氮磷富集对森林土壤碳截存的影响研究进展
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摘要
大气氮磷沉降增加森林土壤养分的可利用性,改变底物的化学质量、土壤微生物组成和功能,进而影响土壤有机质的储量与稳定性。然而,现有研究主要集中在氮素富集对自然森林生态系统碳截存的影响,有关磷富集以及氮磷交互对人工林土壤有机碳(SOC)截存的影响及其微生物学机制尚不清楚。本文综述了氮磷富集对森林土壤碳转化和净交换通量、土壤有机质(SOM)的激发效应、SOM组成与稳定性以及介导碳转化功能微生物群落的影响,并指出各个研究环节的不足,包括:(1)森林土壤碳通量及其组分对氮磷富集的非线性响应方程及临界阈值尚未确定;(2)氮磷富集对森林SOM激发效应的影响程度与潜在机制知之甚少;(3)SOM的物理-化学协同稳定机制研究不够深入;(4)土壤活性微生物群落组成、SOM化学结构与SOC累积之间的耦联关系尚不清晰。据此,指出未来研究重点与研究思路:基于多水平氮磷添加控制试验和~(13)C标记培养实验,利用原位监测、土壤化学(~(13)C-NMR和Py-GC/MS)、宏基因组测序的分子生物学方法,重点研究氮磷添加及其交互作用对人工林土壤碳排放与流失通量、微生物激发效应、SOM组成与化学稳定性以及功能微生物群落组成的影响,确定土壤碳输出通量对氮磷添加的非线性响应方程与氮沉降临界负荷,阐明分解微生物群落组成与土壤碳转化及稳定性的耦联关系,揭示氮磷交互影响人工林土壤碳积累与损耗的微生物学机制。研究结果有助于控制森林尤其是人工林土壤碳损失,有效降低陆地"氮促碳汇"评估的不确定性,并可为森林生态系统应对全球变化提供科学依据。
Atmospheric nitrogen(N) and phosphorus(P) deposition increases soil nutrients available for plants, change chemical quality of the substrates, as well as composition and function of the soil microorganisms, thereby affecting storage and stability of the soil organic matter(SOM) in forest soils.However, the studies reported in the literature focused mainly on effects of N enrichment on carbon(C)sequestration in natural forest ecosystems, with little eyesight on effects of P enrichment and interaction of N and P on soil organic carbon(SOC) sequestration of in artificial forests as well as their microbiological mechanisms. In this paper, a review is presented of effects of N and P enrichment on C transformation and net C exchange fluxes, priming effect of SOM, chemical composition and stability of SOM, and composition and functions of microbial communities mediating C turunover in forest soils; moreover, the authors also shed light on deficiencies in the present researches, as follows.(1) Nonlinear response equations of soil C flux and its components in response to N and P enrichment in forest soils as well as their critical thresholds have not yet been determined;(2) Little is known about effects of N and P enrichment on priming effect of SOM in forest ecosystems and microbial mechanisms;(3) In-depth researches on mechanism of the physicochemical synergic stabilization of SOM under N and P enrichment are far from sufficient; and(4) It is still unclear how composition of soil active microbial community and SOM chemical structure is related to SOC accumulation. Therefore, the authors hold that future researches should foucs on the following aspects: Based on the established multi-level N and P addition and ~(13)C-labeled incubation experiments,effects of N and P addition and their interaction on soil C emission and loss fluxes, microbial priming effect, composition and chemical stability of SOM, and functional microbial community composition are to be determined using the techniques of in-situ monitoring, soil chemistry(~(13)C-NMR and Py-GC/MS),and macrogenomics of molecular biology, etc. Besides, more efforts should be laid on(1) defining the nonlinear equations for responses of soil C emission and loss to N and P addition as well as critical loads of atmospheric N and P depositions;(2) elucidating coupling relationships between composition of the soil decomposing microbial community and SOC transformation and stability; and(3) exposing microbial mechanisms responsible for the effects of N and P interaction on soil C accumulation and depletion in forest ecosystems, especially in subtropical plantations. All the findings in this review will help control C losses from forest soils, reduce uncertainties in assessing "N promoted C sink" in terrestrial ecosystems, and hence provide a scientific basis for subtropical plantations or forest ecosystems to deal with global change.
Atmospheric nitrogen(N) and phosphorus(P) deposition increases soil nutrients available for plants, change chemical quality of the substrates, as well as composition and function of the soil microorganisms, thereby affecting storage and stability of the soil organic matter(SOM) in forest soils.However, the studies reported in the literature focused mainly on effects of N enrichment on carbon(C)sequestration in natural forest ecosystems, with little eyesight on effects of P enrichment and interaction of N and P on soil organic carbon(SOC) sequestration of in artificial forests as well as their microbiological mechanisms. In this paper, a review is presented of effects of N and P enrichment on C transformation and net C exchange fluxes, priming effect of SOM, chemical composition and stability of SOM, and composition and functions of microbial communities mediating C turunover in forest soils; moreover, the authors also shed light on deficiencies in the present researches, as follows.(1) Nonlinear response equations of soil C flux and its components in response to N and P enrichment in forest soils as well as their critical thresholds have not yet been determined;(2) Little is known about effects of N and P enrichment on priming effect of SOM in forest ecosystems and microbial mechanisms;(3) In-depth researches on mechanism of the physicochemical synergic stabilization of SOM under N and P enrichment are far from sufficient; and(4) It is still unclear how composition of soil active microbial community and SOM chemical structure is related to SOC accumulation. Therefore, the authors hold that future researches should foucs on the following aspects: Based on the established multi-level N and P addition and ~(13)C-labeled incubation experiments,effects of N and P addition and their interaction on soil C emission and loss fluxes, microbial priming effect, composition and chemical stability of SOM, and functional microbial community composition are to be determined using the techniques of in-situ monitoring, soil chemistry(~(13)C-NMR and Py-GC/MS),and macrogenomics of molecular biology, etc. Besides, more efforts should be laid on(1) defining the nonlinear equations for responses of soil C emission and loss to N and P addition as well as critical loads of atmospheric N and P depositions;(2) elucidating coupling relationships between composition of the soil decomposing microbial community and SOC transformation and stability; and(3) exposing microbial mechanisms responsible for the effects of N and P interaction on soil C accumulation and depletion in forest ecosystems, especially in subtropical plantations. All the findings in this review will help control C losses from forest soils, reduce uncertainties in assessing "N promoted C sink" in terrestrial ecosystems, and hence provide a scientific basis for subtropical plantations or forest ecosystems to deal with global change.
引文
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[2]Magnani F,Mencuccini M,Borghetti M,et al.The human footprint in the carbon cycle of temperate and boreal forests.Nature,2007,447(7146):849-851
[3]de Vries W,Solberg S,Dobber tin M,et al.Ecologically implausible carbon response?Nature,2008,451(7180):E1-E3
[4]de Vries W I M,Reinds G J,Gundersen P E R,et al.The impact of nitrogen deposition on carbon sequestration in European forests and forest soils.Global Change Biology,2006,12(7):1151-1173
[5]Janssens I A,Dieleman W,Luyssaert S,et al.Reduction of forest soil respiration in response to nitrogen deposition.Nature Geoscience,2010,3(5):315-322
[6]Ratliff T J,Fisk M C.Phosphatase activity is related to N availability but not P availability across hardwood forests in the northeastern United States.Soil Biology&Biochemistry,2016,94:61-69
[7]Matson P A,McDowell W H,Townsend A R,et al.The globalization of N deposition:Ecosystem consequences in tropical environments.Biogeochemistry,1999,46(1/3):67-83
[8]Penuelas J,Sardans J,Rivas‐ubach A,et al.The human-induced imbalance between C,N and P in Earth’s life system.Global Change Biology,2012,18(1):3-6
[9]Zhu J,Wang Q,He N,et al.Imbalanced atmospheric nitrogen and phosphorus depositions in China Impl icat ions for nut r ient l imi tat ion.Journal of Geophysical Research-Biogeosciences,2016,121(6):1605-1616
[10]Winjum J K,Schroeder P E.Forest plantations of the world:Their extent,ecological attributes,and carbon storage.Agricultural and Forest Meteorology,1997,84(1/2):153-167
[11]Fang J,Chen A,Peng C,et al.Changes in forest biomass carbon storage in China between 1949 and1998.Science,2001,292(5525):2320-2322
[12]Piao S,Fang J,Ciais P,et al.The carbon balance of terrestrial ecosystems in China.Nature,2009,458(7241):1009-1013
[13]McDowell W H,Magill A H,Aitkenhead-Peterson J A,et al.Effects of chronic nitrogen amendment on dissolved organic matter and inorganic nitrogen in soil solution.Forest Ecology and Management,2004,196(1):29-41
[14]Wang Y,Cheng S,Fang H,et al.Contrasting effects of ammonium and nitrate inputs on soil CO2 emission in a subtropical coniferous plantation of southern China.Biology and Fertility of Soils,2015,51(7):815-825
[15]Mo J,Zhang W E I,Zhu W,et al.Nitrogen addition reduces soil respiration in a mature tropical forest in southern China.Global Change Biology,2008,14(2):403-412
[16]Zeng W,Wang W.Combination of nitrogen and phosphorus fertilization enhance ecosystem carbon sequestration in a nitrogen-limited temperate plantation of Northern China.Forest Ecology and Management,2015,341:59-66
[17]Kang H Z,Fahey T J,Bae K,et al.Response of forest soil respiration to nutrient addition depends on site fertility.Biogeochemistry,2016,127(1):113-124
[18]Wang Q K,Zhang W D,Sun T,et al.N and Pfertilization reduced soil autotrophic and heterotrophic respiration in a young Cunninghamia lanceolata forest.Agricultural and Forest Meteorology,2017,232:66-73
[19]Jones D L,Hughes L T,Murphy D V,et al.Dissolved organic carbon and nitrogen dynamics in temperate coniferous forest plantations.European Journal of Soil Science,2008,59(6):1038-1048
[20]Rowe E C,Tipping E,Posch M,et al.Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter.Environmental Pollution,2014,184(1):271-282
[21]Lu X,Gilliam F S,Yu G,et al.Long-term nitrogen addition decreases carbon leaching in a nitrogen-rich forest ecosystem.Biogeosciences,2013,10(6):3931-3941
[22]DeForest J L,Zak D R,Pregitzer K S,et al.Atmospheric nitrate deposition and enhanced dissolved organic carbon leaching.Soil Science Society of America Journal,2005,69(4):1233-1237
[23]F a n g H,Cheng S,Yu G,et al.Experimental nitrogen deposition alters the quantity and quality of soil dissolved organic carbon in an alpine meadow on the Qinghai-Tibetan Plateau.Applied Soil Ecology,2014,81:1-11
[24]Cleveland C C,Reed S C,Townsend A R.Nutrient regulat ion of organic mat ter decomposit ion in a tropical rain forest.Ecology,2006,87(2):492-503
[25]Mori T,Wachrinrat C,Staporn D,et al.Contrastive effects of inorganic phosphorus addition on soil microbial respiration and microbial biomass in tropical monoculture tree plantation soils in Thailand.Agriculture and Natural Resources,2016,50(5):327-330
[26]Gomez-Casanovas N,Hudiburg T W,Bernacchi C J,et al.Nitrogen deposition and greenhouse gas emissions from grasslands:Uncertainties and future directions.Global Change Biology,2016,22(4):1348-1360
[27]Kuzyakov Y,Friedel J K,Stahr K.Review of mechanisms and quantification of priming effects.Soil Biology&Biochemistry,2000,32(11):1485-1498
[28]Cheng W,Parton W J,Gonzalez-Meler M A,et al.Synthesis and modeling perspectives of rhizosphere priming.New Phytologist,2014,201(1):31-44
[29]Zimmerman A R,Gao B,Ahn M Y.Positive and negative carbon mineralization priming effects among a variety of biochar-amended soils.Soil Biology&Biochemistry,2011,43(6):1169-1179
[30]Meyer N,Welp G,Bornemann L,et al.Microbial nitrogen mining affects spatio-temporal patterns of substrate-induced respiration during seven years of bare fallow.Soil Biology&Biochemistry,2017,104:175-184
[31]Hamer U,Marschner B.Priming effects in different soil types induced by fructose,alanine,oxalic acid and catechol additions.Soil Biology&Biochemistry,2005,37(3):445-454
[32]Craine J M,Morrow C,Fierer N.Microbial nitrogen limitation increases decomposition.Ecology,2007,88(8):2105-2113
[33]Burns R G,DeForest J L,Marxsen J,et al.Soil enzymes i n a chan g ing en v ironmen t:Curren t knowledge and future directions.Soil Biology&Biochemistry,2013,58:216-234
[34]Phillips R P,Finzi A C,Bernhardt E S.Enhanced root exudation induces microbial feedbacks to N cycling in a pine forest under long-term CO2 fumigation.Ecology Letters,2011,14(2):187-194
[35]Dijkstra F A,Carrillo Y,Pendall E,et al.Rhizosphere priming:A nutrient perspective.The Microbial Regulation of Global Biogeochemical Cycles,2014,4(1):216
[36]Nottingham A T,Turner B L,Stott A W,et al.Nitrogen and phosphorus constrain labile and stable carbon turnover in lowland tropical forest soils.Soil Biology&Biochemistry,2015,80:26-33
[37]Poeplau C,Bolinder M A,Kirchmann H,et al.Phosphorus fertilisation under nitrogen limitation can deplete soil carbon stocks:Evidence from Swedish meta-replicated long-term field experiments.Biogeosciences,2016,13(19):1119-1127
[38]Roscoe R,Buurman P.Tillage effects on soil organic matter in density fractions of a Cerrado Oxisol.Soil and Tillage Research,2003,70(2):107-119
[39]Six J,Conant R T,Paul E A,et al.Stabilization mechanisms of soil organic matter:Implications for C-saturation of soils.Plant and Soil,2002,241(2):155-176
[40]Hagedorn F,Spinnler D,Siegwolf R.Increased Ndeposition retards mineralization of old soil organic matter.Soil Biology&Biochemistry,2003,35(12):1683-1692
[41]Zhong X L,Li J T,Li X J,et al.Physical protection by soil aggregates stabilizes soil organic carbon under simulated N deposition in a subtropical forest of China.Geoderma,2017,285:323-332
[42]Malhi S S,Harapiak J T,Nyborg M,et al.Total and light fraction organic C in a thin Black Chernozemic grassland soil as affected by 27 annual applications of six rates of fertilizer N.Nutrient Cycling in Agroecosystems,2003,66(1):33-41
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