Study On Soil Physical And Chemical Properties And Meadow Community Biomass In Alpine Meadow Area Of Mira Mountain

In this study,the four slope directions of Mira Mountain,with an altitude of4500-5000m,are the study area,namely,the shady slope,the sunny slope,the semi shady slope,and the semi sunny slope.The altitude interval is 100 m,and the setting size is 20 m×20 m sample plot is used to collect soil and vegetation samples in each sample plot using the five-point sampling method.In each sample plot,undisturbed soil and aluminum box soil are sampled from three soil layers of 0-10 cm,10-20 cm,and 20-30 cm,and in each sample plot,20 cm is used×20 cm for aboveground biomass collection and underground plant root collection.The following conclusions are drawn through indoor experiments to determine soil physical and chemical properties and analyze aboveground and underground biomass:(1)The ranges of variation in soil bulk density,total porosity,capillary porosity,non-capillary porosity and soil aeration for different slope orientations at different elevation gradients were 0.47-1.14 g/cm~3,59.98-86.14%,57.71-82.25%,1.47-4.62%,12.79-45.44%for shady slopes,0.58-1.04 g/cm~3,58.45-84.40%,55.58-82.54%,0.85-4.81%,14.96-41.08%for sunny slopes;0.30-0.99 g/cm~3,59.29-79.14%,55.07-76.39%,1.33-4.60%,23.33-46.90%for semi-shady slopes;and 0.71-1.00 g/cm~3,52.57-90.71%,55.58-83.54%,0.85-4.81%,and 11.61-32.30%for semi-shady slopes.The soil bulk density increased with the increase of soil depth on the semi-negative slope at 4500 m and 4700 m and on the semi-positive slope at4800 m.The total porosity and capillary porosity of the four slopes generally decreased with the increase of soil depth;the non-capillary porosity showed no obvious pattern with the change of soil layer;the soil water content,saturation water content and capillary water holding capacity all increased with the increase of soil depth.The soil water content,saturated water content and capillary water holding capacity all decrease with increasing depth of soil layer.(2)There is no obvious pattern in the change of soil alkaline solubility N with soil depth,except for Yang slope,which increases with soil depth,and the other three slopes;effective phosphorus P and fast-acting K decrease with soil depth in general;soil organic matter,total N and total K decrease with soil depth in general;total P increases with soil depth;there is an obvious spatial autocorrelation phenomenon among soil physical and chemical properties.There are obvious spatial autocorrelations among soil physical and chemical property indicators.The spatial autocorrelation among soil physical and chemical properties was obvious.In general,the surface soil(0-10 cm)of Mira Mountain had better soil nutrient content;alkaline soluble N and total N content half-positive slope>negative slope>half-negative slope>positive slope;effective phosphorus content negative slope>half-positive slope>half-negative slope>positive slope;fast-acting K and organic matter content half-negative slope>half-positive slope>negative slope>positive slope;total P content half-negative slope>positive slope>half-positive slope>negative slope;total K content positive slope>half-positive slope>half-negative slope>negative slope.(3)The Shannon-Wiener index is higher on the half-negative slopes at 4700m(2.11)than on the rest of the elevation gradient,the Margalef index is higher on the half-positive slopes at 4700 m(1.44)than on the rest of the elevation gradient,and the Pielou index is higher on the half-positive slopes at 5000 m(0.99)than on the rest of the elevation gradient.Wiener index showed that half-positive slope>positive slope>shady slope>half-shady slope;Margalef index showed that half-positive slope>half-shady slope>positive slope>shady slope;Pielou index showed that positive slope>half-positive slope>half-shady slope>shady slope.(4)The shady slope,sunny slope,semi sunny slope and semi shady slope of Mila Mountain have complex geographical elements and obvious temperate characteristics,but the alpine meadow is rich in species diversity.The species diversity of sunny slope and semi sunny slope communities dominated by Kobresia alpina,Gentiana gentiana,Polygonum sibiricum,Gentiana Fried Dough Twists macrophylla,Desmodium sibiricum,and Ganoderma lucidum in Tibet is better than that of shady slope and semi shady slope vegetation communities dominated by Kobresia robustum,Potentilla,Edelweiss,and other clusters.The total biomass of the meadow community on the shady slope of Mira Mountain is 338.05-1020.50 g/m~2,the aboveground biomass of the community is 74.24-155.10 g/m~2,and the underground biomass of the community is 226.45-933.70 g/m~2;The total biomass of the meadow community on the sunny slope is 473.35-1057.83 g/m~2,the aboveground biomass of the community is 87.20-21.25 g/m~2,and the underground biomass of the community is 328.80-863.00 g/m~2;The total biomass of the semi-sunny meadow community is 391.65-1034.65 g/m~2,the aboveground biomass of the community is 69.50-185.30 g/m~2,and the underground biomass of the community is283.40-914.55 g/m~2;The total biomass of the semi-shady meadow community is477.45-897.25 g/m~2,the aboveground biomass of the community is 86.95-57.75g/m~2,and the underground biomass of the community is 319.70-767.15 g/m~2.Aboveground biomass sunny slope>semi-sunny slope>semi-shady slope>shady slope,underground biomass shady slope>semi-sunny slope>sunny slope>semi-shady slope,total biomass sunny slope>semi-sunny slope>shady slope>semi-shady slope.The underground biomass in the study area is higher than the aboveground biomass,and the biomass on the sunny slope is higher than that on the shady slope.In terms of soil physical properties,in different slope directions and different elevations,the four slope directions of Mira Mountain have strong water storage and water retention capacity except for the shady slope.In terms of soil available and total nutrients,the soil structure in the high altitude area of Mira Mountain is poor,the soil available nutrients are seriously lost,and the underground biomass of the four slope community species is much higher than the aboveground biomass,indicating that the dominant species distribute more biomass to the root system,which is beneficial to absorb soil nutrients and better adapt to the alpine climate.