tree stratum

Diameter distribution of tree stratum reveals truncated normal distribution.

乔木层株数随胸径分布呈现截尾正态分布。

that the species structure is complicated. the communities have four layers-tree stratum, shrub layer, lianas and herb layer.

总体上物种多样性高，种类组成复杂，群落乔木层、灌木层、草本层和层间植物层次明显。

Oriental Oak was absolutely dominant in the tree stratum, its importance value was the highest, it was the dominant and preponderant species in the community, main concomitant species were Oriental White Oak, Tabularformed Pine and Japanese Mulberry.

乔木层以栓皮栎占绝对优势，其重要值最高，是群落的建群种和优势种，主要伴生树种有槲栎、油松、鸡桑；

The abundance of species was shown to be similar in the tree stratum and the shrub stratum and conspicuously lower than that in the herb stratum.

结果表明，乔、灌木层物种丰富度相近，且明显低于草本层。

Then, the relationship between between species diversities and growth form in 20 plant plots was studied, the conclusion is that species richness of herb stratum is higher than tree stratum and shrub stratum obviously, tree stratum is lowest;

对20个乔木样地的植物生长型与物种多样性关系分析表明：草木层的物种丰富度指数明显高于灌木层和乔木层，乔木层最低；