Effects Of Gap Age And Area Of Pinus Massoniana On Plant Diversity,Physical And Chemical Properties Of Soil And Stoichiometric Characteristics Of Camphor

China plantation area in the world,and masson pine(Pinus massoniana)plantation is one of the artificial forest tree species with larger area,P.massoniana adaptation ability strong,resistant to drought or poor,has been the Yangtze river upstream of low hilly land community succession pioneer tree,but because of management mode for the pure forest,cause the loss of forest productivity,soil fertility decline phenomenon such as biodiversity decrease according to current situation of the Yangtze river upstream pure stand of P.massoniana this,carry out mixed transformation experimental study Test conducted in October 2011,the choice of yibin county 39 a high maturity of P.massoniana plantation,by artificial cut down forest gap patches of 7 kinds of size,compared to artificial pure forest of P.massoniana,with 2012,2013,2015 test data as the foundation,in 2018 once again within the forest gap on plant species composition and diversity of soil physical and chemical properties were investigated,and analysis of the characteristics of chemical measurement leaves of Cinnamomum camphora,in order to carry out artificial near natural transformation,large area of P.massoniana plantation of sustainable management to provide certain scientific basis and technical support for the experiment the following results are obtained(1)There are 75 species in 71 genera,55 families in total,including 39 species in36 genera,27 families in shrub layer and 36 species in 35 genera,28 families in herbaceous layer.There are more species under the window than under the forest.The important values of species in the shrub layer are higher than those in the herb layer,such as awn,Osmunda,Festuca arundinacea,Setaria corrugata,etc.which run through all ages of the artificial forest window,indicating that these species have strong adaptability to the environment under the Masson pine forest window.(2)There were significant differences in evenness index and species richness index between gaps(P<0.05).There were significant differences between gap age and species richness index,ecological dominance index and species diversity index(P<0.01),and between gap age and evenness index(P<0.05).The interaction between forest gap age and forest gap area has a significant effect on the richness index(P<0.01).In this study,the index of plant diversity is 1a<2a<7a,increasing year by year,and the plant diversity in 625-900m~2 forest window is high.(3)The interaction of gap age,gap area,gap age and gap area had significant effect on soil organic matter and total nitrogen(P<0.01).The results showed that the soil organic carbon,total nitrogen and total phosphorus all showed 2a<4a<7a,and reached the highest level in 7a,which indicated that the soil fertility had been improved with the passage of the age of the forest window,and the content of soil organic carbon in 625-900m~2 forest window was high,so it was suggested that it could be used as the suitable window area for the transformation of P.massoniana plantation.(4)The interaction of gap age,gap area,gap age and gap area had a significant effect on the contents of C,N and P in leaves of Cinnamomum camphora(P<0.01).In this study,the C content in the leaves of 4a Cinnamomum camphora has the maximum value in G4,and that in the leaves of 7a Cinnamomum camphora has the maximum value in G6.The results showed that when the area of forest window was1225 m~2,the nutrient utilization efficiency of camphor leaves was better.(5)The interaction of gap age,gap area,gap age and gap area had significant effect on C:N,C:P and N:P(P<0.01).The C:N and C:P of 4a leaves were 36.71 and485.20,while the C:N and C:P of 7a leaves were 27.60 and 479.04,indicating that the growth rate of 7a was higher than that of 4a.The ratio of N:P in the leaves of 4 years was 13.21,and the plants were limited by N;the ratio of N:P in the leaves of 7 years was 17.60,which indicated that with the increase of the age of the forest window,the limitation of N in the leaves of camphor was relieved,but the limitation of P was intensified.In conclusion,when the gap age reaches 7 years,the middle-sized gap(625-900m~2)has the highest vegetation richness,the physical and chemical properties of the soil are improved,the soil fertility is better,and the near natural transformation effect of P.massoniana plantation is better.However,when the leaf age of camphor is7 years,the utilization efficiency of nutrients is higher when the area of the gap is1225m~2,and the gap plants are limited by P.