关键词: 沙化土地, 光谱特征, 光谱响应机制

Abstract:

In recent years, sandstorm weather and its impact on environment and human health has attracted more and more attention. Researches on related domain have shown that desertification of arid and semi-arid regions has provided rich source for the formation of sandstorm weather. For this reason, to protect the large eco-environmental vulnerable area in North China from being desertified or degraded and to slow down the desertification process of the said area have become highly important and meaningful in practice. In order to do this, basic information about soil, vegetation and other features are indispensable for the study of land desertification. Field spectral data as one of these basic data sets can provide some valuable information about land desertification. Along with other data, they are useful in monitoring and classifying land desertification in certain areas. It also can be helpful to the study of the dust source of sandstorm weather. This article focuses on the frequently occurred sandstorm weather since the 1990s and the serious land desertification in North China and Beijing region, taking dry farming area,intertock area of farming and pasturing and pure pastoral area around Beijing as study areas. Fengning in Hebei province, Duolun and Xianghuangqi in Inner Mongolia have been selected as representatives of the above mentioned three areas. Field spectrum data of different land-cover and different desertified land had been measured using the ASD FieldSpec FR instrument in those study areas. Analyses and comparisons of processed field spectrum data of degradations to different degrees and degradations to same degrees in different seasons or with various vegetation cover rates have been done respectively. Farmland with different crops have also been measured and analyzed. According to the analyses of the sampled spectrum data, the spectrum characters and their responding mechanisms had been discussed. The conclusion is that soil water content, types of grass, height of grass, grass coverage and growth period of vegetation are related to the average spectrum characteristics of the desertified land. Spectrum curves vary with changes in environmental factors. Studies of soil and vegetation spectrum characteristics should be taken as further reference for the study of desertified land. Spectrum curves also changed with annual and seasonal vegetation growth. Thus the accumulation of long-term field spectrum data is more important and necessary.

Key words: desertification land, spectrum characteristic, spectrum responding mechanism