Study on Plant Species Composition and Richness of the Mountain Coniferous Forests in Xinjiang

After carrying out the survey of 122 plots at 11 locations in the Altay Mountains (Altay),Kunlun Mountains (KL in abbreviation,the same below),and northern and southern slopes of the Tianshan Mountains (NT and ST respectively) in Xinjiang,it is found that the plant species richness of coniferous forests in Altay is significantly higher than that in ST and KL; plant species richness of Picea schrenkiana forests is significantly lower than that of P. obovata forests. According to the Sorensen Index,the plant composition in ST and KL is similar,and it is also similar in Altay and NT; the plant composition in Larix sibirica forests and Picea obovata forests are similar,but that in Juniperus centrasiatica and J. jarkendensis forests is quite different from that in Pinus sibirica and Abies sibirica forests,L. sibirica forests and Picea obovata forests. Species richness decreases significantly with the increase of altitude and mean annual temperature (MAT) but increases significantly with the increase of latitudes in whole Xinjiang. Species richness decreases with the increase of total basal area (TBA) in Altay and KL. According to the GLM (General Linear Model),aspect of plots (ASP) affects significantly the plant species richness in whole Xinjiang. Forest type and TBA also affects significantly the plant species richness in north Xinjiang. While in south Xinjiang,the plant species richness is significantly affected by annual precipitation (AP),slope position (POS) and TBA.