Ingrid C. Burke

Bio: Ingrid C. Burke is an academic researcher from Yale University. The author has contributed to research in topics: Steppe & Soil organic matter. The author has an hindex of 64, co-authored 152 publications receiving 14472 citations. Previous affiliations of Ingrid C. Burke include University of Wyoming & Colorado State University.

Global-Scale Similarities in Nitrogen Release Patterns During Long-Term Decomposition

Abstract: Litter decomposition provides the primary source of mineral nitrogen (N) for biological activity in most terrestrial ecosystems. A 10-year decomposition experiment in 21 sites from seven biomes found that net N release from leaf litter is dominantly driven by the initial tissue N concentration and mass remaining regardless of climate, edaphic conditions, or biota. Arid grasslands exposed to high ultraviolet radiation were an exception, where net N release was insensitive to initial N. Roots released N linearly with decomposition and exhibited little net N immobilization. We suggest that fundamental constraints on decomposer physiologies lead to predictable global-scale patterns in net N release during decomposition.

The Importance of Land-Use Legacies to Ecology and Conservation

Abstract: Recognition of the importance of land-use history and its legacies in most ecological systems has been a major factor driving the recent focus on human activity as a legitimate and essential subject of environmental science. Ecologists, conservationists, and natural resource policymakers now recognize that the legacies of land-use activities continue to influence ecosystem structure and function for decades or centuries—or even longer—after those activities have ceased. Consequently, recognition of these historical legacies adds explanatory power to our understanding of modern conditions at scales from organisms to the globe and reduces missteps in anticipating or managing for future conditions. As a result, environmental history emerges as an integral part of ecological science and conservation planning. By considering diverse ecological phenomena, ranging from biodiversity and biogeochemical cycles to ecosystem resilience to anthropogenic stress, and by examining terrestrial and aquatic ecosyst...

Texture, climate, and cultivation effects on soil organic matter content in U.S. grassland soils

Abstract: Soil organic C content, a major source of system stability in agroecosystems, is controlled by many factors that have complex interactions. The purpose of this study was to evaluate the major controls over soil organic carbon content, and to predict regional patterns of carbon in range and cultivated soils. We obtained pedon and climate data for 500 rangeland and 300 cultivated soils in the U.S. Central Plains Grasslands, and statistically analyzed relationships between C and soil texture and climate. Regression models of the regional soils database indicated that organic C increased with precipitation and clay content, and decreased with temperature. Analysis of cultivated and rangeland soils indicated that C losses due to cultivation increased with precipitation, and that relative organic C losses are lowest in clay soils. Application of the regression models to a regional climate database showed potential soil organic matter losses to be highest in the northeastern section of the Central Plains Grasslands, decreasing generally from east to west. These statistical data analyses can be combined with more mechanistic models to evaluate controls of soil organic matter formation and turnover, and the implications for regional management. S ORGANIC MATTER is a major component of biogeochemical cycles of the major nutrient elements, and the quantity and quality of soil organic matter both reflect and control primary productivity. The amount of soil organic matter represents the balance of primary productivity and decomposition and as such is a sensitive and integrated measure of change in ecosystem function. Understanding the processes that control soil organic matter dynamics and their I.C. Burke, CM. Yonker, W.J. Parton, C.V. Cole and D.S. Schimel, Natural Resource Ecology Lab., Colorado State Univ., Fort Collins, CO 80523; and K. Flach, Agronomy Dep., Colorado State Univ., Fort Collins, CO 80523. Received 20 June 1988. 'Corresponding author. Published in Soil Sci. Soc. Am. J. 53:800-805 (1989). response to management is essential for informed use of agricultural land. Jenny (1980) describes four sets of state factors responsible for the formation of soil organic matter, and illustrates the influence of parent material, time, climate, and biota as individual controls over soil properties. Controls over soil organic matter properties may have complex interactions; separate analysis of such controls may limit useful predictions. Parton et al. (1988) illustrate the use of a mechanistic model in evaluating simultaneously changing controls. Although such models can be highly successful, field data are necessary to validate predictions across complex gradients. It is widely recognized that cultivation of grassland soils leads to depletion of soil organic matter (Alway, 1909; Russel, 1929; Hide and Metzger, 1939; Haas et al., 1957; and many others). Soil organic C losses of as much as 50% have been documented in the U.S. Central Plains Grasslands (Haas et al., 1957), with losses strongly dependent on management regime and regional location. The extent of soil organic matter depletion has been shown to depend upon the same variables as those controlling soil organic matter formation: climate (Haas et al., 1957; Honeycutt, 1986; Cole et al., 1989), soil texture (Tiessen et al., 1982; Schimel et al., 1985a), landscape position (Schimel et al., 1985a,b; Honeycutt, 1986; Yonker et al., 1988), and management regime (Janzen, 1987; Cole et al., 1988). An integrated assessment of soil organic matter losses across the U.S. Central Grasslands requires analysis of soils with varying temperature, precipitation, and soil physical properties. The objectives of this paper were threefold: (i) to establish quantitative relationships between native soil organic matter levels in the Central Plains Grasslands and key driving variables: precipitation, temperature, and soil texture; (ii) to develop predictions of cultivation induced soil organic carbon loss as a function BURKE ET AL.: TEXTURE, CLIMATE, AND CULTIVATION EFFECTS ON U.S. GRASSLAND SOILS 801 of climate and soil texture; and (iii) to use these predictions to map potential soil organic C depletion.

Anpp estimates from ndvi for the central grassland region of the united states

Abstract: Several studies have suggested the existence of a positive relationship be- tween the Normalized Difference Vegetation Index (NDVI) derived from AVHRR/NOAA satellite data and either biomass or annual aboveground net primary production (ANPP) for different geographic areas and ecosystems. We calibrated a 4-yr average of the ingegral of the NDVI (NDVI-J) using spatially aggregated values of ANPP. We also provided an estimate of the energy conversion efficiency coefficient (?) of Monteith's equation. This is the first attempt to calibrate a standard NDVI product for temperate perennial grasslands. We found a positive and statistically significant relationship between NDVI-I and ANPP for grassland areas with mean annual precipitation between 280 and 1150 mm, and mean annual temperature between 40 and 20'C. Depending on the method used to estimate the fraction of photosynthetic active radiation, the energy conversion officency coefficient was constant (0.24 g C/MJ), or varied across the precipitation gradient, from 0.10 g C/MJ for the least productive to 0.20 g C/MJ for the most productive sites.

Simple three‐pool model accurately describes patterns of long‐term litter decomposition in diverse climates

Abstract: As atmospheric CO 2 increases, ecosystem carbon sequestration will largely depend on how global changes in climate will alter the balance between net primary production and decomposition The response of primary production to climatic change has been examined using well-validated mechanistic models, but the same is not true for decomposition, a primary source of atmospheric CO 2 We used the Long-term Intersite Decomposition Experiment Team (LIDET) dataset and model-selection techniques to choose and parameterize a model that describes global patterns of litter decomposition Mass loss was best represented by a three-pool negative exponential model, with a rapidly decomposing labile pool, an intermediate pool representing cellulose, and a recalcitrant pool The initial litter lignin/nitrogen ratio defined the size of labile and intermediate pools Lignin content determined the size of the recalcitrant pool The decomposition rate of all pools was modified by climate, but the intermediate pool's decomposition rate was also controlled by relative amounts of litter cellulose and lignin (indicative of lignin-encrusted cellulose) The effect of climate on decomposition was best represented by a composite variable that multiplied a water-stress function by the Lloyd and Taylor variable Q 10 temperature function Although our model explained nearly 70% of the variation in LIDET data, we observed systematic deviations from model predictions Below- and aboveground material decomposed at notably different rates, depending on the decomposition stage Decomposition in certain ecosystem-specific environmental conditions was not well represented by our model; this included roots in very wet and cold soils, and aboveground litter in N-rich and arid sites Despite these limitations, our model may still be extremely useful for global modeling efforts, because it accurately (R 2 = 06804) described general patterns of long-term global decomposition for a wide array of litter types, using relatively minimal climatic and litter quality data

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The vertical distribution of soil organic carbon and its relation to climate and vegetation

Abstract: As the largest pool of terrestrial organic carbon, soils interact strongly with atmospheric composition, climate, and land cover change. Our capacity to predict and ameliorate the consequences of global change depends in part on a better understanding of the distributions and controls of soil organic carbon (SOC) and how vegetation change may affect SOC distributions with depth. The goals of this paper are (1) to examine the association of SOC content with climate and soil texture at different soil depths; (2) to test the hypothesis that vegetation type, through patterns of allocation, is a dominant control on the vertical distribution of SOC; and (3) to estimate global SOC storage to 3 m, including an analysis of the potential effects of vegetation change on soil carbon storage. We based our analysis on .2700 soil profiles in three global databases supplemented with data for climate, vegetation, and land use. The analysis focused on mineral soil layers. Plant functional types significantly affected the vertical distribution of SOC. The per- centage of SOC in the top 20 cm (relative to the first meter) averaged 33%, 42%, and 50% for shrublands, grasslands, and forests, respectively. In shrublands, the amount of SOC in the second and third meters was 77% of that in the first meter; in forests and grasslands, the totals were 56% and 43%, respectively. Globally, the relative distribution of SOC with depth had a slightly stronger association with vegetation than with climate, but the opposite was true for the absolute amount of SOC. Total SOC content increased with precipitation and clay content and decreased with temperature. The importance of these controls switched with depth, climate dominating in shallow layers and clay content dominating in deeper layers, possibly due to increasing percentages of slowly cycling SOC fractions at depth. To control for the effects of climate on vegetation, we grouped soils within climatic ranges and compared distributions for vegetation types within each range. The percentage of SOC in the top 20 cm relative to the first meter varied from 29% in cold arid shrublands to 57% in cold humid forests and, for a given climate, was always deepest in shrublands, inter- mediate in grasslands, and shallowest in forests ( P , 0.05 in all cases). The effect of vegetation type was more important than the direct effect of precipitation in this analysis. These data suggest that shoot/root allocations combined with vertical root distributions, affect the distribution of SOC with depth. Global SOC storage in the to p3mo fsoil was 2344 Pg C, or 56% more than the 1502 Pg estimated for the first meter (which is similar to the total SOC estimates of 1500-1600 Pg made by other researchers). Global totals for the second and third meters were 491 and 351 Pg C, and the biomes with the most SOC at 1-3 m depth were tropical evergreen forests (158 Pg C) and tropical grasslands/savannas (146 Pg C). Our work suggests that plant functional types, through differences in allocation, help to control SOC distributions with depth in the soil. Our analysis also highlights the potential importance of vegetation change and SOC pools for carbon sequestration strategies.

Humans integrate visual and haptic information in a statistically optimal fashion.

Abstract: When a person looks at an object while exploring it with their hand, vision and touch both provide information for estimating the properties of the object. Vision frequently dominates the integrated visual-haptic percept, for example when judging size, shape or position, but in some circumstances the percept is clearly affected by haptics. Here we propose that a general principle, which minimizes variance in the final estimate, determines the degree to which vision or haptics dominates. This principle is realized by using maximum-likelihood estimation to combine the inputs. To investigate cue combination quantitatively, we first measured the variances associated with visual and haptic estimation of height. We then used these measurements to construct a maximum-likelihood integrator. This model behaved very similarly to humans in a visual-haptic task. Thus, the nervous system seems to combine visual and haptic information in a fashion that is similar to a maximum-likelihood integrator. Visual dominance occurs when the variance associated with visual estimation is lower than that associated with haptic estimation.

Land Clearing and the Biofuel Carbon Debt

Abstract: Increasing energy use, climate change, and carbon dioxide (CO2) emissions from fossil fuels make switching to lowcarbon fuels a high priority. Biofuels are a potential lowcarbon energy source, but whether biofuels offer carbon savings depends on how they are produced. Converting rainforests, peatlands, savannas, or grasslands to produce food-based biofuels in Brazil, Southeast Asia, and the United States creates a ‘biofuel carbon debt’ by releasing 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions these biofuels provide by displacing fossil fuels. In contrast, biofuels made from waste biomass or from biomass grown on abandoned agricultural lands planted with perennials incur little or no carbon debt and offer immediate and sustained GHG advantages. Demand for alternatives to petroleum is increasing the production of biofuels from food crops such as corn, sugarcane, soybeans and palms. As a result, land in