适宜干旱造林的桉树

耐干旱的桉树桉树共有600种以上,几乎全部产于澳大利亚和塔斯马尼亚,此外,这个属的树种在爪哇、帝汶岛、新几内亚、新不列颠和新爱尔兰也出现:桉树在澳大利亚约占森林面积的95%。桉树在原产地生长在各种不同的气候和土壤条件下,从干热沙漠至寒冷山坡     

海南西部桉树人工林生长特征及其对气候环境的响应

在海南西部儋州林场选取空间相邻、自然条件相似、不同林龄序列的桉树人工林作为研究样地,通过定点系统监测,分析不同林龄桉树人工林生长变化特征及其对气候环境的响应。结果表明:1)桉树人工林胸径4—7月增长较快,7—10月增长最快,其它月份明显减缓。2)1—3a桉树人工林平均单株材积和单位面积材积年内增加幅度逐渐增加,3a达到最大值,4a较大,5a增长明显减缓。3)林龄显著地影响单株桉树生长,其中3a影响最大;土壤水分、降水极显著影响桉树生长,而气温对单株生长量影响不显著。4)土壤水分随林龄增加而减少,较低土壤水分对桉树人工林生长产生干旱胁迫作用,致使桉树单株材积增加减少,尤其是5a桉树人工林材积增加量减少最为明显。     

从化桉树、南洋楹速生丰产林的生长表现调查

本文通过对广州市北部山区从化市2年半生的桉树、南洋楹速生丰产林的生长表现进行调查,结果表明：在两个标准样地间,桉树、南洋楹的平均胸径以及南洋楹的平均分枝数无显著差异,而平均树高差异显著,说明桉树、南洋楹的胸径生长以及南洋楹的分枝数受遗传控制的程度较高,而树高生长受环境条件影响较大;桉树与南洋楹在平均胸径与平均树高两个性状上均达到极显著差异,并且这两个性状的变异系数,桉树均比南洋楹小,说明桉树的胸径生长和树高生长均比南洋楹稳定,受环境条件的影响较小,所能适应的立地条件和环境条件较南洋楹广泛。     

东喜马拉雅地区高山栎类 (Quercus Sec.suber)种群变异和环境异质性研究(英文)

该文研究分布在我国东喜马拉雅地区 (云南和西藏 )及四川的高山栎类种群间的形态变异和遗传距离 .在自然条件下 ,这些栎类的生长形态随纬度的增加和降水的减少从高大的乔木变成矮小的灌木 .该地区多样的气候和复杂的地形条件为高山栎类提供了各种形态、生长和遗传变异的可能性 .种群内和种群间的遗传距离随生境条件、山地地形和主风方向的变化明显 ,但与水平距离关系不大 .西藏地区以地势险峻和气候多变为特色 ,云南地区以高山峡谷为特色 ,二地区高山栎的种群遗传距离分别为 0 396和 0 36 5,前者显著高于后者 (P <5% ) ,但却都高于四川地区的高山栎种群遗传距离 ,并达到极显著水平 (P <1% ) .环境的异质性越高 ,高山栎类的变异越大 ,种群变异和物种进化与气候、生境、地形地貌和土壤等环境的异质性密切相关 .尽管东喜马拉雅地区是以大陆性季风为主气候特征 ,但高山栎类的叶片、直径和根系对环境异质性的适应变异与分布在地中海地区的、冬雨夏旱气候条件下的冬青栎类 (Q .ilex)十分相似 .不同地区的环境异质性必然导致物种进化和种群变异的差异 ,然而 ,高山栎类种群在两个截然不同气候区内的高度相似性恰恰说明了它们可能来自于一个共同的祖先或从同一个地区演化而来 ,所以它们才有相同的适应策略     

干旱胁迫对沙棘克隆生长的影响

总结水分条件对沙棘生长、克隆繁殖能力、病虫害以及生理生化的影响:水分充足情况下,植株成活率高、个体较大、克隆繁殖能力强、子株生长倾向于"聚集型"、抗病虫害能力强;干旱胁迫环境使种群将更多的物质和能量分配于适应或抵抗干旱胁迫,表现出个体变小、克隆繁殖潜力受到抑制、子株生长倾向于"游击型"、病虫害加剧、光合速率低,导致种群寿命缩短、更新不良、早衰概率升高。但目前的研究仅限于生理或生态层次,缺乏克隆生长与干旱胁迫的因果关系探讨。建议今后加强基因表达、生理生态、内源激素、克隆行为对干旱胁迫响应规律及其因果关系方面的研究,从不同层次系统地揭示干早胁迫机制及适宜的水资源有效性范围,用以指导造林地选择、造林设计、生态恢复工作。     

桉树的变异和良种选择

我们在长期引种桉树的实践工作中,发现桉树在长期适应新的环境条件的过程中,其生态特性会产生许多变异;同时,桉树又是一个异花授粉的树种,在自然生长情况下,种间杂交非常容易发生从而产生许多变种、交型,不仅型态干差万别,而且生长优劣也十分悬殊。在良种繁育过程中,我们可从利用桉树变异这个特点,提     

不同桉树在昆明市海口林场的早期生长研究

对昆明市海口林场2012年栽植的5种桉树早期生长性状进行了观测研究。结果发现，5种桉树中，造林成活率较高的有本沁桉、邓恩桉及多利桉，树高和地径表现最优的是多利按。不同种桉树中苗圃地生长表现最优的，上山栽植以后生长表现不一定最优，这与不同生长发育阶段、不同环境条件有着密切关系。     

施肥对桉树根系延伸的促进作用研究

桉树作为我国主要的人工用材林,为我国各方面行业提供了大量树木资源。而提升桉树成长水平,增加桉树经济效益,是当前桉树培育方面的主要问题。通过对不同施肥情况对桉树根系延伸的促进作用及不同施肥量对桉树生长影响进行了研究,结果表明：不同肥料种类对桉树根系生长有着不同的影响,磷肥主要影响桉树幼苗的垂直延伸,桉树专用肥主要影响桉树根系的水平延伸和扎根能力,氮肥主要影响桉树根系的根尖数量。而肥料施用量对桉树的生长情况有明显的促进作用。经过1年的生长数据对比,胸径增长了2.3 cm,树高增高5.4 m,平均胸径和树高均高于同一时期使用其他肥料种植的桉树。在实际培育过程中,可以分阶段、分环境给予桉树不同的肥料配比,以达到最优的生长效果,同时合理增加施肥量,促进桉树生长,提升桉树经济效益。     

闽西桉树栽培适应性分析

通过对闽西桉树引种栽培适应性分析,结果表明：不同地理位置、海拔高度、立地质量对桉树生长存在显著差异,相同或相似条件下,不同的桉树品种(品系)生长量不同,所表现的耐寒性亦有差异。     

沙米生长特性调查

通过对沙米生长特性、种群动态及其对水分的影响等方面系统的调查,探讨流动沙丘上若留有片状枯萎的沙米,（翌年）沙米植株之间就不再生长新生沙米的可能原因。同时,利用先锋植物的这种生态适应机制,探讨了沙漠地区短命植物适应干旱环境的生长特性。     

Infestation Density of Eucalyptus Gall Wasp,Leptocybe invasa Fisher and La Salle (Hymenoptera: Eulophidae) on Five Commercially Grown Eucalyptus Species in Tanzania

This study explores infestation density of Leptocybe invasa on five commercially grown Eucalyptus species in Coastal, Plateaux, and Southern Highlands agroecological zones of Tanzania. Infestation density between agroecological zones, Eucalyptus species, age classes and tree crown parts, relationship between stand altitudes and the magnitude of infestation, damage index, species age, and abundance of L. invasa on different Eucalyptus species were examined. There were significant differences in infestation between zones and Eucalyptus species. Eucalyptus tereticornis was more affected, followed by E. camaldulensis, and E. saligna was the least while E. grandis and E. citriodora were not affected. No significant differences in damage between different crown parts were observed. Trees with age of 1–3 yr were damaged more than those of age 4–6 yr. Pest infestation increased with an increase of L. invasa abundance but decreased with an increase of altitudes. Control efforts needs to focus on controlling the spread of the pest, using silvicultural methods and planting resistant Eucalyptus species.     

Assessment of morphological and genetic diversity in <Emphasis Type="Italic">Gmelina arborea</Emphasis> Roxb.

Gmelina arborea is an important timber-yielding tree that grows naturally in the tropical and subtropical regions of Southeast Asia and has also been introduced as a plantation species outside these regions. Genetic diversity in this tree species was observed in stone/seed-related traits and in vitro responses of cultured nodal segments from plants of eight different populations representing natural forests, fragmented forests and plantations. Variance analysis showed significant differences between populations for these traits. However, it was not possible to separate the different populations using these traits by multivariate analysis, even after environmental variation was reduced over six subcultures. Genetic diversity was therefore analysed using molecular markers. Inter-simple sequence repeat (ISSR) primers yielded 95% polymorphic loci among the eight populations and UPGMA analysis enabled separation of these populations on the basis of their genetic distances. Diversity was also analyzed using population genetics parameters like Nei’s genetic diversity and gene differentiation. Nei’s genetic diversity was 0.29 between populations and 0.11 within populations. AMOVA analysis indicated 41 and 59% within- and between-population genetic diversity, respectively. Mantel test suggested that genetic differentiation between six Indian populations was positively correlated to geographic distance (r = 0.626, P = 0.029). Assessment of the genetic variation in G. arborea populations is an important step in selection of conservation strategies for this species since diversity forms the basis for species adaptation.     

金沙江干热河谷造林树种游离脯氨酸含量与抗旱性关系

金沙江干热河谷地区的主要造林树种中,以马占相思、山毛豆、真珠相思、大叶相思、台湾相思、绢毛相思、坡柳在旱季游离脯氨酸累积较多;赤桉、泰国赤桉、柠檬桉、尾叶桉、大叶桉、新银合欢、苏门答腊金合欢、滇刺枣无明显差异。无论从种属间或种源地,还是不同生态类型,都看不出游离脯氨酸的累积与抗旱性之间有明显的相关关系。作者认为,用游离脯氨酸作为植物抗旱性指标有一定局部性,但用它作为某些树种在干旱胁迫时植物体发生的     

金沙江干热河谷区8个造林树种的生态适应性变化

对金沙江干热河谷区8个造林树种的有关生理生态特性进行了研究。结果表明:相思类树种在旱季水分自然饱和亏缺较大,乡土树种坡柳和3种桉树则是雨季水分亏缺较大,具有WSD高而RWC低的植物同样具有很强的抗旱能力;比叶面积增大是植物提高抗旱能力的一个表现方面,但增加干物质积累、提高细胞质浓度也是途径之一;干热逆境可造成叶绿素含量降低,雨季叶绿素含量有较大提高,叶绿素a/b值也随之得到提高;参试树种的糖分含量旱季比雨季高,除马占相思外,其它树种淀粉与糖的比率则旱季比雨季低;在干热逆境胁迫下,7个树种(除尾叶桉)的游离脯氨酸含量有不同程度增加,旱季植株易出现萎蔫现象,有部分或较多叶片脱落的树种积累的游离脯氨酸较多。除造林效果较差的马占相思与其它7个树种有较多差异外,造林效果较好的7个树种在生理生态变化方面有较多相似性;同时,同类树种间有明显的一致性;乡土树种坡柳则在某些方面更近似于相思类树种,在某些方面又近似于桉树类树种;除马占相思外,3个相思类、3个桉树类树种与乡土树种坡柳同样在金沙江干热河谷区表现出较强的生态适应性。     

Effects of soil drought on seedling growth and water metabolism of three common shrubs in Loess Plateau, Northwest China

The growth and water metabolism of three common shrubs on the Loess Plateau were studied under soil with different water contents. Results showed that water consumption of those species decreased with the increase in drought stress, and water consumptions of these shrubs were different: Forsythia suspensa was the greatest, and Syringa oblata was the lowest. The growth rate of new branches and leaf area of three species were the fastest under adequate soil water conditions, and were the lowest under severe drought. Under the same water conditions, the growth of F. suspensa was the fastest while that of S. oblata was the slowest. The water content, proline and chlorophyll content of different species changed with the increase in soil water stress. The leaf water content of Periploca sepium and F. suspensa was obviously higher than that of S. oblata, while the leaf proline content of F. suspensa and S. oblata was lower than that of P. sepium. The ratio leaf chlorophyll a: b of F. suspensa and S. oblata decreased with the decrease in soil water content. Although these three shrubs had different mechanisms in response to drought stress, they all had higher drought resistance and could adapt to the drought condition on the Loess Plateau. This paper provided some bases for choosing tree species on the Loess Plateau. __________ Translated from Acta Botanica Boreali-Occidentalia Sinica, 2007, 27(1): 91–97 [译自: 西北植物学报]     

Components of the water balance for tree species under evaluation for agroforestry to control salinity in the wheatbelt of Western Australia

The soil water balance technique was used to study evaporation from two fodder tree species, tenEucalyptus species and annual pasture over a three year period after planting in the Western Australian wheatbelt. Evaporation is the total water loss by the processes of transpiration, evaporation from the soil surface and evaporation of water intercepted by plant canopies.Evaporation from both fodder trees and from seven of theEucalyptus species was greater than from pasture for one or more of the study years. The maximum difference in evaporation between trees and pasture was 82, 84 and 70 mm in the first, second and third study years, respectively. Higher evaporation from trees was associated with greater depletions in soil water than occurred beneath pasture. Upward movement of water from wet soil beneath the root zone was found under trees, with a maximum flux of 30 mm observed over a one year period beneathE. camaldulensis.The water use efficiency of fodder trees was significantly higher than for mostEucalyptus species, due to greater yields from fodder trees. Biomass production was found to be a good indicator of the water use of eucalypts over the first two years of growth, but the relationship between productivity and water use was found to differ for species with tree and mallee forms. In the third year of study, obvious differences in the relation between water use and yield were observed for some species of eucalypts with high evaporation.     

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.     

Water availability preceding long-term drought defines the tolerance of <Emphasis Type="Italic">Eucalyptus</Emphasis> to water restriction

Plantations of Eucalyptus species are expanding across South America into regions where drought conditions can reduce growth rate and result in substantial commercial loss. Understanding the mechanisms of drought tolerance in Eucalyptus is essential for the successful production in drought-regions. The main objectives of this study were to evaluate how water availability preceding a long-term drought period affects morphological, physiological and molecular traits of four Eucalyptus clones grown under field conditions. The study areas are located in north-eastern Brazil with an average rainfall of 800 and 1500 mm per year. At each rainfall regime, the following clones were evaluated: 1404 (Eucalyptus urophylla), 1407 (E. urophylla × E. camaldulensis), 1296 and 6500 (E. grandis × E. urophylla). Our results indicate that trees growing in the area with higher annual precipitation were more stressed after long-term drought, compared to those stands previously exposed to mild water-restriction period. The genetic materials showed distinct responses to drought, which allowed their separation in two groups: drought-tolerant (1404 and 1407) and drought sensitive (6500 and 1296). The former group shows some important adaptations to drought, such as decreased leaf area (avoiding excessive transpiration rates), higher antioxidant activity and carotenoid concentration (leading to lower lipid peroxidation). In conclusion, previous exposure to water deficit may provide the benefit of increased defense protection during future water deficit. From all measured variables, the leaf area, antioxidant compounds and changes in ¹³C and ¹⁸O isotope abundance reflect some of the most important morphological and physiological alterations in order to mitigate the water stress damage in drought-tolerant genotypes.     

Productivity,soil fertility and soil erosion under cassava based agroforestry systems

The interactions between component species in three-tier agroforestry systems were studied on sloping laterite soils of South India for three years. The wood yield of Eucalyptus was found to increase in association with the intercrops, with cassava + groundnut resulting in the best growth of Eucalyptus. Green forage yield of Leucaena was adversely affected by cassava but was improved by inclusion of a short duration seasonal crop. Both spread and mean length of lateral roots of Eucalyptus and Leucaena were restricted by cassava intercropping. Both the tree species were found to reduce the tuber yield of cassava and also the pod yield of both the seasonal crops when grown in association. Monocropping with cassava was found to improve the fertility and an increase in phosphorus and potassium contents of the soil was observed when grown in association with Eucalyptus and Leucaena. Soil fertility fell considerably after three years of cultivation of the tree species. The nutrient uptake by cassava was low when grown in association with perennial species. Both run off and soil loss were effectively reduced when cassava was grown in staggered mounds under Eucalyptus and Leucaena.     

Photosynthetic physio-response of Taxodium ascendens seedlings to different soil water gradients

Four different kinds of water treatments were applied to study the photosynthetic eco-physiological characteristics of Taxodium ascendens seedlings in the environment of the Three Gorges hydro-fluctuation belt. The four kinds of water treatments were: normal growth water condition (CK), light drought stress (T1), soil water saturation (T2), and soil submersion (T3). The results showed that different water treatments could effectively influence the content of the photosynthetic pigment, leaf gas exchange and apparent resources use efficiency of T. ascendens seedlings. It was also demonstrated that the T. ascendens seedlings could not only tolerate water submersion and wet conditions but also endure a certain degree of drought. To establish a protection forest system in the hydro-fluctuation belt in the Three Gorges Reservoir Area, the species T. ascendens is suitable for planting in conditions of root submersion or water-saturated soil. In case it is planted in drought conditions, this tree species should be watered appropriately in order to keep its normal net photosynthetic rate. Translated from Forest Research, 2006, 19(1): 54–60 [译自: 林业科学研究]