Study On The Growth Responses Of Typical Desert Plants To Artificial Consolidation Layer Of Desert Surface

Desertification has led to land degradation characterized by wind erosion.The arid and semi-arid areas in northern China are severely affected by desertification and the ecological environment is deteriorating gradually.The study of new methods of desertification control has become an urgent need in arid and semi-arid areas.It is a new idea for ecological construction in desert areas by constructing artificial consolidation layer on the desert surface to improve soil properties and restore ecological vegetation.In this paper,the field sampling and plot experiments of desert plants were conducted in 2016-2017 in the Hobq Desert.The improvement effect of sandy soil under soil crust was studied,and the responses of a variety of desert plants to artificial consolidation layer,as well as the interaction mechanism and timeliness rules between artificial consolidation layer and desert plants were explored.The research results are of great significance to ecological vegetation restoration,ecological environment construction and desertification control in desertified areas.The main results are outlined as follow:(1)The difference of soil crust and underlying soil layers with different soil crust types were revealed.From physical crust to algal and moss crusts,the thickness,water content,macro-aggregate(>250 ?m)content,organic matter content,microbial biomass,and enzyme activities of the soil crusts gradually increased,while the bulk density of the soil crusts decreased.Meanwhile,the physicochemical and biological properties of the soils below the algal and moss crusts were significantly ameliorated when compared with the physical crust.Moreover,the amelioration effects were significant in the upper horizons(approx.0-12 cm deep)and diminished quickly in the deeper soil layers.(2)The improvement effect of artificial consolidation layer on soil properties was discussed.Using fly ash and PAM to construct artificial consolidation layer,the formation of artificial consolidation layer effectively improved the pore structure of soil,significantly reduced soil bulk density,increased the porosity of soil capillary and the soil water holding capacity.The artificial consolidation layer caused the increase of soil pH,electrical conductivity,total nitrogen and total phosphorus content.The increase level was increasing with the amount of the use of fly ash,but it was not significant.By principal component analysis,the optimum ratio of soil improvement was 10%fly ash and 0.012%PAM combination.(3)The artificial consolidation layer constructed by fly ash and PAM postponed the emergence time of Artemisia ordosica,and inhibited the growth of Artemisia ordosica in 2016 in different degrees,which increased with the rising usage of fly ash.However,the low and medium fly ash ratio groups could ensure the growth of the ground diameter of Artemisia ordosicoa.The low fly ash ratio group had no significant negative effects on the total fresh weight,aboveground fresh weight,underground fresh weight and underground fresh weight of Artemisia ordosica in September and October in 2016.The optimum ratio for the emergence and growth of Arteisia ordosica was 5%fly ash and 0.006%PAM combination in 2016.(4)Compared with 2016,the plant height,ground diameter and leaf number of Artemisia ordosica showed an upward trend,and the inhibitory effect of fly ash on Artemisia ordosica growth was gradually weakened.Especially in the artificial consolidated layer constructed by low and medium fly ash ratio groups,the positive effect of fly ash outweighed the negative effect.The optimum ratio of Artemisia ordosica growth in 2017 was 5%fly ash and 0.006%PAM combination,and the optimum ratio of soil improvement and Artemisia ordosica growth in 2016 and 2017 was 5%fly ash and 0.006%PAM combination.(5)Caragana microphylla,Hedysarum mongolicum and Elymus dahuricus were planted on artificial consolidated layer,the tolerance degree of plant height and ground diameter to artificial consolidated layer were respectively:Hedysarum mongolicum>Caragana microphylla>Elymus dahuricus,the negative inhibition effect of artificial consolidated layer on plant leaf were little,the order of leaf growth adaptability to artificial consolidation layer was as follows Elymus dahuricus>Caragana microphylla>Hedysarum mongolicum;the adaptability of plants biomass were ranked as Elymus dahuricus>Hedysarum mongolicum>Caragana microphylla.The optimal theoretical ratio of artificial consolidated layer was also suitable for growth and biomass growth of Caragana microphylla,Hedysarum mongolicum and Elymus dahuricus,and the results were of great value in desertification control engineering.