Survival, Growth and Biomass Allocationin Seedlings of Common ash (Fraxinus excelsior L.)as affected by flooding Stress

The aim of this study is investigation of survival، vegetative characteristics and biomass allocation in seedlings of common ash (Fraxinus excelsior L.) grown in different water regimes. For this purpose، seedlings of ash were examined in a completely randomized design for 120 days in an open area of bottomland forest at two levels of soil moisture regimes (permanent flooding، periodic flooding with a rotation period of 15 days) and control level. At the end of the experiment، flooding decreased survival، vegetative characteristics، biomass allocation and vitality of ash seedlings. This reduction in permanent flooding was more than at the periodic flooding. In contrast، diameter growth response in periodic flooding was greater than permanent flooding and control level. The reason of this phenomenon can be attributed to the development of woody xylem cells. In periodic flooding، compared to permanent flooding، because of greater production of adventitious root and soil drainage، access of oxygen required for metabolism was easier and Photosynthetic organs of the plant (leaf area) and leaf biomass prominently increased. Overall، the results showed that F. excelsior was tolerant to flooding and can be used for restoration of bottomland forest، riparian area، lagoons and plains exposure to periodic flooding.