比较研究了模拟干旱及自然水分梯度条件下蒙古柞树种光合生理指标 ,模拟干旱处理试验土壤含水量分别控制在田间持水量的 85 %～ 10 0 % (CK)、6 5 %～ 85 % (MW )和 4 5 %～ 6 5 % (LW ) .结果表明 ,干旱胁迫对蒙古柞幼树净光合速率、气孔导度、蒸腾速率、水分利用率、表观CO2 利用率和表观光能利用率等生理指标均产生明显影响 .野外自然条件下水分梯度对蒙古柞大树气孔导度、水分利用率和净光合速率有显著影响 ,但对蒸腾速率、表观CO2 利用率和表观光能利用率的影响不显著 ,中等水分条件可明显提高蒙古柞大树叶片的气体交换和水分利用率 ,说明蒙古柞树种叶片气体交换和表观资源利用率对干旱胁迫的响应程度不同 .蒙古柞树种是干旱可变植物 ,长期水分胁迫可提高树种的耐旱能力 ,特别是中等水分胁迫能保持蒙古柞固有的强劲耐旱能力 The photosynthetic physiological indices of Castanopsis oak were studied comparatively under simulated and natural water gradients. Soil moisture under simulated drought treatment was controlled at 85% ~ 100% (CK), 65% ~ 85% (MW) ) And 45% ~ 65% (LW) respectively.The results showed that under drought stress, the net photosynthetic rate, stomatal conductance, transpiration rate, water use efficiency, apparent CO2 utilization rate and apparent light energy utilization rate Physiological indexes had significant effects on the stomatal conductance, water use efficiency and net photosynthetic rate of the tree species, but the effects of transpiration rate, apparent CO2 utilization rate and apparent light energy utilization rate But the effect was insignificant. The moderate water condition could obviously improve the gas exchange and water use efficiency of the leaves of Mongolian oak tree, indicating that the leaf gas exchange rate and apparent resource utilization rate of Mongolian oak tree species had different responses to drought stress. Change of plants, long-term water stress can increase the drought tolerance of species, especially moderate water stress can maintain the inherent strong drought tolerance of Mongolia oak