Effect of sudden flow reduction on the decomposition of alder leaves (Alnus glutinosa [L.] Gaertn.) in a temperate lowland stream: a mesocosm study
Effect of sudden flow reduction on the decomposition of alder leaves (Alnus glutinosa [L.] Gaertn.) in a temperate lowland stream: a mesocosm study
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DOI：
10.1007/s10750-008-9694-4
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发表时间：
2009-02
期刊：
影响因子：
2.6
通讯作者：
J. Schlief;M. Mutz
中科院分区：
文献类型：
--
作者：
J. Schlief;M. Mutz
气候变化导致中欧低地河流夏季低流量和过早凋落物输入。这可能会导致流量突然减少，并分裂成永久流动的孤立溪流，同时在夏季增加觅食动物的食物供应。我们进行了一项中观研究，以调查碎纸机和微生物在这些条件下介导的凋落物分解。凋落叶被放置在具有自然流动状态的低地溪流（参考）和具有显著流量减少（FR）和大型无脊椎动物和碎屑的代表性密度的溪流中游环境中。每隔6周定期测量理化参数、叶片质量损失、大型无脊椎动物丰度和生物量、叶片相关呼吸、真菌产孢量和生物量。使用粗网袋和细网袋来包括或排除大型无脊椎动物碎纸机。在粗网目袋中，FR体系的叶片质量损失显著低于对照体系。在细孔袋中，随着流量的减少，叶呼吸、真菌孢子量和生物量显著降低，但叶质量损失没有显著降低。细网眼袋内的碎叶虫幼虫能有效地粉碎凋落叶。在FR体系中，粗网袋的叶片呼吸速率高于细网袋。我们的研究结果表明，在温带低地溪流中，在突然破碎成孤立池期间或之后的过早凋落物输入和溪流流量的减少减少了碎纸机直接调节的凋落物分解，但碎纸机可能间接影响分解过程。
Climate change leads to summer low flow conditions and premature litter input in lowland streams in Central Europe. This may cause a sudden reduction of flow and fragmentation into isolated pools of permanently flowing streams, with a simultaneous increase in the food supply for detrivores during summer months. We performed a mesocosm study to investigate shredder and microbial mediated litter decomposition under these conditions. Leaf litter was placed in a lowland stream with a natural flow regime (reference) and in a stream mesocosm with significant flow reduction (FR) and a representative density of macroinvertebrates and detritus. Physicochemical parameters, leaf mass loss, macroinvertebrate abundance and biomass, leaf-associated respiration, fungal sporulation, and biomass were measured at regular intervals for 6 weeks. Coarse and fine-mesh bags were used to include or exclude macroinvertebrate shredders. In the coarse-mesh bags, leaf mass loss was significantly lower in the FR system than in the reference regime. In the fine-mesh bags, leaf respiration, fungal sporulation, and biomass but not leaf mass losses were substantially lower with flow reduction. Chironomid larvae (Micropsectraspp.) appeared to effectively fragment leaf litter in fine-mesh bags. In the FR system, leaf respiration was higher in the coarse-than in the fine-mesh bags. Our results suggest that, in temperate lowland streams, premature litter input during or after a sudden fragmentation into isolated pools and a reduction of stream flow reduces direct shredder-mediated litter decomposition, but shredders may indirectly influence the decomposition process.