Soil Seed Bank In Tian-E-Zhou Oxbow Degraded Wetland:Community Characteristics And Regeneration Under Different Water Conditions

Soil seed bank has been an important foundation to restoration of degradation wetland plant communities. This study focus on a wetland degradation zone, which is in Tian-E-Zhou elk Nature Reserve, Shishou, Hubei province. The relationship between seed bank and aboveground vegetation was studied by a seedling germination experiment and a field investigation, while the species composition of soil seed bank, photosynthetic characteristics of dominant species, difference of growth index in different water gradient was explored by a controlled experiment.The results showed that the seed bank was composed of 18 families,33 genera and 34 species (dominated by 23 annual species), average seed density in the seed bank was 6,153 seeds/m2. While the aboveground vegetation comprised of 21 families,32 genera and 32 species (including 21 perennials). The species composition of the soil seed bank and aboveground vegetation was similar, but aboveground vegetation species diversity and evenness were higher than in the seed bank. The predominant species in the seed bank were Setaria viridis and Poa annua. Conversely, dominant species in aboveground vegetation were Cayratia japonica, Paederia scandens and Sambucus javanica. In controlled experiment, there were 23 species belongs to 13 families and 22 genera, the dominant species was Setaria viridis; the net photosynthetic rate (Pn), transpiration rate (Trmmol) and stomatal conduction (Cond) of dominant species showed a trend of first increasing and then decreasing with the water gradient, and the changes had a significant threshold response; in leaf index, except for leaf width, leaf number of single plant, leaf thickness, leaf length and leaf area were not significantly different in different water gradient; in other growth indicators, species in single pot, plant height, inflorescence number, node number, stem diameter, root dry weight and root shoot ratio in different water gradient significant difference.This study preliminarily reveals the connect between the seed bank and aboveground vegetation in the degraded wetland zone of Tian-E-Zhou, the plant growth indexes of the same soil seed bank were significantly different under different water gradient, which could be used as theoretical guideline and scientific background for the restoration in the degraded region.