草地植被覆盖度变化及其驱动力 ——以甘南藏族自治州玛曲县为例

GRASSLAND COVERAGE CHANGES AND THE DRIVING FORCES ——A CASE STUDY OF MAQU COUNTY

关键词:  玛曲草地 植被覆盖度 驱动力

Key words:  Maqu grassland  vegetation coverage  driving force

摘要:

草地生态系统对区域的生态安全和可持续发展起着重要作用。植被覆盖度是衡量草地生态环境的 重要指标，其变化规律对生态环境建设和水土流失治理工作具有重要意义。通过对玛曲草地覆盖度数据进 行统计分析，得出以下结论:（1）2000～2010年，草地覆盖度整体呈减小趋势，并具有阶段性特征;草地 植被普遍存在退化趋势，低覆盖草地植被只局部有修复现象，出现稳定存在趋势。（2）玛曲草地覆盖度变 化的驱动因子主要有:光、热、水等自然因子，超载放牧以及社会经济因子。水热不匹配增加了草地蒸散 量，影响了植被的生长，进而影响了植被覆盖度的变化;鼠虫害对牧草和土壤的结构产生影响，致使草地 生态环境进一步恶化，降低了草地生产力;非法采药挖药，严重破坏了草地植被的完整性，这在一定程度 上是该地区植被覆盖度变化的重要因素之一;在经济利益的驱使下，牛羊数量逐年增多，草地负荷加重， 亦导致了植被破坏和植被覆盖度的降低。

Abstract:

Grassland ecosystem plays an important role in regional ecological safety and sustainable development. Vegetation coverage is an important indicator for weighing grassland ecological environment. Statistics was used in this paper to analyze the grassland coverage changes in Maqu county. The results showed that: 1）The grassland coverage displayed an decreasing tendency with stage characteristics from 2000 to 2010.The grassland coverage generally had continuously degenerated， while the low coverage grassland was recovery in some areas.2）The nat- ural factors such as sunlight，heat，water shortage， together with the human activity impact such as overload herds and socio-economic were the dominant driving factors. The thermal mismatch increased grass evapotranspiration， and hence affected the growth of vegetation， thereby affected the vegetation coverage change; the changes of forage and soil structure by rodents and insects deteriorated grassland ecological environment and reduced the grassland productivity; herbs digging seriously undermined the integrity of grassland vegetation; heavier loads reduced vegeta- tion and vegetation coverage.