黄河三角洲典型潮沟系统水文连通特征及其生态效应

Hydrological connectivity characteristics and ecological effects of a typical tidal channel system in the Yellow River Delta

滨海盐沼湿地处于海陆交替的过渡区域,初级生产力高,是很多重要物种的栖息地,对于维持滨海湿地的功能及全球生态平衡起着重要的作用.在气候变化及人类活动的作用下,滨海盐沼湿地从结构完整性到生态功能的发挥都受到深刻影响.潮沟系统水文连通是滨海湿地的关键生态过程,同时也是维护和修复滨海湿地的重要途径.本文通过对黄河三角洲滨海盐沼湿地中一条典型、完整且具有主次支流的潮沟系统进行野外调查及原位观测,分析其水文连通特征及不同水文连通梯度下的土壤及生物空间分布规律.结果表明:水文连通强度受潮沟形态及地形地貌特征影响,其中淹水频次、累计淹水时长与潮沟形态及地形地貌特征具有显著的相关关系;土壤水盐特征受水文连通强度影响显著,水土质量比在大潮期大于小潮期,高频淹水区大于低频淹水区,而土壤盐度受淹水频次影响较大,较为频繁的淹水有助于缓解土壤盐度胁迫;盐地碱蓬生物量随水文连通梯度的分布规律与种子流通量、土壤种子库密度基本一致,均为高频淹水区大于低频淹水区,表明盐地碱蓬的分布主要取决于植物生命周期的各个过程对水文连通特征的适应性.

Salt marsh,transitional area between land and sea with high primary productivity,provides habitat for many important species,and plays important roles in maintaining the function of wetland and global ecological balance.The structure and ecological functions of salt marsh are greatly influenced by climate changes and human activities.Hydrological connectivity of tidal channel is a key ecological process for coastal wetlands,and is important for maintainence and repairment.In the present work,we investigated a typical tidal channel system with major and minor tributaries in the Yellow River Delta.Characteristics of hydrological connectivity and distribution of soil and biological characteristics under different gradients of hydrological connectivity were analyzed.Intensity of hydrological connectivity was found to be affected by the shape of tidal channel and topography.The frequency of flooding and cumulative duration of flooding was found to be significantly correlated with topography and shape of tidal channel.Soil moisture content and salinity were affected significantly by strength of hydrological connectivity.Moisture content in spring tide was greater than neap tide.Area of high flooding frequency was greater than low frequency.Soil salinity was found to be greatly influenced by flooding frequency.More frequent flooding helps alleviate salinity stress.Distribution of Suaeda salsa biomass along gradient of hydrological connectivity was consistent with seed flow and density of soil seed bank,high frequency flooding area was greater than low frequency flooding area.It is concluded that Suaeda salsa distribution mainly depends on adaptability of plant life cycle to features of hydrological connectivity.