补播乡土牧草对荒漠草地土壤持水性及植被生物量的影响

Effects of reseeded native forage species on soil water holding capacity and vegetation biomass in a desert steppe

为了探讨乡土牧草补播对退化草地植被恢复的作用,在宁夏盐池县设置了以放牧地(FM)为对照,以蒙古冰草(Agropyron mongolicum)单播(M)、牛枝子(Lespedeza potaninii)单播(N)、蒙古冰草+牛枝子混播(MN)、蒙古冰草+沙打旺(Astragalusadsurgens)混播(MS)和蒙古冰草+草木樨状黄芪(Astragalusmelilotoides)混播(MX)为补播模式,研究不同补播措施对荒漠草地土壤持水性及地上地下生物量的影响。结果表明:1)不同处理间土壤持水性的综合排序为M>MS>MN>MX>N>FM。2)所有补播处理的地下生物量均高于放牧草地,且单播牧草的地下生物量M高于N;而处理间地上生物量表现为MS>MX、M、MN>N>FM的趋势。3)冗余分析(RDA)结果表明,植被地下、地上生物量和表征土壤持水性的指标间显著相关(P<0.05)。本研究结果表明蒙古冰草由于具有较高的地下生物量,单播或与豆科混播均可以显著改善土壤持水性,进而利于植被的恢复,故而在未来草地补播中应因地制宜采用根系生物量大的牧草进行单播或与其他牧草混播。

To explore the impact of reseeded native species on vegetation restoration in degraded grasslands we assessed the effects of Agropyron mongolicum monoculture(M),Lespedeza potaninii monoculture(N),A.mongolicum×L.potaninii mixture(MN),A.mongolicum×Astragalus adsurgens mixture(MS),A.mongolicum×A.melilotoides mixture(MX),and grazing grassland(FM)on soil water holding capacity-related parameters,as well as aboveground and underground biomass in Yanchi County,Ningxia.The results showed that:1)Soil water holding capacity differed among different treatments(M>MS>MN>MX>N>FM).2)All reseeded treatments led to higher underground biomass than FM,and underground biomass was higher under M than N,while aboveground biomass varied according to MS>MX,M,MN>N>FM.3)Redundancy analysis(RDA)showed that underground and aboveground biomass were positively and significantly correlated with all the soil water holding capacity-related parameters.In conclusion,this study demonstrated that both monocultures,or mixed reseeding,of A.mongolicum could improve soil water holding capacity and accelerate vegetation restoration due to its high biomass.Therefore,plants with high biomasses should be considered in future restoration plans of degraded grassland.