Zhang Ya-Lin, Zhang Wei-Jun, Duan Jun-Peng, Pan Xu, Liu Guo-Fang, Hu Yu-Kun, Li Wen-Bing, Jiang Yue-Ping, Liu Jian, Dai Wen-Hong, Song Yao-Bin, Dong Ming
Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, College of Life and Environmental Sciences Hangzhou Normal University Hangzhou China.
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany Chinese Academy of Sciences Beijing China.
Ecol Evol. 2019 Jul 31;9(16):9376-9384. doi: 10.1002/ece3.5488. eCollection 2019 Aug.
Allochthonous (e.g., riparian) plant litter is among the organic matter resources that are important for wetland ecosystems. A compact canopy of free-floating vegetation on the water surface may allow for riparian litter to remain on it for a period of time before sinking to the bottom. Thus, we hypothesized that canopy of free-floating vegetation may slow decomposition processes in wetlands. To test the hypothesis that the retention of riparian leaf litter on the free-floating vegetation in wetlands affects their subsequent decomposition on the bottom of wetlands, a 50-day in situ decomposition experiment was performed in a wetland pond in subtropical China, in which litter bags of single species with fine (0.5 mm) or coarse (2.0 mm) mesh sizes were placed on free-floating vegetation (dominated by , , and ) for 25 days and then moved to the pond bottom for another 25 days or remained on the pond bottom for 50 days. The leaf litter was collected from three riparian species, that is, , , and . The retention of riparian leaf litter on free-floating vegetation had significant negative effect on the carbon loss, marginal negative effects on the mass loss, and no effect on the nitrogen loss from leaf litter, partially supporting the hypothesis. Similarly, the mass and carbon losses from leaf litter decomposing on the pond bottom for the first 25 days of the experiment were greater than those from the litter decomposing on free-floating vegetation. Our results highlight that in wetlands, free-floating vegetation could play a vital role in litter decomposition, which is linked to the regulation of nutrient cycling in ecosystems.
外来（如河岸带）植物凋落物是对湿地生态系统很重要的有机物质资源之一。水面上紧密的漂浮植被冠层可能会使河岸带凋落物在沉入水底之前在其表面停留一段时间。因此，我们推测漂浮植被冠层可能会减缓湿地中的分解过程。为了验证湿地中河岸带树叶凋落物在漂浮植被上的留存会影响其随后在湿地底部的分解这一假设，在中国亚热带地区的一个湿地池塘中进行了一项为期50天的原位分解实验，将具有细（0.5毫米）或粗（2.0毫米）网眼尺寸的单一物种凋落物袋放置在漂浮植被（以、和为主）上25天，然后移至池塘底部再放置25天，或者一直留在池塘底部50天。树叶凋落物取自三种河岸带物种，即、和。河岸带树叶凋落物在漂浮植被上的留存对碳损失有显著负面影响，对质量损失有轻微负面影响，对树叶凋落物的氮损失没有影响，部分支持了该假设。同样，在实验的前25天里，在池塘底部分解的树叶凋落物的质量和碳损失大于在漂浮植被上分解的凋落物。我们的结果表明，在湿地中，漂浮植被在凋落物分解中可能起着至关重要的作用，这与生态系统中养分循环的调节有关。
