Papers by Karen Updegraff
Bulletin of the Ecological Society of America, 1995
Staff Paper Series Department of Forest Resources University of Minnesota, Mar 1, 2000
Environmental Modelling and Software
Green Trading Markets, 2005
Biogeochemistry, 1998
The ability to predict the effects of climate change on trace gas fluxes requires a knowledge of ... more The ability to predict the effects of climate change on trace gas fluxes requires a knowledge of microbial temperature responses. However, the response of a microbial community to temperature in a given substrate may be complicated by its thermal history. To examine the effect of sequentially changing temperature on methane and carbon dioxide production in different peat types, we incubated anaerobic peat samples from 3 types of northern peatlands, a bog, a sedge fen and a cedar swamp, in both rising and falling temperature regimes. Graphic and statistical comparisons of the different temperature regimes suggest hysteresis in microbial response to temperature, although the absolute rates at any given temperature often did not differ. Where regressions for temperature response (Arrhenius plots) were significant, they generally differed between temperature regimes. The greatest differences among treatments occurred during the first half of the 40-d incubation. Increases in carbon diox...
Soil Science Society of America Journal, 2001
thought of as the rate of replenishment or the buffer capacity of the dissolved inorganic nutrien... more thought of as the rate of replenishment or the buffer capacity of the dissolved inorganic nutrient pool. How-Despite the importance of nutrient availability in determining ecoever, measurement of nutrient supply rates is a difficult system structure and function, it is difficult to quantify in an absolute sense because of the complexity of nutrient cycles and methodological endeavor, as they are determined by the relative sizes limitations. Others have compared nutrient availability indices for of the labile, organic, and recalcitrant inorganic pools upland soils, but few comparative studies have been done in organic in the soil, and rates of transformation and transfer soils. Objectives of this study were, (i) to determine if N and P among the pools (Stevenson, 1986; Binkley and Hart, availability change in a predictable manner across an ombrotrophic-1989). Furthermore, the importance of particular pools minerotrophic gradient in 16 wetlands in northern Minnesota, and and transformations varies among nutrients. Environ-(ii) to compare various laboratory and field indices of soil nutrient mental controls over all of these factors must also be availability in a diverse group of organic soils. Ombrotrophic wetlands considered. Any particular method of determining nureceive only atmospheric inputs of ions, while minerotrophic wetlands trient availability only measures one to several of these also receive groundwater or overland water inputs. We compared pools and fluxes and the pools are often operationally the following nutrient availability indices: 2-and 59-wk laboratory mineralization potentials, labile P and N pools determined from a defined, so any measure of nutrient availability must be kinetic mineralization model, total and extractable soil N and P pools, considered an index (Binkley and Hart, 1989; Binkley plant N and P concentrations, and H-OH and HCO Ϫ 3 charged resins.
Renewable Agriculture and Food Systems, 2004
The conversion of cropland to the production of woody biomass, or short-rotation woody crops (SRW... more The conversion of cropland to the production of woody biomass, or short-rotation woody crops (SRWCs), has the potential to provide an economic alternative to Midwestern farmers, while simultaneously offering an environmental dividend in the form of reduced erosion and nutrient pollution of streams. However, notwithstanding a wealth of plot-scale and anecdotal data suggestive of these bene®ts, there are few watershed-scale integrated analyses on which to base regional policy decisions regarding incentives to convert ®elds to SRWCs. This study applied a ®eld-scale runoff, sediment and nutrient transport model (Agricultural Drainage and Pesticide Transport, ADAPT) to a simulation of 10, 20 and 30% cropland conversion to SRWCs, grown on a 5-year rotation, in a representative Minnesota River sub-watershed. While the generation of a highly precise simulation would require extensive calibration of the model, its application with parameters previously calibrated to neighboring, similar watersheds provided reasonably robust results that indicated real differences resulting from cropland conversion. At the highest conversion level, mean annual runoff was reduced by up to 9%, sediment loads by 28% and nitrogen (N) loads by 15%, although total phosphorus (P) loads increased by 2% relative to the no-SRWC scenario. However, the relative bene®ts of conversion at the ®eld level were contingent on soil type, drainage status and the alternative crop. These differences provide useful insights with respect to the targeting of possible conversion incentives.
Oikos, 2003
2003. Global warming and the export of dissolved organic carbon from boreal peatlands. -Oikos 100... more 2003. Global warming and the export of dissolved organic carbon from boreal peatlands. -Oikos 100: 380-386.
Mitigation and Adaptation Strategies for Global Change, 2005
Page 1. C-LOCK (PATENT PENDING): A SYSTEM FOR ESTIMATING AND CERTIFYING CARBON EMISSION REDUCTION... more Page 1. C-LOCK (PATENT PENDING): A SYSTEM FOR ESTIMATING AND CERTIFYING CARBON EMISSION REDUCTION CREDITS FOR THE SEQUESTRATION OF SOIL CARBON ON AGRICULTURAL LAND PATRICK ...
Fuel Processing Technology, 2005
ABSTRACT C-Lock (patent pending) is a system that has been designed to produce standardized carbo... more ABSTRACT C-Lock (patent pending) is a system that has been designed to produce standardized carbon emission reduction credits (CERCs) that minimize litigation risks to purchasers and maximize the potential value to agricultural producers. C-Lock provides a web-based user interface linking producer-supplied, verifiable, management data, a detailed regional-scale GIS, and a biogeochemical model (CENTURY). Output includes historical incremental carbon sequestration since 1990 and predictions of future sequestration, packaged to satisfy evolving regulatory standards. C-Lock incorporates a unique uncertainty analysis and a three-level verification system to produce certified CERCs for specific land parcels in a way that is reproducible, equitable, and regionally defensible.Using a South Dakota farm as an example, the authors show how, by avoiding reliance on field sampling, this system can minimize measurement and monitoring costs. It allows individual producers a high degree of control over contract design and marketing, thereby reducing transaction costs. The transparent, standardized, and auditable procedure produces CERCs of maximum value to those seeking emission offsets.
Environmental Modelling & Software, 2010
Ecology, 1998
We examined rates of C, N, and P mineralization in soils from 16 northern Minnesota wetlands that... more We examined rates of C, N, and P mineralization in soils from 16 northern Minnesota wetlands that occur across an ombrotrophic-minerotrophic gradient. Soils were incubated at 30ЊC under aerobic and anaerobic conditions for 59 wk, and the results were fit with a two-pool kinetic model. Additionally, 39 different soil quality variables were used in a principal components analysis (PCA) to predict mineralization rates.
Ecology, 2008
Peatlands comprise a globally important carbon pool whose input-output budgets may be significant... more Peatlands comprise a globally important carbon pool whose input-output budgets may be significantly altered by climate change. To experimentally determine the sensitivity of the carbon stored in peatlands to climate change, we constructed a mesocosm facility with 54 peat monoliths from a bog and fen in northern Minnesota, USA. These mesocosms were subjected to nine combinations of heat and water-table levels over eight years. Bog mesocosms initially accumulated soil carbon, with greater gains in wetter mesocosms, but after three years no further water-table effects occurred. In contrast, fen mesocosms lost or had no change in soil carbon, with the greatest losses in drier and warmer mesocosms. Changes in soil-carbon storage resulted in concomitant changes in water-table depth, so that water-table depths were similar to those in the natural source sites by the end of the experiment regardless of the initial treatment. These results were primarily due to watertable effects on Sphagnum moss production in the bog mesocosms and to a more complicated suite of warming and water-table effects on production and decomposition in the fen mesocosms. We show that different kinds of peatlands will rapidly gain or lose carbon following hydrological disturbance until they return to their characteristic (''equilibrium'') water-table levels. Our results illustrate the potential for a rapid homeostatic response of these ecosystems to future climate change at small spatial scales. Climate change will likely also interact with other carbon cycle-hydrological feedbacks at the scale of the entire peatland over longer time frames and larger spatial scales.
Ecological Applications, 2001
Ecological Applications, 1995
Ecological Applications, 1999
Large-scale changes in climate may have many unexpected effects on ecosystems, given the importan... more Large-scale changes in climate may have many unexpected effects on ecosystems, given the importance of climate as a control over almost all ecosystem attributes and their many internal feedbacks. In particular, the interactions among energy flux, plant dynamics, and soil carbon and nutrient cycling are poorly known. In this study, we examined biotic controls over soil temperature and evapotranspiration (ET) in a climate change experiment in two peatlands, a bog and a fen. Bogs are isolated from groundwater inputs (i.e., ombrogenous) and are acidic, whereas fens receive groundwater inputs (i.e., minerogenous) and are more alkaline. They also have many associated differences in soil chemistry, nutrient availability, and plant communities.
Canadian Journal of Forest Research, 1990
The nitrogen (N) dynamics within short-rotation intensive-culture forest plantations are poorly u... more The nitrogen (N) dynamics within short-rotation intensive-culture forest plantations are poorly understood. We developed a N budget for a 3-year-old hybrid poplar plantation under short-rotation intensive-culture management in northwestern Minnesota. Measured pools ...
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Papers by Karen Updegraff