高寒草地不同利用方式对植被生物量和土壤氮矿化的影响

摘要

研究了天然草地、恢复草地和人工燕麦3种不同草地利用方式植被生物量与土壤氮矿化的变化。结果表明：3种土地利用方式,地上生物量大小依次为恢复草地>燕麦>天然草地,分别为424.02,381.72和307.26 g/m2,地下生物量主要集中在0~10 cm 土层,为天然草地>恢复草地>燕麦,总生物量地下地上比的大小也是天然草地>恢复草地>燕麦；植物种类及扰动大小是3种草地利用方式生物量差异的主要原因。随草地利用方式变化,植被构成、生物量发生变化,土壤氮素矿化作用也随之改变。3种草地利用方式,土壤净氮矿化速率大小为恢复草地>天然草地>燕麦。土壤氮矿化以硝化作用为主,硝态氮是形成生物量的有效氮素。天然草地的地下生物量最大,与其土壤净硝化速率最高有关,燕麦的土壤净氮矿化速率为负值,为植物生长提供的氮素较少,使其生物量最小。%The alpine grasslands under different land use patterns (natural alpine meadow grazed in winter, abandoned cropland under restoration and oat pasture)were selected to study the variation of biomass and soil nitrogen mineralization.The results showed that the order of aboveground biomass was abandoned cropland (424.02 g/m2 )>oat pasture (381.72 g/m2 )> natural alpine meadow (307.26 g/m2 ),and it was natural alpine meadow > abandoned cropland > oat pasture for underground biomass which mainly concentrated within 0 to 10 cm soil layer.The plant species composition,biomass and nitrogen mineralization varied with the land use patterns.The order of soil net nitrogen mineralization rate was abandoned cropland > natural alpine meadow >oat pasture.The nitrification was an important role in soil nitrogen mineralization.