Abstract
Abstract. Climate change, rising CO2 concentration, and land use and land cover change (LULCC) are primary driving forces for terrestrial gross primary productivity (GPP), but their impacts on the temporal changes in GPP are uncertain. In this study, the effects of the three main factors on the interannual variation (IAV) and seasonal cycle amplitude (SCA) of GPP in China were investigated using 12 terrestrial biosphere models from the Multi-scale Synthesis and Terrestrial Model Intercomparison Project. The simulated ensemble mean value of China's GPP between 1981 and 2010, driven by common climate forcing, LULCC and CO2 data, was found to be 7.4±1.8 Pg C yr−1. In general, climate was the dominant control factor of the annual trends, IAV and seasonality of China's GPP. The overall rising CO2 led to enhanced plant photosynthesis, thus increasing annual mean and IAV of China's total GPP, especially in northeastern and southern China, where vegetation is dense. LULCC decreased the IAV of China's total GPP by ∼7 %, whereas rising CO2 induced an increase of 8 %. Compared to climate change and elevated CO2, LULCC showed less contributions to GPP's temporal variation, and its impact acted locally, mainly in southwestern China. Furthermore, this study also examined subregional contributions to the temporal changes in China's total GPP. Southern and southeastern China showed higher contributions to China's annual GPP, whereas southwestern and central parts of China explained larger fractions of the IAV in China's GPP.
Highlights
Terrestrial ecosystems can function as a major sink in the global carbon cycle, potentially offsetting a significant amount of anthropogenic carbon emissions (Le Quéré et al, 2018)
Three sensitivity model simulations were used in this study: SG1, driven by time-varying climate data; SG2, considering the effect of land use and land cover change (LULCC) based on SG1; and SG3, similar to SG2, but using time-varying atmospheric CO2 concentration
These three experiments can be used to assess the relative contributions of climate change, LULCC and rising CO2 concentration to temporal changes in gross primary productivity (GPP)
Summary
Terrestrial ecosystems can function as a major sink in the global carbon cycle, potentially offsetting a significant amount of anthropogenic carbon emissions (Le Quéré et al, 2018). Gross primary productivity (GPP) is the major driver of terrestrial ecosystem carbon storage and plays a key role in terrestrial carbon cycle (Yuan et al, 2010; Mao et al, 2012; Piao et al, 2013; Anav et al, 2015; Zhou et al, 2016; Ito et al, 2017). Simulations from a coupled earth system indicated that CO2 fertilization increased the global net primary productivity by ∼ 2.3 Pg C yr−1 between 1850 and 2005 (Devaraju et al, 2016) It suggests that the CO2 effect on land carbon storage may be a key potential negative feedback to future climate (Schimel et al, 2014). The extent to which CO2 fertilization is responsible for current and future terrestrial carbon storage is still unclear (Zaehle et al, 2010; IPCC, 2013)
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