青藏高原高寒草甸有毒植物对土壤理化性质和土壤微生物丰度的影响

Effects of toxic plants on soil physicochemical properties and soil microbial abundance in an alpine meadow on the Qinghai-Tibetan Plateau

草地退化促进有毒植物迅速扩张,已对我国青藏高原高寒草甸植物群落多样性和生产力构成了严重威胁。已有研究表明,有毒植物入侵影响植物群落,但有毒植物对地下生物及生物过程的影响研究较少。本研究调查了在高寒草甸草地上生长的5种主要有毒植物[甘肃棘豆(Oxytropis kansuensis)、瑞香狼毒(Stellera chamaejasme)、披针叶黄华(Thermopsis lanceolata)、麻花艽(Gentiana straminea)、黄帚橐吾(Ligularia virgaurea)]对土壤特性和微生物丰度的影响,并将这些影响和无毒牧草[垂穗披碱草(Elymus nutans)]对土壤特性和微生物丰度的影响进行了比较。研究发现,与无毒牧草垂穗披碱草相比,除麻花艽以外,所有有毒植物均显著增加了土壤全碳、全氮和微生物生物量碳(P<0.05),但对土壤pH没有显著影响。此外,有毒植物对土壤细菌、氨氧化细菌和反硝化细菌丰度有显著影响(P<0.05),但对土壤真菌丰度没有影响。结果表明,青藏高原有毒植物的扩张对土壤特性和土壤微生物有显著的影响,并且这些影响可能对草地生产力产生显著影响。

The fast spread of toxic plants promoted by ongoing grassland degradation has become a serious threat to plant diversity and productivity in alpine meadows on the Qinghai-Tibetan Plateau(QTP)in China.The impacts of toxic plant invasions on plant community characteristics have been well defined,but studies into their effects on belowground organisms and processes are rare.In this study,we investigated the effects of five dominant toxic plants growing in an alpine meadow grassland on the QTP(Oxytropis kansuensis,Stellera chamaejasme,Thermopsis lanceolata,Gentiana straminea,and Ligularia virgaurea)on soil parameters and microbial abundance.We also compared these effects with a non-toxic forage grass Elymus nutans.The results indicated that,compared to E.nutans,all toxic plants tested,except G.straminea,significantly increased total soil carbon,total soil nitrogen,and microbial biomass carbon(P<0.05).The soil pH was not effected by plant species.The toxic plants tested in this study had significant effects on the abundance of soil bacteria,ammonia oxidizing bacteria,and denitrifying bacteria(P<0.05),whereas the abundance of fungi was not affected by the toxic plants.These results indicated that the spread of toxic plants on the QTP could be of significant consequence to belowground soil properties,functions,and microorganisms,and they could have a significant effect on grassland productivity.