【作者】 李熙波；

【导师】 杨玉盛；

【作者基本信息】 福建师范大学 ， 自然地理学， 2009， 硕士

【摘要】 本研究以亚热带人工马尼拉草草坪为研究对象,探讨了草坪生态系统CO₂净交换量（NEE）的两种观测方法——箱式红外气体分析法（IRGA法）和气相色谱法（GC法）的差异,分析了草坪生态系统NEE及碳平衡各分量的昼夜动态和季节动态的变化特征,以及各种环境因子和人为管理措施（修剪和灌溉）对NEE的影响,并估算了草坪生态系统NEE的年通量。主要结果如下:1)IRGA法对箱内环境的扰动小于GC法,其NEE观测结果比GC法的更接近真实值,但二者的观测结果具有极显著的线性相关关系（P＜0.01）。2)草坪生态系统NEE的昼夜动态呈单峰曲线,在白天表现为CO₂净吸收（负值）,正午前后达到吸收峰值,并与有效光合有效辐射的变化具有较好的一致性,而夜间为相对稳定的CO₂净排放（正值）。NEE正负值转换时间的变化受太阳高度角控制。另外,上午7:00观测草坪生态系统呼吸速率可以很好的代表全天呼吸速率均值。3)草坪生态系统NEE在夏季和冬季都为负值,表明其在夏季和冬季都可以吸收CO₂,即使在气温最低的2月份,仍呈现为一个较小的CO₂汇。并且夏季草坪生态系统的NEE值远低于冬季的。4)逐步回归分析表明:有效光合辐射、气温和土壤水分是草坪生态系统NEE的昼夜动态的主要影响因素。而主成分分析发现NEE的季节动态主要受水分、温度和光强等因子控制。5)修剪措施主要通过降低草坪生态系统的光合作用进而使草坪生态系统NEE增大,而浇水措施则通过促进生态系统呼吸使NEE增大。修剪对NEE的影响为3个月左右,在此期间,草坪生态系统的碳损失达202.20 g C·m^-2。相对于6:00浇水模式,18:00浇水模式对呼吸的促进作用更小,这主要是由较高的土壤含水量造成的。6)基于多因素的Michaelis-Menten改进模型,草坪生态系统的NEE年通量为-329.04 g C·m^-2·yr^-1,若考虑到修剪(1次·yr^-1)造成的碳损失,草坪生态系统的NEE年通量则为-126.84 g C·m^-2·yr^-1(-1.27 t C·hm^-2·yr^-1)。更多还原

【Abstract】 This study focused on the manilagrass lawn in the Minjiang Park of Fuzhou city, Fujian,China.A comparison was made between--chamber/infrared gas analyze method（IRGA method） and static chamber/gas chromatogram method（GC method） in evaluating CO₂ net ecosystem exchange（NEE）.The diurnal and seasonal variation of net ecosystem exchange（NEE） in manilagrass lawn ecosystem and its carbon balance components were also measured.The relationships were analyzed between the NEE of manilagrass lawn ecosystem and its various factors（environmental factors and human managements such as clipping and irrigation）.Then the annual NEE rate was estimated. The major results were followed:1) The disturbance to natural conditions in the IRGA chamber was weaker than that in the GC chamber.The values of the NEE rate measured by IRGA method were closer the ture values than that by GC method,but the results were strongly correlated.2) The diurnal variation of NEE showed a unimodal pattern in lawn ecosystem.In the daytime,CO₂ absorptions by lawn ecosystem were the strongest around at noon when it had the highest photosynthetically active radiation.While in the nighttime,lawn ecosystem emitted CO₂ at low rate.In addition,the ecosystem respiration rates measured at 7:00 could well represent the average flux value for the whole day.3) The lawn ecosystem could uptake CO₂ in both summer and winter,even in the coldest February.However,the rate of absorption in summer was generally higher than that in winter.4) The stepwise regression analysis showed that the key factors that controlled the diurnal variation of NEE were photosynthetically active radiation,air temperature and soil moisture.The principal component analysis discovered that the major factors of the seasonal variations of NEE were the observation indexes,which related to moisture temperature and light.5) The clipping plot promoted NEE rate mainly through reduing the gross canopy photosynthesis rates of lawn,while the irrigation plot increased NEE rate by promoting the respiration rate.The clipping effect had lasted about three months,during this period, it emited 202.20 g C·m^-2 into the atmosphere.Irrigation at different times had different effects on ecosystem respiration.The increase of the respiration resulted from the artificial irrigation at 18:00 was much smaller than that of the artificial irrigation at 6:00 because the soil moisture was much higher at 18:00 than that at 6:00.6) Based on multi-factor modifying Michaelis-Menten model,the annual NEE flux in lawn was estimated which was -329.04 g C·m^-2.yr^-1.However,the annual NEE flux was -126.84 g C·m^-2·yr^-1(-1.27 t C·hm^-2·yr^-1),if the carbon loss was added due to clipping.更多还原