人工湿地3种植物凋落物分解及其对水位降低的响应

为了解人工湿地种植的3种植物凋落物分解特征，采用网袋法，通过1 a的凋落物分解实验，研究了人工湿地3种植物(美人蕉、狭叶香蒲和梭鱼草)凋落物储量、凋落物分解动态及其对水位降低的响应.结果表明：美人蕉、狭叶香蒲和梭鱼草3种植物凋落物储量分别为1 887.83、1 073.25、2 358.86 g·m－2；分解1 a后，3种凋落物年分解率各自为63.5%、46.5%、61.1%，且它们之间存在差异显著(p<0.05).通过Olson 经典指数模型拟合的3种凋落物分解方程，表明了美人蕉凋落物分解速率最高(k＝0.063)，其次为梭鱼草(k＝0.047)，最小为狭叶香蒲(k＝0.032)；湿地植物立枯期间，模拟3种植物美人蕉、狭叶香蒲、梭鱼草的枯落物(叶)在立枯期间的分解速率比枯落物死亡后放置地表的分解速率各自减少6.9%、8.6%和6.9%.人工湿地岸带，水位降低，美人蕉、狭叶香蒲、梭鱼草3种植物凋落物的分解速率分别较水淹条件下增加了33.8%、42.5%和69.6%.这些结果表明气候变暖，可能降低湿地岸带水位，进而增强湿地碳释放.

Decomposition of three plant litter types in the constructed wetland and its response to water table draw-down

To understand the decomposition of three plants litter types in constructed wetland， the litter decomposition was studied by using the mesh bag method during one year. The storage， decomposition dynamics， and its response to water table drawdown from three plants litter types (Canna indica， Typha angustifolia， and Pontederia cordata) were investigated in the constructed wetland in suburban Wuhan City. This results showed that the litter storage of the Canna indica， Typha angustifolia， and Pontederia cordata were 1 887.83， 1 073.25， and 2 358.86 g·m-2， respectively. During one year， there were significantly different in decomposition rate among three litter types (p<0.05)， and their decomposition rate were 63.5% for Canna indica， 46.5% for Typha angustifolia， and 61.1% for Pontederia cordata， respectively. In addition， the Olson classical exponential model showed that the litter decomposition rate of Canna indica (k＝0.063) was highest， followed by Pontederia cordata (k＝0.047)， and Typha angustifolia (k＝0.032). During standing litter， the leaf decomposition rate in the constructed wetland was 6.9%， 8.6%， and 6.9% lower than that on the surface， for Canna indica， Typha angustifolia， and Pontederia cordata， respectively. With the water table draw-down， the litter decomposition rate from the Canna indica， Typha angustifolia， and Pontederia cordata have increased in the shore zone of wetlands by 33.8%， 42.5% and 69.6% compared with that in flooding zone， respectively. These results suggested that the warming climate might decrease the water table in the shore zone of wetlands， and then increase the carbon emission of the wetlands.