The coppice-with-standards silvicultural system as applied to Eucalyptus plantations — a review

We review the management of Eucalyptus species under a coppice-with-standards （CWS） silvicultural system. CWS management results in product diversification, permitting production of small and large scale timber from the same stand. Eucalyptus species are suitable candidates for CWS management because： there are large worldwide plantation areas, sprouting capacity is high, and eucalypts are multipur- pose species. We discuss （1） short rotation Eucalyptus coppice manage- ment for energy and pulping and （2） Eucalyptus seedling management for solid wood products. We review the literature and discuss experi- ences with Eucalyptus managed under the CWS system. We also assess projects dealing with Eucalyptus coppice management, stand density regulation, pruning, and stand and wood quality. The growth environ- ment of the standard trees （heavy competition up to the first harvest, free growth afterwards） coupled with long rotations （〉20 years） results in high quality logs for solid wood products. Early pruning should be ap- plied to enhance wood quality. We propose a system for the silvicultural management of Eucalyptus under the CWS system, elaborating on the consequences of initial planting density, site productivity, and standard tree densities as well as timing of basic silvicultural applications.     

Neotropical small mammals’ diversity in the early cycle of commercial Eucalyptus plantations

Studies carried out in Brazil revealed that Eucalyptus plantations shelter numerous species of small-size non-flying mammals. However, their distribution pattern inside the Eucalyptus plantations remains unknown. This study aimed at the identification of possible influence of distances from the remaining native revegetation areas and riparian systems, on spatial distribution and abundance of small-size mammals in Eucalyptus plantations. This study was carried at Eucalyptus stands recently planted (0–3 years) at the municipality of Angatuba, Sao Paulo state, Brazil between August 2007 and July 2009. The survey was carried out using pitfall traps at 14 sampling units inside Eucalyptus plantations 60–1130 m away from the borders. With a sampling effort of 2,449 bucket night, the experiment captured 680 individuals belonging to 12 species of small-size mammals (rodents and marsupials). The colonization process of Eucalyptus plantations was apparently initiated by generalist species from open Cerrado. In the present study, we did not find any clear correlation between specific richness and abundance of individuals and the distance from native revegetation areas or closer riparian systems. The study suggests that Eucalyptus plantations are permeable matrices to, at least, more generalist species present in the silvicultural landscapes (i.e. composed by an Eucalyptus plantation as the matrix and native vegetation patches). However, further studies must prioritize analyzing the influence of agricultural/sivilcultural practices (e.g., plantation structure and harvest frequency) on habitat quality and carrying capacity of agricultural/silvicultural landscape matrices, as well as implementing long-term monitoring programs to assess the impact of complete production cycles (some years) and along cycles of Eucalyptus plantations (some decades), on rodents population’s diversity and dynamics patterns.     

Effect of silvicultural practices on fibre properties of Eucalyptus wood from short-rotation plantations

The effect of nitrogen addition and weed management on fibre properties of wood from 6.5-year-old Eucalyptus grandis and E. tereticornis from intensively managed short-rotation plantations were investigated. Trees for analyses were sampled from plots with zero nitrogen input (n = 4), plots with high level (187 kg N ha^?1) nitrogen input (n = 4), plots from which weed growth was not removed throughout the rotation (n = 4) and plots from which weeds were removed periodically (n = 4). Fibre characteristics were evaluated on wood samples collected from base, breast height, 50, 75 and 100 % of merchantable bole height of trees. Though N input and weed management improved tree growth significantly irrespective of species, the treatment effects did not cause any significant change in fibre characteristics such as fibre length, fibre diameter, lumen width and wall thickness. Longest and widest fibres were observed at the outer most radial portion of wood in all cases. In general, within tree fibre length varied significantly along the radial direction of wood. Fibre diameter, lumen width and wall thickness lacked any specific pattern between species and treatments. Runkel ratio and felting and flexibility coefficients values showed high pulping quality of wood irrespective of species and treatments. The study concluded that the fibre properties that influence pulpwood quality of Eucalyptus have not been affected by silvicultural practices, like fertilizer input and weed management, aimed at improving productivity of short-rotation eucalypt plantations.     

A review of heartwood properties of Tectona grandis trees from fast-growth plantations

Teak (Tectona grandis L. f) has been introduced to reforestation programs in many tropical countries for timber production. The use of teak plantations has changed the supply from large-diameter logs to small-diameter logs featuring a higher proportion of juvenile wood and more knots. Generally, the teak from fast-growth plantation is harvested after 15–30 years of growth, with logs ranging from 12 to 30 cm in diameter. The goal of this work was to review the factors that influence the heartwood formation, variation, quality, color, and durability in teak and to understand which factors should be controlled in fast-growth plantations. Important factors in the heartwood properties of teak trees from fast-growth plantations are as follows: the tree age, longitudinal variation, geographic location, environmental conditions, and silvicultural activities. These factors influence heartwood extractive content, color variation, and durability.     

桉树大径材培育技术研究概述

培育大径材用于实木加工是桉树人工林发展的趋势,但桉树人工林大径级原木的培育尚缺乏经验。本文综述了国内外在桉树大径材树种选择、初植密度控制、间伐、修枝和施肥管理方面的现状及其对大径材生长和材性的影响,以期为桉树资源高效利用及大径材人工林的可持续发展提供借鉴和依据。     

Stand Density Management Diagrams for Three Exotic Tree Species in Smallholder Plantations in Vietnam

When smallholder farmers establish tree plantations to sell wood to the wood industry, they may run into problems when the plantations are mature and to be marketed because these farmers usually (1) do not know how to estimate the growing stock and (2) do not have sufficient knowledge of the wood markets. In this study, we tackle problem (1) and present stand density management diagrams (SDMDs) as a simple tool that allows rapid estimation of standing volume from data that stem from very basic inventory. Our data come from smallholder plantations in Vietnam, from four communes in the provinces of Binh Dinh and Phu Tho. Immense afforestation activities have been taken place in the country during the past two decades and it is special to Vietnam that a large share of these afforestations are under smallholder management with the goal to generate an additional source of income for these rural poor. A certain type of SDMDs is elaborated for three important exotic tree species commonly used for establishing industrial tree plantations (Acacia hybrid, Acacia mangium and Eucalyptus urophylla). They can be used for volume estimation and are also a tool to guide stand management and silvicultural treatments in general. Both implementation of the inventory and usage of the SDMDs are straightforward and simple so that this tool may be well suited to support smallholders in a better informed marketing of their wood, as well as, a better informed silvicultural management of their plantations.     

Effects of the lateral growth rate on wood quality of Gmelina arborea from 3.5-, 7- and 12-year-old plantations

? Awareness of the shortage of fossil resources leads to an increasing demand for woody biomass. We investigated the feasibility of using fast-growing Gmelina arborea wood for material production. Gmelina arborea wood samples were collected from trees of varying cambium ages in Indonesia, from 3.5-, 7- and 12-year-old plantations.

? The lateral growth rate and the cambium age did not significantly affect the longitudinal released strain of the growth stress, xylem density, or microfibril angle at the outermost surface of the secondary xylem at any sampling site. However, fiber length in the 3.5-year-old plantation tended to be shorter in smaller diameter trees, whereas in larger diameter trees it was almost the same as that in trees from the 7- and 12-year-old plantations. This suggests that smaller diameter trees in the 3.5-year-old plantation had not yet produced mature wood.

? Xylem qualities had already reached values appropriate for harvesting, except in the smaller diameter trees from the 3.5-year-old plantation. This indicates that the larger diameter trees had already matured, regardless of their cambium age. These results suggest that the next step is to develop silvicultural treatments to increase the lateral growth rate during the early growing stage, in order to produce as much mature wood as possible, as quickly as possible.

     

桉树木材皱缩形成机制与调控研究进展

文章综述了近年来国内外学者对桉树木材皱缩形成机制的研究进展, 分析了可有效防止木材皱缩的后期调湿处理、热处理、加压或拉伸处理以及预冻处理等主要预处理方法对减少木材皱缩的作用, 展望了今后木材皱缩研究的发展趋势, 以期为我国桉树人工林资源高附加值利用提供参考。     

Early assessment of density features for 19 Eucalyptus species using X-ray microdensitometry in a perspective of potential biomass production

Eucalyptus plantations have been considered for bioenergy production and hence their biological characteristics that make them amenable to intensive short-rotation forestry. Wood density is an important parameter that directly affects fuel production. This study focuses on the early assessment of density features for 19 Eucalyptus species using X-ray microdensitometry in a perspective of potential biomass production. Average ring density, earlywood density, latewood density, latewood percentage and the heterogeneity index were studied. E. polyanthemos registered the highest mean wood density value (0.84 g cm^?3), and E. viminalis showed the lowest value (0.53 g cm^?3). An indicator for the potential wood biomass (PWB) was calculated, with E. maculata displaying the highest biomass production index (13.4 kg). Comparison of radial growth of these species showed appreciable differences. The PWB indicator points to the prospective good aptitude for short-rotation cycle for biomass production of E. maculata, E. botryoides, E. globulus, E. nitens and E. sideroxylon.     

Financial appraisal for some afforestation species in Bihar (India) under the risk of illicit felling

The major afforestation schemes in the state of Bihar (India) consist of the coppicing of the degenerated natural forests and/or raising plantations of various species at a spacing of 2 m × 2 m. Shorea robusta is the main species of the natural forests whereas Eucalyptus hybrid and Dalbergia sissoo are the two main plantation species. This paper sets out to undertake a detailed financial cost-benefit analysis for the three species separately and discusses some management options regarding the choice of rotation for each species under the risk of illicit felling. Three quality classes—I, II and III—have been considered separately for all the three species. The yield of the plantations of Dalbergia sissoo and Eucalyptus hybrid for a spacing of 2 m × 2 m, hitherto subject to value judgements, have been estimated using the regression model for variable stocking density. The net present value per hectare has been selected as the criterion for appraisal and its value for the three species for the management options considered has been calculated for one rotation as well as for an infinite series of rotations. The risk of illicit felling has been accounted for by adding a premium to the pure temporal discount rate. The paper shows that for a given species the best management option would be different for different quality classes. In general, plantations in quality class I are viable, but for quality classes II and III plantations are worth undertaking only if the illicit felling is reasonably under control to justify low discount rates.     

Growth and stem quality responses to fertilizer application by 21 loblolly pine clones in the Virginia Piedmont

Clonal forestry offers the opportunity to increase yields, enhance uniformity and improve wood characteristics. Intensive silvicultural practices, including fertilization, will be required to capture the full growth potential of clonal plantations. However, variation in nutrient use efficiency that exists among clones could affect growth responses. Our research objective was to determine the range of growth response and stem form quality due to fertilization in clones of Pinus taeda. A split-plot experimental design was used, with the whole plots being two levels of fertilizer application (fertilizer versus control) and the split plot factor being 25 clones. Whole plot treatments were blocked and replicated four times. Six years after planting and five years after fertilizer application, a repeated measures analysis showed fertilizer-by-time and clone-by-time interactions affected volume (p < 0.10). Clone-by-fertilizer interactions were observed for tree height, branch traits, and a metric of foliar display. These interactions were primarily due to scale-effect phenomena rather than rank shifts. The magnitude of fertilizer responses observed in a small number of genotypes suggests that knowledge of fertilizer responses in widely deployed genotypes, if developed prior to mid-rotation, may better optimize management of single-clone blocks. Our results further indicate that a range of possibilities exist for the design and application of clone-specific precision silvicultural systems.     

Biogeochemical cycles of nutrients in tropical Eucalyptus plantations: Main features shown by intensive monitoring in Congo and Brazil

The sustainability of fast-growing tropical Eucalyptus plantations is of concern in a context of rising fertilizer costs, since large amounts of nutrients are removed with biomass every 6–7 years from highly weathered soils. A better understanding of the dynamics of tree requirements is required to match fertilization regimes to the availability of each nutrient in the soil. The nutrition of Eucalyptus plantations has been intensively investigated and many studies have focused on specific fluxes in the biogeochemical cycles of nutrients. However, studies dealing with complete cycles are scarce for the Tropics. The objective of this paper was to compare these cycles for Eucalyptus plantations in Congo and Brazil, with contrasting climates, soil properties, and management practices.The main features were similar in the two situations. Most nutrient fluxes were driven by crown establishment the two first years after planting and total biomass production thereafter. These forests were characterized by huge nutrient requirements: 155, 10, 52, 55 and 23 kg ha^?1 of N, P, K, Ca and Mg the first year after planting at the Brazilian study site, respectively. High growth rates the first months after planting were essential to take advantage of the large amounts of nutrients released into the soil solutions by organic matter mineralization after harvesting. This study highlighted the predominant role of biological and biochemical cycles over the geochemical cycle of nutrients in tropical Eucalyptus plantations and indicated the prime importance of carefully managing organic matter in these soils. Limited nutrient losses through deep drainage after clear-cutting in the sandy soils of the two study sites showed the remarkable efficiency of Eucalyptus trees in keeping limited nutrient pools within the ecosystem, even after major disturbances. Nutrient input–output budgets suggested that Eucalyptus plantations take advantage of soil fertility inherited from previous land uses and that long-term sustainability will require an increase in the inputs of certain nutrients.     

Assessing the effects of early silvicultural management on long-term site productivity of fast-growing eucalypt plantations: the Brazilian experience

Eucalyptus is the dominant and most productive planted forest in Brazil, covering around 3.4 million ha for the production of charcoal, pulp, sawtimber, timber plates, wood foils, plywood and for building purposes. At the early establishment of the forest plantations, during the second half of the 1960s, the eucalypt yield was 10 m³ ha^?1 y^?1. Now, as a result of investments in research and technology, the average productivity is 38 m³ ha^?1 y^?1. The productivity restrictions are related to the following environmental factors, in order of importance: water deficits > nutrient deficiency > soil depth and strength. The clonal forests have been fundamental in sites with larger water and nutrient restrictions, where they out-perform those established from traditional seed-based planting stock. When the environmental limitations are small the productivities of plantations based on clones or seeds appear to be similar. In the long term there are risks to sustainability, because of the low fertility and low reserves of primary minerals in the soils, which are, commonly, loamy and clayey oxisols and ultisols. Usually, a decline of soil quality is caused by management that does not conserve soil and site resources, damages soil physical and chemical characteristics, and insufficient or unbalanced fertiliser management. The problem is more serious when fast-growing genotypes are planted, which have a high nutrient demand and uptake capacity, and therefore high nutrient output through harvesting. The need to mobilise less soil by providing more cover and protection, reduce the nutrient and organic matter losses, preserve crucial physical properties as permeability (root growth, infiltration and aeration), improve weed control and reduce costs has led to a progressive increase in the use of minimum cultivation practices during the last 20 years, which has been accepted as a good alternative to keep or increase site quality in the long term. In this paper we provide a synthesis and critical appraisal of the research results and practical implications of early silvicultural management on long-term site productivity of fast-growing eucalypt plantations arising from the Brazilian context.     

Comparative study on growth,wood quality and financial returns of teak (Tectona grandis L.f.) managed under three different agroforestry practices

Growth, wood quality parameters and productivity estimations of 12-year-old teak (Tectona grandis L.f.) grown under three agroforestry systems, namely unmanaged block (B_um), unmanaged line on the farm boundary (L_um) and intensively managed block (B_im) plantations are studied. Mean annual increment (MAI) of 0.020, 0.006 and 0.016 m³ tree^?1 year^?1 was recorded in L_um, B_um and B_im, respectively. Overall growth performance of teak raised in L_um, plantation appears to be better than two block plantations (B_um and B_im). For evaluating various wood quality parameters, tree logs from each plantation were tested for different physical and mechanical properties according to the standard procedures. The wood quality of B_um was found to be comparatively superior to B_im and much better than those of L_um. The 12-year-old farm teak trees from three systems exhibited lower average values of different wood quality parameters compared to mature forest teak. Since physical and strength properties of B_um were inferior compared to L_um and B_im, its exploitation is not advisable at this stage. Line plantation, however, releases land for cultivation of arable crops and does not demand any special silvicultural management as required by B_im. Although, total extractable volume of teak wood available after 12-years of age from B_um was much smaller compared to B_im or L_um, its commercial exploitation at an early age may be preferred over other two practices due to better wood quality and lower management cost. For optimum economic utilization and mechanical maturity of wood, harvesting of block plantation may be delayed for about 10-15 years because growth volume and strength properties are expected to improve with age of tree.     

Does reverse growth dominance develop in old plantations of Eucalyptus saligna?

Patterns of stand growth and dominance among individual trees change through stand development. We tested a prediction that large, old plantations of Eucalyptus saligna (Sm.) in Hawaii and Brazil would show a pattern of “reverse” growth dominance, with the largest trees contributing more to stand biomass than to current stand increment. This pattern might develop if the largest trees accounted for a large portion of the total resource use of the stand, but were less efficient at utilizing resources to produce stemwood. The 70-year-old plantation in Hawaii had a stem mass of 610 Mg/ha, compared with 325 Mg/ha in the 66-year-old Brazil plantation. Cumulative frequency plots for both sites showed that dominant trees comprised a very large proportion of total stand mass; the largest 20% of the trees accounted for 50% and 30% of the total stand mass in Hawaii and Brazil, respectively. Contrary to expectations, the largest trees continued to produce a disproportionately large amount of total stand growth, with the largest 20% of trees accounting for 60% (Hawaii) and 40% (Brazil) of stand growth. The frequency distributions resulted in positive growth dominance coefficients (similar to Gini coefficients) of 0.14 for Hawaii and 0.09 for Brazil, rather than negative values that would indicate that reverse growth dominance. The failure of these monoculture Eucalyptus stands to develop reverse growth dominance contrasts starkly with a variety of studies with pine species, which tend to show neutral-to-reverse growth dominance. Indeed, continued dominance of large trees suggests the trees might respond well to silvicultural treatments such as thinning or fertilization. Future work that contrasts patterns of growth dominance among species will be important as a foundation for developing generalizations about trends in growth dominance with stand development.     

Relationships between nursery practices and field performance for Eucalyptus plantations in Brazil

The 3.5 million ha of Eucalyptus plantations in Brazil support many domestic and industrial activities. In the pulpwood sector, forest productivity has increased from 12 to 40 m³ ha^–1 year^–1 through breeding and silviculturalpractices. Nurseries have fostered thisevolution with changes in container/substratetypes, propagation methods and specificinfrastructure for each plant growth phase.Eucalyptus plants are mainly produced bycuttings, using rigid tube containers filledwith vermiculite-organic compound substrates.Stock quality is based on morphologicalcharacteristics of the plants, andenvironmental conditions are highly significantfor plant performance. Performance is dependenton physiological short-term effects related tosurvival and long-term effects of genotype/rootmorphology related to tree development. Currentsilvicultural trends are reducing establishmentcosts but increasing the risk of using lowquality plants. The development of fieldperformance models and nursery physiologicaltests is recommended for Eucalyptusplantations in Brazil. Improved experimentaldesigns are needed to capture the interactionbetween plant quality and field performance.     

A Synthesis of the Available Evidence to Guide the Design of Mixed-Species Forest Plantings for Smallholder and Community Forestry

There is growing interest in using multi-species plantation systems when undertaking reforestation for timber production. Such plantations can have ecological and socio-economic advantages over those of traditional monocultures. Despite increasing evidence about the functional advantages of increasing species richness in reforestation, there are few silvicultural guidelines to assist in the design and management of multi-species plantings. This paper presents the results of a systematic assessment of previous studies of mixed-species plantings with a particular focus on their advantages and disadvantages for meeting the needs of rural smallholders and communities in tropical regions. Research on mixed-species plantations has increased in recent years. Many earlier studies were concerned with the capacity of mixed-species plantings to improve productivity or the nutritional impacts of mixtures. Many of these studies emphasised young plantations and mixtures of a few relatively fast-growing Acacia, Eucalyptus and Pinus species. More recent studies have explored a wider range of outcomes arising from using mixtures including on the supply of ecosystem services. Issues deserving further study concern the economic advantages or disadvantages of mixed-species plantations, how these plantations might be designed to suit various environmental and socio-economic situations, and how to manage older mixed-species plantations where the interactions between species may be different to those in younger plantations. There is also a need to explore how increased species richness may affect the capacity of new plantations to withstand damage from insect pests or disturbances such as storms or wildfire.     

Effects of the lateral growth rate on wood quality parameters of Eucalyptus grandis from different latitudes in Brazil and Argentina

Climate change resulting from increased atmospheric carbon dioxide (CO₂) and shortages of fossil fuels such as petroleum are major problems worldwide. Under these conditions, demand for woody biomass resources is increasing. We investigated the feasibility of using fast-growing Eucalyptus grandis for material production. Samples of E. grandis were collected from four plantations in different latitude divisions, including tropical and subtropical Brazil and subtropical Argentina. Various xylem qualities were measured and related to the lateral growth rate. Lateral growth rate did not significantly affect the longitudinal released strain of the surface growth stresses or the xylem density at any of the sampling sites. Higher lateral growth rate, higher values of xylem density, and lower absolute values of the released strain were observed in plantations closer to the equator. Higher growth rates in tropical climate promote longer fiber length. In subtropical plantations, smaller diameter trees will produce tension wood with smaller microfibril angles. Planting E. grandis closer to the equator thus produces higher quality wood than in plantations at lower latitudes.     

Factors controlling Eucalyptus productivity: How water availability and stand structure alter production and carbon allocation

Wood production varies substantially with resource availability, and the variation in wood production can result from several mechanisms: increased photosynthesis, and changes in partitioning of photosynthesis to wood production, belowground flux, foliage production or respiration. An understanding of the mechanistic basis for patterns in wood production within a stand and across landscapes requires a complete annual carbon budget. We measured annual carbon flows to wood production, foliage production and total belowground carbon flux (the sum of root production, root respiration, and mycorrhizal production and respiration) from ages three to five years in clonal Eucalyptus plantations at four sites in Brazil to test if fertility, water availability and stand structure changed wood production and by what mechanism. We also quantified the patterns in light interception and the efficiency of light use to provide additional mechanistic insights into growth responses and to determine if light-use efficiency was related to changes in flux and partitioning.     

Multiple rotation yields for intensively managed plantations in the Amazon basin

Jari Celulose S. A. is a Brazilian-owned industrial enterprise located along the Jari River (the first major south-flowing tributary of the Amazon). The company produces bleached kraft pulp for international and domestic sales. The raw material of this pulp production comes from the 75,000 ha of intensively managed plantations of Pinus caribaea (Morelet) and Eucalyptus spp. harvested on 10- and 6-year rotations, respectively. All currently active Jari plantations were converted from primary forest between 1968 and 1982. Silvicultural practices have been modified over successive rotations, including plantation species changes, increased intensity of site preparation, fertilization, and chemical weed control. A review of data from the early 1970s to present indicates an increase in productivity over successive rotations and several plantation locations and soil types. The reasons for this improvement are primarily related to the higher levels of silvicultural inputs and dramatic genetic gains. The long-term sustainability of this productivity is discussed in terms of current and future inputs. This revised version was published online in June 2006 with corrections to the Cover Date.