海岸带生态恢复区不同林龄红树林对CH_4和CO_2排放通量的影响

Analysis on CH4 and CO2 Fluxes of Mangroves with Different Ages in the Coastal Ecological Restoration Zone

甲烷(CH_4)和二氧化碳(CO_2)是红树林湿地生态系统与大气交换的两种重要温室气体,是海岸带蓝碳通量观测和蓝色碳汇功能评估的重要组成参数,其产生排放过程受潮汐、土壤属性和树龄等综合因素的影响。利用理加便携式温室气体分析仪对浙江省南部鳌江口海岸带生态恢复区不同林龄红树林生态系统温室气体(CO_2和CH_4)排放通量进行实时在线监测,研究移植1年红树林幼苗和移植5年红树林生态恢复区温室气体排放通量变化趋势及其影响因素。通过研究温室气体通量随红树林植被的变化特征,为蓝碳收支估算提供重要数据基础,并为红树林湿地保护提供参考。结果表明,鳌江口海岸带生态恢复区不同林龄红树林蓝碳生态系统均为大气CH_4的排放源,平均CH_4排放通量为(0.67±0.06) mg·m^(-2)·h^(-1)(以C计,下同)。移植5年红树林生态恢复区为CO_2的吸收汇,其中高潮滩红树林平均通量为(-8263±2.29) mg·m^(-2)·h^(-1),低潮滩为(-26.05±17.94) mg·m^(-2)·h^(-1)。移植1年红树林幼苗恢复区为大气CO_2的排放源,平均排放通量为(96.95±46.94) mg·m^(-2)·h^(-1)。红树林植被的生物量对恢复区固碳增汇功能发挥有至关重要的作用。林龄是影响海岸带红树林恢复区蓝碳通量的重要影响因素,蓝碳收支估算中需要考虑林龄变化对碳汇功能的影响。

Methane(CH4)and carbon dioxide(CO2)are important greenhouse gases exchanged between mangrove wetland ecosystems and the atmosphere,and are important parameters for the observation of blue carbon fluxes and functional assessment of blue carbon sinks in coastal zones,affected by comprehensive factors such as tides,soil properties and tree age.In this paper,we used greenhouse gases automatic measurement system(SF-3000,USA,Lica United)to regularly monitor greenhouse gases(CO2 and CH4)emission fluxes in the mangrove ecosystems of different tree ages in the coastal ecological restoration zone,at the Aojiang Estuary in the southern Zhejiang Province.Impact of different tree ages with 5-year and 1-year transplantation of mangroves on greenhouse gases emission fluxes were studied.By studying the variation characteristics of greenhouse gas fluxes with mangrove vegetation,it provides an important data basis for blue carbon budget estimation and provides a reference for mangrove wetland protection.Results showed that the mangrove ecological restoration area in the coastal zone of the Aojiang Estuary was the source of atmospheric CH4 emissions,with the average CH4 flux value of(0.67±0.06)mg·m−2·h−1(calculated by C,the same below).The mangroves that had been transplanted for 5 years were the sinks of atmospheric CO2,with relatively higher carbon sink potential in the high tidal regions.The average CO2 flux of mangrove at high tide beach was(−82.63±22.9)mg·m−2·h−1,(−26.05±17.94)mg·m−2·h−1 at low tide beach.The young mangrove forests with the age of 1 year was the source of CO2 with the flux value of(196.95±46.94)mg·m−2·h−1.The biomass of mangrove vegetation played a vital role in the function of carbon sequestration and sink enhancement in the restoration area.It indicated that the tree age of mangrove forests should be considered when calculating the blue carbon budget.