研究对比了年轻阔叶林和古老泛滥平原森林中落叶分解速率和8个月期间微生物生物量氮的变化。落叶分解在春季和秋季最快，观察结束时，两种森林中原始落叶剩余量相似，约为60-70%。分解过程中，残留落叶的微生物生物量氮与分解损失的落叶质量呈正相关。落叶质量差异影响了分解速率和碳同位素组成的变化，但氮同位素信号在两种森林的落叶中保持相似趋势。土壤中δ13C和δ15N表现出深度依赖的增加，但其季节变化并未反映分解落叶的模式，暗示区域环境因素如土壤温度和降雨可能调节这些同位素的季节变化。
摘要：
In the present study, rates of litter decomposition and microbial biomass nitrogen were monitored over an 8-month period in a young broadleaf plantation (18 y) and in an old floodplain forest. Moreover, δ13C and δ15N temporal variations within soil profiles were evaluated at both sites. Rates of litter decomposition were higher in spring and autumn than in summer, in both forests. At the end of the observation period the percentage of original litter remaining was not statistically different between the young and the old forest and accounted for 60–70% of the original amount. Microbial biomass nitrogen in the remaining litter and the percentage of litter mass lost during decomposition were positively correlated. The difference in litter quality affected the decomposition rate and also the changes in carbon isotopic composition during the decomposition process. In contrast, 15N isotopic signatures showed a similar trend in the litter of the two forests irrespective of the litter quality. Although δ13Csoil and δ15Nsoil showed considerable temporal variation they increased with depth in the soils of both sites but their seasonal changes did not reflect those of the decomposing litter. Within the same soil horizon, both δ13C and δ15N showed similar seasonal trends in the soils of the two forests, suggesting the involvement of environmental factors acting at regional level, such as soil temperature and rainfall variations, in regulating seasonal δ13C and δ15N soil variations.
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