. The amounts of N in litterfall were much more dependent on soil N mineralization rates for acacia trees than for eucalypt trees. Soil C and N stocks were dependent on soil texture but not influenced by tree species. N budgets over a 6-year rotation were enhanced by about 65 kg N ha−1 yr−1 in 100A and 40 kg N ha−1 yr−1 in 50A50E relative to monospecific eucalypt plantations. Introducing N-fixing trees in eucalypt plantations might therefore contribute to reducing the need for mineral N fertilization in the long-term. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • We used ALS, WorldView-2 and SAR imagery to upscale tree numbers. • ALS derived tree numbers were used for training a random forest regressor. • We upscaled tree numbers with R2 of 0.61 and normalized RMSE of 62%. • The ALS and WorldView-2 predictors were the best for estimating tree numbers. • The SAR predictors alone were unable to estimate tree numbers reliably. Abstract Detailed information on the number and density of trees is important for conservation and sustainable use of forest resources. In this respect, remote sensing technology is a reliable tool for deriving timely and fine-scale information on forest inventory attributes. However, to better predict and understand the functioning of the forest, fine-scale measures of tree number and density must be extrapolated to the forest plot or stand levels through upscaling. In this study, we compared and combined three sources of remotely sensed data, including low point density airborne laser scans (ALS), synthetic aperture radar (SAR) and very-high resolution WorldView-2 imagery to upscale the total number of trees to the plot level in a structurally complex eucalypt forest using random forest regression. We used information on number of trees previously derived from high point density ALS as training data for a random forest regressor and field inventory data for validation. Overall, our modelled estimates resulted in significant fits (p < 0.05) with goodness-of-fit (R2) of 0.61, but systematically underestimated tree numbers. The ALS predictor variables (e.g. canopy cover and height) were the best for estimating tree numbers (R2 = 0.48, nRMSE = 61%), as compared to WorldView-2 and SAR predictor variables (R2 < 0.35). Overall, the combined use of WorldView-2, ALS and SAR predictors for estimating tree numbers showed substantial improvement in R2 of up to 0.13 as compared to their individual use. Our findings demonstrate the potential of using low point density ALS, SAR and WorldView-2 imagery to upscale high point density ALS derived tree numbers at the plot level in a structurally complex eucalypt forest. [ABSTRACT FROM AUTHOR]

Plantation forestry accounts for a rapidly increasing proportion of the global wood supply, which makes it especially urgent to reduce its environmental impact. In that regard, much benefit can be obtained by reducing fossil fuel consumption during tree harvesting operations, which represent a main contributor to CO 2 emissions in the plantation wood supply chain. This test was conducted in Brazil on three industrial delimber-debarker-chippers (Peterson Pacific DDC 5000H), which are the largest fuel consumers among the machines used for harvesting plantation eucalypt. Production, fuel use and product quality data were collected for each machine on a daily basis under the standard 2100 RPM engine setting, and under a new reduced engine setting (1820 RPM). Fuel consumption and productivity data were collected continuously for 30 days (triple shift) for each machine and treatment. Under the new treatment, fuel use and emissions were reduced in all machines, without any negative effects on productivity and product quality. In fact, both debarking performance and chip size distribution were improved. The experiment showed how a simple adjustment of engine setting may cut fuel consumption and CO 2 emissions by an average of 17% over the control values. Engine setting adjustment is a basic measure, easy to implement and suitable for application to a wide range of activities and environments. [ABSTRACT FROM AUTHOR]

The so-called clumping factor (Ω) quantifies deviation from a random 3D distribution of material in a vegetation canopy and therefore characterises the spatial distribution of gaps within a canopy. Ω is essential to convert effective Plant or Leaf Area Index into actual LAI or PAI, which has previously been shown to have a significant impact on biophysical parameter retrieval using optical remote sensing techniques in forests, woodlands, and savannas. Here, a simulation framework was applied to assess the performance of existing in situ clumping retrieval methods in a 3D virtual forest canopy, which has a high degree of architectural realism. The virtual canopy was reconstructed using empirical data from a Box Ironbark Eucalypt forest in Eastern Australia. Hemispherical photography (HP) was assessed due to its ubiquity for indirect LAI and structure retrieval. Angular clumping retrieval method performance was evaluated using a range of structural configurations based on varying stem distribution and LAI. The CLX clumping retrieval method (Leblanc et al., 2005) with a segment size of 15° was the best performing clumping method, matching the reference values to within 0.05 Ω on average near zenith. Clumping error increased linearly with zenith angle to >0.3 Ω (equivalent to a 30% PAI error) at 75° for all structural configurations. At larger zenith angles, PAI errors were found to be around 25–30% on average when derived from the 55–60° zenith angle. Therefore, careful consideration of zenith angle range utilised from HP is recommended. We suggest that plot or site clumping factors should be accompanied by the zenith angle used to derive them from gap size and gap size distribution methods. Furthermore, larger errors and biases were found for HPs captured within 1 m of unrepresentative large tree stems, so these situations should be avoided in practice if possible. [ABSTRACT FROM AUTHOR]

We report the association of Cristulariella moricola (Hino) Redhead with a zonate leaf spot on Eucalyptus benthamii (Myrtaceae). We observed the disease outbreak across a series of experimental E. benthamii plantings in Barnwell County, South Carolina, USA in October 2015. The disease caused nearly complete foliar necrosis of most trees in one experimental planting, but disease incidence remained at low levels (<10% of foliage affected in most trees) in other plantings. Disease development coincided with periods of extended rainfall, which has also been observed in outbreaks of zonate leaf spot caused by C. moricola in other tree species. [ABSTRACT FROM AUTHOR]

Research has been undertaken on the hydrological and erosional impact of forest fires, but remarkably little work has been conducted on salvage logging operations that often follow them. We assessed the effects of mechanical salvage logging following wildfire on soil physical properties, ground cover, and runoff and erosion response on a eucalypt stand in Portugal. We compared two levels of mechanical disturbance, skid trails by a wheeled forwarder tractor (“skid_low”) and skid trails by the same tractor followed by a tracked feller-buncher (“skid_high”) with control conditions (no mechanical disturbance). Three plots (16 m 2 ) by level of soil disturbance were installed after a moderate intensity fire and subsequent logging operations, and monitored during the first post-fire year. In two control and two skid_low plots runoff was also measured. Soil bulk density was higher with increasing mechanical disturbance. Soil compaction reduced porosity 7–16%, but as the control porosity was 70%, the reduced porosity still was 60–65%. Soil resistance to penetration significantly increased for the most disturbed area, whereas soil shear strength was significantly reduced in the intermediate disturbance level. Mechanical disturbance did not induce significant effects on soil moisture or ground cover. Initial greater coverage by bare soil in the disturbed plots compared to the control was compensated by a more rapid vegetation recovery in those plots. Annual runoff amount was not higher at the skid-low than at control plots. Absence of runoff difference was due to high soil porosity of 65%, even after tractor trafficking, and a greater surface roughness on the skid_low plots compared to the control. Sediment production increased with increasing soil disturbance. The mean sediment rate was 1.6–3 times greater for the disturbed than the control plots. This increase could be explained by the higher soil compaction and reduced soil shear strength on the mechanically disturbed plots and initial differences in ground cover. Organic matter content of the eroded sediments was higher on the control than the disturbed plots, due to initial higher ash cover on the control plots. Overall, sediment production was significantly related to rainfall intensity and reduced by vegetation regrowth. Sediment rates tend to decrease with time since the initial fire and logging disturbance, highlighting the importance of a rapid implementation of erosion control measures. Specific management practices are needed to minimize the impacts of logging in burnt soils which are already subject to greater erosion risk and soil degradation. [ABSTRACT FROM AUTHOR]

A wildfire which overran a sensor network site provided an opportunity (a natural experiment) to monitor short-term post-fire impacts (immediate and up to three months post-fire) in remnant eucalypt woodland and managed pasture plots. The magnitude of fire-induced changes in soil properties and soil microbial communities was determined by comparing (1) variation in fire-adapted eucalypt woodland vs. pasture grassland at the burnt site; (2) variation at the burnt woodland-pasture sites with variation at two unburnt woodland-pasture sites in the same locality; and (3) temporal variation pre- and post-fire. In the eucalypt woodland, soil ammonium, pH and ROC content increased post-fire, while in the pasture soil, soil nitrate increased post-fire and became the dominant soluble N pool. However, apart from distinct changes in N pools, the magnitude of change in most soil properties was small when compared to the unburnt sites. At the burnt site, bacterial and fungal community structure showed significant temporal shifts between pre- and post-fire periods which were associated with changes in soil nutrients, especially N pools. In contrast, microbial communities at the unburnt sites showed little temporal change over the same period. Bacterial community composition at the burnt site also changed dramatically post-fire in terms of abundance and diversity, with positive impacts on abundance of phyla such as Actinobacteria, Proteobacteria and Firmicutes. Large and rapid changes in soil bacterial community composition occurred in the fire-adapted woodland plot compared to the pasture soil, which may be a reflection of differences in vegetation composition and fuel loading. Given the rapid yet differential response in contrasting land uses, identification of key soil bacterial groups may be useful in assessing recovery of fire-adapted ecosystems, especially as wildfire frequency is predicted to increase with global climate change. [ABSTRACT FROM AUTHOR]

Introducing nitrogen-fixing species (NFS) in eucalypt plantations is a useful practice to compensate nitrogen loss at harvest, reduce fertilizer inputs, improve soil fertility and sustain forest productivity in low input systems. Nitrogen (N) and carbon (C) were evaluated in the active part of soil organic matter (SOM) i.e., the particulate organic matter (POM), which was obtained after soil (0–0.05 m) physical fractionation at the end of a first 7-year rotation (R1Y7) and at year 2 of a second rotation (R2Y2) in pure acacia (100A), pure eucalypt (100E) and mixed-species (50A50E) stands in an experimental plantation established on an Arenosol in the Congolese coastal plains. N concentration (in g kg −1 of soil) was higher in coarse POM (cPOM, 4000–250 μm) in 100A and 50A50E compared to 100E at 2YR2, while no difference was found in fine POM (fPOM, 250–50 μm) and in the organo-mineral fraction (OMF, < 50 μm). N content in cPOM was more than 3 times higher at R2Y2 than at R1Y7. A slight increase was also observed in fPOM, while no difference was observed in OMF between R1Y7 and R2Y2. Lower C:N ratios in the two POM fractions in 100A and, to a lesser extent, in 50A50E compared to 100E suggests an improved soil N status after acacia trees have been introduced in eucalypt plantations. The lack of difference in N content of coarse POM between 100A and 50A50E at R1Y7, despite higher amount of N in the forest floor and N returning to the soil (harvest residues and litterfall) in 100A than in 50A50E, suggests a faster cycling of nitrogen under acacia than under eucalypt. [ABSTRACT FROM AUTHOR]

• The parameters a s , n s , η Rx , η Rn and t c were selected to be predicted by artificial neural networks (ANN). • ANN allows relating different types of variables generating greater precision in the 3-PG parameterization. • Different alternatives in database structure can be used in the ANN training or application to predict the 3-PG parameters. • With the use of ANN, it is possible to calibrate 3-PG model for managing forests in different regions. Understanding how the physiological processes of trees are affected by the environment or silvicultural practices is important for forest management, which requires process-based models. It enables the evaluation of the growth of a forest under different scenarios. The 3-PG model has been widely used all over the world, justified by its simplicity and efficiency, as it uses a more accessible language and fewer parameters than other process-based models. It is a model of greatest interest for forest management because it enables the use of allometric equations to calculate variables of interest in this area, such as the average diameter at 1.30 m height (DBH), total height and stand volume. The 3-PG parameterization is essential to guarantee the model's good performance; however, in some cases, when observed data are not available, values from the literature is used or calibration is performed. In general, there is a mixture of these alternatives in the same parameterization, but some of the parameters generate greater sensitivity in some outputs or change according to site characteristics. In the present work, we analyzed the efficiency of artificial neural networks to predict some of the parameters pointed out in the literature as being of the greatest importance for 3-PG using climate and process variables as inputs. For this, a simulated database was generated, using 16 parameterizations of 3-PG, for different regions of Brazil. The parameters values of the DBH function (a s and n s), minimum and maximum fraction of biomass allocated to the root (η Rn and η Rx), and age at full canopy cover (t c) were associated with this database. The Artificial Neural Networks (ANNs) were trained using the database with parameter repetition over time and with the average condition of each site. In the second case, training was performed using 100% of the data, and validation was performed using a simulated database. The efficiency of neural networks has been proven in predicting the parameters a s , n s and η Rx , with validation root mean squared error (RMSE) of 6.9%, 6.9% and 4.8%, in the first training approach, respectively. For training based on sites average condition RMSE was 20.7%, 3.0% and 8.8%, for a s , n s and η Rx , respectively. The study showed the need for more scientific investigation for the other parameters, including information and input variables such as soil characteristics. As demonstrated in this study, the possibility of parameterizing 3-PG with ANNs or any machine learning technique may contribute to the broader use of this process-based model. In addition, artificial neural networks have great potential to assist in the calibration process of the 3-PG model, making this process more efficient by integrating environmental conditions and allowing the association between parameters. It is recommended to apply these ANNs for the conditions tested here. [Display omitted] [ABSTRACT FROM AUTHOR]

Mulching is an effective post-fire soil erosion mitigation treatment. Experiments with forest residue mulch have demonstrated that it increased ground cover to 70% and reduced runoff and soil loss at small spatial scales and for short post-fire periods. However, no studies have systematically assessed the joint effects of scale, time since burning, and mulching on runoff, soil loss, and organic matter loss. The objective of this study was to evaluate the effects of scale and forest residue mulch using 0.25 m 2 micro-plots and 100 m 2 slope-scale plots in a burnt eucalypt plantation in central Portugal. We assessed the underlying processes involved in the post-fire hydrologic and erosive responses, particularly the effects of soil moisture and soil water repellency. Runoff amount in the micro-plots was more than ten-fold the runoff in the larger slope-scale plots in the first year and decreased to eight-fold in the third post-fire year. Soil losses in the micro-plots were initially about twice the values in the slope-scale plots and this ratio increased over time. The mulch greatly reduced the cumulative soil loss measured in the untreated slope-scale plots (616 g m − 2 ) by 91% during the five post-fire years. The implications are that applying forest residue mulch immediately after a wildfire can reduce soil losses at spatial scales of interest to land managers throughout the expected post-fire window of disturbance, and that mulching resulted in a substantial relative gain in soil organic matter. [ABSTRACT FROM AUTHOR]

Declining forest health can affect crucial ecosystem functions, such as carbon storage in biomass and soils, the regulation of water regimes, the modulation of regional climate and conservation of biodiversity. Airborne laser scanning (ALS) and imaging spectroscopy (IS) are two potentially complementary remote sensing technologies capable of characterizing and monitoring regional forest health. However, the combined use of ALS and IS data to classify the health of individual trees has not yet been assessed. In this study we propose a new approach utilizing ALS and IS combined to characterize the health of individual trees. Firstly, we applied a recently developed bottom-up individual tree delineation algorithm across a structurally complex floodplain eucalypt forest that has experienced episodes of severe dieback over the past six decades. We further calculated ALS and IS indices for delineated tree crowns and used them as predictor variables in machine learning models. We trained and evaluated an object-oriented random forest classifier against field-measured tree crown dieback and transparency ratios, as indicators of eucalypt tree health and crown density, respectively. Our results showed that dieback levels of individual trees can be classified using ALS and IS with an overall accuracy of 81% and a kappa score of 0.66, while the classification of tree crown transparency levels had an overall accuracy of 70% and a kappa score of 0.5. Returned pulse width, intensity and density related ALS indices were the most important predictors in the tree health classification, as they accounted for > 40% of the variance in the data. At the forest level in terms of dieback, 81.5% of correctly delineated trees were classified as healthy, 12.3% as declining and 6.2% as dying or dead. Dieback occurred primarily in areas that were flooded < 5% of the time, as quantified by Landsat derived flooding frequency (1986–2011). Our results provide a novel application of ALS and IS to accurately classify the health of individual trees in a structurally complex eucalypt forest, enabling us to prioritize areas for forest health promotion and conservation of biodiversity. [ABSTRACT FROM AUTHOR]

• Increased exposure to canopy fire may threaten carbon stocks in resprouting forests. • The response of carbon to short-interval understorey and canopy fire was assessed. • Carbon decreased after one canopy fire but was resistant to repeated canopy fires. • Large trees are a fire-resistant carbon pool in forests of epicormic resprouters. • Carbon estimates need to account for the partial mortality of resprouting trees. Short-interval high severity wildfires threaten the stability of carbon stocks across forest communities, particularly those dominated by 'fire-sensitive' trees. However, there is a dearth of research on the effect of these extreme fires on forests dominated by 'fire-tolerant' tree species that can resprout from their trunk and branches i.e. epicormic resprouters. We assessed the effect of the severity of two wildfires occurring in short succession (6-year interval) on live and dead above ground carbon stocks (≥2.5 cm diameter) and carbon stability (i.e. the proportion of total carbon stored in live trees) in a temperate eucalypt forest dominated by epicormic resprouters. Four factorial combinations of low severity understorey fire and high severity canopy fire were examined across two wildfires. Carbon stocks were estimated using two approaches, a standard approach that assigns trees to the live and dead pools based on the presence of live foliage, and a novel approach that accounts for partial mortality of branches and stems. When accounting for partial tree mortality, total carbon stocks were greatest following repeated understorey fire and lowest in areas that had recently experienced canopy fire irrespective of canopy fire frequency. Trends in total carbon were driven by substantial reductions in live carbon following canopy fire, which were partially offset by gains in the standing dead carbon pool. Exposure to canopy fire reduced the proportion of carbon stored in live trees, increasing the susceptibility of carbon stocks to future losses through decomposition and consumption by fire. Relative to sites recently exposed to a single canopy fire, exposure to repeated canopy fires did not result in further reductions to carbon stocks or their stability. The standard carbon estimates substantially overestimated live carbon (+59 %) and underestimated dead carbon (-52 %) in areas recently affected by canopy fire, thus underestimating the impact of high severity fires on carbon stability. Our results suggest that carbon stocks in forests dominated by epicormic resprouters are sensitive to losses following canopy fire but are resistant to compounding effects of short-interval high severity fires, owing to the survival of large live stems. Our results highlight the need to account for partial tree mortality and feedbacks between short-interval wildfires when estimating transitions between carbon pools in fire tolerant forests. [ABSTRACT FROM AUTHOR]

Single-pass cut-and-chipping with modified foragers currently represents the most efficient technique for harvesting fuel chips from short rotation forestry (SRF). Modified foragers are designed to produce small chips, in the 25–30-mm length range. However, chip length settings can be adjusted for obtaining different commercial products. In that regard, it is important to determine the trade-offs of chip length manipulation, which may affect machine performance. This study tested the same modified forager designed for producing 30-mm chips, under variable chip length settings. In particular, chip length setting was adjusted both downwards to a minimum length of 5 mm (microchips), and upwards to a maximum length of 90 mm (billets). As expected, any setting adjustments that deviated from optimum values resulted in performance decline. Downward alterations of chip length setting resulted in a steady performance decline, which peaked at the shortest length setting (5 mm). Under that setting, productivity was 56% lower and diesel fuel consumption was 183% higher than under the optimum 30-mm setting. In contrast, upward alterations of chip length setting resulted in an immediate and moderate decay of machine performance at the very first increment, followed by the absence of further significant decline as additional increments were introduced. Reducing target chip length below 30 mm doubled or even quadrupled the proportion of fine particles (<3 mm) in the total chip mass, which detracted from chip quality. [ABSTRACT FROM AUTHOR]

Eucalyptus polybractea (blue mallee) is the most widely harvested species in Australia for the production of pharmaceutical grade eucalyptus oil. Its use for both oil and biomass production is set to expand because blue mallee grows vigorously on semi-arid land where agricultural crop production is unsustainable. One of the most important tools for improvement of blue mallee, and for dissection of its unique traits, is an efficient method of indirect organogenesis. Our aim was to develop such a method, which is efficient for all genotypes and applicable to adult-derived explants. We also aimed to test whether genetically modified plants could be produced using this protocol. In vitro cultures were developed from three field-grown adult clones and it was found that over 95% of the resultant leaf explants initiated callus in a medium supplemented with thidiazuron and 1-naphthaleneacetic acid. The effect of the cytokinins, 6-benzylaminopurine (BA) and N 6 -(2-isopentenyl) adenine (2iP) on plant regeneration from the initiated callus was compared. Ninety percent of callus from all three clones regenerated shoots in a medium supplemented with BA, whereas only one clone regenerated shoots at high efficiency (93%) with 2iP. Roots were successfully developed on regenerated shoots with high efficiency (>60%) via exposure to indole-3-butyric acid, and hardened plants were successfully established in soil. Leaf explants from one clone were transformed with Agrobacterium tumefaciens T-DNA containing genes for hygromycin phosphotransferase (Hpt) resistance and green fluorescent protein (GFP), both constitutively expressed using the CaMV35S promoter. Transformants showed GFP fluorescence in calli and plantlet leaves and were successfully rooted and hardened into plants. This work will enable large scale cloning of adult blue mallee plants and, after optimization of the transformation protocol, provide an important platform for further research on the biosynthesis of eucalyptus oils with the potential to dramatically improve blue mallee as a crop. [ABSTRACT FROM AUTHOR]

Although pioneer studies showed several decades ago that deep rooting is common in tropical forests, direct measurements of fine root distributions over the entire soil profile explored by the roots are still scarce. Our study aimed to compare, 2 years after planting, fine root traits of Eucalyptus trees planted from cuttings and from seedlings in order to assess whether the propagation mode has an influence on the capacity of the trees to explore very deep soils. Soils cores were sampled down to a depth of 13.5 m at the peak of leaf area index (LAI), 2 years after planting, under three Eucalyptus clones (belonging to species E. saligna , E. grandis × E. urophylla , E. grandis × E. camaldulensis ) and under E. grandis seedlings in the same Ferralsol soil. LAI was estimated using allometric equations based on destructive sampling of eight trees per genotype. All the genotypes exhibited fine root densities roughly constant between the depths of 0.25 and 6.00 m. Changes in fine root traits (diameter, specific root length and specific root area) were low between the topsoil and the root front. The ratios between mean tree height and root front depth ranged from 0.8 to 1.2 for the four genotypes. Although tree vertical extension was roughly symmetric above and belowground for all the genotypes, the depth of the root front ranged from 8.0 m for the seedlings and the E. grandis × E. urophylla clone to 11.5 m for the E. saligna clone. Soil water content profiles suggested that the four genotypes had the capacity to withdraw water down to a depth of 8–10 m over the first 2 years after planting. Total fine root length ranged from 3.3 to 6.0 km per m 2 of soil depending on the genotype. The root area/leaf area ratio ranged from 1.3 to 3.2 and was negatively correlated with LAI across the four genotypes. This pattern suggests that the genotypes more conservative for water use (with a low LAI) invest more in fine root area relative to leaf area than genotypes adapted to wet regions (with a high LAI). The velocity of downward movement of the root front might be a relevant criterion in the last stage of the breeding programs to select clones with a fast exploration of deep soil layers in drought prone regions. [ABSTRACT FROM AUTHOR]

Adaptive strategies to improve tree water-use efficiency (WUE) are required to meet the global demand for wood in a future drier climate. A large-scale throughfall exclusion experiment was set up in Brazil to study the interaction between water status and potassium (K) or sodium (Na) availability on the ecophysiology of Eucalyptus grandis trees. This experiment focused primarily on the changes in aboveground net primary production, stand water use, phloem sap and leaf δ 13 C, net CO 2 assimilation and stomatal conductance. The correlations between these response variables were determined to gain insight into the factors controlling water-use efficiency in tropical eucalypt plantations. The intrinsic WUE in individual leaves (the ratio of net CO 2 assimilation to stomatal conductance) was estimated at a very short time scale from the leaf gas exchange. Sap flow measurements were carried out to assess the WUE for stemwood production (the ratio of wood biomass increment to stand water use). Averaged over the two water supply regimes, the stemwood biomass 3 years after planting was 173% higher in trees fertilized with K and 79% higher in trees fertilized with Na than in trees with no K and Na addition. Excluding 37% of the throughfall reduced stemwood production only for trees fertilized with K. Total canopy transpiration between 1 and 3 years after planting increased from about 750 to 1300 mm y −1 in response to K fertilization with a low influence of the water supply regime. K fertilization increased WUE for stemwood production by approx. 60% with or without throughfall exclusion. There was a strong positive correlation between phloem sap δ 13 C and short-term leaf-level intrinsic WUE. Whatever the water and nutrient supply regime, the gas exchange WUE estimates were not correlated with WUE for stemwood production. Phloem sap δ 13 C and leaf δ 13 C were therefore not valuable proxies of WUE for stemwood production. The allocation pattern in response to nutrient and water supply appeared to be a major driver of WUE for stemwood production. In areas with very deep tropical soils and annual rainfall <1500 mm, our results suggest that breeding programs selecting the eucalypt clones with the highest growth rates tend to select the genotypes with the highest water-use efficiency for wood production. [ABSTRACT FROM AUTHOR]

Balanced nutrition is fundamental to health and immunity. For herbivorous insects, nutrient-compositional shifts in host plants due to elevated atmospheric CO 2 concentrations and temperature may compromise this balance. Therefore, understanding their immune responses to such shifts is vital if we are to predict the outcomes of climate change for plant–herbivore–parasitoid and pathogen interactions. We tested the immune response of Paropsis atomaria Olivier (Coleoptera: Chrysomelidae) feeding on Eucalyptus tereticornis Sm. seedlings exposed to elevated CO 2 (640 μmol mol −1 ; C E ) and temperature (ambient plus 4 °C; T E ). Larvae were immune-challenged with a nylon monofilament in order to simulate parasitoid or pathogen attack without other effects of actual parasitism or pathology. The cellular ( in vivo melanisation) and humoral ( in vitro phenoloxidase PO activity) immune responses were assessed, and linked to changes in leaf chemistry. C E reduced foliar nitrogen (N) concentrations and increased C:N ratios and concentrations of total phenolics. The humoral response was reduced at C E . PO activity and haemolymph protein concentrations decreased at C E , while haemolymph protein concentrations were positively correlated with foliar N concentrations. However, the cellular response increased at C E and this was not correlated with any foliar traits. Immune parameters were not impacted by T E . Our study revealed that opposite cellular and humoral immune responses occurred as a result of plant-mediated effects at C E . In contrast, elevated temperatures within the tested range had minimal impact on immune responses. These complex interactions may alter the outcomes of parasitoid and pathogen attack in future climates. [ABSTRACT FROM AUTHOR]

This study presents an improved theoretical formulation of the gap probability ( Pgap ) model, typically applied to indirectly estimate LAI in woody ecosystems. Specifically, we present the woody element projection function ( G W ), which characterises the angular contribution of non-leaf facets in woody ecosystems, and explain how it may be used to improve the accuracy of indirect LAI retrieval via the application of the Pgap model. G W enables separate treatment of the leaf and wood projection functions in the theoretical model, important in the typical case when Pgap includes the influence of both leaf and wood canopy elements. This study then validates the improved theoretical model using experimental data. Here, Pgap was calculated from a 3D scattering model, parameterised with highly-detailed 3D explicit tree models reconstructed from empirical data of a sampled forest stand. The experimental data was then used to quantify additional effects of view zenith angle ( VZA ), leaf angle distribution (LAD), and the influence of woody components on the indirect estimation of LAI and within-crown clumping via application of the Pgap model. Additionally, we quantify within-crown clumping of reconstructed tree models for leaf and woody elements both together and separately for the first time. LAI errors up to 25% at zenith were found when ignoring G W and were shown to be a function of VZA . Conversely, at the approximate 57.3° (1 radian) VZA , results show that there was no effect of G W due to the wood projection function converging with leaf projection functions. Within-crown clumping factors for the modelled dataset were as low as 0.35. Consequently, making a common assumption of a random distribution of canopy elements at the crown scale would lead to an LAI error of up to 65% for the 3D forest stand. We also conclude that when estimating LAI via the Pgap model, separate treatment of canopy material projection ‘ G ’ functions are required at VZA’s other than 1 radian. The findings of this study and the extended physical formulation presented here impact upon indirect Pgap LAI retrieval methods from sensors of all platforms in clumped canopy environments or canopies with woody (non-leaf) elements contributing to the extinction of light. [ABSTRACT FROM AUTHOR]

• Wildfires (WF) frequency has increased along of the years in Mediterranean region. • WF runoff may comprise dangerous impacts to freshwater ecosystems. • Ashes exposure caused growth rate (GR) inhibition and changes at biochemical level. • The larger GR inhibition was observed to Lemna exposed to high severity WF ashes. • Eucalypt ashes showed be more toxic to the macrophytes, than the pine ashes. Wildfires are a social and environmental concern to the world due to their many adverse effects, including risk to the public health and security, economic damages in prevention and fight, ecosystems pollution, land usage sustainability, and biodiversity. In the Mediterranean region, these events have increased in the last years. Although several studies evaluated the impacts of the wildfires on the structure and function of the ecosystems and their communities, there is a lack of information at the biochemical level beyond the toxicological effects to the organisms. So, aiming to evaluate the potential toxic and biochemical effects of pine and eucalypt ash from high and low severity burned areas in the aquatic environments, L. minor growth, fatty acid and carbohydrate profiles were studied. Data showed that the wildfires ash from high severity burned areas are more toxic, with a higher growth inhibition than when exposed to ash from low severity burned areas. Considering the ash from low severity burned areas, eucalypt ash revealed to be more noxious to the macrophyte than pine ash. Furthermore, it was observed a decrease in the diversity and abundance of fatty acids content, comparing with the control. An opposite trend was observed in carbohydrates which increased with the organisms' exposure to almost all ash types, except in case of the organisms exposed to eucalypt ash from high severity burned areas, where carbohydrate content decreased. [ABSTRACT FROM AUTHOR]

• Soil seed banks of wet temperate forests provide a storage effect. • Fire-cued germination concentrated in ant-dispersed species. • Germination of shade-tolerant species not enhanced by fire cues. • Edaphic variability and structural complexity promote plant diversity. • Practices that generate heterogenous environments will benefit biodiversity. Our understanding of how environmental heterogeneity shapes plant community dynamics is largely based on above-ground diversity despite the importance of seed banks as reservoirs of genetic and taxonomic diversity that buffer plant populations and influence vegetation following disturbance. Using a plant functional trait approach, this study examined the importance of fire-related germination cues and environmental determinants of plant community turnover in wet forests of south-eastern Australia – forests of both high conservation value and the focus of current timber harvesting. We surveyed extant vegetation, soil seed banks, forest structure and edaphic properties across 62 sites burnt in 1939 and not subsequently affected by wildfire or logging. A total of 46 families, and 99 species were identified in extant vegetation with 43 and 126 respectively in the soil seed bank, with only 32% of species co-occurring in both species' pools. Despite historically long fire return intervals, the soil seed bank demonstrated a clear positive response to fire-related germination cues (heat in combination with smoke) that were concentrated in hard-seeded species dispersed by ants. Seeds from early successional species showed no response to fire cues, while species typical of the wetter margins of these forests were killed by high heat. The soil seed bank was dominated by species associated with early successional stages, consistent with the initial floristics model of succession. Woody species were largely restricted to extant vegetation and replacement is most likely to occur from future seed rain. Spatially structured environmental heterogeneity shaped plant turnover with the relative strength of environmental controls differing among functional types and pools of diversity. Differential response of the combined species pool relative to extant vegetation demonstrates that the soil seed bank provides a storage effect. Forest management practices that generate patchy and heterogenous environments, including the intensity of regeneration burns and density of overstorey species, will benefit biodiversity conservation through overstorey structural controls on resource availability and diversity of understorey vegetation, that is transferred to soil seed banks via tight abiotic controls and seed inputs. [ABSTRACT FROM AUTHOR]

This study aimed at the fractionation of lignin by a simple acid precipitation from hardwood and softwood Kraft black liquors to propose new value-added applications. The precipitation was made sequentially by acidification at five different pHs (9, 7, 5, 3 and 1). The different lignin fractions were analyzed in terms of yield, ash content, elemental analysis, thermal analysis, FTIR, 1 H NMR and GPC. Hardwood lignins showed distinct relative molecular mass distributions, while softwood lignins showed similar relative molecular mass distributions in the three fractions obtained at higher pHs (pH 9, 7 and 5). This simple acid precipitation was shown to be an effective method to obtain relatively high yields of lignin. Molecular characterization by FTIR (carbonyl band) indicated that hardwood lignin was most oxidized mainly in the low pH fractions (5, 3 and 1), while the softwood lignin only presented discrete oxidized products in the lowest pHs (3 and 1). Interestingly, precipitation at pH 3 produced ash-free hardwood and softwood lignin fractions, which is a valuable product for the development of better end uses. [ABSTRACT FROM AUTHOR]

Wood utilization for pulp and paper and biorefinery applications requires some kind of mechanical and/or physical–chemical pretreatment. Among the chemical treatments the alkaline ones are the most used worldwide, although acid and solvent treatments have also being used. This paper deals with eucalypt wood deconstruction with alkaline processes including soda-AQ, soda-AQ-O 2 , soda-O 2 , and kraft. The kraft process is largely used by the pulp industry and is evaluated here only to serve as a reference. The behavior of the four eucalypt clones selected in chapter 2 were investigated when submitted to the aforementioned processes regarding their screened yield, chemical demands and pulp quality at different kappa number levels (15, 35, 50, and 70). The two most promising processes (kraft and soda-AQ) were chosen for producing pulps (kappa 15 and 20) which were studied in depth (content of carbohydrates, uronic acid, hexenuronic acid, polysaccharide molecular weight, residual lignin structure, etc.), as well as their respective black liquors (heating value, solid content, elemental analysis, and lignin structure). The main findings of this work were: (1) the wood of the four different hybrid eucalypt clones behave similarly in the various alkaline deconstruction treatments; (2) the soda-AQ and Kraft were considered the most suitable processes for producing pulp on the basis of yield, chemical demands and pulp fiber integrity; (3) the soda-AQ process can potentially replace the kraft for a high degree of wood delignification (kappa number 15); (4) the alkaline processes using oxygen (soda-AQ-O 2 and soda-O 2 ) are more suitable for wood deconstruction aimed at biofuels; and (5) the soda-AQ process resulted black liquor of more suitable burning characteristics than the kraft. [ABSTRACT FROM AUTHOR]

Tree water use is a major component of the water balance in forested catchments of semi-arid areas, as more than 80% of the incoming rainfall may be used by overstory trees. Managers are unable to easily predict water use and thus water yield, for the majority of eucalypt-dominated catchments in south-east Australia, owing to the variety of dominant and co-dominant species, their distributions with respect to landform, and the lack of species- and landform-specific knowledge of the regulation of water use. Moreover, the costs incurred to quantify input variables for available complex, process-based models, generally encourage finding alternative approaches. This study tested the adequacy of using just two easily measured variables for estimating rates of tree water use, using a model derived from data-learning techniques. The inputs are (1) measured daily atmospheric demand for water and (2) potential incoming radiation derived from surface topography and solar declination. Artificial neural networks (ANNs) and genetic programming (GP) models were trained and validated using in situ observations of vapour pressure deficit (VPD) and estimates of potential solar radiation ( Q pot ), for a period of two years, at each of 10 forest stands across the high country of the states of New South Wales and Victoria. The models were tested using a random 50% of the collected data that was independent, i.e. not used in model development. Atmospheric demand was selected because it strongly affects tree water use irrespective of site and species. Potential solar radiation was selected as a proxy for radiation, because it is relatively easy to estimate for any location for which elevation data are available in digital format, and since radiation strongly controls photosynthesis (through stomatal behaviour) and thermal balance. Genetic programming resulted in models better able to predict rates of sap flux. A selected GP model was able to describe the relationship between tree sap flux, VPD, and potential radiation with good accuracy, and was used to map tree water use across the catchment. [ABSTRACT FROM AUTHOR]

This study concerned the mid-term regeneration of the woody understory vegetation of pure and mixed stands of Pinus pinaster Ait. and Eucalyptus globulus Labill. in northern and central Portugal following wildfires in 2005 and 2006. Pine and eucalypt stands are the most widespread and most fire-prone forest types in Portugal. The main aim was to investigate the importance of biogeography, topography, forest type and post-fire management operations in explaining the patterns in shrub diversity (species richness) and abundance (cover). To this end, 284 study sites in four distinct biogeographic regions were sampled 5 to 7 years following the last wildfire. At each site, the presence and cover of individual shrub species were estimated using 4 sub-plot of approximately 10 m 2 each. The entire data set was analyzed by means of GLM using a total of seven explanatory variables: biogeographic region, forest type, three types post-fire management operations (soil tillage, tree harvesting, and shrub clearance), and two topographic variables (slope angle and elevation). The GLM analysis was also done for the individual biogeographic regions. Biogeographic region and slope steepness were key factors explaining shrub species richness, albeit the role of slope angle was possibly linked to the intensity of past land use. Biogeographic region equally played a significant role in explaining the cover of all shrubs together as well as of the shrubs of Leguminosae and Cistaceae. All three types of post-fire management operations appeared to hamper the recovery of resprouters and Leguminosae, whereas just tree harvesting and shrub clearance (but not soil tillage) negatively affected the cover of seeder species. These impacts of post-fire management operations had a noticeable region-specific component, being more relevant in the less productive biogeographic regions. Also the role of forest type depended strongly on biogeographic region. It was only significant in the South Mediterranean region, where pine plantations had a higher total shrub cover as well as higher covers of seeders and Cistaceae. Possibly, however, this significant role of forest type could be due to the lower incidence of shrub clearance in the pine stands. [ABSTRACT FROM AUTHOR]

• The module for short-rotation eucalypt plantation was implemented in ECOSMOS. • The ECOSMOS-Eucalyptus module simulates growth, carbon and water cycle. • A generic calibration can make it useful for any brazilian plantation forests. Eucalypt is one of the most-planted broadleaf genera around the globe, exhibiting high yield, plasticity and growing capacity on a broad range of environments. The main objective of this study is to present the integration of a specific module for eucalypt short-rotation plantations into ECOSMOS (Ecosystem Model Simulator). Different calibrations and validations, from intensively monitored sites, experimental networks, and plots in commercial stands were performed. We calibrated all ECOSMOS model biophysical and physiological parameters for the Eucalyptus module using three micrometeorological experiments. A generic genotype was calibrated and applied to evaluate the model performance in response to contrasting environments and genotypes, on a dataset from an experimental network with high Genotype x Environment interactions. The model was applied over commercial eucalypt plantations sites, where re-calibration was necessary for four parameters of the ECOSMOS- Eucalyptus module related to leaf carbon allocation and specific leaf area, because of significant differences in genotypes and management among datasets. Results showed the consistency of the biophysical and physiological processes solved by the model, simulated energy and carbon fluxes, soil water dynamics, and growth of different plant components when compared with observations; Nash-Sutcliffe efficiency (NSE) of 0.93, 0.43 and 0.27 for net radiation, net ecosystem exchange and evapotranspiration, respectively were obtained for the validation dataset. The generic genotype calibration varied greatly in simulating the eucalypt stem growth of the 26 locations. The generic calibration can be used as reference for eucalypt plantation' areas in Brazil; however, a re-calibration is recommended for operational applications to adjust the ECOSMOS- Eucalyptus module to the management conditions, management practices and genotypes used by companies. [ABSTRACT FROM AUTHOR]

Forest residues from Eucalyptus plantations, including the belowground biomass, has become an important energy source in tropical countries. However, the belowground biomass harvesting may reduce wood productivity in the subsequent rotations due to the depletion of soil nutrients. Thus, the present study aimed to evaluate the nutritional sustainability of Eucalyptus clones' plantations grown on second rotation in different above and belowground biomass harvest scenarios. Second rotation clones were used: Eucalyptus urophylla (AEC 0144); Eucalyptus urophylla × E. grandis (H77); and Eucalyptus urophylla × E. camaldulensis (VM01) at 13.1, 12.9 and 12.0 years of age, respectively. Trees were uprooted and split into leaves, branches, bark, stemwood and belowground. Biomass production, concentration, stock, export and use efficiency of N, P, K, Ca, Mg, B, Cu, Fe, Mn and Zn were evaluated. The highest belowground biomass production occurred in the VM01 clone, while AEC 0144 clone had the highest production of stemwood biomass. Stemwood and belowground biomass fractions had the lowest nutrient concentrations. The highest concentrations of nutrients were verified in leaves, branches and bark. Stemwood and stemwood with belowground biomass harvest scenarios presented the lowest nutrient export values and highest NUE values. Our results demonstrate that woody production of belowground biomass represents a significant part of the total biomass production of Eucalyptus trees. Thus, the removal of leaves, branches and bark fractions is more harmful to the nutritional sustainability of sandy soils than the harvesting of stumps in second rotation plantations. • The use of below-ground biomass can be an alternative source of biomass. • Eucalyptus clones can be selected according to the production of below-ground biomass. • Stemwood with below-ground biomass harvest scenario showed high nutritional sustainability. • The VM01 clone can be indicated as below-ground biomass production. [ABSTRACT FROM AUTHOR]

Short-rotation plantations are extending worldwide due to the increased demand for pulp and wood. Reliable estimations of recent expansion of short-rotation plantation areas and associated land use changes are a prerequisite to assess their environmental impact on regional carbon and water cycles, and on climate. A binary classification methodology using MODerate resolution Imaging Spectroradiometer (MODIS) 16-day 250 m NDVI time series was developed and applied to classify Eucalyptus plantations across Brazil. The identification of Eucalyptus plantations specific patterns in the time series was based on the calculation of matching functions between the NDVI time series and a ~ 2 years long reference time series. Among the seven tested matching functions, the bounding envelope was the most successful. This method was robust to residual noise on the NDVI time series, and a threshold coefficient for the binary classification was adjusted using an omission-commission criteria. With this method, it was possible to detect any presence of Eucalyptus between 2003 and 2009 at monthly time-steps, including the periods of bare soils between two rotations that are typically 6–7 years long. The dates of first afforestation, of clear-cut at the end of a rotation, and of re-planting at the beginning of a new rotation were retrieved from the NDVI time series with a precision of ~ 66 days. The final almost continuous tri-dimensional map (space and time) was validated with three different datasets, from local to regional data. All three datasets gave similarly high global accuracy statistics, but a global underestimation of Eucalyptus areas compared to large scales census was observed. Discrepancies and way to improve the Eucalyptus area estimates were discussed in this study. The developed methodology could be applied to other short-rotation tree plantations. [ABSTRACT FROM AUTHOR]

Abstract: In this study, life cycle assessment (LCA) is used to assess and compare the environmental and energy profiles of three potential bioenergy production chains using different available feedstocks in Southern European countries. Two wastes, vineyard pruning and eucalypt logging residues, and a wooden energy crop, poplar, were examined in detail. The comparative LCA study showed that the use of poplar biomass for bioenergy production has a greater impact than the use of vineyard pruning and logging residues. The contribution from the poplar-cultivation-related activities considerably affected the results, as all the activities from field preparation to harvesting have been included within the system boundaries. In contrast, all the activities performed in the vineyard and forest prior to collection of the residues have not been computed in both scenarios since they have been allocated to the driving force of these stands: grapes and roundwood, respectively. The results support the idea that forest and agricultural waste would be an interesting and potential raw material for bioenergy purposes. However, further analysis should focus on these potential bioenergy sources, namely in terms of their availability and technical burning conditions, in order to meet energy requirements. Moreover, the environmental results were compared with others from literature corresponding to electricity production using alternative biomass sources and fossil fuels. In all the categories considered for comparison, environmental benefits were reported for the electricity production using a biomass source. However, these results must be carefully used since other issues – such as production costs, water availability and land use – should be considered. [Copyright &y& Elsevier]

Highlights: [•] We estimated above ground living biomass of a eucalypt forest in eastern Australia using the PPBio system. [•] The spatial arrangement of plots and the number of replicates influenced the estimate of above ground live biomass. [•] Above ground live biomass was not related to topography or soil properties. [Copyright &y& Elsevier]

• We examined the spatiotemporal drivers of live fuel moisture content (LFMC). • Models developed from pressure-volume curve data predicted seasonal LFMC. • Leaf dry mass traits predicted maximum LFMC across a large climatic gradient. • Maximum LFMC was correlated with aridity, with lower values in arid sites. • Including leaf traits in LFMC models is likely to improve their performance. Large forest fires generally occur when the moisture content of fuels is low. For live fuels, our understanding of the physiological basis of variation in moisture content has recently advanced. However, process-based models of live fuel moisture content (LFMC) remain elusive. Here, we aim to further our understanding of the role of physiological mechanisms and plant functional traits in driving spatiotemporal variations in LFMC. We examined whether temporal variation in LFMC could be predicted from pressure-volume curve data, which measures leaf water potential and water content on cut shoots dehydrating on a bench. We also examined whether leaf dry mass traits could predict spatial variation in maximum LFMC. We undertook our study in eucalypt forests and woodlands spanning a large climatic gradient in eastern Australia. We found that LFMC models developed from pressure-volume curves reliably predicted seasonal variation in LFMC across four co-occurring species. A two-phase LFMC model, which fit models above and below the turgor loss point (mean absolute error = 3.7-33.2%), performed similarly well to a simple linear model (mean absolute error = 3.4-35.3%). Across a large climatic gradient, the maximum LFMC of 16 species was correlated with specific leaf area (R 2 = 0.54), with the exception of one species with terete terminal stems. Maximum LFMC was highly correlated with aridity (R 2 = 0.82), with lower LFMC observed in more arid sites. Our study demonstrates that spatiotemporal dynamics of LFMC are governed by both leaf dry mass traits and the relationship between leaf water potential and water content, which in turn is determined by traits such as cell wall elasticity. Thus, incorporating these traits into models of LFMC, whether these models are based on drought indices, soil moisture, or remotely sensed imagery, is likely to improve overall model performance, and subsequently improve forecasts of wildfire danger. [ABSTRACT FROM AUTHOR]

Highlights: [•] Near infrared spectroscopy was used to identify Corymbia intersectional hybrids. [•] Fresh tissue was better than thawed tissue for hybrid identification. [•] The hybrids had higher assignment rates than the parental taxa. [•] Advanced generation hybrids had much better resolution than F1 hybrids. [•] A global model should be generated to apply the spectroscopic method in field conditions. [Copyright &y& Elsevier]

Abstract: Large differences in productivity have been observed between neighboring Eucalyptus plantations in Brazil, that cannot be explained by climate and are unlikely to be due solely to altered management practices. Current ecophysiological models used by forestry companies to simulate stand development in large plantation zones rely on empirical site fertility indices (representing water and nutrient availability) to capture this spatial variability in growth rates. We propose a model that requires no empirical assessment of site fertility to simulate stand growth over entire rotations. We applied a modified version of the G’DAY model of carbon, nitrogen and water cycling at a daily time step to short-rotation plantations located in São Paulo State, including a simple mechanistic description of the effect of water availability on growth. The progressive and rapid root exploration of deep soil layers was modeled in a simple way, by considering that maximum plant available water increased with mean tree height. The model was parameterized using detailed measurements made over the entire rotation of an experimental stand of Eucalyptus grandis, and was subsequently applied to 16 clonal stands managed in a similar way by one company, but with different planting dates and contrasting productivity levels. Stem biomass simulations, driven by daily weather data (maximum and minimum air temperatures, global radiation and rainfall), were strongly correlated with company inventory estimates of stem biomass carried out at different ages. The temporal variation of leaf area index was also adequately simulated, as was shown by comparison with leaf area index derived from satellite data. The model was able to capture more than 95% of the variability of standing stem biomass and more than 85% of the variability of stem growth measured on these stands, provided spatial differences in soil water holding capacity were taken into account. [Copyright &y& Elsevier]

Abstract: The ratio among syringyl (S) and guaiacyl (G) lignin substructures is increasingly used as criteria in the selection of Eucalyptus species to pulping processes. The S/G distribution of several Brazilian Eucalyptus species and their crossings was determined by analytical pyrolysis-GC/MS (Py-GC/MS) and alkaline nitrobenzene oxidation directly from wood fibers. The ratio varied among the Eucalyptus hybrids. In Py-GC/MS, the S/G ratio is calculated by summing up the proportions of S and G type lignin pyrolysis products with various 1–3 carbon containing side chain structures. Py-GC/MS revealed that the distribution of the lignin side chain structures varied among the species. Similar trends were seen both in the G and in the S series. The result was verified with principal component analysis (PCA), which also revealed that similar side chains structures in the G and S units are correlated with each other. That PCA result confirmed that all G and S type degradation products should be included in the calculation of S/G ratios instead of selected products. S/G ratios determined by Py-GC/MS and alkaline nitrobenzene oxidation were close to each other, but not equal. Lower values were obtained by Py-GC/MS. The differences between the two methods are probably related the degradation mechanism of lignin with Py-GC/MS and nitrobenzene oxidation methods. Based on these results, it is not possible to say which of the methods is more reliable. However, both methods can well be used to compare the S/G ratios of lignin among samples. [Copyright &y& Elsevier]

Abstract: Understanding the light absorption and light use efficiency of each species at the tree scale is essential to disentangle the effects of intra- and inter-species interactions on productivity in mixed-species forest plantations. A complete randomized block design was set up using Eucalyptus grandis (E) and Acacia mangium (A), which is a N2-fixing species, planted in monospecific stands (100A, 100E) and in additive (25A:100E, 50A:100E, 100A:100E) and replacement (50A:50E) mixtures. Tree size and biomass were monitored over the complete rotation (6years). The absorbed photosynthetically active radiation (APAR) for each tree in the experiment was simulated over the full rotation with the MAESTRA model. Measurements of tree leaf area, leaf angle distributions, leaf area density, and leaf and soil optical properties were performed to parameterize this model. The APAR and the ratio of stem biomass increment divided by the APAR (which is a measure of the Light Use Efficiency [LUE] for stem production) were calculated at tree and plot scales for each year of the rotation. The LUE of the 100E stand increased with age until stabilizing at 4years of age, while the LUE of the 100A stand decreased between 2 and 4years of age and increased between the two last years of the rotation. Eucalyptus trees dominated Acacia trees in mixed plantations. The stratification of the canopy led to an increase of stand Leaf Area Index (LAI) and APAR compared to monospecific plantations. However, both Eucalyptus and Acacia LUE decreased at the end of the rotation in the mixed-species stands, with the decrease occurring more markedly in Acacia, and the final stem biomass of the stand was not enhanced in mixed-species plantations compared with the average of the pure stands. Our results indicate that a stratified canopy may offer the potential benefit of capturing more light in mixed-species forests, but this may be negated if another resource deficiency prevents trees from converting intercepted radiation into dry matter. Mixed-species plantations should be established at sufficiently rainfed sites to maximize LUE, and appropriate fertilizer regimes should be applied. [Copyright &y& Elsevier]

Abstract: The effectiveness of pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) as a rapid analytical technique to get insight in wildfire-induced molecular alterations of the soil organic matter in Mediterranean Leptosols was examined. To this end, the topsoil of two slopes with adjacent patches of burnt and unburnt Maritime Pine (Pinus pinaster) and eucalypt plantations (Eucalyptus globulus) were sampled in the Serra de Lousã, central Portugal. Several differences were found between the neighbouring burnt and unburnt soils, both in thermal desorption and pyrolysis behaviour. Thermal desorption results showed large amounts of aliphatic compounds (both alkyl and carbohydrate-derived compounds), which may indicate the incorporation of fresh plant material or low wildfire severity. Pyrolysis at 500°C revealed an increase of low molecular weight molecules for certain homologous series in fire-affected soils, suggesting the occurrence of thermal breakdown and cracking of long-chain components. In addition, the presence of several thermo-labile markers pointed to the low severity of the wildfire. Elemental analysis indicated marked fire-induced increases in TOC and TN for the pine stand as opposed to noticeable decreases for the eucalypt stands. Probably, this contrast between the two sites is not due to differences in direct fire effects (especially fire severity) but to indirect fire effects i.e. in particular needle/leaf fall from affected canopies. [Copyright &y& Elsevier]

Abstract: This study evaluates the environmental impacts associated with the production of eucalypt (Eucalyptus globulus Labill.) and maritime pine (Pinus pinaster Ait.) wood in Portugal. Life Cycle Assessment (LCA) methodology is used from cradle-to-gate. Three forest management scenarios, representative of different forest management intensities and logging equipment, were simulated for each species. Furthermore, a sensitivity analysis was performed to evaluate the influence of adopting different values for the wood productivity. The results obtained for each impact category show a relatively wide range of variation when different management scenarios and wood productivities are taken into account. The impacts, except for those in the category photochemical oxidant formation, are much smaller in the less intensive scenario (40–88%). The impacts of using chainsaws and adapted farm tractors in logging operations instead of harvesters and forwarders do not significantly differ (less than 11%), except for the impact category photochemical oxidant formation for which there are significant differences. For the same type of management scenario, the impacts of eucalypt wood production are larger than those estimated for maritime pine wood. The logging stage, as well as fertilization, especially with nitrogen-containing fertilizers, plays a major role in all the impact categories. More accurate impacts could be quantified using the methodology adopted in this study when the provenance of the wood and, consequently, the forest operation type and frequency, and associated consumption of fuels, lubricants and fertilizers, are known. [Copyright &y& Elsevier]

Abstract: Their fast growth and adaptability make hardwoods good candidates for bioethanol production. This study evaluated acacia and eucalypt for bioethanol production in Taiwan. Enzyme formulations with endoglucanase, cellobiohydrolases and xylanase activities were applied for subsequent saccharification. The hydrolysis efficiencies were negatively impacted by the lignin contents of pulps. SSF (Simultaneous saccharification and fermentation) were also conducted using Saccharomyces cerevisiae D5A. After 170 h, 70.72 and 65.21 g of ethanol (per kg oven-dried wood) were produced from acidic exploded acacia and eucalypt pulps, respectively. In addition, 44.50 and 42.27 g of ethanol (per kg oven-dried wood) were produced from unbleached acacia and eucalypt kraft pulps, respectively. The overall potential of bioethanol production from the hardwoods in Taiwan was also estimated. [Copyright &y& Elsevier]

Abstract: The morphological and chemical characteristics of the woods from several eucalypt hybrids from the Brazilian Genolyptus program were studied. The hybrids selected for this study were Eucalyptus grandis × E. urophylla (IP), E. urophylla × E. urophylla (U1×U2), E. grandis ×[E. urophylla × E. globulus] (G1×UGL), and [E. dunnii × E. grandis]× E. urophylla (DG×U2). The analyses of the lipophilic extractives indicated a similar composition in all eucalypt hybrids, which were dominated by sitosterol, sitosterol esters and sitosteryl 3β-d-glucopyranoside. These compounds are responsible for pitch deposition during kraft pulping of eucalypt wood. Some quantitative differences were found in the abundances of different lipid classes, the wood from U1×U2 having the lowest amounts of these pitch-forming compounds. The chemical composition and structure of lignins were characterized by Py-GC/MS and 2D-NMR that confirmed the predominance of syringyl over guaiacyl units and only showed traces of p-hydroxyphenyl units in all the woods, with the highest S/G ratio for G1×UGL. The 2D-NMR spectra gave additional information about the inter-unit linkages in the lignin polymer. All the lignins showed a predominance of β-O-4′ ether linkages (75–79% of total side-chains), followed by β–β′ resinol-type linkages (9–11%) and lower amounts of β-5′ phenylcoumaran-type, β-1′ spirodienone-type linkages or β-1′ open substructures. The lignin from the hybrid G1×UGL presented also the highest proportion of β-O-4′ linkages, and therefore, it is foreseen that the wood from this hybrid will be more easily delignifiable than the other selected Brazilian eucalypt hybrids. In complement to these chemical analyses, the morphological characterization of fibers, vessels and fines revealed that hybrid eucalypt clone DG×U2 presented the most interesting properties for the manufacture of paper pulps and biofuels. [Copyright &y& Elsevier]

Abstract: The cyanogenic glucoside profile of Eucalyptus camphora was investigated in the course of plant ontogeny. In addition to amygdalin, three phenylalanine-derived cyanogenic diglucosides characterized by unique linkage positions between the two glucose moieties were identified in E. camphora tissues. This is the first time that multiple cyanogenic diglucosides have been shown to co-occur in any plant species. Two of these cyanogenic glucosides have not previously been reported and are named eucalyptosin B and eucalyptosin C. Quantitative and qualitative differences in total cyanogenic glucoside content were observed across different stages of whole plant and tissue ontogeny, as well as within different tissue types. Seedlings of E. camphora produce only the cyanogenic monoglucoside prunasin, and genetically based variation was observed in the age at which seedlings initiate prunasin biosynthesis. Once initiated, total cyanogenic glucoside concentration increased throughout plant ontogeny with cyanogenic diglucoside production initiated in saplings and reaching a maximum in flower buds of adult trees. The role of multiple cyanogenic glucosides in E. camphora is unknown, but may include enhanced plant defense and/or a primary role in nitrogen storage and transport. [Copyright &y& Elsevier]

After presenting a short review of process-based model requirements to capture the plant dynamic response to defoliation, this paper describes the development and testing of a model of crown damage and defoliation for Eucalyptus. A model that calculates light interception and photosynthetic production for canopies that vary spatially and temporally in leaf area and photosynthetic properties is linked to the forest growth model CABALA. The process of photosynthetic up-regulation following defoliation is modelled with a simple conditional switch that triggers up-regulation when foliar damage or removal causes the ratio of functional leaf area to living tissue in the tree to change. We show that the model predicts satisfactorily when validated with trees of Eucalyptus nitens and Eucalyptus globulus from a range of sites of different ages, subject to different types of stress and different types of defoliation events (R 2 =0.96 across a range of sites). However, the complexity of particular situations can cause the model to fail (e.g. very heavy defoliation events where branch death occurs). It is concluded that while the model will not cope with all situations, an appropriate level of generality has been captured to represent many of the physiological processes and feedbacks that occur following defoliation or leaf damage. This makes the model useful for guiding management interventions following pest attack and allows the development of scenarios including climate change impact analyses and decision-making on the merits of post-defoliation fertilisation to expedite recovery. [Copyright &y& Elsevier]

Abstract: Wood properties are ultimately related to the morphology and biophysical properties of the xylem cell wall. Although the cellulose and lignin biosynthetic pathways have been extensively studied, modifications of other wall matrix components during secondary growth have attracted relatively less attention. In this work, thirty-eight new Eucalyptus cDNAs encoding cell wall-modifying proteins from nine candidate families that act on the cellulose–hemicellulose and pectin networks were cloned and their gene expression was investigated throughout the developing stem. Semi-quantitative RT-PCR revealed distinct, gene-specific transcription patterns for each clone, allowing the identification of genes up-regulated in xylem or phloem of stem regions undergoing secondary growth. Some genes, namely an endo-1,4-beta-glucanase, one mannan-hydrolase and three pectin methylesterases showed transcription in juvenile and also in mature stages of wood development. The patterns of gene expression using samples from tension and opposite wood disclosed a general trend for up-regulation in tension wood and/or down-regulation in opposite wood. Localised gene expression of two selected representative clones, EGl-XTH1 and EGl-XTH4, obtained through in situ hybridization confirms the RT-PCR results and association with secondary xylem formation. Likewise, immunolocalisation studies with the anti-pectin antibody (JIM5) also supported the idea that the development of tissue-specific pectin characteristics is important during secondary growth. These results emphasize an involvement of hemicellulose and pectin biochemistry in wood formation, suggesting that the controlled and localised modification of these polysaccharides may define cell properties and architecture and thus, contribute to determining different biophysical characteristics of Eucalyptus wood. [Copyright &y& Elsevier]

Abstract: This study was carried out to explore the possibility of making cement-bonded wood–wool composite building products using eucalypt (Eucalyptus camaldulensis) and poplar (Populus deltoides). The experimental design consisted of three treatments – ratio of wood–wool mixture, percentage concentration of cement, and calcium chloride (CaCl2). The mechanical properties in terms of modulus of rupture (MOR), modulus of elasticity (MOE) and internal bond (IB) strength were investigated. The ratios of wood–wool to cement were 40:60 and 60:40 by weight. The addition of the woody material to cement clearly reduced the maximum hydration temperature and increased the time to maximum temperature. Eucalypt was generally less compatible with cement than poplar wood. Test results showed that boards made with poplar wood–wools had superior properties compared to the eucalypt and mixed wood–wools. The presence of eucalypt in mixture of woody materials typically resulted in decrease in mechanical properties. It has been noted that a dose of 5% of CaCl2 by weight of cement can enhance the effect of cement. Application of Duncan''s Multiple Range Test for the mean values of the results showed that the effects of all variables and their interactions on the mechanical properties in terms of MOR, MOE and IB were highly significant (p ≤0.01%). The mechanical properties of most produced boards were found to satisfy the minimum requirements of ISO standard. [Copyright &y& Elsevier]