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。     

Predicting the productivity of a young hybrid poplar clone under intensive plantation management in northern Alberta,Canada using soil and site characteristics

Site productivity of the hybrid poplar clone Brooks6 was predicted using soil and site information from 6, 4-year-old plantations in north-east Alberta. Predictions were made at both the local and microsite scales. Percent sand (R ² = 0.352, P = 0.001) was the best single predictor of hybrid poplar productivity, showing a curved relationship. Soil pH also showed a curved but weaker relationship with hybrid poplar productivity (R ² = 0.133, P = 0.100). Maximum tree productivity occurred at sand contents between 55 and 70% and pH values near 6. Other variables, including foliar nutrient concentrations, foliar δ¹³C, electrical conductivity, depth of the A horizon and total chemistry of the soil, were also related to hybrid poplar productivity at the local and microsite scales. However, all of these variables were correlated to either soil texture (percent sand) or pH. At the microsite scale within plantations, percent sand was the most important predictor of tree productivity and explained more than 50% of the variability within plantations, although the relationship varied by plantation. In plantations with fine textures, sandier microsites were associated with increased growth while in sandy plantations, finer textured microsites were more productive. As a whole, the growth of the hybrid poplar clone Brooks6 appears to be mostly influenced by a combination of soil water and nutrient availability, the former being impacted by soil texture and the latter being governed by soil pH.     

Effect of stand density and pruning on growth of ponderosa pines in NW Patagonia,Argentina

Due to the lack of knowledge about ponderosa pine performance under silvopastoral systems (SPS) conditions, the objective of this study was to determine the effect of stand density and pruning on the growth magnitude of ponderosa pines growing in NW Patagonia (SPS with 350 and 500 pines ha⁻¹ vs. commercial densities of 1,300 trees ha⁻¹, HPP). Individual growth rate was higher in SPS 350 trees than in SPS 500 trees, being both higher than in HPP plots, indicating a higher sensitivity of this drought resistance species to relative water availability. The higher individual growth compensated the lower amount of trees per land unit, being the whole stand growth similar or even higher in both SPS treatments than in the HPP stand. Pruning reduced diameter growth in both SPS treatments, at least until 2 years after pruning, with a more marked effect in the pruning treatment with the higher amount of extracted foliage. Carbon fixation reduction in addition to changes in carbon allocation within different plant parts after pruning could be the responsible of observed stem growth reductions. We suggest that higher growth rates in combination with frequent pruning in low density plantations can be applied to shorten the rotation period producing high quality timber in comparison with plantations managed under conventional conditions in Patagonia. Additional advantages could be associated to the lower environmental impact of low canopy cover plantations compared to high density stands.     

广东省桉树人工林生态问题评价

桉树是广东省人工造林的主要树种这一，并带来了十分显著的经济效益和社会效益。大面积桉树人工林存在着地力迅速消耗、水土流失、破坏林地水分平衡等问题，这主要是由于不适当的人为经营活动和一些外界因素所造成的。椐研究，桉树对水分和养分利用率是比较高的，由于生长量大，桉树对水分和养分的消耗量也较大，但桉树本身并不会产生不可逆转的生态危害。     

The effects of early and intense pruning on light penetration,tree growth,and epicormic shoot dynamics in a young hybrid larch stand

We examined the effect of early and intense pruning on light intensity under the canopy, individual growth, diameter–height relationships, and epicormic shoot dynamics in young hybrid larch (Larix gmelinii var. japonica × L. kaempferi) to establish a new effective management method for hybrid larch plantations. The objective is to produce high-quality wood while reducing silviculture costs using a combination of low-density planting and early and intense pruning. In a young hybrid larch plantation, we pruned branches to two different heights (2 and 4 m above ground level) using a no-pruning treatment as a control. Although the growth rates were lower in the heavy pruning treatment (4 m above the ground level) than in other treatments in the year following pruning, when measured 4 years later, growth did not differ between treatments. The number of epicormic shoots increased in the year following pruning, as did the relative photosynthetic photon flux density (rPPFD). The number of epicormic shoots was also dependent on the size of individual trees. However, survival of epicormic shoots was not sufficiently high to be problematic for high-quality timber production. If branches are pruned carefully such that the rPPFD does not rise above 20%, the emergence of epicormic shoots can also be controlled. Our results indicate that early and intense pruning is an effective component of a new management system for hybrid larch plantations.     

Effects of potassium/sodium fertilization and throughfall exclusion on growth patterns of Eucalyptus grandis W. Hill ex Maiden during extreme drought periods

New Forests - In Brazil, most Eucalyptus plantations are located in regions experiencing periods of water shortage where fertilizers are intensively used to achieve high productivity. Fertilization...     

桉树生态环境问题的研究现状及其可持续发展对策

为了探明桉树人工林的生态环境问题,在广西桉树主要种植区域内开展了连续10 a的定位监测研究。研究结果比较确切地回答了社会上有关桉树人工林生态环境争议的主要问题,并根据桉树经营过程中存在的主要问题,提出了相应的可持续发展对策。     

Applying PROMOD spatially across Tasmania with sensitivity analysis to screen for prospective Eucalyptus globulus plantation sites

When screening areas as prospective plantation sites two criteria are of interest: the expected yield at that site and the uncertainty associated with this yield expectation. This paper describes a methodology to enable spatial estimates of uncertainty to be attached to predictions of tree growth in relation to variations in soil depth, nutrient status, and drainage. An environmental sensitivity analysis was applied using the growth model PROMOD to produce site productivity and suitability maps for Eucalyptus globulus (Labill.) on a 1000 m regular grid of Tasmania. Nine productivity surfaces were computed, one for each of three assumed soil-water holding capacities (for soil depths of 0.5, 1.0, and 1.5 m — the common classes in Tasmania), combined with three permutations of soil-nutrient rating (the expected rating and one class above and one below this value), and incorporating potential waterlogging estimates. The mean and coefficient of variation was calculated for each 1000 m grid cell in the nine subsequent productivity surfaces. A final plantation suitability grid was then mapped to show areas of the State with predicted high (>25 m³ ha⁻¹per year), moderate (15–25 m³ ha⁻¹ per year), and low productivity (<15 m³ ha⁻¹ per year), each with corresponding high variability (coefficient of variation (CV>30%)) and low variability classes (CV<30%). As no areas had both, high productivity and high variability, only five plantation suitability classes were mapped.Those areas indicated as high productivity/low variation sites have a high probability of being successful E. globulus plantations. Low productivity sites with either high or low variation are very unlikely to be favourable for this species. Moderate productivity sites with low variation are likely to be viable potential plantation sites with relatively low risk, particularly with nutrient amelioration. Moderate productivity sites with high variation might warrant further field investigation to determine if there are major environmental factors or combinations of these, such as soil depth (water holding capacity), nutrient status, or drainage that are actually going to be limiting reasonable growth at these sites.     

马尾松、桉树及其混交林土壤养分变化特征及评价

研究马尾松纯林、桉树纯林和3种不同模式混交林土壤养分含量的变化规律,并对其土壤养分状况进行主成分综合排序。结果表明：土壤有机质、全 N、全 P、水解 N、速效 P 和速效 K 皆表现为随土壤深度增加而减少,全 K 则表现相反;在各林分中,桉树纯林的土壤有机质、速效 P 含量最高,混交林次之。混交林则土壤全 N、全P 和速效 N 含量总体上大于纯林。马尾松纯林除在浅层土中速效 P 含量最高外,其他养分指标都低于桉树纯林和混交林。土壤养分综合评价为桉树纯林＞混交林 A＞混交林 C＞混交林 B＞马尾松纯林,表现为桉树纯林养分状况最好,马尾松纯林最差,与针阔树种的生长特性和凋落物养分归还能力有关。混交林中种植密度较大的混交林A 养分状况相对较好,表明其养分储存能力较好,消耗较少。而相同种植密度下,混交林 C 的林分土壤养分状况优于混交林 B。     

The host range of the Eucalyptus Weevil, <Emphasis Type="Italic">Gonipterus “scutellatus”</Emphasis> Gyllenhal (Coleoptera: Curculionidae), in South Africa

• Introduction   

The Eucalyptus Weevil (Gonipterus “scutellatus” Gyllenhal) is a notorious pest of eucalypt plantations around the world, but its host range differs across its area of introduction, which may be due to it being a complex of several cryptic species.     

Wood‐rotting basidiomycetes are a minor component of fungal communities associated with Acacia hybrid trees grown for sawlogs in South Vietnam

Acacia hybrid (Acacia mangium × Acacia auriculiformis) clones are widely planted in Vietnam with a total of approximately 400,000 ha to meet the demand for pulpwood, sawn timber and wood chip exports. Silvicultural techniques such as pruning and thinning have been applied to improve productivity and sawlog quality of Acacia hybrid plantations. However, those techniques may also create opportunities for wood decay fungi to enter the Acacia hybrid stems through wounds and cause stem defects that reduce sawlog quality and the value of the plantation. The presence of fungal decay agents in Acacia hybrid trees was examined in two Vietnamese plantations. In July 2011, just prior to a second thinning, discoloured wood samples were taken from a three‐year‐old Acacia hybrid plantation at Phan Truong Hai for the isolation of fungi. In July 2012, approximately 18 months after pruning and thinning treatments, discoloured wood samples were taken from a three‐year‐old Acacia hybrid plantation at Nghia Trung for the isolation of fungi. DNA sequencing of the rDNA ITS identified the isolates. In May 2015, approximately 4 years after thinning and fertilizer treatments, discoloured and decayed wood samples were taken from the above (7‐year‐old) Acacia hybrid plantation at Phan Truong Hai for fungal identification. DNA was extracted directly from discoloured and decayed wood samples and fungal rDNA ITS amplicons sequenced on a Roche 454 sequencer. The results showed that silvicultural treatments did not affect the fungal communities associated with discoloured and decayed wood of Acacia hybrid plantation at Phan Truong Hai. A total of 135 fungal species or OTUs (operational taxonomic units) were identified, including 82 members of Ascomycota and 52 Basidiomycota.     

On-farm evaluation of two fast growing trees for biomass production for industrial use in Andhra Pradesh,Southern India

On-farm experiments were conducted in Khammam district of Andhra Pradesh from 2001 to 2006 to evaluate the biomass productivity, intercrop yields and profitability of Eucalyptus tereticornis clonal and Leucaena leucocephala variety K-636 based systems. Trees were planted at a spacing of 3 × 2 m and evaluated at three locations. Height growth was significantly higher in leucaena during the 4 year where as difference in diameter growth was not significant. Biomass partitioning to the bole was high in case of leucaena, ranged from 83% in 2.5–5 cm diameter at breast height (DBH) trees to 89% in 12.5–15 cm DBH trees and in eucalyptus clones the corresponding values were 71% in 2.5–5 cm DBH trees and 83% in 12.5–15 cm DBH trees. Marketable biomass productivity was higher with leucaena (95 Mg ha⁻¹) in comparison to eucalyptus (87 Mg ha⁻¹). Competition effects of trees on intercrops were observed from the 2 year (2002 post-rainy season). Intercrop yields were 45% of the sole crop in eucalyptus system and 36% in leucaena system during the 2 year. Sole eucalyptus and leucaena plantations and intercropping systems recorded higher gross and net returns over arable cropping. Therefore, it can be concluded that leucaena variety K636 and eucalyptus clonal based agroforestry systems are profitable alternatives to arable cropping under rainfed conditions.     

西澳州桉树林地土壤菌根菌剂接种潜力研究(英文)

对澳大利亚西澳州桉树人工林菌根类型及其形成情况进行了调查 ,并采用生物测定法 (Bioas saymeasurement)研究了桉树林地土壤菌根菌剂的接种潜力 .根系菌根检查和生物测定法试验均表明 ,在自然条件下桉树可以和不同真菌共生而形成三种类型的菌根 ,即外生菌根、VA菌根和混合菌根 ;林分成熟程度与菌根形成有一定的相关性 ,与共生体的类型也有一定影响 .在幼林中 ,桉树根系主要与内囊霉菌共生形成VA菌根 ,而成熟林主要与担子菌共生形成外生菌根 ,混合菌根表现为一种中间类型 .在收集的林地土壤中移植的菌根诱饵植物 (三叶草和蓝桉 )分别检测出土壤中存在有一定量的VA菌根菌和外生菌根菌 ,但菌根菌繁殖体数量及接种潜力相对较小 ,并且也揭示了按树年龄对土壤菌剂的相对接种潜力影响较大 .本文对桉树人工林土壤菌剂接种潜力进行了评价 ,并就引进优良菌根菌对桉树人工林生产的重要性进行讨论     

论中国桉树发展的贡献和可持续经营策略

我国最早于1890年引进桉树,刚开始主要作为庭院和四旁绿化树种,20世纪50年代在粤西和桂南大面积试种成功后,逐步推广作为南方主要造林树种.20世纪80年代,我国开始大规模种植桉树,1986年,全国桉树人工林面积达46.6万hm2,进入21世纪后,桉树发展迅猛,2015年达450万hm2,年产木材3000万m3,占全国商品林木材产量的26.9％,为保障我国木材安全做出了重要贡献.桉树产业已形成包括种苗、肥料、制材、制浆造纸、人造板、生物质能源和林副产品等完整的产业链,年总产值达3000亿元.发展桉树人工林具有非常重要的意义:一是缓解我国木材供应紧张局面,减少对外依存度,以保障国家木材安全;二是桉树产业已形成完整的产业链,构成国民经济不可或缺的一部分;三是对提高森林碳汇、发挥气候调节、完善森林的生态和防护功能具有重要意义;四是重要的民生林业,促进林农增收和农村致富.桉树科学发展的关键在于可持续经营.首先必须更新观念:由木材生产为主向木材生产与环境保护并重转化,由封闭式经营向开放式经营转化,由传统的永续利用向森林可持续经营转化.同时,必须推行以下可持续经营的技术措施:(1)立地与树种、品种相匹配;(2)适当的人工混交林措施;(3)进行科学的植被管理;(4)改进造林技术;(5)控制病虫害.     

Host range of Erwinia psidii and genetic resistance of Eucalyptus and Corymbia species to this pathogen

Dieback caused by Erwinia psidii is currently one of the most important emerging diseases in eucalypt plantations in Brazil. However, little is known in terms of the host range of this pathogen or the potential sources of resistance against the disease it causes. In this study, we inoculated plants of species from nine families to gain insight into the host range of E. psidii. Plants of all inoculated species of Myrtaceae except Acca sellowiana exhibited disease symptoms and therefore represent potential hosts for the pathogen under natural conditions. In addition, the response of four Corymbia species, 29 Eucalyptus species and three interspecific Eucalyptus hybrids to inoculation with E. psidii was evaluated. All Corymbia henryi, Corymbia maculata, Eucalyptus thozetiana, Eucalyptus cloeziana, Eucalyptus viminalis, Eucalyptus dalrympleana and Eucalyptus pilularis plants were highly resistant to the pathogen, whereas differential disease resistance was observed in the other species. This study provides important information on sources of resistance to Erwinia psidii with potential use in the development of clones with enhanced resistance in eucalypt species of economic importance.     

A weeding-duration model for <Emphasis Type="Italic">Larix kaempferi</Emphasis> plantations in Hokkaido,northern Japan

In this study, a weeding-duration model for Larix kaempferi plantations was developed that employs a generalized linear model. The number of years that weeding is necessary is the response variable, and elevation, slope, maximum snow depth, annual precipitation, geological type, soil type, site index, slope aspect, and vegetation type are explanatory variables. Among the explanatory variables, geological type, soil type, slope aspect, and vegetation type are categorical data. We assumed a Poisson distribution for the response variable. The link function was log. Among the models that could be developed from these variables, we chose the model with the smallest Akaike’s information criterion (AIC). The weeding-duration model can be written as follows: years that weeding is necessary = Exp (−0.0172833 × site index + 0.0014053 × maximum snow depth (cm) + 1.7417731). The results of this study imply that weeding of Larix kaempferi plantations is needed for more years as the maximum snow depth increases and fewer years as the site index increases. This model is useful for cost–benefit analyses of afforestation or reforestation with Larix kaempferi.     

Effect of pruning frequency and pruning height on the biomass production of <Emphasis Type="Italic">Tithonia diversifolia</Emphasis> (Hemsl) A. Gray

Addition of tree or shrub prunings through alley cropping or biomass transfer systems have contributed to sustainable land-use systems in the tropics. Long term productivity of biomass transfer systems require shrub or tree species that coppice after cutting to provide sufficient plant nutrients. The effect of pruning frequency and cutting height on the biomass production of Tithonia diversifolia was studied to provide information for managing hedges. Results showed that height of cutting, pruning frequency, and their interactions significantly affected dry matter production of T. diversifolia. The results also showed that a significantly higher biomass production could be produced when Tithonia was pruned at long time intervals. Pruning height was also of importance in the harvesting of Tithonia biomass and it was evident that dry matter production was highest when Tithonia was pruned bimonthly at 50 cm height. With bi-monthly pruning frequency, dry matter production could be as high as 7.2 t ha⁻¹ yr⁻¹ which might be a sufficient biomass to improve soil productivity in biomass transfer systems.     

Ecophysiological acclimatization to cyclic water stress in Eucalyptus

Drought is considered the main environmental factor limiting productivity in eucalyptus plantations in Brazil. However, recent studies have reported that exposure to water deficit conditions enables plants to respond to subsequent stresses. Thus, this study investigates the ecophysiological acclimatization of eucalyptus clones submitted to recurrent water deficit cycles. Eucalyptus seedlings were submitted to three recurrent water deficit cycles and anatomical, morphological and physiological changes were analyzed. The results were:(1) Eucalyptus seedlings responded to water deficits by directing carbohydrates to root and stem growth;(2) Size and number of stomata were reduced;(3) Stomatal conductance decreased which allowed the plants to reduce water losses through transpiration,increasing instantaneous water use efficiency;(4) The relationship between gas exchanges and available water contents allowed the seedlings to uptake the retained soil water athigher tensions;and,(5) Physiological recovery from subsequent water deficits became faster. As a result of these changes, the eucalyptus seedlings recovered from the same degree of water stress more rapidly.     

Effect of pruning Acacia mangium on growth,form and heart rot

Small volumes of timber are now being produced from Acacia mangium plantations in Indonesia. These trees require pruning and thinning to increase the strength and appearance of the wood. However, cut surfaces from pruning are potential infection courts for the entry of decay-causing fungi like heart rot. This study investigated the effects of pruning on stem form and the incidence of heart rot in an 18-month-old plantation of Acacia mangium in South Sumatra. The objectives were to assess whether pruning is associated with an increase in the incidence of heart rot and whether form pruning compared to lift pruning reduced the incidence of heart rot and improved stem form. Form pruning removed 25% of leaf area by removing large branches and those subtending a narrow angle with the stem up to 3 m height, and lift pruning removed 25% of crown length from below. Trees in these treatments were singled before pruning. The third treatment, a control, was not singled and was used to assess base levels of heart rot.No significant difference in diameter increment between the two pruning treatments was found. There was strong evidence that form pruning was associated with better form 18 months after treatment. Trees in this treatment had a reduced number of branches >30 mm diameter and improved stem straightness (reduced kink). Lift pruning reduced average branch size but did not improve stem straightness. No heart rot was detected in any treatment.The results showed that form pruning is likely to have positive benefits on stem straightness and is likely to be effective to any selected pruning height. However a subsequent lift pruning is still considered a requirement. While wounds created from pruning and singling are assumed to have a large impact on the incidence of heart rot, this may not be an issue unless there is a sufficient source of fungi present in the environment to invade the wounds.