Abstract: Investigations on aquatic beetles in static water bodies of Changbai Mountains Nature Reserve and Yiwulushan Mountains show that the species diversity of aquatic beetles is richer in broadleaved-Korean pine forest ecosystem of Changbai Mountains than in agroforestry ecosystem of Yiwulushan Mountains.There are 17 genera and 29 species of aquatic beetles in Changbai Mountains, but only 10 genera and 13 species in Yiwulushan Mounatins.The Shannon diversity index is respectively 2.214 and 1.643 in Changbai Mountains and Yiwulushan Mountains, and the Shannon evenness is 1.260 and 0.640, respectively.The species abundance distribution of aquatic beetles in these two different ecosystems is fitted to logarithmic series distribution.Asmall number of species become the dominant in the two ecosystems.In Changbai Mountains, the dominant species are Hydroglyphus pusillus, Haliplus simplex, and H.pusillus, andin Yiwulushan Mountains, they are Agabus ussuriensis and A.brandti .

Key words: Aquatic beetles, Species diversity, Changbai Mountains, Yiwulushan Mountains, knot angle, mixed effect model, Korean pine, knot diameter, sound knot length, year of death of knot