南北过渡带常绿落叶阔叶混交林碳通量特征及其对环境因子的响应

Carbon flux characteristics and responses to environmental factors in the evergreen⁃deciduous broadleaf mixed forest of the north⁃south transitional zone

森林生态系统强大的碳源/汇功能是实现“碳中和”和“碳达峰”战略目标最经济、有效的自然气候解决方案和固碳增汇手段。准确评估森林生态系统的碳汇能力,对于明确森林碳储量有重要意义。为明确亚热带-暖温带气候过渡带的常绿落叶阔叶混交林的碳通量特征及其驱动因素,2011—2020年利用涡度相关法开展了大别山常绿落叶阔叶混交林碳通量和环境要素的观测试验。结果表明:大别山常绿落叶阔叶混交林净生态系统CO_(2)交换量、生态系统呼吸(Reco)、总初级生态生产力分别为-788.13 gC m^(-2) a^(-1)、1074.14 gC m^(-2) a^(-1)、1862.27 gC m^(-2) a^(-1),该森林生态系统整体表现为碳汇,其固碳能力与相近纬度的常绿落叶阔叶混交林基本持平,并高于针阔叶混交林、毛竹林等其他类型的森林生态系统。10年间,大别山常绿落叶阔叶混交林的固碳能力有所增强。影响大别山常绿落叶阔叶混交林碳通量的主要环境因子为温度与太阳辐射,气温(Ta)、净辐射(Rn)、光合有效辐射和总辐射与生态系统碳生产力和GPP呈显著正相关(P<0.001),Reco与Ta和Rn呈显著正相关(P<0.001)。研究结果为气候变化响应敏感的南北气候过渡带森林生态系统的碳储量估算、碳循环过程模拟提供观测数据支持和科学依据。

The robust carbon source/sink function of forest ecosystems is identified as the most economical and effective natural climate solution for achieving the strategic objectives of carbon neutrality and carbon peaking.Accurately assessing the carbon sequestration capability of forest ecosystems is crucial for determining forest carbon storage.In order to clarify the carbon flux characteristics and their driving factors in the evergreen⁃deciduous broadleaf mixed forest in the North⁃South climate transition zone,observations of carbon flux and environmental factors were conducted in the Dabie Mountains′evergreen⁃deciduous broadleaf mixed forest using eddy covariance method from 2011 to 2020.The results revealed that the net ecosystem exchange(NEE),ecosystem respiration(Reco),and gross primary productivity(GPP)of this forest were-788.13 gC m^(-2) a^(-1),1074.14 gC m^(-2) a^(-1),and 1862.27 gC m^(-2) a^(-1),respectively.This forest ecosystem was overall a carbon sink,with its carbon sequestration capacity being comparable to similar latitude evergreen⁃deciduous broadleaf mixed forests and higher than other types of forest ecosystems like the mixed coniferous⁃broadleaf forests and bamboo forests.Over a decade,the carbon sequestration capacity of the Dabie Mountains′evergreen⁃deciduous broadleaf mixed forest has increased.The carbon flux in this forest was significantly influenced by temperature and solar radiation.Air temperature(Ta),net radiation(Rn),Photosynthetically Active Radiation(PAR),and total radiation(Rg)showed significantly positive correlation with the ecosystem′s Net Ecosystem Productivity(NEP)and GPP(P<0.001);Reco showed significantly positive correlation with Ta and Rn(P<0.001).The findings provide observational data support and scientific basis for the estimation of carbon storage and simulation of carbon cycling processes in forest ecosystems of the north⁃south climatic transitional zone,which are sensitive to climate change.