The Characteristics of Soil Seed Banks under Different Restoration Patterns and Their Responses to Water-level Fluctuation in Fluctuating Belt of Xiangxi River
The construction of the Three Gorges Project increases flooding amplitude and alters flooding pattern of fluctuating belt,which is flooding in summer and emergence in winter before the project and now flooding in winter and emergence in summer in the reservoir area.This drastic change of water-level fluctuation has induced degradation of plants in the fluctuating belt.In order to evaluate the effects of restoration methods for soil seed bank and its response to the reverse seasonal water-level fluctuation in the fluctuating belt in Xiangxi River,the characteristics of soil seed bank,including composition,distribution,similarity with standing vegetation at the artificial and natural restoration sites were studied through field investigation of plants and soil seed bank,and germination experiment of seed bank samples.The results showed that restoration pattern had an influence on composition,biodiversity and distribution of soil seed bank.There were 44 species from 38 genera of 22 families in the soil seed bank at the artificial restoration site meanwhile 50 species from 42 genera of 19 families at the natural restoration site.The species biodiversity at the artificial restoration site was slightly lower than that at the natural restoration site.The highest species biodiversity occurred on the upper part and the middle part at the artificial restoration site and the natural restoration site,respectively.Under the influence of water-level fluctuation,the species composition and biodiversity were becoming simple at both restoration sites.The life form of soil seed bank was mainly composed of annual herbaceous species.Restoration pattern and water-level fluctuation also induced changes of soil seed bank in quantitative spatial distribution and its similarity with standing vegetation.The average seed density of soil seed bank at the natural restoration site reached 7 322.18 ind./m2 increasing 70.94％ in contrast to that at artificial restoration site.However,the quantitative spatial distribution of soil seed bank displayed pattern of the maximum occurred in the middle part of the fluctuating belt (altitude 165 m) at both sites.The similarity index between soil seed bank and standing vegetation increased because of water-level fluctuation at both sites as it reduced species diversity of soil seed bank and standing vegetation.There were 26 and 28 co-existing species between standing vegetation and soil seed bank at the artificial and natural restoration sites respectively.The similarity index at the artificial restoration site was slightly higher than that at the natural restoration site.It is concluded that present artificial restoration pattern with simple species diversity had limiting effects on the restoration of soil seed bank even it promoted the restoration of standing vegetation.
fluctuating beltsoil seed bankstanding vegetationwater-level fluctuationthe region of Three Gorges Reservoir
NETL
NSTL
万方数据
维普
