Spatial Distribution Of Soil Organic Carbon And Nitrogen And Phosphorus In The Forestland Of The Yaoxiang Small Watershed In Shandong Province

The spatial heterogeneity of soil organic carbon levels is important in researches of both global carbon-nitrogen cycle and climate change. By employing geostatistics methods and GIS technology, we studied the spatially heterogeneous distribution of SOC and discussed correlation of forest SOC and soil total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen and available phosphorus in the Yaoxiang small watershed in the hilly area of central and southern Shandong Province, which provided a scientific basis for the study of spatial variability of soil nutrient, at the same time, had important guiding significance for evaluating quantitatively ecological service function of forest ecosystems on the small watershed scale.The main results were:(1)The soil bulk density difference of same soil layer was not significant for 5 kinds forestland of Yaoxiang small watershed. The content of soil organic carbon, total nitrogen,total phosphorus, alkali-hydrolyzable nitrogen and available phosphorus in the 10-20 cm soil layer was higher than that in the 0-10 cm soil layer. They are all medium variation.(2)Soil organic carbon in 0-10 cm soil layer had a extremely significant positive correlation with total nitrogen, total phosphorus and alkali-hydrolyzable nitrogen, had a significant negative correlation with soil bulk density, had a not significant correlation with available phosphorus. Soil organic carbon in 10-20 cm soil layer had a significant positive correlation with total nitrogen and total phosphorus, and had a not significant correlation with soil bulk density, alkali-hydrolyzable nitrogen and available phosphorus. Soil organic carbon in 0-20 cm soil layer had a extremely significant positive correlation with total nitrogen and total phosphorus, had a significant positive correlation with alkali-hydrolyzable nitrogen, had a significant negative correlation with soil bulk density, and had a not significant correlation with available phosphorus. Correlation analysis showed, soil organic carbon had a close relationship with total nitrogen, total phosphorus and alkali-hydrolyzable nitrogen, and had a not close relationship with available phosphorus and soil bulk density in the forestland of Yaoxiang small watershed.(3)The spatial distribution characteristics of soil organic carbon and nitrogen andphosphorus in the forestland of Yaoxiang small watershed :①Soil organic carbon content showed high intensity spatial autocorrelation in 0-10 cm,10-20 cm and 0-20 cm soil layer of Yaoxiang small watershed. There were large amounts of organic carbon in the eastern part and northwestern part of Yaoxiang small watershed, organic carbon content in 0-10 cm and 0-20 cm soil layer were closely related. From thef view of the full range, the fractal dimension of soil organic carbon content in 0-10 cm soil layer was the minimum and the coefficient of determination was the maximum, which indicated that the spatial difference of organic carbon content was large and advantages pattern.②Total nitrogen content showed moderate spatial autocorrelation in 10-20 cm soil layer.Total nitrogen content showed high intensity spatial autocorrelation in 0-10 cm and 0-20 cm soil layer of Yaoxiang small watershed. There were large amounts of total nitrogen in the central part and northwestern part of Yaoxiang small watershed, total nitrogen content in 0-10 cm and 10-20 cm soil layer were closely related. From the view of the full range, the fractal dimension of total nitrogen content in 0-20 cm soil layer was the maximum, which indicated that the spatial difference of total nitrogen content was small and the degree of homogeneity was better.③Total phosphorus content showed moderate spatial autocorrelation in 0-10 cm soil layer. Total phosphorus content showed high intensity spatial autocorrelation in 10-20 cm and0-20 cm soil layer of Yaoxiang small watershed. There were large amounts of total phosphorus in the northwestern part of Yaoxiang small watershed. From the view of the full range, the fractal dimension of total phosphorus content in 10-20 cm soil layer was the maximum, which indicated that the spatial difference was small and the degree of homogeneity was better.④Alkali-hydrolyzable nitrogen content showed moderate spatial autocorrelation in 0-10 cm soil layer. Alkali-hydrolyzable nitrogen content showed high intensity spatial autocorrelation in 10-20 cm and 0-20 cm soil layer of Yaoxiang small watershed. There were large amounts of alkali-hydrolyzable nitrogen in the central part of Yaoxiang small watershed.From the view of the full range, the fractal dimension of alkali-hydrolyzable nitrogen content in 0-10 cm soil layer was the minimum and the coefficient of determination was the maximum, which indicated that the spatial difference of alkali-hydrolyzable nitrogen content was large and advantages pattern.⑤Available phosphorus content showed moderate spatial autocorrelation in10-20 cm soil layer. Available phosphorus content showed high intensity spatial autocorrelation in0-10 cm and 0-20 cm soil layer of Yaoxiang small watershed. There were large amounts ofalkali-hydrolyzable nitrogen in the northern part of Yaoxiang small watershed. From the view of the full range, the fractal dimension of available phosphorus content in 10-20 cm soil layer was the minimum and the coefficient of determination was the maximum, which indicated that the spatial difference of alkali-hydrolyzable nitrogen content was large and advantages pattern.