Get reliable rangeland science

In order to offset CO2 increases in the atmosphere, research aimed at determining the potential to enhance carbon storage in terrestrial ecosystems has become imperative.  In addition to occupying a large area of the earth's surface (~40%), grasslands store much of their carbon as soil organic matter below-ground, where it remains relatively protected from above-ground disturbances.  The stability of soil carbon, however, also varies with organic matter size fractions, and differences in this stability may help explain how grasslands may be managed to optimize carbon storage in the long-term.  The purpose of this study was to quantify the size fractions of organic matter in northern temperate grassland soils.  To do this, we evaluated carbon levels in small (<53 mm), medium (53 – 230 mm), and coarse (> 230 mm) fractions of soils associated with grasslands exposed and protected from livestock grazing, and further stratified to represent a large gradient in agro-climatic conditions (~300-500 mm of annual precipitation) across Alberta, Canada.  Soil carbon was assessed from 10 bulked sub-sampled cores extracted to 30 cm depth both inside and outside a network of long-term cattle exclosures managed by Alberta Environment and Sustainable Resource Development.  Results of this study will have implications for characterizing carbon stores in these ecosystems, as well as understanding how differences in growing conditions and grazing history may alter carbon stability, and ultimately influence the role of these grasslands in serving as important carbon sinks.