Responses of subalpine meadow to climatic factors and the time lag effects in Wuyi Mountains from 2000 to 2019

Abstract

Subalpine meadow is extremely sensitive to climate change. Few studies, however, focused on the responses of subalpine meadow to climatic factors in subtropical regions. It is still a challenge to extract the biophysical parameters from optical remote sensing imagery during the growing season. Based on the normalized difference vegetation index (NDVI) time series dataset from the MOD13Q1 vegetation index products and meteorological data, we analyzed the changes of vegetation growth of subalpine meadow at Huanggang Mountain in the top of Wuyishan National Park from 2000 to 2019, its responses to climate factors and the time lag effects. The results showed that NDVI in summer increased insignificantly during 2000-2019, and that NDVI in the growing season, spring, and autumn increased significantly. The enhancement of NDVI was mainly contributed by the increasing temperature (0.026 ℃·a-1) from 2000 to 2019. The increasing temperature in spring and autumn influenced meadow growth more than that in summer and growing season. NDVI of the growing season in subalpine meadow was sensitive to precipitation,indicating that the growth of subalpine meadow was strongly affected by precipitation even in the subtropical region with sufficient precipitation. Temperature and precipitation in different growth periods had different time lag effects on the NDVI of subalpine meadowo. The time lag effects of temperature on subalpine meadow were 0-1 month, and that of precipitation were 2-3 month.