沙化草地土壤碳氮磷化学计量特征及其对植被生产力和多样性的影响
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摘要
沙化草地土壤碳(C)、氮(N)、磷(P)化学计量特征及其对植被生产力与多样性的影响对于认识草地沙漠化过程中土壤与植被的互馈关系,以及沙漠化发展的生态学机理具有重要的意义。通过对科尔沁沙地75个沙化样地的野外调查,研究了科尔沁沙地不同程度沙化草地的表层土壤C、N、P化学计量特征及其与生产力和多样性的相关关系。结果表明:1)科尔沁沙地沙化草地表层土壤具有较低的有机C、全N、全P含量及C∶N、N∶P和C∶P,平均值分别为1.39 mg/g、0.117 mg/g、0.079 mg/g和7.50、2.22、16.91;草地沙漠化过程中,土壤有机C、全N、全P含量显著降低的同时,C∶N、N∶P和C∶P亦显著降低,表明土壤有机C、全N、全P在沙漠化过程中的损失是不同步的;2)科尔沁沙地沙化草地表层土壤有机C、全N、全P元素间均呈显著正相关,具有一定的耦合关系,且土壤有机C和全P间的耦合关系不随沙漠化的发展而发生改变;3)草地沙化过程中,土壤养分的损失限制着草地生产力,而土壤N∶P较全N、全P含量更能反映土壤养分对生产力的限制作用;4)沙化草地土壤全N含量与物种丰富度间具有显著正相关关系,而土壤全P含量与其无显著相关性;多样性指数与全N、全P含量间均具有显著正相关关系;相对于土壤全N、全P含量,N∶P能更好地反映养分平衡对物种多样性的影响作用。
Information on the stoichiometry of carbon(C), nitrogen,(N) and phosphorus(P) in soils and its effects on community productivity and species richness in desertified grassland is essential to understanding the interactive relationship between soil and vegetation in the process of grassland desertification, and reveals the ecological mechanisms of land desertification. In this study, we measured organic C, total N, total P concentrations, and C∶N, N∶P, C∶P in the topsoil of different desertified grasslands in the Horqin sandy land, and statistically analyzed the correlations among C, N, and P stoichiometry, community productivity, and species diversity. The results showed that the concentrations of organic C(1.39 mg/g), total N(0.117 mg/g), and total P(0.079 mg/g), and the C∶N(7.50), N∶P(2.22), and C∶P(16.91) ratios in the topsoil of desertified grasslands remained at relatively low levels in contrast to the results nationwide or worldwide. It was not surprising that soil C, N, and P significantly decreased during grassland desertification. Their ratios, however, also significantly decreased in the gradient of desertification, suggesting an asynchronous loss of soil C, N, and P in the process of desertification. We found that topsoil organic C, total N, total P, and their ratios were positively correlated, suggesting a coupling relationship among organic C, total N, and total P in topsoil in the study sites. Further, the coupling relationships between organic C and total P did not change with the development of grassland desertification. Expectedly, community productivity was limited by the loss of soil nutrients in desertified grassland in this study. However, soil N∶P stoichiometry could explain more variations of community productivity than soil N or P concentration could. Similarly, correlation analysis showed that species richness was significantly correlated with soil N, but not P. The diversity index was significantly correlated with soil N and P. Compared with N or P concentration, the soil N∶P stoichiometry effectively reflected the influence of nutrient balance on species diversity.
Information on the stoichiometry of carbon(C), nitrogen,(N) and phosphorus(P) in soils and its effects on community productivity and species richness in desertified grassland is essential to understanding the interactive relationship between soil and vegetation in the process of grassland desertification, and reveals the ecological mechanisms of land desertification. In this study, we measured organic C, total N, total P concentrations, and C∶N, N∶P, C∶P in the topsoil of different desertified grasslands in the Horqin sandy land, and statistically analyzed the correlations among C, N, and P stoichiometry, community productivity, and species diversity. The results showed that the concentrations of organic C(1.39 mg/g), total N(0.117 mg/g), and total P(0.079 mg/g), and the C∶N(7.50), N∶P(2.22), and C∶P(16.91) ratios in the topsoil of desertified grasslands remained at relatively low levels in contrast to the results nationwide or worldwide. It was not surprising that soil C, N, and P significantly decreased during grassland desertification. Their ratios, however, also significantly decreased in the gradient of desertification, suggesting an asynchronous loss of soil C, N, and P in the process of desertification. We found that topsoil organic C, total N, total P, and their ratios were positively correlated, suggesting a coupling relationship among organic C, total N, and total P in topsoil in the study sites. Further, the coupling relationships between organic C and total P did not change with the development of grassland desertification. Expectedly, community productivity was limited by the loss of soil nutrients in desertified grassland in this study. However, soil N∶P stoichiometry could explain more variations of community productivity than soil N or P concentration could. Similarly, correlation analysis showed that species richness was significantly correlated with soil N, but not P. The diversity index was significantly correlated with soil N and P. Compared with N or P concentration, the soil N∶P stoichiometry effectively reflected the influence of nutrient balance on species diversity.
引文
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[30]王常慧,邢雪荣,韩兴国.草地生态系统中土壤氮素矿化影响因素的研究进展.应用生态学报,2004,15(11):2184-2188.
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[32]文海燕,赵哈林.退化沙质草地植被与土壤分布特征及相关分析.干旱区研究,2004,21(1):76-80.
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[2]N?sholm T,Ekblad A,Nordin A,Giesler R,H?gberg M,H?gberg P.Boreal forest plants take up organic nitrogen.Nature,1998,392(6679):914-916.
[3]Dormaar J F,Smoliak S,Willms W D.Distribution of nitrogen fractions in grazed and ungrazed fescue grassland Ah horizons.Journal of Range Management,1990,43(1):6-9.
[4]王绍强,于贵瑞.生态系统碳氮磷元素的生态化学计量学特征.生态学报,2008,28(8):3937-3947.
[5]苏永中,赵哈林,文海燕.退化沙质草地开垦和封育对土壤理化性状的影响.水土保持学报,2002,16(4):5-8.
[6]孙小丽,康萨如拉,张庆,常昌明,马文静,牛建明.荒漠草原物种多样性、生产力与气候因子和土壤养分之间关系的研究.草业学报,2015,24(12):10-19.
[7]石红霄,侯向阳,师尚礼,吴新宏,李鹏,杨婷婷.高山嵩草草甸初级生产力、多样性与土壤因子的关系.草业学报,2015,24(10):40-47.
[8]左小安,赵学勇,赵哈林,李玉强,郭轶瑞,赵玉萍.科尔沁沙质草地群落物种多样性、生产力与土壤特性的关系.环境科学,2007,28(5):945-951.
[9]Li Y Q,Zhou X H,Brandle J R,Zhang T H,Chen Y P,Han J J.Temporal progress in improving carbon and nitrogen storage by grazing exclosure practice in a degraded land area of China's Horqin Sandy Grassland.Agriculture,Ecosystems&Environment,2012,159:55-61.
[10]Zhang T H,Zhao H L,Li S G,Li F R,Shirato R,Ohkuro T,Taniyama I.A comparison of different measures for stabilizing moving sand dunes in the Horqin Sandy Land of Inner Mongolia,China.Journal of Arid Environments,2004,58(2):203-214.
[11]李玉强,赵哈林,赵学勇,云建英,刘新平.沙漠化过程对植物凋落物分解的影响.水土保持学报,2007,21(5):64-67.
[12]朱震达,陈广庭.中国土地沙质荒漠化.北京:科学出版社,1994:23-26.
[13]王绍强,周成虎,李克让,朱松丽,黄方红.中国土壤有机碳库及空间分布特征分析.地理学报,2000,55(5):533-544.
[14]Tian H Q,Chen G S,Zhang C,Melillo J M,Hall C A S.Pattern and variation of C∶N∶P ratios in China's soils:a synthesis of observational data.Biogeochemistry,2010,98(1/3):139-151.
[15]陶冶,吴甘霖,刘耀斌,张元明.古尔班通古特沙漠典型灌木群落土壤化学计量特征及其影响因素.中国沙漠,2017,37(2):305-314.
[16]李玉强,赵哈林,移小勇,左小安,陈银萍.沙漠化过程中科尔沁沙地植物-土壤系统碳氮储量动态.环境科学,2006,27(4):635-640.
[17]Cleveland C C,Liptzin D.C∶N∶P stoichiometry in soil:is there a"Redfield ratio"for the microbial biomass?Biogeochemistry,2007,85(3):235-252.
[18]林丽,李以康,张法伟,杜岩功,郭小伟,李婧,刘淑丽,曹广民.高寒矮嵩草群落退化演替系列氮、磷生态化学计量学特征.生态学报,2013,33(17):5245-5251.
[19]罗亚勇,孟庆涛,张静辉,赵学勇,秦彧.青藏高原东缘高寒草甸退化过程中植物群落物种多样性、生产力与土壤特性的关系.冰川冻土,2014,36(5):1298-1305.
[20]阿依敏·波拉提,安沙舟,董乙强,张爱宁,杨娇.巴音布鲁克高寒草原不同退化阶段土壤养分的变化.新疆农业科学,2017,54(5):953-960.
[21]赵哈林,周瑞莲,苏永中,张继义,移小勇.我国北方半干旱地区土壤的沙漠化演变过程与机制.水土保持学报,2007,21(3):1-5.
[22]卢红梅,王世杰.喀斯特石漠化过程中的土壤物理组分有机碳氮研究.水土保持通报,2009,29(5):50-55.
[23]Lorenz R D,Mitchell K L,Kirk R L,Hayes A G,Aharonson O,Zebker H A,Paillou P,Radebaugh J,Lunine J I,Janssen M A,Wall S D,Lopes R M,Stiles B,Ostro S,Mitri G,Stofan E R.Titan's inventory of organic surface materials.Geophysical Research Letters,2008,35(2):L02206.
[24]朱秋莲,程曼,安韶山,薛志婧.宁南山区植被恢复对土壤团聚体特征及腐殖质分布的影响.水土保持学报,2013,27(4):247-251.
[25]Zhang Z S,Xue Z S,Lyu X G,Tong S Z,Jiang M.Scaling of soil carbon,nitrogen,phosphorus and C∶N∶P ratio patterns in peatlands of China.Chinese Geographical Science,2017,27(4):507-515.
[26]Sterner R W,Elser J J.Ecological Stoichiometry:The Biology of Elements from Molecules to the Biosphere.Princeton,NJ:Princeton University Press,2002:225-226.
[27]Sinsabaugh R L,Antibus R K,Linkins A E,Mc Claugherty C A,Rayburn L,Repert D,Weiland T.Wood decomposition:nitrogen and phosphorus dynamics in relation to extracellular enzyme activity.Ecology,1993,74(5):1586-1593.
[28]Christensen B T.Physical fractionation of soil and organic matter in primary particle size and density separates//Stewart B A,ed.Advances in Soil Science.New York:Springer,1992:1-90.
[29]苏永中,赵哈林,张铜会,赵学勇.不同退化沙地土壤碳的矿化潜力.生态学报,2004,24(2):372-378.
[30]王常慧,邢雪荣,韩兴国.草地生态系统中土壤氮素矿化影响因素的研究进展.应用生态学报,2004,15(11):2184-2188.
[31]展鹏飞,肖德荣,闫鹏飞,刘振亚,马金成,陈志明,格茸,田伟,王行.藏猪扰动作用下的高寒草甸土壤退化特征及微生物群落结构变化.环境科学,2018,39(4):1840-1850.
[32]文海燕,赵哈林.退化沙质草地植被与土壤分布特征及相关分析.干旱区研究,2004,21(1):76-80.
[33]Gross K L,Pregitzer A J,Burton A J.Spatial variation in nitrogen availability in three successional plant communities.Journal of Ecology,1995,83(3):357-367.
[34]Wassen M J,Olde Venterink H G M,De Swart E O A M.Nutrient concentrations in mire vegetation as a measure of nutrient limitation in mire ecosystems.Journal of Vegetation Science,1995,6(1):5-16.
[35]张林静,岳明,顾峰雪,张远东,潘晓玲,赵桂仿.新疆阜康绿洲荒漠过渡带植物群落物种多样性与土壤环境因子的耦合关系.应用生态学报,2002,13(6):658-662.
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