Studies On Population Structure And Regeneration Of Malus Sieversii In Emin County

Malus sieversii（Ledeb.）Roem.,as the world apple gene bank,is a rare and endangered tree species in China,and belongs to the national second-class key protected wild plants.Through the combination of the investigation method and the seedling renewal technology,the population structure and spatial distribution of soil seed bank were investigated to understand the living conditions,and further explore the suitable seedling regeneration contents of M.sieversii in Emin County.The purpose is to reveal population status of M.sieversii in Emin County,which provides the certain theoretical foundation for the population status renewal and rejuvenation of M.sieversii.The results are as follows:（1）M.sieversii were declining population,and there were few young individuals in the population.NoⅠandⅡage class individuals were found in shady slope,sunny slope and valley bottom,and the proportion of middle age class M.sieversii was the largest.In the shady slope,VI and X age classes are the dominant age classes,accounting for 56%;in the sunny slope,VI and VII age classes are the dominant age classes,accounting for 55.13%;at the bottom of the valley,there are no individuals ofⅢand X age classes,andⅤand VI age classes are the dominant age classes,accounting for 61.12%.Among the three habitats,the number of M.sieversii.was in the order of valley floor>sunny slope>shady slope.（2）The average total density of soil seed bank of M.sieversii was 10.20 seeds·m^-2.Seeds with different retention conditions in soil showed significant differences,which were rotten seeds>empty seeds>intact seeds.There was no significant difference in seed reserves of M.sieversii different habitats,which was sunny slope>shady slope>valley floor.In vertical space,the number of seeds decreased gradually with the increase of soil depth,and the number of seeds in litter layer was>0-2 cm soil layer>2-4 cm soil layer.The density of soil seed bank in vertical direction had little change in different habitats.The number of young individuals was negatively correlated with the distance from mother plant,and the number of young individuals decreased with the increase of the distance from mother plant.In the three habitats,the number of seedlings in the range of 0-1 m and 3-4 m from the mother plant:sunny slope>shady slope>valley floor;Within the range of 1-2 m and 2-3 m from the mother plant:shady slope>sunny slope>valley floor;Within 4-5 m from the mother plant:shady slope=sunny slope>valley floor.During the growth of young individuals from seedlings to short sapling and tall sapling,the proportion of seedlings in three habitats decreased,while the proportion of root tiller seedlings increased gradually.The number of root tiller seedlings of M.sieversii was much larger than that of seedlings.The proportion of root tiller seedlings accounted for 91.23%of all young individuals,while the proportion of seedling was only 8.77%.（3）The planting seedlings for afforestation technology of M.sieversii was studied,and different treatment methods were selected for field planting seedlings for afforestation experiments（Soil preparation,plastic film mulching and planting mode）,and the most suitable technology of M.sieversii population without artificial water supply was explored.The results showed that the most suitable technology for M.sieversii population was as follows in three process modes:planting seedlings per plant on the basis of land preparation in fish scale pit,and covering litter to preserve soil moisture.