The Dynamics Of Different Grassland Fine Roots And Their Effects On Soil Carbon Storage In Rocky Desertification Area

The fine root(diameter<2 mm)is the "sink" of plant nutrient,water transport channel and carbon storage.By decomposing carbon and mineral elements into the underground ecosystem,fine roots are a major source of soil carbon and nutrient storage.Rocky desertification area is a typical ecologically fragile area,and it is very weak to study the root dynamics of plant roots that affect carbon cycle in this vast area.In this study,Guizhou Grass Animal Agricultural Co.,Ltd.,the Youshanhe River farm,Guizhou Province Grassland Extension Station Dushan Grass Farm and the artificial and natural grassland of Guanling Shengshi Animal Husbandry Co.,Ltd.were used as research objects,and different research methods were adopted.Methods such as dynamic monitoring and field control experiments were carried out to study the following:(1)different grass root biomass,productivity,and turnover of research;(2)the relationship between the root dynamics and soil factors of different grassland in rocky desertification area;(3)study on the contribution of root system decomposition and turnover of different grassland ecosystem to soil carbon storage.The following results are obtained:(1)The dynamic changes of artificial grassland of Dafang,natural grassland of Dafang,natural grassland of Guanling,artificial grassland of Dushan,and natural grassland of Dushan were significantly changed with the month.The live fine root biomass and dead fine root biomass of five different grassland communities were single-peak,showing a trend of increasing first and then decreasing.The live and dead fine root biomass of natural natural grassland communities were in May and July respectively.The month reached its maximum,and the other four communities reached the maximum in September.The live and dead fine root biomass of five different grassland communities was mainly concentrated in the 0-10 cm soil surface.The distribution of fine roots in the community of Dafang and Dushan artificial grassland compared with the natural grasslands of Dafang,Guanling and Dushan is more shallow.The ratio of fine roots to total fine roots in the 0-10 cm soil layer of the Dafang,Dushan artificial grassland community and the natural grassland communities of Dafang,Guanling and Dushan were 72.29-83.57%and 57.78-80.52%respectively,and the beta values were 0.835-0.880 and 0.849-0.917.(2)The natural grassland communities of Dafang,Guanling and Dushan compared with the artificial and grassland communities of Dushan and Dushan,the root productivity decreased by 10.93%and 6.91%,and the root turnover rate of the Dushan artificial grassland community increased by 24.21%.The annual root productivity of the artificial grassland community was 22.50%higher than that of natural grassland,and the turnover rate was 15.63%higher.The fine root decomposition rate of artificial grassland community was faster than that of natural grassland,and the fine root turnover rate of artificial grassland community was slower than that of natural grassland,which were 1.53 and 1.31 times/a,respectively.A higher fine root turnover rate allows natural grassland communities to maintain soil nutrient conditions similar to artificial grassland communities.(3)The soil water content,bulk density,electrical conductivity,temperature,and pH of five different grassland communities were significantly different.The natural grassland communities of Dafang,Guanling and Dushan were significantly higher than those of the artificial and grassland communities of Dushan and Dushan.The soil pH increased significantly,but the soil water content decreased,but the difference was not significant.The soil electrical conductivity increased.Fine root decomposition rate,root biomass and soil water content,bulk density,electrical conductivity,temperature and pH were significantly correlated(P<0.05).In general,soil pH,temperature,and soil moisture are the most important factors affecting each variable.(4)Soil organic carbon,total N,and total P decreased with the increase of soil depth,and the soil nutrient content was the highest at 0-10 cm.The soil nutrient status of artificial artificial grassland is better than that of other four communities.The soil nutrients in the artificial and grassland communities of Dafang and Dushan were higher than those of natural grassland communities in Dafang,Guanling and Dushan.Fine root decomposition rate,root biomass and soil organic carbon,total N,total P,and total K have significant correlations.In general,soil organic carbon values and total N are the most important factors affecting the rate of fine root decomposition and biomass.(5)The soil organic carbon in the artificial artificial grassland,natural natural grassland,Guanling natural grassland,Dushan artificial grassland,and Dushan natural grassland all showed a decreasing trend with increasing soil depth.Soil organic carbon in the 0-10 cm soil layer.The content is significantly higher than the organic carbon content in the soil layers below it.The seasonal variation of soil organic carbon content in five different grassland communities showed a single peak change.The average organic carbon density in the natural grassland communities of Dafang,Guanling and Dushan was higher than that of the artificial and grassland communities in Dushan and Dushan,which were 3579.07 g/m~2 and 2911.31 g/m~2 respectively.The organic carbon density in natural grassland was 1.20 times that of artificial grassland.(6)0-10 cm soil carbon storage in natural artificial grassland,natural natural grassland,Guanling natural grassland,Dushan artificial grassland,and Dushan natural grassland were 3882.83 g/m~2,3932.67 g/m~2,3319.71 g/m~2,respectively.3099.79 g/m~2,3484.84 g/m~2;root biomass carbon storage is 712.25 g/m~2,1081.01 g/m~2,529.99 g/m~2,652.01 g/m~2,1112.74 g/m~2;roots enter the soil through decomposition and turnover The organic carbons were 51.41 g/m~2,154.79 g/m~2,57.31 g/m~2,71.38 g/m~2,and 40.69g/m~2,respectively.The root biomass carbon storage in five different grassland communities accounted for 24.71%,27.49%,15.97%,21.03%,and 31.93%of the soil carbon storage respectively.The organic carbon that enters the soil through decomposition and turnover of the root accounts for 1.78%,3.94%,1.73%,2.30%,and 1.17%of the soil carbon stock.(7)There is a positive correlation between soil organic carbon,soil water content,bulk density,and temperature of natural artificial grassland,natural natural grassland,artificial grassland of Dushan,and natural grassland of Dushan.The correlation coefficient is higher than 0.6;soil bulk density and electrical conductivity are the influence factors.The main factors of soil organic carbon in the natural grassland community and the Dushan artificial grassland community were soil temperature,and soil temperature was the main factor affecting the community organic carbon of community artificial grassland,natural natural grassland and natural grassland of Dushan.