Effects Of Torreya Grandis And Polygonatum Sibiricum Intercropping On Soil Physical And Chemical Properties And Microbial Community

The development of Torreya grandis industry is one of the effective ways to improve the ecological environment in mountainous areas.Pure platalation will often cause soil erosion,increase the cost of afforestation,and the survival rate of trees is not high,which is not conducive to the development of Torreya grandis industry.Planting Polygonatum sibiricum under Torreya grandis forest can not only improve land utilization,but also improve soil nutrients.Based on the research on the soil basic physical and chemical properties,active organic carbon components and soil microbial diversity of Torreya grandis and Polygonatum sibiricum combined management,Torreya grandis pure forest and Polygonatum sibiricum monoculture,the ecological benefits of Torreya grandis and Polygonatum sibiricum intercropping system were analyzed in this experiment.The main results are as follows:(1)In the study of soil physical and chemical properties under different cropping models,the three cropping models had extremely significant effects on soil temperature,SWC,p H,EC,Ca,MBN,?¹⁵N,?¹³C(P<0.01),and had significant effects on Mg,DON,NH₄⁺-N(P<0.05).Different soil layers had extremely significant effects on TN,TP,NO₃^--N,?¹³C(P<0.01),and soil temperature,EC,MBN,NH₄⁺-N(P<0.05).Different cropping models and soil layers had no significant effects on soil bulk density and K,and the interaction between planting models and soil layers had no significant differences on soil physical and chemical properties(P>0.05).With the deepening of soil layer,soil temperature and?¹³C increase,and the contents of EC,TP,MBN,NO₃^--N decrease,showing surface polymerization.(2)In the study of soil organic carbon and its active carbon components under different cropping models,the three models had extremely significant effects on DOC and MBC(P<0.01),and had significant effects on SOC and EOC(P<0.05).The SOC and EOC in different soil layers were significantly different(P<0.01),and the content decreased with the deepening of soil layer.There were no significant differences in DOC and MBC in different soil layers,and the interaction of planting models and soil layers had no significant effects on soil organic carbon and its active carbon components(P>0.05).There was a good linear correlation between SOC and EOC,DOC and MBC,and a very significant positive correlation between EOC and DOC and MBC(P<0.01),there was a significant positive correlation between MBC and DOC(P<0.05).(3)In the study of soil bacterial Alpha diversity index under different cropping models, there was no significant difference in Simpson index among the three cropping models(P<0.05),the Chao1,Observed species and Shannon index were significantly different with different models(P<0.01),PT and P model were significantly higher than T model.In Beta diversity,PCo A analysis showed that there was a great difference between T model,PT and P model.In the analysis of bacterial community structure in different cropping models,at the phylum level,Acidobacteria,Proteobacteria,Chloroflexi and Actinobacteria are the dominant phylum,and the abundance of them reaches more than 75%in the three cropping models,with significant differences(P<0.05).The relative abundance of Acidobacteria and Chloroflexia in PT model was significantly higher than that in P and T model,the relative abundance of Proteobacteria in PT model was significantly lower than that in P and T model,and the relative abundance of Actinobacteria in PT model was significantly lower than that in P model.In the genus level,Subgroup?2?Unclassified,Acidobacteriales?Unclassified,AD3?Unclassified,Elsterales?Unclassified relative abundance are high.Subgroup?2?unclassified,Acidobacteriales?unclassified and AD3?unclassified were significantly different among the three models(P<0.05),and the relative abundance of PT model was significantly higher than that of P and T model.Elsterales?unclassified did not differ significantly in the three models(P>0.05).To sum up,different cropping models of Torreya grandis and Polygonatum sibiricum have certain differences in soil basic physical and chemical properties,soil active organic carbon and its active carbon components,and microbial community structure.The results of this study showed that Torreya grandis and Polygonatum sibiricum intercropping could improve soil nutrients and provide a theoretical basis for improving ecological benefits.