物种丰富的异龄老龄森林对陆地生态系统动态模型及全球碳收支具有十分重要的意义.目前,我国关于老龄森林碳通量的研究很少,亚热带地区的老龄林更鲜有报道.本研究利用涡度相关技术观测了我国中亚热带地区的浙江天目山一个老龄常绿落叶阔叶混交林生态系统的CO2通量.以2013年7月到2014年6月的观测数据为依据,分析了此老龄林净生态系统碳交换量(NEE)、生态系统呼吸量(Re)、生态系统总交换量(GEE)的变化.结果表明:研究期间,老龄林常绿落叶阔叶混交林生态系统NEE月总量除12、2月为正值外(表现为碳源),其余月份均为负值(表现为碳汇).NEE月总量平均为-61.52 g C·m-2,各月碳吸收量以6月(-149.40 g C·m-2)最高,10月次之,呈双峰变化;最大碳源出现在2月(23.45 gC·m-2).各月NEE平均日变化差异明显,6月的平均通量峰值最大,达到-0.98 mg·m-2 · s-1,12月最小,为-0.35 mg·m-2·s-1;NEE符号改变的时间也呈明显的季节变化特征;全年NEE、Re、GEE分别为-738.18、931.05、-1669.23 g C·m-2.与相近纬度相近林型的其他森林生态系统相比,由于其复层结构和多种幼龄更新树木的存在,其测定的固碳量较大.表明我国中亚热带天目山地区的老龄森林生态系统不是处于碳收支稳定状态,而是具有相对较高的固碳能力.
Characteristics of CO2 flux in an old growth mixed forest in Tianmu Mountain, Zhejiang,China
The old-growth,multiple ages,multispecies natural forest has played an important role in terrestrial ecosystem dynamics model and the global carbon budget.However,carbon fluxes of old forests in subtropical regions are rarely reported in China.In the present study,the CO2 flux of an old-growth subtropical evergreen and deciduous broad-leaved mixed forest was observed using eddy covariance technique in Tianmu Mountain of Zhejiang Province.Based on the data sets which were observed from July 2013 to June 2014,the variations of net ecosystem exchange (NEE),ecosystem respiration (Re),and gross ecosystem exchange (GEE) were analyzed.The results showed that during the study period,the monthly NEE all had a negative value (acted as a carbon sink) except for December and February (acted as a carbon source).The average monthly NEE was-61.52 g C · m-2,the monthly carbon sequestration showed a double-peak curve and the maximum carbon sink was-149.40 g C · m-2,which occurred in June,while the maximum carbon source was 23.45 g C · m-2,which occurred in February.The maximum of monthly mean CO2 flux occurred in June with a value of-0.98 mg · m-2 · s-1,while the minimum value occurred in December with a value of-0.35 mg · m-2 · s-1.The NEE at the time point of positive and negative conversion had typical seasonal characteristics.The yearly NEE,Re,and GEE were-738.18,931.05 and-1669.23 g C · m-2,respectively.Compared with other forest ecosystems located at the similar latitude,the carbon fixation of the old-growth forest was larger,likely due to its complicated structure within the canopy and the presence of young-growth regeneration and successional stands.This showed that other than in carbon neutral,old-growth forests of Tianmu Mountain in subtropical China had a strong capability in carbon sequestration.
国家科技期刊平台
NSTL
万方数据
维普
