Spatial And Temporal Characteristics Of Soil Seed Banks In Ditch Systems Of The Sanjiang Plain

Germination method and vegetation investigation method were used to studycharacteristics of soil seed banks and aboveground vegetation in ditches of different yearsin the Sanjiang Plain. Characteristics of seed banks in multi-stage ditches system werestudied and compared with that of farmland and isolated wetland nearby. Spatial andtemporal characteristics of soil seed banks in ditch systems were discussed to exploresuccession characteristics of plant communities in ditches and their potential role inwetland biodiversity conservation.The results showed that the density of seed bank in ditches in the Sanjiang Plain washigh. Seed density of ditch banks was8973~25000seeds/m~2, higher than that of sedimentin ditches, which was506~1488seeds/m~2. A total of50species germinated belonging to20families,41genera. The number of species germinated from seed banks decreased withsuccession, the same as wetland plants.50species germinated belonging to16families,41genera were recorded in aboveground vegetation. Percentage of perennial species inaboveground vegetation gradually increased with succession. At the same time, Simpson,Shannon-Wiener indices and Pielou evenness increased, as species distribution tend to beuniform. Similarity index of seed bank and aboveground vegetation was low, which was32.7%~38.7%.Seed density of multi-stage ditches system was6784~15226seeds/m~2, higher than thatof isolated wetland. And there was no significant difference between multi-stage ditchessystem and10yrs farmland. In multi-stage ditches system, a total of39species germinatedbelonging to18families,33genera, and gramineae, cyperaceae and compositae plantswere dominant. Perennial species were in majority, accounting for59%. Wetland speciesaccounted for71.8%, and the number of wetland species was higher than that of farmland. Simpson, Shannon-Wiener indices and Pielou evenness decreased with the increase of ditchlevel. Species diversity was the lowest in farmland compared with multi-stage ditchessystem and farmland.According to this study, there were a large amount of wetland species in seed bankand aboveground vegetation in ditches, indicating that ditches play an important role inmaintaining plant diversity and have potential to be used in wetland restoration. Plantcommunity degradation with succession in ditches suggests that the function of ditches forbiodiversity conservation was limited for the long term. Management of ditches should bestrengthened.