牧草种类与耕作时间对拉萨牧草种植地土壤不同组分有机碳的影响  

Effects of grassland species identity and cultivation time on organic carbon in cultivated soil in Lhasa,Tibet,China

作　　者：蒋婧[1,2] 王沫竹 宋明华[1] 石培礼[1] 宗宁[1,2] 

机构地区：[1]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室、拉萨高原生态试验站,北京100101 [2]中国科学院大学,北京100049 [3]北京林业大学林学院,北京100083

出　　处：《生态学报》2015年第2期424-433,共10页Acta Ecologica Sinica

基　　金：国家基础研究计划973项目(2010CB951704);中国科学院地理科学与资源研究所2010年度资助部署创新项目(201003012);中国科学院地理科学与资源研究所优秀青年人才基金项目(2011RC101)

摘　　要：以中国科学院拉萨高原生态试验站附近天然灌丛草原与站内的牧草种植地为研究对象,分析牧草种类与耕作时间对牧草种植地土壤有机碳的影响。种植地的5种牧草种类为:耕作10a的鸭茅(Dactylis glomerata L.)、耕作4a与10a的垂穗披碱草(Elymus nutans Griseb.)、耕作3a与10a的苜蓿(Medicago sativa Linn.),同时以该区域原生植被天然灌丛草原生长地作为对照。结果表明:与天然灌丛土壤全土有机碳(Total Organic Carbon,TOC)含量相比,耕作10a的鸭茅增加了土层0—5 cm与10—30 cm TOC含量、耕作10a的苜蓿与垂穗披碱草分别显著增加与降低了土层0—5 cm TOC含量。主要因为耕作不同牧草使种植地土壤不同组分有机碳含量发生变化,耕作10a的鸭茅和苜蓿分别使土层0—5 cm与10—30 cm、土层0—5 cm与10—20 cm的砂粒级(50—2000μm)颗粒有机碳(POC)含量降低,粉粒与黏粒级(<50μm)矿物结合态有机碳(MOC)含量升高;耕作10a的垂穗披碱草则使土壤表层0—5 cm砂粒级POC含量显著降低,MOC无显著变化。与耕作4a的垂穗披碱草相比,耕作10a显著降低了土层10—20 cm TOC含量,主要体现在粗砂粒(250—2000μm)POC含量与粉粒(2—50μm)MOC含量的降低;与耕作3a的苜蓿相比,耕作10a的苜蓿显著降低了土层5—30 cm TOC含量,主要因为各土层砂粒级POC含量、粉粒与细黏粒MOC含量均有所降低。说明短期耕作更有利于牧草种植地土壤有机碳库的累积。Effects of grassland species identity and cultivation time on soil organic carbon were studied in cultivated soil in Lhasa National Ecological Research Station, Chinese Academy of Sciences in Tibet, China. Soil samples were collected from one type of local original montane shrub soil （control） and five types of cultivated soil with different grassland species and cultivation time, i.e. one type of Dactylis glomerata L. soil having been cultivated for 10 years （D10）, two types of Elymus nutans Griseb. soil having been cultivated for 4 and 10 years （ E4 and El0） , and two types of Medicago sativa Linn. soil having been cultivated for 3 and 10 years （ M3 and M10 ）. Compared with the control （ the montane shrub soil ）, D10 significantly increased total organic carbon （TOC） in soil at both 0--5 cm and 10--30 cm, but did not significantly affect it in soil at 5--10 cm. El0 significantly decreased TOC in soil at 0--5 cm, and M10 significantly increased TOC in soil at both 0--5 cm and 10--20 cm. All these differences in TOC resulted from different responses of organic carbon in soil fractions to species identity and cultivation time. In D10, particulate organic carbon （POC） of coarse sand （250--2000 μm） decreased and mineral-associated organic carbon （MOC） of silt and clay （〈50 μm） increased in soil depths of 0--5 cm and 10--30 cm compared to the control. El0 significantly reduced POC of sand （50--2000 μm） and MOC of coarse clay （0.2--2 μm） in soil depth of 0--5 cm, but increased MOC of fine clay （〈0.2 μm） at the same soil depth. In M10, POC of coarse sand （250--2000 μm） decreased and MOC of silt （2--50 μm） increased in soil depth of 0--5 cm. In addition, in soil of 10--20 cm in M10, POC of coarse sand （250--2000 μm） decreased, but POC of fine sand （50--250 μm）, MOC of silt （2--50 μm） and MOC of fine clay （〈0.2 μm） increased. Compared to E4, El0 significantly decreased TOC in soil of 10--20 cm. And El0 reduced POC of coarse sand

关 键 词：牧草种类 耕作时间 土壤有机碳 种植地土壤 灌丛土壤 

分 类 号：S812.2[农业科学—草业科学]