都江堰地区小型哺乳动物群落与生境类型关系的初步研究

Preliminary studies on the relationships between communities of smallmammals and habitat types in Dujiangyan Region，Sichuan

于 2000年 10月底至 11月初，对都江堰地区中亚热带常绿阔叶林带不同生境类型中小型哺乳动物群落的多样性变化进行了初步研究。共捕获小型哺乳动物12种，其中啮齿目（Rodentia）鼠科（Muridae）10种，食虫目（Insec－tivora）■■科（Soricidae）2种。总捕获率为10．67％。在所调查的7个生境中，以干扰较轻的次生林中小型哺乳动物物种多样性指数（1．8438）和均匀度（0．9475）最高，灌丛、次生林1、原生林和弃耕地均有较高的多样性指数；农田受人类的干扰最严重，物种单一，优势度（0．5703）明显；柳杉林中的多样性指数（1．3380）和均匀度（0．8313）均较低。但原生林的物种多样性指数（1．4305）略低于次生林（1．8475和 1、4610）、灌丛（1．6398）和弃耕地（1．6566）。根据不同生境内群落相似性指数进行系统聚类，7个生境在相似性指数0．0952处全部聚合在一起。灌丛、原生林和次生林中主要分布有森林型小型哺乳动物，聚为一类，为森林群落型；柳杉林和农田以大足鼠（Rattus nitidus）为优势种，聚为一类，为农田群落型；弃耕地一方面由于群落多样性指数较高（1．6566），另一方面其农田型小型哺乳动物仍占较高比例（46.67％），所以在聚类图中另成一类，为农林交错型。结果表明。

Variation in diversity of communities of small mammals in seven different habitats from the me-dian subtropical evergreen broad-leaved forest belt in the Dujiangyan Region was studied from the end ofOctober to the beginning of November 2000. Twelve species, comprising ten Muridae (Rodentia) andtwo Soricidae (Insectivora), were captured. The total rate of small mammals captured was 10. 7%. Ana-lyses of diversity of small mammals in different habitats show that species diversity index (1. 84) andevenness index (0. 95 ) are highest in secondary forest, where human disturbance has been moderate inrecent years. Those in shrubland, secondary foresVprimary forest and abandoned farmland are also high,while species are rare and the species dominance index is high (0. 57 ) in farmland, where human dis-turbance is most serious. Species diversity index (1. 34 ) and evenness index (0. 83 ) are also lower inplantation of Cryptomeria fortunei. Species diversity index in primary forest (1. 43 ) is slightly lower thanthat in secondary forests (1. 85 and 1. 46), shrubland (1. 64 ) or abandoned farmland (1. 66 ), whichresults from habitat degradation. Based on similatity indices, seven habitats can be clustered at the levelof 0. 095 with systematic clustering. Small mammals of forest type are mainly distributed in shrubland,secondary forests and primary forest, which are clustered into one group. Farmland and plantation of C.fortunei are dominated by Rattus nitidus and belong to the farmland type. Abandoned farmland is an eco-tone of farmland and forest, because of its higher diversity index (1. 66) and higher rate of small mam-mals of farmland type (46. 7% ). The results show that diversity is the lowest in habitats where disturb-ances are most serious (e. g. farmland and plantation of C. fortunei) and highest in moderately disturbedhabitats (e. g. secondary forest, shrub and abandoned farmlands) and slightly lower in disturbed hahitats(e. g. primary forest).