Comparison Studies on Dew Condensation of Different Developmental Artificial Crusts in Hopq Desert

Dew is one of important environmental factors for desert ecological system in semiarid and arid regions.In this study,the artificial crusts were selected for experimental objects to compare differences of dew condensation amounts between different artificial crusts by means of daily detection for dew condensation on artificial crust surfaces.Concerning the experiment,artificial cyanobacterial crusts(ACC),artificial algal crusts(AAC),artificial moss crusts(AMC),and natural moss crusts(NMC) as well as shifting sands(SS) were selected as experimental materials,respectively.The experiment period was 42 days.Moreover,the cloth-plate method(CPM) was used for comparing dew condensation effects among the crusts.Results showed that the average daily dew amount as measured by CPM was 0.02~0.35 mm and the dew amount of ACC was 0.012~0.191 mm.the other dew amounts were 0.032~0.230 mm,0.048~0.274 mm,and 0.056~0.304 mm as well as 0.003~0.083 mm occurring on AAC,AMC,NMC and SS,respectively.It was found that there were obvious differences following developmental extents of artificial crusts,and the order of dew amounts in artificial crusts was as follows: NMCAMCAACACCSS.In addition,it was indicated that the formation and development of artificial crusts could accelerate dew deposition and dew assimilation,and the crusts could condense and retain more dew than sand.At the same time,there was more slow drying process of dew from the crusts than that from sand.The reason that the artificial crusts could condense abundant dew may depend on rich algal filaments,extracellular polymers and microclimatic characteristics as well as soil properties within the crusts.It might be necessary for us to fully understanding the mechanisms of dew condensation and assimilation on surfaces of the artificial crusts,and to further disclose the important ecological sense of dew in survival of the crusts.Furthermore,the research verified that the artificial crusts had good soil and water conservation functions,and also provided some experimental and theoretical bases for soundly evaluate the crust's potential application in fighting desertification by means of using non-rainfall water sources from dew.