The strongest EI Nino event stimulated ecosystem respiration, not evapotranspiration, over a humid alpine meadow on the Qinghai-Tibetan Plateau

NWIPB OpenIR

	The strongest EI Nino event stimulated ecosystem respiration, not evapotranspiration, over a humid alpine meadow on the Qinghai-Tibetan Plateau
	Li, Hongqin; Zhang, Fawei; Wang, Wenying; Li, Yikang; Lin, Li; Wang, Junbang; Guo, Xiaowei; Cao, Guangmin; Yang, Yongsheng; Li, Yingnian
	2018
发表期刊	ECOLOGICAL INDICATORS
卷号	91
摘要	Frequent EI Nino events have worldwide impacts, but their effects on carbon and water budgets in alpine grasslands have been poorly explored. The responses of carbon and water vapor exchanges, monitored by the eddy covariance techniques, to the strongest EI Nino event in 2015/2016 were investigated over a humid alpine meadow on the Northeastern Qinghai-Tibetan Plateau. Monthly air temperature (T-a) in August could be considered as a clear indicator of this event and was elevated by 44% (by 4.0 degrees C) in 2016, mainly due to a 204% (5.2 degrees C) increase in daily minimum To. On a diurnal scale, a paired-samples T-test between the El Nino duration (August in 2016) and the reference period (August in 2014 and 2015) revealed that the El Nino-induced increase in gross primary production (GPP, 0.078 gCm(-2).h(-1)) was lower than the growth in ecosystem respiration (RES, 0.12 gC.m(-2).h(-1)), resulting in an increase in net ecosystem CO2 exchange (NEE, 0.079 gC.m(-2).h(-1)). Diurnal evapotranspiration (ET) was significantly increased, by 8.6%, at a rate of 0.011 mm.h(-1). On a monthly scale, this ecosystem fixed less carbon by 58.7 g C.m(-2).month(-1) while ET water losses increased by only 6.2 mm.month(-1) in August. The alpine meadow thus acted as a carbon sink with a 36.2 g C.m(-2).year(-1) influx in 2015, but switched to a carbon source with a 21.6 g C.m(-2)year(-1) efflux in 2016, mainly due to a 78.7 g C.m(-2).year(-1) increase in RES. Annual ET increased by less 3%. The divergent responses of CO2 and H2O fluxes were mostly attributed to a great increase only in nocturnal To, which instantaneously stimulated RES but not ET. Our findings revealed that extreme nocturnal warming led to greater carbon losses and weaker compensatory carbon gains, highlighting the inconsistent response of carbon dynamics to gradual warming and to exceptional warmth in humid alpine meadows.
关键词	Gross primary production Ecosystem respiration Evapotranspiration Eddy covariance technique Extreme events Alpine meadow
文献类型	期刊论文
条目标识符	http://210.75.249.4/handle/363003/59997
专题	中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	Li, Hongqin,Zhang, Fawei,Wang, Wenying,et al. The strongest EI Nino event stimulated ecosystem respiration, not evapotranspiration, over a humid alpine meadow on the Qinghai-Tibetan Plateau[J]. ECOLOGICAL INDICATORS,2018,91.
APA	Li, Hongqin.,Zhang, Fawei.,Wang, Wenying.,Li, Yikang.,Lin, Li.,...&Li, Yingnian.(2018).The strongest EI Nino event stimulated ecosystem respiration, not evapotranspiration, over a humid alpine meadow on the Qinghai-Tibetan Plateau.ECOLOGICAL INDICATORS,91.
MLA	Li, Hongqin,et al."The strongest EI Nino event stimulated ecosystem respiration, not evapotranspiration, over a humid alpine meadow on the Qinghai-Tibetan Plateau".ECOLOGICAL INDICATORS 91(2018).