鼠害在若尔盖草原沙漠化进程中的作用与机理

若尔盖草原是中国高寒湿润地区发生大面积沙漠化的典型案例，其沙漠化的成因及发展趋势一直受到极大关注。通过野外考察、遥感卫星影像解译等，着重探讨了鼠害在若尔盖草原沙漠化的形成和发展过程中的作用。结果表明：旱獭洞的分布与丘陵沙丘在坡度和坡向上有高度的相似性。地表致密草皮层发生机械性破坏，致使下伏松散沙暴露是若尔盖草原沙漠化的关键一步。旱獭洞的坍塌在草皮层的破坏过程中起到了至关重要的作用。草皮层破坏后，下伏松散沙被侵蚀，引起草皮层坍塌，导致古沙丘活化，形成流动沙丘。在此过程中，自然因素如风、降水、冻融、重力，人为因素如过牧、牲畜活动，都起到了不同的作用。小型鼠类如高原鼢鼠、高原鼠兔的严重鼠害区可以形成轻度沙漠化。

The Role and Mechanism of Rodents in Formation Processes of Aeolian Desertification in the Zoige Grassland

As a typical case in formation of aeolian desertification in alpine humid area in China, the Zoige Grassland has been paid great attention for its aeolian desertification. By means of field investigations, interpretation of remote-sensing images, this paper focuses on the role and mechanism of marmots (Marmota himalayana) in formation processes of aeolian desertification on the Zoige Grassland. The results show that the distribution of sand dunes and marmot burrows in hill slope are similar in slope gradient and slope direction. Destruction of turf is the key step in formation of aeolian desertification on the Zoige Grassland. As a kind of large-bodied underlying-dwelling rodents, the burrows digging behavior of marmots plays a vital role in destroying surface turf. Marmot burrow sites are usually located in open, herb-covered talus sunny slopes. The collapse of the large opening of burrows leads to destruction of turf and exposure of loose sands. The exposed loose sands are eroded away, causing collapse of turf which eventually leads to reactivation of fossil sands and formation mobile dunes. During this process, the natural factors such as wind, water, freezing-thawing process, gravitation, human factors, such as overgrazing, livestock activity, have played different roles. Digging of small-bodied animals such as Ochotona curzoniae and Myospalax baileyi can carry sands to the ground. In severe rodent damage area, the rodent mounds covered about 5% of ground and can classed as light degree of aeolian desertification.