Ecological Stoichiometry Characteristics And Seasonal Variation In Continuous Planted Eucalyptus Plantations

Ecological stoichiometry is to unify the biological characteristics of different research fields,different biota,and at different scales by analyzing the C,N,P chemical elements and stoichiometric laws of the organism and its environment.It has become one of the hotspots in the ecology field.In this study,we chose four kinds of continous planted Eucalyptus plantations in the Dongmen Forest Farm of Fusui,Guangxi as reseach object.And we studied carbon,nitrogen and phosphorus ecological stoichiometry characteristics of leaves,branches,fine roots,litter and soil.And we analyzed the seasonal dynamics,the variation law of continuous planting of carbon and phosphorus contents and ecological stoichiometric ratio.Meanwhile,It was briefly discussed about the relationship between leaves,branches,fine roots,litter and soil of carbon,nitrogen and phosphorus.The main results are as follows:(1)The C content was in order as:leaves or litter leaves>branches>fine roots;N content of the order was leaves>litter leaves>branches>fine roots;P content of the order was leaves>branches>fine roots>litter leaves.(2)It was not obvious that the C content of eucalyptus organs changed with the increas of continuous planting generations.Both of the N and P content reduced first and then increased with the increas of continuous planting generations.The C:N,C:P of eucalyptus organs also increased first and then reduced with the increas of continuous planting generations.The ratio of C:N,C:P could reflect plant’s growth rate,So more planting generations would lower the speed of eucalyptus growth.In this study,it is appropriate to continuously plant 2 to 3 times in order to ensure economic efficiency of eucalyptus plantations.(3)In this study,the leaves’ N:P of different planting generations ucalyptus plantations ranged 10～12.According to Braakhekke’s research,it showd that the growth of eucalyptus was limited by both N and P in the areas.(4)There was no significant difference in soil C content between different planted generations eucalyptus plantations.The N content in the two layers decreased first and then increased with the increase continuous planting generations.The P content increased gradually.There was no significant difference in soil C:N between different planted generations eucalyptus plantations.The ratio of C:P and N:P reduced gradually.(5)The P content and C:P ratio of leaves and branches of different planted generations eucalyptus plantations were limited by N content in 0～20cm soil.The C content of fine roots was limited by soil P content.The P content of litters could affect the soil N content.