洞庭湖白沙洲4种植被系统与大气中碳素交换

The exchange between four types of vegetation system of Baishazhou in Dongting Lake and carbon of atmosphere

近年来由于气候变化,极端天气现象及其相应的自然灾害的频繁发生,致使人类面临严峻的挑战,全球环境问题已备受瞩目。湿地碳循环在全球气候变化中具有不可忽视的作用,研究湿地系统与大气中碳素的交换,有助于深入了解湿地生态系统对大气环境的影响。在生物量和土壤温室气体排放测定的基础上,对洞庭湖白沙洲湿地4种主要植被系统与大气碳素交换进行研究,结果表明:杨树人工林、芦苇和苔草3种植被系统净生产力吸收大气中碳量分别为9.88、6.83.thm-.2a-1和4.07.thm-.2a-1,土壤排放碳量(包括CH4中的碳素)分别为3.08、2.79.thm-.2a-1和2.80t.hm-.2a-1,3种植被系统每年净吸收大气中的碳6.80、4.07t.hm-.2a-1和1.27t.hm-.2a-1,都是大气CO2的汇;黑藻与竹叶眼子菜混交群落净生产力吸收大气碳1.23.thm-.2a-1,土壤排放的碳1.32t.hm-.2a-1,该系统每年向大气净排放0.09t.hm-.2a-1,是一个弱的CO2排放源;将CH4温室效应是CO2的21倍折算成CO2量,杨树林土壤排放CO2量(包括CH4折算成CO2量)为16.19t.hm-.2a-1,比植被净生产力吸收的少16.64t.hm-.2a-1,对大气温室效应而言,该系统是温室气体的汇;芦苇、苔草以及黑藻与竹叶眼子菜混交群落土壤排放CO2量(包括CH4折算成CO2量)分别是43.68、39.19t.hm-.2a-1和32.22t.hm-.2a-1,比植被净生产力吸收的还多20.60、24.27.thm-.2a-1和27.71.thm-.2a-1,对大气温室效应而言,这3种湿地植被系统都是温室气体排放源。

Due to climate change in recent years,extreme weather and corresponding natural disasters are frequently occurring,and people face severe challenges.Global environmental problem has attached a lot of attention.Wetland is one of the four terrestrial ecosystem.Although the world＇s wetland only accounts for 4%-5% of the total land area,its carbon storage is up to 450Gt,equivalent to 20% of carbon in global terrestrial ecosystem.Wetland ecosystem doubles as carbon sink and carbon resource.Carbon cycle has an important influence on global carbon budget and global climate change.Researching the exchange between wetland system and carbon of atmosphere contributes to thoroughly understand the effects that wetland ecological system act on environment of atmosphere.On the basis of biomass and determining green house gas emission,the exchange between four types of vegetation system of Baishazhou in Dongting Lake and carbon of atmosphere were studied.The results indicated：Poplar plantation、Phragmites and Carex these three types vegetation system its productivity respectively Absorb carbon9.88、6.83 t·hm-2·a-1 and 4.07 t·hm-2·a-1,Carbon emitted by soil（including carbon of CH4）3.08、2.79 t·hm-2·a-1 and 2.80 t·hm-2·a-1,the three types vegetation system are sink which Absorbs carbon 6.80、4.07 t·hm-2·a-1 and 1.27 t·hm-2·a-1every year.Mictium of Hydrilla and Potamogeton its net productivity Absorb carbon 1.23 t·hm-2·a-1,soil discharge carbon 1.32 t·hm-2·a-1,the system is carbon source,which discharge carbon 0.09 t hm-2·a-1every year.If that CH4 green house effect is 21 times of CO2 convert into CO2,soil of Poplar forestry release CO2（including CH4converting into CO2）16.19 t hm-2·a-1,which is less 16.64 t·hm-2·a-1than net productivity of vegetation.This system is sink of green house for green house effect of atmosphere;Phragmites、Carex as well as mictium of Hydrilla and Potamogeton.Soil release CO2（including CH4converting into CO2）43.68、39.19and 32.22 t·hm-2·a-1,which is more 20.26 、24.27and27.71 t·hm-2·a-1 than vegetation net productivity Absorbing.These three types wetland vegetation system are emission source of green house gas for green house effect of atmosphere,which reminds us that in the wetland study,we not only concentrate wetland soil organic carbon on accumulation of loss,but also care about CO2 which may be carbon sink of atmosphere or sources of emissions of atmospheric greenhouse effect.