The long-term goal of this project is to develop an integrated, systems-based understanding of soil-water-plant-animal relationships influencing carbon sequestration and GHG emissions in rangeland and pasture ecosystems.
In this project, we evaluate the multiple ecological processes and land management decisions influencing carbon, water, and energy cycling in rangelands and grazing pastures. We aim to better understand the role of cattle grazing as a catalyzer and an integral part of the ecosystem. Our work is being conducted in many landscapes, ranging from sagebrush steppe to juniper woodlands to meadows and cultivated pastures. We are assessing multiple hydrology and ecology variables, including above- and below-ground carbon pools and GHG emissions.
Well-managed rangeland and pasture ecosystems can contribute to increased carbon sequestration and mitigation of GHG emissions through increased soil water infiltration, fine-fuel reduction, and improved soil, water, and vegetation conditions overall. Information generated from this study can be used to establish baseline conditions for carbon sequestration, improve land management practices to increase carbon capture and storage, and inform policy regarding the subject.
Rangelands cover over half of the Earth's land surface and store 10 to 30 percent of total soil organic carbon (SOC). In rangelands, SOC may represent as much as 95 percent of the total terrestrial carbon pool, with the remainder of terrestrial carbon stored as plant biomass. Sound land management practices that maintain or enhance the resilience of rangeland ecosystems can prevent soil organic carbon and biomass carbon losses by decreasing the potential for encroachment of invasive vegetation species and catastrophic wildfire events.
Ongoing study results show mean soil C content ranges from 0.5% to 1.6% in sagebrush steppe. In sagebrush landscape areas where perennial grasses have been established, the mean C content is 3.9%.
Juniper study
Thirteen years after juniper removal, the increased presence of deep-rooted perennial grasses and more shrubs in the treated watershed was also reflected in higher root carbon content.
There is greater root and soil carbon content (Ton/C/ha) in areas where juniper has been removed than in untreated areas.
Besides multiple other ecological benefits (e.g., greater herbaceous yield and cover, increased streamflow, and springflow), the increased below-ground C content in the treated WS helped offset the C losses from juniper tree removal.
This study will be replicated in 2024 to evaluate above- and below-ground carbon pools nearly 20 years after treatment.
Publications
Ecosystem carbon in relation to woody plant encroachment and control: juniper systems in Oregon, USA
Irrigated and non-irrigated pastures
Ongoing study results show mean soil C content ranging from 2% to 5% in irrigated and non-irrigated pastures in eastern and western Oregon.
