Study On The Difference Between Phenology And Leaf Characters Of Native Quercus Species In Northern China

The protection and utilization of native tree species is the key to the development of modern forestry.Quercus species is the hotspot in the native tree species research field.Quercus is the most diverse and widely distributed genus in Fagaceae,especially in the northern part of China,it is a very important tree species in the broadleaf forest community.This study focuses on the differences of growth and distribution,phenological observation,and leaf characters(leaf morphology and leaf nitrogen content are taken as examples in this study)of native quercetic tree species.Software analysis methods such as Arcgis,Morpho J and SPSS are used to draw the following conclusions:(1)In the study on the growth and distribution of native quercus species,The results show that the native oak species in Beijing are commonly Quercus mongolica Fischer ex Ledebour and Quercus aliena Blume,Quercus dentata Thunberg and Quercus variabilis Blume,which are mainly distributed in suburban mountainous areas.They are more nainly in the mixed forest of pine and oak,with extensive management and even severe damage.In addition,this study investigated the urban landscape in Beijing.The results showed that native Quercus species are very scarce in the urban landscape in Beijing.Taking Jiaokou County in Shanxi Province as an example,Quercus species resources are abundant in Jiaokou County.In order to develop forestry poverty alleviation and establish quercus tree species protection garden,The specific investigation site was located in Naonaoyu,Jiaokou County.that the forest is divided into mixed forests of different ages.And Q.mongolica is the dominant trees species,which is consistent with the findings of the local forestry department.(2)In the study of phenological observation,The main observation site was located in the experimental forest field of Beijing Forestry University,and the main trees were Q.aliena,Q.dentata,and Q.variabilis.From March to November every year,the observation is generally weekly or every two weeks,and the observation frequency of leaf-spreading stage and flowering stage is more frequent.Through observation of phenology,we obtained the bud stage,leaf-developing stage,flowering stage and fruit ripening stage of Q.aliena,Q.dentata,and Q.variabilis in this area.The budding,leaf-spreading,and flowering stages of the three species of Quercus are generally from March to April,and the fruiting stage is generally from late April to September.In addition,each phenological stage of the three species of Quercus had some overlap phenomenon,especially the flowering stage of the three species of Quercus had common overlap phenomenon,which provided the possibility for the hybridization of the three species of Quercus.(3)In the study of leaf morphological difference,The application of this study:(1)Generalized Procrustes Analysis(GPA)superimposed all individuals of the two species,showing the average shape of the leaves of the two tree species in the form of a scatter plot,and dividing the leaf shape for size and shape.(2)Principal Component Analysis(PCA)performs dimensionality reduction on the leaf shape,and uses the first two PC axis to study the leaf shape variation of the two species.The results showed that there are significant differences in the leaf morphology of the two tree species.(3)Allosteric growth analysis(Two Blocks Partial Least Squares,2B-PLS)is used to analyze the co-variation relationship between the shape and size of the leaves,allometric growth.The study found that the leaves of these two species have an allometric growth pattern,as the leaves grow larger,the leaf morphology of these two species has obvious changes.(4)Discriminant Analysis(DA),the discriminant function is used to classify the samples by leaf morphology.The results showed that Q.aliena and Q.dentate can be completely distinguished by their leaf morphological characteristics,and the discrimination rate is 100%.(4)Differences in nitrogen content in leaves,the results showed that the nitrogen content in Q.aliena leaves at different altitudes and different altitudes was There are differences.Using SPSS software to analyze the correlation between the nitrogen content of Q.aliena leaves and geographical factors,it was concluded that the nitrogen content of Q.aliena leaves was not significantly related to the longitude and latitude of these sampling sites,but it was related to the altitude.Geographical factors showed a significant negative correlation.The higher the altitude of the sampling sites in these surveys,the lower the nitrogen content of Q.aliena leaves.