X. J. Liu

China Agricultural University

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K. H. Li

Chinese Academy of Sciences

Peter Christie

Institute of Soil Science

Wei Song

Guangzhou Institute of Geochemistry

Fusuo Zhang

China Agricultural University

Y. Y. Liu

Chinese Academy of Sciences

Xiao‐Tao Lü

Institute of Applied Ecology

Anwar Mohammat

Chinese Academy of Sciences

Jianlin Shen

Lanzhou University

Yaping Chang

Northwest Institute of Eco-Environment and Resources

F. Fang

Institute of Modern Physics

Cooperative Institutions

Chinese Academy of Sciences

University of Chinese Academy of Sciences

China Agricultural University

Ministry of Agriculture and Rural Affairs

Xinjiang Institute of Ecology and Geography

Northwest A&F University

Lanzhou University

United States Department of Agriculture

Tsinghua University

Shanxi Agricultural University

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Response of carbon dioxide emissions to sheep grazing and N application in an alpine grassland – Part 1: Effect of sheep grazing

Biogeosciences (2014)

Yanming Gong Anwar Mohammat X. J. Liu K. H. Li Peter Christie

Abstract. Previous work has failed to address fully the response of (autotrophic and heterotrophic) respiration to grazing in different ecosystems, particularly in alpine grasslands outside the growing season. From 2010 to 2011 a field experiment combined two methods (static closed chambers and a closed dynamic soil CO2 flux system) in alpine grasslands located in the Tianshan Mountains. We examined the effects of grazing regime on ecosystem respiration (Re) both outside (NGS) and during (GS) the growing season and determined the pattern of Re in relation to climate change. There was no significant change in CO2 emissions under grazing. Heterotrophic respiration (Rh) accounted for 78.5% of Re with short-term grazing exclusion and 93.2% of Re with long-term grazing exclusion. Re, Rh and autotrophic respiration (Ra) fluxes outside the growing season were equivalent to 12.9%, 14.1% and 11.4% of the respective CO2 fluxes during the growing season. In addition, our results indicate that soil water content played a critical role in Ra in the cold and arid environment. Both Rh and Re were sensitive to soil temperature. Moreover, our results suggest that grazing exerted no significant effect on CO2 emissions in these alpine grasslands.

Ecosystem respiration

Soil respiration

Growing season

Grazing pressure

10.5194/bg-11-1743-2014

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Citations (14)

Response of carbon dioxide emissions to sheep grazing and N application in an alpine grassland – Part 2: Effect of N application

Biogeosciences (2014)

Yanming Gong Anwar Mohammat X. J. Liu K. H. Li Peter Christie

Abstract. Widespread nitrogen (N) enrichment resulting from anthropogenic activities has led to great changes in carbon exchange between the terrestrial biosphere and the atmosphere. Grassland is one of the most sensitive ecosystems to N deposition. However, the effect of N deposition on ecosystem respiration (Re) in grasslands has been conducted mainly in temperate grasslands, which are limited largely by water availability, with few studies focused on alpine grasslands that are primarily constrained by low temperatures. Failure to assess the magnitude of the response in Re outside the growing season (NGS) in previous studies also limits our understanding of carbon exchange under N deposition conditions. To address these knowledge gaps we used a combination of static closed chambers and gas chromatography in an alpine grassland from 2010 to 2011 to test the effects of N application on ecosystem respiration (Re) both inside and outside the growing season. There was no significant change in CO2 emissions under N application. Re outside the growing season was at least equivalent to 9.4% of the CO2 fluxes during the growing season (GS). Annual Re was calculated to be 279.0–403.9 g CO2 m−2 yr−1 in Bayinbuluk alpine grasslands. In addition, our results indicate that soil temperature was the dominant abiotic factor regulating variation in Re in the cold and arid environment. Our results suggest that short-term N additions exert no significant effect on CO2 emissions in alpine grassland.

Growing season

Ecosystem respiration

Soil respiration

Deposition

Terrestrial ecosystem

Grassland ecosystem

10.5194/bg-11-1751-2014

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Atmospheric reactive nitrogen concentrations at ten sites with contrasting land use in an arid region of central Asia

Biogeosciences (2012)

K. H. Li Wei Song X. J. Liu Jianlin Shen Xiaojin Luo

Abstract. Atmospheric concentrations of reactive nitrogen (Nr) species from 2009 to 2011 are reported for ten sites in Xinjiang, China, an arid region of central Asia. Concentrations of NH3, NO2, particulate ammonium and nitrate (pNH4+ and pNO3−) showed large spatial and seasonal variation and averaged 7.71, 9.68, 1.81 and 1.13 μg N m−3, and PM10 concentrations averaged 249.2 μg m−3 across all sites. Lower NH3 concentrations and higher NO2, pNH4+ and pNO3− concentrations were found in winter, reflecting serious air pollution due to domestic heating in winter and other anthropogenic sources such as increased emissions from motor traffic and industry. The increasing order of total concentrations of Nr species was alpine grassland; desert, desert-oasis ecotone; desert in an oasis; farmland; suburban and urban ecosystems. Lower ratios of secondary particles (NH4+ and NO3−) were found in the desert and desert-oasis ecotone, while urban and suburban areas had higher ratios, which implied that anthropogenic activities have greatly influenced local air quality and must be controlled.

Ecotone

Reactive nitrogen

10.5194/bg-9-4013-2012

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Citations (21)

Tillage and Nitrogen Application Effects on Nitrous and Nitric Oxide Emissions from Irrigated Corn Fields

Plant and Soil (2005)

X. J. Liu A. R. Mosier Ardell D. Halvorson Fusuo Zhang

Growing season

Cropping system

Nitrous oxide

Conventional tillage

10.1007/s11104-005-4894-4

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Citations (94)

Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China

Atmospheric chemistry and physics (2015)

Wen Xu Xiaojin Luo Yuepeng Pan Lin Zhang Aohan Tang

Abstract. A Nationwide Nitrogen Deposition Monitoring Network (NNDMN) containing 43 monitoring sites was established in China to measure gaseous NH3, NO2, and HNO3 and particulate NH4+ and NO3− in air and/or precipitation from 2010 to 2014. Wet/bulk deposition fluxes of Nr species were collected by precipitation gauge method and measured by continuous-flow analyzer; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet/bulk Nr deposition. On a national basis, the annual average concentrations (1.3–47.0 μg N m−3) and dry plus wet/bulk deposition fluxes (2.9–83.3 kg N ha−1 yr−1) of inorganic Nr species are ranked by land use as urban > rural > background sites and by regions as north China > southeast China > southwest China > northeast China > northwest China > Tibetan Plateau, reflecting the impact of anthropogenic Nr emission. Average dry and wet/bulk N deposition fluxes were 20.6 ± 11.2 (mean ± standard deviation) and 19.3 ± 9.2 kg N ha−1 yr−1 across China, with reduced N deposition dominating both dry and wet/bulk deposition. Our results suggest atmospheric dry N deposition is equally important to wet/bulk N deposition at the national scale. Therefore, both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.

Deposition

10.5194/acp-15-12345-2015

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Citations (393)