Study On The Effects Of Geologic Background Factors On The Potential Distribution Of Acer Pentaphyllum

Acer pentaphyllum is endemic plants in sichuan province,the wild natural distribution is extremely scarce,belongs to the national minimum plant population.For a long time,due to the effect of human activities such as deforestation and hydropower station construction,the plant resources of Acer pentaphyllum and their habitats suffered severe damage,combined with the power station completed water storage will cause the habitats of Acer pentaphyllum decline sharply.How to determine the ex-situ conservation area of Acer pentaphyllum and effectively protect the Acer pentaphyllum has become the current scientific problems to be solved urgently.In this paper,on the basis of field investigation,doing research on the natural population age structure and populations dynamic of Acer pentaphyllum,and around the relationship between the actual distribution and geological factors,using the maximum entropy(MaxEnt)model to built Acer pentaphyllum climate niche model,physiognomy niche model,soil niche model,stratum niche model,lithology niche model,and predict potential distribution probability of Acer pentaphyllum in their distribution area,then divide the suitability grade of Acer pentaphyllum and overlay the grid layers of probability of potential distribution probability,acquire the range of suitable distribution area,and put forward the protection strategy.Through the research can gain the results as follows:(1)Acer pentaphyllum natural population age structure and populations dynamic studies have shown that the age structure of Acer pentaphyllum is a pyramid shape,that is,the number of middle aged was larger than that of young seedling and old individuals,indicating that the population was in an stable status.The survival curve in this population appeared to be a Deevey-?type,with a peak of mortality in size class ?.It can be concluded that the population size of Acer pentaphyllum reduced in early stage,stablized in middle stage and fell rapidly in last stage.(2)The ecological niche model of clime,ecological niche model of physiognomy,ecological niche model of soil,ecological niche model of stratum and ecological niche model of lithology have been established in Acer pentaphyllum habitat.Through analysis of above models,the main conclusions are as follows:Through the analysis of ecological niche model of clime,the dominant factors of influence the distribution of Acer pentaphyllum are annual precipitation(58.1%),precipitation of coldest quarter(37.8%),precipitation of driest month(2.2%),mean temperature of driest quarter(1.6%),temperature seasonality(0.2%),Response curves show that the places of annual precipitation is 1100 mm and precipitation of coldest quarter is greater than 265 mm are most suitable for the growth of Acer pentaphyllum;Acer pentaphyllum demands for humidity is low in autumn and winter,and much rain is bad for Acer pentaphyllum;greater variation in temperature seasonality is not conducive to the growth and distribution of Acer pentaphyllum.Through the analysis of ecological niche model of physiognomy,dem and slope are the main landscape factors to affect the distribution of Acer pentaphyllum.The region of elevation range is from 2000 m to 3600 m and slope value is from 40° to 60° is most suitable for the growth of Acer pentaphyllum.O ver all,Acer pentaphyllum tends to choose the areas of higher televation and topography steep.Through the analysis of ecological niche model of soil,the dominant factors of influence the distribution o f Acer pentaphyllum are exchangeable sodium percentage in the topsoil(59.7%),total exchangeable bases in the topsoil(13.4%),Calcium carbonate content in the topsoil(12.7%),Texture class name and code(10.6%)and sulfate content(3.6%).And the response curves show that Acer pentaphyllum is suitable for growth in the low salinity and loam and clay loam powder more area.Through the analysis of ecological niche model of stratum and lithology,Acer pentaphyllum is mainly distributed in Triassic and five kinds of lithology,including granite,granodiorite,sandstone,limestone and sandstonean,which probability in the granodiorite probability is the largest.(3)The Acer pentaphyllum potential suitable area range can be derived using fuzzy superposition method.After classification and statistics for each grade of the suitable area,the most suitable area for Acer pentaphyllum is obtained,that is 20446.3779 km~2,which accounted for 4.21% of Sichuan,are mainly distributed in the most parts of Mu li County,Yan yuan County,Jiu long County,Ya jiang County,Kang ding County,and small area of Dao cheng County,Xiang cheng County,Ba tang County,De ge County,Bai yu County and Mian ning County;the suitable area is 30925.1700 km~2,which accounted for 6.36% of Sichuan;the relative suitable area is 76531.3464 km~2,which accounted for 15.75% of Schuan;unsuitable area is 358097.1057 km~2,which accounted for 73.68% of Sichuan province's area.