Effects Of Nitrogen Addition On Physiological Growth Characteristics And Interspecific Relationship Of Phyllostachys Edulis And Phoebe Chekiangensis

Phyllostachys edulis is the most important economic and ecological bamboo species in Zhejiang Province.The bamboo industry with Phyllostachys edulis as the main raw material has become the pillar industry of rural economic and social development in the vast bamboo areas of Zhejiang Province and the main source of farmers’ family economic income,but the economic benefits of pure Phyllostachys edulis forest have decreased significantly.The wood processing industry in Zhejiang Province is developed,but the source of precious tree timber mainly depends on import.Combined with the above two problems,it is worth studying how to develop precious tree species on a large scale in the limited suitable forest resources in Zhejiang Province,and how to develop precious tree species on a large scale in combination with the rich Phyllostachys edulis forest resources in Zhejiang Province.In addition,considering the importance of nutrients to plants and the large amount of nutrient consumption brought by fast growth and high yield of Phyllostachys edulis,it is particularly important to pay attention to the utilization and distribution of fertilizer,especially nitrogen.Therefore,this study takes Phyllostachys edulis and Phoebe chekiangensis as the research object,studies the effects of Nitrogen Application on the growth morphological characteristics,physiological characteristics and competition relationship of Phyllostachys edulis and Phoebe chekiangensis seedlings by setting different nitrogen levels and planting methods,analyzes the interspecific intensity of Phyllostachys edulis and Phoebe chekiangensis under nitrogen application conditions,and discusses the effects of Nitrogen Application on the physiological and ecological characteristics and interspecific competition relationship of Phyllostachys edulis and Phoebe chekiangensis,It provides a theoretical basis for the transformation of precious species of Phyllostachys edulis forest.The main results are as follows:(1)Nitrogen addition promoted the growth of Phoebe chekiangensis and Phyllostachys edulis.The ground diameter and total biomass of Phoebe chekiangensis under the mixed forest increased significantly,and the tree height,root diameter and volume,leaf thickness,specific leaf area and dry matter increased to a certain extent.The trend of nitrogen addition under pure forest was similar to that under mixed forest.The total biomass,root diameter and volume,specific leaf area of leaves increased significantly,while the ground diameter,tree height,root surface area,leaf thickness and dry matter increased to a certain extent.The underground biomass of Phyllostachys edulis under pure forest increased to a certain extent.It can be seen that the addition of nitrogen promoted the growth of underground roots,increased leaf thickness and leaf dry matter accumulation,and then promoted the growth of aboveground parts of Phoebe chekiangensis.(2)Nitrogen addition promoted the growth of Phoebe chekiangensis and Phyllostachys edulis,significantly affected the root growth of Phoebe chekiangensis,but had no significant effect on the physiological and ecological adaptability;Phyllostachys edulis and Phoebe chekiangensis showed different physiological adaptability under the two forests.It was concluded that Phoebe chekiangensis had stronger physiological and ecological adaptability under mixed forests,while Phyllostachys edulis had stronger physiological and ecological adaptability under pure forests;Nitrogen addition had no significant effect on the physiological and ecological adaptability,while the stand type had a certain impact on the survival of the two species.Phoebe chekiangensis had a stronger physiological and ecological adaptability under the mixed forest,while Phyllostachys edulis had a stronger physiological and ecological adaptability under the pure forest.Under mixed forest treatment,soluble sugar,two nitrogen metabolizing enzymes GS and NR were significantly higher than those under pure forest treatment;The content of SOD in leaves of Phoebe chekiangensis under pure forest treatment was significantly higher than that under mixed forest treatment;Pure forest treatment was beneficial to increase the content of photosynthetic pigments in Moso bamboo.The total contents of three photosynthetic pigments and photosynthetic pigments were significantly higher than those in mixed forest treatment.The activity of nitrogen metabolizing enzyme GOGAT was significantly higher in pure forest treatment than that in mixed forest treatment;Under mixed forest treatment,the soluble sugar of only osmotic adjustment substance in Phyllostachys edulis was significantly higher than that in pure forest treatment.(3)There is a certain competitive relationship between Phyllostachys edulis and Phoebe chekiangensis.Planting Phoebe chekiangensis under the forest needs to cut down the two diameter classes of Phyllostachys edulis,11 ～ 14 cm and 14 ～ 17 cm,within the 4m competitive range of Phoebe chekiangensis.Phyllostachys edulis has interspecific competition with Phoebe chekiangensis.As a competitive wood,Phyllostachys edulis accounts for 64.29% in the diameter class of 8 ～ 11 cm,and the average competition index in the diameter class of 11 ～ 14 cm and 14 ～ 17 cm is the highest.Therefore,considering the competitive pressure of the growth of Phyllostachys edulis under the forest,when the Phyllostachys edulis increases every year,the number of Phyllostachys edulis in the diameter class of 8 ～ 11 cm can be appropriately reduced,and the Phyllostachys edulis in the diameter class of 11 ～ 14 cm and 14 ～ 17 cm within the 4m competition range of Phyllostachys edulis can be felled to a certain extent to ensure the growth of Phyllostachys edulis.To sum up,nitrogen addition promoted the growth of Phyllostachys edulis and Phoebe chekiangensis,significantly affected the root growth of Phoebe chekiangensis,but had no significant effect on the physiological and ecological adaptability;Phyllostachys edulis and Phoebe chekiangensis showed different physiological adaptability under the two forests.It was concluded that Phoebe chekiangensis had stronger physiological and ecological adaptability under mixed forests,while Phyllostachys edulis had stronger physiological and ecological adaptability under pure forests;In terms of interspecific competition between Phoebe chekiangensis and Phyllostachys edulis under the mixed forest,it was proposed to appropriately reduce the number of Phyllostachys edulis in the diameter class of 8 ～ 11 cm,and give some guidance and suggestions for the Phyllostachys edulis in the diameter class of 11 ～ 14 cm and 14 ～ 17 cm within the 4m competition range of Phoebe chekiangensis.