The Ecophysiological Responses Of An Invasive Plant Spartina Alterniflora To Durative Waterlogging Stress

Biological invasion, as an important part of the global change, has serious effects On biological diversity, ecosystem stability and service function. Since introduced to the Chongming Dongtan Nature Reserve in 1995, Spartina alterniflora has rapidly expanded and seriously threatened the biological diversity there. To control and eradicate the exotic and invasive plant Spartina alterniflora is important and necessary for biodiversity conservation management.Effects of waterlogging stress on physiological (soluble sugar, chlorophyll, MDA, SOD and POD) and growth responses (height, biomass, number of notes, et al.) of an invasive plant Spartina alterniflora and its adaptive mechanism under durative waterlogging condition were studied by the control experiment in 2007. The photosynthetic pigment responses of Spartina alterniflora and an indigenous plant Phragmites australis to durative waterlogging were investigated during the growing season of 2008 at Chongming Dongtan Nature Reserve. The results shwed:(1) The contents of soluble sugar and chlorophyll in leaves were lower than those of the control from the beginning of the experiment and then accumulated gradually. MDA increased remarkably at beginning and then decreased. The activities of SOD and POD increased at the beginning and decreased subsequently. Under the waterlogging condition, height, note length and biomass ratio of underground vs. aboveground were lower than those of the control.(2) The basic composition and contents of two species' pigments were diffirent and their responses to waterlogging were diffirent, too. Under durative waterlogging condition, the contents of Spartina alterniflora's chlorophyll a, chlorophyll b and carotenoid decreased and the values of chlorophyll a / chlorophyll b and carotenoid / chlorophyll increased. The pigment contents of Phragmites australis increased, the values of chlorophyll a / chlorophyll b and carotenoid / chlorophyll changed little under durative waterlogging condition. After relieving stress, the pigment contents of Spartina alterniflora increased, the values of chlorophyll a / chlorophyll b and carotenoid / chlorophyll decreased, near to the values of the controls, while the pigment contents of Phragmites australis were higher than the controls significantly. Two species showed the compensatory effect after relieving stress.(3) The results from this study indicated that durative waterlogging stress could inhibit the growth of Spartina alterniflora, while the plant could effectively adapted to the stress by physiological and morphological adjustment. Therefore, waterlogging together with other control measures should be an effective way for controlling the expanding of Spartina alterniflora. Phragmites australis could adapt to the stress better than Spartina alterniflora and should be used as a substituted plant during the recovery in wetland.