Monitoring desertification processes in Mongolian Plateau using MODIS tasseled cap transformation and TGSI time series

Abstract

Most remote sensing studies assess the desertification using vegetation monitoring method. But it has the insufficient precision of vegetation monitoring for the limited vegetation cover of the desertification region. Therefore, it offers an alternative approach for the desertification research to assess sand dune and sandy land change using remote sensing in the desertification region. In this study, the indices derived from the well-known tasseled cap transformation (TCT), tasseled cap angle (TCA), disturbance index (DI), process indicator (PI), and topsoil grain size index (TGSI) were integrated to monitor and assess the desertification at the thirteen study sites including sand dunes and sandy lands distributed in the Mongolian Plateau (MP) from 2000 to 2015. A decision tree was used to classify the desertification on a regional scale. The average overall accuracy of 2000, 2005, 2010 and 2015 desertification classification was higher than 90%. Results from this study indicated that integration of the advantages of TCA, DI and TGSI could better assess the desertification. During the last 16 years, Badain Jaran Desert, Tengger Desert, and Ulan Buh Desert showed a relative stabilization. Otindag Sandy Land and the deserts of Khar Nuur, Ereen Nuur, Tsagan Nuur, Khongoryn Els, Hobq, and Mu Us showed a slow increasing of desertification, whereas Bayan Gobi, Horqin and Hulun Buir sandy lands showed a slow decreasing of desertification. Compared with the other 11 sites, the fine sand dunes occupied the majority of the Tengger Desert, and the coarse sandy land occupied the majority of the Horqin Sandy Land. Our findings on a three or four years' periodical fluctuated changes in the desertification may possibly reflect changing precipitation and soil moisture in the MP. Further work to link the TCA, DI, TGSI, and PI values with the desertification characteristics is recommended to set the thresholds and improve the assessment accuracy with field investigation.

Desertification Information Extraction Based on Feature Space Combinations on the Mongolian Plateau

“…More serious desertification corresponds to rougher the surface soil particle composition. Therefore, TGSI (topsoil grain size index) is recommended as an evaluation index of land degradation [20,21]. Lamchin et al used NDVI, TGSI, and albedo as representative indicators of vegetation biomass, landscape pattern, and micro-meteorology, respectively.…”

Desertification Information Extraction Along the China–Mongolia Railway Supported by Multisource Feature Space and Geographical Zoning Modeling

“…Different degrees of desertification produce different topsoil textures, the more serious the desertification, the rougher the topsoil particle composition [22]. Therefore, topsoil grain size index (TGSI) can be used to represent the size of soil surface particles and as an evaluation index for desertification [23]. Munkhnasan et al took NDVI, TGSI, and Albedo as the representative indexes of vegetation biomass, landscape pattern, and micrometeorology, respectively, to obtain a 30-m resolution map of desertification and completed the dynamic analysis of desertification in Hogno Khaan nature reserve, Mongolia [24].…”

Effects of Long-Term Vegetation Restoration on Distribution of Deep Soil Moisture in Semi-arid Northwest of China

“…Desertification is one of the hot ecological issues in the world, and China is one of the countries with the most serious desertification. The soil moisture in arid and semi-arid areas of northwestern China has attracted much attention due to the rapid expansion of desertified land (Yu et al 2018;Liu et al 2018a). Desertification will lead to a series of ecological and environmental problems, such as soil structural damage, nutrient loss, reduction of soil biodiversity, and soil texture coarsening.…”