The ecophysiological response of three shrub species to flooding

It is important to understand the ecophysiological adaptation of plants to flooding stress for selecting pioneer species to restore riparian vegetation. Three shrub species distributing in the Three Gorges Reservoir area, including Myricaria laxiflora, Salix variegata and Buxus ichangensis, were studied by simulating flooding, and their ecophysiological responses were uncovered. The results showed that M. laxiflora had the strongest adaptation to flooding, S. variegata and B. ichangensis ranked the second and the third respectively. Short time flooding resulted in continue decline of physiological activity in photosynthesis and transpiration. However, physiological activity of plants would gradually become stable and maintain at a certain level to keep their life. Flooding also caused the decrease of leaf chlorophyll and carotenoid contents, but the chlorophyll a/b ratio rises to improve the photosynthetic efficiency. The three shrub species also changed in morphological characteristics and life history to adapt flooding in an integrated mechanism. M. laxiflora became rest during flooding season meanwhile S. variegata and B. ichangensis developed adventitious roots to increase oxygen supply.