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城市绿地的净生态系统CO2交换量(NEE)受多种环境因素控制,定量分析NEE的环境响应机制对评估绿地生态系统固碳效益、优化城市绿地布局有重要意义。本文应用2009、2010年位于东莞市植物园内的涡度相关CO2通量定位观测资料,分析了光合有效辐射(PAR)、土壤温度(Ts)、饱和水汽压差(VPD)、降水及周边不同下垫面类型对NEE的影响。结果表明:NEE绝对值随PAR的升高而增加,PAR超过光饱和点(约为1500μmol photons·m-2·s-1)后,NEE绝对值呈回落趋势;生态系统呼吸(Reco)随Ts升高而增加,在温度较低时,Reco对Ts的敏感性较强(10℃时,Lloyd-Taylor方程的Q10=1.8),随着温度升高,敏感性下降(30℃时,Q10=1.43);VPD通过影响植物气孔导度对CO2交换产生作用,相同温度下,随着VPD升高,气孔导度增大,呼吸释放与光合固定的CO2量均增加;降水能增加土壤湿度进而使Reco增大,25℃时,降水后的Reco比降水前增加15.8%;测站东北和西南方的绿地范围较大,当东北和西南部是主要贡献区时,NEE绝对值较大,表明增加城市绿地能有效提高城市固碳效益。
The net ecosystem CO2 exchange (NEE) of urban green space is controlled by many environmental factors. To quantitatively analyze the environmental response mechanism of NEE is of great significance to evaluate the carbon sequestration benefits of green space ecosystems and optimize the layout of urban green space. In this paper, the CO2 and CO2 fluxes in the Botanical Garden of Dongguan City in 2009 and 2010 were analyzed. The effects of PAR, soil temperature (Ts), VPD, precipitation, Effect of Type of Cushion on NEE. The results showed that the absolute value of NEE increased with the increase of PAR, and the absolute value of NEE decreased after PAR exceeded the light saturation point (about 1500μmol photons · m-2 · s-1). The ecosystem respiration (Reco) Reco is more sensitive to Ts at lower temperatures (Q10 = 1.8 for the Lloyd-Taylor equation at 10 ° C) and decreases with increasing temperature (at 30 ° C, Q10 = 1.43). VPD had an effect on the CO2 exchange by affecting the stomatal conductance. Under the same temperature, with the increase of VPD, the stomatal conductance increased, and the amount of CO2 released and photosynthetically fixed increased. The precipitation increased the soil moisture, Reco increased, Reco increased by 15.8% after rainfall precipitation at 25 ℃, and the green space in the northeast and southwest of the station was larger. When the northeast and southwest were the main contributing areas, the absolute value of NEE was larger, indicating an increase Urban green space can effectively improve the urban carbon sequestration benefits.