Growing-season Trends Determined from SPOT NDVI in Changbai Mountains, China, 1999-2008

A wealth of remotely sensed image time series is now available to monitor vegetation dynamics over large areas.In this papert,he spatial pattern of three key vegetation phenological metrics,the start of growing season(SOS)t,he end of growing season(EOS),and the length of growing season(LOS)were inferred from the time series SPOT/NDVI data based on double logistic model in Changbai mountains,and the trends of them are assessed.The results show that the SOS of forests focus on dekad 10-12t,hat of grasslands and crop-lands start relatively late,they are in decad 13-14 and decad 14-15,respectively.The EOS of forests and grasslands range from 275th to 285th dayt,hat of croplands are early relatively,which are between 265th and 275th day.Thereforet,he LOS of forests,grasslands and croplands are 160-180 days,140-160 days and 110-130 days,respectively.The trends of phenophases have certain spatial discrepancy,which express that the LOS prolong in middle-eastern areas and shorten in northwestern areas.Then the derived phenological met-rics were validated by a few field observed data and some previous research achievements in the same area.