GRASSLAND DESERTIFICATION AND MICRO-METEOROLOGICAL CHANGES IN NAIMAN
- 出版年：1998
- 作者：L.I Sheng-gong；ZHAO Ha-lin；HE Zong-ying；CHANG Xue-li；Yoshinobu HAROZONO
- 单位1：Institute of Desert Research，Chinese Academ y of Sciences，Lanzhou
- 语种：英文
- 作者关键词：Grassland；Grazing intensity；Micrometeorology；Desertification
- 起始页：359
- 总页数：7
- 刊名：中国沙漠
- 是否内版：否
- 刊频：季刊
- 创刊时间：1981
- 主办单位：中国科学院兰州沙漠研究所；林业部兰州沙漠研究所
- 主编：夏训诚
- 地址：北京市东黄城根北街16号
- 邮编：100717
- 卷：18
- 期：4
- 期刊索取号：P\222.06\141-1
- 核心期刊：中国自然科学核心期刊
摘要
Overgrazing is one of the primary causes for desertification in the semiarid zone of China. A grazing experiment in Naiman (N42°55′,E120°42′,405m asl), Inner Mongolia, China was conducted to elucidate the desertification mechanisms, especially the initiation of desertification of grassland resulted from overgrazing. The experiment field included four plots, i.e., non grazing, lightly grazing, moderately grazing and over grazing plots, in which grazing sheep number differed from 0,3,6, and 9, respectively. Micro meteorological elements were observed at these plots. The obtained data were analyzed using the Bowen ratio energy balance method and aerodynamic gradient method. The results show that:1)Ground surface reflectivity (albedo)increases with grazing intensity, e.g., albedo of the overgrazing plot has increased from 0 20 at the beginning of the experiment in 1992 to 0 28 in 1994. The overgrazing plot has been desertified. Thus, albedo becomes an important indicatior of grassland desertification. 2)Partitioning of net radiation exhibits distinct patterns among the four plots that is the results of interplay of albedo and in situ vegetation. The net radiation and contribution of latent heat flux tend to decrease due to increasingly grazing intensity. Heavy trampling by sheep also affects heat budget over the ground surfaces. 3) Wind profiles above the ground of each plot have different structures. Much stronger wind shear on the overgrazing surface is a significant driving forcing resulting in intense sand flow activities on which desertification processes are based. 4) Safe grazing capacity of the studied grassland during growing season is proposed to be 3～4 sheep or sheep equivalents per hm 2. according to the experiment and the plant community dynamics