Abstract: In order to study the influence of environmental factors on community structure and distribution of hyporheic macroinvertebrates at a microscale, we chose five sites to investigate hyporheic macroinvertebrates and habitat characteristics in the upper reaches of Heishuitan River. Our results indicated that a total of 29 species of macroinvertebrates were collected, and aquatic insects were the dominant group. The density, biomass and richness of macroinvertebrates decreased with the bed depth. The composition and distribution of the hyporheic macroinvertebrates were determined by median diameter (D₅₀) of sediments, vertical hydrological gradient (VHG) and vertical hydraulic conductivity (K_v), and D₅₀ was the most important factor. Besides, the food sources and the interactions of macroinvertebrates may also play important roles in affecting community structure of hyporheic macroinvertebrates. All of these factors formed a complex natural filter to control the composition and distribution of the hyporheic macroinvertebrates.

Key words: paddy soil, priming effect, organic carbon mineralization, phosphorus addition