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.
Environ Sci Pollut Res Int. 2019 Mar;26(8):8248-8256. doi: 10.1007/s11356-019-04145-x. Epub 2019 Jan 30.
In wetland ecosystems, vegetation can float freely on water surface, forming dense canopy which may play important ecological roles. This is especially true in many urban wetlands in which fluidity is low and nutrient level is high. So far, effects of free-floating vegetation on abiotic and biotic factors of wetlands have been known, while little on wetland ecosystem functions such as litter decomposition. To examine whether the canopy of free-floating vegetation on water surface will influence litter decomposition in wetlands or not, we conducted a 50-day in situ decomposition experiment in a subtropical urban pond wetland, in which litter bags of nine combinations of three mesh sizes and three litter species were put on the bottoms of total 22 ponds which were half with and half without free-floating vegetation canopy on the water surface. The ponds with and without the canopy had different water physicochemical properties. Overall, the canopy, the species identity, and the mesh size significantly decelerated mass loss and carbon loss of leaf litters while slightly on nitrogen loss. Effects of the canopy on leaf litter decomposition also showed species- and mesh size-dependent. Our results suggest that free-floating vegetation on water surface can alter water environmental factors and consequently change ecosystem functioning in wetlands.
在湿地生态系统中，植被可以在水面上自由漂浮，形成茂密的树冠，这些树冠可能发挥着重要的生态作用。在许多城市湿地中，这种情况尤其如此，因为这些湿地的流动性较低，营养水平较高。到目前为止，人们已经了解了自由漂浮植被对湿地非生物和生物因素的影响，但对湿地生态系统功能（如凋落物分解）的影响却知之甚少。为了研究水面自由漂浮植被的树冠是否会影响湿地中的凋落物分解，我们在亚热带城市池塘湿地中进行了为期 50 天的原位分解实验，在其中的 22 个池塘底部放置了 9 种组合的三种网眼大小和三种凋落物的凋落物袋，其中一半池塘的水面上有自由漂浮的植被树冠，另一半没有。有和没有树冠的池塘具有不同的水理化性质。总的来说，树冠、物种身份和网眼大小显著减缓了叶片凋落物的质量损失和碳损失，但对氮损失的影响较小。树冠对叶片凋落物分解的影响也表现出物种和网眼大小依赖性。我们的结果表明，水面上的自由漂浮植被可以改变水生态环境因素，从而改变湿地的生态系统功能。
