Soil Nutrients Status Of Three Different Forest Types On Karst Area

Soil nutrients status was one of important factor to reflect the conditions of plant growth and development,thus the appropriate edaphic condition is the vitol prerequisites for well establishment and great production of trees.However,in recent years,the pursuit of economic interests and unscientific management have resultsed a significant reduce of the forest quality and eco-function,Therefore,the analysis of different types of soil types of nutrient status has a vital practical significance,and provide a scientific basis for the forest management and sustainable development.In this paper,I analyzed the soils status of three different forest types in Karst area,Guizhou,China:masson pine(MP,Pinus massoniana)plantation,MP natural forest,and slash pine(SP,Pinus elliottii)plantation.The soil physical and nutrient characteristics were analyzed by field investigation and indoor experiment.The results show that:(1)There were significant differences in soil bulk density between different layers of natural MP forest and MP plantation.Soil moisture ranged from 16.27%to 25.54%of all forest type.Organic matter content was the highest across all the surface soil,significantly different to the deepest soil.The total N and total K of MP plantation,and total Kand total P of natural MP forest had significant difference among the soil layers.When comparing the N?P?Ca and Mg contents of three forest types,the Mg content were the highest,in which the average Mg of SP plantation was 0.83 g/kg,0.60 g/kg in MP plantation wheras 0.82 g/kg in natural MP fores,respectively.Total P was the lowest,only 0.03 to o.o4 g/kg among all the forests.There was no significant difference among the content of available elements in the soil layer of each forest type,and the content of ammonium was higher than other available nutrients.The rank orders of trace elements in different soil layers of SP plantation and natural MP forest were significantly various.Distribution patterns of trace elements in MP plantation/natural forest were similar,except the deepest layer in MP plantation.Across all the contents of trace elements in three forest types,Fe had the highest conenet wheras Cr was the lowest.(2)Comparing the same soil layer across different forest types,the contents of Pb,Mn,and Mn in the soil of MP natural forest were the highest among the three forest types,while the content of organic matter was significantly lower than those of other two stands.Mg,Fe,Cu,Zn,Ni,and Mn contents were significantly different,and there was no significant difference between the contents of available elements in the three forest types.The soil pH value were 4.3?4.6.of three forest types,which were negatively correlated with other nutrients.(3)Among the three stands,soil total N and N ammonium showed a negative correlation,whereas the correlation between the trace elements were substantially showed a significant positive correlation(p<0.05)or highly significant positive correlation(p<0.01).The correlations among soil nutrients across forest stands were different,which indicates a various mutual restraint effects on different forest types(4)The total storage of soil nutrients across all the soil layers were MP natural forest>SP plantation>MP plantation,indicating that the utilization efficiency of MP plantation was higher than that of other two forest types.The nutrient acculmulation patterns of three forest types were different along the increase of soil depth.(5)In summary,the nutrient content,nutrient distribution,and nutrient accumulation of three forest types showed obviously different patterns.Therefore,different management trajactories should be applied for these forest types,and to improve their ecological value and economic benefits.