基于多变量分析的天祝金强河地区退化高寒草甸土壤因子分类模型

Classificational model of degraded grassland based on multivariable analysis method in the area of Jinqiang River,Tianzhu County

【目的】探索性建立以土壤有机质、全氮、水解氮、速效磷、速效钾和pH值为辅助监测指标的退化高寒草甸的分类模型,以期揭示退化高寒草甸的土壤养分和pH值的变化规律及对其影响程度.【方法】在天祝金强河地区选取了14块样地,利用主成分分析法找出退化高寒草甸的主要影响指标,聚类分析法对样地进行分类,然后用多变量方差分析法验证了此模型的合理性.【结果】有机质和全氮,有机质和水解氮,全氮和水解氮,速效钾和全氮,速效钾和水解氮、速效磷和水解氮,速效钾和速效磷,速效磷和pH值之间具有线性相关性;从这6个指标提取出了2个主成分,第一主成分是土壤养分,即水解氮、全氮和有机质,其贡献率为62.7%,即高寒草甸的退化程度主要体现在水解氮、全氮、有机质上,且它们在主成分上的系数分别为0.4784、0.4748、0.4124;第二主成分是土壤pH值,其贡献率为17.3%.【结论】14块样地的分类结果是未退化、轻度退化、中度退化和重度退化,以土壤因子为辅助监测指标的分类结果与野外实地考察结果基本吻合。随着高寒草甸退化程度地不断加重,水解氮、全氮和有机质含量在相应减少,对退化高寒草甸的影响是显著的(P<0.05),土壤pH值逐渐升高后又略有下降,但pH值(P>0.05)在退化高寒草甸中的影响不显著.

【Objective】A classification model of degraded alpine meadow was established with soil organic matter,total nitrogen,hydrolytic nitrogen,fast-acting phosphorus,fast-acting potassium and pH as auxiliary monitoring indexes,in order to reveal the changing law of soil nutrients and pH and the influence degree on them.【Method】Fourteen sample plots were selected in the area of Jinqiang River,Tianzhu county.Principal component analysis was used to find out the main influence indexes of degraded alpine meadow.Cluster analysis was used to classify the sample plots.Then,the rationality of the classification model was verified by multivariate variance analysis.【Result】There was a linear correlation between organic matter and total nitrogen,organic matter and hydrolytic nitrogen,total nitrogen and hydrolytic nitrogen,fast-acting potassium and total nitrogen,fast-acting potassium and hydrolytic nitrogen,fast-acting potassium and fast-acting phosphorus,fast-acting phosphorus and soil pH.Two principal components were extracted from these six indicators.The first principal component is soil nutrient,that is,hydrolyzed nitrogen,total nitrogen and organic matter,and its rate of contribution is 62.7%.That is to say,the degradation degree of alpine meadow is mainly reflected in hydrolyzed nitrogen,total nitrogen and organic matter,and their coefficients on principal components are 0.4784,0.4748 and 0.4124 respectively;the second principal component is soil pH,with contribution rate of 17.3%.【Conclusion】The classification results of 14 sample plots were non-degraded,lightly degraded,moderately degraded and heavily degraded,and the classification results with soil factors as auxiliary monitoring indicators were basically consistent with the results of field survey.With the deterioration of alpine meadow,the contents of hydrolyzed nitrogen,total nitrogen and organic matter decreased correspondingly,which had significant effect on degraded alpine meadow(P<0.05).soil pH gradually increased and then decreased slightly,but pH(P>0.05)had no significant effect on degraded alpine meadow.