Spatial And Temporal Characteristics Of Picea Schrenkiana Forest Soil Seed Bank And Its Relationship With Aboveground Vegetation On The Northern Slope In The Central Part Of The Tianshan Mountains, Xinjiang

Picea schrenkiana forest is the zonal forest vegetation in Tianshan Mountains, and its ecosystemsustainability plays a crucial role in the sustainable development of Xinjiang oasis ecosystem. However,due to lacking in scientific understanding of the spatial and temporal characteristics of soil seed bank for along time, which performs important ecological functions in its regeneration and succession, it causes theconservation and sustainable management of P. schrenkiana forest ecosystem lacking for necessaryscientific basis. Therefore, based on those existing soil seed bank studies of P. schrenkiana forest, thispaper took P. schrenkiana forest soil seed bank on the northern slope in the central part of the TianshanMountains (at the altitude of1450-2750m) as the research object. The methods of abovegroundvegetation investigation, soil seed bank sampling and greenhouse natural germination were adopted in theresearch. Through the investigation of soil seed bank species composition, density, altitude distribution andits relationship with aboveground vegetation, the inter-annual variations of soil seed bank in P. schrenkianaforest, altitude distribution pattern and the species similarity with its aboveground vegetation werediscussed in this paper. The main results were as follows:97kinds of plants, attached to32families,69genera were germinated from10years soil seed banksampling from2004to2013. The woody plants were only P. schrenkiana, Betula tianschanica, Berberisheteropoda and Sorbus tianschanica. Species similarity of the soil seed bank was generally low amongdifferent years, whereas there were only6constant species in the10years. Czekanowski similaritycoefficients were between0.24and0.45. Species similarity of the soil seed bank turned out a trend ofdecreasing-increasing-leveling off with the interval years increasing.Both of P. schrenkiana forest soil seed bank density and the seed density of P. schrenkiana in the soilseed bank had extremely significant inter-annual variations, and there was no synchronization. Soil seedbank density of P. schrenkiana forest was between186.50±20.37seeds/m2and953.75±66.12seeds/m2,while the seed density of P. schrenkiana in the soil seed bank was between0.25±0.26seeds/m2and584.50±53.58seeds/m2, mainly affected by its seed harvests in the previous year.With altitude rising, both of P. schrenkiana forest soil seed bank density and the seed density of P.schrenkiana in the soil seed bank turned out an increasing-decreasing trend. The maximum value were atan altitude of1950-2050m and1750-2450m, so there was no synchronization. Czekanowski similaritycoefficients of species similarity in P. schrenkiana forest soil seed bank at different altitudes was not high,ranging from0.14to0.56. As the altitude rising, the number of sharing species at neighboring altitudesturned out a trend of increasing-decreasing-leveling off, but the species similarity showed a decreasingtrend. And so was it with altitude difference rising.Both of the species number in P. schrenkiana forest soil seed bank and aboveground vegetation turnedout a synchronous changing trend of increasing-decreasing. Generally speaking, the latter was more thanthe former. Species similarity between soil seed bank and aboveground vegetation was relatively low,whereas the average value of Jaccard similarity coefficient was only0.30. On the whole, the similarityturned out an increasing-decreasing trend with the altitude rising. The maximum was at about the altitudeof1800m, while the minimum was at about the altitude of2700m. Furthermore, the similarity coefficientin relatively low altitude areas was greater than that of the high altitude areas.