| With the continuous international maritime disputes and the further advancement of China's goal of maritime power,China's Marine industry and the development of uninhabited islands is developing rapidly.Therefore,the study on the protection of uninhabited islands is of no delay.To study the spatial variability of nutrients and the influencing factors,Zhejiang province's uninhabited islands was selected for a case.Based on field investigation of vegetation,soil sampling analysis technology,combined with laboratory analysis,we measured soil p H,organic matter content,total nitrogen,total phosphorus and total potassium.The spatial distribution characteristics of soil nutrients were studied using classical statistics and geostatistics.This study might provide a baseline for the management of soil nutrients in uninhabited islands,at the same time,which may be useful in developing uninhabited islands.The results were showed as follows:1.The characteristics of soil nutrients and related indexes:(1)Analysis of surface soil nutrients and related indexes: the soil was acidic,with a relatively low content of organic matter content,a relatively high content of total phosphorus and total nitrogen,and a medium content of total potassium.The p H value of uninhabited islands in Zhejiang Province ranged from 4.090 to 5.540,with an average value of 4.926.The organic matter content ranged from 3.200 to 14.100 g/kg,with an average of 6.387 g/kg.The total nitrogen ranged from 0.860 to 2.310 g/kg,with an average of 1.433 g/kg.The total phosphorus ranged from 0.400 to 3.162 g/kg,with an average of 1.204 g/kg.The total potassium ranged from 6.090 to 25.300 g/kg,with an average of 14.965 g/kg.(2)The characteristics of soil nutrients and related indexes in the profile: the organic matter content of soil profile was low,the total nitrogen was higher than average,the total phosphorus was high level,the total potassium was medium level,and the cation replacement amount was medium level.On the soil profile,the p H was significantly different.The p H value of A island was ranging from 5.89 to 6.64,while the surface soil with a p H ranged of 4.09 to 5.51.On the soil profile,the p H value of the C island ranged from 5.89 to 6.64,while the p H value of the surface soil ranged from 4.70 to 5.14.The main reason was that soil p H value is mainly related to the base composition of the soil salinity,high base composition of soil salinity has higher soli p H than lower soil salinity.The soil salinity of soil profile has the protection of the surface soil,so it is not easy to get wet.Therefor,the profile of soil has more soil salinity than the surface soli.2.Descriptive statistical analysis of soil nutrients and related indexes: most of the variation coefficients of soil nutrients in uninhabited islands ranged from 10% to90%,showing a moderate degree of spatial variation.The coefficient of kurtosis was >0,Therefore the data distribution is sharp peak.The coefficient of skewness of p H,organic matter content,total nitrogen and total phosphorus in A island and C island was >0,indicating that the data were positive skewness and extreme value appeared at the right end of the data.3.Analysis of spatial variation characteristics of soil nutrients and related indexes: the nugget coefficient of soil p H value in A island was between 25%-75%,showing moderate spatial autocorrelation.The nugget coefficient of soil organic matter content was less than 25%,showing a strong spatial autocorrelation.And the nugget coefficient of p H was between 25% and 75%,showing a moderate spatial autocorrelation.The p H value and total potassium nugget coefficient of C island was between 25%-75%,showing moderate spatial autocorrelation.4.Analysis of influencing factors of soil nutrient related indexes:(1)Correlation analysis of vegetation diversity index and soil nutrient related indexes: In A island,species evenness was positively correlated with p H value.In C island,species richness and soil p H were significantly negatively correlated,species diversity and soil p H were significantly negatively correlated,and species evenness was significantly negatively correlated with soil p H.There were significant differences in the correlation between community diversity index and soil nutrients in C island.There was a significant positive correlation between species richness and total nitrogen.Species diversity was significantly positively correlated with organic matter content.And species evenness was significantly positively correlated with p H value(2)The vegetation characteristics and soil nutrient and related index correlation analysis: species richness,diversity index and soil p H value and had no significant correlation with organic matter content and total potassium.But they had significantly positively correlation with total nitrogen.Among them,the species richness and total nitrogen were extremely significant positive correlation,the species diversity index and soil total nitrogen was significantly positive correlation.(3)The influence of topographic factors and soil nutrient related indexes: among soil nutrient factors,p H value and total phosphorus showed a significant positive correlation,and the line segment length of organic matter in soil nutrient factors was the longest,so organic matter showed a higher explanatory amount to the soil.Among all topographic factors,slope has the longest line segment length,so slope has the highest amount of interpretation for vegetation data and the most obvious influence on soil changes.The p H value,total phosphorus,total nitrogen showed obvious positive correlation,and showed negative correlation with altitude and slope direction.In conclusion,there is an obvious relationship between topographic factors and soil nutrient factors.The uninhabited islands in Zhejiang Province are far away from land and are less affected by human life.Therefore,natural factors such as altitude,climate,vegetation and so on play a decisive role in the development of their ecological environment. |
PDF Full Text Request