草地管理理论与实践发展研究

介绍了世界草地管理学科的发展概况,分析了草地管理理论与实践的发展现状,指出了值得借鉴的世界畜牧业发达国家草地管理经验,并展望了草地管理研究的发展方向。

Grazing effects on the relationship between plant functional diversity and soil carbon sequestration regulated by livestock species

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.

Belowground Tritrophic Food Chain Modulates Soil Respiration in Grasslands

Edaphic biota significantly affects several essential ecological functions such as C-storage, nutrient turnover, and productivity.However, it is not completely understood how belowground animal contribution to these functions changes in grasslands subject to different land use types. A microcosm experiment was carried out to test the effect of a tritrophic food chain on CO_2 release from grassland soils. Soil was collected from three differently managed grassland systems(meadow, pasture, and mown pasture) located in three distinct German regions that cover a north-south gradient of approximately 500 km. The tritrophic food chain comprised natural edaphic microflora, nematodes, and predatory gamasid mites. The experimental design involved a full factorial combination of the presence and absence of nematodes and gamasid mites. Nematodes significantly increased the CO_2 emissions in most treatments,but the extent of this effect varied with land use type. The fact that grazing by nematodes stimulated the metabolic activity of the edaphic microflora over a wide range of grassland soils highlighted the critical impact of the microfauna on ecosystem services associated with soil organic matter dynamics. Gamasids slightly amplified the effect of nematodes on microbial metabolic activity,but only in the pastures. This effect was most probably due to the control of nematode abundance. The fact that gamasid addition also augmented the impact of environmental conditions on nematode-induced modulation of soil respiration highlighted the need for including land use differences while evaluating soil fauna contribution to soil processes. To conclude, the differential response of the investigated tritrophic food chain to different grassland management systems suggests that adverse effects of land use intensification on important soil processes such as atmospheric C-release could potentially be reduced by using management methods that preserve essential features of the belowground food web.