塔克拉玛干沙漠高矿化度水灌溉苗木地下生物量研究

Underground Biomasses of Nursery Grown Plants Irrigatedwith Highly Mineralized Water in Taklimakan Desert

2003年在塔克拉玛干沙漠腹地肖塘地区进行了高矿化度水(28g/L)滴灌造林试验。秋季用根系挖掘法研究了定植当年的梭梭、柽柳和盐穗木的地下生物量,研究结果表明:(1)定植当年苗木地下生物量主要分布在表层20cm,向下逐渐减小,生物量的分布与深度呈显著的负指数关系。(2)不同样地间比较发现苗木根系生长遵循限制因子定律:在灌溉水质、灌水定额、施肥量、施肥时间等人为影响因子一致时,土壤类型、土壤结构、坡向和坡位等自然因子中差异最大的因子是苗木根系生物量累积的限制因子,它们分别通过改变土壤的紧实度和水分状况、地表太阳辐射强度和与风速有关的地表蚀积状况和壤中流向影响土壤含水率来影响苗木的生长。(3)树种间根系生长和分布也显著不同,根系分布深度和生物量表现为梭梭>柽柳,在丘间粘土质土壤中盐穗木>柽柳。

An experiment was carried out to exploit drip irrigation with highly-mineralized water (28 g/L) for afforestation in the Xiaotang prefecture located on the northern boundary region of Taklimakan Desert in 2003.Root digging was adopted to study the underground biomasses of Haloxylon ammodendron,Tamarix hispida,and Halostashys caspica in the winter of the year when they were permanently planted,which concluded that (1) their underground biomasses mainly distributed and declied with increased depth in 0~20 cm soil in the year when they were permanently planted,which showed the biomasses had a significant negative exponential relation whith soil depth;(2) the comparison of the roots in different sampled plots showed that the root growths of these plants still followed the limiting factor law,that is to say,when such human factors such as irrigation water quality,irrigation quota,and fertilization rates and times remained consistent,those of such naturalfactors such as soil types and structures,and slope aspects and positions that differed most were the limiting factor to the biomass accumulations of the plants,which affected nursery grown plants through changing soil compactness and moisture,solar radiation on soil sufrace erosion relating with wind velocity,and soil movement;(3) different tree species significantly differed in root growth and distribution,and their root distributions and underground biomasses showed the pattern of Haloxylon ammodendron>Tamarix hispida as well as Halostashys caspica>Tamarix hispida with caly siol.