藏北高寒草甸根系生物量与碳氮分布格局及关联特征

根系生物量的分布格局及其与土壤环境因子的关系对草地保护与退化草地恢复研究有重要意义。以藏北当雄县的高寒草甸为研究对象，在三个海拔上（4300、4500、4700 m）对2011年0-50 cm的群落根系生物量、根碳氮含量、土壤碳含量（SOC、DOC、MBC）、氮含量（DTN、MBN、TN）、碳氮比（MBC/MBN、SOC/TN）、pH、电导率进行了测定，以期探讨藏北高寒草甸根系生物量与碳氮的分布格局及其关联特征。结果表明：（1）土壤中所测量的各种形式的碳氮含量均随着土壤深度的增大呈下降趋势，0-50 cm的DOC和SOC都随海拔的升高呈上升趋势。（2）随土壤深度的增加，根系生物量呈指数下降。随海拔的增加，根系生物量越集中分布于上层土壤，下层土壤根系生物量分布越少且变化趋于平缓。（3）根系生物量与所测的碳氮指标、电导率呈正相关关系，与pH呈负相关关系。根系氮库是影响根系生物量分布格局的主要因素，而pH值、电导率及土壤碳氮指标是影响根系生物量分布格局的重要因素。

Root biomass, carbon and nitrogen distribution pattern and correlation characteristics of alpine meadow in northern Tibet

The distribution of root biomass and its relationship with soil environmental factors are important for the study of grassland conservation and the degraded grassland restoration. This study was based on the alpine meadows in Damxung County, northern Tibet. The root biomass, root carbon and nitrogen content, soil carbon content (SOC, DOC, MBC), nitrogen content (DTN, MBN, TN), carbon to nitrogen ratio (MBC/MBN, SOC/TN), pH, conductivity of 0-50 cm soil depth were measured at three altitudes (4300 m, 4500 m, 4700 m) to explore the distribution pattern of root biomass and carbon and nitrogen in the soil at different altitudes in the alpine meadow, as well as the relationship between them. The results showed that:(1) the various forms of carbon and nitrogen measured in soil presented a downward trend with the increase of soil depth. The total DOC and SOC (0-50 cm depth) showed an increasing trend with the increase of altitude. (2) As the soil depth increased, the root biomass decreased exponentially. With the increase of altitude, the more concentrated the root biomass was in the upper layer of soil, the less the distribution of root biomass in the lower layer, but the change tends to be gentle. (3) The root biomass was positively correlated with the measured carbon and nitrogen indexes and conductivity, while it showed a significant negative correlation with pH. Root nitrogen pool was a main factor affecting the distribution of root biomass in soil. pH, conductivity and soil carbon and nitrogen indicators were important factors affecting the distribution of root biomass in soil.