Simulation and variation pattern of vegetation phenology in Northeast China based on remote sensing

By using 1982-2003 GIMMS-NDVI data and with the help of GIS spatial analysis, the NDVI time-series data of different vegetation types in Northeast China were extracted. In the meantime , the phenological phases of the vegetation types were simulated by Logistic function , with their variation trends in 1982-2003 analyzed. It was shown that the beginning dates of vegetation growth seasons in needle-leaf forest , broadleaf forest , grassland , meadow , and swamp were advanced , and the lengths of the growth seasons were prolonged , being more obvious in swamps , followed by in needle-leaf forests. On the contrary, the beginning dates of vegetation growth seasons in needle-leaf and broadleaf mixed forest , shrub , grassland , and farmland were delayed , and the lengths of the growth seasons were shortened , being more obvious in farmland , followed by in grassland. The ending dates of the growth seasons appeared inconsistent , being delayed in needle-leaf forest and swamp , slightly advanced in broadleaf forest , grassland , and meadow , and advanced in needle-leaf and broadleaf mixed forest , shrub , grassland , and farmland , especially in shrub.