广东郁南尾巨桉人工林密度效应

采用随机区组试验设计在广东省郁南县西江林场设置了4种株行距(1.7 m×4 m,2.0 m×4 m,2.5 m×4 m,3.0 m×4 m)试验,分析不同造林密度(1470、1250、1000、833株 ·hm-2)对0.8~7.8 a生尾巨桉(Eucalyptus urophylla×E.grandis)人工林保存率、树高、胸径、单株材积和林分蓄积量的影响.结果表明:不同造林密度对林分的保存率、树高、胸径、单株材积和蓄积量均有显著的影响;除0.8 a生的林分保存率外,其它年龄的林分保存率均随着造林密度的增加而降低,1470株 ·hm-2与其它3种密度间的林分保存率存在显著差异;造林密度对林分平均高有一定的影响,但差异较小;随着造林密度的增加,林分平均胸径和单株材积逐步递减,1470、1250株 ·hm-2与其它两种密度间的平均胸径和单株材积在2.8~7.8 a生时均存在显著差异;在7.8 a生时,以1250株 ·hm-2为造林密度的林分蓄积量最大,达195.0 m3·hm-2,分别比造林密度为1470、1000、833株 ·hm-2的林分高16.28%、5.86%和14.37%.以获得较高的林分蓄积量为目标,初步推荐1000~1250株 ·hm-2的造林密度.     

不同林龄尾巨桉林植被碳储量分配格局

基于对5个林龄尾巨桉林分不同层次植被生物量和碳含量的测定,本文研究了5个不同林龄尾巨桉林分植被碳储量的分配格局.结果表明:5个不同林龄尾巨桉林分中乔木层、林下灌木层、林下草本层和凋落物层碳含量均值分别为47.64%、50.59%、44.41%和48.92%,碳储量为7.17~145.15 t·hm-2,随林龄增加而增大.乔木层碳储量所占比例最大,随林龄增加乔木层碳储量所占比例也逐渐增大.     

施肥对尾巨桉生长及大径材材性的影响分析

对3种追肥处理1(N300P200K200)、处理2(N200P100K150)和处理3(N100P50K50),从12、27、42、50、62、75、88、99、110、144到192月生的尾巨桉生长量数据进行了统计分析,并在198月生时对每种施肥处理取7株样木进行了木材的基本密度、抗弯强度、弹性模量、硬度、干缩率以及皱缩率等指标开展研究,结果如下:追肥量与生长量成正相关关系.追肥量越多,生长量越大,这种差距从追肥后就开始产生,一直到192月生时都存在;但是,这种差距在大部分时间里都未达到显著水平:达到显著差距的只有施肥处理1和处理3之间,27月生时DBH达到0.01的显著性差异、平均高在12、27和37月生时达到0.05的显著性差异、蓄积量在27、37、42和50月生时达到0.05的显著性差异.材性指标上,大径材木材材性与追肥量的关系密切,增大施肥会影响木材材性,包括降低抗弯强度,增加弹性模量,降低端、径面和弦面硬度,降低基本密度,增加木材含水率等;达到显著差异的有:木材的抗弯强度、径面硬度被显著降低,达到了0.05的显著水平.木材边材基本密度降低更大,达到了0.01的极显著水平.经过多重比较的分析,都是常规施肥处理3与处理2和常规施肥处理3与处理1两两之间差异显著.处理1和2比处理3的抗弯强度平均分别降低了12％和14％、径面硬度分别降低了11.7％和14.1％,而边材基本密度分别降低了8.6％和8.1％;因此,在培育桉树大径材时,一定要考虑合理施肥量.     

尾巨桉中大径材立地指数编制及施肥对立地指数的影响

本文采用了连续12次16年生标准地的观测数据,以模型H=a+b/(c+A)作为导向曲线,标准年龄为7 a,编制了尾巨桉中大径材立地指数表.经过x2? 检验和标准差检验综合得出,所编制的立地指数合理,科学可行.本研究提出培育桉树中径材的立地指数不应小于20,培育桉树大径材的立地指数不应低于24.施肥提高了林地的立地指数,施肥量越多,立地指数提高的幅度越大;这种提高幅度在施肥量少的时候较大,当施肥量逐步增大的时候,立地指数的提高幅度逐渐变小.     

Allelopathic effects of essential oil from Eucalyptus grandis × E. urophylla on pathogenic fungi and pest insects

This study on the allelopathic effects and chemical components of the essential oi l from Eucalyptus grandis × E. urophylla shows that the leaf oil emulsion of E. grandis × E. urophylla can inhibit the proliferation of pathogenic fungi Fusarium oxysporum, Pyriculerie grisea, Glorosprium musa rum and Phytophthora capsici. Pupation and feeding of the pest insects Spodopteralitura Fabricius and Helicoverpa armigera Hubner are shown to be affected with restraining effects which increase with the increasing levels of oil concentration. A GC/MS analysis of the leaf oil indicated that the main components, with a relative content of ⩾3%, were alloocimene (43.22%), α-pinene (13.63%), γ-terpinene (5.49%), (E)-3,7-dimethyl-2,6-octadien-1-ol (3.58%), β-fenchyl alcohol (4.58%), and 2-amino-3,5-dicyano-6-(4-methoxyphenoxy)-pyridine (3.67%). Terpenes played an important role in the inhibitory effects of E. grandis × E. urophylla essential oil on pathogenic fungi and pest insects. Poor biodiversity of eucalyptus plantations is a function of allelopathy. __________ Translated from Chinese Journal of Ecology, 2007, 26(6): 835–839 [译自: 生态学杂志]     

施肥位点对尾巨桉幼林生物量分配及养分利用率的影响

以尾巨桉为研究对象,对其幼林进行培育,研究不同施肥位点对尾巨桉幼林生物量、养分分配及养分利用率的影响.结果表明:单位点穴施更促进根系生长,但是双位点穴施对树皮、叶片、树干、树枝和总生物量累积效果更好.养分分配除树根各处理磷素累积量差异不显著外,其他部位各养分累积量在各处理间均差异显著.不同处理叶片养分含量显著高于其他部位,且氮含量高于磷、钾含量.虽然处理Ⅱ各元素养分利用率及各部位养分累积利用率普遍优于处理Ⅰ,但差异均不显著.对尾巨桉施肥位点的研究处于初期阶段,还有待进一步探讨.     

Axial variations in anatomical properties and basic density of Eucalypt urograndis hybrid (Eucalyptus grandis 3 E. urophylla) clones

We studied two clones of Eucalypt urograndis hybrid (Eucalyptus grandis 9 E. urophylla), GR283 and GR330, grown in Tumkur district of Karnataka (India), and felled 5–6 years old three trees of each clo...     

巨尾桉人工林地径与胸径、树高相关模型的研究

根据巨尾桉人工林样木的地径D0、胸径D及树高H观测数据,采用多模型选优法和逐步回归法求解方程,经分析对比后分别建立了地径与胸径、地径与树高相关的2个数学模型:lnD=3.7275-18.6673/D0;H=32.0925-244.050 3/D0。应用这2个模型,配合一元材积表或二元材积表就可测定被伐木的材积。     

闽西尾巨桉造林及其生长效果分析

对闽西尾巨桉造林成效进行全面调查,分析了现有林分的生长特点,探讨了不同地理位置、海拔高度、立地质量等级以及施肥次数等因素对尾巨桉生长的影响,总结了尾巨桉造林失败的原因,并提出了闽西今后发展尾巨桉造林的看法。     

巨尾桉在龙岩市引种状况的调查分析

通过对龙岩市引种的巨尾桉 (E .grandis×E .urophylla)林分的生长状况及受冻情况的调查 ,结果表明 :巨尾桉生长迅速、丰产性好 ;冻害程度与地形、林分年龄、水体等因素有关。值得进一步扩大试验和在相应地区推广种植     

Genetic parameters and genotype by environment interaction of Eucalyptus grandis populations used in intraspecific hybrid production in South Africa

In South Africa, Eucalyptus grandis is an important species due to its fast growth and general suitability of its timber for a range of products. However, E. grandis is susceptible to fungal diseases such as Crysoporthe austroafricana and Coniothyrium sp. cankers in the subtropical region of Zululand and is therefore mainly planted as a parental species in a hybrid combination with E. urophylla in this region. The current strategy is to maintain large breeding populations of both parental species in order to provide improved elite selections for hybrid crosses. In order to develop the best interspecific hybrid breeding strategy for E. grandis, it is important to first determine estimates of genetic parameters of the pure species parents. Estimating the genotype by environment interaction (G×E) is also necessary in proposing the basis for setting up breeding populations and selecting environmentally stable genotypes. With this in mind, two E. grandis full-sib progeny trials were planted in Zululand and one in the KwaZulu-Natal Midlands region. The aims of this study were firstly to determine the magnitude of G×E of E. grandis across the three sites; secondly, to estimate the genetic parameters for growth of the E. grandis parents selected for intraspecific crosses; and lastly, to identify the best parents to use for intra- and interspecific crosses in future hybrid breeding programmes. Results of our study indicated that G×E would be practically negligible for growth in Zululand and one group of elite parents can be used for hybrid crosses in this region. In general, growth traits were under low to moderate genetic control, and the variation in additive genetics enabled us to identify E. grandis parents that could be utilised for intraspecific crosses and deliver progeny with genetic gains of 28.4%. Our study also highlighted that a relatively large portion of the genetic variation was explained by dominance genetic variation and a strategy to capture this non-additive variation needs investigation. Although our study achieved the stated aims, it must be kept in mind that E. grandis is mainly used as a hybrid parent with E. urophylla in Zululand. A study to investigate whether the parents with good general combining ability values from our study are also good general combiners in interspecific hybrid combinations with E. urophylla needs to be conducted.     

Early growth and survival of Eucalyptus pellita provenances in a range of tropical environments,compared with E. grandis,E. urophylla and Acacia mangium

Provenance/family trials of Eucalyptus pellita F. Muell were established at three seasonally-dry tropical sites in northern Australia (two in north Queensland and one on Melville Island in the Northern Territory), and at Luasong, a tropical site with year-round high rainfall and humidity in Sabah, Malaysia. After 2–3 years, it was clear that New Guinea provenances outperformed Queensland provenances in their survival, growth and form, and in their crown health, in the humid tropical environment of Luasong. New Guinea provenances were also clearly superior to Queensland provenances in their growth and form at Melville Island, but less clearly so at Cardwell, Queensland. Among Queensland provenances, Helenvale and Kuranda were superior to the more northerly Cape York provenances, Tozers Gap and Lankelly Creek, while there was little difference between the two New Guinea provenances tested, Bupul-Muting (Irian Jaya) and Keru (Papua New Guinea). Significant differences in growth traits, form and survival were demonstrated between families within provenances. In a species/provenance trial at Luasong, E. pellita displayed better growth and survival than tropical provenances of E. grandis and E. urophylla, but was inferior in growth and crown health to Acacia mangium.