Abstract: Fallen tree has an important role in forest ecosystem, especially in hydrology of mountainous forest ecosystem with water and soil conservation functions. The samples of fallen trees of Picea schrenkiana var. tianschanica (Rupr.) Chen et Fu were collected from 5 areas (Zhaosu, Xinyuan, Hutubi, Tianchi and Qitai) across nine longitudes in the forest region in the Tianshan Mountains so as to understand the water retention capacity and its hydrological function in forest in the Tianshan Mountains. These samples were treated with soaking simulation. The results showed that, in the soaking process, the water retention capacity, specific retention and water retention capability of the P. schrenkiana fallen trees at 5 sampling sites were all increased with the increase of soaking time. The relationship between water retention capacity (Q) and soaking time ([WTBX]t[WTBZ]) could be fitted by =aln t+b. But the water absorbing rate was decreased with the increase of soaking time from the decomposition level I to V. The relationship between water absorbing rate (V) and soaking time (t)could be fitted by V=c t^-d. The relationship between water retention capacity(Q′)and decomposition level (x could be fitted by Q′=ex²+fx+g. So there was a significant difference of water retention capacity among P. schrenkiana fallen trees at 5 sampling sites. The study results offered the foundational data for further study on hydrological functions in forest in the Tianshan Mountains.

Key words: Picea schrenkiana var. tianschanica, fallen tree, water retention capacity, specific retention, water absorbing rate, Tianshan Mountains