To investigate the short-term effects of grassland renovation on carbon dioxide (CO2) exchange of intensively managed grasslands in Japan, we conducted CO2 flux measurements during the renovation process by using the eddy covariance and closed chamber methods in 2007, 2012, and 2013. The flux measurements were conducted at three grassland fi elds: two fi elds used for cutting, one receiving only chemical fertilizer (CF) and the other receiving composted cattle manure (CM) annually, and one fi eld used for grazing (GM). Chamber measurements revealed fl ushes of CO2 after plowing (14.45-23.94 μmol m s) and subsequent disk harrowing (7.36 μmol m s, in CF) followed by rapid drops of CO2 flux, which were local and temporary phenomena. The mean CO2 losses during renovation periods were calculated as 4.52-4.74, 6.00-6.81, and 4.57 g C m d in CF, CM, and GM, respectively; CF and CM calculation is based on eddy covariance measurements, including temporal fl ux variations and representing footprint areas. The amount of carbon input during renovation including non-harvested grass biomass (stubble and roots) and applied manure was estimated as 2.24-3.50 and 6.17-8.77 Mg C ha in CF and CM, respectively. Among them, carbon derived from plowed roots and manure is presumably resistant in soil, contributing to long-term soil organic carbon (SOC) accumulation. Our results also indicate that grassland renovation work does not affect short-term net CO2 loss signifi cantly, although it affects CO2 emissions to a certain extent. We can therefore say that net CO2 loss during renovation is mainly brought by the absence of vegetation in this site. Grasses contribute SOC accumulation through biomass allocation belowground; and it is thus recommended to shorten grassland renovation period, the duration without photosynthesis, to reduce CO2 loss associated with grassland renovation.

中文翻译：

---

温带湿润地区草地改造对草地CO ₂交换的短期影响

为了研究草地改造对日本集约化管理草地二氧化碳 (CO2) 交换的短期影响，我们在 2007、2012 和 2013 年使用涡流协方差和密闭室方法在改造过程中进行了 CO2 通量测量。通量测量在三个草地领域进行：两个领域用于切割，一个每年只接受化肥（CF），另一个接受堆肥牛粪（CM），一个用于放牧（GM）。腔室测量显示在耕作（14.45-23.94 μmol ms）和随后的圆盘耙（7.36 μmol ms，在 CF 中）之后 CO2 大量涌出，随后 CO2 通量迅速下降，这是局部和暂时现象。翻新期间的平均 CO2 损失计算为 4.52-4.74、6.00-6.81 和 4.57 g C md，在 CF、CM、和通用汽车，分别；CF 和 CM 计算基于涡流协方差测量，包括时间通量变化和代表足迹区域。改造期间的碳输入量，包括未收获的草生物量（茬和根）和施用的粪肥，在 CF 和 CM 中估计分别为 2.24-3.50 和 6.17-8.77 Mg C ha。其中，来自犁过的根和粪便的碳可能在土壤中具有抗性，有助于土壤有机碳 (SOC) 的长期积累。我们的研究结果还表明，草原整治工作对短期 CO2 净损失没有显着影响，尽管它在一定程度上影响了 CO2 排放。因此，我们可以说改造期间的净 CO2 损失主要是由于该场地没有植被造成的。草通过地下生物量分配促进 SOC 积累；因此建议缩短草原整治期，即无光合作用的持续时间，以减少与草原整治相关的二氧化碳损失。