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111.
杉木炭疽病发生的预测模型 总被引:1,自引:0,他引:1
本文应用数量化理论I原理建立杉木炭疽病发生的预测模型,结果表明,杉木炭疽病发病率同海拔、坡向、坡位、土层厚度、林龄和质地有大或较大的相关;杉木炭疽病感染指数同坡向、坡位、海拔、质地、紧密度和土层厚度有大或较大的相关。 相似文献
112.
This study focuses on the problem of irregular diameter structure in a silver fir–beech selection (plenter) forest with a “surplus” of large diameter trees and a lack of natural regeneration and small diameter trees. We sampled 274 plots (900 m2 each) in the Belevine research site (266.24 ha) in the mountain region Gorski Kotar (Croatia), where diameter (dbh) distribution, diameter increment, and natural regeneration were analyzed in detail. A low density of natural regeneration, weak annual recruitment of small (10 cm dbh) diameter trees (only five trees per hectare), delayed diameter growth of trees, and a low annual rate of trees reaching the next dbh class were attributed to the current irregular dbh structure. The stand development prediction for the next 50 years is based on a simulation model, which considers the current diameter structure, increment, recruitment, and future cutting regime. Intensive cutting in the first of five 10-year cutting cycles (intensity higher of 25%) is needed to initiate natural regeneration and to accelerate growth of young silver fir trees. In the next 50 years, the irregular diameter structure will be gradually improved. 相似文献
113.
以湖南省会同县的杉木为例,研究了直径生长率与树高生长率、材积生长率的相关关系。采用生长量修正法建立了杉木单木竞争生长量模型,回归拟合出树高生长指数κ的相关模型作为中介模型,推手出了杉木直径生长率、树高生长率、材积生长率的预估模型。 相似文献
114.
基于大岗山林区相似立地条件前后3次生物量调查研究资料,结合杉木人工林固定样地长期观测材料对杉木人工林生物量的变化规律作了较为详尽的研究,得到了如下主要研究结果:(1)对于同一林分,除叶生物量和某些枝生物量存在一个减小的时期外(5a至8a时),单株和林分各组分生物量均随林龄的增加而增大。在12a前的林分速生期间,叶、枝、干所占比重微弱增加,致使地上部分比重增加,而根比重减小;在干材期(12~16a),单株各组分所占比例趋于稳定。(2)立地指数对单株和林分各组分的生物量、总生物量以及生物量分配比率均存在显著影响,且这种影响随着林龄的变化而变化,并受初植密度的制约。(3)随着初植密度的增大,单株各组分生物量明显减小,干生物量分配比率在任一林龄时刻均呈下降趋势;由密度所形成的不同林分生物量间的差距随林龄呈减弱的趋势。 相似文献
115.
曲靖市营造生物防火林带研究与应用 总被引:1,自引:0,他引:1
按照不同海拔区域,不同立地条件,选择生长迅速、郁闭快、适应性强、萌发率强、枝叶茂密、含水量高、耐火性强、含油脂少、不易燃烧的耐火树种,草种进行立体配置营造林带,并对不同配置的林带进行阻火抗火试验。筛选出最佳的防火树种和草种,按最佳配置营造防火林带,在云南省曲靖市推广应用。 相似文献
116.
Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands
Changes in soil chemical and microbiological parameters in small (185 m2) and medium (410 m2) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high
soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected
a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend
of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites
and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested
that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in
small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested
a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate
(FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to
changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil
temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest
that the creation of small gaps represents the silvicultural practice with minor environmental impact. 相似文献
117.
1991 ̄1995年试验结果表明,在江西分宜花岗岩残积物发育的黄红壤上,杉木幼林施N、P、K及配合处理,使树高、胸径、蓄积总生长量指标分别达到5.67 ̄6.59m、8.35 ̄9.28cm、67.922 ̄96.41m^3/hm^2,较对照增长5.6% ̄20.2%、7.4% ̄17.5%、21.6% ̄56.2%。在各种施肥处理中,以50kg/hm^2P2O5的效果最佳,其连年生长量效应显著持续到第5年; 相似文献
118.
XU Ming REN Haiqing LUO Xiuqin YIN Yafang Research Institute of Wood Industry Chinese Academy of Forestry Beijing P. R. China 《中国林业科技(英文版)》2006,5(4):27-32
INTRODUCTION Chinese fir (Cunninghamia lanceolata) is a very important timber species in the southern China (Shi Jisen et al. 1987). It is good, fast-growing, and exempts from serious plant diseases. Its plantation is big in terms of size in the South of China and its storage stock is very rich, which is about 20% of the national commodity wood (Zhou Shuangquan et al. 2000). And the lumber becomes mainly commercial construction materials in China because of straight grain, light and so… 相似文献
119.
采用正交试验方法 ,对过磷酸钙、菜籽饼粉及复合肥不同的施肥水平影响杉木种子出苗情况进行了效果对比试验。结果表明 :混合施用过磷酸钙与复合肥的处理组合均能促进杉木种子出苗 ,最佳组合为每hm2 混合施用 75 0kg过磷酸钙及 375kg复合肥 ,出苗率比对照高出 30 3%。 相似文献
120.