Aims The response of herbaceous and woody plants to environmental stress is an important mechanism for the evolution of ecosystem structure and function in hydro-fluctuation belt of Three Gorges Reservoir. However, the pertinent response characteristics and whether there are group differences in these stress responses are still unclear.
Methods Here, we undertook a meta-analysis of the effects of typical environmental stresses (flooding and drought stress) on the physiological and ecological characteristics of suitable herbaceous and woody plants in the Three Gorges hydro-fluctuation belt, with an aim to reveal the response of suitable plant groups to flooding and drought stress from the perspective of species and life forms.
Important findings The results showed that: (1) Herbaceous plants and woody plants showed obvious growth and development inhibition and adaptive response in physiological and biochemical strategies under environmental stress, mainly manifested in the decrease of biomass and photosynthetic rate of each tissue and organ, the increase of malondialdehyde and proline content, and the initiation of antioxidant enzyme system (superoxide dismutase, peroxidase, catalase). (2) Flooding stress had the strongest negative effect on herbaceous plant biomass, followed by drought stress. Flooding stress had the greatest negative effect on total chlorophyll content and photosynthetic rate of woody plants, followed by drought stress, showing the life-form effect of environmental stress. However, the total chlorophyll content of herbaceous and woody plants was most sensitive to flooding stress, while woody plants showed a certain homeostasis to drought stress. The physiological and biochemical responses of woody plants to flooding stress were more significant than those of herbaceous plants, and the responses were mainly different from those of herbaceous plants in stomatal conductance, malondialdehyde and proline content, and peroxidase activity. The herbaceous plants showed stronger response to drought stress than did woody plants, and the response of total chlorophyll content, water use efficiency and antioxidant enzyme (superoxide dismutase, peroxidase, catalase) activity was different from that of woody plants. (3) The morphological responses of herbaceous and woody plants to different environmental stresses have tissue-specific differences. Herbaceous plants mainly adapt to flooding and drought stress by morphological changes of roots, stems and leaves, while woody plants mainly adapt via morphological changes of roots. In summary, this study presents an integrated view of the morphological and physiological characteristics of herbaceous and woody plants in response to environmental stress in the hydro-fluctuation belt of the Three Gorges Reservoir, which provided a scientific basis for evaluating the potential of different life-form vegetation in the ecological structure and functional restoration in this ecologically-important region.