关键词: 延安人工林区, 小型兽类, 季节动态, 生境, 优势度

Abstract: In order to provide scientific bases for the prevention and control of pest small mammals , the seasonal fluctuations of the small mammals community were studied in the Yan'an plantation region. This research will help to find out the distribution and structure characteristics of small mammals community in the Yan'an plantation region. The investigation was carried out from April to October in 2001. According to the traits of natural conditions , the plantation region can be divided into three kind of basic habitat , i.e. Chinese pine plantation area , locust plantation area (both are typical of this plantation area ) and weeds and shrubs area. Method of trap-day was adopted in the investigation of small mammals above ground while method all captured in plot was adopted in that of small mammals underground in each habitats , the collection of small mammals sample and the statistics of its category , quantity and biomass were processed according to different seasons : Spring (April - May) , Summer (June - August) and Autumn (September - October). The seasonal fluctuation of small mammals community in Yan'an plantation region was analyzed based on variables like the biomass , the Shannon index of species diversity , the evenness and dominance ; choosing biomass as the index of dominance of small mammals , the seasonal fluctuations of small mammals’dominance and its performance in different habitat were analyzed. The results were as follows : Nine species of three families and two orders of small mammals were found to exist in the region , the Ochotona daurica and the Myospalax fontanieri ca that closely correspond to the seasonal fluctuations of population biomass. In Yan'an plantation region , the seasonal fluctuation of the community biomass was determined by that of the dominant species ; The seasonal fluctuations of both the rare and common species together determined seasonal differences in species variation and number. The nine different species in the Yan'an plantation district existed in different spatial-temporal location. Only one species , The Myospalax fontanieri cansus , existed throughout the Yan'an plantation district all year round. The Ochotona daurica is especially dominant during the summer and fall seasons in the locust plantation area and weeds and shrubs area.

Key words: Yan'an plantation, Small mammal, Seasonal fluctuation, Habitat, Dominance