The Relationships Between Litters Of Different Forest Types And Carbon And Nitrogen Mineralization In Soil

Carbon and nitrogen are important components of biological organisms,as well as essential abiotic elements.Carbon and nitrogen cycling are the main processes of material cycling in forest ecosystem.Litter is a primary way to return nutrients in the ecosystem.Litter decomposition determines the thickness of the litter layer,therefore,affects the soil fertility of the woodland.This process is of great significance in improving forest productivity.In this study,surface soils were sampled from forests of Pinus tabulaeformis,Quercus alieua var.acuteserrata and the mixed forest of oak-pine in the Qinling Mountains.We studied the changes of soil ecological stoichiometry characteristics,the organic carbon mineralization,and the nitrate ammonium nitrogen contents in soil under different litter treatments through laboratory cultivation.The aim of this study was to reveal the law of soil organic carbon and total nitrogen mineralization under different litter decomposition.The main findings are as follows:(1)The contents of organic carbon and total nitrogen varied after adding different litters:the contents of total nitrogen and organic carbon increased significantly(p< 0.05)after adding litter of P.tabulaeformis and pine-oak mixed forest.(2)The soil organic carbon mineralization rate under different treatments decreased with time,and soil carbon mineralization rate increased significantly(p< 0.05)after litter addition compared with the control.The differences of soil carbon mineralization rate among three species of litter were not significant(p> 0.05).(3)The nitrogen mineralization rate of soil increased after litter addition.but the soil nitrogen mineralization rates were different among treatments,The addition of litter from P.tabulaeformis significantly improved the rates of nitrogen mineralization in the second and third months(p< 0.05)compared with the control.The rate of nitrogen mineralization increased significantly in mixed forest of pine oak in second month(p< 0.05),while the litter of Quercus alieua var.acuteserrata had no significant effect on the rate of nitrogen mineralization(p> 0.05).The differences in soil nitrogen mineralization rates among three litter adding treatments were significant(p< 0.05).