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Study on Population Structure and Dynamics of Populus Euphratica in Jinta and Dingxin Oasis, Gansu Province

Author: ZhuXiaoJuan
Tutor: LiuPuXing
School: Northwest Normal University
Course: Physical Geography
Keywords: Jinta and Dingxin Oasis populus euphratica population structure quantitative dynamics succession
CLC: S792.11
Type: Master's thesis
Year: 2013
Downloads: 8
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Abstract


Populus euphratica is salicaceae populus’s oldest plant, Pliocene ancientMediterranean relic species, which is most widely distributed in central Asia’s desert.As one of the rare and endangered species, Populus euphratica is national third-classprotective plant, and was listed in the national endangered species protection list byCN. In China, its main distribution regions include Tarim Rive in Xinjiang province,Ejina Natural Reserve in Inner Mongoli province, Hexi corridor in Gansu province,and so on. Due to deficiency of a thorough protection mechanism, a large number ofPopulus euphratica had suffered different extent destroy. Meanwhile, the ecologicalenvironment is getting worse, and the propagation and survival turned out to be moredifficult, thus, the number of Populus euphratica is getting less and less. Populuseuphratica is an unique precious forest resource in desert areas. It plays an importantrole in stabilizing of the ecological balance of desert river areas, wind prevention andsand-fixation, improving oasis weather condition, and preserving fertile soil. So itseems to urgently to get down to protection this species. Thus, we take the naturalPopulus euphratica forests of Jinta-Dingxin Oasis in Gansu province as the study area.Classical statistical and investigation were used to explore population structure anddynamics of Populus euphratica during the growing season of natural Populuseuphratica in Jinta-Dinxing Oasis. In order to provide scientific basis and protectionfor the ecological environment of Populus euphratica in Jinta-Dinxing Oasis, to makerational use of water resources and the sustainable development. The conclusion is asfollowing:(1) The characteristics of the size and age structure of Populus euphraticapopulation were obviously different under different habitats in Jinta-Dingxin Oasis.Populus euphratica population in Dingxin Oasis growth better than in Jinta oasis.Populus euphratica in density, height and DBH in GBCD plot are slightly better thansame in Jinta oasis SCCD plot, at the same time, Populus euphratica population inGBCD plot will tend to increase, while Populus euphratica population in SCCD willtend to a decline status because of lacking seedlings; Populus euphratica populationseedling is rich in XHCD plot which belongs to increasing population. However, theother sample to the succession of populus euphratica tended to decline due to lack of seedlings for both except XHCD plot in Jinta oasis.(2) The density, diameter at breast height, height and age structure of naturalPopulus euphratica population is mainly affected by topography, soil, water, salt andthe influence of underlying surface factors such as human activities. Underlyingsurface factor under different habitats have a quite different, which directly lead topopulation structure differences. In a word, Populus euphratica population structuredifferences is the result of common action with the natural environmental factors andhuman activities.(3) The natural Populus euphratica population survival analysis shows: Thenature of Populus euphratica population in Jinta-Dingxin Oasis is not motionaless allthe time, but in the increace or decline rapidly stage. There are different developmentand change status of Populus euphratica population under different habitats inJinta-Dingxin Oasis.(4) The static life table of Populus euphratica population clearly shows: whenPopulus euphratica population survival pressure is smaller, life expectancy value isbigger; With the increase of age class and age of Populus euphratica population, thepopulation’s average life expectancy value is shrinking. Mortality rate of populationincreases highly in early time, stability later, and higherly at last in GBCD plot;Mortality rates of Populus euphratica population have been low in SCCD plot, buthigher in mature period; NTWD Populus euphratica population Early mortality rateof Populus euphratica population is higher and lower late in mature period; There is asudden high mortality about HSCD Populus euphratica population from thevegetative stage to reproductive cycle; DZZD Populus euphratica population infancymortality rate is high, the decline in death rates as a rapid development period ofnutrition; There is a high death rates in young tree growth stage, late to stabilize inXHCD plot; WXCD Populus euphratica population mortality in mature period is onthe high side.(5) The survival curves of the Populus euphratica population clearly shows: Thesurvival curves of the population in GBCD plot clearly conformed to the type of“increasing”; The survival curves of SCCD Populus euphratica population conformedto the type of “DeeveyＩ”, indicating a declining population; The survival curves of the population in NTWD, HSCD, DZZD and WXCD plot of Jinta Oasis clearlyconformed to the type of “declining”, indicating a declining population. The contraryis the case that the survival curves of XHCD plot in Jinta Oasis conformed to the typeof “increasing”, indicating a increasing population.(6) The statistical results of quantitative dynamics of the Populus euphraticapopulation indicated that the dynamic indices of young trees and middle age treeswere negative values with big change extent, and the dynamic indices of large and oldtrees were positive values with small change extent. It also displayed a declining orincreasing structure of Populus euphratica population in Jinta-Dingxin Oasis. Theresult of the dynamics quantitative estimate indicated: Except for XHCD, GBCD plot,Populus euphratica population all the plot in Jinta-Dingxin Oasis will tend to declinestatus because of lacking seedings in the future, and the speed of the declinesuccession is different. The speed of the decline succession in Jinta-Dingxin Oasisshow: SCCD＞DZZD＞NTWD＞HSCD＞WXCD.Both GBCD and XHCD plots’sPopulus euphratica population in Jinta-Dingxin Oasis tend to increase dynamicrelationship, but development of stability of Populus euphratica population in GBCDplot is better than in XHCD plot.

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CLC: > Agricultural Sciences > Forestry > Forest tree species > Broad-leaved trees > Young
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