河西地区碱茅属植物草地水盐动态的研究

Studies on Soil,Water and Salt Dynamics of Puccinellia Grassland in Hexi Region of Western Ganus

本文研究了河西地区２年生、３年生、４年生碱茅属植物人工草地及撩荒地的水盐动态。试验结果表明：１）土壤水分含量从表层到底层（０～１００ｃｍ）呈梯度形分布。上述四类草地分别分布在２１．６％～４４．２％、２５．９％～４４．０％、３５．０～４６．２％、３５．５％～４６．４％之间，在定期灌溉条件下，各草地２０ｃｍ以下土壤水分含量在相同层之间差异不显著。２）土壤表层（０～１０ｃｍ）盐分含量较高，１０ｃｍ以下盐分含量急剧下降。表层盐分含量以撩荒地最高，４年生、２年生及３年生碱茅草地分别次之，平均值依次为２．４６％、１．２１％、０．２３％、０．１８％。２０ｃｍ以下各层土壤盐分含量各草地均很小，不同草地的同一层及同一草地的不同层之间差异不显著。各草地在５月与９月有两个返盐期，其它各月（６月、７月、８月）盐分变化较平稳。３）土壤盐分含量与地下植物量无显著相关性，地上植物量的增大，使得草地以蒸腾为主的土壤水分散失量也大幅度增大，这揭示了碱茅草地治盐作用的内在机理。

In the paper,The soil,water and salt dynamics of Puccinellia grassland and its wasteland used in checkobservation for the succesive two,three and three years,groewths were studied.The results obtained wereindicated as follows:1.The soil water contents from top to the bottom layer(0～10 0cm)were appeared to have a gradientdistribution,and under the constant situation of irrigation,those under the 20cm layer showed nosignificant differences among the same layers in horlzontal distribution in some different locations ofPuccinellia grassland and check wasteland during our experimentation。2. The soil salt contents of Puccinellia grassland and its check wasteland on the surface layer(0～10cm) werecomparatively higher , whereas those under the 10cm layer would decline fast rather soon,In comparisonwith the Puccinellia grassland,the soil salt contents on surface layer of the wasteland were ranged from thehighest,and then to the second places on Puccinellia grassland at the four-,two-and three-years’growth stages of the grass sp. on trial by successive order,the respective mean values were recorded as inthe following:2.46 (check),1.21,0.23 and 0.18%,The soil salt contents indicated Similarly in lowergradiency under the 20cm layer and all of them showed no siginificant differences from the same lavers ateach growth stage on the two treated lands。3.The salt contents showed not and relationship with the underground phytomass growths ,and quite thereverse,had an intimate relationship with the aboveground,and furthermore,the increasing amount ofwater evaporation(mainly,consists of respiration)still increased fast with the increasing scale ofaboveground phytomass。This fact herewith revealed the mechanism that why Puccinellia grassland can be insuch a wav so as to reduce the soil salt contents。