Time lag of vegetation growth on the Loess Plateau in response to climate factors: Estimation, distribution, and influence

Vegetation growth is importantly affected by seasonal weather patterns. The time lag between changes in these patterns and the vegetative response is an important factor in vegetation-climate interactions and can vary considerably with the spatial heterogeneity of an ecosystem. In this study of the Loess Plateau, China, highly accurate time lags were determined at the daily scale using linear regression based on a multiyear normalized difference vegetation index (NDVI) dataset (1982-2015) and the corresponding reconstructed monthly climate series. We found that lag length varied among catchments, vegetation zones, and land-cover types. The mean time lag between precipitation and the NDVI response varied from 7.9 days to 17.7 days across the catchments; for temperature and NDVI, the lag in response ranged from 6.2 days to 253 days. Across the six vegetation zones that range from the southeast to the northwest of the Loess Plateau, both the precipitation-NDVI and temperature-NDVI lag lengths were largest in the central zones and lower in the zones closer to the edges of the plateau. Among the different land-cover types, grassland had the largest lags between precipitation or temperature change and the NDVI response, followed by shrubland, arable land, and then forests. The possible impact of vegetative time lags on sediment yield was also investigated for the first time, and this information has great relevance for soil conservation on the Loess Plateau and sediment reduction in the lower Yellow River. (C) 2020 Elsevier B.V. All rights reserved.