Comparative Study On The Response Of Three Kinds Of Lawn Grasses To Soil Layer Thickness And Planting Density On Slope

Against the backdrop of rapid economic development,infrastructure construction has accelerated,resulting in a large number of slopes that are difficult to treat.There are common problems in slopes,especially high and steep slopes,such as poor soil fertility and insufficient supply of water and fertilizer,resulting in insufficient input of plant material and energy,low survival rate,and poor growth status;At the same time,there are also problems during the construction process,such as blindly meeting the early slope greening standards,reducing the slope protection performance and landscape benefits of vegetation in the later stage.Therefore,understanding the adaptability characteristics of commonly used plants to slope habitats and selecting plant species with strong adaptability and good landscape effects are crucial for the quality of slope restoration.This experiment focuses on three common slope greening herbaceous plants-Elymus dahuricus Turcz,Festuca elata Keng ex E.Alexeev,and Poa pratensis L.By simulating changes in soil layer thickness and planting density,the adaptability of three types of lawn grass in slope,especially in high and steep slope habitats,is compared and studied,in order to provide theoretical guidance for high and steep slope greening engineering.The main research findings are as follows:1.In the experiment of simulating different soil layer thicknesses in high and steep slope habitats,the results showed that at a soil layer thickness of 5cm,Elymus dahuricus sprouted only 6 days ago,with the highest germination rate of 42.48%.After 3 months,the height of the grass layer,underground biomass,root volume,and total root length all ranked first among the three lawn grasses.Its physiological and biochemical processes in vivo also had the strongest adaptability to the"drought rehydration"dynamic environment;At a soil layer thickness of 10cm,the changes in various indicators of Elymus dahuricus were similar to those at a soil layer thickness of 5cm.Higher fescue and bluegrass showed higher habitat adaptability;When the soil layer thickness is 15cm,tall fescue grows more vigorously,and its body’s regulation of water is strengthened,demonstrating stronger adaptability.The above results indicate that in steep slopes with thin soil layers,elymus can quickly cover green,reduce soil erosion on the slope,achieve landscape and ecological benefits,and demonstrate good adaptability;But in habitats with thicker soil layers,tall fescue has stronger adaptability to the environment.2.In the response experiment of three types of lawn grass to simulated three different slopes of sowing density,it was found that increasing sowing density can increase the germination number of lawn grass.When the sowing density is 20 g/m~2,the biomass,stem and leaf interception,and root volume of the aboveground and underground parts of lawn grass are greater than those of lawn grass with a sowing density of 10 g/m~2.However,when the sowing density increases to 40 g/m~2,all indicators of lawn grass decrease,This means that an excessively high planting density will actually intensify interspecific competition and reduce the comprehensive adaptability of lawn grass.The adaptation of three types of lawn grasses to slope is as follows:tall fescue>elymus nutans>bluegrass.High fescue exhibits the strongest habitat adaptability in slope habitats with slopes of 30°,50°,and 70°at a sowing density of 20 g/m~2.3.Through the construction of a comprehensive evaluation index system for slope greening benefits,it was found that Elymus nutans and tall fescue are two pioneer grass species with advantages in high and steep slopes:Elymus nutans has strong drought resistance,poor tolerance,rough leaf surface,and strong stem and leaf interception;Tall fescue grows vigorously,has uniform color,strong slope protection ability and landscape benefits,and has the strongest comprehensive adaptability.Although bluegrass has the worst adaptability in high and steep slope habitats,it also has prominent advantages such as developed root systems,strong soil fixation ability,and long green period.The above results provide a theoretical reference for selecting lawn grass types for different types of slopes.