Spatial And Temporal Distribution Of Soil Nutrient And Mechanical Composition Of Haloxylon Ammodendron In Jilantai

In this paper,we selected the artificial Haloxylon ammodendron with c-onstru ction years of 2a,5a,10a,15a and 30a in Jilantai as research objects.Through fie Id survey and laboratory,Spatial-temporal distribution of soil nutri-ents and mechan ical composition of Haloxylon ammodendron in different co-nstruction years.we fo und that:(1)Soil nutrient content in artificial Haloxylon ammodendron showed obvious stratification characteristics.From high to low is 0?10cm>10?20cm>20?40cm,the accumulation of nutrients in surface soil is more obvious.The soil nutrient content in different sampling positions in horizontal direction showed significant difference in 15a?30a.OM,AN,AP,AK,TN,TP and TK in roots are 30.8%,196.7%,22.5%,56.4%,22.2%,6.2%and 32.8%more than in shrubs.OM,AN,AP,AK,TP,TK and TN in shrubs are 30.8%,196.7%,22.5%,56.4%,22.2%,6.2%and 32.8%more than in inter-plant splace.Available nutrient content increased faster than total nutrient content among sampling sites.The main direction of soil nutrients source are east,west and south.Soil nutrient enrichment rate is higher in 15a?30a and lower in 5a?10a.It showed obvious"Fertile Island”effect in 15a?30a.Showed a trend of soil nutrient enrichment rate is that decreasing first and then rising with the increase of forest age.(2)The grain content of surface soil under artificial Haloxylon ammodendron forest form high to low is Sand>silt>clay.The content of sand grains ranged from 89.33%to 98.67%.Among them,the proportion of fine sand grains ranged from 49.92%to 66.87%,showing typical soil ecological characteristics in arid desert areas.The content of silt and clay in horizontal direction from large to small is root>inter-plant space>shurbs.The content of coarse particulate matter in horizontal direction from large to small is shurbs>root>inter-plant space.With the increase of the construction years of Haloxylon ammodendron,the enrichment rate of clay,silt,coarse sand and very coarse sand is on the rise,while that of very fine sand,fine sand and medium sand is on the decline.With the increase of construction years,the peak value of surface soil particles decreases,the sorting ability improves,and the erodible particles of wind erosion increase,which shows a good wind-proof and sand-fixing effect.(3)Based on correlation analysis,we found that the growth indexes of Haloxylon ammodendron were significantly correlated with the contents of soil organic matter,alkali-hydrolyzed nitrogen,total potassium and total nitrogen(P<0.05),but have no-significantly correlated with available phosphorus,available potassium and total phosphorus in soil(P>0.05).The growth indices of Haloxylon ammodendron are significantly correlated with the distribution of soil particles in root(P<0.05).The plant height and the crown width of Haloxylon ammodendron are significantly correlated with the erodible granules in topsoil.Therefore,Soil particle distribution is mainly affected by plant height and crown width of Haloxylon ammodendron.With the increase of forest age,the accumulation ability of fine particulate matter in roots increased,and the interception ability of plant height and crown width to coarse particulate matter increased.