1.Chinese Academy of Meteorological Sciences, Beijing 100081, China 2.College of Life Sciences, Hebei University, Baoding 071002, China 3.Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
摘要： 介绍了生物土壤结皮遥感光谱特性和遥感监测方法研究进展。主要论述了生物土壤结皮光谱的变异性与土壤水分的关系，分析了生物结皮对区域植被遥感解译的影响。干湿生物结皮的光谱差异以及土壤浅表层水分的更替会造成植被动态的错误解译和生态系统生产力的过高估计，经研究得出，100%盖度的干湿苔藓结皮NDVI之差大约0.35(干苔藓结皮0.30，而湿苔藓结皮0.65)，100%盖度干湿藻类结皮NDVI之差大约0.15(干藻类结皮0.15，而湿藻类结皮0.30)，最大值合成法(max value composite, MVC)会使分布有相当盖度的苔藓结皮的区域的NDVI求解受降水的影响很大，会造成该区域短时间内NDVI不稳定性，而影响植被动态解译。综合国内外研究认为，生物结皮研究中，除了考虑不同土壤水分下生物结皮的光谱外，还应考虑生物结皮光谱的季节差异。
关键词：生物土壤结皮;遥感;光谱;苔藓;地衣
Abstract：The Biological Soil Crusts(BSC) (also known as organic or microphytic crust) can be formed by different combinations of microphytic communities including mosses, lichens, liverworts, algae, fungi, cyanobacteria (=blue-green algae or Cyanophyta), as wellas bacteria.Large areas of sand fields in arid and semi-arid regions are covered by BSC.Remote sensing distinction should be made between physical and biogenical crust formations.It was reviewed the advances of domestic and overseas studies of BSC spectral characteristics, as well as spectral reflectance measurement in situ of our workgruop.When the BSC is wet, it turns green, a notable change in the reflectance curve occurs.The wet BSC’s spectral reflectance curve is similar to those of the higher plants and therefore may lead to misinterpretation of the vegetation dynamics and to overestimation of ecosystem productivity.This spectral feature produces a much higher NDVI value for the wet moss BSC than for the dry moss BSC(0.65 vs.0.30 units, respectively), a higher NDVI value for the wet algae BSC than for the dry algae BSC(0.30 vs.0.15 units, respectively).The "maximum value composite" (MVC) technique is used to eliminate the effect of clouds and haze from vegetation maps.Misinterpretation of the vegetation dynamics could be more severe due to the MVC technique used to compose the global vegetation maps in the study of vegetation dynamics.But relatively limited research has been conducted to investigate the spectral characteristics of BSC change with different moisture conditions and under different seasons.More research works could be considered in spectral characteristics of BSC.The researches would be useful for detecing and mapping BSC, from remote sensing imagery.It also is to the advantage to employ Vegetation Index wisely.
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