Effects Of Biological Soil Crusts On The Stability Of Artificial Grassland In The Source Of The Yellow River

In order to understand the distribution characteristics of BSCs in alpine meadow and to explore the effects on vegetation and soil of degraded alpine meadow and artificial grassland,the degradation and restoration mechanism of alpine meadow were revealed from the perspective of BSCs.The degraded alpine meadow and artificial grassland with different planting years(2000,2004,2007,2014,2017)in Maqin County of Qinghai Province were selected to investigate the vegetation characteristics,soil physical and chemical properties and the distribution of soil microorganisms in the surface layer(0~5 cm)of the artificial grassland.The results showed that:1.BSCs species,coverage and thickness were different in artificial grassland with different planting years.BSCs which dominanted by moss,lichen and plaque were in the artificial grassland with long planting years,while only moss was mainly distributed in the artificial grassland with short planting years,but the thickness was larger.2.BSCs were very sensitive to total coverage and litter.Vegetation coverage was significantly correlated with BSCs coverage(P<0.01).High levels of litter coverage(>30%)could significantly reduce the BSCs coverage and thickness.Surface soil water content(0~10 cm)significantly affected BSCs coverage(P<0.01),while lower soil water content(20~30 cm)significantly affected BSCs thickness(P<0.01).3.BSCs increased the gramineous coverage,density and aboveground biomass,but they reduced the average height of vegetation and 0~10 cm underground biomass.4.BSCs play an important role in nutrient accumulation and pH regulation.They could significantly increase the available nutrients in the surface layer(0~5 cm)of the artificial grassland with long planting years and the total nutrients with short planting years.They reduced soil particle size and increased the content of fine particles(fine sand,clay powder).5.With the increase of planting years,the number of prokaryotic and eukaryotic microorganisms increased gradually.The number of eukaryotic microorganisms in the surface soil of grassland(0~5 cm)was larger than that of prokaryotic microorganisms.The diversity indices between prokaryotic and eukaryotic microorganisms were significantly different and the dominant species were Ascomycota and Proteobacteria,The beneficial microorganisms increased gradually with the increase of planting years and the microbial community structure gradually improved.In conclusion,BSCs had a promoting effect on recovery of vegetation and soil inartifical grassland.They accelerated the succession from artificial grassland to natural meadow.