The Population Dynamics And Reproductive Ecology Of Quercus Wutaishanica In Loess Plateau

Quercus wutaishanica is the constructive species of zonal vegetation in Loess Plateau,its population restoration is very signality to local vegetation construction.Based on the sample plot survey,documents and specimens,summarized the geographic distribution and the biological and ecological characteristics,studied the mutual adaptation characteristics of the population structure from the North Qinling Mountain Slope to Huanglong Mountain until Qiaobei,the sexual reproduction and the asexual propagation as well as the relationship between them and the environment factor;Puts forward suggestions of the population rejuvenation and the natural forest protection management.The main results were as following:(1) The distribution involving eighteen provinces in North China,Northeast China, Northwest China.In North China,existing a large area of pure forest.It grows the best on Qinling Mountain,so Qinling Mountain may be the distribution center.Vertical distributed from 300m to 2700m.On the whole,the distribution upline in the west is higher than the east and the south is higher than the north.The seed setting amount is high and the sexual reproduction plays the main role in the reproduction while the asexual propagation plays only a subsidiary role.Population fluctuation is affected strongly by environment factor.The stage from seed to seedling establishment is the most fragile part in its whole life history.After germination,root system grows preferentially and the aerial part grows lag behind.The fast-growing period of height is 10-40,diameter is 20-60.The fast-growing period of individual growth in Qinling Mountain is longer than the Loess Plateau.(2) The population structure from the North Qinling Mountain Slope to Loess Plateau (Huanglong,Qiaobei) shows progressive type,and the static life table shows that the mortality rate of annual to three-year-old individuals is high.The survival curve shows Deeveyâ…¢.With the increasement of diameter class,the mortality rate shows the trend of "high-low-high".Both the density and the mortality rate of the juvenile period in Loess Plateau are higher than Qinling Mountain,but the adult individuals grow stronger in Qinling Mountain.This suggests that Quercus wutaishanica forms the style of higher seed setting but higher mortality rate to maintain population' stable development when faces the rigid environment in Loess Plateau.So,the existing population will restore in a short time under great conservation and proper tending measures.(3) The point-survey in Huanglong and Qiaobei shows that the sexual reproduction of Quercus wutaishanica is well developed.The seed setting is affected by slope direction.The seed quantity of per plant in north slope is the smallest and the residual three are all large.The quantity of one year old seedlings is also the smallest in the north slope,so as the ratio of one year old seedlings and seeds.Every stage,including the flowering and fruiting,the seed fallout and seedling establishment,is affected by environment factor.The main loss of seed is transporting and feeding activity by animals.Light is beneficial to flowering and fruiting and organism content of soil,thickness of soil,air temperature,air humidity,water content of soil are beneficial to germination.(4) The asexual propagation of Quercus wutaishanica exists as three styles:sprouts germinating from stump,sprouts germinating from main root and sprouts germinating from root system.In comparison of different habitats,the density of the sprouts germinating from stump is the highest,the sprouts germinating from main root is the next and the sprouts germinating from root system is the final one.Both the average height and the average basal diameter of the three types are the highest in south slope and the lowest in north slope.The contribution ratio of sprouts is higher than seedlings,also the growth situation.The selection of reproductive function is closely affected by jamming intensity.With the reducing of jamming intensity,the density of seedlings is increasing but sprouts is reducing.(5) Propagation ability is vigorous,this should be surely used in the population restoration.Rolling soil to promote germination;Pruning the non-motivation arbor and shrub to enlarge the growth space of seedlings;Using thinning to change the light condition and increase flowering and fruiting also germination;Making full use of the characteristics of the asexual propagation to protecting sprouts and impelling population restoration rapidly; Reducing human disturbance and germinating seeds to impel the growth of seedlings.