摘要
Grazing exerts a profound influence on both the plant diversity and productivity of grasslands,while simultaneously exerting a significant impact on regulating grassland soil carbon sequestration.Moreover,besides altering the taxonomic diversity of plant communities,grazing can also affect their diversity of functional traits.However,we still poorly understand how grazing modifies the relationship between plant functional diversity(FD)and soil carbon sequestration in grassland ecosystems.Here,we conducted a grazing manipulation experiment to investigate the effects of different grazing regimes(no grazing,sheep grazing(SG)and cattle grazing(CG))on the relationships between plant FD and soil carbon sequestration in meadow and desert steppe.Our findings showed that different livestock species changed the relationships between plant FD and soil organic carbon(SOC)in the meadow steppe.SG decoupled the originally positive relationship between FD and SOC,whereas CG changed the relationship from positive to negative.In the desert steppe,both SG and CG strengthened the positive relationship between FD and SOC.Our study illuminates the considerable impact of livestock species on the intricate mechanisms of soil carbon sequestration,primarily mediated through the modulation of various measures of functional trait diversity.In ungrazed meadows and grazed deserts,maintaining high plant FD is conducive to soil carbon sequestration,whereas in grazed meadows and ungrazed deserts,this relationship may disappear or even reverse.By measuring the traits and controlling the grazing activities,we can accurately predict the carbon sequestration potential in grassland ecosystems.
放牧对草地的植物多样性与生产力都具有深远影响,同时对调节草地功能固碳也有重要影响。此外,放牧除了会改变植物群落的分类多样性,还会影响其功能性状多样性。然而,放牧对草地生态系统植物功能多样性与土壤固碳之间关系的影响尚不清楚。因此,我们进行了控制放牧实验,研究不同放牧制度(无牧、羊放牧和牛放牧)对草甸草原和荒漠草原植物功能多样性与土壤固碳功能之间关系的影响。研究结果表明,不同家畜物种改变了草甸草原植物功能多样性与土壤有机碳(SOC)之间的关系。羊放牧使植物功能多样性与土壤有机碳的正相关关系解耦,而牛放牧则使两者之间的关系由正变负。在荒漠草原,羊放牧与牛放牧均能加强植物功能多样性与土壤有机碳之间的正相关关系。我们的研究阐明了家畜物种对土壤固碳复杂机制的巨大影响,这种影响主要是通过调节植物功能性状多样性来实现的。在未放牧的草甸草原和放牧的荒漠草原中,保持较高的植物功能多样性有利于土壤固碳,而在放牧的草甸草原和未放牧的荒漠草原中,这种关系可能消失甚至逆转。通过测量植物功能性状和控制放牧家畜物种,我们可以更准确地预测草地生态系统的固碳潜力。
基金
supported by the National Natural Science Foundation of China(31772652 and 31802113)
China Scholarship Council(202006620065)。
