| Wild Prunus divaricata Ldb.(or P. cerasifera Ehrh. or P.sogdiana Vass) is a kind of little arbor or sheepberry which belongs to Prunus. As an important species of the wild fruit forest in Ili river valley of Xinjiang, P. divaricata is a kind of National and Autonomous Region’s key protection species, and it plays important roles in regional ecosystem stability, conservation of water and soil, maintenance and conservation of biodiversity. And just as its phenotypic diversity, strong stress resistance and high nutritional value, wild P. divaricata has a good prospect of utilization and garden breeding. In recent years, with human acitivities’ expansion including deforestation, tourism development and overgrazing, the habitat’s fragmentation degree strengthened gradually, which has greatly strengthened the degree of endangerment and the stability of natural population of wild P. divaricata. In this paper, community species diversity and ecological forms, genetic diversity, population structure and regeneration traits, spatial and temporal patterns of seed rain and soil seed banks, seed predation, dispersal and burial by frugivores, the relationships between frugivores and seedlings’ establishment were studied to systematically explore the characteristics of wild P. divaricata population. And the main results were summed up as follows.1. The community was composed of 96 species which belong to 33 families, 78 genera in the wild P. divaricata forest. And the community had abundant ecological forms, including six growth form of plant, eight growth form of root, four Life form of Raunkiaer, four ecological type of water. In the growth form of plant, species belonged to limb type had the greatest proportion, endlong type took second place, and half bottom of lotus was the least. The growth form of root with tarproot had the largest number of community species; stolon form took the second place, earthnut, tuber and parasitic root ranked the least. Perennial species occupied the highest proportion of history life type, the second was biennial species, and the annual species which were composed of early spring ephemeral plant ranked the least. Geophyte species had the greatest proportion of life form, the second was therophyte form, and the hemicryptophyte species had the least proportion. The wild Prunus divaricata divaricata had the characteristics of growth and root form of herbage communities in the temperate grassland, and had the climatic characteristics of geophyte and hemicryptophyte plant in the temperate area.2. In the six studying habitats, plant height and crown structure of wild P. divaricata natural populations presented different structural characteristics and trends due to the differences of habitats. Population size structure was basically in stable. However, due to excessive interference, there was serious shortage of diameter class of populations in three habitats. The survival curve presented B1 type, which was step type, for the populations overally. Within each plaque, population structure was different, and showed strong volatility. There was a high recession risk of populations due to extreme lack of younger individuals.3. Among the fruit size parameters, fruit diameter, longitudinal diameter and fruit shape exhibited the highest variation in the red phenotypes, followed by the yellow phenotypes. The core length, width and nuclear shape in the red variants were also the highest. In the modules of the dried fruit, coefficient of variation of core and dry biomass were maximum in the four types, however, coefficient of variation of kernel dry biomass was maximized in purple variant. In SSR screening, all of the 14 loci showed high polymorphism except BPPCT004. The genetic diversity of wild P. divaricata was moderate(6.71 alleles per locus, H = 0.3295, I = 0.4899).4. The seed rain of wild P. divaricata ranged from mid-August to the mid/late December every year. There was certain time difference of seed rain among individuals of different phenotypes. The soil seed bank comprises integral vital seeds, integral non-vital seeds, broken seeds by rodents’ damage and rotted seeds. More than 80% of seeds were distributed in surface litter layer and in soil lighter than 2cm. The seed bank was a persistent type and seeds number performed a top-down vertical diminishing pattern. The wild P. divaricata seedlings contained five age classes in the four surveyed communities. The plant biomass accumulation of seedlings in one growth season was the highest in forest gap, followed by forest edge and understory. Seedlings in forest gaps had the highest root biomass and leaf biomass, but the lowest SLA. Among biomass allocation pattern, the root and leaf biomass allocation were highest for seedlings in the forest gaps. The asexual reproduction of wild P. divaricata existed a certain degree of selectivity. The seedling density and sprouting rate showed a pattern of steep slope > understory ground> valley bottom> gentle slope. The sprouting rate increased slowly at first and then a sharp decline according to basal diameter of maternal organism, and the percentage of distribution layer of adventitious buds from root suckers was maximum in the first layer(0~1 cm) in soil.5. Due to transportion and predation by rodents, there was no significant difference between P. divaricata seeds’ retention time. The rate of in situ feeding and disappearance of small seeds were significantly higher than big seeds and medium seeds. Although the avail(seed kernel weight / seed weight) of big seeds was minimum, rodents still preferred handling and storing more large seeds. The seeds of P. divaricata formed a short-term persistent soil seed bank, regardless of the animal disturbance. Litter retention could reduce animal’s handling and feeding, but not efficiently generated large numbers of newborn seedlings.The rodents’ transportion and feeding were the main factors affecting seeds’ fate and dynamics of seed banks. In the basin sowing conditions, seed germination and survival rate of seedlings reduced at different level after removal of the cotyledon. Plant height, basal diameter, root length, leaf number and leaf area per plant, and the plant’s total biomass, root, stem and leaf biomass and other growth parameters decreased with the increasing of cotyledon excision percentage. Thus, cotyledon had a very important role in seedlings survival, settlement and performance of wild P. divaricata.The results of this study will provide a comprehensive understanding of the population status, endangered form, rational development and utilization, and practical scientific methods to solve the population construction, distribution limitions and natural regeneration problems of wild cherry plum. Also, the present researches will provide theoretical guidance to develop techniques for preservation and sustainable use, and for the conservation and restoration of wild P. divaricata. |
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