Study On Spatial Heterogeneity Of Soil Active Iron And Compare With Total Carbon And Total Phosphorus Of Alpine Grassland In Northwest Sichuan

The content and distribution of soil active iron affect the level of plants for the iron,while the bio-toxicity of contaminants in the soil such as heavy metals and the validity of nutrients.Specially,the iron cycle in wet soil has an important significance of environmental indication. The spatial heterogeneity of soil active iron in alpine meadow and alpine marsh of alpine area in the Northwestern Plateau of Sichuan has been analyzed, including three different plot scales,by applying geo-statistical methods.The similarities and differences of the spatial heterogeneity between iron and total carbon and total phosphorus has been analyzed.The results showed that:(1) The variability of soil active iron in alpine meadow and alpine marsh is moderate. The spatial heterogeneity of soil active iron in alpine marsh is found to be higher than in alpine meadow. With plot scales increase,there has no significant difference in the spatial heterogeneity of soil active iron in alpine meadow,but the spatial heterogeneity levels of soil active iron in alpine marsh decreases gradually. (2)Soil active iron in alpine meadow has a strong spatial autocorrelation at the big polt scale,while soil active iron in alpine marsh has a strong spatial autocorrelation at the small polt scale.And the scale of spatial heterogeneity of soil active iron in alpine meadow increases with plot scales increase,but there has no diversification in alpine marsh.(3)The results of anisotropic ratio show that soil active iron has a stronger anisotropic structure in N90°direction in alpine meadow, and has a anisotropic structure in N90°and N135°directions in alpine marsh.(4) 10 m×5m is more appropriate plot scales for expressing the spatial correlation of soil active iron in alpine meadow;and 2 m×1 m and5 m×2.5 m are more appropriate plot scales for soil active iron in alpine marsh. The spatial heterogeneity of active iron in alpine meadow is influenced by species and plant cover,soil elements(total carbon and total phosphorus) and micro-terrain.The distribution and migration of soil elements will cause spatial heterogeneity of soil active iron in alpine meadow. The spatial heterogeneity of active iron in alpine marsh is influenced by species, micro-terrain and soil moisture.(6)In alpine meadow,the variability of soil active iron dose not have significant changes at different plot scales. The variability is moderate.While there are significant changes of the variability of soil total carbon at different plot scales. The spatial autocorrelation of soil total carbon is obvious at the bigger polt scale. Soil total phosphorus is the strongest one in the variability ,but the spatial autocorrelation is weak.The random factors have great proportions.