西藏北部不同草地类型土壤碳、氮、磷的变化特征

目的]探讨西藏北部不同草地类型间土壤碳氮磷含量的分布规律和各养分间相互关系,为草地生态保护和评价提供理论依据。方法]通过S形土壤取样法对西藏北部不同草地类型的土壤样品进行采集,利用试验测定土壤的碳氮磷含量,基于SPSS进行方差分析和相关性分析。结果]山脊高寒草甸、高寒灌丛草甸和山腰高寒草甸有机碳含量主要受海拔高度的影响,有机碳含量随着海拔高度的增加而增加,随土层深度加大而降低;有机碳与全氮有极显著正相关关系,相关系数为0.968(p0.01),不同草地类型间全氮含量趋势与有机质趋势相同;除高寒沼泽草甸,其他草地类型的有效氮与全氮分布规律相同,有效氮含量和全氮含量之间存在显著正相关关系,相关系数为0.439(p0.05)。速效磷受全磷含量影响显著,速效磷与全磷的相关系数为0.442,为极显著正相关关系;全磷含量受放牧影响,但放牧对速效养分的影响更加明显。结论]西藏北部不同草地类型土壤碳、氮、磷的具有一定的变化规律,草地退化与放牧强度具有一定联系。

Changes of Carbon, Nitrogen and Phosphorous in Soils Under Different Grassland Types in Northern Tibet

Objective] The distribution of carbon, nitrogen and phosphorous in soils under different grassland types and the relationships between different nutrients in Northern Tibet was explored in order to provide a theoretical basis for grassland protection and evaluation.Methods] Soil samples of different grassland types in Northern Tibet were collected by s-shaped soil sampling method, and the carbon, nitrogen and phosphorus content of the soil was measured by test. Variance analysis and correlation analysis were conducted based on SPSS.Results] The organic carbon in ridge alpine meadow, alpine shrub meadow and hillside alpine meadow was mainly affected by elevation. The organic carbon increased with elevation while decreased with soil depth. The organic carbon was significantly correlated with total nitrogen, and the correlation coefficient was 0.968(p<0.01). The total nitrogen and organic matter had the same trend in different grassland types. Except alpine swamp meadow, the distribution pattern of available nitrogen and total nitrogen were the same that in other grassland types. There was a significantly positive correlated between available nitrogen and total nitrogen, and the correlation coefficient was 0.439 (p<0.05). Rapidly available phosphorus was significantly positive correlated with total phosphorus, and the correlation coefficient was 0.442. The total phosphorus content was affected by grazing, but the effect of grazing on available nutrients was more obvious.Conclusion] The carbon, nitrogen and phosphorous of different grassland in Northern Tibet shows a regular change, grassland degradation has a certain correlation with grazing intensity.