Analysis Of Population Characteristics Of Ulmus Pumila Sparse Forest In Hunshandake Sandy Land

Ulmus pumila sparse forest in Hunshandake Sandy land which grows on pure sand is a kind of unique super-zonal climate vegetation of sandy forest.It is an important natural resource which has extremely important social,economic and ecological value.The dissertation studied the distribution,characteristics and its relationship with climate systematically by using 3s technology,combining field investigation,and studying home sparse forest.At the same time,it analyzed the population dynamics,distribution pattern and regular pattern.The main results are as follows:1.Aging structure of Ulmus pumila populations in Hunshandake Sandy land is unreasonable,much of which is declining(began from 40 years ago).Natural regeneration of Ulmus pumila population is extremely bad.Ulmus pumila which distributes on dune can renew better than that in the lowland between dunes:The mortality in the stage of young tree is much higher(almost60%-90%).The survivor curve of Ulmus pumila populations is close to Deeveyâ…¡,and it shows Deeveyâ…¢on various plots.2.Ulmus pumila sparse forest in Hunshandake Sandy land distributes widely in the middle and the east,most are in Zhenglan county.The analysis of climate shows that the distribution of Ulmus pumila sparse forest is the result of all kinds of climate factors,but not because of a certain factor.The distribution of Ulmus pumila sparse forest is mainly influenced by Terrain,underground water,and rainfall,among which precipitation is the most important. 3.Under different yardsticks Ulmus pumila sparse forest in Hunshandake Sandy land shows contagious distribution.With the increase of yardstick,the contagious intensity increases gradually.With the growth of it,Ulmus pumila in the middle east spreads gradually,but it gathers first,then spreads in the western Tala habitat. Meanwhile,Ulmuspumila growing on dunes gathers first,then spreads.4.The patch of Ulmus pumila sparse forest in Hunshandake Sandy land is about 800 m~2,while the patch of Ulmus pumila sparse forest in the west Tala habitat is bigger than 1600 m~2.5.The pattern intensity of Ulmus pumila sparse forest in Hunshandake Sandy land decreases with the increase of research yardstick.On the yardstick of 800 m~2 it usually appears little peak value,and the pattern intensity of Ulmus pumila populations on dune habitat is higher than Ulmus pumila populations in Tala habitat. From west to east,The pattern intensity of Ulmus pumila sparse forest shows regular pattern with the changes of environment.6.In the ecosystem of Ulmus pumila sparse forest in Hunshandake Sandy land, although Ulmus pumila is constructive species,it occupies less space.And with the changes of environmental condition,its changing laws are as follows:(1) From the east to west,the occupation ability of Ulmus pumila sparse forest in Tala habitat first increase then decrease;while on dune habitat it is the opposite.(2)The occupation ability of Ulmus pumila sparse forest in Tala habitat is higher than that on dune habitat.(3)The yardstick changes of the pattern intensity of Ulmus pumila sparse forest are not obvious,and there is no big difference in uniformity differences of distribution in the degree.