宜昌黄杨对夏季淹水的生理生态学响应

Ecophysiological responses of Buxus ichangensis to summer waterlogging

宜昌黄杨(Buxus ichangensis)主要分布于长江三峡地区的消落带,对该地区的水土保持和岸坡地稳定起着十分重要的作用。作者通过模拟夏季淹水研究了宜昌黄杨的形态特征、光合作用和根系活力的变化特征,揭示了宜昌黄杨对淹水的生态学响应规律。结果表明宜昌黄杨在淹水过程中产生了皮孔、不定根等形态适应特征,经过60d的淹水处理,植株仍全部存活,表现出较强的适应能力。但是植株的生长仍然受到淹水的显著影响:淹水条件下宜昌黄杨的最大光合速率、气孔导度和根系活力与对照相比都显著下降,60d后分别只有对照的19.24%、24.04%和4.78%。在不同处理阶段这些指标下降的幅度不同:初期的下降幅度最大,后期下降幅度减少,其中根系活力在后期还有所回升。叶绿素A的含量随淹水延长持续下降,后期有所回升,而叶绿素B和类胡萝卜素的变化却不大。最后,作者对该物种在水电工程库区退化消落带植被生态恢复中的应用提出了一些建议。

As a widely distributed shrub species on the hydro-fluctuation belt in the Three Gorges Area,Buxus ichangensis is of vital importance for conservation of soil and water,and recovery of vegetation in this area. To determine its tolerance to flooding,we performed simulated waterlogging on this plant and then examined its responses in photosynthesis,roots activity and pigment contents. Our experiment showed,all the B. ichangensis plants could survive after 60-day inundation treatment,partly because of morphological adaptation triggered by the waterlogging,such as development of lenticels and adventitious roots. However,the variables of net photosynthesis rate,stomatal conductance and root activity reduced to 19.24%,24.04% and 4.78% of the control,respectively,and the decreasing amplitude varied in different flood periods,significantly decreasing primarily and resumed a little at the end of experiment. Chlorophyll A content significantly decreased along with waterlogging time,whereas chlorophyll B and carotenoid contents presented indistinctive changes after different waterlogged durations. Based on these,we concluded that B. ichangensis had strong tolerance to summer flooding. We provided some suggestions on how to utilize the species in the restoration of degraded riparian vegetation in reservoir area of hydroelectric project.