Effects of mosaic biological soil crusts on vascular plant establishment in a coastal saline land of the Yellow River Delta, China

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.

Analysis of nutrient content and assessment of economic value for major salt-tolerant plants in coastal areas:a case study of Dongying City, Shandong Province

Salinization of soil is a worldwide problem concerning resources and ecology,especially serious in coastal areas.Testing of 26 sorts of data or parameters are carried out on leaves of 22 plant species(in 24 plant variety) of existing main salt-tolerant plant of the Yellow River Delta region.Data or parameters include the following ele-ments:contents of K+,Na+,Ca2+,Mg2+ and Cl-,contents of protein,fat,total energy,ash and contents of 17 amino acids.The results show that these tested plants have economic values.For example,according to their uses,they can be divided into edible plants,forage plants,medicine or health plants,and some of them can be used for multipurposes.These plants have played important roles in the sustainable utilization of plant resources in coastal areas.This paper has taken evaluations on the economic uses of salt-tolerant plants and given suggestions for saline soil improvement and resource utilization in coastal areas.Based on the results of investigation and experiments,we suppose that the salt-tolerant plants in coastal areas can be grouped into 9 main groups according to their economic value:pioneer plants for saline land improvement,medicine,edible and forage plants,industry material,forestation,breeding material,energy plants and eco-tourism resources.