| In order to clarify the nutrient cycle of Larix principis-rupprechtii plantation under different management measures in Taiyue Mountain,Larix principis-rupprechtii plantations(30a,40a and 50a)and Larix principis-rupprechtii plantations mixed with Betula plalyphylla(15a,26a and 40a)in different ages were studied.Larix principis-rupprechtii plantation in different thinning intensities(0,15%,35%and 50%)were investigated simultaneously to implement the sustainable management of ecosystem service functions.This research measured soil and plant nutrient elements and stoichiometry in each forest land and analyzed the correlations between plant and soil.The main results were as follows(1)Nutrient contents of soil first reduced and then improved with the increase of forest age in Larix principis-rupprechtii plantations and reach the maximum in 50-year-old plantations.The C:P and N:P of soil first increased and then decreased with increase of forest age.The positive correlation between soil ammonium nitrogen content and fine root,leaf nitrogen content was significant.There was a significant positive correlation between the nitrogen contents of fine root and soil total nitrogen content,also the nitrogen contents of needle-leaf.The N:P value of each organ was significantly lower than 14,which verified that Larix principis-rupprechtii plantations in study area were mainly restricted by nitrogen(2)Except for the contents of ammonium and nitrate in the mixed forest of Larix principis-rupprechtii and Betula platyphylla,the other soil nutrient contents decreased significantly with the increase of forest age.The soil C:N improved with the increase of forest age,while the soil C:P and N:P reduced first and then improved with the increase of forest age.The carbon contents,C:N and C:P of fine roots,stems and leaves of Larix principis-rupprechtii were higher than which of Betula platyphylla,while the nitrogen content of fine root and stem and the phosphorus content of stem of Larix principis-rupprechtii were opposite.The leaves N:P of Larix principis-rupprechtii in the 40-year-old mixed forest was 14.510,and the soil available phosphorus content was positively correlated with the fine roots,stems and leaves phosphorus contents of Larix principis-rupprechtii,indicated that the 40-year-old mixed forest was weakened by the nitrogen limit,and more likely to be restricted by phosphorus(3)The soil organic carbon content in the topsoil of Larix principis-rupprechtii plantations with different thinning intensity showed no significant difference with the growing season.The soil organic carbon content increased first and then decreased with the promote of thinning intensity,however the other nutrient contents of soil have no significant change.The average soil N:P of Larix principis-rupprechtii plantation is 4.99 under different thinning intensities,and there were significant positive correlations between the soil total nitrogen content and the nitrogen contents of fine root,stem and leaves of Larix principis-rupprechtii,which verified that the Larix principis-rupprechtii plantations in this study area were mainly restricted by nitrogen. |
