氮和枯落物添加对闽江河口湿地土壤CO2释放的影响

Effects of Nitrogen and Litter Addition on Soil CO2 Release from the Minjiang River Estuary Wetlands

土壤CO2释放是土壤碳转化的关键过程。氮(N)添加及植物枯落物的分解对湿地土壤CO2释放速率有显著影响,在全球大气CO2浓度和气候变化中具有重要作用。本研究选取闽江河口湿地土壤为研究对象,通过24 d的短期培养实验,研究不同氮浓度和不同枯落物添加对闽江河口湿地土壤CO2释放速率的影响。结果表明:(1)短叶茳芏(Cyperus malaccensis)和互花米草(Spartina alterniflora)两种植物枯落物添加处理显著促进了湿地土壤CO2释放速率(P<0.05),也显著增加了闽江河口湿地土壤溶解性有机碳(DOC)、微生物量碳(MBC)和pH(P<0.05)。两种枯落物添加处理下,培养初期(0~9 d)枯落物可溶性有机碳快速释放和pH升高可能是导致土壤CO2释放峰值时间提前的主要因素。(2)枯落物添加后不同浓度氮输入对湿地土壤CO2释放速率均具有显著影响(P<0.001),但两种枯落物对土壤CO2释放速率的影响并无显著差异(P<0.05)。土壤微生物量碳(MBC)、土壤微生物量氮(MBN)的变化是影响不同枯落物在氮添加后培养前、后期土壤CO2释放差异的重要原因。

Soil CO2 release is a key process for soil carbon conversion.Nitrogen(N)addition and decomposition of litter have significant effects on CO2 release rate in wetland soils and play an important role in global atmospheric CO2 concentration and climate change.This study selected the wetland soil of the Minjiang River estuary as the research object.Through the short-term culture experiment of 24 d,the effects of different nitrogen concentrations and different litter additions on the CO2 release rate of the Minjiang River estuary wetland were studied.The results showed that:(1)The addition of litter of Cyperus malaccensis and Spartina alterniflora significantly promoted the release rate of CO2 in wetland soil(P<0.05),as well as the content of dissolved organic carbon(DOC),microbial biomass carbon(MBC)and pH(P<0.05).Rapid release of DOC and elevated pH of litter at the initial stage of culture(0~9 d)may be the main factors leading to the advance of peak time of soil CO2 release.(2)After the addition of litter,different concentrations of nitrogen input had significant effects on the CO2 release rate of the wetland soil(P<0.001),but the effects of the two litters on the CO2 release rate of the soil were not significantly different(P>0.05).Changes in soil microbial biomass carbon(MBC)and soil microbial biomass nitrogen(MBN)are important reasons for the differences in soil CO2 release in the earlier and later stage of incubation after nitrogen and litter addition.