Study On Characteristics And Restoration Mechanism Of Degraded Grassland In Xilamuren

In order to control grassland degradate and protect biolocical resources, keep a benign cycle of"Ecology-Society-Economy".With recovery ecology's principle and method as guide, field investigation and laboratory analysis were used to study grassland deteriorative characteristics, soil moisture physical characteristics, moisture conservation mechnasim, water restoration. Results are as following:(1)Xilamu-grassland is generally in a degradation state, with degradation level increasing, community species reduced, the species number of CK, light degraded , middle-degraded, heavily-degraded, extreme degradation were 38,31,26,18,13. Vegetation coverage, species height , above-ground biomass all showed lower trent. Compared with CK, 0-30cm soil bulk density of light, middle , heavily and extreme degradation increased 2.66%,6.3%,8.96% and 17.43%, meanwhile, soil mutrient content decreased at different degree.Soil height, coverage, above-ground biomass and biodiversity index were in positive correlation with soil nutrient.(2)The area was eroded seriously, sand-soil ratio of slope top, middle, and bottom were 42.1%,27.2%,17.6%. There existed exponential relationship between Soil bulk density and the steady infiltration rate(R2=0.9764), Rainfall is a major source of soil moisture in the area, correlation coefficient of soil water storage capacity and average annual rainfall was 0.7808, soil moisture vertical changes can be divided into active layer, sub-active water layer and stable layer, water annual and seasonal change were in line with the trend of precipitation changes.(3)Gravel and straw mulch cover can effectively inhibit soil surface evaporation, soil evaporation of 2-4mm diameter gravel covered was 81% of CK. Of different straw coverage, the inhibition rate of 100% coverage can reach up to 50%. Field test results show that the effect of 3cm thickness gravel covered soil water better; 0-30cm soil moisture content increased with straw covered, the amount of straw 5000 kg/hm2, soil moisture was 4% higher than CK. Soil surface and 5cm temperature can be fitted as sine function, the temperature adjusting effects of gravel, straw covered were insulation when temperature was cery low, cooling effect when in high temperature.(4) Simpson index, Shannon-Wiener index, Pielou index and Margalef index showed double increasing at different moisture gradient. man-made soil tillage measure can keep soil surface moisture at a heigh level of 15% for a long time.After irrigating, sea buckthorn, Ceratoides, Caragana survival rate were 65.7%,32.1%, 53.7% higher than CK, around the district,plant height increasde 10%, species number increasde 10%, coverage increased 5% , Biomass dry weight increase 135.4g/m~2.(5) Water is certain request when Alfalfa forage grass is in growth stage , rainfall and irrigation mainly affect less than 80cm layer soil moisture, 80-200cm layer soil moisture content is 8%.There was obvious correlation between Alfalfa productivity and irrigation volume ,the math model was: Y = 0.9025Q1.4732 (R2 = 0.94), there are still large room for alfalfa irrigated productivity ,the reality productivity depended on the measures of water and fertilizer.