Abstract: Ili Valley in Xinjiang is one of the distribution centers of wild fruit species in the world. In this study, the species richness and structure of wild fruit forests in the Ili Valley were analyzed based on the investigated data from 67 sample plots. The results show that Juglans regia, Malus sieversii, Armeniaca vulgaris and Prunus sogdiana forests are the main wild fruit forests in the Ili Valley. In total, 207 species in 141 genera and 46 families have been recorded. Species richness is higher in the A. vulgaris and P. sogdiana forests than that in the J. regia and M. sieversii forests. Stem density of the M. sieversii forests is significantly higher than that of the A. vulgaris forests. Mean stem height (H_m) of the J. regia forests is higher than that of the P. sogdiana forests. There is no significant difference in mean stem diameter at breast height (D_m) among the four forest types. Species richness tends to decrease, whereas H_m and D_m tend to increase, and there is no significant change of stem density with the increase of altitude. The results of a canonical correspondence analysis (CCA) reveal that the J. regia forests are mainly distributed in the warm areas, whereas the M. sieversii forests in the cold regions, and the A. vulgaris forests widely across the Ili Valley. Compared with other three forest types, P. sogdiana forests are only distributed in the mountainous areas in Huocheng County, where water availability is relatively high. The wild fruit forests in the Ili Valley are suffering from the severe destruction due to the intensive human activities, and they should be protected in some ways, such as the collection of germplasm resources and ex-situ conservation.

Key words: altitude, climate factor, community structure, species richness, wild fruit forest, Ili Valley, Xinjiang