The Research Of The Phenology Change And It's Response To Geographical Elements In Qilian Mountains From 1982 To 2014

Vegetation, as the main body of terrestrial ecosystem, It's change has an obvious response to the environment, and it is a comprehensive indicator of the integrating instrument of the global change and the change of landscape ecological environment. Qilian mountain is an important ecological area in Northwest China. Based on the GIMMS and MODIS NDVI data set, reconstructed NDVI time series data using Savitzky-Golay filter, and extracted the phenology of different vegetation using double logistic fitting method(growing season start date, end date and growth of Ji Changdu), the spatial and temporal change trends and it's response to topographic factors were analysised in Qilian Mountains from 1982 to 2014. In addition, the correlation between different vegetation phenological parameters and climate factors such as temperature and precipitation were studied using partial least squares regression from 2000 to 2014. The aim is to understand fully the changes of phenology of different vegetation and it's receponse to climate change in the study area in recent 33 years, so as to provide scientific basis for agricultural production planning, rational grazing and constructing the ecological environment and understand furtherly influence of regional climate change to different vegetation phenology changes under large scale.(1) Vegetation changes to green gradually from southeast to northwest in growing season start date(SOS), and changes to yellow gradually from the northwest to the southeast in growing season end date(EOS), that show the characteristic which the vegetation growing season(LOS) is longer in southeast region than in northwest region and it is longer in high altitude region than in valley region. The SOS is mainly focused on the first 120~160 days, the EOS mainly concentrated in the first 240~280 days, and the LOS mainly concentrated in the 80~150 days.(2) The SOS and EOS appeare overall ahead volatility trend in Qilian mountain from 2000 to 2014 and from 1982 to 2006, but the LOS show a fluctuating trend of shortening from 1982 to 2006 and a fluctuation trend of extending from 2000 to 2014. The region where the early of SOS and EOS is not obvious mainly focus on mountain, but the region where the delay of SOS and EOS is not obvious manly focus on valley, which reduce the delay of LOS in mountain is not obviouse and the early of LOS in valley is also not obvious. All in all, the change of plant phenology does not vary significantly.(3) Phenological parameters of different vegetation are not identical in Qilian Mountains, that SOS of broad-leaved forest vegetation is the earliest but SOS of desert vegetation is the latest; and that EOS of cultivated vegetation is earlier while EOS of desert vegetation and swamp vegetation are later, and that LOS of broad-leaved forest and coniferous forest vegetation are longer but LOS of desert vegetation and mountain vegetation are short. With the climate change, SOS and EOS of different type vegetations appeared in advance or delay with fluctuation, which the variation of swamp is maximum, and LOS of meadow, shrub, coniferous forest and cultivated vegetation show delay. According to the distribution of vegetation phenology changes, the advance or delay of SOS and EOS are not obvious, and the shortening and prolong of LOS is also obvious.(4) In Qilian Mountains, Variation of phenological parameters is closely related to topographic factors. SOS appear an obvious delaying trend with the increase of altitude from 2700 to 3250 m, the same as EOS from 2500 to 3250 m, but LOS appear a shortening trend with the increase of altitude from 2500 to 4500 m. Phenological parameters in slope bwteen 10 to 25 degrees do not obvious change, but SOS and EOS in slope between 0 to 6 degrees show an obvious trend and LOS show an obvious delay trend with the increase of slope, and phenological parameters show violent fluctuation in slope more than 45 degrees. It is earlied for SOS in northwest and north slope, and it is later for EOS in south, southwest and west slop, and it is longer for LOS in west, northwest, north, northeast and east slop.(5)Variation of phenelogical parameters is obviously related to climate factor in Qilian Moutation. It is significant negative correlation between SOS with temperature from March to May, which indicate the increase of temperature in spring reduce to advance of SOS. Except for September when it is significant positive correlation, they are basically negative correlation between EOS and temperature, that indicate the increase of temperature reduce to delay of EOS. It is negative correlation between winter precipitation a year ago with SOS, which indicate the increase of it reduce to advance of SOS, the same as the increase of spring precipitation reduce to advance of SOS. It is positive correlation between precipitation from Februry to April or from July to September with EOS, that indicate the increase of precipitation in spring reduce to delay of EOS. The correlation between phenological parameters of different vegetation with temperature and precipitation are different.