Evaluation Of Vegetation Restoration Effects Of Coastal Mud Flats In The Yellow River Delta Based On Micro-topography

The Yellow River Delta Coastal Beach has a wide distribution of saline-alkali bare land.In order to increase its vegetation coverage and explore suitable vegetation restoration models,in the coastal beach flat area,simulate the setting of S-shaped,Strip-shaped,Pinshaped,Crescent-shaped,Step-shaped and Dense strip-shape.Six kinds of micro-topography transformation modes,such as,dense strips,and the bare land of bare beaches as a control,compare and analyze different micro-topography through the dynamic observation of soil water and salt dynamics,physical and chemical properties,and plant growth conditions of the six kinds of micro-topography transformation modes The soil volume and surface roughness index of the reconstruction model are analyzed and evaluated using principal components and fuzzy mathematics membership function method to evaluate the vegetation growth status and soil improvement effects of the six micro-terrain reconstruction models.The results showed that:(1)The micro-topography of the light beach improved the surface roughness,increased the seed retention rate,and formed a warm zone at the bottom of the pit to promote seed germination and increase the vegetation coverage.The modification of micro-topography significantly affects the physical and chemical properties of soil and the growth of vegetation.(2)The micro-topography is transformed in the warm area formed at the bottom of the pit to promote the growth of the pioneer plant Suaeda salsa,which grows on the bottom of the pit;the biomass,crown width and density of the S.after the micro-topography transformation,The coverage showed a significant increase trend,the crescent shape has a better effect on vegetation growth,and the vegetation coverage is as high as 98.21%.Observation of water and salt dynamics: After the micro-topography is modified,the water content at the bottom of the pit is significantly increased and the salt content is significantly reduced compared with bare land.In addition,the soil water content at the bottom of the pit is significantly higher than the top of the mound.The soil water content is the lowest in April 2020,and the water content in the pit is the highest in October 2020,and the salt content is the highest.Moisture content in October 2020: Crescent-shape> Strip-shape> Step-shape> Pin-shape> Dense stripshape> S-shape>bare land.The lowest salt content in October 2020 is bare land> Dense stripshape>Strip-shape>S-shape>Pin-shape>Step-shape>Crescent-shape.Based on the dynamic observation of soil physical and chemical properties,soil bulk density is significantly reduced after different micro-topography is modified,and capillary porosity,total porosity,capillary water holding capacity and saturated water content are significantly increased.The product shape has the best effect on soil bulk density,porosity,and water holding capacity.After the modification of different micro-topography,the soil nutrient increased significantly compared with bare land,and the nutrient of the bottom of the pit was significantly higher than that of the top of the hill,and the strip shape had the best effect on soil nutrient improvement.(3)Through the calculation of the coefficient of variation of the six micro-topography modification modes,the coefficient of variation of soil chemical properties is relatively large,and the coefficient of variation of soil total nitrogen content is as high as 60.66%,and the coefficient of variation of soil physical properties is small.The chemical properties are better than the physical properties.The main indicators for evaluating the effect of vegetation restoration after micro-topography reconstruction can be divided into three categories,one is plant growth indicators,the other is soil bulk density and porosity and other indicators,and the third is earthwork and surface roughness.Correlation analysis shows that soil nutrient indicators are significantly positively correlated with plant growth status(P<0.01),porosity,water holding capacity and other indicators are significantly positively correlated with plant growth status(P<0.05),and bulk density is significantly negatively correlated with vegetation growth status(P<0.05).(4)The growth status of Suaeda salsa and the soil improvement effect of different micro-topography reconstruction models are significantly different.The Crescent-shaped pattern can significantly reduce soil salinity,which is beneficial to promote vegetation restoration;the Strip-shape can significantly increase soil nutrients;the Dense strip-shape can significantly increase soil porosity and water storage,and reduce soil bulk density;the Sshaped pattern is useful for vegetation restoration and soil The improvement effect is moderate.The Step-shape model is better in terms of soil improvement,but consumes the highest amount of earthwork and the most economic cost;the Dense strip-shape performs the worst in terms of vegetation restoration and soil improvement.The comprehensive evaluation of the vegetation restoration effects of the six micro-terrain reconstruction modes is: Crescentshape>Strip-shape>Pin-shape>Step-shape>S-shape>Dense strip-shape>Bare land.It is suggested that the S-shape should be the next best for the micro-topography of the Yellow River Delta coastal beaches,and the Dense strip-shape may not be adopted.When transforming the micro-topography,the Crescent-shape is first considered,followed by the Strip-shape,the Pin-shape and the Step-shape.It is hoped that the micro-topography site preparation technology will provide technical support for the restoration of the tidal flat vegetation in the Yellow River Delta.