Response of Taxodium distichum to winter submergence in the water-level-fluctuating zone of the Three Gorges Reservoir region

Abstract

This study investigated the physiological and ecological processes of Taxodium distichum in the water-level-fluctuating zone (WLFZ) of the Three Gorges Reservoir (TGR). We determined the contents of non-structural carbohydrates (NSCs), N and P in the aboveground parts and root systems of T. distichum individuals that had experienced 3 yearly flooding cycles. These flooding cycles were driven by the operation of the reservoir in the Zhong County vegetation restoration demonstration area. This flooding inhibited the growth of T. distichum. The plant heights and canopy diameters of the flooded groups were significantly smaller than those of the control group. The flooding facilitated the synthesis of NSCs, and the soluble sugar content in the NSCs increased. The flooding inhibited the uptake of N and P, but the N/P ratios remained stable. The ratios of NSCs to N or P increased. T. distichum adapts well to submergence because of its regulation of NSC synthesis and storage, its balancing of the inputs of photosynthetic products to growth and storage, and its storage of material during exposure to maintain physiological activities during winter submergence and the energy sources required for growth during exposure. This study may provide a useful reference for use in vegetation reconstructions in areas with hydrological characteristics similar to those of the TGR.

Keywords

• flood tolerance
• taxodium distichum
• three gorges reservoir
• vegetation reconstruction
• winter submergence