The use of biogeochemical models to evaluate mitigation of greenhouse gas emissions from managed grasslands.
The use of biogeochemical models to evaluate mitigation of greenhouse gas emissions from managed grasslands.
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DOI：
10.1016/j.scitotenv.2018.06.020
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发表时间：
2018-11
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通讯作者：
R. Sándor;F. Ehrhardt;L. Brilli;M. Carozzi;S. Recous;Pete Smith;V. Snow;J. Soussana;C. Dorich;K. Fuchs;N. Fitton;Kate Gongadze;K. Klumpp;M. Liebig;Raphaël Martin;L. Merbold;P. Newton;R. Rees;S. Rolinski;G. Bellocchi
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作者：
R. Sándor;F. Ehrhardt;L. Brilli;M. Carozzi;S. Recous;Pete Smith;V. Snow;J. Soussana;C. Dorich;K. Fuchs;N. Fitton;Kate Gongadze;K. Klumpp;M. Liebig;Raphaël Martin;L. Merbold;P. Newton;R. Rees;S. Rolinski;G. Bellocchi
模拟模型量化了管理实践变化对草地系统碳(C)和氮(N)循环的影响。然而，为了支持农业政策，比较不同模式的反应是很重要的，这些模式在处理关键过程和对管理的反应方面可能有很大不同。我们在法国、新西兰、瑞士、英国和美国的5个草地上应用了8个生物地球化学模型，比较了模拟的C和N通量对放牧动物密度变化的敏感性（从原始牲畜密度的100%到50%），并结合氮肥水平的降低（从初始水平降至零）。多模型模拟值值表明,输入减少将导致增加C水槽强度(负净生态系统C交换)强化放牧系统:64− ± 74 g C m−2年−1(动物密度减少)和−81 ± 74 g C m−2年−1 (N和动物密度减少),对基线−30.5 ±69.5 g C m−2年−1 (LSU[牲畜单位] ≥0.76 ha−−1)1年。模拟还表明，氮肥减量对氮通量有很强的影响，例如N2O-N排放量从0.34 ± 0.22（基线）下降到0.1 ± 0.05 g N m−2yr−1（未施氮肥）。模拟放牧强度下降对氮平衡的影响有限。模拟的肠道甲烷排放模式主要受模式间高变异性的影响。模拟摄取量（动物摄取量 + 减少生物量）的减少导致每头动物净初级产量翻倍（各站点增加11.6 ± 8.1 t C LSU−1yr−1）。N2O-N强度（N2O-N/摄取量）在刈割和粗放放牧的干旱区最高。我们展示了利用草地模型确定合理缓解做法的可能性，同时量化了与模拟输出相关的不确定性。
Simulation models quantify the impacts on carbon (C) and nitrogen (N) cycling in grassland systems caused by changes in management practices. To support agricultural policies, it is however important to contrast the responses of alternative models, which can differ greatly in their treatment of key processes and in their response to management. We applied eight biogeochemical models at five grassland sites (in France, New Zealand, Switzerland, United Kingdom and United States) to compare the sensitivity of modelled C and N fluxes to changes in the density of grazing animals (from 100% to 50% of the original livestock densities), also in combination with decreasing N fertilization levels (reduced to zero from the initial levels). Simulated multi-model median values indicated that input reduction would lead to an increase in the C sink strength (negative net ecosystem C exchange) in intensive grazing systems: −64 ± 74 g C m−2yr−1(animal density reduction) and −81 ± 74 g C m−2yr−1(N and animal density reduction), against the baseline of −30.5 ± 69.5 g C m−2yr−1(LSU [livestock units] ≥ 0.76 ha−1yr−1). Simulations also indicated a strong effect of N fertilizer reduction on N fluxes, e.g. N2O-N emissions decreased from 0.34 ± 0.22 (baseline) to 0.1 ± 0.05 g N m−2yr−1(no N fertilization). Simulated decline in grazing intensity had only limited impact on the N balance. The simulated pattern of enteric methane emissions was dominated by high model-to-model variability. The reduction in simulated offtake (animal intake + cut biomass) led to a doubling in net primary production per animal (increased by 11.6 ± 8.1 t C LSU−1yr−1across sites). The highest N2O-N intensities (N2O-N/offtake) were simulated at mown and extensively grazed arid sites. We show the possibility of using grassland models to determine sound mitigation practices while quantifying the uncertainties associated with the simulated outputs.