Effects Of Different Mixing Patterns Of Guangxi Castanopsis Hystrix Miq.on Soil Properties

As one of the typical broad-leaved native species in Guangxi,Castanopsis hystrix has excellent material and high economic value,but pure forest planting often causes the problems of soil fertility decline and diversity reduction.Therefore,in this paper,four different types of stands,namely,pure Castanopsis hystrix forest(control),Castanopsis hystrix+pinus elliottii mixed forest,Castanopsis hystrix+Michelia macclurel mixed forest and Castanopsis hystrix+Mytilaria laosensis mixed forest,were selected to study the soil physicochemical properties,enzyme activity,microbial biomass and carbon under different mixing patterns.We studied soil physicochemical properties,enzyme activities,microbial biomass,carbon and nitrogen,and microbial diversity under different hybridization patterns,compared and analyzed the effects of different hybridization patterns on soil properties,and comprehensively evaluated the soil quality of the four types of stands.The study aimed to provide a scientific basis for the hybrid transformation of pure Castanopsis hystrix forests.The main results of the study are as follows:(1)The effects of different hybridization patterns of red vertebrae on soil physical and chemical properties were very significant.The soil water content of the four stands was significantly different in the soil layer of 20-40 cm,as follows:Castanopsis hystrix+Michelia macclurel>Castanopsis hystrix+pinus elliottii>Castanopsis hystrix pure forest>Castanopsis hystrix+Mytilaria laosensis,and the soil capacity of the four stands was significantly different in the soil layer of 0-20 cm and 0-40 cm,and increased with the deepening of the soil layer.The soil pH and total nitrogen of the four stands were significantly different in each soil layer,and the soil pH of the four stands fluctuated in the range of 4.06-4.32.The ranking of total nitrogen in the 0-40 cm soil layer was:Castanopsis hystrix+Michelia macclurel>Castanopsis hystrix pure forest=Castanopsis hystrix+Mytilaria laosensis>Castanopsis hystrix+pinus elliottii.There were significant differences in soil organic carbon between the four stands in the 20-40 cm and 0-40 cm soil layers,and the size relationship between the 0-40 cm soil layers was:Castanopsis hystrix+Michelia macclurel>Castanopsis hystrix+pinus elliottii>Castanopsis hystrix+Mytilaria laosensis>Castanopsis hystrix pure forest.(2)The effect of different hybridization patterns of red vertebrate on soil enzyme activity and microbial load was significant.5 indicators of soil catalase activity,sucrose enzyme activity,urease enzyme activity,acid phosphatase enzyme activity and soil microbial biomass carbon were significantly different in different soil layers of the four stands.Sucrase activity:Castanopsis hystrix>Castanopsis hystrix+pinus elliottii>Castanopsis hystrix+Michelia macclurel>Castanopsis hystrix+Mytilaria laosensis;Urease activity:Castanopsis hystrix+Michelia macclurel>Castanopsis hystrix=Castanopsis hystrix+Mytilaria laosensis>Castanopsis hystrix+pinus elliottii;Acid phosphatase activity:Castanopsis hystrix+Mytilaria laosensis>Castanopsis hystrix+Michelia macclurel>Castanopsis hystrix+pinus elliottii>Castanopsis hystrix pure forest;Soil microbial biomass carbon:Castanopsis hystrix+Michelia macclurel>Castanopsis hystrix+pinus elliottii>Castanopsis hystrix pure forest>Castanopsis hystrix+Mytilaria laosensis.(3)Different mixing patterns of Castanopsis hystrix had significant effects on soil microbial diversity.Bacteria had higher species abundance and diversity in Castanopsis hystrix+Michelia macclurel,while fungi had higher species abundance and diversity in Castanopsis hystrix+pinus elliottii,and overall the microbial abundance and diversity in the mixed forest showed a trend of higher than that in the pure forest.the main representative bacterial species groups in the four forest stands,at the phylum level,were Acidobacteria,Proteobacteria,Chloroflexi,Actinobacteria,Verrucomicrobia and Firmicutes,with other phyla accounting for a smaller proportion.The relative abundance of Verrucomicrobia was significantly higher than that of the other three forest types,and the first three phyla of Acidobacteria,Proteobacteria and Chloroflexi accounted for more than 80%of the overall phyla and dominated the soil bacteria.the relative abundance of the major fungi in the soil of the four forest types differed significantly at the phylum level and was dominated by Ascomycota,Basidiomycota,Mortierellomycota,Rozellomycota.The relative abundance of Basidiomycota phylum was significantly higher in the soils of Castanopsis hystrix pure forest and Castanopsis hystrix+Mytilaria laosensis forest stands than in other forest types.(4)Evaluation of soil quality in different stands based on principal component analysis showed that the soil quality of the four stands was ranked from highest to lowest:Castanopsis hystrix+Michelia macclurel(0.56)>Castanopsis hystrix+Mytilaria laosensis(0.47)=Castanopsis hystrix+pinus elliottii(0.47)>Castanopsis hystrix pure stand(0.45),and stepwise regression analysis of the selected representative indicators revealed that soil organic carbon and urease were the key indicators revealing soil The minimum data set(MDS)was well representative of the total data set(TDS).In conclusion,it can be concluded that the hybrid model of Castanopsis hystrix+Michelia macclurel can effectively improve soil physicochemical and biological properties and contribute to the overall quality of the soil.