| Dynamic changes of soil moisture of different vegetation in sandy land of zhang gu tai by position-monitoring. The eight different vegetations are:grass land, scots pine plantation,chinese pine plantation,poplar plantation,scot pine-poplar mixed plantation,elm forest, prunus armeniaca forest and abandoned farmland.The results shows that diversity index of cot pine-poplar mixed plantation is the highest and it is the lowest in abandoned farmland.The vegetation community under the scot pine-poplar mixed plantation is the most stable. The organic matter content is the highest in abandoned farmland.The rainfall amount and the vegetation growing all cause the changes in soil moisture content.The soil moisture of eight vegetation types all decrease and then increase in April,but in May the soil moisture all increase at first except for elm forest and prunus armeniaca forest.The evapotranspiration of scots pine plantation is 433.27mm, evapotranspiration of grassland is 460.39mm,evapotranspiration of chinese pine plantation is 364.25mm,evapotranspiration of poplar plantation is 414.33mm,evapotranspiration of prunus armeniaca forest is 516.09mm, evapotranspiration of scot pine-poplar mixed plantation is 495.79mm, evapotranspiration of elm forest is 381.34mm, soil water deficit in prunus armeniaca forest and scot pine-poplar mixed plantation.The prunus armeniaca forest has a big density which causes big evapotranspiration. Thinning or pouring should be adopted to reduse soil dry layer phenomenon. The evapotranspiration is smaller than rain fall in scots pine plantation and chinese pine plantation. Periodic monitoring should be performed on the pine plantation,because the poplar plantation is in young plantation. |
