Long-term grazing effects on soil greenhouse gases emission and soil microbial communities of Alberta grasslands

• Author / Creator

  Stolnikova, Ekaterina

• Grasslands cover a large area of the terrestrial surface and their soils store vast amounts of carbon (C) and nitrogen (N). Small changes in the processes driving C and N cycling can lead to either sequestration of these elements or their release as greenhouse gases (GHG) into the atmosphere. While livestock grazing is the primary use of grasslands worldwide, its effect on soil GHG fluxes and soil microbial communities remains unclear, especially in northern temperate grasslands. This thesis reports on the effect of long-term cattle grazing on soil GHG fluxes and soil microbial communities across the grasslands of Alberta, Canada (Central Parkland, CP; Dry Mixedgrass, MG; Foothills Fescue, FF subregions), over two growing seasons (2015 and 2016).
  Using static chambers and gas chromatography, the CO2, CH4 and N2O fluxes from soils were measured. Livestock grazing itself did not affect cumulative GHG fluxes in either year. However, the cumulative CO2 emission was altered by a grazing and year interaction, being relatively lower from grazed than non-grazed areas in the dry year, while the opposite was true during the wet year. Among subregions the lowest cumulative CO2 was observed within MG. The soil microbial communities (bacterial, archaeal and fungal) was quantitatively and qualitatively assessed using quantitative polymerase chain reaction and high-throughput sequencing. Livestock grazing did not affect the abundance of bacterial and archaeal communities, or richness and beta diversity in either year. However, fungal alpha diversity was lower in grazed areas during the dry year, but greater in the same areas during the wet year. Also, richness of bacterial and archaeal communities was greater within MG, while their abundance was greater within FF.
  Overall this study showed that light to moderate long-term grazing had limited impact on soil GHG fluxes and soil microbial communities, compared to non-grazed areas of the grasslands, while regional characteristics (climatic conditions) and soil properties had a greater impact.

• Subjects / Keywords

  • microorganisms
  • rangelands
  • carbon
  • nitrogen
  • cattle

• Graduation date

  Fall 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R33X8424M

• License

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