Biomass accumulation in rapidly growing loblolly pine and sweetgum

Loblolly pine (Pinus taeda) and sweetgum (Liquidambar styraciflua) trees, growing in International Paper Company's study of intensive management on marginal agricultural land near Bainbridge GA, were destructively sampled at the end of the sixth growing season. All trees were single family blocks of genetically superior trees planted 2.5 m apart on sub-soiled rows 3.6 m apart and grown with complete competition control. Management treatments were: control, irrigation, irrigation plus fertilization, and irrigation plus fertilization plus pest control. Tree measures were basal diameter, DBH, height of live crown, diameter at base of live crown, and total height. Twenty trees of each species were destructively sampled. Stems were sectioned at 1 m intervals, stem diameter determined at each end and sections were weighed green. Branches were removed and height, basal diameter, and length were measured on each branch. Branches were separated into foliated and unfoliated segments and weighed green. A stem disk and branch from each meter were returned to the lab to determine dry weight: green weight ratio. Foliated limb: foliage ratios were also determined from sub-sampled branches. Intensive culture resulted in larger growth differences for sweetgum (most intensive treatment 9.5 m tall, 13.1 cm DBH; control trees 5.0 m tall, 6.3 cm DBH) than in pine (most intensive treatment 10.3 m tall, 17.7 cm DBH; control, 7.6 m tall, 13.4 cm DBH). The pipe model of tree development explained dimensions of the upper 5 m of crown with leaf biomass highly correlated to branch basal area (r² from 0.697 to 0.947). There was a constant ratio of leaf biomass to branch basal area (50 gm/cm² for pine, 30 gm/cm² for sweetgum). We also found a constant ratio of bole basal area to cumulative branch basal area throughout the crowns. Rapidly growing pines produced about 49 Mg ha⁻¹ of stem biomass, 11 Mg ha⁻¹ of dead branch biomass, and 17 Mg ha⁻¹ of unfoliated branch biomass at the end of six years.     

Estimating biomass of individual pine trees using airborne lidar

Airborne lidar (Light Detection And Ranging) is a proven technology that can be used to accurately assess aboveground forest biomass and bio-energy feedstocks. The overall goal of this study was to develop a method for assessing aboveground biomass and component biomass for individual trees using airborne lidar data in forest settings typical for loblolly pine stands (Pinus taeda L.) in the southeastern United States. More specific objectives included: (1) assessing the accuracy of estimating diameter at breast height (dbh) for individual pine trees using lidar-derived individual tree measurements, such as tree height and crown diameter, and (2) investigating the use of lidar-derived individual tree measurements with linear and nonlinear regression to estimate per tree aboveground biomass. In addition, the study presents a method for estimating the biomass of individual tree components, such as foliage, coarse roots, stem bark, and stem wood, as derived quantities from the aboveground biomass prediction. A lidar software application, TreeVaW, was used to extract forest inventory parameters at individual tree level from a lidar-derived canopy height model. Lidar-measured parameters at individual tree level, such as height and crown diameter, were used with regression models to estimate dbh, aboveground tree biomass, and tree-component biomass. Field measurements were collected for 45 loblolly pine trees over 0.1- and 0.01-acre plots. Linear regression models were able to explain 93% of the variability associated with individual tree biomass, 90% for dbh, and 79–80% for components biomass.     

Comparison of biomass and nutrient content equations for successive rotations of loblolly pine plantations on an Upper Coastal Plain Site

This study compared first- and second-rotation biomass and nutrient equations between successive loblolly pine plantations on an Upper Coastal Plain Site in Alabama. Nutrient concentration relationships with crown position were explored in order to evaluate their significance for biomass studies determinations. Trees were destructively sampled from across the diameter distribution of the stand for each rotation. Tissues were separated into foliage, branch, stemwood, and stembark and analyzed for nutrient concentration and dry weight. Distance from the top of the tree was recorded for all tissues of the selected second-rotation trees and plotted against nutrient concentrations. Regression equations for individual tree tissue biomass and nutrient content were fit for each rotation and compared. Analyses of nutrient concentration relationships with crown position indicated that mobile nutrient (N, P, K, Mg, S, and Zn) concentrations of stemwood, bark, and branches decreased with distance from the top of the tree and height of the live crown. Foliar nutrient concentrations and non-mobile nutrients (Ca and B) for other tissues showed no patterns with tree height. Stemwood biomass regression equations were equivalent after two rotations. However, biomass and nutrient content regression equations for foliage, branches, and bark differed between rotations. Major differences between rotations were in stemwood N and P, and foliage, branch and bark B concentrations, which suggested reduced availability of these nutrients in the second-rotation stand.     

Some metals in aboveground biomass of Scots pine in Lithuania

The stocks of iron (Fe), manganese (Mn), zinc (Zn) and aluminium (Al) in different compartments of the aboveground tree biomass were estimated in Scots pine (Pinus sylvestris L.) stands in Lithuania. Simulated removals of metals due to the forest biomass extraction in a model Scots pine stands during a 100-year-long rotation period were compared with metals pools in sandy soil and the fluxes through atmospheric deposition. Applying whole tree harvesting, total removal comprised about 20 kg ha⁻¹ of each Al and Mn, and 5 times lower amount of each Zn and Fe. The metals were mainly removed with stemwood and living branches. However, metal export with aboveground biomass represented relatively small proportion of metals in mineral sandy soil. The annual inputs of Fe and Zn with atmospheric deposition were over 10 times higher than the mean annual removals with total aboveground biomass. The content of metals in forest biomass fuel ash was relatively small to compare with their total removals. The findings of this study have an important implications for future practice, i.e. the recommended maximum forest biomass fuel ash dose for the compensating fertilising could be increased with respect to balanced output – input in Lithuania.     

Above-ground biomass production and allometric relations of Eucalyptus globulus Labill. coppice plantations along a chronosequence in the central highlands of Ethiopia

Eucalyptus plantations are extensively managed for wood production in the central highlands of Ethiopia. Nevertheless, little is known about their biomass (dry matter) production, partitioning and dynamics over time. Data from 10 different Eucalyptus globulus stands, with a plantation age ranging from 11 to 60 years and with a coppice-shoot age ranging from 1 to 9 years were collected and analyzed. Above-ground tree biomass of 7–10 sampled trees per stand was determined destructively. Dry weights of tree components (W_c; leaves, twigs, branches, stembark, and stemwood) and total above-ground biomass (W_a) were estimated as a function of diameter above stump (D), tree height (H) and a combination of these. The best fits were obtained, using combinations of D and H. When only one explanatory variable was used, D performed better than H. Total above-ground biomass was linearly related to coppice-shoot age. In contrast a negative relation was observed between the above-ground biomass production and total plantation age (number of cutting cycles). Total above-ground biomass increased from 11 t ha^?1 at a stand age of 1 year to 153 t ha^?1 at 9 years. The highest dry weight was allocated to stemwood and decreased in the following order: stemwood > leaves > stembark > twigs > branches. The equations developed in this study to estimate biomass components can be applied to other Eucalyptus plantations under the assumption that the populations being studied are similar with regard to density and tree size to those for which the relationships were developed.     

Effects of wood ash and nitrogen fertilization on Scots pine crown biomass

The crown biomass, being one of the most susceptible components of the above-ground tree biomass, could respond positively to environmental changes and temporary increase in nutrient availability. The influence of wood ash and nitrogen fertilization on crown biomass was studied in a 40-year-old Scots pine (Pinus sylvestris L.) stand growing on a Haplic Arenosol. The 36-model trees for the crown biomass measurements were sampled for 3 growing seasons after the application of 5.0 t wood ash ha⁻¹, 180 kg N ha⁻¹, 2.5 t wood ash ha⁻¹ plus 180 kg N ha⁻¹, and control (untreated plots). The masses of the current, 1-year-old and older needles and shoots, and branches were measured. A significant influence on the current year needles and shoots was found after the application of 180 kg N ha⁻¹ or 2.5 t wood ash ha⁻¹ plus 180 kg N ha⁻¹. When wood ash was applied in combination with nitrogen, an extra response tendency of the crown growth, especially of the top and the middle sections of the crown, was determined. However, there was no short-term influence of wood ash on crown biomass growth.     

Carbon and nutrients of Scots pine stands on sandy soils in Lithuania in relation to bioenergy sustainability

Sustainable forestry is based on the principle that harvesting practices should avoid negative influence on soil fertility, wood production and long-term soil carbon (C) stocks. We examined C and nutrient concentrations and stocks of Scots pine (Pinus sylvestris L.) stands on Arenosols in south-western Lithuania. The stands were 10, 20, 40, 50 and 65 years of age. C concentrations were relatively constant, while the concentrations of N, P, K, Ca, Mg and S often varied between compartments and stand ages.The total aboveground stocks of nitrogen (N) were estimated to be in the range of 185–260 kg ha⁻¹, and 78–189 kg ha⁻¹ for calcium (Ca), 75–104 kg ha⁻¹ for potassium (K), 22–33 kg ha⁻¹ for phosphorus (P), 21–41 kg ha⁻¹ for magnesium (Mg) and 16–28 kg ha⁻¹ for sulphur (S). Corresponding stocks of the crown alone were 139–207 kg ha⁻¹ of N, 54–88 kg ha⁻¹ of Ca, 44–79 kg ha⁻¹ of K, 15–26 kg ha⁻¹ of P, 15–23 kg ha⁻¹ of Mg, and 11–15 kg ha⁻¹ of S. Biomass, C and nutrient stocks in the crown did not change with age, whereas the stemwood stocks increased with stand age. The total removals of C and N over a whole 100-year rotation were simulated to be 129 Mg ha⁻¹ and 449 kg ha⁻¹, respectively. An example scenario was created to compare the magnitude of potential nutrient removals with the atmospheric influx, soil stocks, and the internal litterfall flux. We suggest that intensified utilisation of these stands for bioenergy may be sustainable.     

Silvicultural manipulation and site effect on above and belowground biomass equations for young Pinus radiata

There is little understanding of how silvicultural treatments, during the early stages of tree development, affect allometric relationships. We developed and compared stem, branch, foliage, coarse and fine root biomass, and leaf area estimation equations, for four-year-old genetically improved radiata pine trees grown on three contrasting soil-site conditions. At each site, selected trees were destructively sampled from a control (shovel planted, no weed control, fertilized with 2 g of boron), a shovel planted + weed control (2 first years) + complete fertilization (nitrogen + phosphorus + boron 2 first years + potassium 2nd year), and a soil tillage (subsoil at 60 cm) + weed control (first 2 years) + complete fertilization treatment. Tissues were separated into foliage, branch, stem, fine and coarse roots (>2 mm). Regression equations for each tree biomass tissue versus leaf area were fit for each site and compared among treatments and sites with the same genetic material. Our results indicated that individual tree biomasses for young plantations are affected by silvicultural treatment and site growing conditions. Higher variability in estimates was found for foliage and branches due to the ephemeral nature of these components. Stem biomass equations vary less, but differences in biomass equations were found among sites and treatments. Coarse root biomass estimates were variable but less than expected, considering the gradient among sites. Similar to stem biomass, a simple positive general linear relationship between root collar diameter, or diameter at breast height with coarse roots biomass was developed across sites and treatments.     

Estimation of pruning biomass of olive trees using airborne discrete-return LiDAR data

The use of residual biomass from fruit tree pruning requires the creation of logistic schedules based on the knowledge of the amount of residues available in each plot. Remote sensing is shown as an important tool to quantify these resources. The objective of this research was to estimate the amount of pruned materials from olive trees (Olea europea L.) using dendrometric parameters obtained from field measurements and airborne LiDAR (Light Detection and Ranging) data. Pruning, mean crown diameter, stem diameter, total height and crown height were measured in the field for a set of 25 trees in Viver, Central East Spain. Airborne discrete LiDAR data were acquired and used to extract the crown area of the trees and metrics based on the height distribution of the LiDAR points. Two types of regression models to predict the amount of pruned material were computed, firstly using dendrometic measurements obtained in the field, and then based on tree metrics derived from LiDAR data. The dendrometric variables obtained from field measurements were also compared with the metrics obtained from LiDAR data. High values of R² were obtained for the models, ranging from 0.86 to 0.89. The regression models derived from LiDAR data used the area as an explanatory variable. The results of this study show the potential of airborne LiDAR data to predict pruning residues in olive trees.     

Impacts of changing the minimum diameter of roundwood on the accumulation of logging residue in first thinnings of Scots pine and Norway spruce

The aim of this study was to examine the impacts of different minimum top diameters of roundwood on the accumulation of logging residue in first thinnings of Scots pine and Norway spruce. The aim was also to compare estimates of residue accumulation calculated by tree-specific models with field measurements from thinnings. Felling experiments were performed in young pine and spruce stands to evaluate the model calculations. The felling was performed by a harvester with a single-grip harvester head. Sample trees were felled and processed to a minimum diameter of 12, 10, 8 and 6 cm and the delimbed branches and stem wood between these cutting points were weighed. The mean relative masses of the tree tops of spruce were nearly doubled with each increment of 2 cm in the top diameter. Respectively in pine, the mean relative tree top mass was increased by 50-60% when the top diameter was increased by 2 cm. The mass of total residue (tree top and all delimbed branches) was similarly increased, but the differences were not as large. Compared to pine, smaller variation in the crown mass of the spruce sample resulted in a more accurate model prediction of the mass of tree tops and total residue. The results of this study suggest that the biomass quantity and distribution of a small amount of trees cannot be predicted very reliably, but when these results are generalized to stand-level, the model predictions can be improved to a practicable level.     

Cambio-xylofauna abundance and species diversity of cutting residues in Scots pine and Norway spruce clear-cuts in Lithuania

The research was conducted at Dubrava Training Experimental Forest Enterprise, Kaunas District, Lithuania, in 2004. The aim was to estimate the abundance, species composition and diversity of cambio-xylofauna hibernating in oak, Norway spruce and Scots pine cutting residues (branches) left in spruce and pine clear-cuts. The research plots with replicates were arranged in the clear-cuts from September 2003. More than 1000 arthropods were identified in oak, spruce and pine cutting residues. The class of Insecta was represented by the orders Diptera (51%), Psocoptera (24%), Coleoptera (22%) and Hymenoptera (2%). According to the Shannon diversity index, species diversity of cambio-xylofauna hibernating in thin spruce branches (H=2.19) was significantly (p=0.001) higher than in spruce branches of medium diameter (H=1.36). The difference between species diversity in thin and thick spruce branches was unreliable (p=0.2). In oak cutting residues (branches), 7 rare (Bitoma crenata Fabr., Dissoleucas niveirostris, Fabr., Leiopus nebulosus L., Pyrochroa coccinea L., Saperda scalaris L., Sulcacis affinis Gyll., Trachodes hispidus L.) and 3 very rare (Cis hispidus Gyll., Mordella aculeata, L., Orthocis alni Gyll.) insect species, as well as 1 species new in Lithuania (Phymatodes alni L.), were identified.     

Predictive models for dry weight estimation of above and below ground biomass components of Populus deltoides in India: Development and comparative diagnosis

This article concentrates on development of statistical models for prediction of biomass components (above and below ground) of standing trees of Populus deltoides. Twenty seven trees (three each from age one to nine years) were destructively harvested, separated, sorted, sub-sampled, dried to constant weight at 60 °C and weighted for biomass components (leaf, twig, branch, bole, stump root, lateral root, fine root). Harvesting in a similar manner, was continued annually up to nine years of tree age and thus in all 27 sampled trees were available for analysis and fitting of models. Diameter at breast height (dbh) alone was a very good predictor of dry weight and accordingly the height was not included in the model. Various functions viz (linear, allometric, logistic, gompertz and chapman-richards), were attempted for dry weight estimation. The linear model, though easiest to fit, suffered from the ‘negative estimation problem’, specifically for the lower range of explanatory variate. Of the remaining non-linear models, the allometric model outperformed the others on the basis of validation criterions. The value of R² ranged from 0.95 to 0.99, for the allometric models fitted on various biomass components. The proposed models can be used for prediction of component wise dry biomass of P. deltoides for a wide range of dbh values (1-50 cm) at one end and can also help farmers in the choice of economical harvest rather than the traditional physical rotation. In addition, they can be used in carbon sequestration studies, which needs complete biomass estimation.     

Modeling stump biomass of stands using harvester measurements for adaptive energy wood procurement systems

The value and volumes of industrial stump fuel supply are increasing for energy production. Accurate estimates of aboveground and belowground biomass of trees are important when estimating the potential of stumps as a bioenergy source. In this study two stump biomass equations were adapted and tested using them as calibrated stump biomass models computed as the cumulative sum by a local stand. In addition, variables derived from stem measurements of the forest harvester data were examined to predict stump biomass of a stand by applying regression analysis. The true stump yield (dry weight) was used as the reference data in the study. Both biomass models performed well (adjusted R² ˜ 0.84) and no advance was found in using other stem dimensions as independent variables in the model. The stand-level model can be used in innovative stump biomass prediction tools for increasing efficiency of energy wood procurement planning to stands within a certain area. In practice, wood procurement managers would need to adapt developed system and decide whether the degree of accuracy/precision provided by the models is acceptable in their local stand harvesting conditions.     

Aboveground and belowground biomass allocation in native Prosopis caldenia Burkart secondaries woodlands in the semi-arid Argentinean pampas

The woodlands in the south-west of the Argentinean pampas are dominated by Prosopis Caldenia Burkart (calden). The current deforestation rate of this woodlands is 0.82% per year. Different compensation initiatives have begun that recognize the role of forests as environmental service providers. The financial incentives they offer make it necessary to quantify the amount of carbon stored in the forest biomass. A model for estimating calden biomass was developed. Thirty-eight trees were selected, felled and divided into sections. An equation system was fitted using joint generalized regression to ensure the additivity property. A weighted regression was used to avoid heteroscedasticity. In these woodlands fire is the main disturbance and it can modify tree allometry, due this all models included the area of the base of the stem and tree height as independent variables since it indirectly collects this variability. Total biomass and the stem fraction had the highest R2_Adj. values (0.75), while branches with a diameter less than 7 cm had the lowest (0.58). Tree biomass was also analyzed by partitioning into the basic fractions of stem, crown, roots, and the root/shoot ratio. Biomass allocation was greatest in the crown fraction and the mean root/shoot ratio was 0.58. The carbon stock of the caldenales considering only calden tree biomass is 20.2 Mg ha⁻¹. While the overall carbon balance of the region is negative (deforestation and biomass burning, the remnant forested area has increased their calden density and in an indirect way his carbon sequestration capacity could also be increased.     

The characteristics of whole-tree fuel stocks from silvicultural cleanings and thinnings

The fuel properties of small-sized whole-tree fuel stocks were studied in roadside and in-stand storages. The significance of pile cover, season and storage site on moisture content and heating value of Scots pine (Pinus sylvestris) and pubescent birch (Betula pubescence) fuel stocks were observed.When the fuel stocks are placed in a well-ventilated location moisture content may be lowered below the 40% mark during one summer period. Covering the piles will give up to 6% units lower moisture content in comparison with non-covered piles. The most benefit is gained from covering during snow melting in spring and the least in midwinter when the snow is dry.Multi-tree harvested stemwood with no limbs seasoned equally well as the whole trees both in roadside and in-stand trials. This is because the processing of multi-tree bunches caused some debarking to take place. As a result, the transpiration drying capability of whole trees was equalized by the evaporation of moisture via the open wood surface. Both assortments reached moisture contents below 30% in in-stand conditions during one summer's seasoning.The effective heating values of neither birch nor pine showed significant changes. However, heating value deviated with the composition of the fuel stock. The presence or absence of crown material was a factor.The microbial counts of mesophilic fungi in whole-tree fuel stocks were only 1% of that found in logging residues. The counts of thermo-tolerant fungi were still much smaller. Leaving the Scots pine piles uncovered will increase the number of mesophilic fungal spores and bacteria.     

Suitability of published biomass equations for aspen in Central Europe—Results from a case study

Published biomass equations were applied to sample trees from an 18-year-old Populus tremula (L.)×P. tremuloides (Michx.) (Astria) stand in Germany and compared with the measured dry weights. Equations originally developed for quaking aspen did not perform better than equations derived from European aspen data. The complexity of equations also did not influence the mean percent deviation of calculated dry weights from measured dry weights. Equations derived from measurements in short-rotation coppice cultures grossly overestimated weights. The accuracy of the predictions of total tree biomass changed according to the gradient in height:diameter ratio of the sample trees of the original studies. Equations from trees with similar h/d ratio as the sample trees were more accurate than others. When equations from the literature are used to estimate biomass for given stands, equations that resulted from sample trees with similar height:diameter ratios should be preferred.     

Recovery rates of logging residue harvesting in Norway spruce (Picea abies (L.) Karsten) dominated stands

A significant amount of logging residues is available for recovery in clear-cut areas. The forest residues’ potential has usually been estimated using biomass models. In Norway spruce (Picea abies) dominated stands, a large share of material is left on site especially due to dropping of needles as residues are left on site to dry in small heaps. In this study, we compared the measured dry weight of logging residues at a power plant with the potential biomass estimations made at a stand level. The study was performed in eight Norway spruce dominated stands, three of which were located in eastern Finland (North Karelia region) with the remainder being in Central Finland. The dry weights of branches, needles and stem tops were estimated using biomass models developed for individual trees by Repola et al. [1]. These dry weights were also compared with Swedish biomass models produced by Marklund [2]. The diameter and tree height information of each harvested tree served as input data in these model-based computations. Tree diameter information was obtained straight from the harvester’s stem value files, while the height information was obtained from models using the data from the stem value files as input. Inventory data before logging was used as a control material for harvester based estimates to spot possible measurement errors on the harvester measurement data. In addition, inventory data were used to get the crown height information, which was not available in the harvester measurement data. It was found that the average recovery rate was approximately 62% when applying Repola’s et al. [1] models and 61% when applying Marklund’s [2] models. However, variation between the logging sites was high. According this study, at least a third of the residues remains on the logging site if they are seasoned during the spring and summertime in small heaps.     

Switchgrass growth and morphological changes under established pine-grass agroforestry systems in the lower coastal plain of North Carolina,United States

Switchgrass (Panicum virgatum L.) intercropped with Loblolly pine (Pinus taeda L.) has been proposed as a potential biomass feedstock for biofuel production in the southeastern United States. This study investigated effects of treatments (intercropping vs. grass only) on biomass increment processes and morphological properties of switchgrass at two experimental plots (Lenoir1) located in the coastal plain of North Carolina. We also evaluated effects of trimming lower tree branches of pine trees on switchgrass growth at another watershed-scale site (Carteret7) in the same region. Results showed that biomass yield of intercropped switchgrass was reduced by adjacent trees and negatively affected by relative position of grass to trees at the 6th year after planting at Lenoir1. Relative grass-to-tree position was also found to be a significant (p < 0.001) factor affecting grass growth at Carteret7 site with tree age of 5 years old, which is irrespective to the trimming practice. Trimming lower tree branches did not significantly (p = 0.57) improve biomass yield of switchgrass at Carteret7. We also observed intercropped switchgrass typically had higher specific leaf area and grew taller compared to grass-only plots. Stem-to-leaf ratios of switchgrass were significantly (p = 0.02) affected by trees at Lenoir1, but not by trimming lower branches in Carteret7 and relative position of grass to trees at both study sites. Findings from this study are important for evaluating the viability of producing biofuel feedstocks using this proposed intercropping system in the southeastern United States.     

Available residual biomass obtained from pruning Morus alba L. trees cultivated in urban forest

Large quantity of residual biomass with possible energy and industrial end can be obtained from management operations of urban forests. The profitability of exploiting these resources is conditioned by the amount of existing biomass within urban community ecosystems. This research was focused on direct and indirect quantification of lignocellulosic waste from urban tree pruning of Morus alba, which is widely deployed as ornamental vegetation in Mediterranean countries. The mean quantity of dried pruned biomass obtained in street and park location was 31.67 kg/tree and 77.78 kg/tree with standard deviation 16.88 kg/tree and 29.51 kg/tree, respectively. Mathematical models for predicting the available amount of pruning residues for this species were developed from easily measurable dendrometric parameters, such as diameter at breast height, crown diameter and total tree height. The best functions were obtained when several variables were combined in quadratics models. R² was 0.96 for topping type of pruning practice and street location, and 0.88 in maintenance pruning applied in park areas. Good results were also found when correlating apparent crown volume with kilograms of yielded residues. These models can be used for urban inventories and the application of logistic models. The analysis indicates that an abundant amount of residual biomass originating from pruning operations of ornamental species can be used to achieve ecological and energy targets.     

Estimation of woody biomass production from a short-rotation bio-energy system in semi-arid Australia

Short, 3–5 year, rotations of trees have been proposed as a method of regaining hydrological control of dryland farming systems (300–600 mm annual rainfall) in southern Australia and thus alleviating salinization of land and water. At the termination of the rotation, the trees will be removed and used as a bioenergy feedstock. In the absence of any tree growth data in this region, allometric relationships were developed for three prospective short-rotation species (Eucalyptus globulus, Eucalyptus occidentalis and Pinus radiata), for 3-year-old trees, at a site with a mean annual rainfall of 365 mm. Equations that related stem diameter over bark at 10 cm (D₁₀) and tree height (ht) to total tree biomass (above and below ground), leaves, stems (stemwood and bark) and roots were developed, by combining data from different planting densities (500, 1000, 2000 and 4000 stem ha⁻¹) and landscape positions (upper-slope, mid-slope and lower-slope).Mean oven-dry yields of the three species, in the high planting density treatment were not significantly different and ranged from 12 to 14 t ha⁻¹ (3 years)⁻¹. There were consistent increases in biomass yield with planting density, with this generally being greatest with the 4000 stem ha⁻¹ treatment. There were marked differences in productivity with slope position. For E. globulus and E. occidentalis the best yields were obtained in lower landscape positions with initial planting densities of 4000 stem ha⁻¹, with 16.6 and 22.2 t ha⁻¹ (3 years)⁻¹, total biomass produced, respectively. The best yield of P. radiata was 15.4 t ha⁻¹ (3 years)⁻¹ from an initial planting density of 4000 stem ha⁻¹ in an upper landscape position. These differences partly reflected site hydrology, with water accumulating in downslope positions. Partitioning of tree components was variable between species, with root:shoot (R:S) ratio being significantly (P<0.0001) higher for E. occidentalis (0.5) compared with the other two species (0.3). Results suggest that biomass productivity can be optimized in this region by using high initial planting densities and recognizing the interaction of different species with site hydrology.