亚热带马尼拉草坪生态系统呼吸昼夜变化研究初报

采用Li-8100对亚热带马尼拉草坪生态系统呼吸及其分室昼夜动态进行研究，结果表明，草坪生态系统呼吸、土壤呼吸和植物地上部分呼吸速率的昼夜变化均表现为单峰曲线，呼吸速率日最高值出现在中午13：00～14：00；草坪生态系统的呼吸速率最低值只出现在6月的7：00左右，其他月份的最低值出现在23：00～2：00；土壤呼吸速率的最低值出现在4月和6月的7：00左右，8月则在2：00达最低值，11月土壤呼吸速率波动不大，极值不太明显．生态系统呼吸速率始终表现为白天高于夜间．4月、6月、8月和11月生态系统呼吸的日排放C量分别为27．30、43．94、44．79和25．18g m^2d^-1．6月、8月和11月土壤日呼吸量占整个生态系统日呼吸总量的比例大约为50％，远小于4月的74％．除11月外，生态系统、土壤总呼吸速率的昼夜变化均与5cm土温呈显著的指数相关．草坪生态系统呼吸的Q10值大小顺序为4月〉11月〉6月〉8月，土壤总呼吸的Q10值大小顺序为6月〉4月〉8月〉11月；除11月外，土壤呼吸的Q10值大于生态系统呼吸．

Primary Study on Diurnal Respiration Variation of Subtropical Manilagrass Lawn Ecosystem

The diurnal variation in respiration of manilagrass lawn ecosystem and its components, soil and aboveground plant, in the Minjiang Park, Fujian, China were measured using a LI-8100 system. All kinds of these respiration showed a single daily peak, with maximal respiration rate appearing at 13： 00-14： 00. Only in June, the minimal respiration rate of lawn ecosystem was observed at around 7： 00, for other months, the lowest rate would appeared at 23： 00-2： 00. For soil respiration, the minimal rate was observed at 7：00 in April and June, but at 2：00 if the time was August, and in November, no obvious fluctuation and peak value could be observed. With no exception, the daytime ecosystem respiration rate was greater than that at night. The daily CO2 emissions through ecosystem respiration in April, June, August and November were 27.30, 43.94, 44.79 and 25.18g C m^2 d^-1, respectively. Soil respiration accounted for 52.93% of ecosystem respiration in June, August and November, and 74.12% in April. Except in November, there was a significantly positive correlation between respiration rate and soil temperature at 5 cm depth. For ecosystem respiration in the lawn, the Ql0 value showed an order of April〉November〉June〉August, but of June〉 April〉August〉November for soil respiration. Except in November, the Q10 value of ecosystem respiration was lower than that of soil respiration.