排序方式： 共有80条查询结果，搜索用时 15 毫秒
1.
Edival Ângelo Valverde Zauza Lúcio Mauro da Silva Guimarães Nilza de Lima Pereira Sales Samuel Alves dos Santos Rafael Ferreira Alfenas Acelino Couto Alfenas 《Forest Pathology》2023,53(2):e12806
An outbreak of a new and severe disease was observed in Eucalyptus plantations of Bahia state, Brazil. An Ascomycota fungus has been frequently associated with the main symptoms of the disease namely leaf spot, branch cankers, shoot blight, defoliation, and dieback. Based on morphological characteristics, phylogenetic analysis (ITS and TEF-1α genes), and pathogenicity test on Eucalyptus plants, Pseudoplagiostoma eucalypti was identified as the causal agent of the disease. Although P. eucalytpi has been known from in Brazil since 1998, this is the first report of it causing severe disease and die-back on Eucalyptus spp. and we also record new symptoms associated with the pathogen. 相似文献
2.
One hundred and fifty-four jarrah (Eucalyptus marginata) and 85 marri (Corymbia calophylla) trees were measured and assessed, and the numbers and sizes of hollows in these trees were determined by destructive sampling; 665 hollows were located and measured. The relationship between tree diameter and tree age was determined from counts of annual growth rings on 162 of these trees. Large trees and trees with moderately senescent crowns individually bear the most hollows. Although the number of hollows found in individual trees increased with tree diameter, the distribution of tree diameters in the forest is skewed and the large number of small trees with diameters between 40 and 80 cm contribute approximately 50% of all hollows in the jarrah forest. The distributions of entry size, and of hollow depth, are highly skewed, with small hollows occurring more frequently than large hollows. Although jarrah trees bear more hollows than marri trees and the distribution of entry sizes is similar for both tree species, the hollows in jarrah are significantly smaller than the hollows in marri. Most hollows are cylindrical in shape, vertically oriented and occur in dead wood in the tree crown. Relatively few hollows (14%) occur in the tree bole or at crown break. Counts of hollows made from ground level are inaccurate as estimates of the actual number of hollows in trees. 相似文献
3.
4.
Greenhouse trials with containerized Eucalyptus globulus and E. urophylla seedlings were made to determine effective inoculum spore densities (Scleroderma cepa from temperate Australia, and S. citrinum from sub-tropical China) and spore storage conditions (fresh spores or spores stored for 5 years at room temperature or at
4 °C; S. albidum, S. areolatum and S. cepa from Western Australia). Inoculation with 106 or 108 spores/seedling increased eucalypt growth by up to 46% in height and 42% in dry weight compared to non-inoculated seedlings
at 12 weeks after inoculation. Mycorrhizal formation was poor at 102 spores/seeding. Spores stored at 4 °C for 5 years were as effective in forming mycorrhizas as freshly collected spores when
a standard density of 106 spores/seedling was applied. It is recommended that spore densities ≥104 be used for inoculation of containerised eucalypts and that spores be stored at 4 °C until use. 相似文献
5.
桉木抽出物中多酚化合物的特性研究 总被引：10，自引：0，他引：10
采用化学分析和光谱分析相结合的方法，从制浆造纸的角度，重点对雷林一号桉木的多酚化合物的特性进行了研究。结果表明：幼龄材的抽出物含量较少，适宜于制浆的采伐期为５～７年。１５年生雷林一号桉木心材中的多酚类化合物以水解单宁为主（占原料的５．９８％），其次为缩合单宁（１．９１％）。稀碱预处理桉木，可除去大部分多酚类化合物。存放过久的桉木中多酚化合物大部分变成‘黄粉’，既不溶于水也不溶于丙酮，只溶于稀碱或亚硫酸钠。桉木制浆前采用碱预处理可减轻多酚化合物对制浆产生的不良影响。 相似文献
6.
Ciro Abbud Righi Vincent S. J. A. Couderc Carlos Rodrigues Pereira Hilton Thadeu Zarate do Couto Luciana Duque Silva 《Journal of Sustainable Forestry》2013,32(1):75-87
ABSTRACTEucalyptus is widely cultivated in homogeneous monocultures throughout the world alongside plants of the same age. Furthermore, the productivity of forest stands is highly dependent on how solar radiation is intercepted and used. Meanwhile, it is possible to consider cultivating trees of different ages in the same area, and thus under different regimes of available solar radiation, creating a sequence of plantings and harvestings and to develop Eucalyptus-based agroforestry systems. We have examined biomass accumulation of Eucalyptus camaldulensis along a shade gradient. Eucalyptus trees presented power-law responses to increasing irradiance for biomass, indicating it has low plasticity and is unable to maintain growth under lower irradiance levels. Biomass partitioning showed no dependence on available irradiation. Leaf density presented very little increase toward sunnier places meaning that an increment in Eucalyptus biomass would be mostly due to its increase in size and thus higher radiation interception. Careful management of shade will be a key consideration for the integration of Eucalyptus into agroforestry. With knowledge of the growth habits of different species, we will have the potential to propose more perennial ways in which to manage land and reduce anthropogenic disturbances by avoiding clear-cuts of areas that removes all plant structures. 相似文献
7.
广东高要南部低丘桉树人工林下植被物种多样性分析 总被引：1，自引：0，他引：1
对广东高要南部低丘桉树（Eucalyptus spp．）人工林林下植被物种进行了调查分析。结果表明,林下植被物种最少有156种以上,分属56科和103属,乔木21种,灌木59种,藤本20种,草本36种,总体Shannon-Wiener指数为2．26。种群数目大于5％的优势种均为草本植物,其中芒箕（Dicranopteris dichotoma）占绝对优势（46．2％）,这是林下植被物种丰富度较高而多样性偏低的主要原因。林下植被物种组成、丰富度和多样性在不同地域之间均有显著的差异,但在林分龄级之间则没有明显的变化。 相似文献
8.
桉树林萌芽枝处理一直是林分改造及碳汇林建设需要解决的重要问题,如何通过药物处理及人工处理达到理想的效果,更是桉树林萌芽枝处理研究的关键所在.文章以增城区“退桉”为背景,开展了尾叶桉(Eucalypt urophylla)人工林伐桩及其萌芽枝8种不同抑萌处理方法比较.结果表明,盖灌能+套袋处理和2.4-D丁酯乳油+套袋处理尾叶桉伐桩枝叶枯萎率最高,为100％;伐桩腐烂比例最高为盖灌能+套袋处理,为83.6％,2.4-D丁酯乳油+套袋处理为49.2％;施药处理12个月,萌芽枝复萌比例最低的是盖灌能+套袋处理,为14.3％;各处理成本最高是盖灌能+套袋处理,为2 302.5元/hm2.使用盖灌能+套袋和2.4-D丁脂乳油+套袋处理尾叶桉伐桩及萌芽枝抑萌效果最好. 相似文献
9.
The loss, fragmentation and degradation of native vegetation are major causes of loss of biodiversity globally. Extinction debt is the term used to describe the ongoing loss of species from fragmented landscapes long after the original loss and fragmentation of habitat. However, losses may also result from habitat changes that are unrelated to fragmentation, which reduce breeding success and recruitment. Many woodland birds have declined in fragmented landscapes in Australia, probably due to loss of small, isolated populations, though the ecological processes are poorly understood. We record the progressive regional loss of two ground-foraging, woodland birds, the Brown Treecreeper Climacteris picumnus and Hooded Robin Melanodryas cucullata, in northern New South Wales, over 30 years. This has happened despite most habitat loss occurring over 100 years ago, suggesting the payment of an extinction debt. Our observations suggest that several ecological processes, caused by habitat loss, fragmentation or degradation, and operating over different time scales, have led to both species’ declines. Female Brown Treecreepers disperse poorly among vegetation remnants, leaving only males in isolated populations, which then go extinct. In contrast, Hooded Robins suffer high nest predation in fragmented landscapes, producing too few recruits to replace adult mortality. Foraging by both species may also be affected by regrowth of ground vegetation and shrubs. We found little support for a major role played by drought, climate change or aggressive Noisy Miners Manorina melanocephala. We propose that both extinction debt in the classical sense and ongoing habitat change frequently contribute to species’ decline in modified landscapes. Management to arrest and reverse such declines needs to consider these multiple causes of decline. For instance, reconnecting isolated populations may be inadequate alone, and activities such as appropriate grazing, fires and the addition of woody debris may also be required. 相似文献
10.