Effect Of Mixed Phyllostachys Edulis And Wood On Plants Growth And Soil Environment Under Different Light Condition

Phyllostachys edulis is an important component of forest resources in China.The development of P.edulis forest integrates ecological,economic and social benefits and is an important part of forestry production.However,the sustainable management of P.edulis forest is challenged due to the poor environmental conditions of P.edulis forest,the poor growth of P.edulis and the decline of bamboo price.In order to solve this practical problem,P.edulis-wood mixed forest as a good way of management is strongly advocated.The interaction between P.edulis and associated tree species in bamboo-wood mixed forest plays an important role in tree survival and growth as well as the maintenance of stand stability.However,the ecological relationship and interaction between bamboo-wood has not been determined yet.In addition,plant interactions in natural communities are influenced by various abiotic factors.As an important factor driving the productivity of forestland,light conditions regulate the interaction between plants,so enhancing the understanding of the influence of light conditions on bamboo-wood interaction has important theoretical significance,and can provide scientific basis for the further ecological management of P.edulis forest.The interaction between tree species in mixed forest plays an important role in the survival and growth of trees and the maintenance of stand stability.light,as an important factor driving forest productivity,regulates the interaction between plants.In this study,Phyllostachys edulis,Phoebe chekiangensis and Torreya grandis were taken as the research object,and two light intensity and five planting methods were set:(Pc:monocropped P.chekiangensis,Tg:monocropped T.grandis,Pe: monocropped P.edulis,Pc/Pe: P.chekiangensis/P.edulis,Tg/Pe: T.grandis/P.edulis.By measuring plant morphological growth,biomass accumulation and distribution,nutrient physiology,chlorophyll content,root morphological characteristics,soil chemical properties and soil biological characteristics and other indicators,this paper studied the growth and physiological adaptation of three plants to light intensity changes under different planting methods and their influence on soil environment,and explored the influence mechanism of light intensity on plant interaction,In order to provide theoretical support for the transformation of P.edulis pure forest.The main results are as follows:The effects of mixed culture on plant growth and aboveground physiological characteristics were light-dependent and species-specific.Under high light conditions,the plant height and biomass accumulation of P.edulis and P.chekiangensis mixed increased significantly compared with monocultures,and the root-shoot ratio also increased significantly.For specific leaf area,mixed culture could promote P.chekiangensis and T.grandis,but inhibit that of P.edulis.In addition,mixed culture significantly increased the aboveground and root nitrogen concentration of the three plants.Under low light intensity,biomass accumulation,plant height,relative growth rate and aboveground nitrogen concentration of the three species were significantly increased under monoculture mode compared with high light intensity.However,the biomass accumulation,plant height and aboveground nitrogen concentration of T.grandis and P.chekiangensis were significantly reduced by mixing with P.edulis compared with monoculture treatment.Under both light intensities,chlorophyll concentration of both companion trees in mixed mode was significantly inhibited.Plant root morphology and physiological characteristics were affected by planting pattern and light intensity.Total root length,root surface area,N acquisition efficiency per unit root surface area and N acquisition efficiency per unit root length of the three plants under mixed culture increased compared with monoculture treatment,while the specific root length of P.chekiangensis and T.grandis decreased.Compared with monoculture treatment,the root biomass,total root length and root surface area of P.chekiangensis and T.grandis showed a decreasing trend under low light intensity mixed culture.Mixed culture had different inhibitory effects on root physiological characteristics of the three plants.PCA analysis showed that the root morphological and physiological score of P.chekiangensis was significantly reduced by mixed culture under low light intensity.Regression analysis showed that chlorophyll concentration and plant height were positively correlated with aboveground biomass,total biomass and aboveground nitrogen concentration.The results showed that there was a positive correlation between aboveground nitrogen concentration and root morphological and physiological scores of P.edulis and P.chekiangensis.Compared with monoculture,P.chekiangensis and T.grandis mixed with P.edulis significantly affected soil chemical properties and soil enzyme activities.Under both light conditions,soil organic matter and total nitrogen concentration in the two mixed culture were significantly decreased compared with those in the three monoculture modes,and soil urease,protease and acid phosphatase activities were significantly increased compared with those in the three monoculture modes.Under high light intensity,compared with T.grandis and P.edulis monoculture,T.grandis mixed with P.edulis significantly improve soil alkali-hydrolysable nitrogen concentration.In addition,the soil available P and p H of two companion tree species and P.edulis under monoculture,the mixing of P.chekiangensis and T.grandis showed promoting and inhibiting effects,respectively.Under low light intensity,the mixed culture significantly reduced the soil alkali-hydrolyzable N concentration and available P,compared with the monoculture treatment of P.chekiangensis and T.grandis.However,for P.edulis monoculture treatment,mixed culture only had an inhibitory effect on soil alkali-hydrolyzable nitrogen.The differences of bacterial and fungal community structures under different planting patterns and light intensity were analyzed by high-throughput sequencing.In all the treatments,Proteobacteria,Acidobacteriota,Actinobacteriota and Chloroflexi were the dominant bacteria.Ascomycota and Basidiomycota were the dominant phyla of fungi.According to the comparison of bacterial and fungal community diversity(Ace,Chao1,Shannon and Simpson index),the mixed treatment had relatively little effect on the richness index(Ace and Chao1)and diversity index(Shannon and Simpson index)of soil bacterial and fungal community under high light intensity.However,under low light conditions,the richness index and Shannon index of soil bacterial and fungal communities were significantly decreased under mixed treatment compared with P.chekiangensis and T.grandis monoculture.The β diversity of soil bacteria and fungi was analyzed by nonmetric multidimensional scaling(NMDS).It was found that the similarity of bacterial and fungal communities increased with the decrease of light intensity.The results of Pearson correlation analysis showed that the concentration of organic matter,total nitrogen,available N,available P,urease and protease were significantly correlated with most bacteria and fungi(p<0.05)In conclusion,compared with monoculture of the three plants,mixed treatments influenced plant growth and physiology as well as root system traits,but these effects were regulated by light intensity.The three species showed positive interspecific relationship under high light,while the growth of the two companion species was inhibited under low light.In addition,the effects of mixed treatment on soil environment vary with light intensity.Therefore,strengthening the research on the regulation of light environment on the mixed effect can provide a theoretical basis for the transformation of P.edulis pure forest,and has important practical significance for the ecological management of P.edulis forest.