摘要
应用涡度相关法观测的通量数据和环境因子数据,在生态系统水平上分析了长白山阔叶红松林生长季温度与CO2通量之间的关系。结果表明:(1)在相同的光合有效辐射水平下,净生态系统CO2交换量(NEE)随温度Ta的变化趋势为,在Ta<20℃范围内,NEE随温度的增加而增加,在Ta=20℃附近有极大值,随温度的继续增加NEE呈下降的趋势,同时NEE还具有明显的季节变化,表现为7月>6月>8月>9月>5月>4月>10月。(2)应用MichaelisMenten方程计算得出最大光合速率Pmax和生态系统呼吸Re,分析其与温度的关系发现,Pmax随温度的变化呈S型曲线,Re则随着温度的升高而呈指数上升的趋势,曲线为:Re=0.0607exp(0.0666Ta),R2=0.96。夜间生态系统呼吸的Q10为3.15。(3)通过对NEE与环境因子的偏相关分析表明,温度对NEE的偏相关系数在生长季呈现先减小后增大的趋势,说明在生长季初期和末期升高温度比生长季中期对NEE的影响要大。
Forested ecosystems cover a large expanse of the terrestrial area in the world, which represent a large global sink of CO2, and strongly influence the dynamics of the global carbon cycle. In light of the current increase in atmospheric CO2 and warming climate, it is crucial to understand the mechanisms that control some ecological progresses in the forest ecosystems Studies of forest CO2 uptake have increased rapidly, especially after tower flux networks were established. However, the perspectives on net CO2 exchange at ecosystem-level are relatively new to plant ecophysiology.
In this study, based on eddy covariance system on tower, we continuously measured CO2 flux in the mixed forest of broadleaved and Korean-pine in Changbai Mountain in 2003. The relationship between CO2 flux and temperature at ecosystem-level during the growing season was analyzed. The results were as follows：
（1） When air temperature was below 20℃ in the definite range of photosynthetic activity radiation （ PAR）, the higher air temperature, the higher net ecosystem CO2 exchange （ NEE）. In contrast, when it was over 20℃, the higher air temperature, lower NEE. This effect was significantly different amongst seasons. It was mainly controlled by plant physiology and leaf the area index.
（2） NEE includes photosynthesis and respiration of ecosystem. Maximum photosynthetic rate Pmax and ecosystem respiration Re were calculated by Michaelis-Menten equation. The relationship between Pmax and air temperature exhibited S shaped curve, while Re was exponential to air temperature.
（3） The effects of canopy PAR, air temperature and vapor pressure deficit （VPD） on NEE were estimated respectively by partial correlation analysis and of difference amongst seasons. Partial correlation coefficients of temperature on NEE were higher in early and late growing period than that in the middle of growing seasons. It suggested that temperature in early and late growing seasons had more significant effects on NEE than that in the middle of growing seasons. Thus, we could identify the dynamic role that temperature played in controlling ecosystem fluxes during early and late seasons.
出处
《生态学报》
CAS
CSCD
北大核心
2006年第4期1088-1095,共8页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(30370293)
中国科学院知识创新工程重大项目(KZCX1_SW_01_01A1)~~
