Lugato Emanuele, Paniagua Lily, Jones Arwyn, de Vries Wim, Leip Adrian
European Commission, Joint Research Centre (JRC), Sustainable Resources Directorate, Ispra, Varese, Italy.
Wageningen University and Research, Environmental Systems Analysis Group, Wageningen, The Netherlands.
PLoS One. 2017 Apr 27;12(4):e0176111. doi: 10.1371/journal.pone.0176111. eCollection 2017.
Two objectives of the Common Agricultural Policy post-2013 (CAP, 2014-2020) in the European Union (EU) are the sustainable management of natural resources and climate smart agriculture. To understand the CAP impact on these priorities, the Land Use/Cover statistical Area frame Survey (LUCAS) employs direct field observations and soil sub-sampling across the EU. While a huge amount of information can be retrieved from LUCAS points for monitoring the environmental status of agroecosystems and assessing soil carbon sequestration, a fundamental aspect relating to climate change action is missing, namely nitrous oxide (N2O) soil emissions. To fill this gap, we ran the DayCent biogeochemistry model for more than 11'000 LUCAS sampling points under agricultural use, assessing also the model uncertainty. The results showed that current annual N2O emissions followed a skewed distribution with a mean and median values of 2.27 and 1.71 kg N ha-1 yr-1, respectively. Using a Random Forest regression for upscaling the modelled results to the EU level, we estimated direct soil emissions of N2O in the range of 171-195 Tg yr-1 of CO2eq. Moreover, the direct regional upscaling using modelled N2O emissions in LUCAS points was on average 0.95 Mg yr-1 of CO2eq. per hectare, which was within the range of the meta-model upscaling (0.92-1.05 Mg ha-1 yr-1 of CO2eq). We concluded that, if information on management practices would be made available and model bias further reduced by N2O flux measurement at representative LUCAS points, the combination of the land use/soil survey with a well calibrated biogeochemistry model may become a reference tool to support agricultural, environmental and climate policies.
欧盟2013年后共同农业政策（CAP，2014 - 2020年）的两个目标是自然资源的可持续管理和气候智能型农业。为了解CAP对这些优先事项的影响，土地利用/覆盖统计区域框架调查（LUCAS）在欧盟范围内采用了直接实地观测和土壤子采样。虽然可以从LUCAS点获取大量信息来监测农业生态系统的环境状况和评估土壤碳固存，但与气候变化行动相关的一个基本方面却缺失了，即一氧化二氮（N₂O）的土壤排放。为填补这一空白，我们针对11000多个农业用途的LUCAS采样点运行了DayCent生物地球化学模型，并评估了模型的不确定性。结果表明，当前年度N₂O排放量呈偏态分布，均值和中值分别为2.27和1.71千克氮/公顷·年。通过随机森林回归将模拟结果扩展到欧盟层面，我们估计N₂O的直接土壤排放量在171 - 195太克二氧化碳当量/年的范围内。此外，利用LUCAS点模拟的N₂O排放量进行区域直接扩展，平均为0.95兆克二氧化碳当量/公顷·年，这在元模型扩展范围（0.92 - 1.05兆克二氧化碳当量/公顷·年）内。我们得出结论，如果能够提供管理实践信息，并通过在具有代表性的LUCAS点进行N₂O通量测量进一步减少模型偏差，那么土地利用/土壤调查与校准良好的生物地球化学模型相结合可能会成为支持农业、环境和气候政策的参考工具。
