Study On Population Dynamics And Ecological Adaptation Of Rare Branch Ornamental Liriodendron Chinense

Liriodendron chinense is an endemic plant in Sichuan.Its natural distribution in the wild is extremely rare and it belongs to the national minimum population.For a long time,due to human activities such as deforestation and hydropower station construction,Liriodendron chinense plant resources and its habitats have been severely damaged.In addition,the completion of water storage during the construction of the power station will result in a sharp decline in the habitat of Liriodendron tulipifera.How to determine the area of ex situ conservation of Liriodendron chinense and reasonable and effective protection of Liriodendron tulip resources has become a scientific problem that needs to be solved urgently.Based on the field investigation in the field,the paper studies the dynamics of the age structure and population of the natural population of Liriodendron chinense,and builds a maximum entropy(MaxEnt)model to model the climate of Liriodendron chinense,focusing on the correlation between actual distribution and geological factors.Niche models,geomorphological niche models,soil niche models,stratigraphic ecology models,and lithologic niche models predict the potential of liriodendron chinense in the distribution area under the constraints of climate,geomorphology,soil,stratum and lithology.Based on the distribution probability,each potential distribution probability raster layer is fuzzy superposed,and the suitability level of Liriodendron tulipifera is divided,and the potential distribution range of Liriodendron tulipifera is obtained,and a protection strategy is proposed.The following research results were obtained through research:(1)The study on the age structure and quantity dynamics of natural populations of Liriodendron tulipifera shows that the age-class structure of Liriodendron tulipifera is a typical pyramid type.Individuals are concentrated in the young and middle-aged,and the proportion of old individuals is relatively small,indicating a stable population.At the age of the fourth age,the population had a peak of death.The survival curve of the population tends to be Deevey-II type;it has the characteristics of early population reduction,stable in the middle and late period,and late recession.(2)Analysis of the climate niche model,geomorphological niche model,soil niche model,and stratigraphic lithology niche model of Liriodendron chinense:From the climatic niche model,the dominant factor affecting the distribution of Liriodendron chinense is the ratio of day-night and year-to-year temperature differences bio-3(29.9%),the coldest quarterly average temperature bio-11(23.4%),and the variance of rainfall changes bio-15(18.7%),driest month rainfall bio-14(9.4%),and the coldest quarter average rainfall bio-19(5.2%).The response curve of each dominant factor indicates that the average annual rainfall at 1800 mm is most suitable for the survival of Liriodendron chinense.The temperature requirement of Liriodendron tulipifera is relatively low.Proper temperature increase promotes the survival probability of the plant.Excessive temperature will reduce the survival rate of Liriodendron tulipifera.From the analysis of geomorphological niche models,elevation and slope are the main geomorphological factors that affect the distribution of Liriodendron tulipifera.The optimum range for the distribution of Liriodendron tulipifera is 300~2000,and the slope value range is 40°-55°.Overall,Liriodendron tend to choose low-medium and steep terrain.From the analysis of the soil niche model,the importance of the dominant factors was: soil basic saturation(45.9%),soil available water content(36.5%),soil texture classification(9.2%),soil exchangeable sodium salt(3.2%)),soil volume fraction of gravel(3.1%),soil bulk density(1.1%).And the response curves of each factor indicated that Liriodendron chinense was suitable for growing in sandy soil.From the analysis of stratigraphic lithology niche models,Liriodendron chinense is mainly distributed in the Jurassic,Carboniferous-Permian,Devonian and metamorphic pebbly sandstone,sandstone slate interbedded,sandstone,altered sandstone ash On the four lithologies of rocks,there is the highest probability of existence on metamorphic pebbly sandstones.(3)Using the fuzzy superposition method to obtain the map of potential suitability of Liriodendron chinense,the classification and calculation of the area of each suitable grade,and the optimum area of Liriodendron chinense is 3133.54 km2,accounting for 0.65 of the entire province.%,mainly distributed in Xuzhou County,Hejiang County,Gulin County,Pazhong Nanjiang County,Tongjiang County,Dazhou City,Wanyuan City,a small part of the six counties.The suitable area is 6445.489433 km2,accounting for 1.33% of the total area of the province;the area of suitable area is 27257.71 km2,accounting for 5.63% of the whole province;the area of unfavorable area is 447186.03 km2,accounting for 92.39% of the total area of the province.