| The promotion and cultivation of Jujuncao(Pennisetum giganteum z.x.Lin)is one of the research hotspots in recent years.Planting in sandy areas Jujuncao can not only provide high-quality pasture,but also prevent wind and sand.It has great benefits for the local economy,society,and ecology,and has broad Research prospects.This study is based on four different configurations of Jujuncao plots in wind-eroded observation sites in the Liuguai Shatou of the Ulan Buh Desert.The study focused on the growth characteristics of the Jujuncao in the desert region using bare sand dunes.The characteristics of wind-sand flow transport in different configurations of macrophytes and the potential wind-and sand-fixing capacity reflected by the root distribution are analyzed.The results are as follows:(1)The height of the Jujuncao was 145.72-182.82cm at maturity,the average basal diameter was 2.37-2.98cm,and the mean height was 54.67-80.5cm after lodging.The yield of macro-grass was 6.69-13.27t/hm~2,and the ratio of root to shoot of macro-grass was 0.27-0.76.The underground biomass increased with the increase of slope position.Underground biomass showed a decreasing law with increasing depth,mainly distributed in the depth of 0-20cm,and the root biomass per unit volume was distributed in the depth of 0.16-0.50 g/cm~3.The horizontal gradients all decreased with the increase of horizontal distance.The root content within 30cm of horizontal distance accounted for 69.62%-75.65%of the total content,and the root volume per unit volume of horizontal biomass was 0.44-0.23 mg/cm~3.(2)Under the same conditions,root system RV,RLD,RND correspond to the root system at the bottom,middle,and slope.The standard root densities in the middle,top and bottom of the slope are 2.62,3.32,and 3.05.Therefore,the order of the potential sand-fixing ability of the roots at different slope positions is:bottom-slope>slope-bottom>slope-top.(3)The roughness of year-round,year-old,year-old and year-old stubble plots of wind erosion are 16.98cm,12.89cm,5.39cm and 1.49cm,respectively.Wind erosion has one year,two years,and one year.The average wind speed reduction ratios for wind speed kept in the year and 2 years were 65.91%,55.03%,41.83%,and 29.02%.Four kinds of Jujuncao plots can play a good role in controlling the surface sediments.The wind-resistance effects of the four macro-grass plots are:wind erosion one year>wind erosion two-year>wind erosion one year>Wind erosion stayed for two years.(4)Near the surface of 100cm,the sediment transport rate of naked dunes is a logarithmic decreasing rule,and more than 85%of the content is concentrated below30cm.The trend of the percentage of accumulated sand accumulation in stubble plots with height is similar to that of bare sand dunes,and they are all logarithmically decreasing,and 80%of accumulated sediment concentration is concentrated in 0-30cm.The protective effect of the wind erosion at 0-4cm near the surface is best,and that of the 4-30cm wind erosion is best.The order of the sand fixing effect of four macro-grass plots within 0-30cm on the surface is wind erosion one year>wind erosion two-year plant>wind erosion one year remaining>wind erosion two years remaining stubble,average sand fixation for all types of macro-grass plots The effect is more than 80%.(5)Within two years after castration,the Jujuncao areas can maintain a good effect of windbreak and sand fixation.In the third year after castration,grassland plots have basically lost their protective effect,and the protection time of plant plots remains to be studied. |
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