Abstract: Grassland agriculture is an important economic foundation in northern Tibet.Improving measures,such as enclosure of the grassland,supplementary sowing,establishment of high-quality artificial grassland by mixed sowing,have been investigated and implemented in some demonstration zones by the government and researchers.This paper using the single-temporal data in July 2006 and time-series dataset in 2008 derived from CBERS-02 satellite,together with the geographic bounds of artificial and natural grasslands and the region of free-delaying-banning grazing grasslands measured by GPS,vegetation cover and growing characteristics of different types of grasslands were monitored and reported.The mean value,standard deviation,extreme value and dominant index(DI) were taken as indices to analyze the vegetation growth states.Results showed that: the best,the poorest and average vegetation growth of artificial grassland all exceed that of the natural grassland,but the vegetation cover evenness of the former is worse than the latter;the vegetation growth of banning grazing,warm-season delaying grazing and free grazing grasslands incrementally decreased;cover evenness of warm-season delaying grazing before grazing basically remained the same with that of banning grazing.Additionally,research proved that 3S technology is an effective approach for dynamic and extensive monitoring grassland coverage.

Key words: Grazing system, CBERS-02, Vegetation index, Artificial grassland, Banning grazing, Delaying grazing, Remote sensing

摘要： 草地畜牧业作为藏北地区的重要经济产业,一直以来政府和科研人员致力于通过试验示范区探索和推广天然草场围封改良、补播改良、优质混播人工草地建植等措施来提高草场利用率和维持草地生态系统的可持续发展。基于GPS实地测量人工、天然草场以及自由放牧、暖季休牧和禁牧不同放牧制度的草场试验样地范围,以2006年7月及2008年年内时间序列的CBERS-02星数据作为遥感数据源,分别监测人工与天然的休牧草场、天然的自由放牧-暖季休牧-禁牧草场的植被长势。利用归一化植被指数(NDVI)和差值植被指数(DVI)的均值、标准差、极值及优势度反映不同草场植被长势、覆盖均匀度等情况。结果表明:人工补播的草场植被普遍长势、最佳长势及最劣长势均优于天然草场,但人工草场的覆盖均匀度不及天然草场;天然禁牧、天然暖季休牧、天然自由放牧草场长势依次递减;休牧在九月中旬放牧之前与禁牧草场的植被覆盖均匀度基本保持一致,两者的NDVI标准差远低于自由放牧草场,但休牧草场在放牧之后,植被均匀度遭到破坏,NDVI标准差介于禁牧与自由放牧草场之间。此外,该研究采用3S技术,从另一角度有效地实现了对草场覆被长势的动态、宏观监测。

关键词: 放牧制度, 中巴资源卫星, 植被指数, 人工草地, 禁牧, 休牧, 遥感