扁刺栲-华木荷群系次生林林下物种多样性分析

对四川中亚热带扁刺栲(Castanopsis platyacantha)—华木荷(Schima sinensis)群系人工杉木林、水杉林、日本落叶松林和天然次生林林下植物进行了群落调查和物种多样性分析。结果表明：(1)杉木林、水杉林、日本落叶松林和次生扁刺栲—华木荷林(20a)的物种丰富度分别为62，59，53和32；Simpson多样性指数分别为7．95，7．08，9．24和5．38；Shannon—Wiener多样性指数分别为3．67，3．3l，3．64和2．46。(2)人工林林下植物群落之间的群落系数和相似度系数分别为0．45～0．60和0．62～0．82；人工林林下植物群落与次生阔叶林林下植物群落之间的群落系数和相似度系数分别为0．19～0．53和0．55～0．77。(3)人工林林下物种多样性比次生林高的主要原因可能是风倒木和站干死木导致人工林乔木层郁闭度减小，增加了林下的光照，从而改蛮了林下的微生境。表6参19。

PLANT SPECIES DIVERSITY OF UNDERSTORY COMMUNITIES IN CASTANOPSIS PLATYACANTHA-SCHIMA SINENSIS FORMATION

The survey on understory community was conducted in order to study the species diversity, community coefficient and community similarity coefficient of 4 types of secondary forests in Castanopsis platyacantha-Schima sinensis formation area of Sichuan Province. The results indicated that: (1) The species abundance was 62, 59, 53 and 32, the Simpson diversity index was 7.95, 7.08, 9.24 and 5.38 and the Shannon-Wiener index was 3.67, 3.31, 3.64 and 2.46 in Cunninghamia lanceolata, Metasequoia glyptostroboides, Larix kaempferi and secondary broad-leaved forests, respectively. (2) The community coefficient and community similarity coefficient of plantations range from 0.45 to 0.60 and from 0.62 to 0.82, respectively. While the community coefficient and community similarity coefficient varies from 0.19 to 0.53 and from 0.55 to 0.77 between plantation and secondary broad-leaved forest, respectively. Furthermore, the fallen trees and standing dead woods caused by wind or snow reduced the stand density, and increased understory light level, which changed the understory micro-habitat, and was probably the key factor to result in higher understory species diversity in plantations. Tab 6, Ref 19