【作者】 肖翔溢；

【导师】 曾波；

【作者基本信息】 西南大学 ， 生态学， 2012， 硕士

【摘要】 消落带生态系统是水生生态系统和陆地生态系统交替控制的不稳定的特殊湿地生态系统。在人工调度下,由于三峡水库的水位涨落速度、幅度和频率与天然河道明显的不同,增加了消落带的不稳定性。该消落带出露时间较短,耐淹的草本植物是消落区最重要的植物类型。草本植物的淹没分解是水库生态系统物质循环和能量流动的重要环节,对水库底栖生物群落的营养结构产生显著影响。另一方面,植物体分解可能会造成水体的富营养化问题。植物释放营养盐的速率和对上覆水体水质的影响受到研究区域的水体条件和植物种类的影响较大。本研究通过测定不同五种耐淹植物(碚芦芒、地芒1号、马筋草5号、马筋草3号、铁跘草1号)在不同水淹条件下分解率的变化,旨在对这5个耐淹物种的分解是否会造成水体的二次污染提供先期的数据与理论依据。本实验研究内容包含三个方面：第一,三峡库区中段忠县境内的汝溪河流域内,5种耐淹植物物种在不同水淹高程中其离体部分植物体和非离体部分植物体分解率差异,以及不同水淹高程中植物体分解率的差异。第二,模拟三峡库区水淹的情况,研究水淹6个月内,不同水淹深度对实验物种分解率的影响,以及植物体茎段完整与否对实验物种分解率的影响。第三,模拟三峡库区水体流动造成的水体更换,研究水体更换与否对实验物种分解率的影响。针对以上三个方面的研究,结果分别表明：第一,在汝溪河岸,不同水淹深度对五个物种的分解率没有显著影响；同一高程离体样品的分解率显著高于非离体样品,因此植物体在水淹条件下死亡与存活的情况是影响消落区内植物体分解速率的重要因素。第二,五个物种的各个样品在第一个月中的每月分解率均大于其它5个月。因此在水淹植物的第一个月中应对库区水质进行严密监控,以避免二次污染的发生。水淹深度对植物的分解率的影响不大。植物体破碎对植物分解速率的影响因物种而异。其中,马筋草3号与马筋草5号断茎的分解率要显著高于其完整茎,但地芒1号和碚芦芒的断茎与完整茎、断叶与完整叶的分解率均没有明显差异。第三,定期换水与不换水对五种耐淹植物分解率的影响没有显著差异。更多还原

【Abstract】 Water level fluctuation zone is an unstable special wetland ecosystem formed by alternative change of aquatic ecosystem and terrestrial ecosystem. Difference between Three Gorges reservoir region and natural river in terms of water level fluctuating speed, amplitude and frequency due to the artificial scheduling of the Three Gorges reservoir, the instability of fluctuating zone there has been intensified. Since the fluctuating zone only exposes for a short term, submergence tolerant herbs are the most important plants in the drawdown area. Submerged decomposition of herbaceous plants is one key component element in material cycling and energy flow in the reservoir ecosystem, which makes a significant contribution to the trophic structure of reservoir benthic community. On the other hand, the decomposition of plants might cause water eutrophication. There will be great effects of water conditions and plant species in the study area on plant nutrient releasing rate and the quality of overlying water. Therefore, through examining the decomposition rate dynamics of five different submergence tolerant plants(Phragmites 3#, Miscanthus 1#, Graminoid 5#, Graminoid 3#, and Graminoid 1#) under water, our research aims to offer early data and theoretical foundation for determining their decomposition could cause secondary pollution to water body or not.Three aspects were included in our research. First, differences of decomposition rate of isolated part and non-isolated part of these five species under different flooding elevation were studied in field, as well as the differences among flooding elevations at Ru-xi catchment in Zhong County in the middle area of the Three Gorges reservoir region. Second, to simulate flooding situation in the Three Gorges reservoir region, impacts of different flooding depths on the decomposition rate of the experimental species, and the impacts of plant stem’s integrity on experimental species decomposition rate were researched in a six-month’s submergence. Last, the effects of flowing water and stagnant water on the decomposition rate of five experimental species were also explored in simulating the water flow rate change in the Three Gorges reservoir region.Through the above studies, results indicated that:i) Different flooding depth had no significant effects on decomposition rate of the five species in the river bank of Re-xi catchment. In the same elevation, decomposition rate of isolated samples was significantly higher than that of non-isolated parts. Thus, it was death and survival of plants in flooded conditions that have affected the decomposition rate of plants in hydro-fluctuation zone, ii) The monthly decomposition rate of the five species samples in the first month was higher than the other five months. Therefore, water quality should be closely monitored for the first month when plants are submerged, in order to prevent secondary pollution. In addition, flooding depth had little effect on the decomposition rate of plant. The effects of plant fragmentation on decomposition rate were differed with species. Specifically, the decomposition rate of broken stem of Graminoid 3# and Graminoid 5# were significantly higher than their complete stems respectively, whereas there was no significant difference between the decomposition rate of broken and complete stem, broken and complete leaf in terms of Miscanthus 1# and Phragmites 3# respectively, iii) No significant difference was found in the decomposition rate of these five submergence tolerant plants between regularly water change and no change of water, including the leaves and stems of Graminoid 5#, Graminoid 3#, Miscanthus 1# and Phragmites 3#, and the whole plant body of Graminoid 1#.更多还原