Dynamic Change Of Vegetation And Phenology Response To Climate Change In Gansu Province During 2001-2015

The geographical environment and climate types in the inland gansu province are rich and diverse,which is an important area for the study of vegetation type diversity,and also an ideal area for studying vegetation response to climate change.In order to discuss the level of vegetation cover response to climatic change under complex environment,this text take Normalized Difference Vegetation Index and vegetation phonological parameters as the breakthrough point,extracting NDVI of Gansu province and land surface phonological parameters by using Modis09Q1 remote sensing data set of 2001-2015 and Timesat at Matlab platform,analysing tendency of temperature,precipitation,NDVI and phenology by using linear regression analysis and Sen's slope,analyzing the level of NDVI,phenology response to change of temperature and precipitation by using Pearson Correlation Coefficient and Mann-Kendall Coefficient test.Exploring spatiotemporal variation characteristics of vegetation NDVI and phenology and its condition response to climatic factors is beneficial to know vegetation distribution and the level of different type of plant NDVI response to phenology.Through this,we can provide with gist to maintain well ecological environment under climate change.The main conclusions are as follows:(1)During the period of 2001-2015,the average temperature scope in Gansu Province is 5.03-5.89?,The general pattern of temperature distribution is the gradual increase of temperature from southwest to northeast,during the past 15 years,the temperature chan-ge tends to be stable and fluctuates within a certain range.The annual precipitation range in Gansu province is between 75 mm and 692 mm,and the distribution pattern of precipitation is gradually reduced from the southeast to the northwest.The average annual precipitation in Gansu is increasing by-7.94mm/a.(2)During the period from 2001 to 2015,the annual average NDVI value in Gansu province increased from the northwest to the southeast,and NDVI in most areas of NDVI was on the growth trend.Only NDVI of 5.8% of Gansu province was in decline.According to the time scale,the overall average NDVI in Gansu is on the rise,and the annual average of all vegetation types in NDVI is also on the rise.(3)In most regions of Gansu province,NDVI has a negative correlation with temperature,which is positively correlated with precipitation.The average annual NDVI and precipitation of all vegetation types in Gansu province are positively correlated,among which grassland,alpine vegetation and desert are more sensitive to precipitation.Grassland,cultivated vegetation,desert and other vegetation were negatively correlated with temperature,and the remaining vegetation types were positively correlated with temperature,and the swamp was the most sensitive to temperature.In terms of seasonal scale,spring is the season with the most close relationship between vegetation type NDVI and temperature and precipitation.(4)In most of the regions in Gansu province the SOS range is 100 days to 120 days,and the EOS range is 330 days to 350 days,and LOS ranges from 100 days to 260 days.During the period from 2001 to 2015,there was no significant change in SOS in Gansu province.The EOS was significantly delayed,and LOS significantly increased.In terms of phenological parameters of different vegetation types,SOS period of alpine vegetation,other vegetation gradually postponed,SOS period of meadows,marshes,grassland,cultivated vegetation's change is not big,SOS period of brush,broad-leaved and coniferous forest gradually ahead of time;EOS of all vegetation types were delayed;LOS of all vegetation types in the study area showed an increasing trend.(5)The negative correlation between SOS and spring and winter is significant,indicating that the growth of vegetation will be accelerated due to the temperature rise,and the increase of winter temperature will bring the SOS forward.SOS in some areas of precipitation inhibits plant growth,and in some areas may promote plant growth;EOS is more sensitive to temperature changes in cold regions than in other regions.In autumn and summer,the area ratio of EOS and temperature is higher,indicating that the increase of autumn temperature will delay the arrival of EOS in most area.In spring and summer,there is a significant positive correlation with LOS,indicating that the temperature will promote the growth of vegetation in most area.The winter temperature is negatively correlated with the grassland LOS,which indicates that the increase of winter temperature may inhibit the growth of grassland in the next year.