氮输入对滨海盐沼湿地碳循环关键过程的影响及机制

doi:10.17521/cjpe.2020.0353

摘要/Abstract

摘要：

滨海盐沼湿地是缓解全球变暖的有效蓝色碳汇, 但是近岸海域富营养化导致的大量氮输入对盐沼湿地稳定性和碳汇功能构成严重威胁。潮汐作用下大量氮输入对盐沼湿地植物光合碳输入、植物-土壤碳分配和土壤碳输出等碳循环关键过程产生深刻影响, 进而影响盐沼湿地碳汇功能评估的准确性。该文从植物光合固碳、植物-土壤系统碳分配、土壤有机碳分解、土壤可溶性有机碳释放、盐沼湿地土壤碳库5个方面综述了氮输入对盐沼湿地碳循环关键过程的影响。在此基础上, 针对当前研究的不足, 提出今后的研究中, 需要进一步探究氮输入对盐沼湿地植物光合固碳及碳分配过程的影响、盐沼湿地土壤有机碳分解的微生物机制、盐沼湿地土壤可溶性有机碳产生和横向流动的影响、以及氮类型对盐沼湿地土壤碳库的影响。以期为揭示氮输入对盐沼湿地碳汇形成过程与机制提供基础资料和理论依据, 为评估未来近岸海域水体富营养化影响下滨海盐沼湿地碳库的潜在变化提供新思路。

关键词: 氮输入, 碳循环, 碳分配, 碳汇, 滨海盐沼湿地, 潮汐作用

Abstract:

Coastal salt marshes are an effective blue carbon sink to mitigate climate warming, but their ecosystem stability and carbon sink function are threatened by the large amount of nitrogen input caused by coastal eutrophication. Under the action of regular tides, the high nitrogen content in the coastal waters will have a profound effect on the key processes of carbon cycle such as plant photosynthetic carbon fixation, carbon allocation in plant-soil system, and soil carbon release in the salt marsh. This study reviewed the effects of nitrogen input on plant photosynthetic carbon fixation, carbon allocation in plant-soil system, decomposition of soil organic carbon, formation and release of soil dissolved organic carbon (DOC), and carbon sequestration in the salt marsh. Based on the shortcomings of current research, this review proposed the directions of future research, including the effects of nitrogen input on plant photosynthetic carbon fixation and carbon allocation in plant-soil system, the microbial mechanism of soil organic carbon decomposition, production and lateral exchange of soil DOC, and the potential impact of different forms of nitrogen input on soil carbon sequestration in the salt marsh. Overall, this study aims to improve the understanding of impacts of nitrogen input on the key carbon processes and the mechanisms of carbon sequestration in a salt marsh, and to provide new ideas for assessing the potential changes of carbon pools under the influence of eutrophication of coastal waters in the salt marsh wetlands.

Key words: nitrogen input, carbon cycle, carbon allocation, carbon sink, coastal salt marsh, tidal action

韩广轩, 李隽永, 屈文笛. 氮输入对滨海盐沼湿地碳循环关键过程的影响及机制. 植物生态学报, 2021, 45(4): 321-333. DOI: 10.17521/cjpe.2020.0353

HAN Guang-Xuan, LI Juan-Yong, QU Wen-Di. Effects of nitrogen input on carbon cycle and carbon budget in a coastal salt marsh. Chinese Journal of Plant Ecology, 2021, 45(4): 321-333. DOI: 10.17521/cjpe.2020.0353

导出引用管理器 EndNote|Ris|BibTeX

链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2020.0353

https://www.plant-ecology.com/CN/Y2021/V45/I4/321

图/表 4

图1 潮汐作用下氮(N)输入对盐沼湿地碳(C)循环关键过程的影响。周期性潮汐作用将近岸富营养水体中的氮带入滨海盐沼湿地生态系统中, 改变盐沼湿地土壤营养元素的化学计量关系, 进而对盐沼植物的光合作用及光合产物分配、植物呼吸作用、土壤有机碳分解、可溶性有机碳(DOC)流失等碳循环关键过程产生重要影响。DIC, 可溶性无机碳; POC, 颗粒有机碳。

Fig. 1 Effect of nitrogen (N) input under tidal action on key processes of carbon (C) cycle in a salt marsh. Periodic tides bring N from nearshore eutrophic water into coastal salt marsh ecosystems, changing the stoichiometric relationship of soil nutrient elements in salt marsh wetland. The exogenous N input could have important impacts on the key processes of carbon cycle, such as photosynthesis and respiration of plants, distribution of photosynthetic products, decomposition of soil organic carbon and loss of dissolved organic carbon (DOC). DIC, dissolved inorganic carbon; POC, particulate organic carbon.

图2 氮(N)输入对盐沼湿地土壤有机碳分解的影响(参考Hester et al., 2018 )。微生物过程直接或间接受到氮输入的影响。植物主要吸收铵态氮, 它刺激植物生产力和根际有机质的沉积, 从而刺激根际物质循环, 有利于根际微生物代谢。植物源性碳输入和更高的氮利用性联合刺激微生物异养呼吸, 进而刺激有氧状态下CO2的产生和排放; 而在厌氧状态下, 过量的硝态氮转化为铵态氮, 增加的铵态氮将抑制CH4氧化。

Fig. 2 Effect of nitrogen (N) input on decomposition of soil organic carbon in a salt marsh (adapted from Hester et al., 2018 ). Microbial processes are directly or indirectly affected by N input. Plants mainly absorb NH4+-N, which stimulates plant productivity and the deposition of organic matter from the rhizosphere, thus stimulating the material circulation of rhizosphere and the metabolism of rhizosphere microorganisms. Plant derived carbon input and higher N utilization jointly stimulate microbial heterotrophic respiration, and then stimulate the production and emission of CO2 in aerobic condition. In anaerobic condition, excessive NO3--N is converted into NH4+-N, which will inhibit CH4 oxidation.

图3 氮(N)输入对盐沼湿地可溶性有机碳(DOC)产生和释放的影响。外源氮输入通常伴随着DOC输入, 影响到植被生长, 通过植物残体和微生物生物量改变了土壤和水体中DOC的含量, 从而也会干扰CO2和CH4的排放以及DOC输出。

Fig. 3 Effect of nitrogen (N) input on production and release of dissolved organic carbon (DOC) in a salt marsh. N input is generally accompanied by DOC input, which affects vegetation growth. It alters DOC content in soil and water through plant litter and microbial biomass, thus also interfering with CO2 and CH4 emissions and DOC output.

表1 氮(N)输入对盐沼湿地及其他湿地类型土壤碳库的影响

Table 1 Effect of nitrogen (N) input on carbon sink function of wetland ecosystems

参考文献 103

[1]	Aber J, McDowell W, Nadelhoffer K, Magill A, Berntson G, Kamakea M, McNulty S, Currie W, Rustad L, Fernandez I (1998). Nitrogen saturation in temperate forest ecosystems: hypotheses revisited. BioScience, 48, 921-934. DOI URL
[2]	Alongi DM (2014). Carbon cycling and storage in mangrove forests. Annual Review of Marine Science, 6, 195-219. DOI URL
[3]	Angel R, Claus P, Conrad R (2012). Methanogenic archaea are globally ubiquitous in aerated soils and become active under wet anoxic conditions. The ISME Journal, 6, 847-862. DOI URL
[4]	Anisfeld SC, Hill TD (2012). Fertilization effects on elevation change and belowground carbon balance in a long island sound tidal marsh. Estuaries and Coasts, 35, 201-211. DOI URL
[5]	Armitage AR, Fourqurean JW (2016). Carbon storage in seagrass soils: long-term nutrient history exceeds the effects of near-term nutrient enrichment. Biogeosciences, 13, 313-321. DOI URL
[6]	Bauer JE, Cai WJ, Raymond PA, Bianchi TS, Hopkinson CS, Regnier PAG (2013). The changing carbon cycle of the coastal ocean. Nature, 504, 61-70. DOI URL
[7]	Bolinder MA, Kätterer T, Andrén O, Parent LE (2012). Estimating carbon inputs to soil in forage-based crop rotations and modeling the effects on soil carbon dynamics in a Swedish long-term field experiment. Canadian Journal of Soil Science, 92, 821-833. DOI URL
[8]	Bragazza L, Freeman C, Jones T, Rydin H, Limpens J, Fenner N, Ellis T, Gerdol R, Hájek M, Hájek T, Iacumin P, Kutnar L, Tahvanainen T, Toberman H (2006). Atmospheric nitrogen deposition promotes carbon loss from peat bogs. Proceedings of the National Academy of Sciences of the United States of America, 103, 19386-19389. PMID
[9]	Breitburg D, Levin LA, Oschlies A, Grégoire M, Chavez FP, Conley DJ, Garçon V, Gilbert D, Gutiérrez D, Isensee K, Jacinto GS, Limburg KE, Montes I, Naqvi SWA, Pitcher GC, et al. (2018). Declining oxygen in the global ocean and coastal waters. Science, 359, eaam7240. DOI: 10.1126/science.aam7240. DOI
[10]	Bubier JL, Moore TR, Bledzki LA (2007). Effects of nutrient addition on vegetation and carbon cycling in an ombrotrophic bog. Global Change Biology, 13, 1168-1186. DOI URL
[11]	Chang RY, Li N, Sun XY, Hu ZY, Bai XS, Wang GX (2018). Nitrogen addition reduces dissolved organic carbon leaching in a montane forest. Soil Biology & Biochemistry, 127, 31-38. DOI URL
[12]	Chapin III FS, Matson PA, Mooney HA (2011). Carbon input to terrestrial ecosystems//Chapin III FS, Matson PA, Mooney HA. Principles of Terrestrial Ecosystem Ecology. Springer, New York.
[13]	Chen DM, Lan ZC, Hu SJ, Bai YF (2015a). Effects of nitrogen enrichment on belowground communities in grassland: relative role of soil nitrogen availability vs. soil acidification. Soil Biology & Biochemistry, 89, 99-108. DOI URL
[14]	Chen H, Li D, Gurmesa GA, Yu G, Li L, Zhang W, Fang H, Mo J (2015b). Effects of nitrogen deposition on carbon cycle in terrestrial ecosystems of China: a meta-analysis. Environmental Pollution, 206, 352-360. DOI URL
[15]	Chen XP, Wang GX, Zhang T, Mao TX, Wei D, Song CL, Hu ZY, Huang KW (2017). Effects of warming and nitrogen fertilization on GHG flux in an alpine swamp meadow of a permafrost region. Science of the Total Environment, 601- 602, 1389-1399.
[16]	Chen ZM, Xu YL, He YJ, Zhou XH, Fan JL, Yu HY, Ding WX (2018). Nitrogen fertilization stimulated soil heterotrophic but not autotrophic respiration in cropland soils: a greater role of organic over inorganic fertilizer. Soil Biology & Biochemistry, 116, 253-264. DOI URL
[17]	Chmura GL, Anisfeld SC, Cahoon DR, Lynch JC (2003). Global carbon sequestration in tidal, saline wetland soils. Global Biogeochemical Cycles, 17, 1111. DOI: 10.1029/ 2002GB001917. DOI
[18]	Choi Y, Wang Y (2004). Dynamics of carbon sequestration in a coastal wetland using radiocarbon measurements. Global Biogeochemical Cycles,18, GB4016. DOI: 10.1029/ 2004GB002261. DOI
[19]	Clough BF (1992). Primary productivity and growth of mangrove forests//Robertson AI, Alongi DM. Tropical Mangrove Ecosystems. The American Geophysical Union, Washington D. C. 225-249.
[20]	Cotrufo MF, Wallenstein MD, Boot CM, Denef K, Paul E (2013). The Microbial Efficiency-Matrix Stabilization (MEMS) framework integrates plant litter decomposition with soil organic matter stabilization: Do labile plant inputs form stable soil organic matter? Global Change Biology, 19, 988-995. DOI URL
[21]	Deegan LA, Johnson DS, Warren RS, Peterson BJ, Fleeger JW, Fagherazzi S, Wollheim WM (2012). Coastal eutrophication as a driver of salt marsh loss. Nature, 490, 388-392. DOI URL
[22]	Dise NB (2009). Peatland response to global change. Science, 326, 810-811. DOI URL
[23]	Du E, Terrer C, Pellegrini AFA, Ahlström A, van Lissa CJ, Zhao X, Xia N, Wu X, Jackson RB (2020). Global patterns of terrestrial nitrogen and phosphorus limitation. Nature Geoscience, 13, 221-226. DOI URL
[24]	Duarte CM, Middelburg JJ, Caraco N (2005). Major role of marine vegetation on the oceanic carbon cycle. Biogeosciences, 2, 1-8. DOI URL
[25]	Fang C, Ye JS, Gong Y, Pei J, Yuan Z, Xie C, Zhu Y, Yu Y (2017). Seasonal responses of soil respiration to warming and nitrogen addition in a semi-arid alfalfa-pasture of the Loess Plateau, China. Science of the Total Environment, 590-591, 729-738.
[26]	Fellman JB, D’Amore DV, Hood E, Cunningham P (2017). Vulnerability of wetland soil carbon stocks to climate warming in the perhumid coastal temperate rainforest. Biogeochemistry, 133, 165-179. DOI URL
[27]	Fernández-Martínez M, Vicca S, Janssens IA, Sardans J, Luyssaert S, Campioli M, Chapin III FS, Ciais P, Malhi Y, Obersteiner M, Papale D, Piao SL, Reichstein M, Rodà F, Peñuelas J (2014). Nutrient availability as the key regulator of global forest carbon balance. Nature Climate Change, 4, 471-476. DOI URL
[28]	Gacia E, Duarte CM, Middelburg JJ (2002). Carbon and nutrient deposition in a Mediterranean seagrass (Posidonia oceanica) meadow. Limnology and Oceanography, 47, 23-32. DOI URL
[29]	Graham SA, Mendelssohn IA (2016). Contrasting effects of nutrient enrichment on below-ground biomass in coastal wetlands. Journal of Ecology, 104, 249-260. DOI URL
[30]	Guerrieri R, Mencuccini M, Sheppard LJ, Saurer M, Perks MP, Levy P, Sutton MA, Borghetti M, Grace J (2011). The legacy of enhanced N and S deposition as revealed by the combined analysis of δ ¹³C, δ ¹⁸O and δ ¹⁵N in tree rings. Global Change Biology, 17, 1946-1962. DOI URL
[31]	Han G, Xing Q, Yu J, Luo Y, Li D, Yang L, Wang G, Mao P, Xie B, Mikle N (2014). Agricultural reclamation effects on ecosystem CO₂ exchange of a coastal wetland in the Yellow River Delta. Agriculture Ecosystems & Environment, 196, 187-198. DOI URL
[32]	Han GX ( 2017). Effect of tidal action and drying-wetting cycles on carbon exchange in a salt marsh: progress and prospects. Acta Ecologica Sinica, 37, 8170-8178.
	[ 韩广轩 ( 2017). 潮汐作用和干湿交替对盐沼湿地碳交换的影响机制研究进展. 生态学报, 37, 8170-8178.]
[33]	Harpole WS, Sullivan LL, Lind EM, Firn J, Adler PB, Borer ET, Chase J, Fay PA, Hautier Y, Hillebrand H, MacDougall AS, Seabloom EW, Williams R, Bakker JD, Cadotte MW, et al. (2016). Addition of multiple limiting resources reduces grassland diversity. Nature, 537, 93-96. DOI URL
[34]	Hayes MA, Jesse A, Tabet B, Reef R, Keuskamp JA, Lovelock CE (2017). The contrasting effects of nutrient enrichment on growth, biomass allocation and decomposition of plant tissue in coastal wetlands. Plant and Soil, 416,193-204. DOI URL
[35]	Herbert ER, Schubauer-Berigan JP, Craft CB (2020). Effects of 10 yr of nitrogen and phosphorus fertilization on carbon and nutrient cycling in a tidal freshwater marsh. Limnology and Oceanography, 65, 1669-1687. DOI URL
[36]	Hester ER, Harpenslager SF, van Diggelen JMH, Lamers LL, Jetten MSM, Lüke C, Lücker S, Welte CU (2018). Linking nitrogen load to the structure and function of wetland soil and rhizosphere microbial communities. mSystems, 3, e00214-17. DOI: 10.1128/mSystems.00214-17. DOI
[37]	Högberg MN, Briones MJI, Keel SG, Metcalfe DB, Campbell C, Midwood AJ, Thornton B, Hurry V, Linder S, Näsholm T, Högberg P (2010). Quantification of effects of season and nitrogen supply on tree below-ground carbon transfer to ectomycorrhizal fungi and other soil organisms in a boreal pine forest. New Phytologist, 187, 485-493. DOI URL
[38]	Hu Y, Wang L, Fu X, Yan J, Wu J, Tsang Y, Le Y, Sun Y (2016). Salinity and nutrient contents of tidal water affects soil respiration and carbon sequestration of high and low tidal flats of Jiuduansha wetlands in different ways. Science of the Total Environment, 565, 637-648. DOI URL
[39]	Huxham M, Langat J, Tamooh F, Kennedy H, Mencuccini M, Skov MW, Kairo J (2010). Decomposition of mangrove roots: effects of location, nutrients, species identity and mix in a Kenyan forest. Estuarine Coastal and Shelf Science, 88, 135-142. DOI URL
[40]	Iversen CM, Bridgham SD, Kellogg LE (2010). Scaling plant nitrogen use and uptake efficiencies in response to nutrient addition in peatlands. Ecology, 91, 693-707. DOI URL
[41]	Janssens IA, Dieleman W, Luyssaert S, Subke JA, Reichstein M, Ceulemans R, Ciais P, Dolman AJ, Grace J, Matteucci G, Papale D, Piao SL, Schulze ED, Tang J, Law BE (2010). Reduction of forest soil respiration in response to nitrogen deposition. Nature Geoscience, 3, 315-322. DOI URL
[42]	Jones DL, Kielland K (2012). Amino acid, peptide and protein mineralization dynamics in a taiga forest soil. Soil Biology & Biochemistry, 55, 60-69. DOI URL
[43]	Juutinen S, Bubier JL, Moore TR (2010). Responses of vegetation and ecosystem CO₂ exchange to 9 years of nutrient addition at Mer Bleue bog. Ecosystems, 13, 874-887. DOI URL
[44]	Keuskamp JA, Feller IC, Laanbroek HJ, Verhoeven JTA, Hefting MM (2015). Short- and long-term effects of nutrient enrichment on microbial exoenzyme activity in mangrove peat. Soil Biology & Biochemistry, 81, 38-47. DOI URL
[45]	Kiba T, Krapp A (2016). Plant nitrogen acquisition under low availability: regulation of uptake and root architecture. Plant and Cell Physiology, 57, 707-714. DOI URL
[46]	Kim J, Chaudhary DR, Kang H (2020). Nitrogen addition differently alters GHGs production and soil microbial community of tidal salt marsh soil depending on the types of halophyte. Applied Soil Ecology, 150, 103440. DOI: 10.1016/j.apsoil.2019.103440. DOI URL
[47]	Kirwan ML, Patrick Megonigal J (2013). Tidal wetland stability in the face of human impacts and sea-level rise. Nature, 504, 53-60. DOI URL
[48]	Kivimäki SK, Sheppard LJ, Leith ID, Grace J (2013). Long-term enhanced nitrogen deposition increases ecosystem respiration and carbon loss from a Sphagnum bog in the Scottish Borders. Environmental and Experimental Botany, 90, 53-61. DOI URL
[49]	Larmola T, Bubier JL, Kobyljanec C, Basiliko N, Juutinen S, Humphreys E, Preston M, Moore TR (2013). Vegetation feedbacks of nutrient addition lead to a weaker carbon sink in an ombrotrophic bog. Global Change Biology, 19, 3729-3739. DOI PMID
[50]	Li W, Zhang H, Huang G, Liu R, Zhao C, McDowell NG (2020). Effects of nitrogen enrichment on tree carbon allocation: a global synthesis. Global Ecology and Biogeography, 29, 573-589. DOI URL
[51]	Liu J, Wu N, Wang H, Sun J, Peng B, Jiang P, Bai E (2016). Nitrogen addition affects chemical compositions of plant tissues, litter and soil organic matter. Ecology, 97, 1796-1806. DOI URL
[52]	Ma TT, Li XW, Bai JH, Ding SY, Zhou FW, Cui BS (2019). Four decadesʼ dynamics of coastal blue carbon storage driven by land use/land cover transformation under natural and anthropogenic processes in the Yellow River Delta, China. Science of the Total Environment, 655, 741-750. DOI URL
[53]	Mack MC, Schuur EAG, Syndonia Bret-Harte M, Shaver GR, Chapin III FS (2004). Ecosystem carbon storage in arctic tundra reduced by long-term nutrient fertilization. Nature, 431, 440-443. DOI URL
[54]	Macreadie PI, Anton A, Raven JA, Beaumont N, Connolly RM, Friess DA, Kelleway JJ, Kennedy H, Kuwae T, Lavery PS, Lovelock CE, Smale DA, Apostolaki ET, Atwood TB, Baldock J, et al. (2019). The future of Blue Carbon science. Nature Communications, 10, 3998. DOI: 10.1038/ s41467-019-11693-w. DOI PMID
[55]	Majdi H, Öhrvik J (2004). Interactive effects of soil warming and fertilization on root production, mortality, and longevity in a Norway spruce stand in Northern Sweden. Global Change Biology, 10, 182-188. DOI URL
[56]	Majidzadeh H, Uzun H, Ruecker A, Miller D, Vernon J, Zhang HY, Bao SW, Tsui MTK, Karanfil T, Chow AT (2017). Extreme flooding mobilized dissolved organic matter from coastal forested wetlands. Biogeochemistry, 136, 293-309. DOI URL
[57]	Manzoni S, Taylor P, Richter A, Porporato A, Ågren GI (2012). Environmental and stoichiometric controls on microbial carbon-use efficiency in soils. New Phytologist, 196, 79-91. DOI URL
[58]	Mao Q, Lu X, Mo H, Gundersen P, Mo J (2018). Effects of simulated N deposition on foliar nutrient status, N metabolism and photosynthetic capacity of three dominant understory plant species in a mature tropical forest. Science of the Total Environment, 610-611, 555-562.
[59]	McLeod E, Chmura GL, Bouillon S, Salm R, Björk M, Duarte CM, Lovelock CE, Schlesinger WH, Silliman BR (2011). A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO₂. Frontiers in Ecology and the Environment, 9, 552-560. DOI URL
[60]	Mills RTE, Tipping E, Bryant CL, Emmett BA (2014). Long-term organic carbon turnover rates in natural and semi-natural topsoils. Biogeochemistry, 118, 257-272. DOI URL
[61]	Min K, Kang H, Lee D (2011). Effects of ammonium and nitrate additions on carbon mineralization in wetland soils. Soil Biology & Biochemistry, 43, 2461-2469. DOI URL
[62]	Mitsch WJ, Gosselink JG (2011). Wetlands.4th ed. John Wiley & Sons, Hobgen, USA.
[63]	Mou XJ, Sun ZG, Wang LL, Wang CY (2011). Nitrogen cycle of a typical Suaeda salsa marsh ecosystem in the Yellow River estuary. Journal of Environmental Sciences, 23, 958-967. DOI URL
[64]	Pardo LH, Fenn ME, Goodale CL, Geiser LH, Driscoll CT, Allen EB, Baron JS, Bobbink R, Bowman WD, Clark CM, Emmett B, Gilliam FS, Greaver TL, Hall SJ, Lilleskov EA, et al. (2011). Effects of nitrogen deposition and empirical nitrogen critical loads for ecoregions of the United States. Ecological Applications, 21, 3049-3082. DOI URL
[65]	Pastore MA, Megonigal JP, Langley JA (2017). Elevated CO₂ and nitrogen addition accelerate net carbon gain in a brackish marsh. Biogeochemistry, 133, 73-87. DOI URL
[66]	Pausch J, Kuzyakov Y (2018). Carbon input by roots into the soil: quantification of rhizodeposition from root to ecosystem scale. Global Change Biology, 24, 1-12. DOI URL
[67]	Peng Y, Peng Z, Zeng X, Houx III JH (2019). Effects of nitrogen- phosphorus imbalance on plant biomass production: a global perspective. Plant and Soil, 436, 245-252. DOI URL
[68]	Pennings SC (2012). Ecology: the big picture of marsh loss. Nature, 490, 352-353. DOI URL
[69]	Preston DL, Sokol ER, Hell K, McKnight DM, Johnson PTJ (2020). Experimental effects of elevated temperature and nitrogen deposition on high-elevation aquatic communities. Aquatic Sciences, 82, 7. DOI: 10.1007/s00027-019-0678-4. DOI
[70]	Qu W, Han G, Eller F, Xie B, Wang J, Wu H, Li J, Zhao M (2020). Nitrogen input in different chemical forms and levels stimulates soil organic carbon decomposition in a coastal wetland. Catena, 194, 104672. DOI: 10.1016/ j.catena.2020.104672. DOI URL
[71]	Radabaugh KR, Moyer RP, Chappel AR, Powell CE, Bociu I, Clark BC, Smoak JM (2018). Coastal blue carbon assessment of mangroves, salt marshes, and salt barrens in Tampa Bay, Florida, USA. Estuaries and Coasts, 41, 1496-1510. DOI URL
[72]	Romero LM, Smith III TJ, Fourqurean JW (2005). Changes in mass and nutrient content of wood during decomposition in a South Florida mangrove forest. Journal of Ecology, 93, 618-631. DOI URL
[73]	Rousk J, Brookes PC, Bååth E (2010). Investigating the mechanisms for the opposing pH relationships of fungal and bacterial growth in soil. Soil Biology & Biochemistry, 42, 926-934. DOI URL
[74]	Shen H, Dong S, Li S, Xiao J, Han Y, Yang M, Zhang J, Gao X, Xu Y, Li Y, Zhi Y, Liu S, Dong Q, Zhou H, Yeomans JC (2019). Effects of simulated N deposition on photosynthesis and productivity of key plants from different functional groups of alpine meadow on Qinghai-Tibetan Plateau. Environmental Pollution, 251, 731-737. DOI
[75]	Sherman RE, Fahey TJ, Martinez P (2003). Spatial patterns of biomass and aboveground net primary productivity in a mangrove ecosystem in the Dominican Republic. Ecosystems, 6, 384-398. DOI URL
[76]	Shipley B, Meziane D (2002). The balanced-growth hypothesis and the allometry of leaf and root biomass allocation. Functional Ecology, 16, 326-331. DOI URL
[77]	Sinsabaugh RL, Belnap J, Rudgers J, Kuske CR, Martinez N, Sandquist D (2015). Soil microbial responses to nitrogen addition in arid ecosystems. Frontiers in Microbiology, 6, 819. DOI: 10.3389/fmicb.2015.00819. DOI PMID
[78]	Sinsabaugh RL, Moorhead DL (1994). Resource allocation to extracellular enzyme production: a model for nitrogen and phosphorus control of litter decomposition. Soil Biology & Biochemistry, 26, 1305-1311. DOI URL
[79]	Smith MD, La Pierre KJ, Collins SL, Knapp AK, Gross KL, Barrett JE, Frey SD, Gough L, Miller RJ, Morris JT, Rustad LE, Yarie J (2015). Global environmental change and the nature of aboveground net primary productivity responses: insights from long-term experiments. Oecologia, 177, 935-947. DOI URL
[80]	Song CC, Liu DY, Yang GS, Song YY, Mao R (2011). Effect of nitrogen addition on decomposition of Calamagrostis angustifolia litters from freshwater marshes of Northeast China. Ecological Engineering, 37, 1578-1582. DOI URL
[81]	Song CC, Wang LL, Tian HQ, Liu DY, Lu CQ, Xu XF, Zhang LH, Yang GS, Wan ZM (2013). Effect of continued nitrogen enrichment on greenhouse gas emissions from a wetland ecosystem in the Sanjiang Plain, Northeast China: a 5 year nitrogen addition experiment. Journal of Geophysical Research, 118, 741-751.
[82]	Song MH, Jiang J, Cao GM, Xu XL (2010). Effects of temperature, glucose and inorganic nitrogen inputs on carbon mineralization in a Tibetan alpine meadow soil. European Journal of Soil Biology, 46, 375-380. DOI URL
[83]	Strokal M, Yang H, Zhang Y, Kroeze C, Li L, Luan S, Wang H, Yang S, Zhang Y (2014). Increasing eutrophication in the coastal seas of China from 1970 to 2050. Marine Pollution Bulletin, 85, 123-140. DOI PMID
[84]	Tao BX, Liu CY, Zhang BH, Dong J (2018). Effects of inorganic and organic nitrogen additions on CO₂ emissions in the coastal wetlands of the Yellow River Delta, China. Atmospheric Environment, 185, 159-167. DOI URL
[85]	Tipping E, Rowe EC, Evans CD, Mills RTE, Emmett BA, Chaplow JS, Hall JR (2012). N¹⁴C: a plant-soil nitrogen and carbon cycling model to simulate terrestrial ecosystem responses to atmospheric nitrogen deposition. Ecological Modelling, 247, 11-26. DOI URL
[86]	van Wijnen HJ, Bakker JP (1999). Nitrogen and phosphorus limitation in a coastal barrier salt marsh: the implications for vegetation succession. Journal of Ecology, 87, 265-272. DOI URL
[87]	Vitousek PM, Hättenschwiler S, Olander L, Allison S (2002). Nitrogen and nature. AMBIO: A Journal of the Human Environment, 31, 97-101. PMID
[88]	Vivanco L, Irvine IC, Martiny JBH (2015). Nonlinear responses in salt marsh functioning to increased nitrogen addition. Ecology, 96, 936-947. PMID
[89]	Wang B, Xin M, Wei Q, Xie L (2018). A historical overview of coastal eutrophication in the China Seas. Marine Pollution Bulletin, 136, 394-400. DOI URL
[90]	Wang H, Yu L, Zhang Z, Liu W, Chen L, Cao G, Yue H, Zhou J, Yang Y, Tang Y, He J (2017). Molecular mechanisms of water table lowering and nitrogen deposition in affecting greenhouse gas emissions from a Tibetan alpine wetland. Global Change Biology, 23, 815-829. DOI PMID
[91]	Wang J, Gao Y, Zhang Y, Yang J, Smith MD, Knapp AK, Eissenstat DM, Han X (2019). Asymmetry in above- and belowground productivity responses to N addition in a semi-arid temperate steppe. Global Change Biology, 25, 2958-2969. DOI URL
[92]	Wang Q, Wang S, He T, Liu L, Wu J (2014). Response of organic carbon mineralization and microbial community to leaf litter and nutrient additions in subtropical forest soils. Soil Biology & Biochemistry, 71, 13-20. DOI URL
[93]	Wang TT, Zhu ZK, Zhu HH, Tang ZZ, Pang J, Li BZ, Su YR, Ge TD, Wu JS ( 2017). Input and distribution of photosynthesized carbon in soil-rice system affected by water management and nitrogen fertilization. Environmental Science, 38, 1227-1234.
	[ 王婷婷, 祝贞科, 朱捍华, 汤珍珠, 庞静, 李宝珍, 苏以荣, 葛体达, 吴金水 ( 2017). 施氮和水分管理对光合碳在土壤-水稻系统间分配的量化研究. 环境科学, 38, 1227-1234.]
[94]	Wei C, Yu Q, Bai E, Lü X, Li Q, Xia J, Kardol P, Liang W, Wang Z, Han X (2013). Nitrogen deposition weakens plant-microbe interactions in grassland ecosystems. Global Change Biology, 19, 3688-3697. DOI URL
[95]	Wendel S, Moore T, Bubier J, Blodau C (2011). Experimental nitrogen, phosphorus, and potassium deposition decreases summer soil temperatures, water contents, and soil CO₂ concentrations in a northern bog. Biogeosciences, 8, 585-595. DOI URL
[96]	Wu Y, Blodau C, Moore TR, Bubier J, Juutinen S, Larmola T (2015). Effects of experimental nitrogen deposition on peatland carbon pools and fluxes: a modelling analysis. Biogeosciences, 12, 79-101. DOI URL
[97]	Xiao LL, Xie BH, Liu JC, Zhang HX, Han GX, Wang OM, Liu FH (2017). Stimulation of long-term ammonium nitrogen deposition on methanogenesis by Methanocellaceae in a coastal wetland. Science of the Total Environment, 595, 337-343. DOI URL
[98]	Xiao ML, Zang HD, Liu SL, Ye RZ, Zhu ZK, Su YR, Wu JS, Ge TD (2019). Nitrogen fertilization alters the distribution and fates of photosynthesized carbon in rice-soil systems: a¹³C-CO₂ pulse labeling study. Plant and Soil, 445, 101-112. DOI URL
[99]	Xu X, Liu H, Liu YZ, Zhou CH, Pan LH, Fang CM, Nie M, Li B (2020). Human eutrophication drives biogeographic salt marsh productivity patterns in China. Ecological Applications, 30, e02045. DOI: 10.1002/eap.2045. DOI
[100]	Xu X, Schimel JP, Thornton PE, Song X, Yuan F, Goswami S (2014). Substrate and environmental controls on microbial assimilation of soil organic carbon: a framework for Earth system models. Ecology Letters, 17, 547-555. DOI URL
[101]	Yang K, Zhu JJ, Gu JC, Xu S, Yu LZ, Wang ZQ (2018). Effects of continuous nitrogen addition on microbial properties and soil organic matter in a Larix gmeliniiplantation in China. Journal of Forestry Research, 29, 85-92. DOI URL
[102]	Yao RJ, Yang JS, Wang XP, Xie WP, Zheng FL, Li HQ, Tang C, Zhu H (2021). Response of soil characteristics and bacterial communities to nitrogen fertilization gradients in a coastal salt-affected agroecosystem. Land Degradation & Development, 32, 338-353. DOI URL
[103]	Zhou ZH, Wang CK, Zheng MH, Jiang LF, Luo YQ (2017). Patterns and mechanisms of responses by soil microbial communities to nitrogen addition. Soil Biology & Biochemistry, 115, 433-441. DOI URL