Studies On Ecological Stoichiometry Of Phoebe Plantation In Different Ages

Ecological stoichiometric ratio of C?N and P in ecological system can reveal how different elements work together in the growth process of plants,which makes ecological stoichiometry the research focus of global system change.Phoebe bournei is a rare and endangered species(the national second emergency)and it is disappearing.We as researchers focus on how to manage Phoebe bournei in a productive way.We study the ecological stoichiometry of Phoebe bournei plantation in different ages in a bid to know what limits the growth of Phoebe bournei among the nutritious elements and how soil,leaves and roots work together,which will help protect and cultivate Phoebe bournei plantation theorically.We selected three plantations in different stages,namely,Xia Taoyuan(14a),Shu Muyuan(45a)and Shang Siyuan(60a),and we set two plots(25m*25m)in Jindong District for management of Phoebe bournei plantation in Yongzhou City.Respectively,we sampled in January,April,July and October,2016.The main results are as follows:(1)The content of C and N in the soil is 14a>60a>45a and 14a and 60a is much higher than 45a.The content of P is 45a>60a>14a and there is no significant difference among them.C:N decreases,C:P and N:P go up first and then go down as the plantations get older.The content of C and the value of C:P and the content of N and the value of N:P in the plantation of three different ages is extremely correlated(p<0.01).(2)The content of C and P in the leaves is 14a>45a>60a and The content of N is 45a>14a>60a.The content of C and P in the leaves goes down first and then goes up.C:P and N:P go up first and then go down.There is a negative correlation between N and C:N in leaves of 14a(p<0.05).There is a significantly negative correlation between N and C:N in leaves of 45a and 60a(p<0.05).There is a significantly negative correlation between P and C:P in leaves of 14a and 60a(p<0.05).(3)The content of C in the roots is 60a>45a>14a as the age grows and there is a significant difference among them(p<0.05).The content of N and P in the roots is 14a>45a>60a and there is no significant difference among them.The value of C:N,C:P and N:P in the roots goes up as the age grows.There is a mildly negative correlation between N and C:N and between P and C:P in the roots of 14a.There is an extremely negative correlation between N and C:N in the roots of 45a and 60a(p<0.01).There is a significantly negative correlation between P and C:P in the roots of 45a and 60a(p<0.05).(4)There is a significantly negative correlation between the content of C and P in the soil of 14a and between the content of N in the leaves and N in the soil of 45a(p<0.05).There is an extremely positive correlation between the content of C in the roots and the content of P in the soil of 14a(p<0.01).There is an extremely negative correlation between the content of P in the roots and the content of C in the soil of 45a(p<0.01).There is a close relationship between all N indexes in the leaves and the N content in the roots of 14a.There is a close relationship between all N indexes in the leaves and the P content in the roots of 45a.There is a close relationship between all N indexes in the leaves and the C and N content in the roots of 60a.The results of this study shows that the growth of 14a Phoebe bournei is limited by N,the growth of 45a Phoebe is limited by P,the growth of 60a Phoebe bournei is limited by the N and P in Jingdong forestry station.On the whole,the mean of N:P in the leaves of Phoebe bournei is 14.39,which indicates that the Phoebe bournei plantations are limited by both N and P in the area.This study can provide guidance for the better cultivation and management of Phoebe bournei plantations,provide scientific basis for the rational use of land,and provide data support for the construction of national reserve forest strategically.