Altered trends in carbon uptake in China's terrestrial ecosystems under the enhanced summer monsoon and warming hiatus

Abstract

The carbon budgets in terrestrial ecosystems in China are strongly coupled with climate changes. Over the past decade, China has experienced dramatic climate changes characterized by enhanced summer monsoon and decelerated warming. However, the changes in the trends of terrestrial net ecosystem production (NEP) in China under climate changes are not well documented. Here, we used three ecosystem models to simulate the spatiotemporal variations in China's NEP during 1982–2010 and quantify the contribution of the strengthened summer monsoon and warming hiatus to the NEP variations in four distinct climatic regions of the country. Our results revealed a decadal-scale shift in NEP from a downtrend of –5.95 Tg C/yr2 (reduced sink) during 1982–2000 to an uptrend of 14.22 Tg C/yr2 (enhanced sink) during 2000–10. This shift was essentially induced by the strengthened summer monsoon, which stimulated carbon uptake, and the warming hiatus, which lessened the decrease in the NEP trend. Compared to the contribution of 56.3% by the climate effect, atmospheric CO2 concentration and nitrogen deposition had relatively small contributions (8.6 and 11.3%, respectively) to the shift. In conclusion, within the context of the global-warming hiatus, the strengthening of the summer monsoon is a critical climate factor that enhances carbon uptake in China due to the asymmetric response of photosynthesis and respiration. Our study not only revealed the shift in ecosystem carbon sequestration in China in recent decades, but also provides some insight for understanding ecosystem carbon dynamics in other monsoonal areas.

Interannual variability of terrestrial net ecosystem productivity over China: regional contributions and climate attribution

“…All three models use the same driving data, including climate, land cover, and soil texture. The other three models were performed using historical climate fields from the CRUNCEP v4 dataset (http://dods.extra.cea.fr/data/p529viov/cruncep/), which had strong correlations with those used in the first three models (He et al 2018). A detailed description of these six models (including model input data, model evaluation, and simulation protocol) can be found in He et al (2018) and Piao et al (2015).…”

“…Modeled outputs from four simulation experiments (He et al 2018) were used to quantify the effects of climate, atmospheric CO 2 concentration, and nitrogen deposition on the terrestrial NEP IAV in China. CEVSA2 and BEPS performed three experiments (I, II, and III).…”

“…During the period 1981-2000, the annual total net ecosystem productivity in China ranged from −0.32 to 0.25 Pg C yr −1 with a coefficient of variation of 196%, and net primary productivity contributed more than heterotrophic respiration to this variation in arid northern China but less in moist southern China (Cao et al 2003). The magnitude (Piao et al 2009), trend (Cao et al 2003, He et al 2018 of land C sink in China, and the contributions from multiple global change factors (Tian et al 2011) also have a distinct regional variation. The high rate of variation in Asian monsoon climate strongly influences variation in terrestrial ecosystems in China (Fu and Wen 1999).…”

“…Influenced by the East Asia monsoon, terrestrial ecosystems in four climate zones (i.e. temperate continental, temperate monsoonal, high cold Tibetan Plateau, and subtropical-tropical monsoonal) have experienced various climate changes in both precipitation and temperature (He et al 2018).…”

Terrestrial CO2 Fluxes, Concentrations, Sources and Budget in Northeast China: Observational and Modeling Studies

“…Liu et al (2018) reported that surface CO 2 concentrations simulated with the WRF‐VPRM exhibited a similar trend with those observed at the Shangdianzi station in Beijing from February to May in 2015. In sum, long‐term simulations and observations of CO 2 fluxes/concentrations required to investigate and quantify CO 2 sources/sinks and budget in China are currently rarely reported (He et al, 2019; Thompson et al, 2016; Zhang et al, 2014).…”