桉树人工林木材生长应变研究

以我国南方生长较好的4种人工林桉树为研究对象，测试并比较了4种桉树立木的纵向生长应变及其相关性,结果表明：不同桉树种间生长应变差异显著；相同树龄的尾园桉的生长应变与胸径成直线相关。以上结果可为桉树实体木材的加工利用提供借鉴。     

Carbon return and dynamics of litterfall in natural forest and monoculture plantation of Castanopsis kawakamii in subtropical China

The amount of carbon returned through litterfall and its seasonal pattern were studied in a natural forest of Castanopsis kawakamii (NF) and adjacent monoculture plantations of C. kawakamii (CK) and Chinese fir (Cunninghamia lanceolata) (CF) in Sanming, Fujian Province, China. Mean annual carbon return through total litterfall over 3 years (from 1999 to 2001) was 5.097 t·hm⁻² in the NF, 4.337 t·hm⁻² in the CK and 2.502 t·hm⁻² in the CF respectively. Of the total carbon return in the three forests, leaf contribution accounted for 58.96%, 68.53% and 56.12% and twig 24.41%, 22.34% and 26.18%, respectively. The seasonal patterns of carbon return from total litterfall and leaf-litter were quite similar among the three forests. A peak of carbon input from litterfall in the NF and the CK occurred in spring except for the highest annual C return through branch litter of the NF in summer, while the CF showed the maximum C return in summer. The results of this study demonstrate that the natural forest has a greater C return through litterfall than monoculture plantations, which is beneficial to the increase of soil organic matter storage and the maintenance of soil fertility. [Supported by the Teaching and Research Award Program of MOE P.R.C. (TRAPOYT) and the Key Basic Research Project of Fujian Province (2000F004)]     

不同立地条件香椿人工林木材材质的比较

通过对不同立地条件下香椿人工林木材物理力学性质的测定和比较分析表明:香椿人工林木材密度和干缩性随着立地级的提高而减小;木材顺纹抗压强度、抗弯强度和硬度:Ⅰ级地<Ⅱ级地<Ⅲ级地,抗弯弹性模量、抗劈力、冲击韧性:Ⅱ级地>Ⅰ级地>Ⅲ级地,顺纹抗剪强度:Ⅱ级地>Ⅲ级地>Ⅰ级地。差异显著性t检验表明:香椿人工林木材密度Ⅰ级地、Ⅱ级地、Ⅲ级地间差异不显著。香椿人工林木材干缩性和力学性质指标Ⅰ级、Ⅱ级、Ⅲ级地3者间有的指标差异极显著,有的指标差异显著,大部分指标差异不显著。     

沙地樟子松天然更新与降水因子的灰色关联度分析

沙地樟子松人工固沙林的天然更新在大部分引种地不能很好地进行，其天然更新存在着某些障碍因子。通过对辽宁省昌图县傅家林场樟子松天然更新情况的调查，采用灰色关联度分析的方法，对更新与降水因子的关系进行了分析。结果表明，更新产生的当年12月和翌年1，2月的降水量，即冬季降雪情况与天然更新关联最大。说明了冬季降雪是影响樟子松天然更新的一个关键因子。     

火炬松人工林养分体内转移与内循环研究

对江苏省下蜀林场火炬松人工林 (15年生 )地上部分养分体内转移和内循环特点进行了初步研究 ,结果表明 :(1)在体内养分转移中 ,叶的贡献最大 ,N、P、K和Mg元素的平均转移量均大于枝和干 ;地上部分养分N、P、K和Mg元素的转移率分别为 44 9% ,34 5 % ,2 0 8%和 30 7%。 (2 )地上部分养分归还量N、P、K、Ca和Mg元素分别 5 5 787,6 13,2 6 70 ,70 79和 2 0 30kg·hm- 2 ·a- 1 分别占需要量的 36 6 7% ,44 6 5 % 5 5 3% ,78 0 2 %和 42 84% ;地上实际消耗土壤中的养分量N、P、K、Ca和Mg分别为 2 2 48,2 13,4 6 4,2 6 98和 7 41kg·hm- 2 ·a- 1 ,分别占吸收量的 2 3 99% ,2 2 76 % ,11 84% ,2 4 32 %和 2 1 0 9%。 (3)与当地的杉木林和次生栎林相比 ,该火炬松人工林养分利用率高 ,并处于养分消耗阶段。     

杉木和I-72杨人工林木材干缩性质的研究

通过对杉木和I-72杨人工林木材南北向、不同高度位置、不同径向位置横向干缩(弦、径向)的测量,研究上述3个因素对2种木材横向干缩(弦、径向)的影响规律。结果表明:南北向的不同对杉木和I-72杨人工林木材的干缩均无显著影响;高度位置的不同对杉木和I-72杨木的弦向干缩均有显著影响,而对径向干缩则无显著影响;径向位置的不同对杉木和I-72杨人工林木材的径、弦向干缩均有极显著影响:从树皮到髓心,木材径、弦向干缩逐渐减小,与其基本密度的变化趋势一致。     

Leaf-water potential and soil-water depletion of walnut mulched with polyethylene and intercropped with alfalfa in Central Italy

In Italy, new agroforestry cultural models could play an important role in the diffusion of plantation forestry timber species. We studied the stem growth rates and leaf water potentials () of common walnut (Juglans regia L.), and gravimetric soil moisture (_DW) depletion during the third and fourth growing seasons in an agroforestry trial in central Italy. Since the establishment of experimental plots in 1992, walnut was intercropped with alfalfa (Medicago sativa L.), with or without polyethylene (PE) mulching along tree rows. By the end of the study period, the unmulched-intercropped walnut was almost 68% smaller in stem diameter and height than the sole-unmulched control, demonstrating walnuts sensitivity to alfalfa competition. The competitive effect of alfalfa on walnut stem growth was effectively controlled/reduced by PE mulching. Stem growth rates of mulched-intercropped walnut were always lower than the control, but much higher (ca. 235% in stem diameter and height) than those of unmulched-intercropped walnut. The higher field performance of mulched-intercropped walnut compared to the un- mulched-intercropped treatment was associated with higher soil moisture and predawn and midday values during the summers driest periods. The presence of PE mulching was also associated with lower levels of soil moisture during the early and late growing season, but this did not negatively affect walnut and growth rates. These results suggest that in the climatic conditions of central Italy, competition for soil moisture between young common walnut trees and alfalfa can be substantially lowered, but not completely eliminated, by PE mulching.This revised version was published online in November 2005 with corrections to the Cover Date.     

不同类型长白落叶松人工林各龄期的木材产量评估

根据立地指数的不同将长白落叶松林地分为7个立地等级(立地Ⅰ~Ⅶ),结合其营林技术规程选择造林密度为2 500株/hm2、3 300株/hm2和4 400株/hm2等不同类型的长白落叶松人工林分作为评估对象。在前人研究的基础上计算该不同类型林分在各林龄阶段的平均树高,利用相关模型推算相应林龄阶段的林分平均胸径和林分平均单株材积。建立长白落叶松人工林分的密度定量管理模型,根据此模型确定不同立地等级不同初植密度长白落叶松人工林分在理想状态下的间伐时间、间伐强度和木材收获量,为其营林生产和科研提供参考。     

田间供水与杨树生长关系的研究——Ⅰ.供水处理对杨树生长、树体结构和叶量的影响

在集约栽培的杨树人工林中作了小区灌溉试验,进行了林木生长指标、水分生理指标与供水量关系的研究。结果表明,供水大大促进了林木生长,其树高、胸径和材积的年增长量均随供水量的提高而增加。1983—1986年其树高、胸径、材积分别比对照增加 17.2—24.6％、10.7—22.1％和22.0—42.6％。供水还影响到树体的结构,有利于同化产物向枝条中运输与积累,促进了树干、枝条、叶数与叶面积的增长。     

NUTRIENT CYCLING IN THE DAHURIAN LARCH PLANTATION ECOSYSTEM

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