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滨海盐碱地生物土壤结皮对维管植物影响研究,鲜见报道.本研究旨在探讨黄河三角洲滨海盐碱地镶嵌式分布的生物土壤结皮是否以及如何影响两种典型草本植物的种子萌发,以深入理解基质异质性对植物群落动态的影响.通过室内萌发实验,研究裸斑、芦苇(Phragmites australis)、碱蓬(Suaeda glauca)和柽柳(Tamarvx chinensis)生境下发育的生物土壤结皮和无结皮表土对多年生草本植物芦苇和一年生草本植物碱蓬种子的萌发率和平均萌发时间的影响,并从基质理化性质角度探讨其对种子萌发的影响机制.研究结果发现,与无结皮表土相比,生物土壤结皮提高了含水量、养分积累和大部分盐离子浓度,但降低了土壤pH值.苔藓生物结皮可直接降低土壤pH值和Mg2+浓度,间接提高碱蓬种子的萌发率.较低的土壤pH值也间接降低了芦苇种子在其自身生境中的萌发速度.与有植被生长的生境相比,裸斑生境加剧Cl-的积累,间接降低了芦苇种子的萌发速度.结果表明,芦苇生境分布的苔藓结皮为碱蓬种子的萌发提供了一个机会窗口.生物土壤结皮类型和生境类型的共同作用可通过影响维管植物种子的萌发和建植,最终影响植物群落结构.“,”Aims The effects of biocrusts on vascular plants are rarely evaluated in coastal saline lands.Our aim was to examine whether and how a mosaic of biocrusts affect seed germination of two typical herbaceous plants in a coastal saline land of the Yellow River Delta,to enhance our understanding by which substrate heterogeneity influences plant community dynamics.Methods We conducted growth chamber experiments to investigate the effects of biocrusts and uncrusted soil from bare patch-,Phragmites australis-,Suaeda glauca-and Tamarix chinensis-dominated habitats on seed germination percentage and mean germination time of two herbaceous plants:the perennial P australis and the annual S.glauca.We also explored the mechanisms underlying the effects of substrate on seed germination.Important Findings Compared with uncrusted soil,biocrusts increased water content,nutrient accumulation and concentration of most salt ions,but they reduced soil pH value.Biocrusts with mosses directly decreased soil pH value and concentration of Mg2+,resulting in an indirect increase in seed germination percentage of S.glaucas.The low soil pH value also resulted in an indirect decrease in seed germination speed of P.australis in their own habitats.Bare patch directly increased accumulation of Cl-,resulting in an indirect decrease in seed germination speed of P.australis.These results suggest that biocrusts with mosses in P.australis habitats offer a window of opportunity for germination of S.glaucas.Biocrusts combined with habitat type have the potential to influence plant community structure through an effect on seed germination and establishment.