The paper which this Corrigendum refers to is available here: Monthly diameter and height growth of young Eucalyptus fastigata, E. regnans,and E. saligna

Variation in and relationships between wood, chemical, kraft fibre, and kraft handsheet properties were studied in 29 individual trees of Eucalyptus regnans F. Mueller, aged 20-21 years, grown in Kaingaroa Forest, New Zealand. Means and ranges of these characteristics for E. regnans were also compared with those for similar 29-tree samples from E. nitens (Deane et Maiden) Maiden and E. fastigata Deane et Maiden from the same forest, aged 15-16 years. The trees sampled of E. regnans were of lower wood density (in spite of their greater age) and had kraft fibres that were longer, broader, thinner-walled, and had higher levels of collapse than those of either of the other species. Eucalyptus regnans individual-tree pulps showed the widest range of apparent sheet density compared with the other two species but had a similar mean, which was well predicted by wood density or by the level of fibre collapse in handsheets. Eucalyptus regnans trees had a good pulp yield, similar to those of E. nitens. For a market kraft pulp, E. regnans grown for 15 years could be expected to give a kraft pulp very deficient in handsheet bulk.

Kraft fibre and pulp properties were assessed for 10-tree bulked chip samples from 8- and 11-year-old species/provenance trials of Eucalyptus globulus Labill., E. nitens (Deane et Maiden) Maiden, and E. maidenii Labill., grown on two sites south of Kaikohe in Northland, New Zealand. Mean basic density of bulked chip samples ranged from 447 kg/m3 for both ages of E. nitens to 576 kg/m3 for 11-year-old E. maidenii. Pulp yields for all wood types were similar, from 54.5 to 55.6%. The kraft fibres of E. maidenii were somewhat longer, with higher wall area (coarseness) than those of E. globulus, which were in turn of higher coarseness than those of E. nitens. Fibre collapse potential (as indicated by fibre width/thickness ratio) of both E. maidenii pulps and the E. globulus 11-year-old material was much less than that for E. nitens. For these six wood origins, pulps of premium quality were obtained from E. globulus aged 11 and from E. maidenii aged 8 years. The pulp from 11-year-old E. maidenii was too high in bulk, requiring excessive refining, and the pulps from E. nitens (aged 8 and 11 years) were deficient in bulk and unsuitable for many eucalypt market kraft end uses

Whole-tree basic wood density of individual trees of a variety of species has been determined in many different studies in New Zealand since 1977. These data were recently collated, and whole-tree values for each species have been aggregated across sites into 5-year age-classes, from <7 years up to 70 years. Means, ranges, and standard deviations of each species/age-class have been tabulated for a total of 968 trees and 13 species or species groups, with numbers of trees/species varying from 15 to 232. Sites sampled were mainly in the central and northern parts of the North Island (latitude 39¦30'-35¦25'S). Logarithmic regression equations fitted to the age-class mean densities for each species have provided predictions of whole-tree basic density with age and, in conjunction with predicted volume yields, were used in a related study to predict stem dry matter production per hectare for different species. The species included were: Acacia dealbata Link., A. mearnsii De Wild., cypresses (data from Chamaecyparis lawsoniana (Murray) Par., Ch. nootkatensis (D.Don) Spach x Cupressus macrocarpa, C. lusitanica Miller, and C. macrocarpa Gordon were amalgamated), Pseudotsuga menziesii (Mirbel.) Franco, Eucalyptus fastigata Deane et Maiden, E. globoidea Blakely, E. globulus Labill., E. maidenii Labill., E. muelleriana Howitt, E. nitens (Deane et Maiden) Maiden, E. pilularis Smith, E. regnans F. Mueller, and E. saligna Smith. Predicted mean whole-tree basic density (from logarithmic regression) for the eucalypts (30-year-old trees) varied from 452 kg/m3 for E. regnans to 623 kg/m3 for E. globoidea. No data at age 30 years were available for Acacia mearnsii and E. maidenii but their mean density was respectively 658 kg/m3 at age 14 and 572 kg/m3 at age 11 years. Whole-tree mean density was about 418 kg/m3 for the cypresses and 406 kg/m3 for Ps. menziesii, almost irrespective of tree age. A notable feature of these data was the great variability in density between trees in a stand, but variation in whole-tree density with age showed consistent patterns for different species, in spite of confounded effects of site and stocking.

Digital images of poplar canopies in the Bay of Plenty and East Coast were captured to develop a model to predict canopy closure in poplar stands as a function of basal area. A model to predict basal area as a function of site quality, age, and stocking was also estimated. The effect of canopy closure on relative understorey pasture production in poplar stands was investigated using existing data sources. It was concluded that a simple linear function was unlikely to adequately model this relationship, and a more complex function was consequently estimated. The equations to predict basal area, canopy closure, and understorey pasture production can be used in conjunction with data describing initial livestock-carrying capacity and the seasonal distribution of pasture growth, to predict the effect of site, age, and stocking on understorey livestock-carrying capacity in poplar stands.

Provenance and species trials of Acacia dealbata Link. (31 seedlots) and A. mearnsii de Wildeman (23 seedlots), together with one or a few seedlots each of A. decurrens (Wendl.) Willd., A. falciformis D.C., A. filicifolia Cheel. & Welch ex Welch. A. melanoxylon R.Br., and A. silvestris Tind. were planted at five sites in 1989 and at two sites in 1991. All trials were assessed in 1996 at ages 7 years and 5 years (for 1991-planted trials) for diameter at breast height (dbh), bole straightness (score 1-9), and malformation (score 1-5). A small subsample of trees from seven seedlots each of A. mearnsii (from two sites) and of A. dealbata (from three sites) were assessed for height, dbh, and wood density (5-mm pith-to-bark cores) at age 7 years. Acacia dealbata and A. mearnsii greatly outgrew the other species, and were of much better form than all except A. silvestris. Both A. dealbata and A. mearnsii showed large and significant differences between seedlots (mostly provenances) in diameter growth and bole straightness, and A. dealbata did in malformation. For A. dealbata trials aged 7 years, overall mean dbh varied from 206 mm at Kinleith to 145 mm at Tuki Tuki (Havelock North); for A. mearnsii (not assessed at Kinleith), site mean dbh ranged from 151 mm at Tuki Tuki to 135 mm at Pohangina (Palmerston North). Averaged across three sites, dbh of the best three seedlots of A. dealbata was 175 mm compared with over 162 mm for the best three seedlots of A. mearnsii. The seedlots of A. dealbata with better growth and form were reasonably free of malformation and their bole straightness was acceptable for sawlogs. All seedlots of A. mearnsii were much more sinuous in stem form than A. dealbata, such that very few trees would be straight enough for sawlogs. Height of A. dealbata averaged 12 m at Tuki Tuki and up to 15 m at Kinleith. Height of A. mearnsii averaged 12 m at Tuki Tuki and Emerald Hills. Basic wood density of A. dealbata averaged 369 kg/m3 at Kinleith, 371 kg/m3 at Emerald Hills, and 412 kg/m3 at Tuki Tuki. By contrast, wood density of A. mearnsii averaged 553 kg/m3 at Tuki Tuki and 556 kg/m3 at Emerald Hills. There was substantial variation between seedlots in both species, with a range of 348 to 437 kg/m3 for A. dealbata (averaged over three sites) and of 521 to 573 kg/m for A. mearnsii (over two sites). The better provenances of A. dealbata show promise for sawlog and pulpwood production, based on rapid growth rate, acceptable bole straightness and wood density, and (from other work) good sawing, seasoning, and appearance characteristics. The rapid growth rates and high wood density of A. mearnsii in New Zealand, as well as existing market acceptance of South African material for pulp, indicate a real potential for this species for pulpwood.

Species and provenance trials of eucalypts planted in Northland between 1988 and 1993 included several provenances each of Eucalyptus fastigata Deane et Maiden. E. regnans F. Mueller. E. saligna Smith, E. botryoides Smith, E. grandis Hill ex Maiden, E. nitens (Deane et Maiden) Maiden, E. globulus Labill, and E. maidenii Labill. Trials were all located between Kaikohe and Dargaville (latitudes 35¦31' to 35¦48'), with two trials at Carnation Road and two at Walker Road (aged 11 and 9 years) and one of E. nitens only at Karaka Road. Trial designs were mainly 64-tree square plots with two to five replicates. Trees were assessed for breast height diameter over-bark, bole straightness, malformation, and crown health. Results were expressed as provenance and species means at each site, and also as basal area per hectare over-bark, volume per hectare under-bark, and frequencies of crop trees, mortality, and runts (suppressed sub-dominants). Eucalyptus fastigata at its single test site showed best growth and health of all species (mean annual increment (MAI) at Carnation Road averaged 52 m3/ha) but suffered some basal and upper stem forking. Eucalyptus regnans averaged 50 m3/ha/year, with good crown health, but E. nitens of central Victorian provenances showed poor crown health and high mortality despite good earlier growth. Eucalyptus saligna (and E. grandis) grew more slowly than other species and showed a high frequency of runts. Eucalyptus maidenii, planted in only one subsidiary trial at Carnation Road (and at Knudsen Road), had better crown health, higher survival, and better growth than E. saligna, E. grandis, and E. globulus, though its volume growth appeared to be less than E. fastigata in the main trial. Eucalyptus nitens of central Victorian provenances was evidently poorly adapted and unlikely to continue its earlier good growth, and even the healthier NSW provenances appeared insecure. Eucalyptus fastigata was a clear winner for growth and health, followed by E. regnans. Eucalyptus globulus had generally poor health and slower growth than E. nitens. Eucalyptus maidenii, although a slower starter, had good crown health and good survival, and showed higher wood density (from other studies) than E. nitens and E. globulus, and by inference, E. fastigata and E. regnans. Eucalyptus saligna, originally the preferred species in Northland, produced much less volume than the other species. Eucalyptus botryoides failed completely due to early possum damage.

Rooted cuttings of Pinus radiata D. Don have been produced for more than 60 years (Field 1934; Jacobs 1939; Fielding 1954, 1964; Thulin & Faulds 1968). The effect of maturation or physiological ageing on rooting success of cuttings has been reported (e.g., Fielding 1964) but the strategic significance of ageing was not fully realised in the 1960s (Thulin & Faulds 1968). There are both advantages and disadvantages associated with physiological age (Menzies et al. 1988), and field trial results have now indicated that there is an optimum physiological age of 3-4 years when there are advantages of improved stem form with some ageing but not the disadvantage of early loss of stem diameter growth associated with older physiological ages (Menzies, Klomp, Holden, & Hong 1991; Menzies, Klomp, & Holden 1991; Forest Research Institute 1991). Reliable morphological markers of physiological ages are required to ensure that cuttings of the right age are selected for setting in nurseries for plantation establishment

A sample, comprising 3681 shipping containers, was selected randomly from containers landed at the ports of Auckland, Wellington, and Lyttelton in the period from September 1997 to May 1998. Each selected container was placed on a frame and all six sides of the container were examined for the presence of soil, plant, animal, or inorganic matter. Isolations for fungi were made from all soil samples found on containers (1150 in total) and nematodes (and other soil meso- and micro-fauna) were extracted from 347 soil samples. All plant material was examined microscopically for the presence of pathogens. The insects, spiders, and other animals were identified as far as possible and their pest status was determined. A container was classified as "quarantinable" if any of the contaminants found on it included either viable pests or viable fungi belonging to genera which include plant pathogens or plant parasitic nematodes. Of the 3681 containers examined, 2240 (61%) carried no contaminants, 580 (16%) carried non-quarantinable contaminants, and 861 (23%) carried quarantinable contaminants. Among the quarantinable contaminants were pathogenic species of Fusarium and a live egg mass of the gypsy moth (Lymantria dispar (Linnaeus)). The quarantinable contamination rate of containers originating in different parts of the world varied from region to region: for example, it was 13.7% for containers originating from Korea, Taiwan, and Japan; 20.9% for Northern Europe; 21.2% for North America; 28.3% for Australia; 33.2% for Southeast Asia; 47.5% for the Pacific Islands; and 50% for South Africa. There were no regional differences in the proportion of quarantinable contaminants to the total number of contaminants and no differences in the quarantinable contamination rate were found for different cargo types or for different container types. It is concluded that the nature and the frequency of occurrence of contaminants on the external surfaces of shipping containers represent a risk to forestry in New Zealand. Further work needs to be carried out to quantify the magnitude of this risk.

A mathematical procedure was established to calculate a threshold tree/log radius above which the curvature adjustment required in Nicholson's "primary" procedure of measuring longitudinal growth strain may be omitted. The radius derived is a function of longitudinal growth strain on the surface of tree stems or logs, initial distance between measuring points, and the allowable error. The indication is that for all practical circumstances, it may not be necessary to account for curvature, based on the Kubler distribution of growth stresses. Formulas were also constructed to derive longitudinal surface strain under different circumstances

The development of planning models, which quantify the genetic influence on branch diameter at the family level, would enable forest managers to make informed decisions regarding the management of improved breeds of Pinus radiata D. Don. In a preliminary study of the genetic influence on branch diameter at the family level, progeny trials of both "850" seed orchard and long-internode selection series were sampled from a compartment in Kaingaroa Forest in the central North Island of New Zealand. Secondlog measurements of branch diameter and internode length were taken from 210 trees within 30 families across the "850" seed orchard and long-internode selection series. After branch index was adjusted for diameter at breast height, the residuals were regressed successively against mean internode length and branch cluster frequency breeding-value at the family level. Mean internode length was significantly correlated to branch index residuals within each selection series, but it was not correlated to branch index residuals across selection series. In contrast, branch cluster frequency breeding value was moderately correlated to branch index residuals both within and across the two selection series. The failure of mean internode length to completely account for differences in branch index between selection series suggests that forest managers may to a certain extent be able to manipulate branch index independently of internode length. Although this study showed that branch cluster frequency breeding value was correlated to branch index residuals across selection series at the family level, these findings are preliminary. If further research shows the relationship between branch cluster frequency breeding value, and branch index holds across other selection series, inclusion of branch cluster frequency breeding value in planning models may enable the genetic influence on branch index to be quantified at a more refined level than previously possible.

A simple method of assessing transplant stress was applied to data from three studies with bare-root Pinus radiata D. Don seedlings. A negative Transplant Stress Index (TSI) indicates seedlings have undergone transplant shock (the more negative the value, the greater the intensity of transplant stress). Negative TSI values occurred only during the first year after transplanting. Harvest treatments that included removing the forest litter affected TSI values on two sites. On one site, application of urea fertiliser increased the TSI. After the first year, TSI values were always positive. The TSI value appears to be a measure of seedling performance that is not directly related to either mean survival or mean initial height growth of the population. Stress Index can detect differences among treatments more quickly than comparisons of mortality

The developmental timing and cytological detail of male cone development and microsporogenesis in Pinus radiata D.Don (radiata or Monterey pine) growing in the central North Island of New Zealand were studied. Potential male cone primordia were formed by mid-January, and microsporophylls were initiated in late February, the late New Zealand summer. Unlike northern temperate pine species, development of microsporophylls and differentiation of the microsporogenous tissue progressed continuously from late February to early July without a break for dormancy. Meiosis, as inferred by nuclear changes prior to tetrad formation, occurred in late May and was completed by the beginning of July. Pollen was shed in July. Electron microscopy showed major ultrastructural changes during microsporogenesis. Early in development, well-developed plasmodesmata connected all the sporogenous cells and tapetal cells which contained vacuoles, plastids, mitochondria, dictyosomes, an extensive rough endoplasmic reticulum (RER) network, and an abundance of ribosomes. As the pollen mother cells differentiated, the number of plastids, mitochondria, and ribosomes remained abundant but, in contrast, the plasmodesmata between these adjoining cells became blocked and putative autophagic vacuoles appeared. The tapetal cells became radially flattened, their nuclei and cytoplasm were intensely basophilic, and the RER system became highly dilated to form wide channels containing fibrillar material. As development progressed further, a thick callosic wall isolated the pollen mother cells from the tapetal cells. Invagination of the pollen mother cell plasmalemma became prominent along with a reduction in the numbers of plastids and mitochondria.

Loblolly pine (Pinus taeda L.) and sweetgum (Liquidambar styraciflua L.) were grown with irrigation, continuous fertiliser application, and insect pest control on a 1- year-old abandoned peanut (Arachis hypogaea L.) field. Wells and tension lysimeters were used to measure nitrate-nitrogen (NO3-N) in soil moisture and groundwater on three replicate transects for 4 years. Each replication had five treatments: maximum plantation management, minimum plantation management, old field, natural forest, and lake edge. Maximum plantation management included improved genetic stock, irrigation, fertiliser, complete elimination of competing vegetation, and insect pest control. Minimum plantation management included improved genetic stock and complete elimination of competing vegetation. The old field was the abandoned peanut field with no treatment. The natural forest was 50-year-old longleaf pine (Pinus palustris Mill.) forest. The lake edge was a narrow wetland transition from the longleaf pine forest to the lake. During the first 2 years of plantation management, groundwater nitrate-nitrogen concentrations exceeded drinking water standards throughout the abandoned field and were highest on plantation plots. During years 3 and 4, groundwater nitrate-nitrogen concentrations declined. The greatest reduction of nitrate-nitrogen concentration occurred in soil moisture, at the shallowest depths, in the plantation treatments. After four growing seasons, biomass accumulation ranged from 7.5 Mg/ha for the sweetgum minimum treatment to 57 Mg/ha for loblolly pine maximum treatment.

The effects of surface soil disturbances induced by traffic during timber harvest on surface hydrology and early pine growth were assessed after harvesting of three 19-ha, 22-year-old loblolly pine (Pinus taeda L.) plantations in an Atlantic coastal wetland in the south-eastern United States. This study follows previous research on surface soil disturbances caused by harvesting under dry-weather and wet-weather conditions in order to address two basic questions: (i) to what extent does the extensive surface soil disturbance on wet-weather harvested sites affect overall surface water dynamics and tree growth, and (ii) can these harvest-induced soil disturbances be mitigated through site preparation with respect to hydrologie recovery and site productivity. Overall surface hydrology and tree responses to the two harvest treatments and three site preparation levels (no preparation, bedding, or mole-ploughing + bedding) were evaluated by monitoring the water table dynamics and tree growth on a 20 x 20-m grid across the sites. The study showed that surface soil disturbances affect hydroperiod, by showing a large difference in water table elevation during the growing season between the wet-weather harvested and the dry-weather harvested sites. Bedding lowered overall surface water table initially to a large extent, but this effect decreased rapidly during the first 2 years after stand establishment. No significant differences in tree growth at age 2 were found among undisturbed, compressed, and shallow-rutted areas within non-bedded, bedded, and mole-ploughed + bedded sites. Surface deformation such as deep rutting or churning, appeared to promote tree growth on the flat-planted sites, yet showed a negative effect on early tree growth on the bedded sites. At a stand level, above-ground biomass production at this young age was little affected by surface soil disturbances.

Mechanised forest harvest operations are a significant source of soil compaction for which intensive tillage is prescribed to alleviate soil compaction and ensure successful regeneration of planted pine trees. Soil strength is a potential indicator of compaction status of a harvest tract due to its sensitivity and the ease of data collection with a cone penetrometer, but estimates may vary widely throughout a harvest tract. A loblolly pine (Pinus taeda L.) plantation that had been harvested in winter 1998 was studied to assess soil strength and its spatial qualities through the measurement of soil strength on two sampling scales, and to identify areas of the harvest tract where tillage operations would be beneficial. Cone index measurements indicated a high degree of variability in soil strength regardless of the scale of measurement, and high soil strength levels throughout the soil profile. Spatial dependence was high in the surface and immediate subsurface soil layers of each point grid system and was attributed to the impact of traffic or topographic position on soil strength. Spatial dependence was not detectable for the lowest subsoil layers of the large-scale sampling scheme. The short ranges of spatial correlation associated with cone index estimations and the presence of compacted subsoil layers throughout the study area suggested the need to perform tillage throughout the harvest tract to ensure alleviation of subsoil compaction for adequate regeneration.

The annual increment in above-ground biomass, and the corresponding nutrient content of eucalypt plantations growing in nine different sites, were evaluated in order to analyse the growth and the nutrient accumulation of Eucalyptus spp. in Brazil. The sites represented a wide range of edaphic and climatic conditions, resulting in a large variation in growth increment and tree nutrient content. The highest productivities (approximately 36 t/ha·year) were observed in sites with the lowest water deficits. On average, the stem represents 89% of the above-ground biomass but it can be as low as 78% in the least productive site. The nutrient content in the stem was highest in the most productive sites, showing a close relationship with biomass production. There were two distinct patterns of stem annual nutrient accumulation. At three of the sites, the amount of nutrients in the stem decreased in the order nitrogen > calcium > potassium > magnesium > and phosphorus. However, calcium exceeded nitrogen at the other six sites. Nutrient use efficiency (NUE) for stem and above-ground biomass production was significantly different among sites. On average, the values of NUE for both stem and above-ground biomass decreased in the order phosphorus > magnesium > potassium > nitrogen > calcium. Unlike dry matter, there were appreciable differences among sites in relative nutrient allocation. Although bark constitutes only 10% of the above-ground dry matter, it contains large amounts of nutrients (73% of the calcium in the stem, 65% of the magnesium, 46% of the phosphorus, 41% of the potassium, and 24% of the nitrogen). Debarking in the field can substantially reduce nutrient exportation, which could lead to greater sustainability or less fertiliser use in eucalypt plantation forests of Brazil.

Identifying the critical soil- and site-based determinants of pine productivity is a crucial part of developing management practices that facilitate maintenance and enhancement of long-term site productivity. The objectives of this analysis were to: (i) determine the relationships between soil and site properties controlling early loblolly pine (Pinus taeda L.) productivity, and (ii) determine the effects of site preparation on these relationships. Fifty-four loblolly pine bioassay plots were established across a gradient of soil disturbance, organic debris removal, and site preparation methods. These mini-stands were designed to simulate the growth response of commercially spaced trees to the disturbance/site preparation gradient at stand closure. Several soil and site properties were selected as indicators of the three dominant soil attributes controlling tree productivity - (i) promotion of root growth, (ii) air/water balance, and (iii) soil fertility and they were measured at each of the 54 bioassay plots. A multilinear regression analysis showed that soil oxidation depth (air/water balance), the Least Limiting Water Range (LLWR) (promotion of root growth), and net nitrogen mineralisation (soil fertility) were the most important soil indicator variables explaining pine productivity. A multiple interaction model with dummy variables included for the site preparation methods showed that oxidation depth interacted strongly with the LLWR and net nitrogen mineralisation, with the model explaining 87% of the variation in 2-year-old tree height. The model showed that oxidation depth was the most important soil variable affecting early tree growth, having large positive effects on tree height even for soils with very poor physical quality (low LLWR). Bedding increased 2-year-old tree height compared to that in non-bedded plots. The bedding response was attributed to a doubling in oxidation depth, and secondarily to improved net nitrogen mineralisation. There was an optimum oxidation depth above and below which tree growth declined, showing that these sites experienced both aeration and available water-limiting conditions. The optimum oxidation depth was 30 cm, which corresponded to an average water table depth in winter of 43 cm. High net nitrogen mineralisation offset the negative effects of high oxidation depths; trees growing on well-drained locations with high nitrogen availability and oxidation depths in excess of 30 cm outgrew trees growing on well-drained locations with similar oxidation depths and low nitrogen availability. These results suggest that with taller beds, and especially with internal drainage treatments such as the mole-plough, soil fertility may have to be increased with fertiliser application if the inherent levels of fertility are low and the goal is to maximise pine production.

Soil organic matter (SOM) is generally assumed to be important to forest productivity, but its direct influence has been difficult to clearly demonstrate. SOM has a myriad of interactions with other soil properties, and levels of SOM depend on plant factors such as productivity and litter chemistry, and on environmental factors such as temperature and water. SOM is thus both cause and effect with respect to productivity. Additionally, SOM is inversely related to productivity where conditions such as low temperatures or reduced aeration are adverse for both plant growth and for microbial activity, and SOM accumulates. Conventional experimental methods arc unlikely to provide a wholly-inclusive general demonstration of the effects of SOM on forest productivity because the relationship is complex and site-specific. In spite of that caveat, circumstantial evidence indicates that SOM positively affects long-term forest productivity, with its specific role and contribution depending on the limiting site factors. In coarse-textured soils, SOM is important for retaining water and for supplying and retaining nutrients. As soils become finer, those roles become less important but its role in promoting favourable soil physical properties increases. Forest management practices can alter the amount and type of SOM, but because inherent soil or site characteristics sometimes compensate for or mitigate the effects of SOM change, the direct impacts on productivity may be equivocal. Nonetheless, because of the strong ties of SOM to a wide range of soil properties and functions across soil textures, most prudent forest management regimes should maintain or enhance SOM levels.

Soil organic matter (SOM) is generally assumed to be important to forest productivity, but its direct influence has been difficult to clearly demonstrate. SOM has a myriad of interactions with other soil properties, and levels of SOM depend on plant factors such as productivity and litter chemistry, and on environmental factors such as temperature and water. SOM is thus both cause and effect with respect to productivity. Additionally, SOM is inversely related to productivity where conditions such as low temperatures or reduced aeration are adverse for both plant growth and for microbial activity, and SOM accumulates. Conventional experimental methods arc unlikely to provide a wholly-inclusive general demonstration of the effects of SOM on forest productivity because the relationship is complex and site-specific. In spite of that caveat, circumstantial evidence indicates that SOM positively affects long-term forest productivity, with its specific role and contribution depending on the limiting site factors. In coarse-textured soils, SOM is important for retaining water and for supplying and retaining nutrients. As soils become finer, those roles become less important but its role in promoting favourable soil physical properties increases. Forest management practices can alter the amount and type of SOM, but because inherent soil or site characteristics sometimes compensate for or mitigate the effects of SOM change, the direct impacts on productivity may be equivocal. Nonetheless, because of the strong ties of SOM to a wide range of soil properties and functions across soil textures, most prudent forest management regimes should maintain or enhance SOM levels.

A study was installed in the Lower Coastal Plain near Washington, North Carolina, to test the hypothesis that incorporating organic matter in the form of comminuted forest slash would increase soil carbon and nutrient pools and alter soil physical properties to favour pine growth. Two sites were selected, an organic and a mineral site, to compare the treatment effects on the different soil types. The mulching treatments included a surface broadcast mulch, a surface strip mulch, and a strip mulch and till. On the mineral site, the three treatments resulted in general decreases in soil bulk density, gravimetric soil water content, and soil strength. Soil carbon and nitrogen increased for all the treatments on the mineral site, with some significant differences between the treatments. The broadcast mulch and bed treatment resulted in an almost 100% increase in soil carbon and nitrogen. On the organic site, the treatments did not have a significant effect on soil physical properties or soil carbon and nitrogen. There was a consistent decrease in soil carbon and nitrogen on this site but these changes were not significantly different from those in the control treatment.

The concept of using multiple rotations of fast-growing fibre/energy plantations for restoring soil capacity was evaluated using the CO2FIX model. The simulation analysis considered portions of such stands being incorporated back into the soil at the end of each rotation and with different product scenarios. The analysis of nine simulated scenarios illustrating a range of mixes of energy, pulp, and solid wood products, as well as incorporation of biomass into the soil and productivity differences, using the model CO2FIX showed: (1) shifting the mix to more durable products significantly increased the amount of carbon sequestered, (2) increases in stand productivity increased carbon sequestration potential, and (3) productivity increases and incorporating biomass into the soil appear to have the biggest payback for carbon management. These simulation results show there may be potential for the use of short-rotation woody crops as a way to mitigate previous long-term soil depletion activities and to increase carbon sequestration. Research needs indicated by this simulation analysis include: (1) appropriate functions for decomposition and transformation of buried biomass for incorporation into carbon management models, (2) incorporation of feedback mechanisms into carbon management models reflecting the impact of soil and management changes on productivity, and (3) a means of crediting carbon as offsets to fossil fuel in a closed-loop biofuel cycle.

This paper documents the harvesting costs for a representative wildland-urban interface zone project around Flagstaff, Arizona - the 134-ha Fort Valley Research and Demonstration Project. The economic impacts of three treatment prescriptions on three types of Pinus ponderosa P. Lawson et Lawson (ponderosa pine) stands utilising three different harvesting techniques were analysed. In addition, the opportunities of two potential bioenergy markets were examined from the harvesters' revenue perspective. The costs of fully mechanised harvesting of the whole tree(WT) and hauling merchantable-size logs equalled US$28/m3, when averaged over the three different prescriptions in the three blackjack (BJ) units. There was little variation in WT cost from unit to unit. Under a direct cost hand-felling and mechanised-forwarding scenario (HD) scenario, the predicted costs, when averaged over the three blackjack-yellow pine (BJ/YP) units, equalled US$25/m3. Similarly, the cost to treat the three yellow pine (YP) units with a small cut-to-length forwarder system (CTL) averaged US$26/m3. The variation from unit to unit, however, for the HD and CTL operations was significant. The costs were a function of volume per unit area and average volume per tree and varied from a low of US$19/m3 to a high of US$43/m3. A comparative analysis of the three harvesting operations found the WT operation to be the most cost-effective in BJ and BJ/YP units. A slow forwarding system limited HD and CTL effectiveness. In the YP units (characterised by excessive numbers of closely spaced, very small, blackjack trees surrounding widely spaced, mature, yellow pine trees), forwarding times were no longer of consideration. Cutter rates and associated expenses became the dependent economic variable. The pre-commercial work in the BJ and BJ/YP units was modelled as a minimal-cost operation using a contract sawyer crew. These costs were found to average, respectively, US$21/ha (US$0.28/tree) and US$193/ha (US$0.15/tree). Within the YP units, the CTL machine completed the pre-commercial work as it made its way through the units cutting the available merchantable trees. This slower operation resulted in very high pre-commercial costs, averaging US$393/ha (US$0.36/tree). The economic analysis of an existing solid firewood market from the harvesters' perspective indicates that a high-value pole market subsidises the lower value firewood opportunity. The ethanol projections were not favourable and the fibre costs were prohibitive.

Bioenergy provides more power than either hydroelectric or nuclear power, accounting for 87 TWh per annum (1996) and nearly 20% of the total power generated. The total consumption of energy wood amounts to 20 million m3 solid including biomass direct from the forest, by-products from the forest products industry, and a small quantity of recycled timber. This should be seen in the context of a total annual cut of some 60 million m3 roundwood for industrial consumption. The energy wood that is available on the open market consists largely of wood straight from the stand, wood reduced to chips, and other comminuted biomass. We utilise annually roughly 4 million m3 biomass, mainly logging residue from final felling. The energy-wood sector is currently in a state of high activity. The demand is heavy in the vicinity of large towns in some parts of the country. There is also an increasing awareness of the need, for ecological reasons, for well-thought-out recommendations as to where and how energy wood should be exploited.

Recent developments in the provision of subsidies for large-scale electricity generation in the United Kingdom have created annual markets for some 400 000 oven-dry tonnes of wood fuel from the year 2000. However, wood fuel supply costs are only on the very edge of economic viability. There will have to be major technological advances in the supply chain to contain costs, and to ensure an adequate profit element for harvesting contractors to encourage capital investment in wood fuel harvesting equipment. A number of harvesting systems are likely to be adopted in the United Kingdom. Trials into residue compaction systems linked to large-scale comminution at the generation plants are currently ongoing and, subject to results, are likely to form one of the supply systems to be adopted. Compaction trials of the Swedish Bala Press baling system were carried out in the United Kingdom in 1996 and 1997. Results of the trials indicated greater productivity was needed to reduce costs. Trials in 1999 are concentrating on the Swedish Fibrepac compaction equipment that is being introduced into a number of harvesting systems. Investigations are also ongoing into road and rail transport of the compacted residues.

Bioenergy provides more power than either hydroelectric or nuclear power, accounting for 87 TWh per annum (1996) and nearly 20% of the total power generated. The total consumption of energy wood amounts to 20 million m3 solid including biomass direct from the forest, by-products from the forest products industry, and a small quantity of recycled timber. This should be seen in the context of a total annual cut of some 60 million m3 roundwood for industrial consumption. The energy wood that is available on the open market consists largely of wood straight from the stand, wood reduced to chips, and other comminuted biomass. We utilise annually roughly 4 million m3 biomass, mainly logging residue from final felling. The energy-wood sector is currently in a state of high activity. The demand is heavy in the vicinity of large towns in some parts of the country. There is also an increasing awareness of the need, for ecological reasons, for well-thought-out recommendations as to where and how energy wood should be exploited.

Integrating the planning and implementation of wood-based fuel production with the procurement of industrial roundwood in conventional forestry is considered to be a feasible undertaking. When doing so, the logging sites potentially serving as sources of biomass residues to be salvaged for fuel need to be chosen on the basis of harvesting costs. It is essential to take carefully into account site-based cost factors such as the total volume of wood to be obtained from the site, site conditions, available equipment and operating technologies, off-road haulage and truck transportation distances, storage, and quality control. In addition, ecological sustainability, possibilities to concentrate operations, seasonal variation in consumption, and the wishes of land-owners also affect the choice of harvesting sites. An important factor is the scale of operation. Harvesting machinery is expensive and thus the annual output considerably affects the costs. In addition, the greater the share of the potential fuel supply recovered, the higher the cost of procurement. This is due to longer transport distances and the need to operate on less favourable sites. As regards deliveries of different wood fuels or fuel mixtures, the quality of the fuel and the demands of energy-generation plants should be also considered. The present situation in Finland and Sweden is such that the wood fuel delivered directly from the forest to users is recovered almost solely from final cuttings in the form of logging residues. Wood fuel obtained from thinning operations is of minor importance.

This paper presents a framework for community-based forest management planning for bioenergy in remote Aboriginal communities in Canada. Modelled after work done by the National Aboriginal Forestry Association and provincial government agencies, the proposed approach to forest management planning provides the necessary information and format to develop a long-term and integrated resource management plan. It is designed to be adapted as part of a small-scale forestry operation to supply wood-chips for burning in biomass heating facilities. The framework allows individual communities to modify the format to suit their needs, and recognises and plans accordingly for the unique circumstances and characteristics of remote Aboriginal communities. The framework includes information for completing a plan including: period, land description, history, maps, biomass and non-timber inventories, sustainable harvest levels, activity schedules, monitoring, and review. Aboriginal involvement in broad district-level forest management plans is discussed in relation to and comparison with participation requirements for management planning for community-based bioenergy projects.

A new national energy technology programme, Wood Energy, has been launched in Finland by the National Technology Agency (Tekes). The programme's total budget for 1999-2003 is F1M250 million (US$45 million), Tekes' share of which amounts to FIM50 million. The programme is co-ordinated by VTT Energy. In 1998, the energy use of forest chips amounted to 0.5 million m3 solid. The target of the Wood Energy Technology Programme is to increase the annual use of forest chips to 2.5 million m3 solid in 2003, i.e., five-fold in 5 years. It is obvious that the target can be achieved mainly by increasing the use of logging residues from final cuttings, since salvaging residues from cut-over areas is more cost competitive than harvesting smallwood from young sapling stands and early commercial thinnings. Nevertheless, chip production from thinning of young stands will be developed as well. Increasing the use of forest chips requires that the cost of production is reduced still further, and that is naturally one of the main objectives of the programme. The programme is also helping to develop quality control and storage of wood chips. The quality of chips can be seen as an important cost factor, since the amount of heat obtained from the wood chips, the emissions produced, and the reliability of delivery and use all depend upon it. Improvement of chip quality is not confined solely to forest chips, but it is just as important for wood residues from primary timber processing at mills. For this reason the scope of the programme also includes bark, sawdust, and other solid wood residues from the forest products industry that are suitable for fuel.

In conventional forest management the fast-growing hardwoods such as birch (Betula pendula Roth and Betula pubescens Ehrh.) are cleaned when they start to compete with the conifers. In general, the naturally regenerated birch trees of minimal energy value are removed when they are 2-4 m high and start to suppress the undcrstorey of Norway spruce (Picea abies (L.) Karst.). Today with increasing interest in utilising biomass for fuel, mixed forest with a shade-tolerant main species and a fast-growing species combined could be an important supply of biofuel and also an important ecological site for maintaining biodiversity. An experiment was established 1983-85 on eight localities in central and southern parts of Sweden (lat. 58Ý-61Ý N). The stands were 20-30 years old when the experiment was started and consisted of dense, even-aged, self-propagated birch sheltering young Norway spruce either planted or self-propagated. All stands were growing on moist or mesic sites with high site indices. Thinning regimes included (1) thinning of the birch overstorey to create a shelter of 500 stems/ha (shelter) and (2) total removal of the birch overstorey (no-shelter). The treatments were replicated at each locality. The shelter was to be cut when the stand was 35-40 years old. When the experiments started the mean diameter of trees on all plots was 60 mm for birch and 45-49 mm for Norway spruce. The amount of birch biomass removed at first treatment was 40.6 Ý 3 (range 13.7-64.5) tonnes dry weight (dw)/ha for shelter plots and 70.0 Ý6 (range 34.9-142.7) tonnes dw/ha for no-shelter plots. In 1997 when all birch trees on shelter plots were cut, the amount of birch biomass removed was 45.3 Ý 5 (range 13.6109.3) tonnes dw/ha. Total amount of birch biomass during the period was 85.9 Ý7 (range 40.9-145.3) tonnes dw/ha for shelter plots and 72.7 Ý7 (range 34.9-142.7) tonnes dw/ ha for no-shelter plots. The remaining Norway spruce stands have produced 32.9(10.948.6) tonnes dw/ha growing under a birch shelter compared with 37.9 (5.0-63.4) tonnes dw/ha for pure spruce stands.

Four combinations of biomass value, stand condition, site, and management objective are discussed. An emphasis is placed on short- and medium-rotation coppice systems using natural and artificial regeneration. Artificial systems which parallel agricultural production require both very high yields and good biomass prices to offset high input costs. At present, low fossil fuel prices in Canada do not make utilisation of biomass for energy economically attractive. Government policy may dictate more biomass use for energy for political, environmental, and especially carbon balance reasons.