| The study region lies in 34° 0' -34° 40' north latitude, 105° 30' -106° 30' east longitude. The relative height is 500-100m. The region lies in intermediatal zone from southern part of warm temperate zone to the north part of subtropical zone and from Qinzang plateau to Loess plateau to Sichuan basin. The climate is warm and moist, most of the region is continental monsoon climate,the annual temperature is 7-12 ℃ ,the extremely low temperature is-23. 2℃, the accumulative temperature of ≥10℃ is 2444-3825 ℃ ,the annual rainfall is 460-800mm and it focuses in July,August and September, the rainfall in spring and autumn accounts for 70-80% of rainfall of all the year round and it changes heavily annually;the annual evaporation is 989-1658mm, the relative humidity is 68-78, the annual sunlight is 1520-2313 hours, the unfrosted day is 120-218days. The zonal soil of region is the gray-cinnamon soil in north of Qinling and the yellow-cinnamon soil in south of Qinling; the soil distribution is distinct in perpendicularity, they are calcic cinnamon soil, alpine cinnamon soil, alpine luvic cinnamon soil, alpine brown soil, alpine dark brown soil, alpine meadow brown soil, alpine meadow soil, sub-alpine meadow steppe soil from low attitude to high attitude on north slope and they are yellow cinnamon soil, yellow brown soil, alpine brown soil, dark brown soil from down to up on south slope. The thickness of soil is 30-60cm, the soil is humidity, PH is 6.5-7.5 and its texture is soil, the nitrogen content is modest, the phosphor and kalium content are low.The paper studies the biodiversity characteristics, the relationship of the biodiversity and ecological process of Quercus aliena var. acutesrata community. I get the conclusion through plenty of field survey and data analysis.(1).The PCA analysis shows that The Quercus aliena var. acutesrata contributes the most to The Quercus dominance community, it is 98.3%; The Quercus aliena var. acutesrata, Carpinus turczaninowii, Lindera umbelleta and Cornus hemsleyi have the equal contribution to the Quercus aliena var. acutesrata and other low trees mixed community; Carpinus turczaninowii, Tilia dictyoneura and Lindera umbelleta have equal contribution to mixed trees community. (2)The dominance tree is evidence in the Quercus aliena var. acutesrata community. There are 40 tree species existing in surveyed sample spots, the number of 10 largest important value trees accounts for 86.12% of all the number of trees which are surveyed. The tree number decreases with the DBH classes increasing in tree layer, the tree number is the most in <4cm DBH class, then it intensely descends. The number with the DBH class increasING shows "inverse J" model, it can draft with y=32.113-1.059x2+0.007x (R2=0.96,n=16), the species richness decreases with the DBH increasing. The number of species with the DBH increasing shows "inverse J" model, it can draft with y=1.491x0.474(R2=0.982,n=6). The species richness with the height increasing shows "inverse J" model, it can draft with y=4.9667x -0.4088x2+0.0079x3+14.3484(R2=0.96,n=6). The density with the biodiversity increasing shows "M" model.(3) The correlation analysis shows: elevation, slope, development stage and biomass are main factors which affect the biodiversity pattern in the research region.The biodiversity of the Quercus aliena var. acutesrata community shows the patterns with the elevation and slope affecting: On sunny slope, the species diversity increases with the elevation increasing below the attitude of 1640m and its climax is at this attitude(the diversity index H=1.68),upward this point, the diversity index descends slowly. The evenness shows ascend trend with the elevation upward, its climax point at 1800m(the evenness index Jsw=0.78), then descending after this point. The dominance is bigger at low attitude(1500-1600m) and descends with the elevation upward. On shade slope, the diversity waves with the attitude, the maximal diversity index H=2.079 is at point of1860m, the evenness index is not correlate to elevat...
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