Relationships between soil factors and grassland degradation on an alpine grassland based on redundancy analysis

Based on research sample plots on a degraded alpine grassland, we observed plant community characteristics, collected soil samples, and analyzed soil physical and chemical properties according to the basic principles of quantitative ecology, the relationships between a degraded grassland and soil factors in an alpine grassland were discussed. The first sorting axis of the redundancy analysis ordination diagram showed the distribution of the degree of degradation in the grassland. The grassland plant community was negatively correlated with the first sorting axis, followed by vegetation coverage, aboveground biomass, and underground biomass. The first and second sorting axes explained 97.1% of the relationships between grassland degradation and soil factors. Sand and pH were positively correlated with the first sorting axis. Soil organic carbon, soil water content, bulk density, total nitrogen, and available nitrogen were negatively correlated with the first sorting axis. The relationship between soil factors and grassland degradation varied and was highly significant in all sorting axes (P<0.01). The relationship between soil organic carbon (r=-0.890), soil water content (r=-0.864), bulk density (r=-0.847), total nitrogen (r=-0.836), and available nitrogen (r=-0.821) with alpine meadow degradation were highly significantly correlated (P<0.01). Redundancy analysis of degraded grassland community characteristics and the soil factor data matrix reflected the relationship between soil factors and grassland degradation and the degree of correlation between soil organic carbon, soil water content, bulk density, total nitrogen, and available nitrogen were the main factors affecting grassland degradation of the alpine grassland.