To investigate the reasons for irregular and severe decreases in net ecosystem production (NEP) in a sod-cultured apple orchard for better understanding orchard carbon dynamics, CO₂ flux observation was conducted from April to November (2013 and 2014) using two sets of eddy covariance equipment on different towers that were 15 m apart. Special attention was paid to the effect of grass mowing, which was conducted ten times during the observation period. In the latter half of, or just after the grass mowing period, gross primary production (GPP) on fine (sunny) days decreased to 50%-73% of the level before the grass mowing nine out of ten times, whereas ecosystem respiration (RE) did not decrease or slightly increased. As a result, NEP (=GPP－RE) on fine days drastically diminished after every grass mowing event. Moreover, three other moderate NEP decreases were observed, in addition to mowing events. Two of these events, which occurred 9-10 days before apple flowering, were possibly caused by a temporal increase in the respiration of apple tree. The remaining event, which occurred immediately after the drought period, was possibly caused by the recovery of microorganism and root respirations. Moreover, in comparing the daily GPP trend in 2013 and 2014, it was apparent that meteorological conditions, such as low temperature from April to May or severe soil water deficiency and low solar radiation in the vigorous growth stage, also negatively affected the population photosynthesis of the orchard.

为调查草培苹果园生态系统净产量 ( NEP )　不规则和严重下降的原因，以更好地了解果园碳动态，在 4 月至 11 月（2013 年和 2014 年）期间使用两组涡流观测进行了CO ₂通量观测相距 15 m 的不同塔上的协方差设备。特别注意割草的效果，在观察期间进行了十次。在割草期的后半期或刚结束时，晴天（晴天）的初级生产总值（GPP）在十次中有九次下降到割草前水平的 50%-73%，而生态系统呼吸（RE ) 没有减少或略有增加。因此，晴天的NEP (= GPP－RE ) 在每次割草事件后急剧减少。此外，除了割草事件外，还观察到另外三个中度NEP下降。其中两个事件发生在苹果开花前 9-10 天，可能是由于苹果树的呼吸作用暂时增加所致。其余事件发生在干旱期之后，可能是由微生物和根系呼吸的恢复引起的。此外，在比较每日GPP从 2013 年和 2014 年的趋势来看，4-5 月气温偏低或旺盛期土壤严重缺水、太阳辐射偏低等气象条件也对果园种群光合作用产生了不利影响。