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951.
952.
Acacia mangium is a very fast growing species belonging to the family Leguminosae that has been introduced in the plantations in Bangladesh for its faster growth and wide range of adaptability. The present study aimed at development of growth and yield prediction models for the species using simultaneous equation method. Models were selected for the species to estimate stand dominant height, stand diameter, stand basal area per hectare and total volume yield per hectare. Paired t-test, 45-degree line test, percent absolute deviation and biological principle of stand development were used for the validation of chosen models. The results suggest that the models derived were statistically and biologically acceptable and could be satisfactorily used for stands of Acacia mangium of ages 4–7 yrs based on a base age of 6 yr. 相似文献
953.
黄土丘陵区主要人工林水保及其土壤水分生态效益研究 总被引:1,自引:0,他引:1
通过研究表明,不同类型植被减少径流和泥沙的功效不同,东坡不同类型植被小区径流深由大到小的顺序为:荒坡>沙棘(平茬)>沙棘+小叶杨>农地;北坡为:油松>油松+沙棘>沙棘林;东坡产沙量由大到小的顺序为:农地>荒坡>沙棘(平茬)>沙棘+小叶杨,北坡为:油松>油松+沙棘>沙棘。不同类型植被在生长季的土壤水分平均值均很低,其中对土壤水分利用强度由大到小分别为柠条>沙棘>刺槐,100cm以下土层,不同类型林地土壤均存在利用性干层。 相似文献
954.
Dongsheng?Li Shaohui?Fan Aijun?Hecsf@forestry.ac.cn" title="aijun@mail.ecc.u-tokyo.ac.jp csf@forestry.ac.cn" itemprop="email" data-track="click" data-track-action="Email author" data-track-label="">Email author Faquan?Yin 《Journal of Forest Research》2004,9(4):307-312
Covering a vast territory, China is rich in forest resources and diversified environments. The changes in forest resources
have a direct bearing on environmental quality. This paper gives a detailed account of the dynamic change in forest resources
in China, including the overall process of forest evolution, the status quo, and features of the existing forest resources
and the development and use of major forest resources. In addition, it analyses the current situation of China’s environment
and explores the main contributing factors based on the overall environmental situation. To achieve sustainable management
of forest resources and improve the environment in China, the Chinese Government attaches great importance to the protection
and development of forest resources as well as to environmental development and improvement. The paper gives an overview of
current thinking for sustainable forest resource and environmental development in the future and highlights the current focus
of efforts toward this objective. 相似文献
955.
A dendrochronological technique was used to investigate canopy recruitment of beech (Fagus engleriana Seem.) trees in western Hubei Province of Central China by identifying growth releases through gap formation. The results
indicated that 83% and 17% of the canopy trees regenerate in gaps and the understory, respectively. Radial growth analyses
demonstrated that there are three modes for beech regeneration and canopy recruitment: (1) gap origin without suppression;
(2) gap origin with period(s) of suppression; and (3) understory origin. Multiple periods of release and suppression imply
that beech regeneration and canopy recruitment are very sensitive to gap formation. 相似文献
956.
957.
Dahurian larch (Larix gmelinii Rupr.) Rupr is one of the dominant species in both natural and man-made forests in northeast China. Effects of site factors,
including topography, soil properties and nutrient elements (P, Ca, K, Mg, Mn, Zn, Cu, Ag, Co and Ni) on the growth of larch
were analyzed in detail, qualitatively and quantitatively. The ordination technique was used to group the site factors and
to classify sites for larch. Analysis indicated that height growth, diameter (DBH) and volume of the larch varied among site
types and this will be of theoretical and practical significance in developing larch plantations. 相似文献
958.
中国历史时期的森林文化及其发展 总被引:9,自引:0,他引:9
但新球 《中南林业调查规划》2003,22(1):62-64
详述了森林文化的概念及内涵,系统总结了森林文化在不同历史时期的特征及相应历史背景。 相似文献
959.
960.
本文在9年生人工纯林中,采用固定标准地、固定标准株连续3年对树高、胸径实测的方法,计算并比较阌 害与末受害木材积及单位面积材积的 失。 相似文献