Spatial-temporal Variation of NDVI in the Growing Season and Its Sensitivity to Climatic Factors in Changbai Mountains

In order to reveal the response of mountain ecosystem to climate change,the spatial-temporal distribution of vegetation variation in the Changbai Mountains was investigated by using the 10-day SPOT/VGT NDVI data from 2000 to 2009.Combining the meteorological data,we discussed the relationship between NDVI and climatic factors and time lags of vegetation variation response to climate change.The results are shown as follows.1) NDVI increased from 2000 to 2009 in Changbai Mountains.The NDVI increased and decreased area covered about 83.91% and 16.09% of the whole study area respectively.The increased area was mainly distributed on the northern and western slopes,while the decreased area was distributed on the southern slope.The growth rate of NDVI centralized 0-0.006 /a.2) The change rate of NDVI varied by seasons and vegetation types.The peak of NDVI slope appeared in May and September,but no increase,even a little decrease was observed in July;3) There was a significantly positive correlation between NDVI and climatic factors(temperature and precipitation),and NDVI had a closer correlation with temperature than with precipitation for the three vegetation types.The results also revealed that a correlation between NDVI and temperature in tundra zone was stronger than that in the Korean pine-broadleaved mixed forest(700-1100 m) and coniferous forest(1100-1700 m),which indicated that vegetation at higher elevation is more sensitive to temperature change;4) The correspondence between NDVI and climatic factors had a marked time lag for 10-20 days for the whole study area.Different vegetation types had different time lags.The response of NDVI in tundra zone to climatic factors had a time lag of about 10 days,while in the two forests mentioned above,the response had a time lag of about 20 days.