Abstract: By using composite mesh bag method, the effects of benthic macro-invertebrate in an undisturbed stream and an ecologically restored stream on the decomposition process of Acer buergerianum leaf litter from the Purple Mountain of Nanjing in winter were studied. After 112 days of decomposition, the remaining rate of A. buergerianum leaf litter based on ash-free dry mass was 31〖KG-*2〗- 〖KG-*7〗62%, and the decomposition rate followed a declined exponential equation (P<005). In the flowing water of the undisturbed and ecologically restored streams, the decomposition rate of leaf litter was 00064 d-1 and 00030 d-1; while in the still water of the streams, it was 00016 d-1 and 00018 d-1, respectively. The abundance and biomass of benthic macro-invertebrate were significantly higher in the flowing water of undisturbed stream than in that of ecologically restored stream (P<005), but had no significant differences in the still water of the two streams. Shredders (mainly Asellus sp.) had the highest abundance (704%) in the flowing water of undisturbed stream, while filterers (mainly Tanytarsus sp.) were dominant (378%) in the flowing water of ecologically restored stream. The decomposition rate of the leaf litter was significantly correlated with the richness and abundance of shredder species in flowing water (P<001), but had less correlation with the biomass of the shredders, suggesting that the decomposition of A. buergerianum leaf litter in streams in winter was more dependent on the richness and abundance of shredders.

Key words: benthic invertebrate, eco-environmental quality status, assessment, biotic index, Luoyuan Bay of Fujian.