摘要
近海区域受持续性风力胁迫,防护林树种木麻黄在生长过程中树冠结构产生较大变化.为揭示木麻黄树冠结构对环境条件变化的可塑性响应特征,在福建省长乐市大鹤国有防护林场距海岸线450-500 m(样带1)、750-800 m(样带2)、1 050-1 100 m(样带3)设置3个距离梯度的样带,运用Strahler法研究木麻黄的分枝格局,并采用分形理论测定冠形的分形维数.结果表明:(1)在不同距海处木麻黄的分枝格局差异较大,距离海岸线越远,木麻黄各级枝条的分枝长度、总体分枝率、枝径比和逐步分枝率不断增大,但各级枝分枝角度表现出随机性分布的特征.(2)样带1树冠迎风面与背风面相比,分枝长度、枝径比2:1和枝径比3:2、分枝率均显著小于背风面,随着距海岸线距离的增加,差异性不断减弱.(3)在海风作用下,树木表现出对主干偏移式形态响应,即距海岸线越近,主干偏移角越大.(4)木麻黄距海岸线越近,其树冠的分形维数越小,占据空间能力小,反之则占据空间能力大.因此,在沿海区域,木麻黄会通过冠形调整、减小分枝长度等方式以适应风力胁迫.
Due to continuous wind stress in coastal areas, Casuarina equisetifolia L., one of the species of coastwise protective shelterbelt, shows variety in crown architecture during its growth. To determine the adaptive morphological plasticity of crown architecture to different environmental conditions, we set up three belt transects at 450-500 （transect 1）, 750-800 （transect 2） and 1 050-1 100 m （transect 3） from the coastline in C. equisetifolia protection forest in Dahe State-owned Forest Farm, Changle County, Fujian Province of China. In each belt transect, two 10 m× 50 m samples were used to survey the basic indices such as DBH, height, under branch height, crown breadth, deviation angle of stem, etc., and fractal dimensions of crown breadth were calculated. Furthermore, based on Strahler method, 7 trees were selected in each transect to survey the branch length, branch diameter and branch angle to horizon. The findings were as follows： （1） the bifurcation ratio, branch length and ratio of branch diameter of C. equisetifolia became greater with the increase of coastal distances except random branch angle to horizon. （2） the branch length, ratio of branch diameter and bifurcation ratio on the windward in transect l were significantly smaller than those on the leeward side. However, the trend weakened gradually with the increase of coastal distances. （3） With morphological response to wind, the stems of trees showed the highest deviation angle in transect 1, followed by transect 2 and 3. （4） Having higher capacity to occupy the space, fractal dimension of crown breath in transect 3 is higher than the others. Our research showed that C. equisetifolia has adaptive responds to wind stress through crown adjustment, branching length decrease, etc. Fig 3, Tab 4, Ref38
出处
《应用与环境生物学报》
CAS
CSCD
北大核心
2013年第4期587-592,共6页
Chinese Journal of Applied and Environmental Biology
基金
教育部博士点学科专项基金(20090315120008)
国家自然科学基金项目(31100303)资助~~
关键词
分枝格局
距离梯度
木麻黄
树冠形态
分形维数
branching pattern
distance gradient
Casuarina equisetifolia L.
crown morphology
fractal dimension
