Study On Vegetation Recovery And Soil Properties Of The Aerial-Seeding Region In Otindag Sandy Land

In this study,particularly begins its research based on the aerial-seeded region in Otindag Sandy Land.This paper,from 2013 to 2017 for the last five years,studied vegetation recovery of the regions seeded by aircraft in the year of 1999?2000?2001?2002?2005?2007?2008?2009?2011?2012 and 2013.The shifting sandy land remain unplanted by aircraft were kept as control.This 12 soil samples included different year treatment and control sand land were collected and the physicochemical properties were characterized in 2017.Adopting the method of substitution of space for time,we systematically analyzed species composition,quantitative characteristics,species diversity of the vegetation in the regions after aerial-seeded treatment.We also analyzed the inter-dependent relationship between the species.Meanwhile,we studied the interaction between the soil and the vegetation in different habitats in the same growth time.The aim of this study is to clarify the rehabilitation of vegetation and the variation of the species in the aerial-seeding region in Otindag Sandy Land and discuss the action of artificial vegetation on sand fixation and soil property changes.In general,the results provided the theory basis and the practice guidance for the restoration of sand vegetation and reconstruction of degraded ecosystem.The result of the study is summarized as follow:Firstly,the vegetation communities in the aerial-seeded region in Otindag Sandy Land were divided into the tree and shrub layer or the herb layer.After investigation,there were 17 species in the tree and shrub layer,belonging to 5 families and 8 genera.It was shown that 82.35% species in the research area consisted of Leguminosae,Rosaceae and Compositae.The number of the species on the hillsides facing wind was as high as10 species after 9-10 years of vegetation restoration.There were 95 species in the herb layer,belonging to 22 families and 63 genera.18.95% species in the research area consisted of Gramineae.And,in the ninth year of vegetation restoration,there were 43 species on the top of the dune.Secondly,in the tree and shrub layer,the height and coverage of vegetation communities of different functional types showed a trend of increasing in volatility.In the herb layer,that data showed a tendency to increase first,then decrease,and thenincrease again.In the tree and shrub layer,the height and coverage of Ulmaceae showed a trend of increase;In the herb layer,Chenopodiaceae,Leguminosae and Gramineae showed a tendency to increase first,then decrease,and then increase again.In the tree and shrub layer,the height of plant in windward slope reaching the maximum in the 8th year of recovery;In the herb layer,that height is in the 9th year.Thirdly,with the aerial sowing plant,Hedysarum laeve and Artemisia sphaerocephala grown very quickly in the preliminary stage of recovery,the coverage in2 nd recover year is clearly higher than the 1st year.The height and coverage of Ulmus pumila var.sabulosa have been increasing in the past 19 years of recovery.Astragalus adsurgens ‘Shadawang' tend to be short-lived and disappeared in the 9th year of recovery.With the original species,the height and coverage of Artemisia intramongolica showed a trend of increasing first and then decreasing.The density of Oxytropis gracillima indicate a significant increase.The frequency of Corispermum chinganicum,Bassia dasyphylla and Setaria viridis is relatively high.Fourthly,the Margarlef diversity index of family and genus showed a tendency to decrease after the first increase in arbor and shrub layer,but the index of species shows an increasing trend.The Shannon-Wiener diversity index,Simpson diversity index and Pielou evenness index showed a tendency to increase before decreasing and then to a smooth in family and genus level,and those indexes were less volatile in species lever.In the herb layer,the Margarlef diversity index and Shannon-Wiener diversity index were more volatile in family level,but the Simpson diversity index and Pielou evenness index were less volatile.In genus and species level,the Margarlef diversity index was tended to be volatile,which was inconsistent with Shannon-Wiener diversity index,Simpson diversity index and Pielou evenness index.Fifthly,in the tree and shrub layer,similarity coefficients at family levels were above average,which indicated the structure of the community was no obvious difference.Resemblance coefficients of families and species were 0.385-0.538 and 0.225-0.409 respectively,which belonged to middle-dissimilar lever.In herb layer,Resemblance coefficients of families were 0.211-1.000,with the coefficients of genus were0.175-0.979,the coefficients of species were 0.333-0.537,which were less balanced.Sixthly,the results show that the association degrees between shrubs,semi shrubs and trees were equal.There was a wide range of asymmetry between Salicaceae,Ulmaceae,Rosaceae,Leguminosae and Compositae,between perennial leguminousforage,complex class of perennial grasses and perennial forbs,between annual/biennial leguminous forage,annual/biennial grasses and annual/biennial forbs,between Leguminosae and Gramineae.The groups in the herb layer had a higher dependence degree to the groups in the tree and shrub layer.Seventhly,stability of vegetation in the tree and shrub layer was higher than that of single shrubs,semi shrubs and trees.Furthermore,in the tree and shrub layer,shrub and semi shrubs had a higher position and function than tree,and the status and role of Leguminosae were higher than other families,and the status and role of Hedysarum are higher than other genera.The absolute roles of Hedysarum laeve,Artemisia intramongolica and Ulmus pumila var.sabulosa were the most effective,and the relative roles of Hedysarum laeve,Hedysarum scoparium and Caragana microphylla were relatively higher in arbor and shrub layer.To the vegetation in herb layer,the stable degree of which was lower than that of annual/biennial grass,but it was higher than others.In the herb layer,the status and role of Gramineae were higher than other families,the Serratula was closely correlated to the Optimal parent sequence,the absolute roles of Serratula,Urtica,Lespedeza,Corispermum and Leymus were higher,and the relative roles of Serratula,Corispermum,Leymus,Urtica and Lespedeza were relatively higher.Lastly,the results showed that the shrubs and single shrubs had a greater correlation with soil p H,total phosphorus,total potassium content,coarse sand,soil moisture,and the trees had a greater correlation with soil bulk density,coarse sand,instant potassium content,soil p H value,soil total phosphorus content.Perennial legume forage had the greatest correlation with soil moisture content and p H value,Perennial grass,Perennial weeds and annual/biennial grass had the greatest correlation with soil moisture content and soil total potassium content.Annual/biennial leguminous grasses had the greatest correlation with Silt Sand(SS)and soil total potassium content.Annual/biennial forbs had the greatest correlation with Coarse Sand(CS)and soil total potassium content.