Abstract
The dynamic change and spatial–temporal distribution of vegetation coverage are of great significance for regional ecological evolution, especially in the subtropics and tropics. Identifying the heterogeneity in vegetation activities and its response to climate factors is crucial for projecting ecosystem dynamics. We used long-term (2001–2018) satellite-derived enhanced vegetation index (EVI) datasets and climatic factors to analyze the spatiotemporal patterns of vegetation activities in an experimental area in Guangdong Province (China), as well as their links to changes in temperature (TEM), relative humidity (HUM), precipitation (PRE), sunshine duration (SUN), and surface runoff. The pruned exact linear time change point detection method (PELT) and the disturbance lag model (DLM) were used to understand the detailed ecological coverage status and time lag relationships between the EVI and climatic factors. The results indicate the following. (1) At the whole regional scale, a significant overall upward trend in the EVI variation was observed in 2001–2018. More specifically, there were two distinct periods with different trends, which were split by a turning point in 2005. PRE was the main climate-related driver of the rising EVI pre-2005, and the increase in TEM was the main climate factor influencing the forest EVI variation post-2006. (2) A three-month time lag effect was observed in the EVI response to relative humidity. The same phenomenon was found in the sunshine duration factor. (3) The EVI of farmlands (one type of land use) exhibited the largest lags between relative humidity and the sunshine duration factor, followed by grasslands and forests. (4) The comprehensive index of surface runoff could explain the time lags of vegetation activities, and the surface runoff value showed an apparently negative relationship with the vegetation coverage change.
Highlights
Vegetation plays an essential role in terrestrial ecosystems and is a dominant link between the atmosphere, soil, and biosphere with respect to the transfer of materials and exchange of energy [1]
This study focuses on the vegetation dynamics and the contributions of climate variability, while the Enhanced Vegetation Index (EVI) is selected as a vegetation indicator for detecting vegetation activities
The Pruned Exact Linear Time (PELT) change point detection method was applied to monitor the offline change points in the annual mean EVI time-series at the regional scale, and the two-part piecewise linear regression model determined the changes in the trends within different periods (Figure 3)
Summary
Vegetation plays an essential role in terrestrial ecosystems and is a dominant link between the atmosphere, soil, and biosphere with respect to the transfer of materials and exchange of energy [1]. To understand the mechanisms behind the growth processes of vegetation ecosystems, it is necessary to monitor spatiotemporal changes and quantitatively assess the response of vegetation and associated feedbacks to the Earth’s climate system on regional and global scales. Studies focusing on climate change have aimed to understand the relationship between vegetation growth and climate factors, such as temperature and precipitation, on inter-annual and intra-annual scales [4,5]. Climate extremes, such as drought, can drive vegetation dynamics, and this is true in regions with a widespread karst geomorphology, where the soil is not Remote Sens.
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