Abstract: In order to provide a basis for optimizing the structure of ecological breeding ponds for Chinese giant salamander (Andrias davidianus), the change processes of water quality in the ponds were analyzed and the main factors affecting the changes were discussed. Twelve ecological breeding fields in Zhangjiajie City were investigated. The main water quality indexes were mea-sured at the inlet, center and outlet of each pond. The results showed that the water quality indicators met the growth requirement for Chinese giant salamanders and the first standard of breeding water discharge standard from pond except for turbidity. From the inlet to the center, to the outlet of the ecological pond, the water turbidity and dissolved oxygen (DO) showed a decreasing trend while total phosphorus (TP), total nitrogen (TN), chemical oxygen demand (COD) and total hardness (GH) showed an increasing trend. The good selfpurification of water in the ecological breeding ponds made the turbidity fell by 31.7%. Due to the reasonable engineering structure and certain water velocity, TN, TP, COD and GH were kept within the requirements for Chinese giant salamanders. Ecological breeding pools are simple in structure and economic; however, the efficiency of settling pond needs to be further improved to insure water turbidity demand of Chinese giant salamanders.

Key words: bootstrapping, optimal sample size, evergreen broad-leaved forest, soil heterogeneity, sampling design