我国岷江柏林分类及群落特征

Community classification and structure of Cupressus chenegiana forest

关键词:  岷江柏林  干旱河谷  NMDS  植被恢复  TWINSPAN

Key words:  Cupressus chenegiana forest  dry valley  NMDS  restoration  TWINSPAN

摘要:

调查了位于马尔康县、金川县、小金县、丹巴县和理县的37个岷江柏样地中的乔木、灌木和草本层的信息。利用TWINSPAN将37个样地划分为8个群丛，NMDS的结果与之相似；在群落结构方面，岷江柏乔木层郁闭度约55.68%，3 m以上植株密度1 518 ind/hm2，高度分布和直径分布均呈倒“J”型分布，位于金川的群落乔木层还分化为2个亚层；灌木层的情况受环境和林冠层的影响较大，各地区间也有较大差异，平均盖度约40%，丰富度约21.82 sp/plot；草本层平均盖度约40%，丰富度约27.91 sp/plot，地区间差异不大，以中旱生种类为主，灌草间在盖度上呈现显著负相关，而在丰富度上呈现极显著正相关关系。根据乔木层的情况可将岷江柏林划分为纯林和针阔混交林两个不同亚群系，其乔木层结构、林下植物盖度、丰富度和物种组成均有较大差异。这两个亚群系处于不同的演替阶段，后者可能是由于破坏而形成的。混交林可能是退化或恢复过程中的关键群落类型，如果停止破坏并加以保护仍可恢复为岷江柏纯林。

Abstract:

Cupressus chenegiana，an endangered species endemic to China，mainly appears in the ecotone between dry valley and montane forest，which was the key area of restoration. Most publications had concentrated on the resistibility of C.chenegiana under drought stress，but types of C.chenegiana forest and its community structure were still little known to us. To provide a scientific base for ecosystem restoration and further study，we investigated 37 plots which located in Barkam County，Jinchuan County，Xiaojin County，Danba County and Li County. Information of tree，shrub and herb were collected，such as diameter and height of individual trees，coverage of tree，shrub and herb layer，richness of shrub and herb. The data matrix which composed of 333 species(shrub and herb) from 37 plots was subjected to TWINSPAN and NMDS. We found that：(1)Form.C.chenegiana was divided into 8 associations by using TWINSPAN，and two subformations(pure forest of C.chenegiana and mixed forest) featured with canopy layer composition were recognized；(2)coverage of canopy layer was 55.68%，density of tree(H≥3 m)was 1518 ind/hm2，the structure of height and diameter showed a inversed“J”shape distribution，and the forest in Jinchuan County featured with multiple storey(2 sub canopy layers)；(3)coverage of shrub and herb layer were both 40%，and the richness of shrub and herb layer were 21.82 sp/plot and 27.91 sp/plot respectively. Due to the evidence from tree and shrub layers’composition and structure，we speculate that the two subformations are on different successional stages. Mixed forest is the key vegetation type in restoration. With appropriate conservation，the mixed forest will succede into pure forest.