Abstract: The ecology of zooplanktons in upper and lower reaches of Changjiang River near Gezhou Dam was investigated before and after damming up the River. It was shown that in the middle of the River, the species and amounts of zooplanktons were the same as 20 years ago, but in standing and slowly flowing areas in front of the Dam, they were obviously increased. In the upper reaches from Nanjinguan and lower reaches from Yichang, no or less changes were found.

Key words: Competition, Fraxinus mandshurica, Larix gmelini, Pure stand, Mixed stand