Responses of vegetation phenology in Northeast China to climate change

Based on the 1982-2003 GIMMS-NDVI and meteorological data, and by using GIS spatial analysis and statistical methods, the responses of vegetation phenology in Northeast China to climate change were analyzed. From 1982 to 2003, the annual mean temperature in Northeast China had an increasing trend, while the annual mean precipitation was in reverse. The elevated temperature in spring advanced the beginning dates of the growth seasons of the vegetations in coniferous forest, coniferous and broadleaved mixed forest, broadleaved forest, meadow, and swamp (P <0. 05), while the precipitation in spring only postponed the beginning date of the growth season of the vegetation in coniferous forest (P <0. 05). Temperature had less effects on the ending dates of the vegetations growth seasons except that the declined temperature in autumn advanced the ending dates of the growth seasons of grasses ( P < 0. 05). Compared with temperature, precipitation had more effects on the ending dates of the vegetations growth seasons. Due to the decreased precipitation in autumn, the ending dates of the growth seasons of the vegetations in coniferous and broadleaved mixed forest, grassland, and cropland were advanced ( P < 0. 05) while those of the growth seasons of grass-forb communities advanced \P <0. 05). The ending dates of crop growth seasons were advanced by the declined precipitation in summer and September ( P < 0. 05). The warmer temperature in spring prolonged the growth seasons of the vegetations in broadleaved forest and swamp ( P < 0. 05). The declined precipitation in spring shortened the growth seasons of shrubs (P <0. 05), while the increased precipitation in summer prolonged the growth seasons of grass-forb communities and crops (P <0.05).