关键词: 植物生活型, 碳, 氮, 气候因子, 磷, 荒漠植物, C4植物, C3植物, 生态化学计量

Abstract: Vegetation plays a vital role in terrestrial ecosystems. The frequency of drought event has gradually increased in recent years, which has negative impacts on vegetation growth. This study evaluated the response of vegetation growth in Northeast China to drought based on the correlation between normalized difference vegetation index (NDVI) and standardized precipitation evapotranspiration index (SPEI) from 1982 to 2015. The results showed that the maximum correlation coefficient (R_max) between NDVI and SPEI in annual and seasonal scales was the largest in the grassland region of Inner Mongolia (western Northeast China), followed by the Changbai Mountains (eastern Northeast China) and the Northeast Plain (centraleast part of Northeast China). The temporal scales with R_max were SPEI-12 and SPEI-24, indicating that drought has long lag effects on vegetation. The NDVI in growing season and summer was most sensitive to SPEI, and then decreased in spring and autumn. The NDVI in May-July had high proportion of significant correlations with SPEI-24, while NDVI in August-October exhibited high proportion of significant correlations with SPEI-06. Different vegetation types responded differently to drought. Forest NDVI showed a negative correlation with SPEI in different months and at different scales, while grasslands and croplands mainly showed positive correlations.

Key words: desert plant, C3 plant, nitrogen, phosphorus, plant life form, climatic factor, carbon, C4 plant, ecological stoichiometry.