Study On The Relationship Between Soil Ecological Stoichiometry Of Spruce Plantation In Different Forest Age And Soil Factor

The research set the soil of spruce plantation which in different age(20a,25 a,30a,35 a,40a,45a)in the upstream of Bailong River as the object,which combined the sampling methods in field and laboratory analysis methods to measure the feature of physical and chemical properties of soil on their organic carbon,total nitrogen,total phosphorous,total potassium and available nitrogen,phosphorus,potassium contents,soil p H,soil electrical conductivity,soil water content and soil bulk density in different soil depths during the growth period and analyzing stoichiometric characteristics about soil nutrients.The paper aimed to explore the effects of forest age on the stoichiometric ratio of soil nutrient in spruce plantation forest and the correlativity between physical and chemical properties of the soil,which expected to build up an model between soil physicochemical properties and soil nutrient stoichiometric in improving the ability of soil nutrient and productivity of artificial spruce forests by adjusting the soil physical and chemical properties and the water conservation ability of artificial spruce forest.The conclusions are as follows:(1)The soil nutrient content with the forest age and soil depth shows significant effects.With the increasing of soil depth,the content of organic C,total N,total P,available N,available P,available K and conductivity of the soil decreased gradually,content of the p H and water in soil showed an increasing trend,total K and bulk density had no obvious change law.With aging of forest,the content of organic C and available N of soil showed a "W" trend,meanwhile,total N,total P,available P and available K content showed an "N" trend of the soil.Soil p H and conductivity showed a trend of rise first then fall,as soil water content and soil bulk density did not change obviously.Soil nutrients before 30 years were lower than those after 30 years.(2)Forest age and soil depth shows an significant effect on soil C:N,C:P,C:K,N:P,available N:P,available N:P and available P:K with the.Besides the C:P,others were not stable with the increasing age of forest,as it showed a high coefficient of variation.The ratio of soil(except N:P and available N:P)decreased with the increase of soil depth.From the soil C:N,C:P,C:K,N:P and available N:P values,it is necessary to add more N in the soil of the study area.The content of P is sufficient and the K content is scarce.The artificial forest was controlled by soil P before 30 years and by soil N after 30 years.(3)Organic C and P were the key factors of C:N,C:P,C:K,N:P,available N:P,available N:K and available P:K.The correlation analysis showed that there was a significant positive correlation among the soil organic C,total N and total P(P<0.01),a significant positive correlation among available N and soil organic N,total N,total P and a significant positive correlation between organic matter C and total P.There was no correlation between available K and other soil nutrients.There was a significant positive correlation between soil C:N and available P.The correlation between C:P and available P(significant negative correlation)was greater than total P,total K and C:N.Correlation between C:K and soil organic C(very significant positive correlation)was greater than total N,P,available N and available P.The correlation between N:P and soil available P was significantly higher than total P.Correlation between available C:N and C:P was more significant than that of total K,available P,C:N and C:P.Correlation is higher between available N:K and C:K.The correlation is mostly close between available P:K and available P(most significant positive correlation).(4)Soil conductivity had the greatest influence on soil C:N,C:P,C:K,N P.There was a significant positive correlation among soil C:N and soil p H,conductivity(P<0.01)and positively correlated with soil water content and bulk density(P<0.05).Whose influence degree for C:N: the soil electrical conductivity > soil p H > soil bulk density > soil water content.Soil C:P and soil p H,conductivity and water content were significantly negative correlation,which was no significant correlation with the soil bulk density(P>0.05).The influence degree for C:P: soil p H > soil conductivity > soil water content > soil bulk density.Soil C:K were extremely significant positive correlation to the soil electrical conductivity and the soil bulk density who had no significant correlation with soil p H and water content were on the contrary.There were significantly negative correlation among soil N:P and soil p H,conductivity,water content,there was no significant correlation with the soil bulk density.Influence degree for N:P: soil conductivity >soil p H > soil water content>soil bulk density.(5)The effect of soil p H on soil available N: P,available N: K,available P: K was the highest.There were significantly negative correlation(P<0.01)among soil available N:P and soil p H,conductivity,water content,there was no significant correlation with soil density.Influence degree for available N:P: soil p H>soil moisture content>soil conductivity>soil bulk density.There was significantly negative correlation between soil available N:K and soil bulk density(P<0.05),among the soil p H,conductivity and water content had no significant correlation(P> 0.05).There were very significant positive correlation among the soil available P:K,soil p H and its conductivity,which was significantly positively related to soil water content and soil bulk density.Influence degree for available P:K: soil p H>soil conductivity> soil bulk density >soil moisture content.