黄河三角洲自然湿地植被的特征及演化

Characters and successions of natural wetland vegetation in Yellow River Delta

在群落样方调查基础上对黄河三角洲自然湿地植被进行了分类、分布及演化研究。研究表明,黄河三角洲滨海湿地的自然湿地植被有2个植被亚型、7个群系、51个群丛,分盐生植被、水生植被和湿生植被3类。盐生植被、水生植被和湿生植被分别包括10、19和22个群丛类型。盐生植被和湿生植被的面积各约23万hm2,各占自然湿地总面积的44.76%,水生植被约7.83万hm2,占自然湿地总面积的10.48%。湿地植被的分布受距海远近、黄河河道摆动和人类活动的制约,盐生植被主要分布在三角洲外缘潮间带滩涂和潮上带外缘的微斜平地,湿生植被、水生植被主要分布在潮上带中上部的微斜平地、黄河入海河道2侧及古河道、决口扇形地间的河间洼地。受三角洲新生湿地不断形成等自然因素的影响,湿地植被发生顺行演替;受海岸侵蚀、黄河断流、风暴潮等自然灾害及人类活动的影响,湿地植被发生逆行演替和次生演替。湿地植被的顺行演替和次生演替使自然湿地的生态环境功能增强,逆行演替使自然湿地的生态环境功能减弱。

Based on the sampling surveys, the natural wetland vegetation in Yellow River Delta was investigated and analyzed in the aspects of its classification, distribution and evolution. The research results showed that the natural vegetation of natural coastal wetland in Yellow River Delta was composed by 2 vegetation sub-types, 7 formations and 51 associations, which could be classified into halarch vegetation, hydromorphic vegetation and hydrophilic vegetation. These 3 sort vegetations were formed by 10, 19 and 22 associations each. The acreage of halarch vegetation and hydrophilic vegetation was about 23×10^4 hm^2 each and each accounted for 44.76% of all natural wetland. The acreage of hydromorphic vegetation was about 7.83×10^4 hm^2 and accounted for 10.48% of all natural wetland. The distribution of natural wetland vegetation was restricted by the distance to the sea, the swing of Yellow River and human activities. The halarch vegetation distributes mainly at upper tideland and flat land of supratidal zone outer edge. The hydromorphic vegetation and hydrophilic vegetation distribute mainly at the flat land, the banks of the river mouth and the depression land of middle and upper supratidal zone. The progressive successions of natural wetland vegetation were influenced by the constant formation of newborn wetland in the delta, and the regressive and secondary successions of natural wetland vegetation were caused by coastal erosion, the Yellow River cutoff, storm surge and other natural disasters and human activities. The progressive successions above increased the eco-environmental functions of the natural wetland, while the regressive successions reduced the eco-environmental functions of the natural wetland.