鄂尔多斯高原沙柳幼苗对模拟降水量变化的响应

摘要

Ordas plateau is a typical dry and semi-dry sandland in China.The distribution pattern and productivity of terrestrial ecosystem are greatly affected by the global change,especially the global precipitation change.Response is investigated for seedlings of Salix psammophila,a dominant shrub in Ordas plateau,to the global precipitation change by artificially controlling water supply at four levels.The results show that photosynthetic rate,transpiration rate,stomatal conductance and fluorescence efficiency increased as water supply increased,and water use efficiency was not affected by water supply.The growth changes of tree height,branch number,leaf number and leaf area had obviously difference among the four water supply treatments.The growth characters,such as tree height,stem diameter,leaf number,leaf area,dry biomass and value of shoot/root dry biomass,and bifurcation characters,such as bifurcatin ratio,branch number,length,leaf number,leaf area of each order,increased when water supply increased.%鄂尔多斯高原是中国干旱、半干旱沙区典型沙地。随着未来全球变化，尤其降水变化进一步激烈，将给这里的陆地生态系统分布格局和生产力带来巨大影响。选择鄂尔多斯高原优势灌木沙柳为研究对象，人为控制4种供水量水平来探讨沙柳幼苗对模拟降水量变化的响应。结果表明，幼苗净光合速率、蒸腾速率、气孔导度和荧光效率随着供水的增加而增大，而供水对幼苗的水分利用效率影响不显著；不同供水量的沙柳幼苗树高、枝条数、叶数和叶面积生长动态存在明显差异，随着供水量的增加，沙柳幼苗树高、基径、枝条数、叶数、叶面积、生物量干重和冠根生物量干重比值均逐渐增大；供水显著增加了沙柳幼苗总分枝率、各级枝条数、枝条长度和叶面积。