Effects of close-to-nature management of Plantation on the structure and ecological functions of different habitat speci�city taxa of soil microorganisms

Aims: To investigate the changes in community structure with different habit speci�city of soil microbial and the differences of effects on soil nitrogen mineralization during the near-naturalization process, as well as to evaluate the effects of planted forest on close-to-nature operations. Methods: Forest with 65-years succession sequence of near-naturalization was used as research plots in the Baxianshan National Nature Reserve at the eastern foot of Yanshan Mountain in the warm temperate zone in northern China. Three typical stages of near-naturalization, namely, pure Pinus tabulaeformis forest, mixed forest and near-natural forest, were set up with natural secondary forest without naturalization as a control. We also classi�ed soil microorganisms into three groups according to the degree of habitat speci�city: generalized, neutral and specialized. Soil physicochemical properties, enzyme activities, and rates of nitrogen mineralization processes were measured, and soil fungal and bacterial community structures were analyzed using high-throughput sequencing. Results: (1) total carbon, organic carbon, total nitrogen, nitrate nitrogen and ammonia nitrogen contents were higher in natural secondary forests than those in near-naturalized stands, while pH, effective phosphorus, total phosphorus and dry matter contents were the highest in the near-natural forest stage. Acid phosphatase and cellulase activities of natural secondary forest soils were signi�cantly higher than that of near-naturalized stands, but dehydrogenase and β-glucosidase activities and the rate of nitrogen mineralization-related processes were the lowest in natural secondary forests, (2) Under the same habitat speci�city, the fungal niche width was larger than the bacterial niche width, and increased with the increase of the degree of approaching naturalization, but was signi�cantly smaller than that of natural secondary forests. (3) The effect of near-naturalization on the spatial richness of microbial communities decreased with degree of habitat speci�city and showed a temporal decay (the difference in community structure was greater in the early stages than in the later stages). (4) The explanation of community structure by soil physicochemical and enzymatic activities decreased with habitat speci�city, pH was the dominant factor affecting the structure of fungal generalized and neutral taxa, urease activity mainly affects fungal specialized taxa, and the distribution of bacterial communities was mainly in�uenced by the chemical characteristics of soil carbon, nitrogen and phosphorus, (5) The structure of the dominant genera of each habit-speci�c group in the natural secondary forest was signi�cantly different from that of the near-naturalized forest, and the abundance distribution of the dominant genera well explained the differences in soil nitrogen mineralization processes. Conclusion: Generalist taxa of soil microbial were more pronounced to close-to nature development of planted forest. Close-to-nature operations have resulted in positive improvements in both soil nutrients and microbial community structure, but still differed signi�cantly from those in natural forests. but few been to further differentiate soil microbial according to the degree of their habitat speci�city During 65-years of close-to-nature management and restoration of the P. tabulaeformis plantation in Baxianshan National Nature Reserve, a successional sequence from P. tabulaeformis forest to mixed coniferous forest to near-natural forest was formed, which provided a valuable natural laboratory for studying the interactions between soil microbial communities and soil properties during vegetation restoration through the spatial instead of temporal method. In this study, we classi�ed soil bacteria and fungi into generalized, neutral and specialized taxa according to their distribution of niche width, and investigated their structure and distribution along the near-naturalization gradient in response to soil properties and the differences in the role of different taxa in soil nitrogen mineralization. The �ndings of the study will help to reveal the interaction mechanisms between the environmental adaptation heterogeneity of soil microorganisms and soil changes during the successional gradient of plantation forests, and will also provide a reliable reference and scienti�c theoretical guidance for the geotechnical control and sustainable management of plantation forests. controlled by the sliding window command of Fastp. Paired Clean-Reads were obtained by removing the terminal primer sequences using cutadpt software, Raw tags were obtained by merging them according to the overlap of paired-end sequences using the fastq-mergepairs command, Raw data quality was controlled by the sliding windows function of Fastp to obtain Paired-end Clean tags. OUTs clustering and species annotationCluster analysis was performed using UPARSE at the 97% similarity level, and the usearch command was used to remove a�ne sequences and singleton OTUs in the process. Each clustered OUTs was annotated into seven taxonomic classes of boundary, phylum, order, family, genus and species by the sine method through the 16s in silva or the ITS database in Unite. and the community abundance tables for each rank were obtained. The present study was carried out mainly on the generic taxonomic rank. habitat-speci�c group. Mapping was done using the R 4.0. 0 basic program package and ‘ggplot2’ package.