Eucalyptus Plantations

PREFACE.

CONTENTS.

For the last thirty years, the eucalypts plantations have experienced an important development in the subtropical and tropical zones. Successful genetic improvement amplified by vegetative propagation and more recently by promising biotechnology, has added to the natural qualities of the tree: fast growing, excellent fibre, and relatively high wood density. This has favoured Eucalyptus as one of the best tree species for ligniculture.

The high productivity and short rotation, along with the uniformity of clonal plantations and improvement of wood quality, attracted private investments, especially from the pulp industry that continues to invest in R&D to reduce the agronomic, pathological and ecological risks of this crop. Eucalyptus has also started to attract financial groups who have joined multinational pulp and paper companies in the investment of its plantation development.

After long time criticism by ecologists, this ligniculture is now better appreciated because it is usually developed on non-forested lands, contributing in fact to reduce the economical pressure on natural forests. This ecological interest is now enhanced by the recent progress in high quality timber production. It is a great new challenge to reinforce the economic and ecologic interests that could increasingly contribute to protect the natural forests. Last, but not least, Eucalyptus could become one of the best carbonsinks species, and so, one of the best ecological and economical tools for internalising the global externalities induced by the burning of fossil fuel. This new green gold of the pulp industry can now be considered a “strategic forest tree” as well.

Eucalypts are an established part of the landscape in parts of Asia, particularly China, Viet Nam and Thailand. As small, non-formal plantings they meet local needs for fuelwood, poles, lumber, essential leaf oils and tannins, and as large plantations they meet industrial needs for pulp, paper and reconstituted wood products such as MDF and particleboard.

Acacias have similarly being planted in large plantations in Southeast Asia to meet demands for commercial pulpwood. Over 900,000 ha of Acacia mangium have been planted in Indonesia and Malaysia, and about 100,000 ha of A. crassicarpa plantations have been established on sites with a high watertable and peaty soils on Sumatra, Indonesia.

Eucalypt and tropical acacia pulps are both high quality and short-fibred, with flexible end uses. Before trial shipments were presented to the European market in 1995, there were few opportunities to commercially assess acacia pulp. Currently about 1.9 million tonnes of tropical acacia pulp are produced and used internationally. When commercial plantations in Indonesia become operational in 2010, this supply of acacia pulp will exceed 4 million tonnes annually. Does this present a challenge to eucalypt pulp that shares many of its attractive features?

The capacity to competitively produce acacia pulp has been underpinned by considerable research, particularly into the domestication of these species. This has included characterisation of natural populations, identification of superior natural provenances, breeding, establishment of seed orchards and cloning of fast-growing hybrids. Nutrition research has demonstrated the value of phosphorus fertilisation on most sites and the benefits of inoculation with selected rhizobia and mycorrhizas. Potentially-damaging pathogens and insects have been identified. Development of management practices to maintain site productivity and plantation yield in successive rotations is critical, particularly for peat soils. There remain significant challenges to the ongoing commercial utilisation of tropical acacias but the high quality of their pulps and the extensive established plantation resource will ensure that their domestication will continue.

No abstract received.

This paper reviews the study of genetic resources and advances in the classification of the eucalypts with emphasis on the new taxonomic system put forward by K.D. Hill and L.A.S. Johnson. The eucalypts comprise three genera, Angophora Cav., Corymbia K.D. Hill & L.A.S. Johnson and Eucalyptus L’Herit., with over 945 taxa totally recognized at present. The effects of the taxonomic changes on domestication and practical forestry with eucalypts are discussed, in particular, with those taxa that have been important plantation species in China. Research direction in eucalypt domestication and tree breeding is also discussed.

In this documentation, ecological/environmental concerns/issues emerging from modern short-rotation plantation management are discussed. Most of these concerns/issues are associated with the intrinsic characteristics of fast-growing and short-rotation plantations. We propose that existing operation procedures are revised or new operation procedures are devised to meet the increasing demands of ecological/environmental conservation and sustainable development. Sino-Forest’s practices in South China were used for demonstration. While improving the status of the local/surrounding landscapes, ecosystems, biodiversity, vegetations, and conservation at the present situations in a short time, short-rotation plantations may still worsen sustainable management and slow down the process of ecological/environmental restorations in the regions in a long run. A management system with prescribed techniques or operations could minimize or reverse most of the potential impacts that plantations may have on ecological/environmental conservation.

Internationally, as the importance of forest plantations increases, investigations to boost forest productivities frequently take place. However, despite its importance, registration of forestry lands is often an overlooked subject in research or in actual administrative processes. This paper first describes experiences of land registration by Oji Paper Co., Ltd.’s overseas forest subsidiaries. Next, it describes the situation of forestry land registration in Southern China, where Guangxi Oji Plantation Forest Co., Ltd., a subsidiary forest plantation company of Oji Paper, operates. In Southern China, forestry land registration is legally defined, but actual registration appears still hampered by several factors. The lack of a registering system is the main physical barrier, while the general lack of understanding for the importance of forestry land registration appears an underlying cause. This paper emphasizes that efficient forestry land registration is one of the important factors in facilitating the development of industrial forest plantations.

Eucalyptus breeding efforts started relatively late, compared with conifers species and poplar. By 1980, only a few breeding programmes were in place, little was known about the genetics of the species, their reproductive biology and the best deployment schemes, including cloning and seed orchards. It is remarkable and inspiring that by now, some of the most advanced and focused breeding programmes in the world are from Eucalyptus. Today, several programs are now well into their 3^rd generation of breeding, leading the way in the use of clonal forestry and becoming one of the preferred species in the applications of genomics to forestry.

The paper will briefly review the progress in strategy, technology and outcome over time in eucalypt breeding, in par with the changes in forestry as a whole, and discuss what may be the lessons to take from this co-evolution. The general principles and restrictions underlying Eucalyptus breeding programs are presented and put in perspective. Finally, some of the opportunities for developing new and better programs are briefly discussed.

More than 900,000 hectares of eucalypt plantations have been established to date in China but these are concentrated in warmer coastal regions of southern provinces. Relatively small areas have been planted to date in cooler areas of south central China - areas where some eucalypt species can grow well. These cooler areas include much of China’s ‘red soils region’ which contains large tracts of eroded wasteland; land that is often suitable for forest plantation establishment.

The mean growth of eucalypt species across sites in cooler areas of south central China is summarised. Performance of those species that have been included in trials at three or more sites for each of two distinct environments – the Yunnan Plateau and then lower elevation areas – is reported. The lower elevation sites are spread across Hunan, inland Fujian and northern Guangxi provinces. Eucalypts that have demonstrated the best potential on the Yunnan Plateau include E. globulus, E. maidenii, and E. smithii. In other south central provinces where the target sites are below 1,000 m elevation, E. dunnii, E. camaldulensis and, for milder sites, selected sources of E. grandis have shown good potential. E. nitens and a range of other cold tolerant eucalypt species warrant further testing and evaluation across the region, but only if this is well coordinated with good communication and collaboration among researchers and institutes.

Significant genetic variation in cold tolerance has been demonstrated within some of the key eucalypts for south central China, providing opportunities to improve their adaptation for cooler sites. However, it emphasized that attention must also be focused on soil, nutritional and silvicultural management for eucalypt plantations to be successful in this region.

The difference in and correlation among major characters of eucalypt (species) hybrid clones were studied by investigating and analyzing the performance of 27 different eucalypt clones at 3-year old. Clones significantly differed in the mean annual volume growth and had significant interaction with the conditions of the test sites. A clone’s tree form index had significant negative correlation with the yield; the pattern of the correlation between the major characters was different. Tree height and DBH had significant genetic and phenotypic correlation. As expected, DBH was the main factor in determining the plantation yield. Combined evaluation was given to the clones studied by using tree form index and unrestricted index selection. Eighteen superior clones including EC1, CH3 and CH1 were selected for developing eucalypt plantations.

Impact of fertility variation in a progeny trial of Eucalyptus tereticornis in south India was studied at four years of age with the intention to convert it to a seedling seed orchard. A hypothetical phenotypic selection of 200 trees for tree height resulted in only 18% fertile trees. There was tremendous variation in fertility (sibling coefficient, A=17.4). This would cause excessive representation of the 12 most fertile trees resulting in high genetic drift, inbreeding and low status number (N_s=8.5). Collection of equal quantities of seed per tree would reduce sibling coefficient and almost double the status number in seed crop. Much of the diversity loss occurs in the first generation as indicated by 65% decline in relative status number in the first generation compared to six advanced generations. Retaining 35 additional pollen parents would increase status number and variance effective population size by 100% in the first generation, but reduce gain by 2% compared to the trees selected for genetic merit. Both strategies would reduce inbreeding coefficient in the second generation. Combination of the two - retaining trees for pollination only and limiting the number of seeds harvested from individual trees would reduce impact of fertility variation in seedling seed orchards and be useful as management strategies in domesticating tropical eucalypts.

Tissue culture is a very important technology for the research and development of Eucalyptus plantation. Up to date, about 60 Eucalyptus species have been studied with tissue cultural methods including use of tissues, cells or organs from seed, shoot, floral bud, lignotuber, callus, root, anther, suspension, protoplast and somatic embryo. Plantlets have been obtained for most of the species studied.

The photosynthesis of six 3-month-old superior eucalypt clones that are widely extended for plantation purpose was tested. The light response saturation point of E. urophylla was between 1800-2000 μmol/m²/s; the net photosynthetic rate (Pn) and irradiance had a quadratic correlation. Significant difference in photosynthesis of seedlings was found among eucalypt clones. Transpiration rate (E) and Pn of the eucalypt clones were higher than other local broad-leave tree species. Not only did some clones of E. urophylla × E. grandis and E. urophylla × E. tereticornis grow faster than clones of E. urophylla × E. camalduensis and E. urophylla, but also had higher water use efficiency (WUE) and photosynthesis ability. Daily variation of Pn, E and leaf conductance (Cond) of different clones are similar. Leaf intercellular CO₂ concentration (Ci) and Pn of different clones changed in opposite direction but showed the same pattern. Pn, Cond and WUE had positive correlation with the height, DBH and individual volume. Photosynthesis testing was suggested to assist early selection of superior eucalypt clones.

Sophisticated or futuristic tree improvement, which requires large resources, stable funding, competent and permanent technical staff and well-developed infrastructure, is well represented in the qualified literature, in scientific research, in available expertise and in formal training programmes. In contrast, methods particularly suitable for breeding in resource poor situations may be neglected or used inefficiently, as little thought is given to adequately develop, implement and optimise these methods. The use of low-input, simple, robust and cheap methods may actually be justified also in comparatively resource rich environments, but suppressed because they do not seem sophisticated and advanced enough.

A number of low-input techniques for seed production and long-term breeding are discussed. In particular: phenotypic selection, absence of testing, unidentified plants, no grafting, and forwarding the breeding population by wind pollination instead of controlled crosses. Sustainable and optimally used low-input strategies require advanced quantitative genetic considerations, in particular concerning the management of relatedness. Vegetative propagation may be a valuable tool both in poor and rich situations.

The sites available to the South African forestry industry for commercial afforestation of eucalypts for pulp and paper production are diverse, and often termed as low in productivity. To manage the various limiting factors in the temperate areas, such as severe frost, low temperatures, occasional snow and drought and high altitude pests, a combination of matching site and species, together with the use of genetically improved material, is recommended to maximise gains from the sites.

To this end, site-species trials were established over several sites to investigate alternative species for growth on high altitude sites. Species such as E. nitens and E. macarthurii grow very well on the sites which are more extreme for cold and frost, E. dunnii and E. smithii on the more intermediate sites, and the new species, E. badjensis and E. benthamii have shown great potential as possible alternatives to E. nitens and E. macarthurii respectively. Breeding programmes have been initiated to test provenance and progeny in these species.

These species will be discussed with reference to site suitability, and results from provenance/progeny trials in the various species will be presented, including yield, pest and disease and pulping information.

Thirty-two open-pollinated families of Eucalyptus urophylla from the superior trees selected from a seedling seed orchard located in Suixi Forest Experiment Farm, Guangdong Province were included in a progeny test at Leizhou State Forestry Bureau to examine the genetic performance of the orchard. Compared to seed stand and imported commercial seed-lots, genetic gains in individual volume for the unrogued seedling seed orchard were 5.2% and 16.1%, respectively. For the advanced clonal seed orchard established with superior trees selected, the estimated gains would be 10.4% and 31.3%, respectively. Seeds from these orchards were recommended for developing plantations in the areas of West Guangdong.

A computer simulator called breeding cycler has been developed to evaluate a complete cycle in balanced long-term breeding from parents to the next generation parents through testing selection candidates obtained by mating in the breeding population. The efficiency of a breeding program was defined as progress per year at a given annual cost (GMG/Y). Progress was measured as increase in a weighted average of breeding value and gene diveisity, thus the loss of gene diversity is considered. Breeding cycler considers three testing strategies for evaluating candidates for the breeding population: Phenotype, Clone and Progeny. Breeding cycler requires a set of inputs, like annual budget, cost components, time components and genetic parameters, which were specified in a main scenario and each parameter was studied over a range with the aim to make the study relevant for much Eucalyptus breeding. Optimal test time and entry size was decided for each testing strategy and the testing strategies were compared. For the main scenario values, the maximum GMG/Y for the Phenotype, Clone and Progeny strategies was 0.42%, 0.636% and 0.331 %, respectively. The Clone strategy was superior and the Phenotype strategy was the second best under all input values studied. However, in the case of low heritability, cheap testing and long rotation the differences between Phenotype and Progeny strategies were small. Heritability, additive variance at mature age, rotation age, plant-dependent cost and time needed to produce the test plants had the strongest effect on GMG/Y. As increase of genotype-depended costs had a small effect on GMG/Y, investments in shortening the time until the females reach fertile age or in improving the success of cloning may pay off. In conclusion, to achieve the greatest benefit in long-term breeding, the breeding strategy shall primarily be based on clonal testing if this is practically possible, except for high heritability, when Phenotype testing can be the first choice. If cloning is not available, Phenotype strategy could be preferable at short rotations and high testing costs. The situation where Progeny testing is most favourable is when the heritability is very low, rotation is greater than 20 years, test plants are cheap to obtain, annual budget is large and flowering is early.

The results of Eucalyptus tereticornis provenance/families trial involving 100 families within 14 provenances showed that there were highly significant differences in growth and other characteristics among families and provenances. Growth characteristics were closely correlated with stem form (SF) and under branch height (CBH) except branch size (BR). Individual and family heritabilities were relatively high. At an age of 7 years old, the mean values of height (H), DBH and individual volume (V) of the best provenance (No.13659) were 1.27, 1.32 and 2.14 times, respectively, of those of the worst provenance (No.13308). Mean individual volume of the best family (No.17) (0.06134 m³) was 3.61 and 1.74 times of those of the worst family (No.33) and the whole population (all families), respectively. By using multi-trait index as the criteria, 22 superior families were selected, and the estimated gains were 7.31%, 6.39%, 18.01%, 13.77%, 8.22% and 5.36% for H, DBH, V, CBH, SF and BR, respectively.

The genetic effects of general (GCA) and specific (SCA) combining ability, paternal (MAL) and maternal (FEM) parents, and specific reciprocal cross (SRE) were estimated for height, diameter at breast height (DBH), volume, crown-width, under branch height, crookedness and ratio in diameter of branch to stem in Eucalyptus globulus. Three wood growth characters, i.e. tree height, DBH, and volume, were focused, and their genetic effects were discussed in detail. GCA, SCA and SRE were most significant, but FEM and MAL were minor. Three parents with high GCA were good materials for establishing seed orchard. Eight combinations significantly contributed to the improvement of the wood growth characters. A breeding strategy and the corresponding methods were discussed.

The genetic effects of general (GCA) and specific (SCA) combining ability, parental (MAL) and maternal (FEM) parents, and specific reciprocal cross (SRE) were analyzed for height, dbh, volume, crown-width, under-branch height (UBH), crookedness and ratio in diameter of branch to stem (RBS) in Eucalyptus maidenii. Three wood growth characters, i.e. height, dbh, volume were focused, and their genetic effects were discussed in detail. SRE accounted for most of the total variance in wood growth characters, followed by MAL. GCA accounted for 39.4% of the total variance in UBH, but contributed almost nothing in other traits although two parents tested had high value of GCA. While SCA affected crookedness and UBH, FEM explained much of the total variance in crown-width, UBH and RBS. Selfing incurred serious depression. Eight crosses performed better than the population mean in wood growth characters. The best strategy to improve E. maidenii is to breed superior crosses, select superior trees from the superior crosses and to asexually mass-propagate the superior individuals for production (plantations). With the materials available in the region, seed orchard is an inefficient method in terms of genetic gain.

Micronutrient disorders, especially B, Cu, Fe, Mn and Zn, have been recorded for eucalypts in nearly all the geographical regions where commercial plantations have been established. Whilst micronutrient disorders are often induced by the application of fertilisers containing only macronutrients, instances of primary B deficiency in China and Cu deficiency in Australia have been recently documented. Increasing records of micronutrient disorders in plantation eucalypts suggests that the capacity of micronutrients to limit productivity has not been adequately recognised in the past. Dramatic growth responses can occur with corrective fertilisation particularly where a micronutrient deficiency has been debilitating for growth. However, where deficiencies of elements have resulted in severe crown dieback and loss of form, it is very difficult to restart growth with good form. This paper describes the visual impact of micronutrient disorders on eucalypts in plantations, their effect on wood production and wood quality, and explores strategies for micronutrient management.

Since the 1980’s, eucalypts have been extensively planted mainly in the tropics and subtropics to help meet the worlds need for timber and fiber. The Dongmen project (1981-89) was established under the Australia-China Program of Technical Cooperation and represented the first major attempt in China to systematically test a wide range of fast growing species under a range of silvicultural regimes on degraded soils. During the life of the project more than 60 silvicultural experiments covering in excess of 1000 ha were established and maintained. The results of experiments to assess the eucalypt species/provenance by fertiliser interactions are reported. The experiments were established on Dongmen Forest Farm on degraded Acrisols representative of large areas of land potentially available for reforestation.

The most productive species/provenances were: Eucalyptus urophylla, E. cloeziana (Gympie provenance) and the hybrid between E. grandis and E. urophylla. Applications of mixed fertiliser containing: nitrogen (N) at 100 kg/ha, phosphorus (P) at 50 kg/ha, potassium (K) at 50 kg/ha and a trace element mix (TE) resulted in an improvement in total volume mean annual increment (for experiments aged between 5.6 and 10.9 years) of 6.1 m³/ha/yr for the best three performing taxa. All species/provenances responded in an essenially similar fashion to fertilising. The variability in species performance and fertiliser responses between trials highlights the need for replication in space and time and care to be exercised in the extrapolation of results to different climatic/edaphic regions. It was estimated that the internal rate of return by investing in fertilising was of the order of 30-35%.

Extensive use was made of foliar nutrient analysis to help interpret fertiliser responses and estimated ‘critical ranges’ for the major nutrients and ‘adequacy levels’ for the elements not limiting tree growth at Dongmen were summarized.

No abstract received.

Fertiliser management for optimal productivity in monoculture forest plantations involves key processes including site-specific prediction and on-going calibration (in terms of tree growth and nutrient requirements), and decision-making (in terms of fertiliser management plans). These processes are ultimately dependent on the integrity and representativeness of the databases on local conditions, tree growth potential and soil fertility indicators. Given the fact that data collection is a costly exercise, it is important to identify the scope of data entities that are economically achievable and scientifically sound, and logical processes that are required for mining the databases for decision making. Four key components of the system framework proposed are: (1) growth modelling of total and component biomass at the tree and stand level; (2) databases of internal nutrient requirements in trees and nutrient loading in biomass components; (3) databases of available nutrient pools in the soil; and (4) databases about fertilisers’ effectiveness in terms of replenishing available nutrient pools in soil. The framework presented here is by no means complete, but serves as a starting point for detailed data and process modelling and field calibration.

The impacts of alternative strategies for managing harvest residues in second rotation Eucalyptus globulus plantations are being examined at sites of contrasting soil fertility status in south-western Australia. This research is a component of the CIFOR network project, “Site management and productivity in tropical plantation forests”, in which common core treatments are being evaluated at 16 sites in 8 different countries. Our project is part of a collaborative study with Kerala Forest Research Institute, India, supported by funding from Australian Centre for International Agricultural Research (ACIAR). In Australia, treatments being examined in randomized block experiments are complete harvest residue removal (BL0), residue retention (BL2), increased residue (BL3) and residue burning (B). We studied (i) impact of treatments on soil carbon and nutrient stores, (ii) dynamics of soil N mineralization and (iii) nutrient uptake and tree growth. Results up to 5.5 years after stand re-establishment following harvest of the first plantation rotation are reported. Significant impacts of harvest residue management on stores and fluxes of C, N, P, Ca and Mg have been found. However, application of harvest residues at high rates (up to 160 t/ha) has had a surprisingly small effect on organic C levels in the surface soil. The dynamics of soil N is particularly affected by residue treatments; higher rates of retention of residues leading to higher rates of mineralization and potentially available N. Nevertheless, the rate of supply of N through mineralization from soil organic matter and residues may be less than the requirement for N of newly established seedlings of the next tree crop on many sites. Hence conservative harvest residue management will only partially satisfy tree nutrient requirements at these sites. In such circumstances, N supply needs to be augmented with fertilizer to achieve optimum plantation productivity.

This study investigated the interaction of Klebsiella oxytoca NG13/pMC73A with Eucalyptus. K. oxytoca colonized rhizosphere, the root surface and even the inner cortex of eucalypt seedlings. The inoculation of the bacteria stimulated the excretion of Eucalypt root system and affected the components of amino acids, carbohydrates, phytohormones of root exudates. Compared to the control, inoculation of the bacteria significantly increased the height growth, dry matters, N contents etc of Eucalyptus seedlings.

Process-based models are increasingly being applied as a planning tool by forest managers. The 3-PG forest model offers significant benefits for application to Eucalyptus plantation management in southern China. In addition to providing a rational basis for decisions on stand establishment, tending and harvesting, a well-constructed model may act as a framework for storage and retrieval of tree performance data and an indicator of priority areas for research.

Measurements of tree and stand growth, biomass relationships and water use from plantations on the Leizhou Peninsula of western Guangdong Province have been used to estimate model parameter values for major commercial eucalypt genotypes. The rapid early growth, high stand density and short rotations adopted by forest managers for woodchip production necessitate special forms of some parameters not included in other implementations of 3-PG.

Climate data inputs for modelling may be satisfactorily estimated from routine daily meteorological observations including temperature, rainfall and sunshine duration. Physiological parameters which are not amenable to direct measurement may be estimated by fitting the modelled growth predictions to one or more sets of growth observations, ideally for multiple species on sites with a range of climate and soil conditions or stand densities. The accuracy and reliability of modelled predictions will improve over time as more data sets become available to incrementally improve the precision of estimated parameters.

A field trial was initiated in 1995 to a Eucalyptus hybrid clone (GC540) to evaluate either the effects of various residue management options on weed and tree growth, or selective weed control on tree performance. This trial was situated in the coastal sub-tropical Zululand region of KwaZulu-Natal, South Africa. A combination of seven different treatments were used and included a weedy and weedfree treatment (these were imposed on plots where the plantation residues had been left in situ or alternatively burnt), a 2 m row weeding and the selective control of broadleaves or grasses only. Regardless of the treatment, tree growth suppression was detected where the vegetation was not controlled. However, the onset of competition occurred sooner and was much greater in the burnt + weedy (40 days after planting) treatment plots than in the unburnt + weedy plots (68 days after planting). Initial improvements in tree performance for those treatments where the vegetation was controlled was maintained over seven growing seasons, with significant differences recorded for the merchantable volume calculations. The best response, obtained with the unburnt + weedfree treatment, resulted in a 41% increase in merchantable volume when compared to the burnt + weedy treatment. No significant differences were detected between the residue management treatments when kept free of vegetation. Other benefits obtained from competition control include a reduced time to canopy closure and decreased stem variability.

In this paper, the dynamic change of tree height, DBH and stand volume in different density/spacing treatments, the relationship between DBH and crown width, the basic density management for 5.9-year old E. urophylla plantation in Laibin County of Guangxi, China, were studied. The results indicated that plantation density had a negative correlation with height, DBH and standing volume growth. The superiority order of the density treatments in stand volume was 1667>2222>3333 trees/ha. After 3.7 years, spacing 2 m × 3 m performed better in height growth than 1 m × 6 m. The best treatment was 1667 trees/ha with stand volume 2.04 times of that of 3333 trees/ha. Three spacing treatments ranked in stand volume in order: 1667>2222>3333 trees/ha at 4.7-year old but 2222>1667>3333 trees/ha at 5.9-year old. The treatment of density 2222 trees/ha yielded 127.6 m³/ha, 1.17 times as much as that of 3333 trees/ha. The relationship between crown width and DBH could be described as Cw=0.4724×DBH^0.6715. By means of the regression analysis, the basic density for E. urophylla plantations was developed, and the desirable planting spacing for E. urophylla pulp wood production was also suggested.

The eucalypt plantation forestry industry in China has expanded rapidly in the last decade. With this expansion, it is expected that pest and disease problems will increase. Devastating eucalypt pathogens already present in Asia include Phytophthora cinnamomi, Cryphonectria cubensis, Coniothyrium spp., Botryosphaeria spp., Mycosphaerella spp. and Cylindrocladium spp. There is an urgent need to train Chinese foresters and scientists to recognise eucalypt diseases and to establish a database for easy and rapid identification of disease problems. Good identification procedures in association with quarantine and breeding programs should help to reduce the impact of eucalypt diseases in Chinese plantations. This article gives an overview of the potential major threats to the Chinese eucalypt plantation industry and some strategies to manage disease incursions and their spread.

In June 1994, a typhoon (No.3) struck Leizhou Peninsula of Guangdong Province with a maximum wind speed of 32.6 m/s. This typhoon caused an average of 10-50% windfall and windbreak in young eucalypt plantation in Zhanjiang. Two spacing trials were investigated at three days and one month after the typhoon. Trees were scored according to 4 classes, based on the angle between stem and ground:.

A class=0 or stem break,.

B class=0-60, need to be recovered by hand,.

C class=60-90, most trees naturally recovered in 3 months, but growth was affected, and.

D class=no damage.

The results showed that the greater the planting density, the stronger the storm resistance. The percentage of trees scored A class in trial No.1 were 0.44%, 1.49% and 3.42%, and in B class were 2.20%, 5.33% and 12.14% for the spacing 3 m × 1 m, 3 m × 2 m and 3 m × 3 m, respectively. For the C class, more than 80% of trees had recovered within one month after the typhoon. The percentages of trees scored C class were 5.7%, 4.9% and 4.0%, respectively, one month after the typhoon. A two-year old eucalypt plantation was damaged by the typhoon more severely than the one-year old plantation. The percentages of trees scored A class in trial No.2 were 3.3% and 12.5%, and B class were 23.9% and 33.2% for 3 m × 1 m and 3 m × 2.5 m, respectively. Both spacing treatments of 3 m × 3 m and 3 m × 2.5 m were considered unsuitable for use in the coastal areas because of their heavy loss caused by typhoon.

Plantation-grown Eucalyptus, typically harvested when young, have wood properties distinctly different to those of trees of the same species harvested from Australia’s native forests. Characterisation of these wood properties is important. However, it can also lead to definition of utilization difficulties, occasionally a long list if higher-value utilization for lumber or plywood is intended. This paper does not dwell on the detail of such problems or their solution. Rather, it seeks to demonstrate the economic logic of overcoming them through the application of modern technology to produce new generation products. Thus, it is concerned with the utilization of plantation-grown Eucalyptus in the manufacture of such products as medium density fibreboard (MDF), oriented strand board (OSB) and laminate strand lumber (LSL). These are considered “sunrise” products, technically well suited to substitution for hardboard, particleboard, lumber and plywood in a wide variety of applications. Moreover, it is possible that they can be more cost-competitive than some of these “sunset” products.

The present work put together many results obtained from different research projects in order to give an overall view on the latest understanding on the improvement of wood yield and quality through forest improvement, management and sawing techniques. Sawn wood defects related traits like log end splitting, board end splitting and cupping are very heritable and selection of trees based on them brings enormous genetic gain. Therefore much of the gains provided by a well improvement and management program may get lost before or during sawing. Sawing strategy cannot be taken from one eucalypt species to another because the correlation between log end splitting and board end splitting depends on the forest stand performance and/or species. It is possible to predict board end splitting in Eucalyptus saligna and E. urophylla but not in most of the planted E. grandis. The system of sawing which permits doing balanced cuts in order to release growth stresses in an equilibrated way, allows for a higher productivity and better board thickness accuracy. Nevertheless, neither cant end splitting during the cut in the twin band saw nor end splitting in the board extremity during sawing in the gang saw can be avoided. Both board bow and crook cannot be avoided for any sawing strategies. No strong influence exists by the thinning intensity on those traits, which are smaller at the tree bottom.

Although the first Eucalyptus tree was introduced to Thailand and planted in Bangkok as an ornamental tree over one hundred years ago, a series of research on species and provenance trials for wood production was started in 1950. Most industrial plantations focusing on Eucalyptus camaldulensis for wood chips were begun less than twenty years ago. Demands of eucalypt log for wood-chip industry in the year 2002 for 3 main categories, i.e. pulp mills, chip mills and MDF, are 3,700,000 (57.86%), 2,015,000 (31.51%) and 680,000 tons (10.63%), respectively leading to the total demands of 6,395,000 GMT. Most private plantations set up rotation length at 5 years old with an average yield of about 75 tons/ha under proper establishment and maintenances. Thus, total plantation areas required for wood chips are 426,335 ha in order to be harvested 85,267 ha/yr.

In 1997, Thailand had 438,524 ha of eucalypt private plantations distributed 47.38 % in the Northeast, 28.73% in the East, 12.77% in the North, 11.07% in the Central Plains, and 0.05% in the South. New technologies were introduced to private plantations recently. Most planting stocks were produced from cutting, followed by tissue culture and seeds with the percentages of 80, 12, and 8, respectively. The spacing of 2 m × 3 m was a common practice planted after intensively mechanized site preparation. Some plantations preferred early dry-season planting in order to minimize the first-year weeding problems. Chemical fertilizers were applied periodically. Clearcutting with coppice system was carried out at 5 years old, followed by thinning the new shoots and remaining 2–3 sprouts for the next rotation.

LIST OF PARTICIPANTS.