阿拉善荒漠啮齿动物优势种觅食活动对不同放牧方式的响应

Feeding behavior of sympatric rodents in the Alxa Desert in response to different grazing patterns

阿拉善荒漠脆弱生态系统对人为干扰反应较敏感,不同放牧方式导致该生态系统的植被资源类型、密度、分布、盖度、基质以及动物感知捕食风险等各不相同。同域分布的荒漠啮齿动物在不同干扰下的觅食差异性对于荒漠地区生物多样性的维持具有重要意义。本文于2020年通过红外相机陷阱技术对阿拉善荒漠区同域共存的三趾跳鼠(Dipus sagitta)、五趾跳鼠(Orientallactaga sibirica)和子午沙鼠(Meriones meridianus)3种优势鼠种在3种不同放牧方式下的摄食行为进行观测,结果显示:(1)不同放牧方式下3种啮齿动物优势种的种群密度与摄食行为成正比,放牧增加了五趾跳鼠种群密度,其摄食行为也在放牧强度大的生境中占比更多;子午沙鼠在放牧强度较小且植被盖度较高的生境中种群密度较高,摄食行为也多集中于此;三趾跳鼠在不同放牧方式下种群密度差异不大,相对来说在放牧强度更大的生境中花费的觅食努力更大;(2)相同放牧方式下,子午沙鼠面对食物会采取“觅食+取食+贮食”相结合的摄食策略,而三趾跳鼠和五趾跳鼠更倾向于“觅食+原地取食”的摄食策略。由此表明,尽管不同鼠种具有差异化的摄食策略,但是它们的觅食行为会受到放牧方式的影响,而这种影响是通过改变啮齿动物种群密度、栖息地植被和土壤特征等环境因子造成的。

The fragile ecosystem of the Alxa Desert is sensitive to human disturbance and different grazing patterns lead to different vegetation resource types,density,distribution,coverage,substrate and animal perception of predation risk.The feeding differences of desert sympatric rodents under different grazing disturbances are of great significance for the maintenance of biodiversity in desert areas.In 2020,infrared camera trap technology was used to observe the feeding behavior of three dominant rodent species,namely Dipus sagitta,Orientallactaga sibirica,and Meriones meridianus,which coexisted in the same area in the Alax Desert.The results showed that:(1)the population density of the dominant rodent species was positively related to their feeding behavior under different grazing patterns.Grazing increased O.sibirica population density,and its feeding behavior also accounted for more in grazing-intensive habitats.M.meridianus had higher population density and more feeding behavior in habitats with low grazing intensity and high vegetation coverage.D.sagitta devoted more foraging effort in more grazing-intensive habitats.(2)Under the same grazing mode,M.meridianus adopted a combined feeding strategy of‘foraging+feeding+storage’,while D.sagitta and O.sibirica adopted the feeding strategy of‘foraging+feeding’.These results indicated that the feeding behaviors of rodent species with various feeding strategies were affected by grazing patterns according to changing environmental factors such as rodent population density,habitat vegetation,and soil.