@conference {50796,
	title = {Simulation modelling of soil inorganic carbon in arid environments},
	booktitle = {88th Annual Meeting, Ecological Society of America},
	year = {2003},
	month = {August 3-8, 2003},
	pages = {238},
	address = {Savannah, GA},
	abstract = {Pedogenic carbonate, or soil inorganic carbon, is an important constituent of subhumid-to-arid soils throughout the world.  Although terrestrial carbon cycling science has placed more emphasis on organic carbon, arid and semiarid soils store approximately ten times more inorganic carbon than organic.  It has been estimated that more than 8 x 1014 kg of C are sequestered globally in calcic and petrocalcic horizons of Aridisols and Mollisols.  Our goal was to examine and test hypotheses regarding the relationship of calcium carbonate (CaCO3) in arid lands to atmospheric CO2 sequestration.  The magnitude of soil inorganic carbon flux with the atmosphere is difficult to estimate at local, regional or global scales.  We developed a conceptual model and an associated process-based model to simulate the rate of formation and vertical distribution of CaCO3 in soil horizons in the arid southwestern U.S.  The model depicts short term processes of CaCO3 precipitation and dissolution that occur in periods of days to centuries to millennia.  We use the model to illustrate the environmental and biotic conditions that control the CaCO3 source-to-sink relation.  Initial findings show that pedogenic carbonate can serve not only as a sink, but also as a source for CO2.  Our simulation modelling framework helps illustrate the historic and future conditions under which soil carbonates alternate between storing and releasing CO2 to the atmosphere.},
	author = {K. A. Mitchell and Curtis H. Monger and Jeffrey E. Herrick and Debra C. Peters}
}
@conference {50909,
	title = {Comparing and contrasting scaling approaches across ecological disciplines: case studies of vegetation, biogeochemical and animal dynamics},
	booktitle = {17th Annual Symposium, US-International Association for Landscape Ecology},
	year = {2002},
	month = {April 23-26, 200},
	pages = {88-89},
	abstract = {Numerous approaches have been taken to evaluate spatial scaling relationships in ecology.  These approaches can be generalized into three categories: those that are nonspatial, those that are spatially explicit but not spatially interactive, and those that are both spatially explicit and spatially interactive.  While it is relatively easy to categorize a given study within these three approaches, a more general perspective comparing and contrasting how these approaches are used within different ecological disciplines is largely lacking.  Here we compare and contrast case studies related to vegetation, biogeochemical and animal dynamics, discuss the implications of selecting a given approach, and note insights that can be obtained from a cross-disciplinary perspective.  Understanding the similarities and differences among scaling approaches is particularly important in cases where processes from different disciplines need to be coupled to one another.  An example of such couplings and their associated scale dependencies are highlighted by a case study in which drought produces vegetation mortality (vegetation dynamics) which was initially and subsequently exacerbated by grazing (animal dynamics) and has triggered large increases in runoff, erosion, and losses of carbon and nutrients (biogeochemistry).  Our overview provides ideas for comparing scaling approaches while being cognizant of implicit assumptions and offers broader insights into scaling relationships across disciplines in ecology.},
	author = {K. A. Mitchell and David D. Breshears and C.D. Allen and Brandon T Bestelmeyer and Gross, J.E.}
}
@conference {50910,
	title = {Long-term changes in carbon pools accompanying shrub invasion of a desert grassland: the Jornada Experimental Range, 1850-today},
	booktitle = {87th Annual Meeting, Ecological Society of America},
	year = {2002},
	month = {August 4-9, 2002},
	pages = {215},
	address = {Tucson, AZ},
	abstract = {Coincident with a worldwide increase in the abundance of woody plants within former grasslands, desert grasslands throughout the southwestern U.S. have experienced a substantial increase in the abundance of shrubs during the last century.  The displacement of grasslands with grass-shrublands has had important implications for ecosystem carbon cycling and rates of carbon sequestration.  Building on a history of biogeochemistry research conducted at the Jornada Experimental Range in southern New Mexico, we measured and modelled aboveground and belowground carbon storage in black grama grasslands (Bouteloua eriopoda) and mesquite (Prosopis glandulosa) and creosotebush (Larrea tridentata) shrublands across the Jornada basin.  We combined the simulation modeling predictions of the CENTURY model with data from recovered historical vegetation maps of 1858, 1915, 1928 and modern vegetation maps.  Our results support the hypothesis that shrub encroachment into grasslands increases storage of belowground carbon.  Landscape-level mapped estimates of carbon pools indicate that the desert grassland ecosystem of the Jornada basin may have served as a carbon sink during the last century.},
	author = {K. A. Mitchell and Debra C. Peters and Curtis H. Monger and Jeffrey E. Herrick}
}
@conference {50911,
	title = {Quantifying changes in carbon pools accompanying shrub invasion of a desert grassland},
	booktitle = {17th Annual Symposium, International Association for Landscape Ecology},
	year = {2002},
	month = {April 23, 2002},
	pages = {110},
	address = {Lincoln, NE},
	abstract = {Coincident with a worldwide increase in the abundance of woody plants within former grasslands, desert grasslands through the southwestern U.S. have experienced a substantial increase in the abundance of shrubs during the last century.  These changes in grassland structure have had important implications for ecosystem carbon cycling and rates of carbon sequestration.  Building on a history of biogeochemistry research conducted at the Jornada Experimental Range in southern New Mexico, we measured and modeled above and below-ground carbon storage in black grama grasslands (Bouteloua eriopoda) and mesquite (Prosopis glandulosa) and creosotebush (Larrea tridentata) shrublands across the Jornada basin.  Our research approach combined direct field measurement of carbon pools, extensive use of existing Jornada datasets and simulation modeling using the CENTURY model in an effort to scale field-based measurements to landscape-level estimates of carbon pools.  Our results refute the commonly held thesis that carbon storage shifts from below to aboveground with shrub invasion of grasslands, but overall net ecosystem carbon remains the same.  Landscape-level mapped estimates of carbon pools indicate that the desert grassland ecosystem of the Jornada basin may have served as a carbon sink during the last century.},
	author = {K. A. Mitchell and Debra C. Peters and Curtis H. Monger and Jeffrey E. Herrick}
}
