施肥和放牧对青藏高原高寒草甸物种丰富度的影响

doi:10.3724/SP.J.1258.2014.00101

摘要/Abstract

摘要：

在草地生态系统中, 施肥通常会导致生物多样性下降, 但是关于引起生物多样性下降的机制还存在着很大的争议。该研究基于一个4年的施肥实验, 试图通过个体大小的不整齐性和单位植物氮含量, 定性地揭示青藏高原东部高寒草甸施肥后多样性下降的原因。研究显示: 在封育地, 施肥致使个体大小不整齐性增加了15%, 并不同程度地增加了物种的高度。同时, 施肥使物种间单位植物氮含量存在显著差异的数目降低了65%。施肥后光竞争加剧, 导致大个体植物排斥小个体植物, 进而引起了物种丰富度下降29.6%。与封育地不同, 放牧地施肥并没有改变个体大小不整齐性和物种的高度, 而是使物种间单位植物氮含量存在显著差异的数目增加了11.4%。施肥并没有改变放牧地的光竞争强度, 而是增加了物种间对土壤营养元素氮的竞争强度, 进而引起了物种丰富度下降17.3%。该研究还发现, 放牧施肥地的物种丰富度下降速度和等级显著低于封育施肥地的物种丰富度下降速度和等级, 这表明放牧减缓了施肥对物种丰富度的影响力。

关键词: 高寒草甸, 地下竞争, 群落生态学, 光竞争, 大小不整齐性, 物种丰富度

Abstract:

Aims Plant species diversity often declines when nutrients are added in grassland. However, the mechanisms for explaining biodiversity loss due to nutrient enrichment have remained controversial. Our objective was to explore the potential mechanisms of diversity decline.
Methods In this paper, based on a four-year experiment of nutrient addition and grazing in an alpine plant community, we investigate the potential mechanisms of diversity loss by comparing the above- and below-ground competitions using coefficient of variation and nitrogen use efficiency under fertilization scenario both in grazed and non-grazed plots.
Important findings Fertilization increased the size inequality of individuals by 15%, increased species height by different degrees, and reduced the number of species pairs that differed significantly in nitrogen content by 65% in the non-grazed plots. The results indicate that the large-sized individuals out-competed the small-sized individuals due to competition for light, which led to a decline in species richness by 29.6% in the non-grazed plots following fertilization. In contrast, fertilization did not change the size inequality of individuals and species height in the grazed plots, and increased the number of species pairs that differed significantly in nitrogen content by 11.4%, implying that an increased competition for soil nitrogen among species reduced the species richness by 17.3%. Our study also suggests that grazing delayed the effect of fertilization on species richness as inferred by the lower rate of species loss in the grazed plots.

Key words: alpine meadow, belowground competition, community ecology, light competition, size inequality, species richness

杨中领, 苏芳龙, 苗原, 钟明星, 肖蕊. 施肥和放牧对青藏高原高寒草甸物种丰富度的影响. 植物生态学报, 2014, 38(10): 1074-1081. DOI: 10.3724/SP.J.1258.2014.00101

YANG Zhong-Ling, SU Fang-Long, MIAO Yuan, ZHONG Ming-Xing, XIAO Rui. Effects of fertilization and grazing on species richness in an alpine meadow of Qinghai-Xizang Plateau. Chinese Journal of Plant Ecology, 2014, 38(10): 1074-1081. DOI: 10.3724/SP.J.1258.2014.00101

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https://www.plant-ecology.com/CN/Y2014/V38/I10/1074

图/表 5

参考文献 30

[1]	Aarssen LW, Schamp BS, Pither J (2006). Why are there so many small plants? Implications for species coexistence. Journal of Ecology, 94,569-580. DOI URL
[2]	Abrams PA (1995). Monotonic or unimodal diversity- productivity gradients: What does competition theory predict? Ecology, 76,2019-2027. DOI URL
[3]	Cardinale BJ, Duffy JE, Gonzalez A, Hooper DU, Perrings C, Venail P, Narwani A, Mace GM, Tilman D, Wardle DA, Kinzig AP, Daily GC, Loreau M, Grace JB, Larigauderie A, Srivastava DS, Naeem S (2012). Biodiversity loss and its impact on humanity. Nature, 486,59-67. DOI URL
[4]	Dickson TL, Foster BL (2011). Fertilization decreases plant biodiversity even when light is not limiting. Ecology Letters, 14,380-388. DOI URL
[5]	Gough L, Gross KL, Cleland EE, Clark CM, Collins SL, Fargione JE, Pennings SC, Suding KN (2012). Incorporating clonal growth form clarifies the role of plant height in response to nitrogen addition. Oecologia, 169,1053-1062. DOI URL
[6]	Grime JP (2002). Plant Strategies, Vegetation Processes, and Ecosystem Properties, 2nd edn. Wiley, Chichester, UK.
[7]	Hautier Y, Niklaus PA, Hector A (2009). Competition for light causes plant biodiversity loss after eutrophication. Science, 324,636-638. DOI URL PMID
[8]	Hillebrand H, Gruner DS, Borer ET, Bracken ES, Cleland EE, Elser JJ, Harpole WS, Ngai JT, Seabloom EW, Shurin JB, Smith JE (2007). Consumer versus resource control of producer diversity depends on ecosystem type and producer community structure. Proceedings of the National Academy of Sciences of the United States of America, 104,10904-10909.
[9]	Lan Z, Bai Y (2012). Testing mechanisms of N-enrichment induced species loss in a semiarid Inner Mongolia grassland: critical thresholds and implications for long-term ecosystem responses. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences, 367,3125-3134.
[10]	Luo YJ, Qin GL, Du GZ (2006). Importance of assemblage- level thinning: a field experiment in an alpine meadow on the Tibet Plateau. Journal of Vegetation Science, 17,417-424.
[11]	Mittelbach GG, Steiner CF, Scheiner SM, Gross KL, Reynolds HL, Waide RB, Willig MR, Dodson S, Gough L (2001). What is the observed relationship between species richness and productivity? Ecology, 82,2381-2396. DOI URL
[12]	Moles AT, Warton DI, Warman L, Swenson NG, Laffan SW, Zanne AE, Pitman A, Hemmings FA, Leishman MR (2009). Global patterns in plant height. Journal of Ecology, 97,923-932. DOI URL
[13]	Newbery DMC, Newman EI (1978). Competition between grassland plants of different initial sizes. Oecologia, 33,361-380. DOI URL PMID
[14]	Newman EI (1973). Competition and diversity in herbaceous vegetation. Nature, 244,310. DOI URL
[15]	Niu KC, Luo YJ, Choler P, Du GZ (2008). The role of biomass allocation strategy in diversity loss due to fertilization. Basic and Applied Ecology, 9,485-493. DOI URL
[16]	Rajaniemi TK (2002). Why does fertilization reduce plant species diversity? Testing three competition-based hypotheses. Journal of Ecology, 90,316-324. DOI URL
[17]	Stevens CJ, Dise NB, Mountford OJ, Gowing DJ (2004). Impact of nitrogen deposition on the species richness of grasslands. Science, 303,1876-1879. DOI URL PMID
[18]	Stevens MHH, Carson WP (1999a). The significance of assemblage-level thinning for species richness. Journal of Ecology, 87,490-502. DOI URL
[19]	Stevens MHH, Carson WP (1999b). Plant density determines species richness along an experimental fertility gradient. Ecology, 80,455-465. DOI URL
[20]	Suding KN, Collings SL, Gough L, Clark C, Cleland EE, Gross KL, Milchunas DG, Pennings S (2005). Functional and abundance-based mechanisms explain diversity loss due to N fertilization. Proceedings of the National Academy of Sciences of the United States of America, 102,4387-4392.
[21]	Tilman D (1982). Resource Competition and Community Structure. Princeton University Press, Princeton, USA.
[22]	Tilman D (1988). Dynamics and Structure of Plant Communities. Princeton University Press, Princeton, USA.
[23]	Tilman D, Pacala S (1993). The maintenance of species richness in plant communities. In: Ricklefs RE, Schluter D eds. Species Diversity in Ecological Communities. University of Chicago Press, Chicago. 13-25.
[24]	van Ruijven J, Berendse F (2005). Diversity-productivity relationships: initial effects, long-term patterns, and underlying mechanisms. Proceedings of the National Academy of Sciences of the United States of America, 102,695-700.
[25]	Waide RB, Willig MR, Steiner CF, Mittelbach G, Gough L, Dodson SI, Juday GP, Parmenter R (1999). The relationship between productivity and species richness. Annual Review of Ecology and Systematics, 30,257-300. DOI URL
[26]	Weiher E, Clarke GDP, Keddy PA (1998). Community assembly rules, morphological dispersion, and the coexistence of plant species. Oikos, 81,309-322. DOI URL
[27]	Weiner J (1985). Size hierarchies in experimental populations of annual plants. Ecology, 66,743-752. DOI URL
[28]	Yang Z, Guo H, Zhang J, Du GZ (2013). Stochastic and deterministic processes together determine alpine meadow plant community composition on the Tibetan Plateau. Oecologia, 171,495-504. DOI URL
[29]	Yang Z, van Ruijven J, Du GZ (2011). The effects of long-term fertilization on the temporal stability of alpine meadow communities. Plant and Soil, 345,315-324. DOI URL
[30]	Yang Z, Powell JR, Zhang C, Du GZ (2012). The effect of environmental and phylogenetic drivers on community assembly in an alpine meadow community. Ecology, 93,2321-2328.

物种 Species	植物高度 Plant height (cm)
物种 Species	封育 Enclosure	封育施肥 Enclosure + fertilization	放牧 Grazing	放牧施肥 Grazing + fertilization
青藏大戟 Euphorbia altotibetica	10.5	19.9	6.9	7.8
钝裂银莲花 Anemone obtusiloba	11.4	18.4	5.4	9.2
垂穗披碱草 Elymus nutans	40.5	66.7	26.5	24.2
莓叶委陵菜Potentilla fragarioids	11.0	12.0	6.6	6.1
阿尔泰蒲公英Taraxacum altaicum	6.5	15.9	7.1	7.5
米口袋Gueldenstaedtia verna	8.7	15.1	5.5	5.8
蓬子菜Galium verum	14.1	25.3	6.6	9.0
四川嵩草Kobresia setchwanensis	34.1	42.2	21.3	25.2
马尔康柴胡 Bupleurum malconense	20.5	20.0	7.9	6.9
冷地早熟禾Poa crymophila	33.1	56.3	16.4	18.1
钝苞雪莲Saussurea nigrescens	13.6	14.2	6.4	7.0
高山韭Allium sikkimense	17.5	27.6	8.9	14.3
菭草Koeleria cristata	22.7	46.3	22.5	17.0
细叶亚菊Ajania tenuifolia	12.7	20.6	8.2	5.5
草玉梅Anemone rivularis	20.0	29.2	11.9	9.9
花苜蓿Medicago ruthenica	10.1	19.0	5.5	6.7
椭圆叶花锚Halenia elliptica	20.1	19.4	9.9	8.9
展毛翠雀花 Delphinium kamaonense	16.0	25.1	8.0	8.2
丝叶毛茛 Ranunculus tanguticusvar.capillaceus	13.2	23.3	7.4	8.2
乳白香青Anaphalis lactea	8.1	8.6	3.6	4.8
甘肃棘豆Oxytropis kansuensis	12.1	16.0	7.1	6.5
大籽蒿Artemisia sieversiana	17.1	34.4	6.2	10.1
甘肃马先蒿 Pedicularis kansuensis	15.4	21.8	7.6	5.9
高原毛茛Ranunculus tanguticus	10.2	14.7	6.9	7.3
芒剪股颖 Agrostis trinii	21.9	39.2	15.0	18.6
扁蕾Gentianopsis barbata	19.6	25.4	15.5	16.9

物种 Species	植物高度 Plant height (cm)
物种 Species	封育 Enclosure	封育施肥 Enclosure + fertilization	放牧 Grazing	放牧施肥 Grazing + fertilization
青藏大戟 Euphorbia altotibetica	10.5	19.9	6.9	7.8
钝裂银莲花 Anemone obtusiloba	11.4	18.4	5.4	9.2
垂穗披碱草 Elymus nutans	40.5	66.7	26.5	24.2
莓叶委陵菜Potentilla fragarioids	11.0	12.0	6.6	6.1
阿尔泰蒲公英Taraxacum altaicum	6.5	15.9	7.1	7.5
米口袋Gueldenstaedtia verna	8.7	15.1	5.5	5.8
蓬子菜Galium verum	14.1	25.3	6.6	9.0
四川嵩草Kobresia setchwanensis	34.1	42.2	21.3	25.2
马尔康柴胡 Bupleurum malconense	20.5	20.0	7.9	6.9
冷地早熟禾Poa crymophila	33.1	56.3	16.4	18.1
钝苞雪莲Saussurea nigrescens	13.6	14.2	6.4	7.0
高山韭Allium sikkimense	17.5	27.6	8.9	14.3
菭草Koeleria cristata	22.7	46.3	22.5	17.0
细叶亚菊Ajania tenuifolia	12.7	20.6	8.2	5.5
草玉梅Anemone rivularis	20.0	29.2	11.9	9.9
花苜蓿Medicago ruthenica	10.1	19.0	5.5	6.7
椭圆叶花锚Halenia elliptica	20.1	19.4	9.9	8.9
展毛翠雀花 Delphinium kamaonense	16.0	25.1	8.0	8.2
丝叶毛茛 Ranunculus tanguticusvar.capillaceus	13.2	23.3	7.4	8.2
乳白香青Anaphalis lactea	8.1	8.6	3.6	4.8
甘肃棘豆Oxytropis kansuensis	12.1	16.0	7.1	6.5
大籽蒿Artemisia sieversiana	17.1	34.4	6.2	10.1
甘肃马先蒿 Pedicularis kansuensis	15.4	21.8	7.6	5.9
高原毛茛Ranunculus tanguticus	10.2	14.7	6.9	7.3
芒剪股颖 Agrostis trinii	21.9	39.2	15.0	18.6
扁蕾Gentianopsis barbata	19.6	25.4	15.5	16.9

物种 Species	平均植物氮含量 Mean plant nitrogen content (mg·g^-1)
物种 Species	封育 Enclosure	封育施肥 Enclosure + fertilization	放牧 Grazing	放牧施肥 Grazing + fertilization
青藏大戟 Euphorbia altotibetica	14.7	15.9	11.7	14.5
钝裂银莲花 Anemone obtusiloba	14.5	15.8	16.5	16.2
垂穗披碱草 Elymus nutans	7.6	7.5	11.5	10.0
莓叶委陵菜Potentilla fragarioids	13.3	13.8	13.0	15.3
阿尔泰蒲公英Taraxacum altaicum	15.5	17.3	18.1	17.0
米口袋Gueldenstaedtia verna	21.6	24.9	24.8	25.7
蓬子菜Galium verum	14.2	14.8	15.2	20.0
四川嵩草Kobresia setchwanensis	10.3	11.9	9.6	10.7
马尔康柴胡 Bupleurum smithii	13.0	14.8	18.5	16.2
冷地早熟禾Poa crymophila	7.7	7.1	6.5	8.2
钝苞雪莲 Saussurea nigrescens	10.4	9.8	11.2	12.2
高山韭Allium sikkimense	14.5	16.4	14.1	13.7
菭草Koeleria cristata	9.2	10.6	10.3	11.6
细叶亚菊Ajania tenuifolia	13.3	10.2	14.5	16.7
草玉梅Anemone rivularis	14.3	17.3	16.9	15.4
花苜蓿Medicago ruthenica	22.9	25.0	25.9	27.0
椭圆叶花锚Halenia elliptica	13.1	13.3	14.7	14.7
展毛翠雀花 Delphinium kamaonense	10.7	11.6	13.4	13.7
丝叶毛茛 Ranunculus tanguticusvar.capillaceus	13.5	15.5	11.3	13.7
乳白香青Anaphalis lactea	9.9	10.1	10.5	10.9
甘肃棘豆Oxytropis kansuensis	27.1	28.3	28.8	29.7
大籽蒿Artemisia sieversiana	12.1	12.4	12.8	18.7
甘肃马先蒿 Pedicularis kansuensis	19.5	21.8	23.3	27.3
高原毛茛Ranunculus tanguticus	12.8	13.5	11.9	12.9
芒剪股颖 Agrostis trinii	9.5	10.4	12.4	13.7
扁蕾Gentianopsis barbata	10.5	14.4	15.2	16.3

物种 Species	平均植物氮含量 Mean plant nitrogen content (mg·g^-1)
物种 Species	封育 Enclosure	封育施肥 Enclosure + fertilization	放牧 Grazing	放牧施肥 Grazing + fertilization
青藏大戟 Euphorbia altotibetica	14.7	15.9	11.7	14.5
钝裂银莲花 Anemone obtusiloba	14.5	15.8	16.5	16.2
垂穗披碱草 Elymus nutans	7.6	7.5	11.5	10.0
莓叶委陵菜Potentilla fragarioids	13.3	13.8	13.0	15.3
阿尔泰蒲公英Taraxacum altaicum	15.5	17.3	18.1	17.0
米口袋Gueldenstaedtia verna	21.6	24.9	24.8	25.7
蓬子菜Galium verum	14.2	14.8	15.2	20.0
四川嵩草Kobresia setchwanensis	10.3	11.9	9.6	10.7
马尔康柴胡 Bupleurum smithii	13.0	14.8	18.5	16.2
冷地早熟禾Poa crymophila	7.7	7.1	6.5	8.2
钝苞雪莲 Saussurea nigrescens	10.4	9.8	11.2	12.2
高山韭Allium sikkimense	14.5	16.4	14.1	13.7
菭草Koeleria cristata	9.2	10.6	10.3	11.6
细叶亚菊Ajania tenuifolia	13.3	10.2	14.5	16.7
草玉梅Anemone rivularis	14.3	17.3	16.9	15.4
花苜蓿Medicago ruthenica	22.9	25.0	25.9	27.0
椭圆叶花锚Halenia elliptica	13.1	13.3	14.7	14.7
展毛翠雀花 Delphinium kamaonense	10.7	11.6	13.4	13.7
丝叶毛茛 Ranunculus tanguticusvar.capillaceus	13.5	15.5	11.3	13.7
乳白香青Anaphalis lactea	9.9	10.1	10.5	10.9
甘肃棘豆Oxytropis kansuensis	27.1	28.3	28.8	29.7
大籽蒿Artemisia sieversiana	12.1	12.4	12.8	18.7
甘肃马先蒿 Pedicularis kansuensis	19.5	21.8	23.3	27.3
高原毛茛Ranunculus tanguticus	12.8	13.5	11.9	12.9
芒剪股颖 Agrostis trinii	9.5	10.4	12.4	13.7
扁蕾Gentianopsis barbata	10.5	14.4	15.2	16.3