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采用中子水分探测仪、光电叶面积仪和 LI- 1 60 0型稳态气孔计对羊草草原的水分利用进行野外实验观测。结果表明 ,羊草种群蒸腾速率 T( t)的季节变化主要取决于 2 0～ 40 cm土层贮水量 ( SW4 6 ) ,光合有效辐射 ( FAR)和大气日均温 ( AT)的影响 ,其中 2 0～ 40 cm土层贮水量对羊草蒸腾速率的季节变化影响最大。羊草蒸腾耗水量的季节动态归根结底受控于大气降水的时空分布 ,并在时间上滞后于大气降水一旬左右。羊草的水分利用率 ,主要受植物生长大周期的控制。生物量在前期积累较快 ,相应的水分利用率高 ,而后期增长缓慢 ,水分利用率低
Field experiments were conducted on the water use of Leymus chinensis grassland using neutron moisture detector, photoelectric leaf area meter and LI-1 60 0 steady-state stomatometer. The results showed that the seasonal variation of transpiration rate T (t) of Leymus chinensis population mainly depends on the water storage capacity (SW4 6), photosynthetically active radiation (FAR) and daily average air temperature (AT) at 20-40 cm soil depth The water storage capacity of 0 ~ 40 cm soil layer had the greatest effect on the seasonal variation of transpiration rate of Leymus chinensis. The seasonal dynamics of transpiration water consumption of Leymus chinensis is ultimately controlled by the temporal and spatial distribution of atmospheric precipitation and lags behind by about ten days of atmospheric precipitation in time. Leymus chinensis water use efficiency, mainly controlled by the plant growth cycle. The accumulation of biomass in the early stage is faster, the corresponding water use efficiency is high, and the late growth is slow, the water use efficiency is low