Impact of Desertification Severity on Astragalus bhotanensis in Population Dynamics in Reseeding Grassland
This study investigated the establishment and dominance of Astragalus bhotanensis in reseed-ing grasslands across varying desertification severity(non-sandy,mild,moderate,and severe desertifica-tion)within the western Sichuan Plateau.Astragalus bhotanensis,a local legume forage,was selected for its potential in grassland restoration.Population establishment metrics(germination,growth,and impor-tance value)were assessed.The results showed the following:1)The relative impact of desertification severity on each Astragalus bhotanensis population establishment indicator was ranked as follows:seedling rate＞emergence rate＞survival rate＞population density＞germination rate.Emergence rate,seedling rate,survival rate,and population density were significantly higher in sandy grasslands compared to non-desertified areas,with significant difference observed across different levels of desertification severity(P＜0.05).2)Desertification severity significantly affected the dominance index of Astragalus bhotanensis,ranked as follows:relative density＞important value＞relative coverage＞relative frequency.The relative frequency,coverage,and density of Astragalus bhotanensis increased significantly with increasing desertifi-cation severity(P＜0.05).Importancte value was significantly elevated in mildly,moderately,and severely desertified grasslands compared to non-desertified areas(3.56,10.96,and 17.26 times,respec-tively).3)The impacts of relative desertification on growth indicators were as follows:plant height＞branching number＞root to shoot ratio＞belowground allocation ratio＞aboveground biomass＞below-ground biomass＞upright degree.Plant height and upright degree decreased with increasing desertification severity,while branching number and belowground biomass increased(P＜0.05).Root to shoot ratio and belowground allocation ratio were higher in severely desertified areas.In summary,Astragalus bhotanensis exhibited strong adaptability to desertified conditions,demonstrating successful establishment and increased dominance with increasing desertification severity.This species holds potential for grassland res-toration in degraded areas.
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