Relationships between tree growth and NDVI of grassland in the semi-arid grassland of north China

This study explores the relationships between the Normalized Difference Vegetation Index (NDVI), recorded above-ground grass biomass and tree-ring width index of relict Meyer spruce (Picea meyeri Rehd. et Wils.) forest in the typical steppe, north China. The average NDVI in May, June and August derived from an area of 0.5°×0.5° shows a large correlation with measured above-ground production, indicating that NDVI can reflect the approximate variability of above-ground biomass in the typical steppe. The integrated NDVI from 20 May to 10 July also exhibits high agreement with tree-ring width series of Meyer spruce from 1982 to 1994, which is attributed to their common response to precipitation in the previous August-October and current May. This study provides a basis for linking remotely sensed NDVI of grassland to tree growth in semi-arid grassland.