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2008年4—6月利用LI-8100及LI-6400-09测定了华北平原典型冬小麦田土壤CO2通量,并分析了麦田土壤呼吸变化规律及其影响机制。结果表明:土壤呼吸日变化呈明显的单峰曲线,最高值出现在12:30—14:30,最低值出现在5:00—6:30;在不同的天气条件下,土壤呼吸速率晴天最高,多云其次,阴天最小;观测期间冠层内各高度CO2浓度与麦田土壤呼吸速率白天呈显著线性负相关,夜间正相关;土壤呼吸速率与5cm地温的季节变化趋势基本一致,二者显著指数相关;在田间持水量范围内,土壤呼吸速率与土壤湿度正相关,当土壤相对湿度低于30%时,土壤呼吸受到抑制而通量降低;综合考虑土壤温度与湿度的双因素指数回归模型能较好地解释土壤呼吸的变化情况,土壤温度低于15℃时效果更好。
Soil CO2 fluxes of typical winter wheat fields in North China Plain were measured using LI-8100 and LI-6400-09 from April to June 2008, and the variation of soil respiration and its mechanism were analyzed. The results showed that the diurnal variation of soil respiration showed a unimodal curve with the highest value occurring at 12: 30-14: 30 and the lowest value at 5: 00-6: 30. Under different weather conditions, the soil respiration rate was highest in sunny days , Followed by cloudy and cloudy days. During the observation period, the concentrations of CO2 in the canopy were significantly negatively correlated with the soil respiration rate in wheat field during the daytime and positively correlated with the nighttime during the observation period. The seasonal variations in soil respiration rate and 5cm soil temperature were basically the same, The soil respiration rate was positively correlated with soil moisture. When the soil relative humidity was less than 30%, the soil respiration was inhibited and the flux decreased. Considering the two-factor regression model of soil temperature and humidity Better explain the changes of soil respiration, the effect is better when the soil temperature is lower than 15 ℃.