NDVI-based increase in growth of temperate grasslands and its responses to climate changes in China

This study analyzes the temporal change of Normalized Difference Vegetation Index (NDVI) for temperate grasslands in China and its correlation with climatic variables over the period of 1982-1999. Average NDVI of the study area increased at rates of 0.5% yr(-1) for the growing season (April-October), 0.61% yr(-1) for spring (April and May), 0.49% yr(-1) for summer (June-August), and 0.6% yr(-1) for autumn (September and October) over the study period. The humped-shape pattern between coefficient of correlation (R) of the growing season NDVI to precipitation and growing season precipitation documents various responses of grassland growth to changing precipitation, while the decreased R values of NDVI to temperature with increase of temperature implies that increased temperature declines sensitivity of plant growth to changing temperature. The results also suggest that the NDVI trends induced by climate changes varied between different vegetation types and seasons. (C) 2006 Elsevier Ltd. All rights reserved.