Regime shift of the hydroclimate–vegetation system in the Yellow River Delta of China from 1982 through 2015

Abstract

The Yellow River Delta (YRD) has been experiencing substantial climatic, hydrological, and anthropogenic stresses, and a sound understanding of the regime shift in its hydroclimate-vegetation system is of fundamental importance for maintaining the health and stability of its regional ecosystems. This study constructs and analyzes a 34-year-dataset (1982-2015) of hydro-climatic variables and satellite-based Normalized Difference Vegetation Index (NDVI) in the YRD. A seasonaltrend decomposition technique based on loess (STL), and a structural change analysis were coupled to detect regime shifts of regional hydroclimate and vegetation in the YRD from 1982 through to 2015. During this period the YRD exhibited a significant warmer-drier-greening trend and experienced four regime shifts of its hydroclimate-vegetation system, with the four shift periods roughly centered in 1989, 1998, 2004, and 2012. Partial correlation analysis revealed that temperature was the dominant factor promoting vegetative growth in spring and autumn (all P NDVI-TEM greater than 0.65), and streamflow impacted the NDVI mainly in summer. Temperature and precipitation were the dominant controls of vegetative growth during the growing season prior to 2002, and thereafter precipitation and streamflow alternately became the main moisture-influencing factors of vegetative growth. Streamflow played an important complementary role on vegetative growth, particularly in near riverine areas when drought exceeds a certain threshold. Additionally, climate shifts determined the changing trend of NDVI across the region, while the effect of land use change is localized and predominant in the northeastern part of the study region. These findings offer an insight into appropriate water regulation of the Yellow River and on climatic adaptation within the YRD.

Spatiotemporal Variation in Driving Factors of Vegetation Dynamics in the Yellow River Delta Estuarine Wetlands from 2000 to 2020

“…(c) indicates the newly added areas of each land use type. Furthermore, climate change played a significant role in the vegetation variations observed in the YRD.Previous research has indicated that temperature is a key driving factor for spring and autumn vegetation growth, while precipitation is an important hydrological factor affecting vegetation growth, besides the impact of runoff[7]. This study demonstrates the enormous potential of multisource remote sensing data fusion methods for the monitoring of vegetation changes in estuarine wetlands.…”

“…Vegetation is the fundamental basis of ecosystem services and functions, and its dynamics act as a sensitive indicator of ecosystem conditions, being closely related to climate change, hydrological conditions, and human activities [7]. In recent years, the rapid development of remote sensing technology has led to it becoming the primary approach used to study wetland evolution processes and patterns.…”

“…As the green ecological corridor of the lower reaches of the Yellow River, the Yellow River Delta has garnered considerable attention. Recently, numerous studies have been conducted to explore the dynamics of wetlands and driving factors of wetland change in the YRD [7,[32][33][34][35]. Climate features play dominant roles in influencing the seasonal variations in vegetation cover [36], temperature predominantly governs vegetation growth during the spring and autumn seasons in the YRD, and runoff plays a crucial supplementary role in plant growth, especially in regions near rivers in which drought surpasses a certain threshold [7].…”

“…Recently, numerous studies have been conducted to explore the dynamics of wetlands and driving factors of wetland change in the YRD [7,[32][33][34][35]. Climate features play dominant roles in influencing the seasonal variations in vegetation cover [36], temperature predominantly governs vegetation growth during the spring and autumn seasons in the YRD, and runoff plays a crucial supplementary role in plant growth, especially in regions near rivers in which drought surpasses a certain threshold [7]. Meanwhile, under the influence of human activities, the wetland area has undergone a sequence of reduction, followed by expansion [37,38].…”