Drought impacts on vegetation changes in North China

The 13-year (2001 2013)time series of   Moderate-resolution Imaging Spectroradiometer
 (MODIS) Normalized Difference VegetationIndex  (NDVI) products and the Palmer Drought Severity Index
 (PDSI) calculated from meteorological station data were used to analyze spatial-temporal variations in NDVI,
evolution characteristics of PDSI in North China and in three kinds of major land type areas.Themulti-scale
 correlation between NDVI and PDSI was also calculated to explore drought impacts onvegetation changes.It
was found that  NDVI varied in differentareas, with higher NDVI in south east and center compared to
 north west. From  2001 2013,vegetation activities in North China showed an increasing trend, and the
 increasing trend was most significant in the autumn.The annual average PDSI showed an increasing trend,
 especially in the autumn.There was asignificant positive correlation between annualvariation of vegetation and
 drought ,and droughts had a strong influence on vegetation growth.Seasonally, a positive correlation between
 variation of vegetation and drought was the most significant in the summer.Vegetation growth was the most
 susceptible to drought in summer.Analysis of 16-day data showed that NDVI anomaly was more suitable than
 NDVI to characterize relationship between vegetation growth and drought in North China.