马尾松作为中国东南部最大的有机碳库,在调节CO2、维持生物圈碳氧平衡过程中发挥着重要作用.该文基于涡度相关观测数据,从生态系统尺度分析了武夷山国家公园马尾松2019年生长季的碳源汇变化特征与影响因子,并对不同条件下的光合参数进行了拟合推算.结果表明:(1)马尾松净生态系统碳交换量(NEE)的生长季总量为-593.06 g CO2/m2;日尺度上,马尾松NEE的日变化特征均为"U"型,在12:00-14:00时碳汇能力最强;月总量上,马尾松9月碳汇能力最强(-94.55 gCO2/m2),而5-7月较弱.(2)光合有效辐射是日间碳交换的主导因子,两者呈显著负相关关系;土壤温度是夜间碳交换的主导因子,两者呈显著的二次函数关系.(3)光响应曲线表明,3月和7月马尾松生态系统的最大光合速率(Pmax)较高,而5月植被初始光能利用率(α)高;饱和水汽压差在1～2.5 kPa时Pmax和α均较大,最适合马尾松进行碳吸收;土壤含水量的上升会引起生态系统呼吸(Rd)、α和Pmax上升,当土壤含水量过饱和时,Rd的增量与Pmax相近,植被净固碳量保持稳定.研究结果有助于提高对马尾松生态系统碳汇功能的全面认识.
Abstract
The masson pine(Pinus massoniana,a coniferous tree species in the pine genus of the Pinaceae family)is the larg-est organic carbon reservoir in southeastern China,playing an important role in regulating CO2 and maintaining the carbon-ox-ygen balance of the biosphere.Based on turbulence flux observation data,this study analyzed the characteristics of carbon source and sink changes and influencing factors of the masson pine in Wuyishan National Park during the growing season of 2019 from the ecosystem scale,and estimated the photosynthetic parameters under different conditions.The results showed that the net ecosystem carbon exchange(NEE)of the masson pine during the growing season was-593.06 g CO2/m2.On the daily scale,the diurnal variation of NEE of masson pine was U-shaped,and the carbon sink capacity was strongest from 12 to 14 o'clock.On a monthly scale,carbon sequestration capacity of masson pine was strongest in September(-94.55 g CO2/m2)and relatively weak from May to July.Photosynthetically active radiation was the dominant factor of NEE at night,and there was a significant negative correlation between them.Soil temperature was the dominant factor of NEE at night,and the relationship between them showed a significant quadratic function.The light response curve shows that the maximum photo-synthetic rate(Pmax)of the masson pine ecosystem in March and July was higher,while the initial photosynthetic efficiency(α)of vegetation in May was higher.Both Pmax and α were larger when the vapor pressure deficit was between 1～2.5 kPa,which was the most suitable for the masson pine to absorb carbon.The increase of soil water content would lead to the increase of ecosystem respiration(Rd),α and Pmax.When soil water content was supersucated,the increment of Rd was similar to that of Pmax,and the net carbon sequestration of vegetation was no longer increasing.These results were helpful to improve the overall understanding of the carbon sink function of masson pine ecosystem.
关键词
武夷山国家公园/马尾松/碳源汇/影响因子/光响应曲线
Key words
Wuyishan National Park/masson pine/carbon source sink/impact factor/light response curve
维普
万方数据