| The Zoige Plateau is located in the eastern margin of the Qinghai-Tibet Plateau and is an important pastoral area in China.It has important strategic significance for water conservation and biodiversity conservation in the Yangtze and Yellow River basins,and has important ecosystem services.In recent decades,affected by global climate change,as well as overgrazing and artificial drainage,the wetland area of the Zoige Plateau has been shrinking,grassland degradation has become increasingly serious,and large areas of desertified grassland have appeared.After the implementation of the grazing and wetland protection project in recent years,the desertification trend of grassland has been curbed,and some desertified grassland has been restored.In this study,the Zoige alpine desertification grassland was used as the research object,and the time series sample plots were restored by establishing desertification grassland（recovery was 1 year,2 years,4 years,6 years,8 years,unrecovered and not degraded）.To study the changes and correlations between plant and soil properties during the restoration of desertified grassland.Explore the recovery mechanism of desertified grassland.Research indicates:（1）With the increase of recovery period,the desertification grassland changed from a single restoration species community to a natural community,and the vegetation coverage,vegetation biomass,species number,root length,root surface area and root projection area increased significantly.（2）With the increase of recovery years,the physical and chemical properties of the soil have been significantly improved.After 8 years of recovery,soil bulk density,soil water content,soil maximum water holding capacity,aggregate mass average diameter（MWD）,and average geometric diameter（GWD）were significantly improved and recovered,which was significantly higher than that of unrecovered treatment.The soil p H did not change significantly.The soil nitrate nitrogen,total phosphorus and available potassium increased significantly with the recovery period,and reached the maximum after 8 years of recovery,which were 30.42±3.16mg/kg,0.59±0.01g/kg,144.17±3.63 mg/kg.（3）The recovery process accelerated the accumulation of litter and humus in the grassland,and the soil enzyme activity and soil microbial biomass carbon and nitrogen increased significantly,showing an increasing trend with the increase of recovery years.There were no significant differences in the activities of the five soil enzymes after recovery to 8 years（≥8 years）and no degradation treatment,β-1,4-glucosidase activity andβ-1,4-N-acetylglucosidase increased by 151.67μmol kg-1h-1and 39.55μmol kg-1h-1and the increase rate was 98.05%and 93.31%respectively after 8 years of recovery.The acid phosphatase activity increased from5.17μmol kg-1h-1to 79.61μmol kg-1h-1,the increase rate was 93.5%,and the polyphenol oxidase activity increased by 67.46%.Peroxidase activity increased by75.68%.（4）Correlation studies show that there is a significant correlation and interactivity between grassland vegetation and soil properties during the restoration process,and there is some correlation between the change cycle and the sequential.The first significant changes in the recovery process are biomass,coverage,species quantity,and abundance,as well as physical indicators such as soil bulk density and porosity,and changes in soil structural indicators such as soil MWD,GWD,and intermediate-grained aggregates occur after this.The last change is the chemical biological nutrient index of organic matter,microbial carbon and nitrogen and the indicators of plant underground roots.The time for significant changes in these indicators is often restored to a time gradient of 4 years（≥4 years）or 6 years（≥6years）.（5）When the recovery time reaches 8 years（≥8 years）or more,the fenced grassland will return to the state of healthy grassland,and moderate grazing activities can be carried out at this time.During the grazing process,we should pay attention to the regular monitoring of vegetation species richness,vegetation biomass,soil bulk density and agglomerate stability to avoid grassland degradation caused by overgrazing,which will be more conducive to the effective prevention and control of desertification of Zoige alpine grassland.restore. |
