Changes in Forest Net Primary Productivity in the Yangtze River Basin and Its Relationship with Climate Change and Human Activities

Abstract

Net Primary Productivity (NPP) is a basis of material and energy flows in terrestrial ecosystems, and it is also an important component in the research on carbon cycle and carbon budget. This paper evaluated the spatial distribution pattern and temporal change trends for forest NPP simulated by the LPJ (Lund-Potsdam-Jena) model and NDVI (normalized difference vegetation index) in the Yangtze River basin from 1982 to 2013. The results revealed that: (1) the spatial distribution of the forest NPP and NDVI in the Yangtze River basin has gradually decreased from the southeast coast to the northwest. The forest NPP and NDVI in the mid-lower Yangtze were higher than that of the upper Yangtze; (2) the forest NPP and NDVI in most areas of the Yangtze River basin were positively correlated with the temperature and precipitation. Moreover, the correlations among the temperature with the forest NPP and NDVI were stronger than that of correlations among precipitation with forest NPP and NDVI. Moreover, the extreme drought event in the year of 2004–2005 led the NPP to decrease in the middle and lower Yangtze River basin; (3) human activity such as major ecological projects would have a certain impact on the NPP and NDVI. The increase in forest areas from 2000 to 2010 was larger than that from 1990 to 2000. Moreover, the increasing rate for the NDVI was higher than that of NPP, especially after the year 2000, which indicates that the major ecological projects might have great impacts on the vegetation dynamics. Moreover, more attention should be paid on the joint impacts of human activity and climate change on terrestrial NPP and NDVI.

Quantifying Influences of Natural and Anthropogenic Factors on Vegetation Changes Based on Geodetector: A Case Study in the Poyang Lake Basin, China

“…For instance, Gu et al [36] investigated the response of vegetation change to climate change in the Red River basin during 2000-2014 based on the partial correlation and regression analysis. Zhang, et al [37] applied correlation and regression analysis to study vegetation change and its relationship with climate and human factors in the Yangtze River basin from 1982 to 2013. In recent years, quantifying the contributions of climate change and human activities to vegetation change has become a crucial topic of global change.…”

The Dominant Driving Force of Forest Change in the Yangtze River Basin, China: Climate Variation or Anthropogenic Activities?

“…It is an important indicator to monitor the status of vegetation growth. The methods of estimating NPP can be mainly divided into three categories: field measurement, model simulation, and remote sensing estimations [25]. Compared with the other two kinds of methods, the remote sensing estimation method is more suitable for large-scale vegetation research due to its high efficiency and low cost [25].…”

“…The methods of estimating NPP can be mainly divided into three categories: field measurement, model simulation, and remote sensing estimations [25]. Compared with the other two kinds of methods, the remote sensing estimation method is more suitable for large-scale vegetation research due to its high efficiency and low cost [25]. Thanks to the rapid development of remote sensing technology, high-resolution remote sensing satellite products have been widely used in vegetation dynamics research on large scales in recent years [26][27][28][29].…”

“…The assessment of the previous round of GTGP could provide a reference for the next round. Although some studies have analyzed vegetation change in recent years [25,39,40], there are few studies to quantify the relative contribution of climate variations and anthropogenic activities (especially ecological restoration programs) to the forest ecosystem in YRB. Therefore, we selected NPP as an indicator of forest status to explore the driving mechanism of forest variation.…”

Net Primary Productivity of a Mountain Forest Ecosystem as Affected by Climate and Topography

“…The forest vulnerability to climate change is mainly adjudged by changes in the phonological characteristics, tree line shifts, distribution of forest types and productivity (Kumar et al, 2018 and references therein). The NPP has been used to evaluate response of forest ecosystem to climate in many studies (e.g., Yong et al, 2007;Gao et al, 2013;Zhang et al, 2014;Fang et al, 2013;Erşahin et al, 2016;Liu et al, 2018;Gang et al, 2019;Zhang et al, 2019). Zhou et al (2018) reported a substantial decrease in forest NPP in southeastern China in 2009-2010 droughts (from August 2009 to April 2010).…”