Species Distribution and Characteristics are Highly Related to Soil Salt Gradient in Songnen Plain

摘要

Soil salinization is a worldwide problem and around 954 million hectares of land are already salinized.Songnen grassland is an important product base of animals and crops.However,approximate 70％ of the nature grassland degraded due to improper land use,especially salt-alkalined problem.This research was carried out in Songnen meadow steppe to test how soil salt gradient can influence species distribution and characteristics during growth season(July-August 2009).Three representative heterogeneity patches with three lines were selected based on species appearance and proportion,each divided into different sections.Thus,the sites A and B were divided into three sections and the bottom section represented the center of site,the middle and top sections.The site C has been divided into four sections with two middle sections.The center part is defined as bottom section,where dominant species,and the middle and outer edge parts were defined as the middle and top sections,and dominant species were Chloris virgata,Phragmites communis,Leymus chinensis respectively.Our results showed salinity had significant effects on plant aboveground biomass,species relative biomass,solute organic content(chlorophyll and proline),soil nitrogen and soil organic matter.Aboveground biomass increased significantly from the bottom to top section(p≤0.05)and species appeared to benefit from interspecific neighbors.Kochia scoporia decreased significantly from section B by about 95％ to less than 20％ in section T.Chloris virgata,Phragmites communis,and Leymus chinensis increased by about 10％,5％,and 20％ from section B to more than 20％,80％ and 50％ in section T respectively.Kochia scoporia can survive at 90％ to high salinity.Chlorophyll and proline content increased proportionally to biomass,but did not seem to be related to salt stress in this study.Both soil nitrogen and soil organic matter increased significantly with the aboveground biomass increasing.In conclusion,plant organic solutes(e.g.chlorophyll and praline)are not related to species salt tolerance ability,other plant organic solutes,like carbohydrate and its components may be related to plant salt tolerance ability.Further study is needed to go to this direction.

目录

英文文摘

Introduction

Materials and Methods

Study areas

Sample collection

Measurements

Organic solutes(Chlorophyll a and chlorophyll b)

proline

pH and Electrical conductivity(EC)

Soil organic matter(SON)

Soil nitrogen

Data analysis

Results

Aboveground biomass

Relative biomass

Chlorophyll a and b

Proline content

Soil nitrogen

Soil organic matter

Soil electrical conductivity(EC)

Soil pH

Discussion

Conclusion

References

Acknowledgements

Curriculum vitae