Study On The Age Strcture And Spatial Distribution Pattern Of The Salix Oritrepha Population Of The High-cold Area In Eastern Qilian Mountains

At present,the research on modular plants population,especially,on clonal plants population,has become a advanced subject in the field of plants population ecology.Butresearch of about Salix oritrepha population and plants population age structure and spatial distribution pattern from two levels of genets and ramets has mot been reported so far.In this paper.Salix oritrepha population distributing in high-cold-cloudy-wet valley area of eastern Qilian mountain has been selected as subject to research its age structure and spatial distribution pattern from genets and genets-ramets populations.The results are as follows: I. General characteristic of Salix oritrepha shrub community. Salix oritrepha population is the major dominant species among 15 shrub populations presently,distribute continuously in the altitude range from 3050m to 3450m in the area .Dasiphora fruticosa and Rhododenron eapitatum are sub- dominant species,In other populations Spiraea alpina is widely-distributing species~the remain populations exist as companion or accidental at their respective suitable altitude ranges.The Q -diversity curve of the community vary indistinctly along altitude gradient,but fB -diversity curve decline slowly along altitude gradient from 3050-3350m then ascend till to 3450m. In the comrnunity,interspecific correlation is more complicated and shows positive association~. negative association and neutral relationship.In addition,some species couples such as Salix oritrpha and Caragana jubata show different correlation in different environment.In altitude of 3350m is positive association,while in 3400m ix negative association.So in general,the composition and structure of the community are complexity along altitude gradient. 2.Salix oritrepha age structure is different between geriets population and genet-ramets population.In the genets population,storage of seedlings at age classes 1-5 and 6-10 is much scarce.The age structure distribution genets population is not integrated and its population dynamics appears stability.But the age structure distribution of the genet-ramets population is more integrated and the age structure graph likes triangle.the population dynamics is increasing type. 3 3. The spatial distribution patterns of Salix oritrepha population are different in two levels of genets and genet-ramets populations. The spatial distribution patterns of the genets population are diversity of random, aggregated and uniform dispersion and most of them are random dispersion.But spatial distribution patterms of the genet-ramets population are all aggregated dispersion.The pattern scale and intensity of the genets population increase along altitude gradient but the plot of 3200A,in which it shows small scale and low intensity.The curves of patterm scale and intensity coincide on the whole.The distribution patterns of genet-ramets population are small scale and low intensity. Applying modular structure theories and some biological characteristics of clonal plants to analyze the above results.