| Soil seed bank is summation of vigor seed both in soil and on its surface, and which has important study value on population countermeasure and specie evolution. The study on the structure, composition and dynamic succession of the aboveground vegetation of soil seed bank will contributes a lot to the management of farmland, meadow, forest and natural reserve, and will be helpful to make right decision. In this study bourgeon method is adopted to observe the soil seed bank of Picea schrenkiana Fish.et Mey. forest in tianshan mountain from altitude 1800 to 2200 meters in two years, and niche, specie diversity and biology statistics are also used. The conclusion shows as follows:①There are mainly annual and perennial plants which is composed of Aegopodium alpestre Ldb., Trifolium repens L., Poa supina Schrad., Cicerbita azurea (Ldb.) Beauv. and Stellaria soongorica Roshev. in the species makeup of soil seed bank, and the P. schrenkiana Fish.et Mey. which is the dominant species can hardly reach to only 1%. It shows that 2004 is off year. As for the vertical distribution of soil seed bank , the amount of seed raises firstly, then decreases. The amount of seed reaches peak in 2~4cm and get 32.2%.②Age dynamic of soil seed bank is mainly showed in seed density and species diversity. The density of soil seed bank is 404.75±291.11ind/m2, and in 2005 is 635.75±478.97ind/m2. Except for two lines, all the others show an increase of the diversity of soil seed bank to certain extent. The dominant species in soil seed bank in 2005 is the same to 2004, but the proportions vary. And there is no change in specie composition.③After the niche study on dominant species in soil seed bank of P. schrenkiana Fish.et Mey.forest, the result shows that :The niche breadth of Draba nemorosa L. is the most wide in the soil seed bank, and Ranunculus pedatifidus Sm. the most narrow. The highest niche overlap is between Stellaria soongorica Roshev. and Cerastium bungeanum Vved., and the lowest between Plantago depressa Willd. and R. pedatifidus Sm.. The niche overlap is higher in the same class, and vice versa. To some extent niche can reflect relationship of different spieces.④The aboveground vegetation in the same plot is mainly composed of herb(98.527%), and its dominant species comprise A. alpestre Ldb.,C. azurea (Ledeb.) Beauv., Iris ruthenica Ker-Gawl.,Elymus nutans Griseb. and S. soongorica Roshev.. Arbor seeding occupies only 0.216%,shrub 0.212% and liane 1.046%. The similarity between soil seed bank and aboveground vegetation ranges from 0.2 to 0.286 totally. There is low similarity between soil seed bank and aboveground vegetation in fenced fields, but both of them get high diversity. The similarity between soil seed bank and aboveground vegetation in unfenced fields is little high than in fenced fields, because of less species. The index of specie diversity in the fenced field is much higher than in the grazing field, and which shows that the disturbance can increase the diversity of soil seed bank. The specie number of small sample in soil seed bank show a positive relationship with thickness of fog, root, humus and distance from matrix of Picea schrenkiana Fish.et Mey.⑤Through the seed disintegration experiment in nature, the results show that seed vitality of P. schrenkiana Fish.et Mey. decline from 74.5% to 37.58% in half a year, and to 6.09% one year later. The vitality shows a sharp decrease, and it is no difference to keep vitality in different soil layers.
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