Response Of Plagiomnium Acutum Growth To Different Decay Classes Of Pinus Massoniana Deadwood Substrate

Plagiomnium acutum belongs to the genus Plagiomnium in the family Mniaceae.It has beautiful plant morphology,strong covering ability,and medicinal value,so it has a broad application market and prospect.Numerous studies have demonstrated the significant impact of bryophytes on the decomposition of deadwood,with deadwood in turn affecting the growth of bryophytes.However,the exact mechanism by which forest deadwood influences the growth of mosses remains unclear.Furthermore,there is a critical need to investigate how bryophytes facilitate the decomposition of deadwood,as well as the material circulation mechanisms underpinning their interaction.The object of study will select five decay classes of Pinus massoniana and P.acutum as experimental materials to systematically explore the relationship between the growth status of P.acutum and the physicochemical properties and microbial community characteristics of P.massoniana deadwood substrates by means of greenhouse pot experiment combined with high-throughput sequencing techniques.The results of this study provide guidance and reference for the promotion of bryophyte cultivation in deadwood substrate and provide theoretical support for further study of the interaction mechanism between bryophyte and deadwood.The main conclusions are as follows:(1)In terms of the growth status of the P.acutum: The fuzzy membership function was used to comprehensively evaluate the growth and development status of P.acutum.The results showed that the substrate with higher decay classes(IV and V)was more favorable to the growth of P.acutum.Among them,chlorophyll content,growth length,growth coverage,and nutrient content of class IV P.massoniana deadwood with a grain diameter of 10–20 mm were prominent,which indicated that the overall growth condition was better and the growth and reproduction rate were faster and could be used as the best substrate treatment for cultivation.Correlation analysis showed that increasing the water holding porosity,water holding capacity,total nitrogen,total phosphorus,total potassium and lignin content in the substrate to a certain extent had positive effects on the growth of P.massoniana.Bacillus,Bradyrhizobium,norank＿f＿＿Xanthobacteraceae,norank＿f＿＿norank＿o＿＿IMCC26256,Unclassified＿p＿＿Ascomycota,Mortierella,Trechispora and unclassified＿p＿＿Rozellomycota in deadwood may promote the growth of P.acutum.(2)In terms of the physicochemical properties of substrates,it was found that there were significant differences in the physicochemical properties of the substrates of P.massoniana under different treatments.To a certain extent,reducing the particle diameter of the substrates would help to reduce the bulk density and aeration porosity and increase the water-holding capacity and water-holding porosity.In addition,it was found that the growth of P.acutum can change the physical and chemical properties of the substrate,and it has a significant effect on the chemical properties of the substrate.The correlation analysis between the physical and chemical indexes of deadwood and the microbial community showed that the contents of total nitrogen,carbon-nitrogen ratio,condensed tannin,total phosphorus,total potassium,and cellulose in the substrate were the key factors affecting the changes in bacterial community structure,while the contents of total nitrogen,carbon-nitrogen ratio,condensed tannin,total nitrogen,and p H in the substrate were the key factors affecting the changes in fungal community structure.(3)In terms of the changes in substrate microbial community characteristics,the highest bacterial diversity was found in class I(W1 treatment),and the highest fungal diversity was found in class V(W5 treatment).The bacterial richness of classes IV and V was higher than that of classes I,II,and III,and the fungal richness of grade V was significantly higher than that of other classes(P < 0.05).The microbial community structure of class I deadwood was significantly different from that of other classes(P < 0.05),and most bacterial and fungal groups were significantly enriched in class I deadwood(P < 0.05).The relative abundance of dominant bacteria and fungi in the microbial community was different in different decay classes.Co-occurrence networks showed that the bacterial community in class I deadwood had higher complexity,while the fungal community in class IV deadwood had higher complexity.In addition,the growth of P.acutum increased the bacterial and fungal diversity of each class but decreased the bacterial diversity of class V and the fungal richness of class IV.The abundance of dominant bacteria and fungi in different decay classes of P.massoniana deadwood showed different responses to the growth of P.acutum,and the P.acutum had a greater effect on the composition of the bacteria community than that of the fungus community.Co-occurrence networks showed that the growth of P.acutum reduced the complexity of the microbial ecological network in deadwood.