Abstract
Knowledge of vegetation dynamics in relation to climatic changes and human activities is essential for addressing the terrestrial carbon cycle in the context of global warming. Scientific detection and quantitative attribution of vegetation dynamic changes in different climatic zones and human activities are the focus and challenge of the relevant research. Taking the Poyang Lake basin as the research area, this study aimed to reveal how climate and land use drive changes in net primary productivity (NPP) in the subtropical humid basin. Change patterns of vegetation NPP and their relationships with meteorological factors across the basin were first investigated based on the estimation of 18 year (2000–2017 year) NPP by using a typical light energy utilization model, the Carnegie-Ames-Stanford Approach (CASA) model. Quantitative analysis was then conducted to explicitly distinguish the driving effects of climate change and land-use change on NPP dynamics in two different periods. Results show that annual NPP and total production (TP) of the Poyang Lake basin increased significantly from 2000 to 2017. During this period, land-use change in the basin was driven by the process of urbanization expansion and the efforts of ecological protection. Climatically, the temperature is the major influencing climatic factor in determining vegetation productivity in the subtropical humid basin, followed by precipitation and solar radiation. In addition, our investigation also revealed that with comparison to the period of 2000s, the increased TP of the Poyang Lake basin due to climate change in 2010s was much bigger than the decreased TP due to land-use change. However, in the areas where the land-use change occurred, the decreased TP was mainly attributed to the impact of land-use change, even though climate change showed a positive effect of increasing productivity.
Highlights
The terrestrial ecosystem, which links the land and atmosphere, can well reflect and elaborate the energy exchange, carbon cycle, and the effect of human activities on the earth’s surface [1,2,3]
Taking the Poyang Lake basin as the study area, the current study investigated the change patterns and causes of vegetation net primary productivity (NPP) in a subtropical humid area
In terms of climatic influencing factors, the NPP of the Poyang Lake basin was positively correlated with temperature, precipitation, and solar radiation at the basin scale
Summary
The terrestrial ecosystem, which links the land and atmosphere, can well reflect and elaborate the energy exchange, carbon cycle, and the effect of human activities on the earth’s surface [1,2,3]. The net primary productivity (NPP) of the terrestrial ecosystem refers to the remaining fraction of absorbed carbon by vegetation through photosynthesis in unit time after the carbon loss of plant respiration. It is a fundamental indicator of ecosystem health and productivity, which is of great significance in determining the carbon source/sink function of the ecosystem and regulating the ecological process [4]. As a key link of the biogeochemical carbon cycle, the spatial and temporal variations of NPP are determined by the complex interactions among vegetation, soil, and atmosphere, and strongly influenced by human activities and global environmental changes [8,9,10]. Research on the dynamics of the terrestrial ecosystem represented by NPP has received increasing attention from the scientific community [11,12,13]
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