NDVI Change And Its Correlation With Meteorological Factors In Tajikistan

This paper analyzes the spatial and temporal variations of NDVI and its correlation with meteorological factors using the data from MODIS and CRU during 2000—2013 based on the methods of maximum synthesis, trend analysis, correlation analysis, and partial correlation analysis. The results showed that:(1)The annual average NDVI in the central and western regions were higher than the eastern, the NDVI of lower altitude mountains and flat valley were larger than the high altitude mountain’s. Stability area was the largest, the slowly varying area was the second, and obviously varying area was the smallest.(2)The annual average NDVI of Tajikistan was on the rise in recent 14 years, with the increasing rate of 0.005/10 a. The vegetation cover was in good conditions from April to July, but was relatively poor in January and December. The range of NDVI variation was small in June and October, but it change greatly in November.(3)The annual NDVI of cultivated land, forest and shrub land all declined, while grassland showed a slight increasing trend. However, the monthly NDVI of cultivated land changed greatly, the forest, shrub land and grassland were very stable in June, and the variation was on the contrary in November.(4)The annual average temperature and precipitation were declined, at the tendency rate of-0.3 ℃/10 a and-29.1 mm/10 a. In the spatial distribution, the temperature decreased with the increasing of altitude, and the precipitation in the central areas was significantly higher than marginal areas.(5)In the annual scale, the annual average NDVI presented a strong positive correlation with the annual precipitation, and the average NDVI presented a strong positive correlation with the average temperature in winter. In the month scale, the correlation between NDVI and the average temperature had been significantly improved, and appeared a reversal phenomenon in the correlation between NDVI and precipitation. The influence of temperature in the correlation between NDVI and precipitation was greater than that precipitation in the correlation between NDVI and temperature. Weak correlation or unrelated areas between NDVI with precipitation and average temperature were the largest, and the strong negative correlation areas were very small.