The Study On Population Dynamics And Spatial Distribution Pattern Of Main Plants In Xiaolongshan Of Gansu Province

Plant population structure is the individuals’ distribution of the different sizesand ages in populations, reflecting the distribution of the population different ageclasses, site conditions and the relationship between the environment. Quercus alienavar.acuteserata and Quercus liaotungensis are the main vegetation types inxiaolongshan national nature reserve,while Populus davidiana is the built groupspecie. Based on a field investigation,we selected several representative samples inXiaolongshan forest. According to the size class insteading of the age classmethod,the quantity statistics and age composition of Populus davidiana,Quercusliaotungensis and Quercus aliena var.acuteserata were analyzed,the sizestructure,static life tables,survival curve were studied.the the future changes to thestate of fluctuation in the same age class were analyzed combined the Time seriesforecasting model. According to the above analysis,we studied the three populations’successional number changes.The results showed that: Populus davidiana populationbelonged to the declining population and the time series prediction showed the old ageclass number had the growth trend. The size structure of Quercus liaotungensispopulation generally showed a Pyramid shape. Each age class’numbers are little butthe population is currently in the phase of growth. The size structure of Quercusaliena var.acuteserata population showed the population tends to stable,the timeseries prediction showed the population’s overall development is stable.Spatial distribution pattern is the result of long-term influence between thespecies and the environment. In this paper,v/m ratio and T test, negative binomialparameter(k),clumping index(I),Cassie index, patch index(PAI),diffusion index(Iδ) areused to analyze the spatial pattern of the main populations at Xiaolongshan. From thehorizontal direction and elevation gradient the effect mechanism between spatialdistribution pattern and environment were analyzed.Based on the analysis of spatial distribution pattern, the research showed thatPopulus davidiana, Quercus liaotungensis and Quercus aliena var.acuteseratapopulations are aggregated distribution, however the aggregation intensity weredifferent because of the difference in biological characteristics and the biotic andabiotic factors outside. Due to the short of the current theoretical research as well as immutable natural factors,the changes of spatial distribution pattern in the horizontaldirection failed to show consistency. This part remains to be further studied. Spatialdistribution pattern of Populus davidiana,Quercus aliena var.acuteserata and Quercusliaotungensis on the different elevation gradients were also studied, and the changesof spatial distribution pattern in the elevation gradient showed the consistency, that iswith the increase of altitude, the population aggregation degree is more and moreobvious.The Environment affects the plant growth, thereby causing the plantpopulation’s spatial distribution changes. Similarly, different species showed differentenvironment, the difference of population’s spatial distribution pattern can also detectenvironment. The Study on Spatial distribution pattern of different regions anddifferent altitude can provide the theoretical basis for the plant growth and the forestmanagement, which has the vital significance for the coordinated development in theplant and the environment.