藏北高山嵩草草甸群落特征及生产力对模拟增温幅度的响应
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摘要
青藏高原气候严酷,陆地表层生态系统脆弱,其高寒植物群落特征及生态系统生产力对气候变化的响应极其敏感。利用开顶箱(OTCs,Open Top Chambers)式装置在藏北高山嵩草(Kobresia pygmaea)草甸设置不同增温梯度实验(W1、W2、W3、W4),探究增温对高寒草甸植物群落特征及地上生产力的影响。研究结果表明:1)与对照样地相比,增温减少了植物群落总盖度(2015年,W1、W2、W3、W4分别显著减少了28%、23%、59%、60%; 2016年,W4显著减少了83%)和高山嵩草盖度(2015年,W1、W2、W3、W4分别显著减少了26%、33%、681%、64%; 2016年,W4显著减少了85%),而低幅度增温(W1、W2)对委陵菜属植物盖度无显著影响,高幅度增温(W3、W4)显著减少了委陵菜属植物盖度(2015年,W3、W4分别显著减少了58%和60%;2016年,W4显著减少了71%); 2)对整个植物群落而言,增温幅度较低时,增温对群落的生长和生物量的积累有促进作用,当温度升高超过一定程度,这种促进作用会逐渐减弱甚至变成抑制作用(2015年,W4显著减少了地上生物量69%; 2016年,W4显著减少了地上生物量82%); 3)高山嵩草盖度和其他物种总盖度存在显著的年际差异,而委陵菜属植物盖度无明显的年际变化。研究结果预示着,一定程度的升温会促进高寒草甸植物群落的生长,但温度升高超过一定幅度时,会导致草地生产力下降,草地退化加剧,同时当地群落中委陵菜属植物在全球变化背景下相对稳定,这类物种在未来气候变暖的背景下可能具有更强的竞争力。
The community characteristics and productivity of alpine ecosystems are extremely sensitive to climate change in Qinghai-Tibet Plateau owing to harsh climatic environments. To explore the effects of warming on ecosystem productivity and their inter-annual differences in an alpine meadow,field experiments with temperature-gradient treatments(W1,W2,W3,and W4) using open top chambers(OTCs) were conducted in Tibetan Plateau. The results showed that the warming effect decreased the total coverage of the plant community(W1,W2,W3,and W4 significantly reduced plant community coverage by 28%,23%,59%,and 60% in 2015(P < 0. 05),respectively; W4 significantly reduced plant community coverage by 83% in 2016(P<0.05)) and the coverage of Kobresia pygmaea(W1,W2,W3,and W4 significantly reduced the coverage of K. pygmaea by 26%,33%,61%,and 64% in 2015(P<0.05),respectively; W4 significantly reduced the coverage of K. pygmaea by 85% in 2016(P<0.05)) compared with control treatment. The lower warming treatments(W1 and W2) had no significant effects on the coverage of Potentilla,whereas the higher warming treatments(W3 and W4)significantly reduced the coverage of Potentilla(W3,W4 significantly reduced the coverage of Potentilla by 58% and 60%in 2015(P< 0. 05),respectively; W4 significantly reduced the coverage of Potentilla by 71% in 2016(P < 0. 05). The warming treatments with a lower temperature range promoted growth and biomass accumulation of the community,whereas weakened the promotion effects or even inhibited growth and biomass accumulation when the temperature increased above a certain degree(W4 significantly reduced the aboveground biomass by 69% in 2015(P < 0.05); W4 significantly reduced the aboveground biomass by 82% in 2016(P<0.05)). There were significant differences in the coverage of K. pygmaea and other species in the growth season between 2015 and 2016,but no significant changes were observed for Potentilla coverage.This study indicated that moderate warming is conducive for plant growth,but excessive warming can lead to declined grassland productivity and the deterioration of alpine meadows. Furthermore,Potentilla species from local communities are more resistant to global change,indicating their strong competitiveness in facing future climate warming.
The community characteristics and productivity of alpine ecosystems are extremely sensitive to climate change in Qinghai-Tibet Plateau owing to harsh climatic environments. To explore the effects of warming on ecosystem productivity and their inter-annual differences in an alpine meadow,field experiments with temperature-gradient treatments(W1,W2,W3,and W4) using open top chambers(OTCs) were conducted in Tibetan Plateau. The results showed that the warming effect decreased the total coverage of the plant community(W1,W2,W3,and W4 significantly reduced plant community coverage by 28%,23%,59%,and 60% in 2015(P < 0. 05),respectively; W4 significantly reduced plant community coverage by 83% in 2016(P<0.05)) and the coverage of Kobresia pygmaea(W1,W2,W3,and W4 significantly reduced the coverage of K. pygmaea by 26%,33%,61%,and 64% in 2015(P<0.05),respectively; W4 significantly reduced the coverage of K. pygmaea by 85% in 2016(P<0.05)) compared with control treatment. The lower warming treatments(W1 and W2) had no significant effects on the coverage of Potentilla,whereas the higher warming treatments(W3 and W4)significantly reduced the coverage of Potentilla(W3,W4 significantly reduced the coverage of Potentilla by 58% and 60%in 2015(P< 0. 05),respectively; W4 significantly reduced the coverage of Potentilla by 71% in 2016(P < 0. 05). The warming treatments with a lower temperature range promoted growth and biomass accumulation of the community,whereas weakened the promotion effects or even inhibited growth and biomass accumulation when the temperature increased above a certain degree(W4 significantly reduced the aboveground biomass by 69% in 2015(P < 0.05); W4 significantly reduced the aboveground biomass by 82% in 2016(P<0.05)). There were significant differences in the coverage of K. pygmaea and other species in the growth season between 2015 and 2016,but no significant changes were observed for Potentilla coverage.This study indicated that moderate warming is conducive for plant growth,but excessive warming can lead to declined grassland productivity and the deterioration of alpine meadows. Furthermore,Potentilla species from local communities are more resistant to global change,indicating their strong competitiveness in facing future climate warming.
引文
[1] Ma Z Y,Liu H Y,Mi Z R,Zhang Z H,Wang Y H,Xu W,Jiang L,He J S. Climate warming reduces the temporal stability of plant community biomass production. Nature Communications,2017,8:15378.
[2] Cubasch U,Wuebbles D,Chen D,Facchini M C,Frame D,Mahowald N,Winther J G. Introduction//Climate Change 2013:The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge:Cambridge University Press,2013:741-866.
[3] Chen J,Luo Y Q,Xia J Y,Shi Z,Jiang L F,Niu S L,Zhou X H,Gao J J. Differential responses of ecosystem respiration components to experimental warming in a meadow grassland on the Tibetan Plateau. Agricultural and Forest Meteorology,2016,220:21-29.
[4] Wang S P,Duan J C,Xu P,Wang Y F,Zhang Z H,Rui Y C,Luo C Y,Xu B,Zhu X X,Chang X F,Cui X Y,Niu H S,Zhao X Q,Wang W Y. Effects of warming and grazing on soil N availability,species composition,and ANPP in an alpine meadow. Ecology,2012,93(11):2365-2376.
[5] Yang H J,Wu M Y,Liu W X,Zhang Z,Zhang N L,Wan S Q. Community structure and composition in response to climate change in a temperate steppe. Global Change Biology,2011,17(1):452-465.
[6] Yang Z L,Zhang Q,Su F L,Zhang C H,Pu Z C,Xia J Y,Wan S Q,Jiang L. Daytime warming lowers community temporal stability by reducing the abundance of dominant,stable species. Global Change Biology,2017,23(1):154-163.
[7] Corlett R T. Impacts of warming on tropical lowland rainforests. Trends in Ecology&Evolution,2011,26(11):606-613.
[8] Garcia R A,Cabeza M,Rahbek C,Araújo M B. Multiple dimensions of climate change and their implications for biodiversity. Science,2014,344(6183):1247579.
[9] Seddon A W R,Macias-Fauria M,Long P R,Benz D,Willis K J. Sensitivity of global terrestrial ecosystems to climate variability. Nature,2016,531(7593):229-232.
[10] Oliver T H,Isaac N J B,August T A,Woodcock B A,Roy D B,Bullock J M. Declining resilience of ecosystem functions under biodiversity loss.Nature Communications,2015,6:10122.
[11] Hautier Y,Seabloom E W,Borer E T,Adler P B,Harpole W S,Hillebrand H,Lind E M,Mac Dougall A S,Stevens C J,Bakker J D,Buckley Y M,Chu C J,Collins S L,Daleo P,Damschen E I,Davies K F,Fay P A,Firn J,Gruner D S,Jin V L,Klein J A,Knops J M H,La Pierre K J,Li W,Mc Culley R L,Melbourne B A,Moore J L,O'Halloran L R,Prober S M,Risch A C,Sankaran M,Schuetz M,Hector A.Eutrophication weakens stabilizing effects of diversity in natural grasslands. Nature,2014,508(7497):521-525.
[12] Hautier Y,Tilman D,Isbell F,Seabloom E W,Borer E T,Reich P B. Anthropogenic environmental changes affect ecosystem stability via biodiversity. Science,2015,348(6232):336-340.
[13] Lin D L,Xia J Y,Wan S Q. Climate warming and biomass accumulation of terrestrial plants:A meta-analysis. New Phytologist,2010,188(1):187-198.
[14] Wu Z T,Dijkstra P,Koch G W,Pe1uelas J,Hungate B A. Responses of terrestrial ecosystems to temperature and precipitation change:A metaanalysis of experimental manipulation. Global Change Biology,2011,17(2):927-942.
[15] De Boeck H J,Lemmens C M H M,Gielen B,Bossuyt H,Malchair S,Carnol M,Merckx R,Ceulemans R,Nijs I. Combined effects of climate warming and plant diversity loss on above-and below-ground grassland productivity. Environmental and Experimental Botany,2007,60(1):95-104.
[16] Saleska S R,Shaw M R,Fischer M L,Dunne J A,Still C J,Holman M L,Harte J. Plant community composition mediates both large transient decline and predicted long-term recovery of soil carbon under climate warming. Global Biogeochemical Cycles,2002,16(4):1055.
[17]宗宁,柴曦,石培礼,蒋婧,牛犇,张宪洲,何永涛.藏北高寒草甸群落结构与物种组成对增温与施氮的响应.应用生态学报,2016,27(12):3739-3748.
[18]李娜,王根绪,杨燕,高永恒,柳林安,刘光生.短期增温对青藏高原高寒草甸植物群落结构和生物量的影响.生态学报,2011,31(4):895-905.
[19] Post E,Pedersen C. Opposing plant community responses to warming with and without herbivores. Proceedings of the National Academy of Sciences of the United States of America,2008,105(34):12353-12358.
[20] Hooper D U,Adair E C,Cardinale B J,Byrnes J E K,Hungate B A,Matulich K L,Gonzalez A,Duffy J E,Gamfeldt L,O'Connor M I. A global synthesis reveals biodiversity loss as a major driver of ecosystem change. Nature,2012,486(7401):105-108.
[21] Luo C Y,Xu G P,Chao Z G,Wang S P,Lin X W,Hu Y G,Zhang Z H,Duan J C,Chang X F,Su A L,Li Y N,Zhao X Q,Du M Y,Tang Y H,Kimball B. Effect of warming and grazing on litter mass loss and temperature sensitivity of litter and dung mass loss on the Tibetan plateau.Global Change Biology,2010,16(5):1606-1617.
[22] Niu S L,Wu M Y,Han Y,Xia J Y,Li L H,Wan S Q. Water-mediated responses of ecosystem carbonuxes to climatic change in a temperate steppe. New Phytologist,2008,177(1):209-219.
[23] Rustad L,Campbell J,Marion G,Norby R,Mitchell M,Hartley A,Cornelissen J,Gurevitch J. A meta-analysis of the response of soil respiration,net nitrogen mineralization,and aboveground plant growth to experimental ecosystem warming. Oecologia,2001,126(4):543-562.
[24] Dieleman W I J,Vicca S,Dijkstra F A,Hagedorn F,Hovenden M J,Larsen K S,Morgan J A,Volder A,Beier C,Dukes J S,King J,Leuzinger S,Linder S,Luo Y Q,Oren R,De Angelis P,Tingey D,Hoosbeek M R,Janssens I A. Simple additive effects are rare:a quantitative review of plant biomass and soil process responses to combined manipulations of CO2and temperature. Global Change Biology,2012,18(9):2681-2693.
[25] Ward J Y,Tissue D T,Thomas R B,Strain B R. Comparative responses of model C3and C4plants to drought in low and elevated CO2. Global Change Biology,1999,5(8):857-867.
[26] Gundale M J,Nilsson M,Bansal S,Jderlund A. The interactive effects of temperature and light on biological nitrogenxation in boreal forests.New Phytologist,2012,194(2):453-463.
[27] Whittington H R,Deede L,Powers J S. Growth responses,biomass partitioning,and nitrogen isotopes of prairie legumes in response to elevated temperature and varying nitrogen source in a growth chamber experiment. American Journal of Botany,2012,99(5):838-846.
[28]李军祥,曾辉,朱军涛,张扬建,陈宁,刘瑶杰.藏北高原高寒草甸生态系统呼吸对增温的响应.生态环境学报,2016,25(10):1612-1620.
[29] Dorji T,Totland,Moe S R,Hopping K A,Pan J B,Klein J A. Plant functional traits mediate reproductive phenology and success in response to experimental warming and snow addition in Tibet. Global Change Biology,2013,19(2):459-472.
[30]朱军涛.实验增温对藏北高寒草甸植物繁殖物候的影响.植物生态学报,2016,40(10):1028-1036.
[31] Chen J,Shi W Y,Cao J J. Effects of grazing on ecosystem CO2exchange in a meadow grassland on the Tibetan Plateau during the growing season.Environmental Management,2015,55(2):347-359.
[32] Rudgers J A,Kivlin S N,Whitney K D,Price M V,Waser N M,Harte J. Responses of high-altitude graminoids and soil fungi to 20 years of experimental warming. Ecology,2014,95(7):1918-1928.
[33] Klein J A,Harte J,Zhao X Q. Experimental warming causes large and rapid species loss,dampened by simulated grazing,on the Tibetan Plateau.Ecology Letters,2004,7(12):1170-1179.
[34] Hoeppner S S,Dukes J S. Interactive responses of old-field plant growth and composition to warming and precipitation. Global Change Biology,2012,18(5):1754-1768.
[35] Hutchison J S,Henry H A L. Additive effects of warming and increased nitrogen deposition in a temperate old field:Plant productivity and the importance of winter. Ecosystems,2010,13(5):661-672.
[36] Grime J P. Plant strategies,vegetation processes,and ecosystem properties. Journal of Vegetation Science,2002,13(2):293-395.
[37] Klanderud K,Totland. Simulated climate change altered dominance hierarchies and diversity of an alpine biodiversity hotspot. Ecology,2005,86(8):2047-2054.
[38] Niu S L,Wan S Q. Warming changes plant competitive hierarchy in a temperate steppe in northern China. Journal of Plant Ecology,2008,1(2):103-110.
[39] Flanagan L B,Wever L A,Carlson P J. Seasonal and interannual variation in carbon dioxide exchange and carbon balance in a northern temperate grassland. Global Change Biology,2005,8(7):599-615.
[40]韦梅琴,李军乔.委陵菜属四种植物茎叶解剖结构的比较研究.青海师范大学学报:自然科学版,2003,(3):48-50,54.
[41] Mariotte P. Do subordinate species punch above their weight? Evidence from above-and below-ground. New Phytologist,2014,203(1):16-21.
[42] Vedyushkin M A. Vegetation response to global warming:The role of hysteresis effect. Water,Air,and Soil Pollution,1997,95(1/4):1-12.
[43] Zhang G L,Xu X L,Zhou C P,Zhang H B,Ouyang H. Responses of grassland vegetation to climatic variations on different temporal scales in Hulun Buir Grassland in the past 30 years. Journal of Geographical Sciences,2011,21(4):634-650.
[44] Wang C T,Long R J,Wang Q L,Liu W,Jing Z C,Zhang L. Fertilization and litter effects on the functional group biomass,species diversity of plants,microbial biomass,and enzyme activity of two alpine meadow communities. Plant and Soil,2010,331(1/2):377-389.
[2] Cubasch U,Wuebbles D,Chen D,Facchini M C,Frame D,Mahowald N,Winther J G. Introduction//Climate Change 2013:The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge:Cambridge University Press,2013:741-866.
[3] Chen J,Luo Y Q,Xia J Y,Shi Z,Jiang L F,Niu S L,Zhou X H,Gao J J. Differential responses of ecosystem respiration components to experimental warming in a meadow grassland on the Tibetan Plateau. Agricultural and Forest Meteorology,2016,220:21-29.
[4] Wang S P,Duan J C,Xu P,Wang Y F,Zhang Z H,Rui Y C,Luo C Y,Xu B,Zhu X X,Chang X F,Cui X Y,Niu H S,Zhao X Q,Wang W Y. Effects of warming and grazing on soil N availability,species composition,and ANPP in an alpine meadow. Ecology,2012,93(11):2365-2376.
[5] Yang H J,Wu M Y,Liu W X,Zhang Z,Zhang N L,Wan S Q. Community structure and composition in response to climate change in a temperate steppe. Global Change Biology,2011,17(1):452-465.
[6] Yang Z L,Zhang Q,Su F L,Zhang C H,Pu Z C,Xia J Y,Wan S Q,Jiang L. Daytime warming lowers community temporal stability by reducing the abundance of dominant,stable species. Global Change Biology,2017,23(1):154-163.
[7] Corlett R T. Impacts of warming on tropical lowland rainforests. Trends in Ecology&Evolution,2011,26(11):606-613.
[8] Garcia R A,Cabeza M,Rahbek C,Araújo M B. Multiple dimensions of climate change and their implications for biodiversity. Science,2014,344(6183):1247579.
[9] Seddon A W R,Macias-Fauria M,Long P R,Benz D,Willis K J. Sensitivity of global terrestrial ecosystems to climate variability. Nature,2016,531(7593):229-232.
[10] Oliver T H,Isaac N J B,August T A,Woodcock B A,Roy D B,Bullock J M. Declining resilience of ecosystem functions under biodiversity loss.Nature Communications,2015,6:10122.
[11] Hautier Y,Seabloom E W,Borer E T,Adler P B,Harpole W S,Hillebrand H,Lind E M,Mac Dougall A S,Stevens C J,Bakker J D,Buckley Y M,Chu C J,Collins S L,Daleo P,Damschen E I,Davies K F,Fay P A,Firn J,Gruner D S,Jin V L,Klein J A,Knops J M H,La Pierre K J,Li W,Mc Culley R L,Melbourne B A,Moore J L,O'Halloran L R,Prober S M,Risch A C,Sankaran M,Schuetz M,Hector A.Eutrophication weakens stabilizing effects of diversity in natural grasslands. Nature,2014,508(7497):521-525.
[12] Hautier Y,Tilman D,Isbell F,Seabloom E W,Borer E T,Reich P B. Anthropogenic environmental changes affect ecosystem stability via biodiversity. Science,2015,348(6232):336-340.
[13] Lin D L,Xia J Y,Wan S Q. Climate warming and biomass accumulation of terrestrial plants:A meta-analysis. New Phytologist,2010,188(1):187-198.
[14] Wu Z T,Dijkstra P,Koch G W,Pe1uelas J,Hungate B A. Responses of terrestrial ecosystems to temperature and precipitation change:A metaanalysis of experimental manipulation. Global Change Biology,2011,17(2):927-942.
[15] De Boeck H J,Lemmens C M H M,Gielen B,Bossuyt H,Malchair S,Carnol M,Merckx R,Ceulemans R,Nijs I. Combined effects of climate warming and plant diversity loss on above-and below-ground grassland productivity. Environmental and Experimental Botany,2007,60(1):95-104.
[16] Saleska S R,Shaw M R,Fischer M L,Dunne J A,Still C J,Holman M L,Harte J. Plant community composition mediates both large transient decline and predicted long-term recovery of soil carbon under climate warming. Global Biogeochemical Cycles,2002,16(4):1055.
[17]宗宁,柴曦,石培礼,蒋婧,牛犇,张宪洲,何永涛.藏北高寒草甸群落结构与物种组成对增温与施氮的响应.应用生态学报,2016,27(12):3739-3748.
[18]李娜,王根绪,杨燕,高永恒,柳林安,刘光生.短期增温对青藏高原高寒草甸植物群落结构和生物量的影响.生态学报,2011,31(4):895-905.
[19] Post E,Pedersen C. Opposing plant community responses to warming with and without herbivores. Proceedings of the National Academy of Sciences of the United States of America,2008,105(34):12353-12358.
[20] Hooper D U,Adair E C,Cardinale B J,Byrnes J E K,Hungate B A,Matulich K L,Gonzalez A,Duffy J E,Gamfeldt L,O'Connor M I. A global synthesis reveals biodiversity loss as a major driver of ecosystem change. Nature,2012,486(7401):105-108.
[21] Luo C Y,Xu G P,Chao Z G,Wang S P,Lin X W,Hu Y G,Zhang Z H,Duan J C,Chang X F,Su A L,Li Y N,Zhao X Q,Du M Y,Tang Y H,Kimball B. Effect of warming and grazing on litter mass loss and temperature sensitivity of litter and dung mass loss on the Tibetan plateau.Global Change Biology,2010,16(5):1606-1617.
[22] Niu S L,Wu M Y,Han Y,Xia J Y,Li L H,Wan S Q. Water-mediated responses of ecosystem carbonuxes to climatic change in a temperate steppe. New Phytologist,2008,177(1):209-219.
[23] Rustad L,Campbell J,Marion G,Norby R,Mitchell M,Hartley A,Cornelissen J,Gurevitch J. A meta-analysis of the response of soil respiration,net nitrogen mineralization,and aboveground plant growth to experimental ecosystem warming. Oecologia,2001,126(4):543-562.
[24] Dieleman W I J,Vicca S,Dijkstra F A,Hagedorn F,Hovenden M J,Larsen K S,Morgan J A,Volder A,Beier C,Dukes J S,King J,Leuzinger S,Linder S,Luo Y Q,Oren R,De Angelis P,Tingey D,Hoosbeek M R,Janssens I A. Simple additive effects are rare:a quantitative review of plant biomass and soil process responses to combined manipulations of CO2and temperature. Global Change Biology,2012,18(9):2681-2693.
[25] Ward J Y,Tissue D T,Thomas R B,Strain B R. Comparative responses of model C3and C4plants to drought in low and elevated CO2. Global Change Biology,1999,5(8):857-867.
[26] Gundale M J,Nilsson M,Bansal S,Jderlund A. The interactive effects of temperature and light on biological nitrogenxation in boreal forests.New Phytologist,2012,194(2):453-463.
[27] Whittington H R,Deede L,Powers J S. Growth responses,biomass partitioning,and nitrogen isotopes of prairie legumes in response to elevated temperature and varying nitrogen source in a growth chamber experiment. American Journal of Botany,2012,99(5):838-846.
[28]李军祥,曾辉,朱军涛,张扬建,陈宁,刘瑶杰.藏北高原高寒草甸生态系统呼吸对增温的响应.生态环境学报,2016,25(10):1612-1620.
[29] Dorji T,Totland,Moe S R,Hopping K A,Pan J B,Klein J A. Plant functional traits mediate reproductive phenology and success in response to experimental warming and snow addition in Tibet. Global Change Biology,2013,19(2):459-472.
[30]朱军涛.实验增温对藏北高寒草甸植物繁殖物候的影响.植物生态学报,2016,40(10):1028-1036.
[31] Chen J,Shi W Y,Cao J J. Effects of grazing on ecosystem CO2exchange in a meadow grassland on the Tibetan Plateau during the growing season.Environmental Management,2015,55(2):347-359.
[32] Rudgers J A,Kivlin S N,Whitney K D,Price M V,Waser N M,Harte J. Responses of high-altitude graminoids and soil fungi to 20 years of experimental warming. Ecology,2014,95(7):1918-1928.
[33] Klein J A,Harte J,Zhao X Q. Experimental warming causes large and rapid species loss,dampened by simulated grazing,on the Tibetan Plateau.Ecology Letters,2004,7(12):1170-1179.
[34] Hoeppner S S,Dukes J S. Interactive responses of old-field plant growth and composition to warming and precipitation. Global Change Biology,2012,18(5):1754-1768.
[35] Hutchison J S,Henry H A L. Additive effects of warming and increased nitrogen deposition in a temperate old field:Plant productivity and the importance of winter. Ecosystems,2010,13(5):661-672.
[36] Grime J P. Plant strategies,vegetation processes,and ecosystem properties. Journal of Vegetation Science,2002,13(2):293-395.
[37] Klanderud K,Totland. Simulated climate change altered dominance hierarchies and diversity of an alpine biodiversity hotspot. Ecology,2005,86(8):2047-2054.
[38] Niu S L,Wan S Q. Warming changes plant competitive hierarchy in a temperate steppe in northern China. Journal of Plant Ecology,2008,1(2):103-110.
[39] Flanagan L B,Wever L A,Carlson P J. Seasonal and interannual variation in carbon dioxide exchange and carbon balance in a northern temperate grassland. Global Change Biology,2005,8(7):599-615.
[40]韦梅琴,李军乔.委陵菜属四种植物茎叶解剖结构的比较研究.青海师范大学学报:自然科学版,2003,(3):48-50,54.
[41] Mariotte P. Do subordinate species punch above their weight? Evidence from above-and below-ground. New Phytologist,2014,203(1):16-21.
[42] Vedyushkin M A. Vegetation response to global warming:The role of hysteresis effect. Water,Air,and Soil Pollution,1997,95(1/4):1-12.
[43] Zhang G L,Xu X L,Zhou C P,Zhang H B,Ouyang H. Responses of grassland vegetation to climatic variations on different temporal scales in Hulun Buir Grassland in the past 30 years. Journal of Geographical Sciences,2011,21(4):634-650.
[44] Wang C T,Long R J,Wang Q L,Liu W,Jing Z C,Zhang L. Fertilization and litter effects on the functional group biomass,species diversity of plants,microbial biomass,and enzyme activity of two alpine meadow communities. Plant and Soil,2010,331(1/2):377-389.