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以长白山针阔叶混交林优势树种蒙古栎为实验对象,研究了生长季(6—9月)减少降水30%(人工截留穿透雨30%)对蒙古栎叶光饱和光合速率、气孔导度、蒸腾速率和水分利用效率的影响。结果表明:在叶片生长初期(6月),减少降水使土壤含水量降低26.4%,减少降水条件下与对照条件下叶片的光饱和光合速率无明显差异,但明显下降的蒸腾作用使蒙古栎叶片的水分利用效率增加了40.3%;7—9月,较高的自然降水量导致不同降水处理条件下的土壤含水量无显著差异,因而叶片的光饱和光合速率、气孔导度、蒸腾速率和水分利用效率亦无明显影响;由此可见,无论是低雨量时期(6月)还是高雨量时期(7—9月),长白山地区降水减少30%不会影响成熟蒙古栎的光合能力;8月的高光合速率可能说明,较高的土壤高含水量并未形成对蒙古栎根系吸水的限制。研究结果认为,成熟蒙古栎能适应较广的土壤含水量范围,在未来气候变暖、降水量变化条件下仍能保持较强的生长和适应能力。
Taking Quercus mongolica, the dominant tree species in the coniferous and broad-leaved mixed forest of Changbai Mountain, as experimental object, the effects of 30% reduction in precipitation (June-September) on the light-saturated photosynthetic rate and stomatal conductance , Transpiration rate and water use efficiency. The results showed that in the early stage of leaf growth (June), reducing precipitation decreased soil water content by 26.4%, and there was no significant difference in light - saturated photosynthetic rate of leaf under the condition of precipitation and precipitation. However, Of water use efficiency increased by 40.3%. From July to September, the higher natural precipitation led to no significant difference in soil water content under different precipitation conditions. Therefore, the light-saturated photosynthetic rate, stomatal conductance, transpiration rate and water content Therefore, it is obvious that a 30% reduction of precipitation in Changbai Mountain will not affect the photosynthetic capacity of mature Quercus mongolica in both the low rainfall period (June) and the high rainfall period (July-September) The high photosynthetic rate may indicate that the higher soil water content does not limit the water uptake of Quercus mongolica roots. The results show that mature Quercus mongolica can adapt to a wide range of soil moisture content, in the future climate warming, precipitation conditions can still maintain a strong growth and adaptability.