Effects Of Soil Coarsening On Physiological Growth And Population Ecological Characteristics Of Lespedeza Dahurica(Laxm.) Schindl

Soil coarsening is the malignant development of soil desertification,which will lead to the further weakening or loss of the original function of soil,and also lead to the change of the growth and reproduction characteristics of individual plants and even the whole vegetation community.In this paper,aiming at the phenomenon of continuous soil coarsening in Horqin area of northern China,we simulated the soil coarsening in Horqin sandy land,and studied the photosynthetic characteristics,population characteristics,community characteristics and their correlation of Lespedeza dahurica,the dominant species of grassland in Horqin area,In order to provide technical and theoretical support for the dynamic monitoring and management of grassland and the biological improvement,introduction and domestication of desertification land in Horqin area.The main results are as follows:(1)Under different Soil coarsening treatments,the net photosynthetic rate,the transpiration rate and stomatal conductance of Lespedeza dahurica were the highest in S30 Soil coarsening treatment,followed by S10 or SCK treatment;The change direction of intercellular CO₂concentration and net photosynthetic rate was opposite.In stable state,the intercellular CO₂concentration under S30 and S10 soil coarsening treatments was significantly lower than that under S50 and S70 soil coarsening treatments;The change trend of leaf temperature was consistent with that of air temperature,and increased with the increase of soil coarsening after 12:00 noon.(2)The increase of soil coarsening degree led to the change of plant dominance in the vegetation community,increased the important value of Lespedeza dahurica,increased the important value of Potentilla chinensis,decreased the important value of Leymus chinensis,and increased the important value of Carex duriuscula first and then decreased.At the population level,soil coarsening significantly reduced the individual size of Lespedeza dahurica,significantly reduced the plant height and biomass of Lespedeza dahurica at flowering and fruiting stages,and also decreased the plant height,coverage and dry matter content of Lespedeza dahurica at bud stage,fruiting stage and aboveground biomass,but not significantly,increased the population density of Lespedeza dahurica,increased the base coverage and dry matter content of Lespedeza dahurica and the coverage at bud stage and flowering stage.At the community level,soil coarsening significantly reduced the height of vegetation community at different phenological stages,the coverage of plant base,the coverage at bud stage and the content of dry matter,and reduced the coverage at flowering stage,the coverage at fruiting stage,the biomass per plant and the aboveground biomass.This paper has 13 pictures,5 tables and 123 references.