| Natural oak(Quercus aliena var.acuteserrata)mixed forest,which accounts for a large proportion and are widely distributed in China,is the main forest vegetation type in the Xiaolong mountain region.It plays an important role in local soil and water conservation and environmental protection.Thus,it is of great importance to manage and protect the natural resource of oak mixed forests.However,due to natural disasters and human interference,natural oak forest has undergone different levels of degradation,it is urgent to adopt scientific and reasonable management techniques to restore the natural forests.This study was conducted in the natural oak mixed forests in Xiaolong Mountain,to compare and test management effects of different management models applied in the small classes of No.3 in Daganzi ditch of Baihua forest farm in Gansu province.Under the research project of "12th Five-Year Plan" ?Study and Demonstration of Technology for Sustainable Forest Management in Northwest North China ?,three types of management methods(close-to-nature management,structure-based management and secondary forest comprehensive cultivation)and control(unmanaged)trails were established in different plots.The four kinds of management methods were applied to 4 fixed plots of 20m×20m,and a total of 16 fixed plots were established.Electronic Total Station(TOPCON-GTS-602AF)was used to locate each tree with a DBH>5cm in each plot and tree species,diameter at breast height(DBH),crown width,height of tree were recorded and numbered.In September 2017,reinvestigation was conducted in all plots to measure the DBH,tree height,and crown width of all remaining trees.In addition,canopy characteristics of each stand were additionally measured and soil samples were collected for microbial community diversity analysis.Through the methods of spatial and non-spatial,static and dynamic,macroscopic and microscopic,single factor and comprehensive,the stand quality was analyzed from four aspects: stand productivity,stand structure,stand stability,and soil microbial community structure characteristics.Then the evaluation methods of ?-value rule and near-natural degree of forest quality influenced by the management disturbance were used tofurther explore the impacts of different management methods on the quality of natural forest stands of Quercus aliena var.acuteserrata,the study is to provide a theoretical basis for the scientific management of the natural forests of Quercus aliena var.acuteserrata.The main conclusions of this study are as follows:(1)Structure management can effectively improve the forest status.According to the univariate distribution of structural parameters,structured management can effectively adjust the horizontal structure of forest trees to make them tend to be randomly distributed and remain in a reasonable state for 4 years after management.It can significantly increase the tree speceis mingling,but other management methods have no obvious effect on it.Bivariate distributions of spatial structure parameter s showed that the management practices had no significant effects on the proportion of “optimal” microstructures(high-mixed with dominant woods,highly mixed with randomly distributed,and randomly distributed with dominant woods)in forest stands.Four years after the management,the proportion of forest trees with superior micro-structures(highly mixed with dominated woods,highly mixed with randomly distributed woods)increased in the structured managed forest stands and was significantly higher than that before the management.However,only the implementation of structure-based management has significantly reduced the proportion of trees with “disadvantageous” microstructures(non-randomly distributed with low-mixed,low-grade mixed with inferior wood),and the proportion of trees was also significantly lower than before.(2)Structured management and comprehensive cultivation of secondary for-ests red uced the proportion of trees with small and medium diameters in the forest,while nea r-natural management had no a significant impacts on it.Four years after management,the percentage of forests with medium and small diameters in the near nature and s econdary forests increased,and the proportion of trees with large-scale trees increased in the structured forest management;at the same time,it has also been found that thestructural management promoted the growth of the DBH of the small-diameter trees,while this was not found in other management methods and unmanaged forest stand.Both structured management and near-natural management can increase the number ofadvanced trees in the forest,but the tree mortality rate is the lowest in the former.(3)Both the structured management and the near-natural management have increased the leaf area index of the stand and the former also reduced the average leaf inclination of the stand.They both increased the photosynthetically active radiation in the stand.The former can effectively increase annual average growth and growth rate of stand volume,tree layer biomass and carbon storage.Forest status is also forecasted for 10 years after management,and we found the productivity of the structured forests was higher than other modes of operation and comparison.(4)Structure-based forest management can effectively improve the stability of forest.The stability of the forest was improved after the operation of structured forest management and near-natural forest management.The comprehensive cultivation of secondary did not improve the state of the forest.After four years of operation and implementation,the forest management status of the structured management was significantly improved,reflecting the enhanced stability of forest stands.(5)The plots under structure-based forest management is closer to the natural forest in terms of status.The difference between the status characteristics index of the structured forest management and zonal top-level community is the smallest,and the following is comprehensive cultivation of secondary forests and near-natural management,and the difference in the unmanaged forest stands is the largest,indicating that the results of structured management are superior.(6)Structural management significantly increased the proportion of soil-specific bacteria and fungi(OTU)species.At the level of gate classification,there was no significant effect on the richness and diversity of soil bacteria and fungi in each management method;while at the level of genus classification,it has significantly increased the diversity of soil bacteria.Structural management has significantly increased the Acidobacteria richness,which is beneficial to the growth of forest trees.However,the Ascomycota richness in the near natural management plots has increased significantly,reflecting the poor soil environment in the forest. |
PDF Full Text Request