排序方式： 共有4条查询结果，搜索用时 109 毫秒
1
1.
本文通过对9条分布均匀、相对较窄的不同疏透度(透光疏透度,下同)(0.13～0.33)的树木林带和不同疏透度(0.00～0.80)风障组合的野外风速观测,确定了树木林带和风障的最适疏透度分别为0.25和0.13。基于林带结构(疏透度)与风速降低的关系,确定了林带主带间距离的主要参数,即,林带结构系数(δ)和以主害风为代表的小气候参数(Lrp)。另外,通过对林带树木的野外调查,应用树木解析技术确定林带成林高(H0)。因此,树木林带的主带间距可以通过林带结构系数、希望降低风速的比例和树木生长模型来确定。本文以杨树林带为例,具体确定了杨树林带的主带间距。该研究结果不仅适于树木林带的设计,同时适于其它生物材料或人工风障的设计。图4表5参40。 相似文献
2.
农田防护林主要间距离的确定——基于林带结构与风速降低的关系 总被引：3，自引：0，他引：3
Relative windspeed reduction was measured behind nine relatively narrow, homogenous tree windbreaks with porosities between
0.13–0.33, and behind 28 combinations of model stubble barriers representing 25 different optical porosities (0.00–0.80).
The optimum porosities observed were 0.25 and 0.13 for tree windbreaks and stubble barriers respectively. Based on the relationship
between windbreak structure (optical porosity) and wind reduction, the chief indices for determining spacing interval, i.e.,
the windbreak structure index (δ) and the parameter of microclimate, represented by the problem wind (L
rp
), were determined. Additionally, investigations on shelterbelt trees were carried out, and stem-analysis techniques were
used, to develop a method for determining the mature height of tree windbreaks (H
0). Optimal spacing intervals between windbreaks could be predicted from the indices of a given windbreak structure, percentage
of reduction of windspeed desired and tree growth model. A hypothetical example for determining the spacing interval of principal
poplar windbreaks is given at the end of this paper. The results can be applied not only to tree windbreak design but also
to other plant materials and artificial barriers for wind protection.
Foundation item: This study was supported by Innovation Research Project of Chinese Academy of Sciences
Biography: ZHU Jiao-jun (1965-), male, Ph. Doctor, PhD advisor. Professor of Institute of Applied Ecology, the Chinese Academy of Sciences,
China, Scholar researcher of Faculty of Agriculture, Niigata University, Japan.
Responsible editor: Song Funan 相似文献
3.
松崎健:用简易照像机进行地上拍照的数值解析研究(1)(《日本林学会志》1978年第60期、第281—289页)是为了解析用普通照像机所拍摄的地面照片,即便在相当恶劣的条件下,也可能导出的数值解析法。这个方法的演算原理是:把从两张照片上取得的情报做为两个独立座标系的方向向量,然后,分析各对向量的共面性,决定各个坐标 相似文献
4.
海岸林风害危险率评价的理论推导 总被引：2，自引：0，他引：2
本文在对间伐和风害之间关系的讨论和以往有关研究结果的基础上,确定了一种林木风害危险率的估计方法,用于评价间伐对林木风害的影响。这种对单株黑松及整个黑松林分的风害危险率估计,是根据风速廓线、枝条分布和透光分层疏透度(OSP)系数推导出来的。结果表明:如果枝条分布模型中的参数β等于单株树冠中风速廓线模型的衰减系数αs,参数H/D1.33可用于比较和评价对单株树木的风害危险率。这一原理也同样适用于整个林分,即用林分内风速廓线衰减系数α和透光分层疏透度(OSP)的分布中的衰减系数ν,结合D1.33估计和比较林分风害危险率。文中对间伐与非间伐单株黑松风害危险率进行了估计,得出了间伐两年后可以降低单株黑松风害危险率的结论;同时给出了确定林分风害危险率估计的过程图。图3参45。 相似文献
1