Dynamic Analysis Of Soil Bacterial And Enzyme Activities And Physicochemical Properties In Larix Gmelinii

Taking four different Larix gmelinii forest types in Black-billed grouse nature reserve of Heilongjiang Central Station as the research object,the changes of soil physical and chemical properties,soil enzyme activity,soil bacterial community structure and diversity in different Larix gmelinii forest types were discussed.Four different Larix gmelinii forest types(Betula platyphylla-Larix gmelinii forest,Rhododendron dauriczcm-Larix gmelinii forest,pure forest of Larix gmelinii and Larix gmelinii Plantation)were selected for sampling according to seasons,and the soil physical and chemical properties and enzyme activities(Catalase,Acid phosphatase,Urease,Sucrase,Cellulase)in different seasons were measured,At the same time,the changes of soil bacterial community structure and diversity in different Larix gmelinii forest types were analyzed to explore the seasonal changes of soil physicochemical and enzyme activities and their relationship with soil bacterial community structure and diversity.The results showed that soil physical and chemical properties and enzyme activities were significantly different in different forests and seasons,and the change trend was also different,which was related to the accumulation of litter and the difference of vegetation types;Soil acid phosphatase is greatly affected by soil total phosphorus,total nitrogen and available potassium;Soil catalase was positively correlated with total nitrogen,available nitrogen,available potassium and available phosphorus;Soil invertase was significantly affected by available phosphorus and available nitrogen;Soil urease and cellulase were most affected by soil organic carbon content.The results of principal component analysis(PCA)showed that there were significant differences in soil enzyme activities and soil physical and chemical properties among the four Larix gmelinii forest types.Principal component 1 could explain more than 50% of the variance variables,and the factors affecting different Larix gmelinii forest types were different.High throughput sequencing was used to determine the soil microorganisms of four different Larix gmelinii forests.The internal relationship between soil microbial diversity and soil environmental factors was discussed by analyzing the change law of soil bacterial community composition and diversity.The results showed that there were significant differences in soil physical and chemical properties of different Larix gmelinii forest;The diversity indexes of soil bacteria Ace and Chao had no significant difference among the soils of different forest types.The total number and abundance of soil bacteria were the highest in Larix gmelinii plantation and the lowest in pure forest of Larix gmelinii;Shannon index and Simpson index analysis showed that the diversity of soil bacterial community in Larix gmelinii plantation was the largest,while that in Betula platyphylla-Larix gmelinii forest was the smallest,and the difference was significant;Correlation analysis showed that Chao index was significantly positively correlated with soil available phosphorus,and Evenness index was significantly positively correlated with soil total phosphorus;Canonical correlation analysis showed that there were significant differences among the four forests,and there were different degrees of correlation between soil bacterial group structure and soil physical and chemical properties.It can be seen that soil environmental factors were important factors affecting soil bacterial diversity in different Larix gmelinii forest.Bradford method was used to determine the content of soil glomalin-related protein in four Larix gmelinii forest types,analyze the change law of soil glomalin-related protein contents under different Larix gmelinii forest,and then analyze the relationship with soil physical and chemical properties and soil enzyme activity.The results showed that the content range of total glomalin-related protein(T-GRSP)was between 11.91 mg/g~18.05 mg/g,the content of easy to extract glomalin-related protein(EE-GRSP)was between 5.7 mg/g~7.03 mg/g,the ratio of EEGRSP/T-GRSP was between 19% ~ 33%.There was a significant correlation between the content of glomalin-related protein and soil physical and chemical properties.The main factors affecting the content of T-GRSP are carbon nitrogen ratio,total nitrogen and available nitrogen.The main factors affecting the contents of EE-GRSP were available phosphorus,available potassium and total potassium.In addition,the content of glomalin-related protein in different forests was very different.Soil sucrase activity significantly affected the content of glomalin-related protein,and other enzyme activities also affected the content of glomalin-related protein to varying degrees.This study shows that there were significant spatial differences in the content of glomalin-related protein among different forests,and there were varying degrees of correlation with the physical and chemical properties of soil.Therefore,it can be seen that soil physical and chemical were important factors in regulating the contents of glomalin-related protein,which confirms the previous research and provides a reference basis for local soil quality evaluation.