Heterogeneity Of Community Structure And Species Diversity Of Picea Schrenkiana Var. Tianschanica In The Tianshan Mountains, Northwest China

To understand the law of spatial pattern heterogeneity in the Pices Schrenkiana var.tianschanica forest,5positions from the west to east in the Tianshan Mountains (such asZhaosu, Xinyuan, Hutubi, Tianchi and Qitai) to set sample sites where the elevation is from1700m to2900m were seleced.(1) The mean value of uniform angle index was0.545for the P. schrenkiana forest in the5sample sites, which means that the P. schrenkiana natural forest appeared as reuniondistribution. The mean value of neighbourhood comparison was0.490, which means thatgrowth state of the P. schrenkiana forest was between a sub-dominant state and a moderationstate, which reprentages significant changes from moderation state to sub-dominant tomoderation state within5sample sites form west to east in the Tianshan Mountains.(2) From the altitudinal pattern, the results of values of uniform angle index changed withthe variation of elevation in5sample sites showed that the distribution of P. schrenkianaforest appeared alternates change from aggregate to random, to aggregate, and to random. Atthe same time, the variation of neighbourhood comparison presented that, the growth state ofthe P. schrenkiana forest changed from the sub-dominant to moderation state to sub-dominantto bad state. The changes of the mean values of uniform angle index was not significantlywithin5sample sites, which showed growth distribution of P. schrenkiana forest appeared asreunion. But the variation of the mean value of neighbourhood comparisom had significantchanges from sub-dominant to moderation state to sub-dominan within5sample sites formwest to east in the Tianshan Mountains.(3) Analyzed the different species of the five sample sites, the results showed that thediversity of all the arbor layer of the P. schrenkiana forests had196kinds of species,belonging to44families and117ganus.7kinds of species of arbor layer were belonged to4families and5ganus. Sherb layers contained31kinds of species, belonging to7families and14ganus. Hrub layers contained158kinds of species, belonging to36families and101ganus.The composition of P. schrenkiana forests was relatively simple. And P. schrenkiana holds anabsolute advantange in tree number, density, breast-height basal area.(4) The order of the total percentages for seedlings and saplings in the5differentinvestigative sites were: Xinyuan﹥Tianchi﹥Zhaosu﹥Hutubi﹥Qitai; and for the small logswere: Zhaosu﹥Xinyuan﹥Qitai﹥Hutubi﹥Tianchi; for the mediums were: Zhaosu﹥Tianchi﹥Hutubi﹥Qitai﹥Xinyuan; for the larges were: Qitai﹥Hutubi﹥Xinyuan﹥Tianchi﹥Zhaosu. The diameter class distribution of P. schrenkiana appear as the normal distribution with the increase of elevation in the5different investigative sites. The number of seedlingsand saplings, small, medium and large logs were all showed normal distribution with thechange of longitude.(5) The abundance index of different index in the P. schrenkiana forests showed that: herblayer>sherb layer>arbor layer. The Shannon-Wiener index, Simpson index, and Hurlbertindex of herb layers are all the highest in the three layers. The shurb layers have little species,so its abundance index is low. But Lonicera hispida take an dominant. The arbor layer isuneven distribution but the simpson dominance index higher than the others, which meansrhat the dominant position of P. schrenkiana is very obvious, position in shurb layer, for itssimpson dominance index high.(6) The abundance index and diversity index are higher in the arbor layer of the P.schrenkiana forest at the lower altitudes, and the abundance index and diversity index werelittle correlated to elevation, and they decreased slightly with the increase of altitude. Nosignificant changes in the two index were found in the most suitable growing regions for P.schrenkiana forest. The evenness index appeared from increasing to reducing at the altitudebetween1750and2450m. But it became increase between2450and2550m, and thedominance index was the largest at the altitude between2550and2850m. The abundanceindex, evenness index, and diversity index in the shrub layer were larger at the lower andhigher altitude, but which were smaller at the medium. The three index in the herb layerwithout significant change at the altitude from1750to2250m, however they turned out to bedecreasing as the increase of elevation at the higher altitude.(7) The diversity of the arbor layer of the P. schrenkiana forests were varied as the changeof latitude, From west to east in the Tianshan mountains, the abundance index, evenness indexand diversity index increased at the beginning, and then which turned to be decreasing. Theabundance index in the herb and shrub layers was higher at east and west sites but lower at thecentral as the change of the latitude. There was no significant difference between dominanceindex and diversity index t. The results show that the P. schrenkiana forests growing better inthe central than those in the east and west.