Determining Carbon Sequestration in Soil: Canopy and Intercanopy Zones of the Sagebrush Steppe at Reynolds Creek

Document Type

Student Presentation

Presentation Date

April 2016

Faculty Sponsor

Marie-Anne de Graaff


Terrestrial soils are important carbon (C) sinks for the biosphere. Arid and semi-arid ecosystems specifically cover more than 35% of the Earth’s land surface, and they contain 33% of above and below ground terrestrial C reserves. Thus, soil C dynamics in these ecosystems, and their processes impact atmospheric carbon dioxide (CO2) concentrations. As a result, it is important to understand soil C stability across the landscape of arid ecosystems. In this study, we aim to quantify soil organic C stability across a depth profile at an elevation gradient in a semi-arid ecosystem. Our experiment is conducted at Reynolds Creek Experimental Watershed, located in Southwestern Idaho. We collected soil samples (0-30 cm depth; 4.8 cm diameter corer) from four locations ranging in elevation from 1180m to 2111m, spanning a mean annual precipitation range of 240mm to 795mm, and a temperature gradient of 5 degrees Celsius. The main vegetation at each one of the locations is Artemisia tridentate subsp. Wyomingensis, Artemisia tridentate subsp. Wyomingensis, Artemisia arbuscular, and Artemisia tridentate subsp. Vaseyana, from lowest elevations to the highest. We collected soil samples from underneath the shrub canopy and from canopy interspaces of sagebrush plants at each location (n =5). These soil samples were split by four depth increments (0-5 cm, 5-10 cm, 10-20 cm, and 20-30 cm) and physically fractionated into coarse and fine particulate organic matter, silt and clay fractions using wet sieving and centrifugation. Soil C and N percentages in each fraction across all soil depth was quantified using a Flash EA analyzer. We will determine the stability of C using its relative proportion in each fraction, as C associated with mineral fractions (silt, clay) is more stable than C in particulate organic matter.

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