Eucalypt pests and diseases: growing threats to plantation productivity

Plantations of eucalypts (species of Eucalyptus and Corymbia), particularly in the tropics and Southern Hemisphere, have expanded dramatically during the course of the last 100 years. The nature of these plantations has changed substantially as selection, breeding, hybridisation, vegetative propagation and other innovative techniques have been introduced to improve planting stock. Although there are various examples of diseases and pests damaging early plantations, it is clear that separation of the trees from their natural enemies has resulted in exceptional performance. Not surprisingly, both the incidence and impact of diseases and pests in eucalypt plantations has increased over time. This has been due to the accidental introduction of pests and pathogens from areas where the trees are native to new environments. There are also growing examples of host-specific pathogens native to areas where eucalypts have been planted as non-natives, which have undergone sometimes surprising host jumps. These 'new pathogens' threaten not only plantation forestry based on non-natives, but also eucalypts and their relatives in areas where they grow naturally. There is little question that pests and pathogens are set to challenge eucalypt plantation forestry worldwide, more than ever before. In order to sustain profitable businesses based on eucalypt plantations, forestry companies will need to invest substantially in technologies enabling management of these pests and diseases.     

Diseases of eucalypts in the central and northern provinces of Mozambique

In the mid-1970s, Mozambique embarked on several forestry projects to promote and establish large plantation areas with eucalypt trees. The planted species included Corymbia citriodora, Eucalyptus camaldulensis, E. saligna and E. tereticornis. Similar to other regions of the world, pests and pathogens pose a significant threat to eucalypt plantations in Mozambique, but little is known regarding the diseases of trees in the country. The aim of this study was to provide the first detailed consideration of the possible disease problems affecting plantation- grown eucalypt species in the central and northern provinces of Mozambique. Isolates of fungal pathogens were obtained from material displaying disease symptoms collected during two field surveys conducted in 2010 and 2011. Representative fungal isolates were identified using DNA sequence data. Stem canker diseases caused by fungi in the Botryosphaeriaceae, Cryphonectriaceae and Teratosphaeriaceae, as well as leaf spots caused by species of Calonectria, Pilidiella, Pilidium and Phakopsora myrtacearum were commonly encountered. Their relative importance to the future of planation forestry in Mozambique is discussed.     

我国环北部湾地区发展桉树的思考

我国北部湾地区具有独特的地理位置和良好的自然条件,是我国桉树造林较早、种植面积大、桉树产业发展最快的地区,形成了从育苗、造林到加工利用的完整产业链;我国以桉树为原材料的大型林浆纸项目基本上都集中于此,为我国桉树产业及林产业重要的发展区域。文中综述了该地区桉树发展历程与现状,指出了桉树人工林发展中存在的一些问题,提出了桉树人工林可持续经营建议和策略,以期为进一步提高该地区桉树人工林产量与质量、优化生态环境和发展我国桉树产业提供决策参考。     

桉树人工林风险分析与可持续经营研究——以“永林公司”经营区为例

桉树是我国南方最重要的人工林树种之一,因具有广泛的适应性而得到大力发展,已成为我国林业史上引种最为成功的树种之一,也是永林公司主要造林树种。因此,本文以永林公司经营区桉树人工林为例,在深入进行桉树引种风险分析的基础上,建立了桉树人工林可持续经营技术措施体系,从而为永林公司桉树人工林可持续经营提供了有力的技术保障,也为我国桉树可持续发展提供了参考。     

提倡绿色作业，促进桉树可持续发展

桉树人工林的飞速发展,为国家经济和林业发展做出了重大贡献。因部分经营者缺乏森林生态经营的理念,片面追求眼前利益,对桉树进行如机耕全垦整地、高密度种植、单一品种长期连续使用、不合理施肥、过度使用化学农药、全覆盖使用除草剂和超短轮伐期等不合理经营,带来了如生态脆弱、水源涵养功能降低等一系列生态问题。桉树人工林生态问题饱受社会争议,本文就经营中存在的问题展开论述,并提出科学经营桉树人工林的基本思路和策略,促进桉树人工林健康可持续发展。     

关于我国人工林长期生产力的保持

为了保持我国人工林的长期生产力和提高森林质量,达到可持续经营的目的。作者在以往研究工作的基础上,广泛收集了国内外有关成果与资料,概括论述了我国人工林森林生产力的现状、不能保持生产力的原因与机理以及长期保持人工林生产力的技术对策。按第八次清查的全国森林资源数据,每公顷蓄积量为89.79 m^3,其中天然林为104.6 m^3,人工林为52.76 m^3,人工林森林生产力明显低于天然林;我国优势树种人工林每公顷蓄积量也不高,如杉木为69.8 m^3,马尾松为56.2 m^3,落叶松为58.6 m^3,这些数据比日本2002年3月公布的人工林相似树种的数据低很多,如日本针叶树蓄积量为227.97 m^3·hm^-2,柳杉为295.83 m^3·hm^-2,落叶松为189.88 m^3·hm^-2。关于年生长量,按全国第七次资源清查的中龄林与近熟林的数据做统计:杉木人工林5.2~4.2 m^3·hm^-2,马尾松为3.2~1.8 m^3·hm^-2,柏木为3.4~3.2 m^3·hm^-2;但按作者掌握的我国重点或示范性、试验性小面积人工林生长量看,却很高,按我国编制的速生丰产林标准的生长量数据看比较高。我国大面积人工林生产力不高,短周期经营的杨树、桉树人工林也不高,主要原因是:(1)纯林化与针叶化严重。按第八次全国森林资源统计,纯林占人工林的85%,而且针叶化明显,人工乔木林10个优势树种中针叶林比例高达56.9%。人工纯林结构简单,生物多样性低,生物学上缺乏稳定性。人工纯林特别是针叶纯林,抗性低,抗自然灾害和大气污染能力均差,人工纯林维护地力的能力也弱。(2)集约育林的技术措施:立地控制技术未得到推广,适地适树适品种原则在育林中未能认真贯彻;密度、植被、地力控制技术也执行不力,大面积上的人工林仍属于粗放经营;连作引起林地土壤理、化、生物特性恶化,土壤质量衰退,导致林木生长不良,林分生产力逐代下降;造林作业造成水土流失,如杉木造林,传统的育林技术未得到明显改进,福建尤溪炼山后进行的3年观测结果表明,炼山和水土流失损失的有机质高达989.35 kg·hm^-2,养分586.26 kg·hm^-2。桉树在砖红壤进行的机耕整地,水土流失也很严重,不合理的造林作业,最终导致土壤质量与森林生产力下降。短周期培育人工林带来了2个重要问题,一是对林地肥力要求高,二是如何利用无性系才能保持长期生产力。短周期经营采用的无性系,生长速度快,生长量大,轮伐期短,养分需求量大,如刚果12号W5无性系,通常利用地上部分,以5~7 a的轮伐期计,消耗的养分达571.75 kg·hm^-2,我国培养短周期人工林的土壤质量本底原本普遍不高,如果采取连作,土壤有机质养分会明显下降,土壤质量衰退,并对其功能产生危害。我国杨树、桉树等人工林要达到短周期持续经营,还需要实行多无性系造林。我国人工林长期生产力保持的技术对策,应采取先进的集约育林措施,包括遗传控制、立地控制、密度控制、植被控制与地力控制。     

桉树的分布及生态评价与结论

本文介绍了目前桉树在世界上的分布情况（包括原生分布和引种分布）并用DMAP软件将桉树分布的国家进行标记。对桉树分布区的气候类型进行对比,发现气候类型与我国相近的国家桉树生长良好,林间物种丰富。通过对桉树生态问题的详细分析,表明只要经营科学合理,桉树人工林单位耗水耗肥量并不高,并且林内生物多样性较好,桉树人工林的生态环境问题不是其本身造成的,而是种植经营技术不科学导致。为提高桉树人工林的木材质量和生态效益,对桉树人工林需进行合理栽培,如重视科研、改良造林技术、集约经营和完善保障机制。     

我国桉树经营的技术问题与思考

桉树经营过程中出现的问题由来已久,这首先与我国社会经济发展水平较低有关,也与企业的经营理念不科学有关,和桉树本身的特性无关;虽然国内报纸、杂志、会议等多种形式对有关桉树经营问题的解释和分析,但对桉树的批评、误解、流言仍然较多,桉树的发展还处在风口浪尖。本文主要通过分析桉树在现实中所起的作用,尝试给桉树定位,以理清桉树的概念,解释桉树目前经营措施的来源;同时,通过分析桉树经营过程中存在的主要问题,特别是在林地清理和整地方面的问题,思考解决办法,协助人们正确认识桉树和桉树经营措施。     

Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations of Tasmania,Australia

The genus Mycosphaerella Johanson contains many pathogens capable of causing a severe impact on the growth of susceptible eucalypt species. The lack of knowledge about which species are present in Tasmania and their potential risk to the plantation industry prompted this study into the Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations in Tasmania. A total of 36 plantation and five road verge sites of E. globulus and E. nitens were sampled. Five Mycosphaerella species and three species from associated anamorph genera were isolated and identified in Tasmania; Mycosphaerella nubilosa, Mycosphaerella cryptica, Mycosphaerella tasmaniensis, Mycosphaerella grandis, Mycosphaerella vespa, Coniothyrium ovatum, Sonderhenia eucalypticola and Sonderhenia eucalyptorum. The most frequently isolated species with the highest incidence and severity of infection were M. cryptica and M. nubilosa. These two species appear to have the greatest potential to damage juvenile eucalypt plantations in Tasmania. A link between Mycosphaerella vespa and Coniothyrium ovatum is described for the first time.     

广西东门林场桉树无性系选育研究概述

对东门林场多年来所做的桉树无性系选育研究进展以及结果进行了总结分析。通过大量桉树树种(种源、家系)的引进,在优良种源、林分及优良单株选择的基础上,进行杂交育种和子代测定,开展优树选择和无性繁殖,开发出优良无性系,并通过无性系对比试验和区域试验,最终选育出优良无性系进行推广造林。东门林场先后选育出1800多个桉树优良无性系,其中已有140多个在林业生产中广泛推广和应用,树立了东门的“DH”(东门杂交种)品牌形象,充分展示东门林场的资源优势和技术优势,为我国的桉树无性系事业发展做出了贡献。     

正视桉树人工林生态问题

桉树给人类带来了不可估量的生态效益和经济效益。本文就桉树人工林的现状及生态问题展开详细论述,并就如何健康发展桉树产业提出合理的建议。     

科学发展桉树,为我国南方新农村建设作贡献

桉树具有生长快、轮伐期短、技术成熟、病虫害少和经济效益好等优点及良好的社会、经济和生态效益。合理的规划布局、推行可持续的经营技术并结合相应的社会经济措施可使桉树得到科学的发展,为南方新农村的建设作贡献。     

黄冕林场桉树人工林经营利用与经济效益分析

对广西黄冕林场3-5年生桉树人工林进行生长调查,探讨分析桉树经营利用经济效益。结果表明：桉树人工林中,不同林龄和同一林龄桉树人工林之间生长差异明显。不同的立地条件、初植林分密度对桉树人工林胸径、树高等生长影响很大。随着林分密度（标准地样木数）的增大,样木数与生长指标之间具有较强的负相关性。随着林龄的增大,这种林分密度负效应就越明显。从财务指标看,随着林龄的增大,总产值、纯利润和NPV均呈现增大的趋势,但IRR却并不如此,而是先增大后减少,在4a时,IRR达到最大值。从年份看,投资回收期为3a。结果表明桉树在广西黄冕林场这样的立地条件和气候条件下,表现适生、速生,且经济效益好,是营造短周期用材林的好树种。但为获得好的经济效益,必须注意树种、立地条件和栽培等措施的选择。     

Comparison of foliar nutrient concentrations between natural and artificial forests of Pinus sylvestris var. mongolica on sandy land, China

In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.     

Sustainable management of native and exotic plantations in Australia

The emphasis of plantation management changes as the resource and the market develop. This is especially the case when a plantation program is developing a new timber resource, is not the case with many of the Pinus radiata (D. Don) plantings in the southern hemisphere. Australia establishes and manages plantations of both exotic conifer and native hardwood (Eucalyptus spp.) plantations, and these vary in their stage of development. The tenure and objectives in establishment have varied, but some key aspects of the resources may be analyzed. Optimization of production per unit area was not a prime objective during the developmental stages of many exotic pine plantations. Currently, with increased commercial emphasis, this has changed to a greater focus on increased value through Site Specific Management and tree improvement through which gains of at least 20 percent are expected during the first stages. With a key objective of sustainability, questions regarding impacts of soils, water, and biological changes need consideration and are being addressed. The eucalypt plantation resource in Australia is smaller in extent than is the pine resource, but of increasing importance, especially as the plantations are perceived to be more environmentally and ecologically acceptable than exotic conifers. In the past, questions of productivity, especially in relation to impacts of natural pests and diseases, have been raised. Sustainability of all plantations is a critical aspect, however, for specific issues there are different emphases with different species. For example, the relatively, high removal of calcium in smooth barked Eucalyptus plantations is seen as important in long term forest management. This revised version was published online in June 2006 with corrections to the Cover Date.     

Realising the benefit of research in eucalypt plantation management

The development of a plantation eucalypt wood-based forest products industry in South Africa is outlined. Forest research that has contributed to increasing wood production from the ultimately finite land resource available for industrial plantations is reviewed. The application of this technology to eucalypt plantations by Sappi Forests is described and evidence for resultant increased wood production is presented. Improved silviculture, introduction of alternative species and deployment of genetically superior planting stock coupled to site classification and site-specific application of these technologies have all contributed to measured gains. The continued development and application of appropriate forest technology will be critical to a sustainable future for the industry in South Africa. Issues pertaining to this are discussed.     

开拓创新 科学经营 推进桉树可持续发展——浅析福建漳州发展桉树实践

通过对漳州发展桉树实践的调研,认为：在经营理念上,注意桉树与乡土树种实行嵌合式造林,短周期与长周期结合培育中大径材,速生桉树与珍贵桉树相结合发展,木材利用与生态利用相结合考虑;在营林措施上,推广近自然经营、营造复层混交林、保护乡土植被、改良林地生态环境;在宏观管理上,坚持科技先行、政策引领、产业带动。这些做法对桉树产区可持续发展具有借鉴意义。     

Lophodermium pinastri and an unknown species of Teratosphaeriaceae are associated with needle cast in a Pinus radiata selection trial

Spring needle cast (SNC) in Tasmania is defined by the early casting of pine needles and appears in 6‐ to 7‐year‐old pine plantations after canopy closure. The severity of SNC can vary significantly among trees growing within the same plantation. Fungal communities were surveyed in a Pinus radiata family trial, using DNA extraction from needles, PCR with fungal‐specific primers and sequencing to detect the presence of fungal species. Samples were taken at the same time as the trees were scored for disease severity. Trees with contrasting levels of SNC disease severity have significantly different needle fungal communities, but family pedigree and different ages of needle are not clearly distinguished by their fungal communities. All common fungal pathogens previously implicated in causing SNC were identified from the study, but of these, only Lophodermium pinastri was correlated with high levels of disease. Several species of Teratosphaeriaceae were detected, and one of these was also strongly associated with needle cast.     

Damage to foliage and stems caused by fungal pathogens in young eucalypt plantations in Zambia

Plantations consisting of non-native tree species were established on the Copperbelt of Zambia to supplement timber supply from natural forests and to meet the increasing demand of round wood and fuel wood for the copper mines. In early 2004, a disease characterised by severe leaf defoliation and death of juvenile trees suddenly occurred in plantations of the Copperbelt Forestry Company. This study was undertaken to determine the nature of the disease and extent of damage caused with a view of providing a framework for sustainable management of the plantations. Disease incidence, severity and impact on plantations using the crown damage index were assessed for three consecutive years. Eucalyptus grandis was more affected than E. cloeziana and leaf spot incidence and severity were higher in Kalibu, Kitwe District, than in Kafubu, Kalulushi District. The incidence in Kalibu was 90.4%, causing tree crown damage of 18.6% at the end of the assessment in 2006 compared to 17.5% incidence and 1.02% crown damage recorded in Kafubu. Fungi collected from leaf tissues included species of Aulographina, Cryptosporiopsis, Cylindrocladium and fungi in the Teratosphaeriaceae. Stem pathogens were identified as fungi in the Botryosphaeriaceae and Kirramyces sp. Diseases induced by these pathogens are increasingly becoming major threats to young eucalypts, resulting in poor stem form. Factors favouring disease development are described and these need to be properly managed to minimise the impact of diseases in addition to the need to establish selection and breeding programmes to develop tolerant genotypes to ensure a sustainable future for the forestry industry in Zambia.     

关于发展人工林与建立人工林业问题探讨

全世界森林面积为 34 5 4× 1 0 8hm2 ,其中 3%是人工林。人工林是重要的森林生态系统 ,在木材生产、环境保护和景观建设中具有重要功能和作用。人工林在生产功能方面的补偿作用 ,使天然林可以更好地发挥生态环境价值、森林娱乐和生物多样性保护功能。人工林可持续经营的前提是遗传材料的正确选择与营林实践艺术的结合以及保证这种结合的林业政策。愈来愈多地使用外来树种营建人工林是全球趋势。人工林对于环境和生物多样性的影响 ,可以通过合理的规划和经营措施得到解决。林木育种与遗传改良和经营制度的技术创新是不断提高人工林生态系统生产力的动力。人工林的可持续经营是一个十分复杂的问题 ,中国人工林实现可持续经营面临技术和体制两方面的挑战 ,但是 ,根本出路在于林业经济体制的改革 ,象农业那样 ,在市场经济环境中实行人工林产业化经营 ,建立人工林业 (Forestplantationindustry)。