天津厚蟹植食对黄河三角洲高潮滩芦苇幼苗生长的影响

The effects of crab herbivory on the growth of Phragmites australis seedlings in a high marsh of the Yellow River delta

上行因子、下行因子和种内种间作用均会影响盐沼植物的生长繁殖,然而上行效应的研究较多,而下行效应的研究则较少。芦苇(Phragmites australis)是黄河三角洲湿地的主要植被类型,而潮水芦苇则是重要和独特的芦苇种群。本研究旨在探讨下行效应对黄河三角洲潮水芦苇幼苗生长的影响。本研究于芦苇幼苗期在黄河三角洲自然保护区潮水芦苇区域设置24个2 m×2 m样方调查天津厚蟹取食对芦苇幼苗生长的影响。结果表明:潮水芦苇幼苗受了天津厚蟹的严重取食和破坏;24个样方中共有1139株芦苇幼苗,其中被轻度取食的芦苇幼苗有308株(占27.04%),被重度取食的芦苇幼苗有234株(占20.54%),未被取食的芦苇幼苗有597株(占52.41%);黄河三角洲潮水芦苇幼苗生长指标受到天津厚蟹取食的显著影响,天津厚蟹重度取食显著减少芦苇幼苗高度生长、减少幼苗叶片数和幼苗叶片长度。因此,在黄河三角洲潮水芦苇保护和管理时应该考虑下行因子对芦苇生长的影响。

Bottom-up and top-down effects as well as intra and inter specific interactions drive plant growth and reproduction in the salt marsh. Compared to the bottom-up effect, however, the top-down effect has been largely overlooked. Phragmites australis is a dominant species, whose populations living in the high marsh are important and unique in the Yellow River Delta. To reveal the impacts of the top-down factor on the growth ofP. australisseedlings in the high marsh, we investigated the effects ofHelice tientsinensis herbivory on their growth by establishing 24 plots with a size of 2 m×2 m. The seedlings ofP. australis were heavily grazed and damaged by crab. In all plots, 52.41% of seedlings were not consumed by crabs, 27.04% of seedlings were mildly fed, and heavy herbivory by crab accounted for 20.54%. The growth of seedlings was significantly influenced by crab herbivory. Heavy herbivory by crab strongly reduced the height, leaf number and leaf length of seedlings. The top-down effects should be considered in the protection and management of P. australis vegetation in the Yellow River Delta.