Soil seed bank and aboveground vegetation along a successional gradient on the shores of an oxbow.

摘要

The soil seed bank and aboveground vegetation were investigated on the shores of the Tian-e-zhou oxbow in China along a successional gradient (i.e. mud flat, sedge and graminoid marsh, sedge and reed meadow, and willow shrub). We expected to explore the following questions: (1) Does seed density and species richness of the soil seed banks decline during succession? (2) Does the similarity between the soil seed bank and aboveground vegetation decrease during succession? (3) Can soil seed banks be considered as a potential source of material for wetland restoration? Results revealed that 19 species (about 61% of the species in the mud flat stage) were found in all successional stages. Both seed density and species richness increased with succession. Species of the soil seed bank showed greater compositional similarity (Sorensen's index) across four stages than did the aboveground vegetation. The similarity between soil seed bank and aboveground vegetation increased as succession proceeds. In conclusion, the seed bank of Tian-e-zhou oxbow wetland contains a relatively abundant seed density and species richness. The soil seed bank could thus play an important role in the restoration management of oxbow wetlands. However, the high dominance of mudflat annuals and the absence of most dominant perennials in the soil seed bank suggest that target species may require active introduction for further restoration.