Responses of Swamp Cypress (Taxodium distichum) and Chinese Willow (Salix matsudana) Roots to Periodic Submergence in Mega-Reservoir: Changes in Organic Acid Concentration

Organic acids are critical as secondary metabolites for plant adaption in a stressful situation. Oxalic acid, tartaric and malic acid can improve tolerance under waterlogged conditions. Two prominent woody species (Taxodium distichum-Swamp cypress Salix matsudana-Chinese willow) have been experiencing long-term winter submergence summer drought the Three Gorges Reservoir. The objectives of present study were to explore responses roots two during flooding reflected by root tissue concentrations organic acids. Potted sample plants randomly divided into three treatment groups: control, moderate submergence, deep submergence. oxalic main lateral determined at four stages. results showed that T. distichum S. matsudana adapted well water regimes reservoir, with survival rate 100% experiment period. After cycle emergence, height base diameter increasing trends. Changes insignificant differences between treatments, only was significant influenced emergence spring, could adjust their metabolisms normal level. Among acids, most sensitive response which deserved more studies future. exotic species, distichum, had stable metabolism flooding. However, native matsudana, responded actively Both be considered vegetation restoration, but it needs observations planting around 165 m above sea level, where is than 200 days.