Physical Sciences and Mathematics Commons^™

Geographic Variation, Null Hypotheses, And Subspecies Limits In The California Gnatcatcher: A Response To Mccormack And Maley, Robert M. Zink, Jeffrey G. Groth, Hernan Vázquez-Miranda

Papers in Natural Resources

We interpreted the results of nuclear DNA sequencing to be inconsistent with the recognition of California Gnatcatcher (Polioptila californica) subspecies. McCormack and Maley (2015) suggested that our data did support 2 taxa, one of which was P. c. californica, listed as Threatened under the Endangered Species Act (ESA). We summarize here how 2 sets of researchers with access to the same data reached different conclusions by including different analyses. We included the southern subspecies’ boundary from the taxonomy of Atwood (1991), the taxonomic basis for the ESA listing, which resulted in an Analysis of Molecular Variance that …

Fluctuating Fire Regimes And Their Historical Effects On Genetic Variation In An Endangered Shrubland Specialist, Hernan Vázquez-Miranda, Kelly R. Barr, C. Craig Farquhar, Robert M. Zink

Papers in Natural Resources

The Pleistocene was characterized by worldwide shifts in community compositions. Some of these shifts were a result of changes in fire regimes, which influenced the distribution of species belonging to fire-dependent communities. We studied an endangered juniper–oak shrubland specialist, the black-capped vireo (Vireo atricapilla). This species was locally extirpated in parts of Texas and Oklahoma by the end of the 1980s as a result of habitat change and loss, predation, brood parasitism, and anthropogenic fire suppression. We sequenced multiple nuclear loci and used coalescence methods to obtain a deeper understanding of historical population trends than that typically available …

Modeling Gross Primary Production Of Maize And Soybean Croplands Using Light Quality, Temperature, Water Stress, And Phenology, Anthony L. Nguy-Robertson, Andrew E. Suyker, Xiangming Xiao

Papers in Natural Resources

Vegetation productivity metrics, such as gross primary production (GPP) may be determined from the efficiency with which light is converted into photosynthates, or light use efficiency (ϵ). Therefore, accurate measurements and modeling of ϵ is important for estimating GPP in each ecosystem. Previous studies have quantified the impacts of biophysical parameters on light use efficiency based GPP models. Here we enhance previous models utilizing four scalars for light quality (i.e., cloudiness), temperature, water stress, and phenology for data collected from both maize and soybean crops at three Nebraska AmeriFlux sites between 2001 and 2012 (maize: 26 field-years; soybean: …

Parent-Offspring Resemblance In Colony-Specific Adult Survival Of Cliff Swallows, Charles R. Brown, Erin A. Roche, Mary Bomberger Brown

Papers in Natural Resources

Survival is a key component of fitness. Species that occupy discrete breeding colonies with different characteristics are often exposed to varying costs and benefits associated with group size or environmental conditions, and survival is an integrative net measure of these effects. We investigated the extent to which survival probability of adult (≥ 1-year old) cliff swallows (Petrochelidon pyrrhonota) occupying different colonies resembled that of their parental cohort and thus whether the natal colony had long-term effects on individuals. Individuals were cross-fostered between colonies soon after hatching and their presence as breeders monitored at colonies in the western Nebraska …

Variation In Avian Vocalizations During The Non-Breeding Season In Response To Traffic Noise, Amy I. Oden, Mary Bomberger Brown, Mark E. Burbach, James R. Brandle, John E. Quinn

Papers in Natural Resources

Low-frequency traffic noise that leads to acoustic masking of vocalizations may cause birds to alter the frequencies or other components of their vocalizations in order to be heard by conspecifics and others. Altering parts of a vocalization may result in poorer vocal performance or the message contained in the vocalization being received incorrectly. During the winters of 2011–2012 and 2012–2013, we recorded and measured the “chick-a-dee” call of Black-capped Chickadees (Poecile atricapillus) and the “po-ta-to-chip” call of American Goldfinches (Spinus tristis) to determine whether components of the calls produced in areas of high traffic noise and …

Uncertainty In Simulating Gross Primary Production Of Cropland Ecosystem From Satellite-Based Models, Wenping Yuan, Wenwen Cai, Anthony L. Nguy-Robertson, Huajun Fang, Andrew E. Suyker, Yang Chen, Wenjie Dong, Shuguang Liu, Haicheng Zhang

Papers in Natural Resources

Accurate estimates of gross primary production (GPP) for croplands are needed to assess carbon cycle and crop yield. Satellite-based models have been developed to monitor spatial and temporal GPP patterns. However, there are still large uncertainties in estimating cropland GPP. This study compares three light use efficiency (LUE) models (MODIS-GPP, EC-LUE, and VPM) with eddy-covariance measurements at three adjacent AmeriFlux crop sites located near Mead, Nebraska, USA. These sites have different croprotation systems (continuous maize vs. maize and soybean rotated annually) and water management practices (irrigation vs. rainfed). The results reveal several major uncertainties in estimating GPP which need to …

Development Modeling Of Lucilia Sericata (Diptera: Calliphoridae), Amanda Roe, Leon G. Higley

Papers in Natural Resources

The relationship between insect development and temperature has been well established and has a wide range of uses, including the use of blow flies for postmortem (PMI) interval estimations in death investigations. To use insects in estimating PMI, we must be able to determine the insect age at the time of discovery and backtrack to time of oviposition. Unfortunately, existing development models of forensically important insects are only linear approximations and do not take into account the curvilinear properties experienced at extreme temperatures. A series of experiments were conducted with Lucilia sericata, a forensically important blow fly species, that met …

Joint Control Of Terrestrial Gross Primary Productivity By Plant Phenology And Physiology, Jianyang Xia, Shuli Niu, Philippe Ciais, Ivan A. Janssens, Jiquan Chen, Christof Ammann, Altaf Arain, Peter D. Blanken, Alessandro Cescatti, Damien Bonal, Nina Buchmann, Peter S. Curtis, Shiping Chen, Jinwei Dong, Lawrence B. Flanagan, Christian Frankenberg, Teodoro Georgiadis, Christopher M. Gough, Dafeng Hui, Gerard Kiely, Jianwei Li, Magnus Lund, Vincenzo Magliulo, Barbara Marcolla, Lutz Merbold, Leonardo Montagnani, Eddy J. Moors, Jorgen E. Olesen, Shilong Piao, Antonio Raschi, Oliver Roupsard, Andrew E. Suyker, Marek Urbaniak, Francesco P. Vaccari, Andrej Varlagin, Timo Vesala, Matthew Wilkinson, Ensheng Weng, Georg Wohlfahrt, Liming Yan, Yiqi Luo

Papers in Natural Resources

Terrestrial gross primary productivity (GPP) varies greatly over time and space. A better understanding of this variability is necessary for more accurate predictions of the future climate–carbon cycle feedback. Recent studies have suggested that variability in GPP is driven by a broad range of biotic and abiotic factors operating mainly through changes in vegetation phenology and physiological processes. However, it is still unclear how plant phenology and physiology can be integrated to explain the spatiotemporal variability of terrestrial GPP. Based on analyses of eddy–covariance and satellite-derived data, we decomposed annual terrestrial GPP into the length of the CO2 uptake period …

Productivity, Absorbed Photosynthetically Active Radiation, And Light Use Efficiency In Crops: Implications For Remote Sensing Of Crop Primary Production, Anatoly A. Gitelson, Yi Peng, Timothy J. Arkebauer, Andrew E. Suyker

Papers in Natural Resources

Vegetation productivity metrics such as gross primary production (GPP) at the canopy scale are greatly affected by the efficiency of using absorbed radiation for photosynthesis, or light use efficiency (LUE). Thus, close investigation of the relationships between canopy GPP and photosynthetically active radiation absorbed by vegetation is the basis for quantification of LUE. We used multiyear observations over irrigated and rainfed contrasting C3 (soybean) and C4 (maize) crops having different physiology, leaf structure, and canopy architecture to establish the relationships between canopy GPP and radiation absorbed by vegetation and quantify LUE. Although multiple LUE definitions are reported in the literature, …

How Climate Change Has Affected The Spatio-Temporal Patterns Of Precipitation And Temperature At Various Time Scales In North Korea, Won-Ho Nam, Eun-Mi Hong, Guillermo A. Baigorria

Papers in Natural Resources

Detecting changes in the spatio-temporal patterns of temperature and precipitation is a prerequisite for developing effective adaptation options and strategies for the future. An effective method for assessing climate change and for providing information to decision makers and stakeholders is needed to implement appropriate adaptation strategies. The objective of this study was to determine whether climate change has caused spatio-temporal changes in meteorological elements in North Korea. We delineated the spatio-temporal patterns of temperature and precipitation caused by climate change in specific time periods based on statistically significant differences using a statistically robust method. Historical weather data from 27 meteorological …

Phycocyanin-Specific Absorption Coefficient: Eliminating The Effect Of Chlorophylls Absorption, Y. Z. Yacobi, J. Köhler, F. Leunert, Anatoly A. Gitelson

Papers in Natural Resources

The applicability of algorithms for estimation of phycocyanin (PC) concentration based on light spectral reflectance heavily depends on the specific absorption of the pigment. But the determination of PC-specific absorption coefficient is not a straightforward task, as PC optical activity is overlapped by absorption of chlorophylls. The aim of our study was to determine a*_PC(625)—the specific absorption coefficient of PC at 625 nm, in samples with PC concentrations ranging from 0.5 mg m^-3 to 126.4 mg m^-3 and varying proportions of chlorophylls a, b, and c in the samples. The effect of chlorophylls was subtracted from …

Application Of Remote Sensing For Quantifying And Mapping Surface Energy Fluxes In South Central Nebraska: Analyses With Respect To Field Measurements, Vivek Sharma, Suat Irmak, Ayse Kilic, Denis Mutibwa

Papers in Natural Resources

Large-scale quantification of crop evapotranspiration (ETc) from various vegetation surfaces can aid in planning, managing, and allocating water resources. Field measurement of surface energy fluxes, including ETc, remains (and should remain) a crucial process for calibration and validation of satellite/remote sensing-based methods, which can provide important supporting information for water balance assessments and for analyzing the spatial distribution of energy fluxes on large scales. The Surface Energy Balance System (SEBS) was evaluated in estimating surface energy fluxes in south central Nebraska using Landsat imagery and meteorological data. SEBS-estimated surface energy fluxes were compared to Bowen Ratio Energy Balance System (BREBS) …

Habitat Characteristics Of Eastern Wild Turkey Nest And Ground-Roost Sites In 2 Longleaf Pine Forests, Mary M. Streich, Andrew R. Little, Michael J. Chamberlain, L. Mike Connor, Robert J. Warren

Papers in Natural Resources

Managing and restoring longleaf pine forests throughout the Southeast is a conservation priority. Prescribed fire is an integral part of these activities, as it is the primary means of controlling hardwood encroachment and maintaining native groundcover. Nest site and preflight brood groundroost site selection of eastern wild turkeys (Meleagris gallopavo silvestris) has not been well studied in longleaf pine systems. Therefore, we determined habitat characteristics associated with wild turkey nests and ground-roosts in 2 longleaf pine forests in southwestern Georgia. We radio-tagged 45 female turkeys and evaluated habitat characteristics associated with 84 nests and 51 ground-roosts during the …

Estimation And Analysis Of Gross Primary Production Of Soybean Under Various Management Practices And Drought Conditions, Pradeep Wagle, Xiangming Xiao, Andrew E. Suyker

Papers in Natural Resources

Gross primary production (GPP) of croplands may be used to quantify crop productivity and evaluate a range of management practices. Eddy flux data from three soybean (Glycine max L.) fields under different management practices (no-till vs. till; rainfed vs. irrigated) and Moderate Resolution Imaging Spectroradiometer (MODIS) derived vegetation indices (VIs) were used to test the capabilities of remotely sensed VIs and soybean phenology to estimate the seasonal dynamics of carbon fluxes. The modeled GPP (GPP_VPM) using vegetation photosynthesis model (VPM) was compared with the GPP (GPP_EC) estimated from eddy covariance measurements. The VIs tracked soybean …

Factors Affecting Female Space Use In Ten Populations Of Prairie Chickens, Virginia L. Winder, Kaylan M. Carrlson, Andrew J. Gregory, Christian A. Hagen, David A. Haukos, Dylan C. Kesler, Lena C. Larsson, Ty W. Matthews, Lance B. Mcnew, Michael A. Patten, Jim C. Pitman, Larkin A. Powell, Jennifer A. Smith, Tom Thompson, Donald H. Wolfe, Brett K. Sandercock

Papers in Natural Resources

Conservation of wildlife depends on an understanding of the interactions between animal

movements and key landscape factors. Habitat requirements of wide-ranging species often vary spatially,

but quantitative assessment of variation among replicated studies at multiple sites is rare. We investigated

patterns of space use for 10 populations of two closely related species of prairie grouse: Greater Prairie-

Chickens (Tympanuchus cupido) and Lesser Prairie-Chickens (T. pallidicinctus). Prairie chickens require large,

intact tracts of native grasslands, and are umbrella species for conservation of prairie ecosystems in North

America. We used resource utilization functions to investigate space use by female prairie chickens during …

Thermal-Based Modeling Of Coupled Carbon, Water, And Energy Fluxes Using Nominal Light Use Efficiencies Constrained By Leaf Chlorophyll Observations, M. A. Schull, M. C. Anderson, R. Houborg, Anatoly A. Gitelson, W. P. Kustas

Papers in Natural Resources

Recent studies have shown that estimates of leaf chlorophyll content (Chl), defined as the combined mass of chlorophyll a and chlorophyll b per unit leaf area, can be useful for constraining estimates of canopy light use efficiency (LUE). Canopy LUE describes the amount of carbon assimilated by a vegetative canopy for a given amount of absorbed photosynthetically active radiation (APAR) and is a key parameter for modeling land-surface carbon fluxes. A carbonenabled version of the remote-sensing-based two-source energy balance (TSEB) model simulates coupled canopy transpiration and carbon assimilation using an analytical submodel of canopy resistance constrained by inputs of nominal …

Fish-Protection Devices At Unscreened Water Diversions Can Reduce Entrainment: Evidence From Behavioural Laboratory Investigations, Jamilynn B. Poletto, Dennis E. Cocherell, Timothy D. Mussen, Ali Ercan, Hossein Bandeh, M. Levent Kavvas, Joseph J. Cech Jr., Nann A. Fangue

Papers in Natural Resources

Diversion (i.e. extraction) of water from rivers and estuaries can potentially affect native wildlife populations if operation is not carefully managed. For example, open, unmodified water diversions can act as a source of injury or mortality to resident or migratory fishes from entrainment and impingement, and can cause habitat degradation and fragmentation. Fish-protection devices, such as exclusion screens, louvres or sensory deterrents, can physically or behaviourally deter fish from approaching or being entrained into water diversions. However, empirical assessment of their efficacy is often lacking or is investigated only for particular economically or culturally important fishes, such as salmonids. The …

An Anomaly-Based Method For Identifying Signals Of Spring And Autumn Low-Temperature Events In The Yangtze River Valley, China, Weihong Qian, Yun Cheng, Man Jiang, Qi Hu

Papers in Natural Resources

June 2015 QIAN ET AL. Vol. 54 1216-1233

Fitting Measured Evapotranspiration Data To The Fao56 Dual Crop Coefficient Method, R G. Allen, Ayse Kilic, Andrew Suyker, Jane A. Okalebo

Papers in Natural Resources

The FAO-56 publication of the UN Food and Agriculture Organization contains guidelines on constructing and applying a ‘dual crop coefficient’ method to characterize the behavior of evapotranspiration (ET) on a day to day basis. The dual crop coefficient (Kc) method substantially improves the ability to fit simulated with measured data, as compared to the ‘single’ Kc method, by partitioning evaporation from soil (Es) from transpiration from vegetation. This permits the separate estimation of Es when there are known wetting events from precipitation and irrigation and assists in explaining behavior of measured data. The application of the dual Kc method is …

Accountability In Networked Governance: Learning From A Case Of Landscape-Scale Forest Conservation, Theresa Jedd, R. Patrick Bixler

Papers in Natural Resources

No abstract provided.

The Importance Of Lake-Specific Characteristics For Water Quality Across The Continental United States, Emily K. Read, Vijay P. Patil, Samantha K. Oliver, Amy L. Hetherington, Jennifer A. Brentrup, Jacob A. Zwart, Kirsten M. Winters, Jessica R. Corman, Emily R. Nodine, R. Iestyn Woolway, Hilary A. Dugan, Aline Jaimes, Arianto B. Santoso, Grace S. Hong, Luke A. Winslow, Paul C. Hanson, Kathleen C. Weathers

Papers in Natural Resources

Lake water quality is affected by local and regional drivers, including lake physical characteristics, hydrology, landscape position, land cover, land use, geology, and climate. Here, we demonstrate the utility of hypothesis testing within the landscape limnology framework using a random forest algorithm on a national-scale, spatially explicit data set, the United States Environmental Protection Agency’s 2007 National Lakes Assessment. For 1026 lakes, we tested the relative importance of water quality drivers across spatial scales, the importance of hydrologic connectivity in mediating water quality drivers, and how the importance of both spatial scale and connectivity differ across response variables for five …

A Global Perspective On Wetland Salinization: Ecological Consequences Of A Growing Threat To Freshwater Wetlands, Ellen R. Herbert, Paul Boon, Amy J. Burgin, Scott C. Neubauer, Rima B. Franklin, Marcelo Ardón, Kristine N. Hopfensperger, Leon P.M. Lamers, Peter Gell

Papers in Natural Resources

Salinization, a widespread threat to the structure and ecological functioning of inland and coastal wetlands, is currently occurring at an unprecedented rate and geographic scale. The causes of salinization are diverse and include alterations to freshwater flows, land-clearance, irrigation, disposal of wastewater effluent, sea level rise, storm surges, and applications of de-icing salts. Climate change and anthropogenic modifications to the hydrologic cycle are expected to further increase the extent and severity of wetland salinization. Salinization alters the fundamental physicochemical nature of the soil-water environment, increasing ionic concentrations and altering chemical equilibria and mineral solubility. Increased concentrations of solutes, especially sulfate, …

The Uncertain Climate Footprint Of Wetlands Under Human Pressure, Ana Maria Roxana Petrescu, Annalea Lohila, Juha-Pekka Tuovinen, Dennis D. Baldocchi, Ankur R. Desai, Nigel T. Roulet, Timo Vesala, Albertus Johannes Dolman, Walter C. Oechel, Barbara Marcolla, Thomas Friborg, Janne Rinne, Jaclyn Hatala Matthes, Lutz Merbold, Ana Meijide, Gerard Kiely, Matteo Sottocornola, Torsten Sachs, Donatella Zona, Andrej Varlagin, Derrick Y.F. Lai, Elmar Veenendaal, Frans-Jan W. Parmentier, Ute Skiba, Magnus Land, Arjan Hensen, Jacobus Van Huissteden, Lawrence B. Flanagan, Narasinha J. Shurpali, Thomas Grünwald, Elyn R. Humphreys, Marcin Jackowicz-Korczynski, Mika A. Aurela, Tuomas Laurila, Carsten Grüning, Chiara A.R. Corradi, Arina P. Schrier-Uijl, Torben R. Christensen, Mikkel P. Tamstorf, Mikhail Mastepanov, Pertti J. Martikainen, Shashi Verma, Christian Bernhofer, Alessandro Cescatti

Papers in Natural Resources

Significant climate risks are associated with a positive carbon–temperature feedback in northern latitude carbon-rich ecosystems,making an accurate analysis of human impacts on the net greenhouse gas balance of wetlands a priority. Here, we provide a coherent assessment of the climate footprint of a network of wetland sites based on simultaneous and quasi-continuous ecosystem observations of CO₂ and CH₄ fluxes. Experimental areas are located both in natural and in managed wetlands and cover a wide range of climatic regions, ecosystem types, and management practices. Based on direct observations we predict that sustained CH₄ emissions in natural ecosystems are …

Remote Sensing Of Drought: Progress, Challenges And Opportunities, A. Aghakouchak, A. Farahmand, F. S. Melton, J. Teixeira, M. C. Anderson, Brian D. Wardlow, C. R. Hain

Papers in Natural Resources

This review surveys current and emerging drought monitoring approaches using satellite remote sensing observations from climatological and ecosystem perspectives. We argue that satellite observations not currently used for operational drought monitoring, such as near-surface air relative humidity data from the Atmospheric Infrared Sounder mission, provide opportunities to improve early drought warning. Current and future satellite missions offer opportunities to develop composite and multi-indicator drought models. While there are immense opportunities, there are major challenges including data continuity, unquantified uncertainty, sensor changes, and community acceptability. One of the major limitations of many of the currently available satellite observations is their short …

Complementary-Relationship-Based 30 Year Normals (1981–2010) Of Monthly Latent Heat Fluxes Across The Contiguous United States, Jozsef Szilagyi

Papers in Natural Resources

Thirty year normal (1981–2010) monthly latent heat fluxes (ET) over the conterminous United States were estimated by a modified Advection-Aridity model from North American Regional Reanalysis (NARR) radiation and wind as well as Parameter-Elevation Regressions on Independent Slopes Model (PRISM) air and dew-point temperature data. Mean annual ET values were calibrated with PRISM precipitation (P) and validated against United States Geological Survey runoff (Q) data. At the six-digit Hydrologic Unit Code level (sample size of 334) the estimated 30 year normal runoff (P – ET) had a bias of 18 mm yr^-1, a root-mean-square error of …

Evaluating Recreationists’ Awareness And Attitudes Toward Piping Plovers (Charadrius Melodus) At Lake Mcconaughy, Nebraska, Usa, Joel G. Jorgensen, Mary Bomberger Brown

Papers in Natural Resources

Piping plovers (Charadrius melodus) are shorebirds federally protected by the U.S. Endangered Species Act that often nest on beaches in proximity to human recreation. We evaluated whether awareness of piping plovers and their legally protected status and attitudes toward species management varied between groups of recreationists at Lake McConaughy, Keith County, Nebraska, USA. Awareness of piping plovers varied primarily by the respondents’ number of annual visits to Lake McConaughy; the respondents’ age, sex, or location of primary residence had less influence. Recreationists with increased awareness of piping plovers and their protected status did not have more favorable attitudes toward plovers …

The Need For A Common Basis For Defining Light-Use Efficiency: Implications For Productivity Estimation, Anatoly A. Gitelson, John A. Gamon

Papers in Natural Resources

A primary focus of this short communication is to show how the operational definition of light use efficiency (LUE) influences the results and interpretation of the LUE model. Our study was motivated by the observation that multiple LUE definitions are reported in the literature. The temporal behavior of three operational definitions of LUE, based on (i) incident radiation, (ii) total absorbed radiation and (iii) radiation absorbed by photosynthetically active/green vegetation was examined for two contrasting crops (soybean and maize) having different physiologies, leaf structures and canopy architectures. Over the course of a growing season, the behavior of these three contrasting …

Simultaneous Cr(Vi) Reduction And Methylene Blue Removal By Bacillus Sp. Jh2-2 Isolated From Mining Site Soil, Jaehong Shim, Patrick Shea, Jeong-Muk Lim, Byung-Taek Oh

Papers in Natural Resources

A Bacillus sp. strain (JH2-2), isolated from soil at an abandoned mine site, reduced Cr(VI) to Cr(III) under aerobic conditions. At pH 7, the strain reduced essentially all of the Cr(VI) in M9 minimal medium to Cr(III) at initial concentrations ≤50 mg Cr(VI) L⁻¹ within 100 h. The X-ray diffraction pattern of the Cr(III) precipitate matched chromium (III) hydrogen phosphate (CrH₂P₃O₁₀∙2H₂O). The JH2-2 strain showed high tolerance to other heavy metal (loid)s, with minimal inhibitory concentrations in liquid medium of (mg L−1): As (500), Cd (100), Cu (350), Ni (300), Zn …

Professional Development At The Local Level: Necessary And Sufficient Conditions For Critical Colleagueship, Tara Kintz, John Lane, Amelia Gotwals, Dante Cisterna

Papers in Natural Resources

No abstract provided.

The Accumulated Winter Season Severity Index (Awssi), Barbara E. Mayes Boustead, Steven D. Hilberg, Martha Shulski, Kenneth Hubbard

Papers in Natural Resources

The character of a winter can be defined by many of its features, including temperature averages and extremes, snowfall totals, snow depth, and the duration between onset and cessation of winter-weather conditions. The accumulated winter season severity index incorporates these elements into one site-specific value that defines the severity of a particular winter, especially when examined in the context of climatological values for that site. Thresholds of temperature, snowfall, and snow depth are assigned points that accumulate through the defined winter season; a parallel index uses temperature and precipitation to provide a snow proxy where snow data are unavailable or …