草原植被长势遥感监测研究进展

The Progress of Remote Sensing Monitoring for Grassland Vegetation Growth

草原植被长势监测是草原监测的重要领域,它能从宏观上揭示草原的生长状况及其动态变化,从而为草原科学管理提供快速、准确的参考依据。目前长势监测主要利用遥感的方法,即选择归一化植被指数NDVI作为反映植被生长状况的指标,方法有同期对比法、植被生长过程曲线法、直接监测法。本文在总结草原长势监测进展与方法的同时,指出了其中存在的问题——监测中过分依赖NDVI、不区分草原类型而使用同一种方法进行监测;对未来发展方向做了展望——监测中选用适宜植被指数、监测方法,分区域、分类型的监测长势,提高监测精度,将长势监测与草原产草量、生产力结合,为牧民生产提供指导。

Grassland vegetation growth monitoring is an important field of grassland monitoring, which macro-scopically reveals growth status and dynamic changes of grassland, providing instantaneous and accurate refer-ences to scientific grassland management. At present, remote sensing is widely applied in growth monitoring, which means choosing NDVI as the index to reflect vegetation growth condition. This method includes periodi-cal comparative, vegetation growth process curve and direct monitoring. Direct monitoring is more complex in using because it needs build relationships to plant physiology and ecology parameters; vegetation growth pro- cess curve and direct monitoring is simple, but they cannot classify the growth of vegetation; periodical compar- ative not only reflects the space of growth, it also reflects growth change in time series, facilitates contrast in many years. This paper summaries the methods and progress of grassland growth monitoring at home and abroad. The main remote sensing data includes AVHRR, MODIS, microwave data and ultrasonic data, and for-eign growth monitoring focuses on the production forecast and against disaster waming. Domestic growth moni- toring pays more attention to periodical comparative and phenophase monitoring and does few studies on real time monitoring. Then the paper points out the existing problems of growth monitoring, such as over-depen-dence on NDVI and applying the same monitoring method without consideration about the grass types. The prospects come in the end that by choosing the appropriate vegetation index, monitoring methods and monitor-ing growth in different zones and types to improve the precision of monitoring, as well as combining growth monitoring with grassland plant yield and grassland productivity will hopefully provide nomadic production with scientific guidance. Besides, this paper introduces three key fields in vegetation growth, which are vegeta-tion growth hierarchies, determination of key vegetation growth period and main influencing factors of growth. Temperature and precipitation are the main factors driving the growth of vegetation, and the role of precipitation is the most important one.