Changes in Vegetation Greenness and Their Influencing Factors in Southern China

Abstract

Since the 21st century, China has experienced rapid development, and the spatial and temporal changes in vegetation cover have become increasingly significant. Southern China is a representative region for human activities, climate change, and vegetation change, but the current human understanding of the interactions between vegetation and its influencing factors is still very limited. In our study, we use NDVI as the vegetation greenness data, land cover data, temperature, precipitation, downgradient shortwave radiation, and CO2 data to investigate the interrelationship among vegetation, climate change, and human activities in southern China. The changes and their consistency were studied by trend analysis and Hurst exponent analysis. Then, the contribution of each influencing factor from 2001 to 2020 was quantified by random forest. The results showed that the vegetation in southern China showed an overall rising trend, and areas with a continuous changing trend were concentrated in the Pearl River Delta, western Guangdong, and eastern Guangdong, with a growth rate of 0.02∼0.04%. The vegetation in northern Guangdong did not change significantly. The main factor of NDVI spatial variation in southern China is the land-use factor, accounting for 79.4% of the variation, while climate factors produce further differences. The contributions and lagged effects of NDVI factors on different land-use types and the lagged effects of different climate factors are different and are related to the climate and vegetation background in Sourthern China. Our study is useful in estimating the contribution of NDVI change by each considered factor and formulating environmentally friendly regional development strategies and promoting human–land harmony.

Climatic and Anthropogenic Contributions to Vegetation Changes in Guangdong Province of South China

“…This study found that vegetation growth in most areas of Guangdong Province displayed an increasing trend during 2001-2020, and the decreasing trend was mainly concentrated in the urban areas and peripheries in the PRD and eastern East MD ecoregions (Figure 3), in agreement with previous studies [9,33]. However, these studies demonstrated a non-significant increasing or even decreasing trend of vegetation greenness in most area of northern Guangdong [9,33], contrasting with our results that vegetation improved significantly in the NG eco-region. This is partially due to the more extended study The contribution type of climate change and human activities to vegetation dynamics was classified under various scenarios (Table 2, Figure 8).…”

“…Since both climate variations and human activities have tremendous impacts on vegetation in Guangdong Province [14,33,45], residual trend analysis was used to distinguish the relative impacts of climate change and human activities on vegetation changes [38]. This method assumes that the unexplained variation in the model between vegetation and climatic variables is attributed to anthropogenic activities [60].…”

“…A large number of studies have made remarkable progress on this task and at least two kinds of approaches are proposed and widely used so far. First, statistical techniques and models such as the multiple linear regression model [30], ridge regression [31], structural equation modeling [32], random forest algorithms [33], redundancy analysis [34], geographically weighted regression models [35], and geographical detectors [36,37] are often used to explore the relationship between vegetation indices and their climatic and anthropogenic drivers to quantity the relative role of their influences. These models need both climatic and human-related variables as input data, but the indicators of human activities are usually difficult to obtain and often inconsistent with the spatial resolution of climatic indicators.…”

“…During the past decades, Guangdong Province has experienced a soaring economy and population boom, and land use has changed dramatically, thereby affecting ecosystem services and habitat quality [46,47]. Current studies indicate that the vegetation in Guangdong Province changed significantly during the urbanization process [33]. As such, Guangdong Province is a typical area for studying the combined effects of climate change and human disturbance on vegetation.…”

“…As such, Guangdong Province is a typical area for studying the combined effects of climate change and human disturbance on vegetation. By taking land use/cover change (LUCC) to represent human activities, previous studies emphasized human activities as the main driving force of vegetation changes and explored how the interaction of climate variations and human activities affected vegetation dynamics in Guangdong Province [9,33]. LUCC is one of the most direct manifestations of human activities, but it cannot reflect all aspects of human activities.…”