短花针茅荒漠草原生态系统净碳交换对载畜率的响应
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摘要
草地生态系统作为中国最大的陆地生态系统,其碳循环的动态变化在全球碳收支平衡中扮演着重要角色。为探讨短花针茅(Stipa breviflora)荒漠草原净CO_2交换的日变化和季节变化特征,阐明放牧及土壤温度和湿度的季节性变化对生态系统净CO_2交换的影响,采用便携式光合仪LI-6400(LI-COR,USA)和密闭式箱法于2013—2014年生长季(5—10月)测定了对照(CK)、轻牧(LG)、中牧(MG)和重度放牧(HG)4个处理的生态系统净碳交换。结果表明:短花针茅荒漠草原净CO_2交换具有明显的日变化规律。净碳交换的日动态主要受气温影响,昼间净碳吸收随温度升高而降低,甚至出现碳释放;夜间随气温降低,生态系统呼吸减弱。整个生长季,短花针茅荒漠草原表现为碳汇,在植物生长季的高峰期,净碳吸收达到峰值(-2.96mol·m~(-2)·s~(-1))。年际间生态系统净碳交换差异显著(P<0.000 1),净碳交换主要受降水调控。净碳吸收与土壤温度在两年间均呈显著的二次多项式关系(P<0.01),而与土壤湿度的关系则是2013年为显著的线性关系(P<0.000 1),2014年为显著的二次多项式关系(P<0.01)。土壤温度对生态系统净CO_2交换变化的解释能力为0.31~0.36,而土壤湿度对生态系统净CO_2交换变化的解释能力为0.26~0.51。HG区净碳吸收速率(-0.66mol·m~(-2)·s~(-1))显著低于CK区(-1.65mol·m~(-2)·s~(-1))。放牧减弱了荒漠草原的固碳潜力。
To explore the diurnal and seasonal dynamics of net CO_2 exchange characteristics of Stipa Breviflora desert steppe, and to clarify the effects of grazing and seasonal variations of soil temperature and moisture on net ecosystem CO_2 exchange, we used portable optical LI-6400(LI-COR, USA) and the method of static chamber to measure net ecosystem carbon exchange under the four stocking rate treatments(control-CK, lightly grazing-LG, moderately grazing-MG, heavily grazing-HG) during the growing season(from May to October) of 2013 and 2014. During this period, we also measured soil temperature and soil moisture at a depth of 10 cm twice per month. Diurnal dynamics of net carbon exchange was measured once per month in July and August on sunny days. We found that the diurnal dynamics of net CO_2 exchange of Stipa breviflora desert steppe was related to air temperature. During the day, net carbon absorption decreased with increasing temperature, and even carbon release occurred. As the temperature decreased at night, ecosystem respiration decreased. Throughout the growing season, Stipa breviflora desert steppe acted as carbon source, only moderately and heavily grazing plots had a slight carbon release in June. When biomass reached peak, net carbon gain was the highest(-2.96mol·m~(-2)·s~(-1)). Year significantly affected net ecosystem CO_2 uptake(P<0.0001). Net carbon exchange was mainly controlled by precipitation. There was a significant quadratic polynomial relationship between net CO_2 exchange and soil temperature in 2013 and 2014(P<0.01). A significant linear relationship was found between net CO_2 exchange and soil moisture in 2013(P<0.0001), and a significant quadratic polynomial relationship in 2014(P<0.01). The influence of soil temperature soil temperature on net ecosystem CO_2 exchange was 0.31~0.36, while soil moisture on the change of net ecosystem CO_2 exchange was 0.26~0.51. The net carbon uptake rate in HG block(-0.66mol·m~(-2)·s~(-1)) was significantly lower than that in CK block(-1.65mol·m~(-2)·s~(-1)). Therefore, grazing can reduce carbon sequestration potential of desert steppe.
To explore the diurnal and seasonal dynamics of net CO_2 exchange characteristics of Stipa Breviflora desert steppe, and to clarify the effects of grazing and seasonal variations of soil temperature and moisture on net ecosystem CO_2 exchange, we used portable optical LI-6400(LI-COR, USA) and the method of static chamber to measure net ecosystem carbon exchange under the four stocking rate treatments(control-CK, lightly grazing-LG, moderately grazing-MG, heavily grazing-HG) during the growing season(from May to October) of 2013 and 2014. During this period, we also measured soil temperature and soil moisture at a depth of 10 cm twice per month. Diurnal dynamics of net carbon exchange was measured once per month in July and August on sunny days. We found that the diurnal dynamics of net CO_2 exchange of Stipa breviflora desert steppe was related to air temperature. During the day, net carbon absorption decreased with increasing temperature, and even carbon release occurred. As the temperature decreased at night, ecosystem respiration decreased. Throughout the growing season, Stipa breviflora desert steppe acted as carbon source, only moderately and heavily grazing plots had a slight carbon release in June. When biomass reached peak, net carbon gain was the highest(-2.96mol·m~(-2)·s~(-1)). Year significantly affected net ecosystem CO_2 uptake(P<0.0001). Net carbon exchange was mainly controlled by precipitation. There was a significant quadratic polynomial relationship between net CO_2 exchange and soil temperature in 2013 and 2014(P<0.01). A significant linear relationship was found between net CO_2 exchange and soil moisture in 2013(P<0.0001), and a significant quadratic polynomial relationship in 2014(P<0.01). The influence of soil temperature soil temperature on net ecosystem CO_2 exchange was 0.31~0.36, while soil moisture on the change of net ecosystem CO_2 exchange was 0.26~0.51. The net carbon uptake rate in HG block(-0.66mol·m~(-2)·s~(-1)) was significantly lower than that in CK block(-1.65mol·m~(-2)·s~(-1)). Therefore, grazing can reduce carbon sequestration potential of desert steppe.
引文
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CHEN S P,LIN G H,HUANG J H,et al.2009.Dependence of carbon sequestration on the differential responses of ecosystem photosynthesis and respiration to rain pulses in a semiarid steppe[J].Global Change Biology,15(10):2450-2461.
DUGAS W A,HEUER M L,MAYEUX H S.1999.Carbon dioxide fluxes over Bermuda grass,native prairie,and sorghum[J].Agricultural and Forest Meteorology,93(2):121-139.
FLANAGAN L B,WEVER L A,CARLSON P J.2002.Seasonal and interannual variation in carbon dioxide exchange and carbon balance in a northern temperate grassland[J].Global Change Biology,8(7):599-615.
FRANK A B.2002.Carbon dioxide fluxes over a grazed prairie and seeded pasture in the Northern Great Plains[J].Environmental Pollution,116(3):397-403.
KIM JOON,VERMA S B.1990.Carbon dioxide exchange in a temperate grassland ecosystem[J].Bound Layer Meteorology,52(1):135-149.
MA S Y,BALDOCCHI D D,XU L K,et al.2007.Inter-annual variability in carbon dioxide exchange of an oak/grass savanna and open grassland in California[J].Agricultural and Forest Meteorology,147(3-4):157-171.
NIEVEEN J P,CAMPBELL D I,SCHIPPER L A,et al.2005.Carbon exchange of grazed pasture on a drained peat soil[J].Global Change Biology,11(4):607-618.
OATES L G,JACKSON R D.2014.Livestock Management Strategy Affects Net Ecosystem Carbon Balance of Subhumid Pasture[J].Rangeland Ecology and Management,67(1):19-29.
XU L K,BALDOCCHI D.2004.Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California[J].Agricultural and Forest Meteorology,123(1-2):79-96.
ZHOU X H,WAN S Q,LUO Y Q.2007.Source components and interannual variability of soil CO2 efflux under experimental warming and clipping in a grassland ecosystem[J].Global Change Biology,13(4):761-775.
董云社,章申,齐玉春,等.2000.内蒙古典型草地CO2,N2O,CH4通量的同时观测及其日变化[J].科学通报,45(3):318-322.
杜群,刘辉志,冯健武,等.2012.半干旱区草原生态系统的碳交换特征[J].中国科学:地球科学,42(5):711-722.
丁娓,孙霞,贾阳阳,等.2014.不同放牧强度对天山北坡草原草地生态系统碳交换速率的影响[J].新疆农业大学学报,37(03):197-202.
韩国栋,焦树英,毕力格图,等.2007.短花针茅草原不同载畜率对植物多样性和草地生产力的影响[J].生态学报,27(1):182-188.
胡毅,朱新萍,贾宏涛,等.2017.围栏封育对天山北坡草甸草原生态系统碳交换的影响[J/OL].植物生态学报,doi:10.17521/cjpe.2016.0049.
韩其飞,罗格平,李超凡,等.2014.基于Biome-BGC模型的天山北坡森林生态系统碳动态模拟[J].干旱区研究,31(03):375-382.
李冰,葛世栋,徐田伟,等.2014.放牧强度对青藏高原高寒草甸净生态系统交换量的影响[J].草业科学,31(7):1203-1210.
李峰,李琪,薛红喜,等.2012.温度对克氏针茅草原生态系统生长季碳通量的影响[J].农业环境科学学报,31(7):1453-1459.
王雷,刘辉志,Ketzer Bettina,等.2009.放牧强度对内蒙古半干旱草原地气间能量和物质交换的影响[J].大气科学,33(6):1201-1211.
王忠美.2016.放牧和开垦对温带典型草原CO2通量的影响[D].北京:中国农业大学.
卫智军,韩国栋,杨静,等.2000.短花针茅荒漠草原植物群落特征对不同载畜率水平的响应(英文)[J].中国草地,(6):2-6.
徐玲玲,张宪洲,石培礼,等.2005.青藏高原高寒草甸生态系统净二氧化碳交换量特征[J].生态学报,25(8):1948-1952.
徐世晓,赵新全,李英年,等.2004.青藏高原高寒灌丛生长季和非生长季CO2通量分析[J].中国科学(D辑:地球科学),S2:118-124.
张新杰.2015.短花针茅荒漠草原生态系统碳交换对不同载畜率的响应[D].呼和浩特:内蒙古农业大学.
赵海军,卫智军,刘泽东,等.2006.绵羊牧食行为及其与植物群落斑块关系的研究[J].内蒙古草业,18(2):12-15.
周文昌,索郎夺尔基,崔丽娟,等.2015.围栏禁牧与放牧对若尔盖高原泥炭地CO2和CH4排放的影响[J].生态环境学报,24(2):183-189.
朱二雄.2016.不同放牧强度对高寒草甸CO2排放通量的影响[D].咸阳:西北农林科技大学.
CHEN S P,LIN G H,HUANG J H,et al.2009.Dependence of carbon sequestration on the differential responses of ecosystem photosynthesis and respiration to rain pulses in a semiarid steppe[J].Global Change Biology,15(10):2450-2461.
DUGAS W A,HEUER M L,MAYEUX H S.1999.Carbon dioxide fluxes over Bermuda grass,native prairie,and sorghum[J].Agricultural and Forest Meteorology,93(2):121-139.
FLANAGAN L B,WEVER L A,CARLSON P J.2002.Seasonal and interannual variation in carbon dioxide exchange and carbon balance in a northern temperate grassland[J].Global Change Biology,8(7):599-615.
FRANK A B.2002.Carbon dioxide fluxes over a grazed prairie and seeded pasture in the Northern Great Plains[J].Environmental Pollution,116(3):397-403.
KIM JOON,VERMA S B.1990.Carbon dioxide exchange in a temperate grassland ecosystem[J].Bound Layer Meteorology,52(1):135-149.
MA S Y,BALDOCCHI D D,XU L K,et al.2007.Inter-annual variability in carbon dioxide exchange of an oak/grass savanna and open grassland in California[J].Agricultural and Forest Meteorology,147(3-4):157-171.
NIEVEEN J P,CAMPBELL D I,SCHIPPER L A,et al.2005.Carbon exchange of grazed pasture on a drained peat soil[J].Global Change Biology,11(4):607-618.
OATES L G,JACKSON R D.2014.Livestock Management Strategy Affects Net Ecosystem Carbon Balance of Subhumid Pasture[J].Rangeland Ecology and Management,67(1):19-29.
XU L K,BALDOCCHI D.2004.Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California[J].Agricultural and Forest Meteorology,123(1-2):79-96.
ZHOU X H,WAN S Q,LUO Y Q.2007.Source components and interannual variability of soil CO2 efflux under experimental warming and clipping in a grassland ecosystem[J].Global Change Biology,13(4):761-775.
董云社,章申,齐玉春,等.2000.内蒙古典型草地CO2,N2O,CH4通量的同时观测及其日变化[J].科学通报,45(3):318-322.
杜群,刘辉志,冯健武,等.2012.半干旱区草原生态系统的碳交换特征[J].中国科学:地球科学,42(5):711-722.
丁娓,孙霞,贾阳阳,等.2014.不同放牧强度对天山北坡草原草地生态系统碳交换速率的影响[J].新疆农业大学学报,37(03):197-202.
韩国栋,焦树英,毕力格图,等.2007.短花针茅草原不同载畜率对植物多样性和草地生产力的影响[J].生态学报,27(1):182-188.
胡毅,朱新萍,贾宏涛,等.2017.围栏封育对天山北坡草甸草原生态系统碳交换的影响[J/OL].植物生态学报,doi:10.17521/cjpe.2016.0049.
韩其飞,罗格平,李超凡,等.2014.基于Biome-BGC模型的天山北坡森林生态系统碳动态模拟[J].干旱区研究,31(03):375-382.
李冰,葛世栋,徐田伟,等.2014.放牧强度对青藏高原高寒草甸净生态系统交换量的影响[J].草业科学,31(7):1203-1210.
李峰,李琪,薛红喜,等.2012.温度对克氏针茅草原生态系统生长季碳通量的影响[J].农业环境科学学报,31(7):1453-1459.
王雷,刘辉志,Ketzer Bettina,等.2009.放牧强度对内蒙古半干旱草原地气间能量和物质交换的影响[J].大气科学,33(6):1201-1211.
王忠美.2016.放牧和开垦对温带典型草原CO2通量的影响[D].北京:中国农业大学.
卫智军,韩国栋,杨静,等.2000.短花针茅荒漠草原植物群落特征对不同载畜率水平的响应(英文)[J].中国草地,(6):2-6.
徐玲玲,张宪洲,石培礼,等.2005.青藏高原高寒草甸生态系统净二氧化碳交换量特征[J].生态学报,25(8):1948-1952.
徐世晓,赵新全,李英年,等.2004.青藏高原高寒灌丛生长季和非生长季CO2通量分析[J].中国科学(D辑:地球科学),S2:118-124.
张新杰.2015.短花针茅荒漠草原生态系统碳交换对不同载畜率的响应[D].呼和浩特:内蒙古农业大学.
赵海军,卫智军,刘泽东,等.2006.绵羊牧食行为及其与植物群落斑块关系的研究[J].内蒙古草业,18(2):12-15.
周文昌,索郎夺尔基,崔丽娟,等.2015.围栏禁牧与放牧对若尔盖高原泥炭地CO2和CH4排放的影响[J].生态环境学报,24(2):183-189.
朱二雄.2016.不同放牧强度对高寒草甸CO2排放通量的影响[D].咸阳:西北农林科技大学.