祁连山海北高寒湿地植物群落结构及生态特征

Plant Community Structure and Ecological Characteristics of the Alpine Wetland in Haibei Area of Qilian Mountains

海北高寒湿地系沼泽型和湖泊型湿地相并存．海北高寒湿地植物种类组成较少，从湿地中央到边缘植物优势种组成不同，群落结构变化明显．中部以帕米尔苔草为主要植物建群种的沼泽草甸，边缘地带以藏嵩草为主要建群种的沼泽化草甸，从中央到边缘地带主要有25种植物组成，隶属10科20属．高寒湿地植物有较高的地上生物量（349．373g·m^-2）和地下生物量（仅1～40cm层次最高可达10769．301g·m^-2），而且地下部分远高于地上部分，地下生物量从表层到深层基本均匀下降，与矮嵩草草甸和金露梅灌丛草甸区的地下生物量分布截然不同．因湿地帕米尔苔草、藏嵩草、黑褐苔草、华扁穗草等为主的植物粗纤维高，牲畜利用率下降，不论地上还是地下对土壤有机物的补给均较高，多年的积累使其海北高寒湿地有深达2～3m的泥炭层，使湿地形成一个非常重要的碳库．在气候变暖的条件下，这些未分解或半分解的土壤有机物质（或残体）将加速分解，对大气有更多的CO2、CH4等温室气体的排放．

Both swampy and lacustrine wetlands coexist in the Haibei area of the Qilian Mountains. There is few plant species in the plant community of alpine wetland in the Haibei area. From center to fringe of the wetland there is a significant difference in dominate species and the structure of plant community changes obviously. There are Carex pachyrrhiza meadow dominated by Carex pamirensis at the center area, and Kobresia tibetica meadow dominated by Kobresia tibetica distributed at the fringe area. There are 25 species （of 10 families and 20 categories） from the center area to the fringe. Both aboveground （349. 373 g ·m^-2） and belowground have higher biomass （10769. 301g· m^-2 just from 1 to 40 cm）, and belowground biomass is higher than that of aboveground. The belowground biomass decreases almost equally from surface to deep. Alpine meadow is significantly different from Kobresia humilis meadow and Potentilla fruticosa shrub. The proceeds ration to livestock is low for higher crude fibre content in some wetland plants such as Carex pamiroalaica, Kobresia tibetica, Carex alrofusca, and Blysmus sinocompressus. Due to the higher replenishment to soil organic matter both by aboveground and belowground, there appears a turf level, 2～3 m deep, in the alpine wetland in the Haibei area, after many years accumulation. Alpine wetland is an important carbon sink. The decomposition of all the half-decomposed and no-decomposed soil organic matter will accelerate as the climate warming, and more greenhouse gases such as carbon dioxide and methane release.