Response Of Degraded Alpine Wetland To Mowing And Reseeding

In this paper,we chose the Yellow River source area as the study area,and took alpine degraded wetland as object of the study.Short-term mowing and resowing experiment were respectively carried out in the moderate and severe degradation areas of the degraded alpine wetland.Through investigating the effects on the community characteristics of vegetation and soil nutrition,we explored the causes of alpine wetland degradation and the limiting factors in the process of recovery by resowing.The main research conclusions are as following:1.With the more mowing,vegetation height,coverage and diversity index showed a trend of decrease,but there were no significant differences among three kinds of mowing intensity(P>0.05).The content of physical clay less than 0.01 mm presented the tendency of decrease on the whole.The soil bulk density increased gradually,and there were no significant differences among various mowing intensities(P>0.05).In mowing experiment,annual water content of 20 cm deep soil was higher than that of 10 cm deep soil.With the more mowing,the water content of10 cm and 20 cm deep soil decreased gradually,and the annual average temperature of 5 cm,15 cm and 25 cm deep soil decreased gradually.2.In mowing experiment,soil nutrient and pH reduced gradually in the vertical direction.With the more mowing,soil nutrient and the pH decreased gradually,with no significant difference(P>0.05).Actinomycetes are dominant in soil microbes of degraded alpine wetland.In the vertical direction soil microbial quantity in the surface soil was greater than that of the other layers.The microbial quantities under different mowing intensity had no significant differences(P>0.05).3.In the reseeding land,along with the increase of reseeded forage plant quantity,soil texture increased gradually,and soil bulk density decreased gradually.Overall soil moisture content in the vertical direction was gradually increasing.With the increase of reseeded forage plant quantity,soil moisture content increased gradually,and soil moisture content in the 0 to 10 cm deep surface layer of bare land was significantly different from that of land with more reseeded plants(P<0.05).4.In the reseeding land,overall soil temperature in the vertical direction gradually reduced.With the increase in number of plants,soil temperature graduallyincreased.Soil temperature in the 0 to 10 cm deep surface layer of bare land was significantly different from that of land with more reseeded plants(P<0.05).Soil nutrients in the vertical direction were gradually increasing.With the increase in the number of reseeded forage plants,total K2 O,available K and pH decreased,and available K and pH in bare land were significantly different from that of land with more reseeded plants(P<0.05).Total N,total K2 O,alkaline hydrolysis N,available P and organic matter increased,and the total N,available P and organic matter in bare land were significantly different from that of land with more reseeded plants(P<0.05)5.In the reseeding land,soil microorganisms in the vertical direction gradually reduced.With the increase in quantity of reseeded herbage plants,the number of soil microbes from bare land to the land with more reseeded plants increased.6.Taking eight indicators with significant differences in different plant density of for factor analysis,the results showed that the soil moisture,soil temperature and soil electrical conductivity were the dominant factors restricting plant density in reseeding wetland.