黄土丘陵子午岭油松天然林群落特征研究

对黄土丘陵区子午岭天然油松林的群落特征进行了研究。结果表明，油松群落共容纳种子植物67种，分属23科54属，区系组成丰富；属的分布类型以温带性质为主，共65个，占总属数的66.7％；在群落外貌特征上，油松群落以地面芽植物为主，占75.9％；叶级以中型叶为主，共96种，占57.85％；群落可分为乔、灌、草3个层次，并有层间植物伴生；随年龄增长，群落中油松种群空间结构呈集群分布→随机分布→集群分布变化；种群格局强度随年龄阶段变化缓慢，处于较弱的生境异质性变化状态中。

Community characteristics of natural Pinus tabulaeformis forest in Hilly Loess Regions

The community characteristics of natural Pinus tabulaeformis forest distributed in Hilly Loess Regions were investigated.the results showed that were 67 seed plants belonging to 23 families,54 generas.belonged to temperate biome,As regards to the physiognomy of the community Hemicryptophyta made up 75.9% of the total,dominating the community.In the community,96 species with middle-sized leaves made up 57.8%,and there were 139 single leaf species accounted for 83.7% of the total,There was a complicated vertical structure in the community,which could be divided into three layers:Arbor layer,shrub layer and herb layer.In addition,there were also a lot of inter-stratum plants in the community.It is also found that the lack of seedlings,saplings and small trees was due to both the self-thinning caused by intra-specific competition and the alien-thinning by inter-specific competition for the light resource in the stand.The dynamics of the community showed that the community was stable and in a process of development.