Lat/Long

The rangeland studies were conducted near Cheyenne, Wyoming, on selected sites at the High Plains Grasslands Research Station (41.18 N, 104.88 W).

The Big Sky Carbon Sequestration Partnership (BSCSP) commissioned research on selected sites at the High Plains Grasslands Research Station (Cheyenne, Wyoming).

Why this Location

The northern mixed grass rangeland site near Cheyenne, Wyoming, is representative of much of the rangeland in the Big Sky Carbon Sequestration Partnership (BSCSP) region.

Main Research Q&As Discovered

Rangelands occupy approximately half of the world’s land area and store greater than 10% of the terrestrial biomass carbon and up to 30% of the global soil organic carbon (SOC). Although soil carbon storage rates are generally low on rangelands in comparison to croplands, increases in terrestrial carbon in rangelands resulting from management can account for significant carbon storage given the magnitude of this land resource. On two controlled sites, soil was sampled and analyzed to determine (1) the effect of grazing intensity and seasonality of grazing on native northern mixed-grass prairie, and (2) improvement practices on degraded northern mixed-grass prairie. The purpose of this task was to assess the carbon storage potential of rangelands and identify management practices that affect storage levels.

In 2003, researchers conducted field sampling to assess the effect of several drought years during the period of 1993 to 2002. Results suggested that drought can significantly impact rangeland SOC levels and, therefore, carbon storage. Resampling was conducted in 2006; results again suggested that climatic conditions may have overridden management effects on SOC due to the ecological lag of the severe drought of 2002. Analysis of grazing practices during this research effort suggested that there are beneficial effects of light grazing compared to heavy grazing and non-grazing with respect to increased SOC and nitrogen contents. In general, carbon storage in rangelands also increases with increased precipitation, although researchers identified threshold levels of precipitation where storage begins to decrease. They identified several practices that have been shown to impact carbon storage rates on rangelands. Other factors that will impact future storage potential include changes in production and quality of herbage; changes in the global environment, such as rising temperatures, changing precipitation, and rising CO₂ concentrations; and extreme climatic conditions, such as heat waves and droughts.

Lessons Learned

Rangelands cover about half of the world’s terrestrial area (47%). Due to the vast area, rangelands may play an important role in soil carbon storage. Although soil carbon storage rates are generally low on rangelands in comparison to croplands, increases in terrestrial carbon in rangelands resulting from management can account for significant carbon storage given the magnitude of this land resource. Analysis of grazing practices during this study suggested that there are beneficial effects of light grazing compared to heavy grazing and non-grazing with respect to increased soil organic carbon and nitrogen contents. In general, carbon storage in rangelands also increases with increased precipitation, although researchers identified threshold levels of precipitation where storage begins to decrease.

Links to EDX

Rangeland Sequestration Potential Assessment
Rangelands occupy approximately half of the world’s land area and store greater than 10% of the terrestrial biomass carbon and up to 30% of the global soil organic carbon (SOC). Although soil carbon storage rates are generally low on rangelands in comparison to croplands, increases in terrestrial carbon in rangelands resulting from management can account for significant carbon storage given the magnitude of this land resource. Despite the significance rangelands can play in carbon storage, our understanding remains limited. Researchers conducted a literature review to identify sustainably management practices that conserve existing rangeland carbon pools, as well as increase or restore carbon storage potentials for this type of ecosystem. The research team also reviewed the impact of grazing management on rangeland carbon dynamics, which are not well understood due to heterogeneity in grassland types. The literature review on the impact of grazing showed a wide variation of results, ranging from positive to negative to no response. On further review, the intensity of grazing appears to be a major factor in controlling rangeland SOC dynamics. In 2003, researchers conducted field sampling to assess the effect of several drought years during the period 1993 to 2002. Results suggested that drought can significantly impact rangeland SOC levels and, therefore, carbon storage. Resampling was conducted in 2006; results again suggested that climatic conditions may have overridden management effects on SOC due to the ecological lag of the severe drought of 2002. Analysis of grazing practices during this research effort suggested that there are beneficial effects of light grazing compared to heavy grazing and non-grazing with respect to increased SOC and nitrogen contents. In general, carbon storage in rangelands also increases with increased precipitation, although researchers identified threshold levels of precipitation where storage begins to decrease.

Sites

• Powder River Basin (Geological)
• Madison Formation
• Wallula Basalt Pilot
• Cropland (Terrestrial)
• Forestry (Terrestrial)
• Rangeland (Terrestrial)