封育对荒漠草原优势植物根系性状特征的影响

Effects of grazing exclusion on root trait characteristics of dominant plants in the desert steppe

研究植物根系特征变化对进一步了解禁牧封育过程中的植被变化具有重要意义。以宁夏荒漠草原不同封育年限(0、3、7和15年)下短花针茅(Stipa breviliora)、沙芦草(Agropyron mongolicum)、牛枝子(Lespedeza potaninii)、甘草(Glycyrrhiza uralensis)4种优势植物为研究对象,研究了封育对优势植物根性状特征的影响及其与植物地上部和土壤特性的关系。结果表明:1)封育措施下不同植物根性状变化不尽相同,短花针茅根表面积、平均根直径和根总体积封育后显著降低(P<0.05),比根长、比根面积在封育7年时最高;沙芦草的总根长、根表面积在封育3年时最高;封育对牛枝子、甘草的根系性状影响不显著。2)牛枝子0-40 cm地下生物量以封育3年最高,沙芦草、甘草地下生物量在封育7年最高;封育使深层根系生物量增加,短花针茅和沙芦草的30-40 cm土层和甘草的10-20 cm土层根系生物量在封育7年时最高。3)相关分析表明,荒漠草原植物根系受土壤有机质、碱解氮及土壤容重的影响明显,根系性状与植被盖度和地上生物量显著正相关(P<0.05)。研究认为,封育在一定程度改善了荒漠草原植物根性状,但不同植物变化不一,单一的封育措施短期内较难取得显著成效,需结合其他措施以加速植被恢复进程。

Examining the changes in plant root system characteristics is of great significance to further understanding vegetation changes during grazing exclusion.In this study,four dominant plants,Stipa breviliora,Agropyron mongolicum,Lespedeza potaninii and Glycyrrhiza uralensis,were studied under different grazing exclusion times(0,3,7,and 15 years)in Ningxia desert grassland.The effects of grazing exclusion on plant root characteristics and the association of aboveground plants and soil characteristics with root traits were analyzed.The results showed that:1)Root traits of different plants varied under grazing exclusion.The root surface area,average root diameter,and total root volume of S.breviflora decreased significantly with the extension of the grazing exclusion period(P<0.05),and its specific root length and specific root area were the highest after 7 years of grazing exclusion.The total root length and root surface area of A.mongolicum were the highest after 3 years of grazing exclusion.The effect of grazing exclusion on the root traits of L.potaninii and G.uralensis was not significant.2)The underground biomass of L.potaninii at 0-40 cm was the highest after 3 years of grazing exclusion,and that of A.mongolicum and G.uralensis was the highest in grassland with grazing exclusion for 7 years.The root biomass of S.breviliora and A.mongolicum in the 30-40 cm soil layer and G.uralensis in the 10-20 cm soil layer was the highest after 7 years of grazing exclusion.3)Correlation analysis demonstrated that soil organic matter,available nitrogen,and soil bulk density significantly affected plant roots in the desert steppe.Root traits had a significant positive correlation with vegetation coverage and aboveground biomass(P<0.05).In conclusion,grazing exclusion improved plant root traits in desert steppe to a certain extent.However,the effects observed in different plants varied.As it was difficult for a single grazing exclusion measure to achieve notable effects in the short term,grazing exclusion was combined with other measures to speed up the vegetation restoration process.