摘要
畜粪是广大牧区可稳定获得的主要生活能源。长期、大量地把畜粪移出草地生态系统阻断了物质循环,致使土壤肥力变差、草地初级生产力下降、增加了草地生态系统物质循环紊乱的风险。与畜粪自然分解相比,畜粪燃能利用加速了碳排放,对放牧草地生态系统的碳循环产生了明显影响。本研究依托中科院地理资源所当雄草原生态站,综合运用3S技术、牧户调查、样方调查、实验分析和模型模拟等方法,基于藏北牧区的草地、牲畜、畜粪利用的地带性规律,重点从草地初级生产力、土壤呼吸、畜粪土壤碳回归、畜粪燃烧碳排放等4个关键环节,研究畜粪能源利用对草地生态系统碳循环的影响机制及其碳平衡过程,为畜粪资源优化利用、生态环境保护和增汇减排提供决策支持。
There are two yak dung utilization pattern in north Tibetan,one is all dung remain in rangeland and return to soil to supplement the organic carbon and nutrition in soil and the other is dung removing out of grassland ecosystem and combusting as fuel.Comparing with the dung back to soil situation,dung combustion changes the carbon cycle and carbon balance in the grazing alpine meadow ecosystem.Consideration of dung combusted for energy,the net biome production（NBP）of the energy-grazing alpine meadow ecosystem can be accounted by adding the carbon import（dung production）to,while subtracting carbon export（livestock intake,dung combusted and dung respiration）from NEP（NEP=NPP-Rs）.In order to depict the key stage of the carbon cycle of the alpine meadow,indicators were measured by various methods,for examples,with plot survey to get the data of biomass and NPP,the LI-8100 CO2 flux system（LI-COR Inc.,Lincon,NE,USA）used to measure the soil respiration（Rs）,and application with household interview to get the data of yak dung（Dt,De）.The yak intake（Gi）and dung respiration（Rd）is estimated by modeling.At presently,about 82.6%of yak dung was combusted for resident energy in north Tibetan.Impact of dung combustion on carbon cycle of alpine meadow ecosystem lies in：1）The direct effect is dung-derived carbon emission to atmosphere increase and that back to soil decrease.In the situation of dung combusted as fuel,the dung-derived C emission from both the process of dung heterotrophic respiration and dung combustion reached 10.09 gC/m2.a,which was 6.64 gC/m.2a more than that in the situation of dung back to soil.Correspondingly,the dung-derived C backt o soil is only 1.40 gC/m2.a,6.64 gC/m 2.a less than that in the situation of dung back to soil;2）The indirect effect is the primary production decrease for the soil infertile via dung removing out the ecosystem.The carbon captured by vegetation was only 304.33 gC/m2.a,which was 49.67 gC/m 2.a less than that in the situation of dung back to soil;3）The induce effect of the primary production decrease is the reduction of soil respiration of the alpine meadow ecosystem.The soil respiration was 284.67 gC/m.2a,which was 11 gC/m 2.a less than that in the situation of dung back to soil;4）The general effect of dung combustion on C cycle of the alpine meadow ecosystem can be illustrated as the NBP.The NBP dropped to-17.24 gC/m.2a in the situation of dung combustion,w hich was 45.32 gC/m2.a less than that in the situation of dung back to soil.The carbon sequestration and storage capacity including the C dung-derived stored in soil and C captured by vegetation,were decreased remarkably.It is indicated that the energy-grazing alpine meadow ecosystem is a kind of net carbon source,which may affect climate change profoundly.In order to prevent grassland ecosystem from deterioration and reduce C emission,it’s necessary to lessen the proportion of dung combustion,while increase that of back to soil to maintain soil fertile and C cycle successfully.
出处
《资源科学》
CSSCI
CSCD
北大核心
2012年第6期1062-1069,共8页
Resources Science
基金
中国科学院地理科学与资源研究所知识创新项目:"生态系统服务供给和消费研究"(编号:200905010)
中国科学院地理资源所知识创新项目:"藏北牧区畜粪能源利用对草地生态系统碳平衡的影响"(编号:201003016)
