Characteristics Of Vegetation Community And Soil Organic Carbon Changes In The Process Of Shrub Encroachment In Yunwu Mountain Grasslands,and Strategies For Shrub Encroachment Prevention And Control

Shrub encroachment in grasslands is a pivotal ecological shift observed globally in arid and semi-arid regions.This phenomenon not only alters the distribution pattern of herbaceous plants,impacting the premium development of animal husbandry but also modifies the spatial distribution of ecosystem resources,with a substantial impact on soil carbon storage.This research,focused on the grasslands of the Yunwushan National Nature Reserve in the Loess Plateau,investigates the changes in plant diversity and biomass in non-encroached and encroached grasslands during different growth seasons.Using biomarkers,the research also differentiates the contributions of plant-derived and microbial organic carbon to soil organic carbon accumulation during shrub encroachment.Furthermore,this study has established a scientific strategy to combat the expansion of shrub encroachment,offering an insightful method for the efficient utilization of grassland resources and the promotion of high-quality development in animal husbandry.The key research findings are as follows:(1)The process of shrub encroachment,although reducing plant biodiversity in grasslands,did not lead to significant disparities.The Shannon-Winner and Simpson indices of non-encroached grasslands exhibited high values during both the onset and peak of the growing season,with minimal fluctuations.In contrast,shrub-encroached grasslands displayed the lowest Shannon-Winner diversity index,Simpson dominance index,and evenness index at the beginning of the growth season,with these values dropping further during the peak of the growth season.(2)Shrub encroachment significantly influenced plant biomass and litter content.The above-ground biomass of plants in encroached grasslands surpassed that in non-encroached grasslands,particularly in the shrub patches.However,the trend in subsurface biomass varied across the growth season.Non-encroached grasslands exhibited higher subsurface biomass at the beginning of the growth season,while shrub patches in encroached grasslands displayed elevated subsurface biomass at the peak of the growth season.Moreover,litter content increased with the degree of shrub encroachment at the beginning of the growth season,indicating a greater competitive growth advantage in shrubs.(3)The phenomenon of shrub encroachment was found to bolster the accumulation of soil organic carbon,with microbial organic carbon displaying a more pronounced contribution than plant-derived organic carbon.In a detailed analysis,it was observed that at the onset of the growth season,bacterial organic carbon superseded fungal organic carbon in contributing to the soil organic carbon pool.However,this trend reversed at the growth season’s zenith,with fungal organic carbon assuming the leading role.A stratified analysis of soil layers revealed that in both non-encroached and encroached grasslands,the organic carbon content was richer in surface soil as compared to subsoil strata.(4)This study has successfully developed a shrub cutting device suitable for mountainous slope environments.The device uses a highly coordinated telescopic rod mechanism to ensure that the cutting component is always horizontal,thereby maintaining uniformity in the level of shrub cutting.Furthermore,the utilization of motor-driven horizontal and vertical adjusting rods enables multi-directional operation of the shrub cutting component,making the operation more efficient and economical.(5)In the current study,we implemented a strategy that involved pruning the aboveground parts of shrubs at the commencement of the growing season using a bespoke cutting device.Post-pruning,the area was covered with a 10-needle density black sunshade net for a duration of three months.Subsequent to this phase,any emerging branches and buds were manually removed,and the shaded conditions were sustained until the following growing season.This method elicited a mere 5% incidence of new shrub shoots,which displayed signs of wilting.Concurrently,the herbaceous plants under the shrubs exhibited vigorous growth,indicating that this technique could be effective in controlling shrub expansion and promoting the recovery of herbaceous plants in shrub-encroached areas.The successful implementation of this strategy underscores its potential as a robust tool for grassland management,thereby facilitating the high-quality development of animal husbandry.