Using the DNDC model to simulate the potential of carbon budget in the meadow and desert steppes in Inner Mongolia, China
In this study, a process-based denitrification-decomposition (DNDC) model was parameterized and validated with CO2 fluxes data measured using eddy covariance (EC) technique in the meadow and desert steppes of Inner Mongolia grasslands, China. The validated model was applied to predict the influence of moderate climate change on carbon (C) budget of the two steppes over the next 30 years.
Materials and methods
A series of parameters associated with plant growth including maximum biomass production, C/N ratio of plant tissue, and accumulating thermal degree days based on local observations were adjusted to meet the requirements of adapting DNDC for the two targeted steppes. Daily weather data for the studied year together with soil properties for the study sites were employed as inputs to simulate the grass growth and soil C dynamics. A baseline and five alternative climate scenarios were utilized to estimate the effect of climate change on the ecosystem C dynamics for the next 30 years. The coefficient of determination (R 2), root mean square error (RMSE), relative mean deviation (RMD), and modeling efficiency (EF) were used to assess the DNDC model based on the EC measurements.
Results and discussion
The DNDC model successfully captured the maximum and minimum soil surface temperature and the effects of rainfall pulse on soil water content (SWC). Validation of ecosystem daily CO2 fluxes against the EC observed values resulted in satisfactory results in both of the meadow and the desert steppe. Additionally, the comparison of monthly simulated results is better than that of daily results. Between 2011 and 2040, if local climate becomes wetter, both steppes would become C sinks, leading to a great net primary productivity (NPP) of 821 and 828 kg C ha−1 year−1 sequestered in soil organic C (SOC), respectively. If local climate becomes drier, they would become C-sources, having the lowest NPP with 166 and 121 kg C ha−1 year−1 lost from the soil C pool, respectively.
The validated DNDC model can be used to predict C dynamics in two semiarid grassland ecosystems. For the upcoming 30 years, if the local climate became wetter, the meadow and desert steppes would act as C sink, absorbing CO2 from the atmosphere and increase the C sequestration potential. However, both steppes would act as C source, releasing CO2 to the atmosphere, and decrease the C sequestration when the local climate becomes drier.
KeywordsCarbon budget Climate change DNDC model Eddy covariance technique Inner Mongolian grassland
Financial support was provided by the Strategic Priority Research Program of the Chinese Academy of Sciences, Grant No. XDB15010200, the National Key Research and Development Program of China (Grant No. 2016YFC0501801), and the Chinese Academy of Sciences (Grant No. KJRH2015-010).
- Bell JE, Sherry R, Luo YQ (2010) Changes in soil water dynamics due to variation in precipitation and temperature: an ecohydrological analysis in a tallgrass prairie. Water Resour Res 46. doi: 10.1029/2009WR007908
- Butterbach-Bahl K, Stange F, Papen H, Grell G, Li CS (2000) Impact of changes in temperature and precipitation on N2O and NO emissions from forest soils. Springer Netherlands, pp 165–171. doi: 10.1007/978-94-015-9343-4_22
- Cai ZC, Sawamoto T, Li CS, Kang GD, Boojawat J, Mosier A, Wassmann R, Tsuruta H (2003), Field validation of the DNDC model for greenhouse gas emissions in East Asian cropping systems. Glob Biogeochem Cycles 17:18–1-10Google Scholar
- IPCC (2013) Annex I: atlas of global and regional climate projections supplementary material RCP4.5Google Scholar
- Kang XM (2011) Modeling carbon budget in a Leymus chinensis steppe ecosystem in Inner Mongolia. Graduate University of Chinese Academy of SciencesGoogle Scholar
- Li CS, Cui JB, Ge S et al (2004) Modeling Impacts of Management on Carbon Sequestration and Trace Gas Emissions in Forested Wetland Ecosystems, Environmental Management 33: S176–S186Google Scholar
- Meng XH, Li XL, Xin XP, Zhou RZ (2009) Study on community characteristics and diversity under different grazing intensity on Leymus chinensis (Trin.) Tzvel. Meadow steppe of Hulunbeier. Acta A Grestia Sinica 17:239–244Google Scholar
- Qiu JJ, Wang LG, Tan HJ, Li H, Li CS (2005) Studies on the situation of soil organic carbon storage in croplands in northeast of China. Agr Sci China 4:101–105Google Scholar
- Wurenqigege (2009) Studies of the characteristic of vegetation and soil and indication under the different degeneration degree in the meadow steppeGoogle Scholar
- Xiao JF, Sun G, Chen JQ et al (2013) Carbon fluxes, evapotranspiration,and water use efficiency of terrestrial ecosystems in China. Agr Forest Meteorol 182–183:76–90Google Scholar
- Xu LK, Baldocchi DD (2003) Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California. Agric For Meteorol 3227:1–18Google Scholar
- Xu R, Wang YS, Zheng XH et al. (2003) A comparison between measured and modeled N2O emissions from Inner Mongolian semi-arid grassland, Plant Soil 255: 513-528Google Scholar
- Xu LJ, Tang HJ, Yang GX, Wang X, Wang B, Xin XP (2011) Variation of net ecosystem carbon flux and its impact factors on Stipa baicalensis steppe in the growing season. Acta Prataculturae Sinica 20:287–292Google Scholar
- Yang GX, Tang HJ, Xin XP (2011) Chinese ecosystem station observation and research data-grassland and desert ecosystem-Hulunber Station Inner Mongolia (2006–2008), ChinaGoogle Scholar
- Zhang CH, Wang MJ, Zhao XH, Sun XL, Chen HJ, Wu RS (2014) Simulation of ANPP in response to climate change in China’s desert steppe based on CENTURY model. Chinese Journal of Ecology 33:2849–2857Google Scholar
- Zhou SX, Wu DX, Zhang L, Shi HQ (2010) Effects of changing precipitation patterns on seedlings of Stipa grandis, a dominant plant of typical grassland of Inner Mongolia, China. Chinese J Plant Ecol 34:1155–1164Google Scholar