Resources Science ›› 2018, Vol. 40 ›› Issue (8): 1684-1692.doi: 10.18402/resci.2018.08.17

• Orginal Article • Previous Articles    

Diurnal asymmetry of temperature and its effect on NDVI in Loess Plateau

Liqun MA1(), Fen QIN1, Jiulin SUN2, Hao WANG3, Haoming XIA1()   

  1. 1. The College of Environment and Planning of Henan University, Kaifeng 475004, China
    2. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
    3. School of Civil Engineering and Architecture of Henan University, Kaifeng 475004, China
  • Received:2018-04-21 Revised:2018-07-04 Online:2018-08-25 Published:2018-08-10

Abstract:

In this paper, the meteorological observation data of 102 meteorological stations in the Loess Plateau and its surrounding areas in 1982-2015 were selected. The Normalized Difference Vegetation Index (NDVI) and vegetation type data were used. And the Mann-kendall (m-k) Nonparametric test method and the second-order partial correlation analysis were adopted. The time series change trend and spatial pattern in the growing seasonal minimum temperature (Tmin) and maximum temperature (Tmax) over the Loess Plateau between 1982 and 2015 were analyzed, and the effects of asymmetric warming on different vegetation type were discussed. The results show that: ① We found a persistent increase (P<0.01) in the growing seasonal Tmin and Tmax over the Loess Plateau between 1982-2015, whereas the rate of increase of Tmin was 1.6 times that of Tmax. ②The influence of diurnal asymmetry on vegetation dynamics showed an obvious difference, and NDVI and Tmin showed a more significant correlation than NDVI and Tmax in vegetative growth season. The effect of nighttime warming on NDVI in the Loess plateau is more significant than that of daytime warming. ③We also found diverse responses of vegetation type to daytime and night-time warming across the Loess Plateau. We found that the partial correlation between NDVI and Tmax was positive (P<0.05) except grassland and crop. The partial correlation between Tmin and NDVI of crop was negative (P<0.01), and the partial correlation between Tmin and NDVI of other vegetation was positive (P<0.05). Our results provide a demonstration for studying regional responses of vegetation to climate extremes under global climate change.

Key words: Loess Plateau, growing season, maximum temperature, minimum temperature, asymmetric warming, NDVI, vegetation dynamics, day and nighttime warming, global warming