USGS - science for a changing world

Permafrost

Permafrost (defined as ground which has remained frozen for two or more years) is found at high latitudes, including portions of the boreal forest. Permafrost soils store a great deal of carbon, keeping this carbon out of the atmosphere. However, this permafrost is rapidly thawing. As permafrost thaws, the water stored within permafrost can pond, and form bogs or lakes, or it can drain, drying out the soils. The fate of the carbon stored within the permafrost differs depending on which of these scenarios occurs and the composition of the microbial community inhabiting permafrost soils. Will this carbon continue to be stored (or sequestered) or will much of this carbon be lost to the atmosphere as carbon dioxide (CO2) and methane (CH4)? The goal of two of our research projects, The Fate of Carbon in Soil Systems and ECOSCAPE, is to determine what data are needed to predict these outcomes and to model the patterns of future carbon storage and release across these northern landscapes.

Fire

Wildfires are a natural disturbance of boreal (a.k.a. northern) forests. However, it appears that regional warming is increasing both the area burned and severity of this burning. Studying the amount carbon lost to an ecosystem due to fire, the implications of this loss to areas underlain by permafrost (or frozen soil), and how these ecosystems recover allows us to understand how changes in boreal fire regime will impact the global climate. For this reason, one of our USGS projects, Fate of Carbon in Soil Systems, has been investigating the role of fire in boreal forests for over a decade.

Soil Microbiology

Over the past several hundred years, human activity has greatly accelerated the rate of environmental change. Climate change, elevated atmospheric CO2, wildfire, hydrologic change, and the loss of the Earth’s flora and fauna all dramatically affect ecosystem processes. All the while, we are continuing to demand more from our soil resources for ecosystem productivity and services. Although many environmental impacts are dramatic and clear, what is less visible is their effect on microbial communities that drive critical biogeochemical processes. There exists a vast diversity of microorganisms in soil, and we do not yet understand what structures microbial communities nor do we understand how changes in their composition and diversity might alter the manner in which terrestrial ecosystems function. Our research focuses on filling this fundamental gap.

Soil Development

Pedogenesis is the process through which the chemical and physical properties of soils develop over time. Long-term storage and stabilization of organic matter, and thus carbon, in soils is closely tied to the soil properties such as differences in soil mineralogy, hydrology, and/or biologic communities. In order to better understand what soils are most susceptible to climate and land use change as well as which soils may have the greatest potential for future carbon storage, we quantify soil development and to link it to biogeochemical cycling. The classic view of soil development, put forth by Hans Jenny and others, characterizes soil development as a function of six factors: climate, organisms (biology), relief (elevation and slope of the land surface), parent material, time, and humans. The influences of these different factors on soil characteristics are evaluated by comparing soils spanning natural gradients. Our work takes advantage of natural gradients of time, known as landform chronosequences, to examine how soil development controls carbon cycling. In addition, we compare soils from many different chronosequences to examine the interaction of time with other soil forming factors.

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