Study On Structure And Spatial Distribution Patterns Of Populus Euphratica Populations From Different Oasis

The oasis of Jinta, Minqin and Dingxin which belonged to the downstream’s Lairiver, Heihe river, Shiyang river respectively, and the edge of Badain Jaran Desert, islocated in the central-eastern of Hexi Corridor. The oasis of Jinta, Dingxin andMinqin is the natural barrier to resistance the sand in the Hexi Corridor. The Populuseuphratica as a natural arbor and advantage to build group of tree species had somespecial features in salt resistance, wind resistance, resistance to atmospheric drought,which played an important irreplaceable rule in maintaining the ecological balance ofthe region area. Accordingly, in this paper, based on the theory of statistics andpopulation ecology, using the means of the plant population structure and spatialpattern，combined with the oasis of Jinta, Minqin and Dingxin’s related statistics dateof literature review and the field survey work, discussed the population structure andspatial pattern characteristics, and study on the comparison of the three oasis in thecentral-eastern of Hexi Corridor to clarify the Populus euphratica forest’scharacteristics of the populations structure and the spatial pattern in the area, reveaedthe quantity characteristic and development trend of Populus euphratica forest in thethe central-eastern of Hexi Corridor, in order to understand the Populus euphraticaforest structural features, predict the Populus euphratica forest’s development trend.Accordingly, the scientific decision-making was provided in protecting Populuseuphratica forest in the area, updating and rejuvenation and constructing the oasis’secological environment. The main conclusions are as follows：(1)The characteristics of age structure of Populus euphratica population is thatthe age structure of Populus euphratica populations was different in the differentoasis, and it was obviously different under different plots in the same oasis. In the fivesample plots of Jinta Oasis, The age structure of Populus euphratica populations ofXHCD population showed a pyramidal type with an increasing population. The otherfour plots of Populus euphratica populations in Jinta Oasis showed different degreesof declining population. The structure of Populus euphratica populations in the twoplots in Dingxin Oasis was significantly different. The GBCD population showed apyramidal type with increasing population, but SCCD population showed a type ofinverted pyramid with declining population. The three plots of Populus euphratica populations in Minqin Oasis showed different degrees of declining population.Themost incomplete of the age structure of Populus euphratica populations was SWCD.(2) In general, the spatial distribution of Populus euphratica populationsconformed to clumped distribution pattern in the ten sample plots which blonged tothe three oasis, but but different plot showed different aggregation intensity indifferent oasis and different scale. The same area of100m×100m in the three plots ofJinta showed different level of aggregation, and which was WXCD>NTWD>HSCD.The area of64m×64m in the two plots of Jinta were also different, which wasXHCD>DZZD. The level of aggregation was GBCD>SCCD in same area of100m×100m in the2plots of Dingxin. In the three plots of Minqin, each plot spacedthe same area, was0.4096hm~2. Different plot showed different level of aggregation.We found that the level of aggregation of Populus euphratica populations SCKDpopulations was the highest, followed by the SWCD and JHCD plot.(3)The average height of Populus euphratica populations in the Oasis of Jinta,Dingxin and Minqin were respectively5.75m,6.33m and5.91m. The minimumaverage height of Populus euphratica populations was3.48m, which was the plot ofXHCD in the Oasis of Jinta.The highest average height of Populus euphraticapopulations in the three oasis was9.39m, which was the plot of NTWD in the JintaOasis. The average height of Populus euphratica populations about the other threeplots in Jinta Oasis was respectively4.65m,6.25m and4.95m. The average height ofPopulus euphratica populations in the SCCD and GBCD which belonged to DingxinOasis were respectively7.36m and5.29m. The highest average height of Populuseuphratica populations in the Minqin Oasis was7.72m, it was the plot of SCKD. Theaverage height of Populus euphratica populations about the other two plots in MinqinOasis was same, which is5.01m. The most populous population density of Populuseuphratica7.03trees/100m~2, which was XHCD, Jinta Oasis. The population densityof Populus euphratica in the other four plots of Jinta were1.13trees/100m~2,1.95trees/100m~2,1.59trees/100m~2and2.2trees/100m~2.The population density of Populuseuphratica in GBCD was more populous than that in the SSCD, Dingxin Oasis. Thepopulation density of Populus euphratica in the three plots of Minqin Oasia wererespectively5.77trees/100m~2,2.83trees/100m~2and1.61trees/100m~2. (4) There are differences for the structure and spatial distribution patterns ofPopulus euphratica populations from different oasis. This is the result ofcomprehensive function of Populus euphratica biological characteristics, habitatconditions (underlying surface landform, hydrology, soil, etc.) and human activities.WXCD sample area is one of the most complete age structure of populus euphraticapopulation in three100m×100m sample plots in jinta oasis, this is mainly due to theWXCD located inside the oasis, close to water, water conditions is better, whileHSCD and NTWD located in the downstream end of Tao Lai river, far away fromwater, the gobi desert widely distributed. The XHCD sample area is the only sampleto show the growth in two64m×64m sample area in Jinta oasis, and its stand densityis the biggest of10samples area, its tree height is3.48m which is the lowest in allsamples. Due mainly to the sample area is flat and the soil water content is larger, andthe area is good to grow the populus euphratica. The age population structure ofPopulus euphratica was incomplete in the plot of DZZD, Jinta Oasis, which lack ofthe rank of Ⅲ. It is mainly because of the natural thinning in the process of thePopulus euphratica’s growth and the plants natural phenomenon of training. Thebetter growth of Populus euphratica populations was GBCD, Dingxin Oasis.Thereason is that the plot of GBCD was at the relatively upstream of Heihe River, it hasrelatively good soil moisture conditions, and its polysalt phenomenon was less seriousthan SCCD. The fact that we have verified by the experiment.The worst growth ofPopulus euphratica populations was SWCD, Minqin Oasis.There was a Phenomenonof that more dead trees, and dead branchs in the treetop were in the plot of SWCD.The reason total salt content was between1.98%~3.42%, when it reached more than3.23%, normal growth of Populus euphratica would be inhibited. We found that it ismore complete the age population structure of Pupulus enphratica in JHCD thanSWCD, it owing to the higher soil water content in JHCD than SWCD.