北京汉石桥湿地自然保护区植被分类与2003～2006年植被格局变化

Vegetation Classification and the Change of Vegetation Pattern from 2003 to 2006 in the Hanshiqiao Wetland Nature Reserve,Beijing

采用样线法结合样方法对北京汉石桥湿地自然保护区的湿地植被进行调查和分类研究。汉石桥湿地共有湿地植被2个植被型组、4个植被型、22个群系组、31个群系。对研究区主要植物群系进行多样性分析发现,莲(Nelumbo nucifera)群系的Simpson多样性指数最高,而芦苇(Phragmites australis)群系的Shannon-Wiener多样性指数和群系物种数最高。并对该湿地核心区2003年和2006年的主要湿地植被分布情况进行分析,结果表明,该湿地在2004年进行恢复工程的前后各区域土地利用和植被分布有较大变化,人为干扰及恢复工程是汉石桥湿地植被的分布变化的主要原因。针对目前的状况,保护区应该采取保障水源,营造不同的生境类型和保护湿地动植物资源等方法,维持湿地物种多样性和生态功能的稳定。

Hanshiqiao wetland Nature Reserve （40°07′N, 116°42′E） is located in the southwest of Yangzhen, a small town in Shunyi District, Beijing. Its area is 1 900 hm^2. The core zone takes up 8.61% of the wetland nature reserve, with the area of 163.5 hm^2. It can be divided zone into 3 districts： the big reed pond（distrlct Ⅰ ） , the east pond （district Ⅱ ） and the west pond （district Ⅲ ） according to its landform. To study the vegetation classification of the Hanshiqiao Wetland Nature Reserve, belt transect method and sample method were used. 69 families, 191 generaes,292 species were found in the wetland, and the vegetation can be divided into 2 groups of vegetation type, 4 vegetation types,22 groups of formation and 31 formations according to its formation character. When the formation diversity were studied, it indicated that the Simpson diversity index of Nelumbo nucifera formation was the highest , the Phragmites australis formation has the highest Shanno - Wiener diversity index and the species number in the formation. The land use and the vegetation distribution in 2003 and 2006 were compared and the vegetation distribution maps of that two years were made. A restoration project was made in the big reed pond in 2004, the channel was dug deeper, and a bird island and a bird seeing island were built. The water surface increased from 5. 660 hm^2 into 22.558 hm^2, and the reed formation increased from 83. 231 hm^2 into 94. 207 hm^2. At the same time, the xerophil community decreased in area from 28. 089 hm^2 into 5. 829 hm^2, and the farmland retreated from the big reed pond. The wetland restoration project played an important role in protecting the vegetation ecological function and maintaining the wetland ecosystem structure, but some submersed and emergent species disappeared during the project process. Lacking effective management and awareness of protecting the wetland, the east pond changed in function and usage in 2005. The area of water surface, Tyrha angustifolia formation and Scirpus caniculmis formation decreased. The crops, Nelumbo nucifera and Zizania aquatica, were planted and they almost occupied the whole area of the east pond. This change simplified the structure of that marsh ecosystem, and it would be hard to maintain the stabilization of ecosystem function and attract the birds to stay here. The west pond was protected by cutting off the afflux of polluted water. Before 2002, there was no plant here because it was hardly polluted by the pig farm next to the wetland. In 2003, when the pollution reduced, some plant grew. The dominant species were Polygonum caespitosum, Cypeus glomeratus, Pycreus globosus and Echinochloa crusgallii. In 2004, the water supplies increased and Nelumbo nucifera were planted, so the dominant species changed into Nelumbo nucifera, Glycine soja and Tyrha angustifolia. The wetland function became more steady and the migrate birds always took here as rest place. It indicated that the main reasons which lead to the changes of vegetation distribution are the human disturbance and the restoration project in 2004, and the conservation advises were given acording to the status of the Hanshiqiao wetland.