基质类型和物种丰度对沉水植物模块化生长及根系发育的影响

Effects of sediment type and species abundance on modularization growth and root development of submerged macrophytes

沉水植物恢复是富营养化湖泊生态恢复的关键,基质类型和物种丰度对沉水植物生长和群落稳定具有重要作用,本研究旨在探索不同基质类型和物种丰度对沉水植物生长及根系发育的影响,为富营养化湖泊沉水植物恢复技术研究提供基质筛选和物种配置的技术参数。研究选取苦草(Vallisneria natans(Lour.)Hara)、微齿眼子菜(Potamogeton maackianus A.Bennett)、穗状狐尾藻(Myriophyllum spicatum L.)、伊乐藻(Elodea nuttallii(Planch.)H.St.John)4种沉水植物,根据物种丰度(1、2、3、4个物种)配置了11个物种组合,且选配了4种基质类型:无疏松层(a1、a2)和有疏松层(b1、b2),总计处理数为44(n=11×4)。测定了地上生物量、地下生物量、总生物量、株高、最大根长、总根长、总根表面积、总根体积、根平均直径、总根尖数、根分枝数、根交叉数、根冠比、根比表面积等14个生长及根系功能性状指标。结果表明:(1)随着沉水植物丰度的增加,地下生物量、总生物量、株高、最大根长、总根长、总根表面积、总根体积、总根尖数、根分枝数、根交叉数10个性状显著降低。(2)不同基质类型,总根表面积、总根尖数性状存在显著差异,有疏松层基质处理组功能性状显著高于无疏松层基质处理组。(3)穗状狐尾藻竞争能力在苦草+穗状狐尾藻、苦草+穗状狐尾藻+伊乐藻和苦草+微齿眼子菜+穗状狐尾藻+伊乐藻3个混种组合中混种时强于单种,苦草竞争能力在苦草+微齿眼子菜、苦草+穗状狐尾藻、苦草+伊乐藻、苦草+微齿眼子菜+穗状狐尾藻、苦草+微齿眼子菜+伊乐藻、苦草+穗状狐尾藻+伊乐藻和苦草+微齿眼子菜+穗状狐尾藻+伊乐藻7个混种组合中单种强于混种,微齿眼子菜在苦草+微齿眼子菜+穗状狐尾藻、苦草+微齿眼子菜+伊乐藻和苦草+微齿眼子菜+穗状狐尾藻+伊乐藻3个混种组合中单种时强于混种,伊乐藻无显著差异。本研究指出在富营养化湖泊沉水植物恢复技术研发中,修复工程早期沉水植物物种丰度配置1~2种较为适宜、基质中添加疏松层、先锋物种选择苦草和穗状狐尾藻更有利于沉水植物模块化生长及根系发育。

Submerged macrophyte restoration is the key to ecological restoration of eutrophic lakes.Sediment type and species abundance play an important role in the growth and community stability of submerged macrophytes.This study aimed to explore the effects of different sediments types and species abundance on the growth and root development of submerged macrophytes,and to provide technical parameters for sediment selection and species configuration for the study of submerged macrophyte restoration techniques in eutrophic lakes.The study selected Vallisneria natans(Lour.)Hara,Potamogeton maackianus A.Bennett,Myriophyllum spicatum L.,(Elodea nuttallii(Planch.)H.St.John),four submerged macrophytes,11 species combinations were configured according to species abundance(1,2,3,4 species),and four sediments types were selected:without lax layer(a1,a2)and with lax layer(b1,b2),for a total number of 44 treatments(n=11×4).Fourteen growth and root functional traits were measured:above ground biomass,below ground biomass,total biomass,shoot height,maximum root length,total root length,total root surface area,total root volume,average root diameter,total root tip number,number of root branch,number of root cross,root to crown ratio,and root specific surface area.The results showed that(1)the total biomass,below ground biomass,shoot height,maximum root length,total root length,total root surface area,total root volume,average root diameter,total root tip number,root branch number,and root cross number decreased significantly with the increase of submerged macrophyte abundance.(2)total root surface area and total root tip number,were significantly different between sediments types,and most of these traits were significantly higher in the sediment treatment with a lax layer than in the sediment treatment without a lax layer.(3)Among the seven mixed species combinations,M.spicatum competitive ability is stronger in mixed planting than in monoculture at V.natans+M.spicatum,V.natans+M.spicatum+E.nuttallii and V.natans+P.maackianus+M.spicatum+E.nuttallii three mixed combinations,and the competitive ability of V.natans was stronger monocultures than in mixed planting at V.natans+P.maackianus,V.natans+M.spicatum,V.natans+E.nuttallii,V.natans+P.maackianus+M.spicatum,V.natans+P.maackianus+E.nuttallii,V.natans+M.spicatum+E.nuttallii,V.natans+P.maackianus+M.spicatum+E.nuttallii seven mixed combinations,and P.maackianus was stronger monocultures than mixed planting in three mixed combinations,including V.natans+P.maackianus+M.spicatum,V.natans+P.maackianus+E.nuttallii and V.natans+P.maackianus+M.spicatum+E.nuttallii,no significant difference in E.nuttallii.Our study suggests that in the development of submerged macrophyte restoration technology for eutrophic lakes,monoculture submered macrophyte are more appropriate in the early stage of the restoration project,and highlights that lax substrate and the presence of V.natans and M.spicatum are beneficial to the growth and root development of submerged macrophyte communities.