A unique mountainous vertical distribution patterns and related environmental interpretation – A case study on the northern slope of the Ili River Valley

Patterns of plant diversity and soil factors along the altitude gradient on the northern slope of ili river valley were examined. plant and environment characteristics were surveyed from 1000~2200 m. there were a total of 155 vascular plant,133 herbage,18 shrub,and 7 tree species in 44 sampled plots. the plant richness of vegetation types generally showed a special pattern along altitude,with a bimodal change of plant species number at 100m intervals of altitude samples. the two belts of higher plant richness were in transient areas between vegetation types,the first in areas from low-mountain desert to forest,and the other from dry grass to coniferous forest. matching the change of richness of plant species to environmental factors along altitude by gam model and relation analysis revealed that the environmental factors controlling species richness and their patterns were the combined effects of soil salt and nutrition. water was more important at lower altitude,and temperature at higher altitude,the role of the inversion layer at high altitude coniferous forest species diversity appearing to rise. soil nutrition and salt also showed a similar distribution pattern of diversity. especially,diversity index and soil salinity showed a strong correlation. this study provides insights into plant diversity conservation of ili river valley in tianshan mountain. © 2016,pakistan botanical society. all rights reserved.