Interannual Variations in Terrestrial Net Ecosystem Productivity and Climate Attribution in the Southern Hilly Region of China

Abstract

The vegetation ecosystem in the southern hilly region of China (SHRC) plays a crucial role in the country’s carbon reservoir. Clarifying the dynamics of net primary productivity (NPP) in this area and its response to climate factors in the context of climate change is important for national forest ecology, management, and carbon neutrality efforts. This study, based on remote sensing and meteorological data spanning the period 2001 to 2021, aims to unveil the spatiotemporal patterns of vegetation productivity and climate factors in the southern hilly region, explore interannual variation characteristics of vegetation productivity with altitude, and investigate the response characteristics of NPP to various climate factors. The results indicate that from 2001 to 2021, the annual average NPP in the southern hilly region had a significant increasing trend of 2.13 ± 0.78 g m−2 a−1. The trend of NPP varies significantly with altitude. Despite a general substantial upward trend in vegetation NPP, regions at lower elevations exhibit a faster rate of increase, suggesting a diminishing difference in the NPP of different elevation ranges. The overall rise in average temperature has positive implications for the southern hilly region, while the impact of precipitation on vegetation NPP demonstrates noticeable spatial heterogeneity. Regions in which vegetation NPP is significantly negatively correlated with precipitation are mainly concentrated in the southern areas of Guangdong, Fujian, and Jiangxi provinces. In contrast, other regions further away from the southeastern coast tend to exhibit a positive correlation. Over the past two decades, there has been an asymmetry in the diurnal temperature variation in the SHRC, with the nighttime warming rate being 1.8 times that of the daytime warming rate. The positive impact of daytime warming on NPP of vegetation is more pronounced than the impact of nighttime temperature changes. Understanding the spatiotemporal patterns of NPP in the SHRC and the characteristics of its response to climate factors contributes to enhancing our ability to protect and manage vegetation resources amidst the challenges of global climate change.

Assessing the Distribution and Driving Effects of Net Primary Productivity along an Elevation Gradient in Subtropical Regions of China

“…In coastal areas where ANPP has declined, human activities have been the primary factor driving the reduction, with their negative impact being more significant than that of climate change, aligning with the findings of previous research [76,87,88]. This is likely due to the rapid urbanization in these regions.…”

“…Evergreen broadleaf forests are mainly distributed in the southeastern coastal regions of the study area and in southern Yunnan Province. In these areas, rapid urbanization has been a primary factor contributing to the decline in ANPP [76].…”

“…Although previous research indicates [87] that in highly urbanized areas, low productivity vegetation is gradually replaced by higher productivity types, the increase in ANPP due to this vegetation transformation was insufficient to offset the decline caused by the expansion of impervious urban surfaces. Moreover, according to a study by Xin et al, the adverse effects of nocturnal warming on vegetation growth in the Fujian and Guangdong regions also contributed to the decline in ANPP [76]. Therefore, in these regions, human activities predominantly contribute to the reduction in ANPP.…”

“…Temperature and precipitation have always been the two most commonly used factors in studying the driving models between ANPP and meteorological elements [49,64,76,[96][97][98][99], as they largely affect the growth and distribution of vegetation. However, previous studies have not reached consistent conclusions regarding the impact of these two meteorological factors on ANPP.…”

“…We observed a trend of temperature increase in the middle and upper areas of Yunnan Province and the central high-elevation areas of Taiwan Province, implying that in these areas, the rise in temperature has a negative effect on ANPP, leading to a decrease in ANPP. This might be because global warming increases the evapotranspiration of the ecosystem, which intensifies soil water shortage, restricting vegetation growth and reducing ANPP [76,99]. Another part of the reason could be that in high altitude areas, global warming causes snow and ice to melt, increasing soil moisture at plant root zones, causing plants to be in an anaerobic state, which in turn leads to a decrease in ANPP [101].…”