滨海湿地生态系统工程师对潮间带土壤环境的影响机制

在气候变化背景下,人类活动加剧了黄河三角洲盐沼湿地的退化进程,了解生态系统关键生物组成结构,尤其是生态系统工程师对环境塑造能力,对于开展基于生态系统关键生物过程的生态修复具有重要作用. 本文通过在黄河三角洲盐沼湿地进行野外现场观测和控制实验,研究了由天津厚蟹和日本大眼蟹主导的蟹类生态系统工程师的洞穴挖掘行为对潮滩地形地貌的影响,进而揭示地形地貌变化下的土壤理化指标差异性特征. 研究结果表明:蟹类挖掘洞穴的本能过程,是导致潮滩地形凹凸不平、地貌空间异质性的重要因素;经过蟹类挖掘松动后的穴居区域,土壤硬度和盐度显著降低,水土质量比增加. 蟹类的挖掘能够形成正反馈效应,改变了地形地貌,改善了土壤理化指标,有利于吸引更多的蟹类打洞、定居,进而促进洞穴挖掘面积的扩张. 本研究也表明人为模拟生态系统工程师过程,改变潮滩地形地貌特征, 构建凹凸不平的微地形地貌单元,能够起到改善土壤质地的作用,因此对开展基于生态系统过程的生态修复具有重要指示意义. 

Impact of ecosystem engineers on intertidal edaphic environment in coastal wetland:mechanisms involved

Human activities aggravate climate change-induced degradation of salt marsh in the Yellow River Delta.Understanding the natural ecosystem,especially ecosystem engineers shaping the environment,is important for ecological restoration.Field investigation and field control experiments in the Yellow River Delta were done in the present work to explore how ecosystem engineers (crab-burrowing activity)impact on intertidal geomorphological processes and edaphic environment in the coastal wetland.Crab-burrowing activity was found to be a key factor for concave-convex micro-topography and geomorphology spatial heterogeneity. Compared to flat microtopography without crab burrows,soil hardness and soil salinity in crab-burrowing concave-convex micro-topography were found to be significantly lower,soil moisture content in concave-convex micro-topography was significantly higher. Combined with field simulation experiment, changing micro-topography and physicochemical indicators made by crab-burrowing could make positive feedback effect for crab-burrowing activity.Artificial simulating ecosystem engineer process can also change geomorphological features of tidal flats,and improving edaphic environment for crabs to live,consequently making scientific and effective guidance for restoration of coastal salt marsh.