模拟火干扰对森林土壤微生物活性及氮矿化的影响
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摘要
火干扰产生热能从而诱导土壤有机质的化学氧化,改变碳和氮转换,对土壤的结构与功能产生严重影响,影响程度取决于火强度、火干扰持续时间和热渗透。在湖南省株洲市高枧林场选取马尾松次生林火烧迹地,按两种土壤、3个温度和3种土壤水势进行试验设计与方差分析,探讨火干扰对土壤微生物及氮矿化的影响。结果表明:无机氮的浓度与火强度和初始土壤有机质含量呈正相关关系;火干扰后短期内土壤碳和氮浓度较高,微生物生物量碳和潜在可矿化氮较低,温度和土壤水势对基础呼吸速率没有显著影响;当土壤温度达160℃时,未受火干扰土壤中潜在可矿化氮浓度迅速不稳定增加,温度达350℃时破坏90%的非微生物组织;土壤加热后水势对氮矿化过程有显著影响,水势越高,潜在可矿化氮损失越大,火干扰土壤的含水量与硝态氮之间呈正相关关系;培养14d期间,土壤火灾历史、热处理和土壤水势对微生物活性、碳和氮矿化有显著影响,-1.5 MPa水势下加热到380℃后两种土壤的微生物生物量碳含量最高,土壤水势和可溶性糖呈负相关关系;水势和火干扰之间的交互作用显著影响微生物活性和氮转换,低水势土壤中的微生物生物量碳、可溶性糖和潜在可矿化氮浓度较高。
Heat from fire disturbance induces chemical oxidation of soil organic matter that alters the conversion of carbon(C)and nitrogen(N),which seriously influences soil structure and functions.However,the extent of oxidation depends on the fire intensity and duration,and heat penetration.In the present study,a burned area of Pinus massoniana secondary forest located in the Gaojian State Forest Farm,Zhuzhou,Hunan Province,was selected to conduct an experiment of the effects of fire disturbance on microbial activity and N mineralization of forest soil.The experiment was conducted in a completely randomized design based on two kinds of soil,three different temperatures,and three soil water potentials,with each treatment replicated three times.A variance analysis was performed on the data.The results showed the concentration of inorganic N and initial soil organic matter content were positively correlated with fire intensity.Shortly after fire disturbance,soil C and N concentration were high,but microbial biomass C and potentially mineralized nitrogen(PMN)were low,and temperature and soil water potential had no significant effect on the basic respiration.PMN loss was observed in the unheated control soils of fire disturbance compared with soils not exposed to fire.When soil temperature reached 160℃,it resulted in only a modest increase in PMN concentrations in the soil not previously exposed to fire.If soil temperature exceeded 160℃,the PMN content fluctuated,and then increased rapidly.A soil temperature of 350℃ resulted in the destruction of90% non-microbial tissues.The soil water potential after heating had a significant effect on N mineralization:the higher the soil water potential,the more the PMN loss.There was a positive correlation between the water content of fire disturbed soil and nitrate N.During the 14 day incubation,microbial activity and C and N mineralization were significantly influenced by soil fire history,initial heat treatment,and soil water potential.The release of soil available C and N from fire disturbance supported the recovery of microbial activity in low water potentials.When soil was heated to 380℃ at-1.5 MPa water potential,soil microbial biomass C was the highest in both soils.A negative correlation between soil water potential and soluble sugar was observed for both soils.The concentration of soluble anthrone reactive carbon(ARC)dropped significantly(P<0.05)in both soils over time,resulting from the microbial consumption of sugars released from the fire disturbance.The interaction between water potential and fire disturbance significantly affected the microbial activity and N conversion,and in low water potential soil,microbial biomass C,soluble sugar,and PMN were high.Newly formed labile N by fire disturbance was protected in soil with low water potential.Labile N remained lower in moist than in dry soils regardless of soil fire history.
Heat from fire disturbance induces chemical oxidation of soil organic matter that alters the conversion of carbon(C)and nitrogen(N),which seriously influences soil structure and functions.However,the extent of oxidation depends on the fire intensity and duration,and heat penetration.In the present study,a burned area of Pinus massoniana secondary forest located in the Gaojian State Forest Farm,Zhuzhou,Hunan Province,was selected to conduct an experiment of the effects of fire disturbance on microbial activity and N mineralization of forest soil.The experiment was conducted in a completely randomized design based on two kinds of soil,three different temperatures,and three soil water potentials,with each treatment replicated three times.A variance analysis was performed on the data.The results showed the concentration of inorganic N and initial soil organic matter content were positively correlated with fire intensity.Shortly after fire disturbance,soil C and N concentration were high,but microbial biomass C and potentially mineralized nitrogen(PMN)were low,and temperature and soil water potential had no significant effect on the basic respiration.PMN loss was observed in the unheated control soils of fire disturbance compared with soils not exposed to fire.When soil temperature reached 160℃,it resulted in only a modest increase in PMN concentrations in the soil not previously exposed to fire.If soil temperature exceeded 160℃,the PMN content fluctuated,and then increased rapidly.A soil temperature of 350℃ resulted in the destruction of90% non-microbial tissues.The soil water potential after heating had a significant effect on N mineralization:the higher the soil water potential,the more the PMN loss.There was a positive correlation between the water content of fire disturbed soil and nitrate N.During the 14 day incubation,microbial activity and C and N mineralization were significantly influenced by soil fire history,initial heat treatment,and soil water potential.The release of soil available C and N from fire disturbance supported the recovery of microbial activity in low water potentials.When soil was heated to 380℃ at-1.5 MPa water potential,soil microbial biomass C was the highest in both soils.A negative correlation between soil water potential and soluble sugar was observed for both soils.The concentration of soluble anthrone reactive carbon(ARC)dropped significantly(P<0.05)in both soils over time,resulting from the microbial consumption of sugars released from the fire disturbance.The interaction between water potential and fire disturbance significantly affected the microbial activity and N conversion,and in low water potential soil,microbial biomass C,soluble sugar,and PMN were high.Newly formed labile N by fire disturbance was protected in soil with low water potential.Labile N remained lower in moist than in dry soils regardless of soil fire history.
引文
[1]Fernández I,Cabaneiro A,Carballas T.Organic matter changes immediately after a wildfire in an Atlantic forest soil and comparison with laboratory soil heating.Soil Biology and Biochemistry,1997,29:1-11.
[2]Hungerford R D,Harrington M G,Frandsen W H,Ryan K C,Niehoff G J.Influence of fire factors that affect site productivity//Harvey A E,Neuenschwande L F,eds.Proceeding of the Management and Productivity of Western Montane Forest Soils.Intermountain Research Station General Technical Report INT-280.USDA-FS,1991:32-50.
[3]Hernández T,García C,Reinhardt I.Short-term effect of wildfire on the chemical,biochemical and microbiological properties of Mediterranean pine forest soils.Biology and Fertility of Soils,1997,25:109-116.
[4]Neary D G,Klopatek C C,DeBano L F,Folliott P F.Fire effects on belowground sustainability:a review and synthesis.Forest Ecology and Management,1999,122:51-71.
[5]Díaz-Ravi1a M,Prieto A,Bth E.Bacterial activity in a forest soil after soil heating and organic amendments measured by the thymidine and leucine incorporation technique.Soil Biology and Biochemistry,1996,28:419-426.
[6]Giovannini G,Lucchesi S,Giachetti M.Effects of heating on some chemical parameters related to soil fertility and plant growth.Soil Science,1990,149:344-350.
[7]Campbell G S,Jungbauer J D,Bidlake W R,Hungerford R D.Predicting the effect of temperature on soil thermal conductivity.Soil Science,1994,158:307-313.
[8]Albini F A,Reinhardt E D.Modeling ignition and burning rate of large woody natural fuels.International Journal of Wildland Fire,1995,5:81-91.
[9]Baker K F.Selective killing of soil microorganisms by aerated steam//Toussoun T A,Bega R V,Nelson P E,Eds.Root Disease and SoilBorne Pathogens.University of California Press,1970:234-238.
[10]陶玉柱.火对塔河森林土壤微生物及酶活性的干扰作用[D].哈尔滨:东北林业大学,2014.
[11]杨玉莲.模拟增温对高山森林土壤微生物和酶活性的影响[D].雅安:四川农业大学,2012.
[12]Arno S F,Harrington M G,Fiedler C F,Carlson C E.Restoring fire-dependent ponderosa pine forests in Western Montana.Restoration Management Notes,1995,13:32-36.
[13]Dunn P H,Barro S C,Poth M.Soil moisture affects survival of microorganisms in heated chaparral soil.Soil Biology and Biochemistry,1985,17:143-148.
[14]吕爱锋,田汉勤,刘永强.火干扰与生态系统的碳循环.生态学报,2005,25(10):2734-2743.
[15]韩春兰,邵帅,王秋兵,李甄,孙仲秀,毛伟伟.兴安落叶松林火干扰后土壤有机碳含量变化.生态学报,2015,35(9):3023-3033.
[16]Yang J E,Skogley E O,Schaff B E,Kim J J.A simple spectro-photometric determination of nitrate in water,resin,and soil extracts.Soil Science Society of America Journal,1998,62:1108-1115.
[17]Joergensen R G,Brookes P C.Ninhydrin-reactive N measurements of microbial biomass in 0.5 m K2SO4soil extracts.Soil Biology and Biochemistry 1990,22(8):1023-1027.
[18]DeLuca T H,Keeney D R.Ethanol stabilized chloroform as a fumigant for estimating microbial biomass by reaction with ninhydrin.Soil Biology and Biochemistry,1993,25:1297-1298.
[19]Zibilske L M.Carbon mineralization.Soil Science Society of America,1994:835-863.
[20]SAS Institute.SAS user′s guide.6th ed.Cary,NC:SAS Institute,1995.
[21]Raich JW,Potter CS.Global pat terns of carbon dioxide emissions from soils.Global Biogeochem Cycles,1995,9:23-36
[22]Choromanska U,DeLuca T H.Prescribed fire alters the impact of wildfire on soil biochemical properties in a ponderosa pine forest.Soil Science Society of America Journal,2001,65:232-238.
[23]Pietikinen J,Hiukka R,Fritze H.Does short-term heating of forest humus change its properties as a substrate for microbes?.Soil Biology and Biochemistry,2000,32:277-288.
[24]刘发林,张思玉.火干扰下马尾松林物种多样性和土壤养分特征.西北林学院学报,2009,24(5):36-40.
[2]Hungerford R D,Harrington M G,Frandsen W H,Ryan K C,Niehoff G J.Influence of fire factors that affect site productivity//Harvey A E,Neuenschwande L F,eds.Proceeding of the Management and Productivity of Western Montane Forest Soils.Intermountain Research Station General Technical Report INT-280.USDA-FS,1991:32-50.
[3]Hernández T,García C,Reinhardt I.Short-term effect of wildfire on the chemical,biochemical and microbiological properties of Mediterranean pine forest soils.Biology and Fertility of Soils,1997,25:109-116.
[4]Neary D G,Klopatek C C,DeBano L F,Folliott P F.Fire effects on belowground sustainability:a review and synthesis.Forest Ecology and Management,1999,122:51-71.
[5]Díaz-Ravi1a M,Prieto A,Bth E.Bacterial activity in a forest soil after soil heating and organic amendments measured by the thymidine and leucine incorporation technique.Soil Biology and Biochemistry,1996,28:419-426.
[6]Giovannini G,Lucchesi S,Giachetti M.Effects of heating on some chemical parameters related to soil fertility and plant growth.Soil Science,1990,149:344-350.
[7]Campbell G S,Jungbauer J D,Bidlake W R,Hungerford R D.Predicting the effect of temperature on soil thermal conductivity.Soil Science,1994,158:307-313.
[8]Albini F A,Reinhardt E D.Modeling ignition and burning rate of large woody natural fuels.International Journal of Wildland Fire,1995,5:81-91.
[9]Baker K F.Selective killing of soil microorganisms by aerated steam//Toussoun T A,Bega R V,Nelson P E,Eds.Root Disease and SoilBorne Pathogens.University of California Press,1970:234-238.
[10]陶玉柱.火对塔河森林土壤微生物及酶活性的干扰作用[D].哈尔滨:东北林业大学,2014.
[11]杨玉莲.模拟增温对高山森林土壤微生物和酶活性的影响[D].雅安:四川农业大学,2012.
[12]Arno S F,Harrington M G,Fiedler C F,Carlson C E.Restoring fire-dependent ponderosa pine forests in Western Montana.Restoration Management Notes,1995,13:32-36.
[13]Dunn P H,Barro S C,Poth M.Soil moisture affects survival of microorganisms in heated chaparral soil.Soil Biology and Biochemistry,1985,17:143-148.
[14]吕爱锋,田汉勤,刘永强.火干扰与生态系统的碳循环.生态学报,2005,25(10):2734-2743.
[15]韩春兰,邵帅,王秋兵,李甄,孙仲秀,毛伟伟.兴安落叶松林火干扰后土壤有机碳含量变化.生态学报,2015,35(9):3023-3033.
[16]Yang J E,Skogley E O,Schaff B E,Kim J J.A simple spectro-photometric determination of nitrate in water,resin,and soil extracts.Soil Science Society of America Journal,1998,62:1108-1115.
[17]Joergensen R G,Brookes P C.Ninhydrin-reactive N measurements of microbial biomass in 0.5 m K2SO4soil extracts.Soil Biology and Biochemistry 1990,22(8):1023-1027.
[18]DeLuca T H,Keeney D R.Ethanol stabilized chloroform as a fumigant for estimating microbial biomass by reaction with ninhydrin.Soil Biology and Biochemistry,1993,25:1297-1298.
[19]Zibilske L M.Carbon mineralization.Soil Science Society of America,1994:835-863.
[20]SAS Institute.SAS user′s guide.6th ed.Cary,NC:SAS Institute,1995.
[21]Raich JW,Potter CS.Global pat terns of carbon dioxide emissions from soils.Global Biogeochem Cycles,1995,9:23-36
[22]Choromanska U,DeLuca T H.Prescribed fire alters the impact of wildfire on soil biochemical properties in a ponderosa pine forest.Soil Science Society of America Journal,2001,65:232-238.
[23]Pietikinen J,Hiukka R,Fritze H.Does short-term heating of forest humus change its properties as a substrate for microbes?.Soil Biology and Biochemistry,2000,32:277-288.
[24]刘发林,张思玉.火干扰下马尾松林物种多样性和土壤养分特征.西北林学院学报,2009,24(5):36-40.