NDVI indicated inter-seasonal non-uniform time-lag responses of terrestrial vegetation growth to daily maximum and minimum temperature

摘要

Climate warning exhibits asymmetric patterns over a diel cycle, with the trend of daily minimum temperature (Tmin) exceeds that of daily maximum temperature (Tmax), which is expected to significantly affect terrestrial vegetation growth. To date, many studies have documented the instantaneously asymmetric impacts of Tmax and/ or Tmin on terrestrial ecosystems, but little is known about the non-uniform time-lag effects of Tmax and/or Tmin on vegetation growth. Using monthly datasets of normalized difference vegetation index (NDVI) as the proxy for vegetation vigor and the accumulated Tmax and Tmin on representatives of asymmetric warming, we quantitatively investigated the inter-seasonal non-uniform time-lag effects of Tmax and/or Tmin on terrestrial vegetation growth from 1982 to 2014 by applying partial correlation and time-lag analyses. Our results indicate that both Tmax and Tmin have significant time-lag effects on vegetation growth that exhibit spatial heterogeneities; the same vegetation type exhibits distinguished asymmetric responses to Tmax vs. Tmin; and different vegetation types respond to Tmax and/or Tmin with diverse time-lag effects; the overall average lagged times of Tmax and Tmin on vegetation growth were 1.68 +/- 1.05 months and 1.45 +/- 0.96 months, respectively; terrestrial vegetation growth correlates with Tmax reversely against Tmin over most regions and vegetation types. This study provided new insights into the non-uniform responses of vegetation to asymmetric warming. Moreover, our findings highlight the urgency of the currently used climate-vegetation models to consider the non-uniform time-lag effects found in this study so as to improve their performances in future investigation of vegetation-climate interactions.