高CO2浓度和土壤干旱对贝加尔针茅C,N积累和分配的影响

贝加尔针茅是我国内蒙古草原和东北松嫩平原草地生态系统中的主要植物群落。本文通过模拟大气中CO2浓度升高和土壤干旱研究了贝加尔针茅C，N的积累及分配的影响。结果表明：CO2浓度升高使根和叶的生物量显著增加，土壤干旱使根和叶的生物量显著减小；C，N含量随土壤湿度的增加而显著增加，且在高CO2浓度下的C，N含量高于环境CO2浓度下的含量；从C，N的分配看，在叶中的含量显著高于在根中的含量。大气中CO2浓度升高对C，N积累量的增加减轻了大气的温室效应，且这种作用随着土壤湿度的增加而加大。在高CO2浓度下，贝加尔针茅根和叶的C／N比随土壤湿度的增加而减小，但在当前环境CO2浓度下并未表现出这种变化趋势；贝加尔针茅叶的C／N比远小于根的C／N比，叶的营养价值更高。

Impacts of CO2 Enrichment and Soil Drought on C, N Accumulation and Distribution in Stipa Baicalensis

Stipa baicalensis is one of the main plant communities in grassland in Inner Mongolia and lawn ecosystem in Songnen plain in Northeastern China. The impacts of environmental condition change on C, N accumulation and distribution in Stipa baicalensis were studied. The simulation study shows that the CO_2 concentration in atmosphere enrichment increases root and leaf biomass, and soil drought decreases the root and leaf biomass. The C, N content was markedly increased along with the soil moisture increment, and the C, N content in CO_2 concentration enrichment is higher than that in ambient CO_2 concentration. It can be seen from the C, N distribution that the C, N content in leaf is higher than that in root. The increment of C, N accumulation because of CO_2 concentration in atmosphere enrichment decreases atmospheric greenhouse effect, and this effect would be increased along with the soil moisture sufficient. Under CO_2 concentration enrichment, the C/N ratio in Stipa baicalensis leaf decreases along with soil moisture increment. But, this tendency is not shown under ambient CO_2 concentration. The C/N ratio in Stipa baicalensis leaf is far smaller than that in root. It shows that the leaf nutrition value is higher.