Study On Stand Growth And Soil Physicochemical Properties Of Different Structures Of Melia Azedarach L Plantation In Plain Agricultural Area

In order to explore the relationship between plantation growth and soil physical and chemical properties of different structures of Melia azedarach L plantations in plain agricultural areas,this paper provides a theoretical reference for tree species selection and structural allocation during plantation in this area.This paper takes five different structures of Xihua plantation Farm in Henan Province.Melia azedarach L plantation was the research object,and the Melia azedarach L and pure plantation was used as the control.Through the method of forest survey and laboratory analysis,the stand factors,soil physical properties,soil carbon and nitrogen content and soil moisture were measured and compared.The results are as follows:(1)The DBH,tree height and volume of the bitter plantation with five different stand structures were improved,the average DBH,tree height and volume of Melia azedarach L pear tree mixed forest were 1.13 cm,0.6m and 0.0185m3 higher than that of Melia azedarach L pure plantation,reached a significant difference with Melia azedarach L plantation pure plantation(P<0.05).In terms of coefficient of variation,except for the DBH and tree height coefficient of variation of Melia azedarach L oil peony mixed forest,the coefficient of variation of other plantation structures was smaller than that of Melia azedarach L plantation.(2)The Melia azedarach L plantations with different structures have an effect on the soil physical properties.Compared with Melia azedarach L and pure plantation,different structures of Melia azedarach L plantation reduced soil bulk density,improved soil pore status,and increased soil water holding capacity,capillary water holding capacity,non-capillary water holding capacity and saturated water holding capacity.(3)Compared with Melia azedarach L plantations,different structures of Melia azedarach L plantation can increase soil organic carbon content and total nitrogen content,and the organic carbon content and total nitrogen content of Melia azedarach L,white,pear,tree oil,peony mixed forest and Melia azedarach L white pear tree mixed forest are significantly higher than that of Melia azedarach L plantation in different Melia azedarach L layers.Pure plantation(P<0.05),and the organic carbon content and total nitrogen content of 0-10 cm and 10-20 cm soil layers were significantly higher than 20-40 cm and 40-60 cm soil layers.(4)From June to August,the moisture content of Melia azedarach L pear tree mixed forest and Melia azedarach L white pear tree mixed forest in different soil layers was higher than that of other structures.From September to December,the moisture content of Melia azedarach L oil peony mixed forest in different soil layers was higher than that of other structures.(5)DBH,tree height and volume were significantly positively correlated(P<0.01),and the correlation with other factors was not significant(P>0.05);soil bulk density and field water holding capacity,organic carbon content,total nitrogen The content was significantly negatively correlated(P<0.01),and negatively correlated with capillary porosity(P<0.05).There was a significant positive correlation between organic carbon and total nitrogen(P<0.01).(6)Using the membership function method to comprehensively evaluate the different structures of the Melia azedarach L plantation,and sort according to the average membership degree: Melia azedarach L white pear tree mixed forest> Melia azedarach L,white,pear,tree oil,peony mixed forest> Melia azedarach L pear tree mixed forest>aged white soy sauce peony mixed forest> Melia azedarach L oil peony mixed forest.