早春和夏季氮磷添加对内蒙古典型草原退化群落碳交换的影响

doi:10.17521/cjpe.2020.0277

摘要/Abstract

摘要：

过度放牧导致的养分“入不敷出”是我国天然草地大面积退化的主要原因之一, 而草地退化又显著影响了草原生态系统的固碳功能。能否通过补充土壤养分来恢复退化草地的固碳功能, 迄今相关研究较少。净生态系统碳交换(NEE)、生态系统呼吸(ER)和生态系统总初级生产力(GEP)是表征生态系统碳循环的重要指标。氮(N)和磷(P)是中国典型草原的主要限制性养分元素, 而草地退化进一步加剧了养分的限制。在退化草地上添加氮磷对碳循环的上述过程(NEE、ER和GEP)有何影响, 以及两种养分之间是否存在互作, 目前尚不清楚。为此, 该研究以内蒙古典型草原的退化草地为研究对象, 选择早春融雪期(4月)和夏季生长期(7月)两个时间节点, 设置不施肥(CK)、N添加(10.5 g·m^-2·a^-1, NH₄NO₃)、P添加(7 g·m^-2·a^-1, KH₂PO₄)和N、P共同添加((10.5 g N + 7 g P)·m^-2·a^-1) 4个养分处理, 探究早春和夏季氮磷添加对内蒙古典型草原退化群落碳交换的影响及其互作机制。结果表明: 1)在早春和夏季两个时期, 单独添加N或P对生态系统碳交换过程的影响均未达到显著水平, 而氮磷共同添加可显著提高NEE和GEP。2)早春(4月份)氮磷共同添加对NEE、ER和GEP的互作机制表现为正协同效应, 而夏季(7月份)氮磷共同添加对NEE、ER和GEP的互作机制表现为加性效应。为了恢复退化的典型草原的固碳功能, 氮磷共同添加比单一元素添加效果好, 且早春添加优于夏季添加。该研究对指导退化草地的恢复具有参考价值。

关键词: 草地生态系统, 草地施肥, 草地恢复, 碳循环, 氮磷互作

Abstract:

Aims Overgrazing induced reduction in supply of soil nutrients is a major mechanism leading to extensive grassland degradation in China. The capacity of carbon (C) sequestration was demoted in the degraded grassland ecosystems. However, it remains unclear whether the capacity of carbon sequestration in a degraded grassland can be restored by the supplement of nutrients to the soil. Net ecosystem CO₂ exchange (NEE), ecosystem respiration (ER) and gross ecosystem productivity (GEP) are important parameters describing the processes of ecosystem carbon cycle. Nitrogen (N) and phosphorus (P) are two limiting nutrients in typical steppe in China. To date, how these two nutrients alone or in combination affect the three parameters of carbon cycle (i.e., NEE, ER and GEP) in a degraded steppe community, especially their interactive effect, is poorly understood.

Methods To address these scientific questions, we conducted a field experiment in a degraded typical steppe community. Four treatments of nutrient addition were implemented: no nutrient addition (CK, control), adding N alone (10.5 g·m^-2, NH₄NO₃), adding P alone (7 g·m^-2, KH₂PO₄), and adding two nutrients in combination. Two stages were selected for fertilization: early-spring (April 21) and middle-summer (July 15).

Important findings Neither N nor P alone had significant effect on NEE, ER and GEP when nutrients applied at early-spring (April 21) or middle-summer (July 15), while their combination significantly increased the values ofNEE and GEP. 2) N and P exhibited strong synergistic effect on NEE, GEPand ER when applied in combination at early-spring (April 21), while a consistent additive effect between the two nutrients on the three carbon exchange parameters was observed when applied at middle-summer (July 15). Our findings have implications for the restoration of degraded grasslands. To restore the capacity of carbon sequestration of the degraded typical steppe ecosystem, supplying N and P in combination is better than a single nutrient alone, and appling these nutrients at spring is better than at summer.

Key words: grassland ecosystem, fertilization in grassland, grassland restoration, carbon cycle, interaction between nitrogen and phosphorus

吕亚香, 戚智彦, 刘伟, 孙佳美, 潘庆民. 早春和夏季氮磷添加对内蒙古典型草原退化群落碳交换的影响. 植物生态学报, 2021, 45(4): 334-344. DOI: 10.17521/cjpe.2020.0277

LÜ Ya-Xiang, QI Zhi-Yan, LIU Wei, SUN Jia-Mei, PAN Qing-Min. Effects of nitrogen and phosphorus addition at early-spring and middle-summer on ecosystem carbon exchanges of a degraded community in Nei Mongol typical steppe. Chinese Journal of Plant Ecology, 2021, 45(4): 334-344. DOI: 10.17521/cjpe.2020.0277

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2020.0277

https://www.plant-ecology.com/CN/Y2021/V45/I4/334

图/表 5

图1 氮、磷对碳交换参数互作效应示意图。N, 氮单独添加下氮对生态系统碳交换指标的效应; P, 磷单独添加下磷对生态系统碳交换指标的效应。NNP, 氮磷共同添加下氮对生态系统碳交换指标的效应; NP, 氮磷共同添加下氮和磷对生态系统碳交换指标的效应; PNP, 氮磷共同添加下磷对生态系统碳交换指标的效应。

Fig. 1 A conceptual framework illustrating interactive effects between nitrogen and phosphorus on parameters of carbon exchanges. N, effect of nitrogen on parameters of carbon exchanges under the scenario of only nitrogen addition; P, effect of phosphorus on parameters of carbon exchanges under the scenario of only phosphorus addition. NNP, effect of nitrogen on parameters of carbon exchanges under the scenario of nitrogen and phosphorus co-addition;NP, co-effect of nitrogen and phosphorus on parameters of carbon exchanges under the scenario of nitrogen and phosphorus co-addition; PNP, effect of phosphorus on parameters of carbon exchanges under the scenario of nitrogen and phosphorus co-addition.

图2 2019年实验区域日平均气温和日降水量动态。

Fig. 2 Dynamics in mean daily air temperature and mean daily precipitation in experimental area in 2019.

图3 不同时期氮磷添加对净生态系统碳交换(NEE, A)、生态系统呼吸(ER, B)和总生态系统生产力(GEP, C)的影响(平均值±标准误)。不同小写字母表示相同时期添加养分的各处理间差异达到显著水平(p< 0.05)。CK, 对照((0 g N + 0 g P)·m-2·a-1); N, 氮添加(10.5 g·m-2·a-1); P, 磷添加(7 g·m-2·a-1); NP, 氮磷共同添加((10.5 g N + 7 g P)·m-2·a-1)。

Fig. 3 Effects of timing of nitrogen and phosphorus addition on net ecosystem carbon exchange (NEE, A), ecosystem respiration (ER, B) and gross ecosystem productivity (GEP, C)(mean ± SE). Different lowercase letters indicate significant difference between treatments of nutrient addition at the same date (p < 0.05). CK, control ((0 g N +0 g P)·m -2·a-1); N, nitrogen addition at a rate of 10.5 g·m-2·a-1; P, phosphorus addition at the rate of 7 g·m-2·a-1; NP, nitrogen in combination with phosphorus addition at the rates of 10.5 and 7 g·m-2·a-1, respectively.

图4 氮(N)在无磷(P)添加和有磷添加情况下对净生态系统碳交换(NEE, A)、生态系统呼吸(ER, B)和总生态系统生产力(GEP, C)的作用以及磷在无氮添加和有氮添加情况下对NEE (D), ER (E)和GEP (F)的作用(平均值±标准误)。**,p < 0.01; ***, p < 0.001; ns, p> 0.05。

Fig. 4 Nitrogen (N)-induced changes in net ecosystem carbon exchange (NEE, A), ecosystem respiration (ER,B) and gross ecosystem productivity (GEP, C) with and without phosphorus (P) fertilization, and P-induced changes in NEE (D), ER(E) and GEP (F) with and without N fertilization (mean ± SE). **, p < 0.01; ***, p < 0.001; ns, p> 0.05.

图5 净生态系统碳交换(NEE, A、D)、生态系统呼吸(ER, B、E)和总生态系统生产力(GEP, C、F)与土壤温度和土壤水分的关系。

Fig. 5 Net ecosystem carbon exchange (NEE, A, D), ecosystem respiration (ER, B, E) and gross ecosystem productivity (GEP, C, F) in relation to soil temperature and soil moisture.

参考文献 49

[1]	Ågren GI, Wetterstedt JÅM, Billberger MFK (2012). Nutrient limitation on terrestrial plant growth—Modeling the interaction between nitrogen and phosphorus. New Phytologist, 194, 953-960. DOI URL
[2]	Allgeier JE, Rosemond AD, Layman CA (2011). The frequency and magnitude of non-additive responses to multiple nutrient enrichment. Journal of Applied Ecology, 48, 96-101. DOI URL
[3]	Bagchi S, Ritchie ME (2010). Introduced grazers can restrict potential soil carbon sequestration through impacts on plant community composition. Ecology Letters, 13, 959-968.
[4]	Bai X, Cheng JH, Zheng SX, Zhan SX, Bai YF ( 2014). Ecophysiological responses of Leymus chinensis to nitrogen and phosphorus additions in a typical steppe . Chinese Journal of Plant Ecology, 38, 103-115. DOI URL
	[ 白雪, 程军回, 郑淑霞, 詹书侠, 白永飞 ( 2014). 典型草原建群种羊草对氮磷添加的生理生态响应. 植物生态学报, 38, 103-115.]
[5]	Bai YF, Wu JG, Clark CM, Naeem S, Pan QM, Huang JH, Zhang LX, Han XG (2010). Tradeoffs and thresholds in the effects of nitrogen addition on biodiversity and ecosystem functioning: evidence from inner Mongolia Grasslands. Global Change Biology, 16, 358-372. DOI URL
[6]	Bai YF, Wu JG, Xing Q, Pan QM, Huang JH, Yang DL, Han XG (2008). Primary production and rain use efficiency across a precipitation gradient on the Mongolia plateau. Ecology, 89, 2140-2153. DOI URL
[7]	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
[8]	Chen Q, Hooper DU, Lin S (2011). Shifts in species composition constrain restoration of overgrazed grassland using nitrogen fertilization in Inner Mongolian steppe, China. PLOS ONE, 6, e16909. DOI: 10.1371/journal.pone.0016909. DOI URL
[9]	Chen SP, Lin GH, Huang JH, Jenerette GD (2009). Dependence of carbon sequestration on the differential responses of ecosystem photosynthesis and respiration to rain pulses in a semiarid steppe. Global Change Biology, 15, 2450-2461. DOI URL
[10]	Chen ZZ, Sheng XW, Yang ZG, Huang DH ( 1985). The ecological effects of fertiltzation during rainy season on various types of steppe on the Xilin River Valley, Inner Mongolia//Inner Mongolia Grassland Ecosystem Research Station, Academia Sinica. Research on Grassland Ecosystem:No.1. Science Press, Beijing.225-232.
	[ 陈佐忠, 盛修武, 杨宗贵, 黄德华 ( 1985). 不同类型草原群落雨季施肥的生态效应//中国科学院内蒙古草原生态系统定位站. 草原生态系统研究: 第一集. 科学出版社, 北京. 225-232.]
[11]	Dong CC, Wang W, Liu HY, Xu XT, Zeng H (2019). Temperate grassland shifted from nitrogen to phosphorus limitation induced by degradation and nitrogen deposition: evidence from soil extracellular enzyme stoichiometry. Ecological Indicators, 101, 453-464. DOI URL
[12]	Elser JJ, Bracken MES, Cleland EE, Gruner DS, Harpole WS, Hillebrand H, Ngai JT, Seabloom EW, Shurin JB, Smith JE (2007). Global analysis of nitrogen and phosphorus limitation of primary producers in freshwater, marine and terrestrial ecosystems. Ecology Letters, 10, 1135-1142. DOI URL
[13]	Guan SY, Qi PQ, Kang SA, Chang JB ( 1997). Effects on the steppe soil nutrient contents under different grazing intensities//Inner Mongolia Grassland Ecosystem Research Station, Academia Sinica. Research on Grassland Ecosystem: No.5. Science Press, Beijing. 17-22.
	[ 关世英, 齐沛钦, 康师安, 常进宝 ( 1997). 不同牧压强度对草原土壤养分含量的影响初析//中国科学院内蒙古草原生态系统定位站. 草原生态系统研究:第五集. 科学出版社, 北京. 17-22.]
[14]	Han WX, Fang JY, Guo DL, Zhang Y (2005). Leaf nitrogen and phosphorus stoichiometry across 753 terrestrial plant species in China. New Phytologist, 168, 377-385. DOI URL
[15]	Hao YB, Zhou CT, Liu WJ, Li LF, Kang XM, Jiang LL, Cui XY, Wang YF, Zhou XQ, Xu CY (2017). Aboveground net primary productivity and carbon balance remain stable under extreme precipitation events in a semiarid steppe ecosystem. Agricultural and Forest Meteorology, 240- 241, 1-9.
[16]	Harpole WS, Ngai JT, Cleland EE, Seabloom EW, Borer ET, Bracken MES, Elser JJ, Gruner DS, Hillebrand H, Shurin JB, Smith JE (2011). Nutrient co-limitation of primary producer communities. Ecology Letters, 14, 852-862. DOI URL
[17]	Harpole WS, Potts DL, Suding KN (2007). Ecosystem responses to water and nitrogen amendment in a California grassland. Global Change Biology, 13, 2341-2348. DOI URL
[18]	Hasi MQ, Zhang XY, Niu GX, Wang YL, Huang JH ( 2018). Effects of nitrogen addition on ecosystem CO₂ exchange in a meadow steppe, Inner Mongolia . Chinese Bulletin of Botany, 53, 27-41.
	[哈斯木其尔, 张学耀, 牛国祥, 王银柳, 黄建辉 ( 2018). 氮素添加对内蒙古草甸草原生态系统CO₂交换的影响. 植物学报, 53, 27-41.]
[19]	Jasoni RL, Smith SD, Arnone III JA (2005). Net ecosystem CO₂ exchange in Mojave Desert shrublands during the eighth year of exposure to elevated CO₂. Global Change Biology, 11, 749-756. DOI URL
[20]	Jiang J, Wang YP, Yang YH, Yu MX, Wang C, Yan JH (2019). Interactive effects of nitrogen and phosphorus additions on plant growth vary with ecosystem type. Plant and Soil, 440, 523-537. DOI
[21]	Li JD, Liu JX ( 1981). Preliminary report on application of nitrogen fertilizer in Leymus chinensisgrassland . Chinese Grassland, 3, 58-59.
	[ 李建东, 刘建新 ( 1981). 羊草草原施用氮肥的研究初报. 中国草原, 3, 58-59.]
[22]	Li P, Sayer EJ, Jia Z, Liu WX, Wu YT, Yang S, Wang CZ, Yang L, Chen DM, Bai YF, Liu LL (2020). Deepened winter snow cover enhances net ecosystem exchange and stabilizes plant community composition and productivity in a temperate grassland. Global Change Biology, 26, 3015-3027. DOI URL
[23]	Li RX, Liu QF, Li D, Cheel H, Zhao MY, Niu JM ( 2018). Ecological stoicheiometry of degraded Leymus chinensis steppe in Xilin River Basin . Chinese Journal of Grassland, 40, 75-80.
	[ 李瑞新, 刘庆福, 李丹, 澈格勒很, 赵梦颖, 牛建明 ( 2018). 锡林河流域退化羊草草原的生态化学计量学研究. 中国草地学报, 40, 75-80.]
[24]	Li SL, Chen YJ, Guan SY, Kang SA ( 2002). Relationships between soil degradation and rangeland degradation. Journal of Arid Land Resources and Environment, 16, 92-95.
	[ 李绍良, 陈有君, 关世英, 康师安 ( 2002). 土壤退化与草地退化关系的研究. 干旱区资源与环境, 16, 92-95.]
[25]	Li YH ( 1988). The divergence and convergence of Aneurolepidium chinense steppe and Stipa grandis steppe under the grazing influence in Xilin River valley, Inner Mongolia . Acta Phytoecologica et Geobotanica Sinica, 12, 189-196.
	[ 李永宏 ( 1988). 内蒙古锡林河流域羊草草原和大针茅草原在放牧影响下的分异和趋同. 植物生态学报, 12, 189-196.]
[26]	Niu SL, Wu MY, Han Y, Xia JY, Zhang Z, Yang HJ, Wan SQ (2010). Nitrogen effects on net ecosystem carbon exchange in a temperate steppe. Global Change Biology, 16, 144-155. DOI URL
[27]	Niu SL, Yang HJ, Zhang Z, Wu MY, Lu Q, Li LH, Han XG, Wan SQ (2009). Non-additive effects of water and nitrogen addition on ecosystem carbon exchange in a temperate steppe. Ecosystems, 12, 915-926. DOI URL
[28]	Oberbauer SF, Tweedie CE, Welker JM, Fahnestock JT, Henry GHR, Webber PJ, Hollister RD, Walker MD, Kuchy A, Elmore E, Starr G (2007). Tundra CO₂ fluxes in response to experimental warming across latitudinal and moisture gradients. Ecological Monographs, 77, 221-238. DOI URL
[29]	Pan QM, Bai YF, Han XG, Yang JC ( 2004). Studies on the fate of labelled nitrogen applied to a Leymus Chinensis community of typical steppe in Inner Mongolia grassland . Acta Phytoecologica Sinica, 28, 665-671.
	[ 潘庆民, 白永飞, 韩兴国, 杨景成 ( 2004). 内蒙古典型草原羊草群落氮素去向的示踪研究. 植物生态学报, 28, 665-671.]
[30]	Raich JW, Potter CS (1995). Global patterns of carbon dioxide emissions from soils. Global Biogeochemical Cycles, 9, 23-36. DOI URL
[31]	Rong YP, Han JG, Wang P, Mao PS ( 2001). The effects of grazing intensity on soil physics and chemical properties. Grassland of China, 23, 41-47.
	[ 戎郁萍, 韩建国, 王培, 毛培胜 ( 2001). 放牧强度对草地土壤理化性质的影响. 中国草地, 23, 41-47.]
[32]	Saarnio S, Järviö S, Saarinen T, Vasander H, Silvola J (2003). Minor changes in vegetation and carbon gas balance in a boreal mire under a raised CO₂ or NH₄NO₃ supply. Ecosystems, 6, 46-60. DOI URL
[33]	Sanyal SK, de Datta SK (1991). Chemistry of Phosphorus Transformations in Soil. Springer,New York.
[34]	Shen HH, Zhu YK, Zhao X, Geng XQ, Gao SQ, Fang JY ( 2016). Analysis of current grassland resources in China. Chinese Science Bulletin, 61, 139-154.
	[ 沈海花, 朱言坤, 赵霞, 耿晓庆, 高树琴, 方精云 ( 2016). 中国草地资源的现状分析. 科学通报, 61, 139-154.]
[35]	Tian DS, Niu SL (2015). A global analysis of soil acidification caused by nitrogen addition. Environmental Research Letters, 10, 024019. DOI: 10.1088/1748-9326/10/2/024019. DOI URL
[36]	Tian DS, Niu SL, Pan QM, Ren TT, Chen SP, Bai YF, Han XG (2016). Nonlinear responses of ecosystem carbon fluxes and water-use efficiency to nitrogen addition in Inner Mongolia grassland. Functional Ecology, 30, 490-499. DOI URL
[37]	Vose JM, Elliott KJ, Johnson DW, Tingey DT, Johnson MG (1997). Soil respiration response to three years of elevated CO₂ and N fertilization in ponderosa pine (Pinus ponderosa Doug. ex Laws.). Plant and Soil, 190, 19-28. DOI URL
[38]	Wang B, Li J, Jiang WW, Zhao L, Gu S ( 2012). Impacts of the rangeland degradation on CO₂ flux and the underlying mechanisms in the Three-River Source Region on the Qinghai-Tibetan Plateau . China Environmental Science, 32, 1764-1771.
	[ 王斌, 李洁, 姜微微, 赵亮, 古松 ( 2012). 草地退化对三江源区高寒草甸生态系统CO₂通量的影响及其原因. 中国环境科学, 32, 1764-1771.]
[39]	Wang JW, Cai YQ ( 1988). Study on genesis, types and characteristics of the soils of the Xilin River Basin//Inner Mongolia Grassland Ecosystem Research Station, Academia Sinica. Research on Grassland Ecosystem: No.3. Science Press, Beijing. 24-83.
	[ 汪久文, 蔡蔚祺 ( 1988). 锡林河流域土壤的发生类型及其性质的研究//中国科学院内蒙古草原生态系统定位站. 草原生态系统研究:第三集. 科学出版社, 北京. 24-83.]
[40]	Wang WY, Wang QJ, Wang G, Jing ZC ( 2007). Effects of land degradation and rehabilitation on vegetation carbon and nitrogen content of alpine meadow in China. Journal of Plant Ecology(Chinese Version) , 31, 1073-1078.
	[ 王文颖, 王启基, 王刚, 景增春 ( 2007). 高寒草甸土地退化及其恢复重建对植被碳、氮含量的影响. 植物生态学报, 31, 1073-1078.]
[41]	Xia JY, Niu SL, Wan SQ (2009). Response of ecosystem carbon exchange to warming and nitrogen addition during two hydrologically contrasting growing seasons in a temperate steppe. Global Change Biology, 15, 1544-1556. DOI URL
[42]	Yan LM, Chen SP, Huang JH, Lin GH (2011). Increasing water and nitrogen availability enhanced net ecosystem CO₂ assimilation of a temperate semiarid steppe. Plant and Soil, 349, 227-240. DOI URL
[43]	Yang Q, Wang W, Zeng H ( 2018). Effects of nitrogen addition on the plant diversity and biomass of degraded grasslands of Nei Mongol, China. Chinese Journal of Plant Ecology, 42, 430-441. DOI URL
	[ 杨倩, 王娓, 曾辉 ( 2018). 氮添加对内蒙古退化草地植物群落多样性和生物量的影响. 植物生态学报, 42, 430-441.]
[44]	Yang Y ( 2005). Relationship Between Soil Available Phosphorus and Above-ground Net Primary Productivity and Response of Soil Available Phosphorus to Nutrient Addition in Leymus chinensis Steppe in Inner Mongolia. Master degree dissertation, Institute of Botany, Chinese Academy of Sciences,Beijing. 27-31.
	[ 杨阳 ( 2005). 内蒙古羊草草原土壤有效磷与地上净初级生产力间的关系以及对养分添加的响应. 硕士学位论文, 中国科学院植物研究所, 北京. 27-31.]
[45]	Zhou GY, Luo Q, Chen YJ, He M, Zhou LY, Frank D, He YH, Fu YL, Zhang BC, Zhou XH (2019). Effects of livestock grazing on grassland carbon storage and release override impacts associated with global climate change. Global Change Biology, 25, 1119-1132. DOI URL
[46]	Zhou HK, Zhao XQ, Zhou L, Liu W, Li YN, Tang YH ( 2005). A study on correlations between vegetation degradation and soil degradation in the ‘Alpine Meadow’ of the Qinghai- Tibetan Plateau. Acta Prataculturae Sinica, 14, 31-40.
	[ 周华坤, 赵新全, 周立, 刘伟, 李英年, 唐艳鸿 ( 2005). 青藏高原高寒草甸的植被退化与土壤退化特征研究. 草业学报, 14, 31-40.]
[47]	Zhou W, Gang CC, Zhou L, Chen YZ, Li JL, Ju WM, Odeh I (2014). Dynamic of grassland vegetation degradation and its quantitative assessment in the northwest China. Acta Oecologica, 55, 86-96. DOI URL
[48]	Zong N, Shi PL, Jiang J, Meng FS, Ma WL, Xiong DP, Song MH, Zhang XZ ( 2013). Effects of fertilization and grazing exclosure on vegetation recovery in a degraded alpine meadow on the Tibetan Plateau. Chinese Journal of Applied and Environmental Biology, 19, 905-913. DOI URL
	[ 宗宁, 石培礼, 蔣婧, 孟丰收, 马维玲, 熊定鹏, 宋明华, 张宪洲 ( 2013). 施肥和围栏封育对退化高寒草甸植被恢复的影响. 应用与环境生物学报, 19, 905-913.]
[49]	Zong N, Shi PL, Niu B, Jiang J, Song MH, Zhang XZ, He YT ( 2014). Effects of nitrogen and phosphorous fertilization on community structure and productivity of degraded alpine meadows in northern Tibet, China. Chinese Journal of Applied Ecology, 25, 3458-3468.
	[ 宗宁, 石培礼, 牛犇, 蒋婧, 宋明华, 张宪洲, 何永涛 ( 2014). 氮磷配施对藏北退化高寒草甸群落结构和生产力的影响. 应用生态学报, 25, 3458-3468.]