The Soil Seed Bank And Relationship With The Aboveground Vegetation In The Degradation Areas Of The Napahai Reserve Of Plateau Wetlands In Northwest Yunnan

The soil seed bank is a potential component of the aboveground vegetations, and the major resource of vegetation restoration after disturbance. It plays a significant role in restoration and reconstruction of degraded ecosystem. The vegetation of Napahai reserve in northwest Yunnan has been degraded by two modes, mode 1-pigs and other large livestock stocking strongly degraded areas with heavy interference to soil(There are five representative communities),mode 2-Abandoned land which has poisonous weeds such as Euphorbia jolkinii and Stellera chamaejasma(There is a representative community). We through investigate the size of seed bank, species composition, and relationship of seed bank and aboveground vegetation, attempting to find the distribution pattern of seed bank in these areas, the role of seed bank in the process of plant communities construction. Moreover, this study provides a theoretical basis for restoration and reconstruction of degraded ecosystem in plateau wetlands The result showed:1) There rich seed bank resources exist in the degradation areas of Napahai reserve. The mean viable seed density of degraded communities was 880 Ind.m-2 to 35600 Ind.m-2. And the mean viable seed density of compared communities was 960 Ind.m-2to48160 Ind.m-2.2) To 6 compared communities and EJ, PA community, the vertical differentiation of mean seed density was significant, which appeared the number of seeds decreased from upper layer of soil to middle and lower. The mean seed density of SSB(soil seed bank) collected in Nov. was higher than Jun. And the mean seed density of SSB from moist germination was higher than waterlogged germination. On the contrary, to the other 4 degraded communities, all the differentiation of seed density was not exist. The mode 1 of degenerated form has significantly reduced the variation of seed density at vertical differentiation, seasonal differencing and water treatment differences.3) The families of taxon of SSB were similar between degraded and compared communities. The annuals have more contribution to the total number of SSB when the perennial was 60%, while the annual was 40%. Cyperaceae, Ranunculaceae, Compositae, Scrophulariaceae, Poacea, Rosaceae were the common dominant families in the degraded and compared communities of SSB. The 4 kinds of species diversity index had not the difference between degraded and compared communities of SSB. To the Shannon-Wiener index, Pielou index and Simpson index, EJ has the highest value, while CPH has the lowest. The Jaccard index between degraded and compared communities around 0.36 to 0.57.4) The families of taxon of the aboveground vegetation were higher than SSB. The perennial was 70%, while the annual was 30% in the aboveground vegetation. The common dominant families of vegetations had more one family than SSB. That was Polygonaceae. The mode 1 of degenerated form has significantly reduced the value of species richness and value of Shannon-Wiener index in the aboveground vegetations, with no influence to the Pielou index and Simpson index of vegetations. Submerged condition of wetland decreased diversity of aboveground vegetations particularlly to CPA.5) The result of NMDS indicated that the similarity of SSB and vegetation was low, and the similarity within SSB was high than the similarity within vegetation. The heavy disturbance plots had the most similarity. In general speaking, the contribution of seed bank to aboveground vegetation community was not big.