黄河源区玛多县草地退化成因分析

对黄河区玛多县草地退化的自然和人为因素作了深入分析。结果表明，过度放牧是导致玛多县草地退化的主要原因，自20世纪80年代末期以来，玛多县温度和降水较历史平均水平均有较大幅度的提高，其中温度增加表现为明显的暖冬现象，降水增加集中在春夏两季，水热条件的变化是向着利于草地恢复的方向发展的，由于玛多县是一个纯牧业县，扩大畜群数量是经济增长的必然选择，加上人口压力和当地藏族居民的传统价值观，驱使牧畜数量不断扩大，并在70年代末达到最大值，此后长期维持过牧状态，造成草地持续退化，过牧在导致草地退化的同时，也为鼠类的侵入创造了条件，从而加强了退化过程。

Analysis of formation causes of grassland degradation in Maduo County in the source region of Yellow River

Natural and artificial factors of grassland degradation in Maduo County in source region of Yellow River were analyzed in this paper. The results showed that overgrazing was the major reason for grassland degradation. Compared with historical average, annual temperature and precipitation in Maduo had an obvious rise since the end of 1980s. Temperature rise concentrated in winter, and precipitation rise concentrated in spring and summer. Therefore, the change in water and heat condition was advantageous to grass growth there. Maduo was a county totally dependent on stock raising, and enlarging livestock population was the only choice for economic development. Together with the pressure of population growth and local Tibetan's traditional value, the number of livestock had been increased continuously, and finally reached summit in the end of 1970s. Since then, the grassland had been kept in the state of overgrazing and degradation, which also created favorable condition for the invasion of pikas, and thus sped up the process of degradation.