Quantitative Assessment of Land Degradation and Improvement Using Satellite NDVI Data: North China Pilot

摘要

As a pilot for a global assessment of land degradation and improvement, spatial patterns and temporal trends of green biomass at the interface between the Mu Us Desert and the Loess Plateau, North China, are analysed using 22 years of bi - monthly NOAA -AVHRR NDVI data. Average annual, growing season and non - growing season NDVI indicators were derived for each pixel and trends analyzed. Biomass increased over the period without close correspondence with rainfall; signs of declining green biomass are few. Correlations of the NDVI indicators and net primary productivity ( NPP) with annual rainfall are low to moderate, but higher with monthly rainfall. Rainfall - use efficiency, both computed as the ratio between NPP and rainfall (RUENPP), and as ratio between NDVI and rainfall (RUENDVI) increased at Yulin and slightly decreased at Dingbian. The results illuminate several recent researches on reclamation and improvement in the region.