黄土高原森林林隙特征及植物多样性

Study on the Features and Plant Diversity of the Forest Gaps on the Loess Plateau

通过对马栏林区林隙的调查研究,发现其林隙大小以20-40 m2和40-60 m2居多,其中40-60 m2所占数量比例和面积比例均最大。林隙的年龄结构是中前期和中后期数量较多,分别占到林隙总数的42.31%和38.46%。林隙形成方式以砍伐树桩占的比重最大,说明该地区现有的林隙大多是人为干扰形成的。林隙形成木中辽东栎（Quercus liaotungensis）和油松（Pinus tabulaeformis）的株数相对较多,且主要是由中小径级的树木构成。不同大小林隙的植物多样性变化表现为：乔木层面积为40-60 m2时其多样性较高,灌木层和草本层面积均为20-40m2时其生物多样性较高。在不同发育阶段中,草本层的多样性指数在林隙发育的中前期最高,而乔木层和灌木层均在林隙发育到中后期时最高。

After investigating the forest gaps on the Loess Plateau, it is found that the sizes of the forest gaps vary mainly in ranges of 20 - 40 m^2 and 40 - 60 m^2, in which the proportions of number and size of the forest gaps of 40 60 m^2 are the highest. The quantities of age structure of the forest gaps are high in the prometaphase and latemetaphase, and their proportions are 42.31% and 38.46% of the total forest gap number respectively. The propor- tion of deforested stubs is the highest in forming the forest gaps, which reveals that the forest gaps are mainly caused by human disturbance in this area. The numbers of Quercus liaotungensis and Pinus tabulaeformis are more in forming the forest gaps, and these trees have mainly the middle and small diameters. The species diversity of forest gaps in arbor layer is high when the gap area varies in a range of 40 - 60 m^2, while it is high when the gap area in shrub layer and herb layer varies in a range of 20 - 40 m^2. At different development stages of forest gaps, the species diversity in herb layer of forest gaps is high when the gap is in prometaphase, while it is high in arbor layer and shrub layer when the forest gaps are in late-metaphase.