Effects Of Salix Psammophila Sand Barriers On Soil Nutrients

Salix psammophila sand barriers are one of the main measures to prevent and control desertification in northwest China and Inner Mongolia.It plays an active role in windbreak and sand fixation,soil improvement and vegetation restoration.Understanding the influence of Salix psammophila sand barriers on soil are conducive to the selection of pioneer species for subsequent sand control,and provides basic data and scientific basis for soil quality evaluation in the region after Salix psammophila sand barriers control.This study takes the peripheral soil of the stable sand buried part of the Salix psammophila sand barriers on both sides of the sand-crossing highway in Kubuqi desert as the research object.Through field investigation and sampling and indoor analysis,C,N,P contents and ecological stoichiometric ratio characteristics of the peripheral soil of the stable Salix psammophila sand barriers buried part are studied.The main conclusions are as follows:(1)The contents of available phosphorus,available potassium,total available phosphorus and total available potassium in the soil surrounding the mechanical sand barrier increased gradually within 1-3 years after the sand barriers were set,and reached the maximum nutrient content in 3 years,and showed a decreasing trend in the following4-10 years;The contents of alkali-hydrolyzed nitrogen,total available nitrogen and organic matter in the soil around the barrier fluctuated and increased with the increase of the setting years,and the maximum contents of alkali-hydrolyzed nitrogen and organic matter appeared in the 7 and 8 years after the laying of the barrier.The total available nitrogen content of soil around the barrier keeps increasing with the increase of the laying years.Five years after the setting of sand barriers are the time inflection point of the nutrient change of mechanical sand barriers.(2)There was strong spatial heterogeneity of soil nutrients around barriers at different slope positions.In the early stage of sand barriers setting,the nutrient contents of different slope sites were significantly different.The nutrient contents of alkali-hydrolyzed nitrogen,total available nitrogen,organic matter and total available phosphorus were in the order of bottom > middle > top,while the content of available phosphorus,available potassium and total available potassium were higher in the middle.(3)The ecological stoichiometric ratio(C/P and N/P)fluctuated and increased with the increase of sand barriers setting years,while(C/N)fluctuated and decreased with the increase of sand barriers setting years.There was no significant difference in ecological stoichiometric ratio between different slope positions at the initial stage of sand barriers setting.(4)Through RDA sequencing diagram analysis,it can be seen that only available K and C/N ratio are positively correlated with slope position in the process of mechanical sand barriers protection.Alkali-hydrolyzed nitrogen,available phosphorus and total available phosphorus were positively correlated with the setting years of sand barriers.Through principal component analysis,soil nutrients at different setting years and slope position of sand barriers were comprehensively evaluated.It was found that with the increase of setting years and the change of slope position,the comprehensive score showed an increasing trend,and the nutrient comprehensive score reached the highest at10 years of setting.During 1-5 years of sand barriers setting,slope position had a significant effect on nutrients,and the nutrient comprehensive score of slope bottom was the highest on different slope positions.