关键词: 凋落叶分解, 长白山, 底栖动物, 冻结初期, 凋落叶混合效应

Abstract: A field simulated experiment was conducted to study the effects of nitrogen deposition on the litter production of a subtropical evergreen broad-leaved forest. Treatments were designed as CK (0 kg·hm^-2·a^-1), low N (LN, 50 kg·hm^-2·a^-1), high N (HN, 100 kg·hm^-2·a^-1), high N+P (HN+P, 100 kg N·hm^-2·a^-1 + 50 kg P·hm^-2·a^-1), with three replicates for each treatment. The results from a twoyear observation showed that the annual litterfall production amounts were 7.78, 8.81, 9.08 and 9.41 t·hm^-2 for CK, LN, HN and HN+P, respectively. The N deposition did not significantly increase litterfall production in this subtropical forest. However, HN treatment decreased the production of foliar litterfall compared to LN treatment. The production of either foliar, branch or total litterfall was higher in HN+P treatment than in HN and LN treatments, indicating that P addition enhanced litterfall production. The monthly litterfall in all treatments showed similar seasonal patterns, with two peaks occurring in April to May and in November. Within litterfall components, foliar litter accounted for 53.78%-58.84%, sexual organs and miscellaneous accounted for 28.29%-33.66%, and branch accounted for 10.79%-12.87%. Results from this study demonstrated that high N treatment could result in excess N and imbalance of N and P in soils.

Key words: Changbai Mountains, litter mixing effect, litter decomposition, early frost period, benthic macroinvertebrate