Abstract:

The wild fruit-tree forest on the north slope of the Ili Valley is a living testament to the vegetative history of the Tianshan region. It is a type of broad-leaved forest appearing in the desert region. However, little is known about interspecific relationships among the major woody species or their process of succession. In 2009, we sampled 10 typical communities and investigated the abundance, height and coverage of woody plants as well as the topographical and soil conditions within each quadrat (20 m×20 m quadrats for trees, 10 m×10 m for shrubs). Interspecific associations were analyzed using continuity corrected χ² test, Pearson correlation and Spearman rank correlation. DCCA (detrended canonical correspondence analysis) was used to identify topographical and soil factors that affected woody plant distributions. The network diagram based on Pearson’s and Spearman’s rank correlation coefficients displayed interspecific relationships clearly. There were negative associations among overall tree or shrub species, indicating a strong independent relationship between species. However, correlation coefficients of most species pairs were insignificant, a fact that may be related to the community’s developmental stage (the early succession stage) and the species’ ecological traits. Positive correlations among the abundance of dominant species were likely due to similar ecological tolerances. This assertion is also supported by our analyses of woody plant distributions and environmental factors. DCCA analysis showed that elevation was the most dominant factor affecting the plant distribution, followed by aspect, soil moisture, organic matter, total nitrogen.

Key words: dominant population, ecological species groups, interspecific relationship, niche overlap, succession, ecological adaptation, environmental interpretation