杉木人工林林下植物物种多样性的动态特征

研究不同生长发育阶段杉木林林下植物演替过程的动态特征，结果表明：偶然种伴生阶段（幼龄林阶段），林下植物种类组成和数量第一次繁荣，结构比较简单；林下植物贫乏阶段（郁闭阶段），种类和数量较少，结构简单；林下植物相对稳定阶段（近成熟林和成熟林阶段），种类组成和数量不断增加，群落呈现稳定的杉木层、灌木层和草本层的三层结构；入侵性演替阶段（老龄林阶段），种类组成和数量再度繁盛，一些阔叶树种生长进和乔木层，形成具有多物种和多层次的群落结构。不同生长发育阶段的杉木林林下植物α多样性存在明显差异和波动性。幼林阶段林下植物总体和灌木层的丰富度指数、多样性指数和均匀度指数均较高；林分郁闭阶段各指数有明显下降；随后又有所增加，至老龄杉木林阶段达到量大值；在3a、9a和31a杉木林中，物种多样性垂直结构表现出灌木层＞草本层＞藤本植物的格局；在20a杉木林中，物种多样性垂直结构则表现出草本层＞灌木层＞藤本植物的格局；在56a老龄林中，物种多样性垂直结构表现出灌木层＞乔木层＞藤本植物＞草本层的格局。表3参6

DYNAMICAL CHA RACTERISTICS OF UNDERGROWTH PLANT DIVERSITY IN CHINESE FIR PLANTATIONS

The dynamic characterristics of succession process of undergrow th plants in different aged Chinese fir plantations were studied.The results sho wed that in accompanying stage of accidental species,undergrowth plant species a nd quantities flourished first,and the structure was very simple. In sparse stag e of undergrowth plants, species and quantities were few,and structure was simpl e. In relatively stable stage of undergrowth plants,species and quantities incre ased, and Chinese fir community formed stable 3-layer structure including Chinese fir layer,shrub layer and herb layer. In invading succession stage of un dergrowth plants, species composition and quantities flourshed again,some broad -l eaved tree species started to grow into tree layer,and the multi-species and mu lti-layer community structure was formed. The α diversity indexes of under growth plants were obviously different and fluctuated. The richness index, diver sity index and evenness index of total undergrowth plants of shrub layer were hi gher in young Chinese fir plantation. In the stage of closed forest stand, all i ndexes obviously decreased, then increased again, reaching maximal value in o ld-growth plantation. Vertical structure of species diversity showe d shrub layer>herb layer>liana plant in 3,9 and 31 year-old plantations, in 20 year-old plantation, herb layer>shrub layer>liana plant, and in old-growth Chi nese fir plantation, shrub layer>tree layer>liana plant>herb layer. Tab 3, Ref 6