Physical Sciences and Mathematics Commons^™

Coupling Dendroecological And Remote Sensing Techniques To Assess The Biophysical Traits Of Juniperus Virginiana And Pinus Ponderosa Within The Semi-Arid Grasslands Of The Nebraska Sandhills, R. Allen, Anastasios Mazis, Brian Wardlow, P. Cherubini, J. Hiller, David A. Wedin, Tala Awada

School of Natural Resources: Faculty Publications

Woody species encroachment is occurring within the semi-arid grasslands of the Nebraska Sandhills U.S., primarily driven by native Juniperus virginiana and Pinus ponderosa, altering ecosystems and the services they provide. Effective, low cost, and cross-scale monitoring of woody species growth and performance is necessary for integrated grassland and forest management in the face of climate variability and change. In this study, we sought to establish a relationship between remote sensing-derived vegetation indices (VIs), tree dendrochronological (raw and standardized tree ring width) measurements, and the abiotic environment [(precipitation, temperature, Palmer Drought Severity Index (PDSI), and soil water content (0–300 cm …

Revisiting The Carbon–Biodiversity Connection, John Gamon

School of Natural Resources: Faculty Publications

This article is a Commentary on Schuldt et al., https://doi.org/10.1111/gcb.16697

The link between biodiversity and ecosystem function has long been a subject of intense interest and debate among biologists, going back to the time of Charles Darwin, whose ideas on species interactions presaged subsequent discussions of biodiversity and ecosystem function (Peterson et al., 1998). Since then, many considerations of community diversity have centered on the importance of species or functional diversity for maintaining system resilience in the face of disturbance, analogous to the way that interwoven threads maintain the function and integrity of fabric. While our language, concepts, and methods …

Assessment Of An Evapotranspiration Algorithm Accounting For Land Cover Types And Photosynthetic Perspectives Using Remote Sensing Images, C. Sur, W. H. Nam, X. Zhang, Tsegaye Tadesse, Brian D. Wardlow

School of Natural Resources: Faculty Publications

No abstract provided.

Canopy Spectral Reflectance Detects Oak Wilt At The Landscape Scale Using Phylogenetic Discrimination, Gerard Sapes, Cathleen Lapadat, Anna K. Schweiger, Jennifer Juzwik, Rebecca Montgomery, Hamed Gholizadeh, Philip A. Townsend, John A. Gamon, Jeannine Cavender-Bares

School of Natural Resources: Faculty Publications

The oak wilt disease caused by the invasive fungal pathogen Bretziella fagacearum is one of the greatest threats to oak-dominated forests across the Eastern United States. Accurate detection and monitoring over large areas are necessary for management activities to effectively mitigate and prevent the spread of oak wilt. Canopy spectral reflectance contains both phylogenetic and physiological information across the visible near-infrared (VNIR) and short-wave infrared (SWIR) ranges that can be used to identify diseased red oaks. We develop partial least square discriminant analysis (PLS-DA) models using airborne hyperspectral reflectance to detect diseased canopies and assess the importance of VNIR, SWIR, …

Groundwater Level Assessment And Prediction In The Nebraska Sand Hills Using Lidar-Derived Lake Water Level, Nawaraj Shrestha, Aaron R. Mittelstet, Aaron R. Young, Troy E. Gilmore, David C. Gosselin, Yi Qi, Caner Zeyrek

School of Natural Resources: Faculty Publications

The spatial variability of groundwater levels is often inferred from sparsely located hydraulic head observations in wells. The spatial correlation structure derived from sparse observations is associated with uncertainties that spread to estimates at unsampled locations. In areas where surface water represents the nearby groundwater level, remote sensing techniques can estimate and increase the number of hydraulic head measurements. This research uses light detection and ranging (LIDAR) to estimate lake surface water level to characterize the groundwater level in the Nebraska Sand Hills (NSH), an area with few observation wells. The LIDAR derived lake groundwater level accuracy was within 40 …

Aquatic Habitat Changes Within The Channelized And Impounded Arkansas River, Arkansas, Usa, Jonathan J. Spurgeon, Mike Rhodes, J. Wesley Neal, Kristine O. Evans

School of Natural Resources: Faculty Publications

River-wide changes in morphologic character following channelization and impoundment alter the occurrence and distribution of surface water and available habitats for aquatic organisms. Quantifying patterns of creation, redistribution or disappearance of habitats at river-wide and decadal spatiotemporal scales can promote understanding regarding trajectories of different habitat types following alteration and prospects of direct habitat enhancement projects within altered alluvial rivers. Newly available remote-sensing tools and databases may improve detection of river-wide changes in habitat through time. We used a combination of remote-sensing data and generalized linear models to assess changes in surface water coverage from 1984 to 2015 among aquatic …

Remote Sensing And Three-Dimensional Photogrammetric Analysis Of Glaciofluvial Sand And Gravel Deposits For Aggregate Resource Assessment In Mchenry County, Illinois, Usa, Xiaodong Miao, Christopher J. Stohr, Paul R. Hanson, Qiansuo Wang

School of Natural Resources: Faculty Publications

Sand and gravel deposits, one of the most common natural resources, are used as aggregates mostly by the construction industry, and their extraction contributes significantly to a region's economy. Thus, it is critical to locate sand and gravel deposits, and evaluate their quantity and quality safely and quickly. However, information on aggregate resources is generally only available from conventional two-dimensional (2-D) geologic maps, and direct field measurements for quality analysis at outcrops are time consuming and are often not possible due to safety concerns, or simply because exposures are too difficult to access. In this study, we presented a methodology …

Leaf Reflectance Spectra Capture The Evolutionary History Of Seed Plants, Jose Eduardo Meireles, Jeannine Cavender-Bares, Philip A. Townsend, Susan Ustin, John A. Gamon, Anna K. Schweiger, Michael E. Schaepman, Gregory P. Asner, Roberta E. Martin, Aditya Singh, Franziska Schrodt, Adam Chlus, Brian C. O’Meara

School of Natural Resources: Faculty Publications

• Leaf reflection spectra have been increasingly used to assess plant diversity. However, we do not yet understand how spectra vary across the tree of life or how the evolution of leaf traits affects the differentiation of spectra among species and lineages.
• Here we describe a framework that integrates spectra with phylogenies and apply it to aglobal dataset of over 16 000 leaf-level spectra (400–2400 nm) for 544 seed plant species. We test for phylogenetic signal in spectra, evaluate their ability to classify lineages, and characterize their evolutionary dynamics.
• We show that phylogenetic signal is present in leaf spectra but that …

Czech Drought Monitor System For Monitoring And Forecasting Of Agricultural Drought And Drought Impacts, Miroslav Trnka, Petr Hlavinka, Martin Možný, Daniela Semerádová, Petr Štěpánek, Jan Balek, Lenka Bartošová, Pavel Zahradníček, Monika Bláhová, Petr Skalák, Aleš Farda, Michael Hayes, Mark D. Svoboda, Wolfgang Wagner, Josef Eitzinger, Milan Fischer, Zdeněk Zalud

School of Natural Resources: Faculty Publications

The awareness of drought and its impacts on Central Europe increased after the significant drought episodes in 2000, 2003, 2012 and 2015, which were all estimated to have caused over 500 million Euro in damage in the Czech Republic alone. These events indicated the need for timely and highresolution monitoring tools that would enable analysing, monitoring and forecasting of drought events. Monitoring soil water availability in near real time and at high-resolution (up to 0.5 × 0.5 km for some products) helps farmers and water managers to mitigate impacts of these extreme events. The Czech Drought Monitor was developed between …

A Review Of Drought Monitoring Using Remote Sensing And Data Mining Methods, R. Inoubli, A.B. Abbes, I.R. Farah, V. Singh, T. Tadesse, A.Z. Abiy

School of Natural Resources: Faculty Publications

No abstract provided.

Beyond Inventories: Emergence Of A New Era In Rangeland Monitoring, Matthew O. Jones, David E. Naugle, Dirac Twidwell, Daniel R. Uden, Jeremy D. Maestas, Brady W. Allred

School of Natural Resources: Faculty Publications

In the absence of technology-driven monitoring platforms, US rangeland policies, management practices, and outcome assessments have been primarily informed by the extrapolation of local information from national-scale rangeland inventories. A persistent monitoring gap between plot-level inventories and the scale at which rangeland assessments are conducted has required decision makers to fill data gaps with statistical extrapolations or assumptions of homogeneity and equilibrium. This gap is now being bridged with spatially comprehensive, annual, rangeland monitoring data across all western US rangelands to as- sess vegetation conditions at a resolution appropriate to inform cross-scale assessments and decisions. In this paper, 20-yr trends …

Current Frameworks For Reference Et And Crop Coefficient Calculation, R G. Allen, Ayse Kilic, Clarence W. Robison

School of Natural Resources: Faculty Publications

Estimation of evapotranspiration is under continual development and evolution, with significant developments and standardizations made during the past three decades for both reference ET (ETref) and for crop coefficients (Kc). These standardizations provide consistency and reproducibility in estimating ETref and a consistent basis for determining and expressing Kc curves, especially at the local scale. The application of the dual Kc procedure is growing, and has strong potential for improving accuracy of ET estimates as compared to the single Kc approach. This article describes current structures for estimating crop coefficients including the standardized FAO-56 dual Kc approach, with example applications. Emphasis …

Metric-Gis: An Advanced Energy Balance Model For Computing Crop Evapotranspiration In A Gis Environment, J. M. Ramírez-Cuesta, R G. Allen, D. S. Intrigliolo, Ayse Kilic, Clarence W. Robison, Ricardo Trezza, C. Santos, I. J. Lorite

School of Natural Resources: Faculty Publications

A novel ArcGIS toolbox that applies the Mapping Evapotranspiration with Internalized Calibration model was developed and tested in a semi-arid environment. The tool, named METRIC-GIS, facilitates the pre-processing operations and the automatic identification of potential calibration and pixels review. The energy balance components obtained from METRIC-GIS were contrasted with those from the original METRIC version (R² = 1; RMSE = 0 W m^–2 or mm day^–1 for ET_c) Additionally, an irrigated scheme located at southern Spain was considered for assessing Kc variability in the maize fields with METRIC-GIS. The identified spatial variability was mainly due …

A Review Of Vegetation Phenological Metrics Extraction Using Time-Series, Multispectral Satellite Data, Linglin Zeng, Brian D. Wardlow, Daxiang Xiang, Shun Hu, Deren Li

School of Natural Resources: Faculty Publications

Vegetation dynamics and phenology play an important role in inter-annual vegetation changes in terrestrial ecosystems and are key indicators of climate-vegetation interactions, land use/land cover changes, and variation in year-to-year vegetation productivity. Satellite remote sensing data have been widely used for vegetation phenology monitoring over large geographic domains using various types of observations and methods over the past several decades. The goal of this paper is to present a detailed review of existing methods for phenology detection and emerging new techniques based on the analysis of time-series, multispectral remote sensing imagery. This paper summarizes the objective and applications of detecting …

The Role Of Topography, Soil, And Remotely Sensed Vegetation Condition Towards Predicting Crop Yield, Trenton E. Franz, Sayli Pokal, Justin P. Gibson, Yuzhen Zhou, Hamed Gholizadeh, Fatima Amor Tenorio, Daran Rudnick, Derek M. Heeren, Matthew F. Mccabe, Matteo Ziliani, Zhenong Jin, Kaiyu Guan, Ming Pan, John Gates, Brian Wardlow

School of Natural Resources: Faculty Publications

Foreknowledge of the spatiotemporal drivers of crop yield would provide a valuable source of information to optimize on-farm inputs and maximize profitability. In recent years, an abundance of spatial data providing information on soils, topography, and vegetation condition have become available from both proximal and remote sensing platforms. Given the wide range of data costs (between USD $0−50/ha), it is important to understand where often limited financial resources should be directed to optimize field production. Two key questions arise. First, will these data actually aid in better fine-resolution yield prediction to help optimize crop management and farm economics? Second, what …

The Spatial Sensitivity Of The Spectral Diversity–Biodiversity Relationship: An Experimental Test In A Prairie Grassland, Ran Wang, John A. Gamon, Jeannine Cavender-Bares, Philip A. Townsend, Arthur I. Zygielbaum

School of Natural Resources: Faculty Publications

Remote sensing has been used to detect plant biodiversity in a range of ecosystems based on the varying spectral properties of different species or functional groups. However, the most appropriate spatial resolution necessary to detect diversity remains unclear. At coarse resolution, differences among spectral patterns may be too weak to detect. In contrast, at fine resolution, redundant information may be introduced. To explore the effect of spatial resolution, we studied the scale dependence of spectral diversity in a prairie ecosystem experiment at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Our study involved a scaling exercise comparing synthetic pixels resampled from …

The Spatial Sensitivity Of The Spectral Diversity–Biodiversity Relationship: An Experimental Test In A Prairie Grassland, Ran Wang, John A. Gamon, Jeannine Cavender-Bares, Philip A. Townsend, Arthur I. Zygielbaum

School of Natural Resources: Faculty Publications

Remote sensing has been used to detect plant biodiversity in a range of ecosystems based on the varying spectral properties of different species or functional groups. However, the most appropriate spatial resolution necessary to detect diversity remains unclear. At coarse resolution, differences among spectral patterns may be too weak to detect. In contrast, at fine resolution, redundant information may be introduced. To explore the effect of spatial resolution, we studied the scale dependence of spectral diversity in a prairie ecosystem experiment at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Our study involved a scaling exercise comparing synthetic pixels resampled from …

Informative Spectral Bands For Remote Green Lai Estimation In C3 And C4 Crops, Oz Kira, Anthony L. Nguy-Robertson, Timothy J. Arkebauer, Raphael Linker, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

Green leaf area index (LAI) provides insight into the productivity, physiological and phenological status of vegetation. Measurement of spectral reflectance offers a fast and nondestructive estimation of green LAI. A number of methods have been used for the estimation of green LAI; however, the specific spectral bands employed varied widely among the methods and data used. Our objectives were (i) to find informative spectral bands retained in three types of methods, neural network (NN), partial least squares (PLS) regression and vegetation indices (VI), for estimating green LAI in maize (a C4 species) and soybean (a C3 species); (ii) to assess …

Integrated Analysis Of Productivity And Biodiversity In A Southern Alberta Prairie, Ran Wang, John A. Gamon, Craig A. Emmerton, Haitao Li, Enrica Nestola, Gilberto Z. Pastorello, Olaf Menzer

School of Natural Resources: Faculty Publications

Grasslands play important roles in ecosystem production and support a large farming and grazing industry. An accurate and efficient way is needed to estimate grassland health and production for monitoring and adjusting management to get sustainable products and other ecosystem services. Previous studies of grasslands have shown varying relationships between productivity and biodiversity, with most showing either a positive or a hump-shaped relationship where productivity peaks at intermediate diversity. In this study, we used airborne imaging spectrometry combined with ground sampling and eddy covariance measurements to estimate the spatial pattern of production and biodiversity for two sites of contrasting productivity …

Seasonal Variation In The Ndvi–Species Richness Relationship In A Prairie Grassland Experiment (Cedar Creek), Ran Wang, John A. Gamon, Rebecca A. Montgomery, Philip A. Townsend, Arthur I. Zygielbaum, Keren Bitan, David Tilman, Jeannine Cavender-Bares

School of Natural Resources: Faculty Publications

Species richness generally promotes ecosystem productivity, although the shape of the relationship varies and remains the subject of debate. One reason for this uncertainty lies in the multitude of methodological approaches to sampling biodiversity and productivity, some of which can be subjective. Remote sensing offers new, objective ways of assessing productivity and biodiversity. In this study, we tested the species richness–productivity relationship using a common remote sensing index, the Normalized Difference Vegetation Index (NDVI), as a measure of productivity in experimental prairie grassland plots (Cedar Creek). Our study spanned a growing season (May to October, 2014) to evaluate dynamic changes …

Estimation Of Energy Balance Components Over A Drip-Irrigated Olive Orchard Using Thermal And Multispectral Cameras Placed On A Helicopter-Based Unmanned Aerial Vehicle (Uav), Samuel Ortega-Farias, Samuel Ortega-Salazar, Tomas Poblete, Ayse Kilic, Richard Allen, Carlos Poblete-Echeverria, Luis Ahumada-Orellana, Mauricio Zuniga, Daniel Sepulveda

School of Natural Resources: Faculty Publications

A field experiment was carried out to implement a remote sensing energy balance (RSEB) algorithm for estimating the incoming solar radiation (Rsi), net radiation (Rn), sensible heat flux (H), soil heat flux (G) and latent heat flux (LE) over a drip-irrigated olive (cv. Arbequina) orchard located in the Pencahue Valley, Maule Region, Chile (35^◦25'S; 71^◦44'W; 90 m above sea level). For this study, a helicopter-based unmanned aerial vehicle (UAV) was equipped with multispectral and infrared thermal cameras to obtain simultaneously the normalized difference vegetation index (NDVI) and surface temperature (Tsurface) at very high resolution (6 cm …

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

School of Natural Resources: Faculty Publications

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, …

Eeflux: A Landsat-Based Evapotranspiration Mapping Tool On The Google Earth Engine, Richard Allen, Charles Morton, Baburao Kamble, Ayse Kilic, Justin Huntington, David Thau, Noel Gorelick, Tyler Erickson, Rebecca Moore, Ricardo Trezza, Ian C. Ratcliffe, Clarence Robison

School of Natural Resources: Faculty Publications

“EEFlux” is an acronym for ‘Earth Engine Evapotranspiration Flux.’ EEFlux is based on the operational surface energy balance model “METRIC” (Mapping ET at high Resolution with Internalized Calibration), and is a Landsat-imagebased process. Landsat imagery supports the production of ET maps at resolutions of 30 m, which is the scale of many human-impacted and human-interest activities including agricultural fields, forest clearcuts and vegetation systems along streams. ET over extended time periods provides valuable information regarding impacts of water consumption on Earth resources and on humans. EEFlux uses North American Land Data Assimilation System hourly gridded weather data collection for energy …

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

School of Natural Resources: Faculty Publications

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) …

Multi-Scale Evaluation Of Light Use Efficiency In Modis Gross Primary Productivity For Croplands In The Midwestern United States, Qinchuan Xin, Mark Broich, Andrew E. Suyker, Le Yu, Peng Gong

School of Natural Resources: Faculty Publications

Satellite remote sensing provides continuous observations of land surfaces, thereby offering opportunities for large-scale monitoring of terrestrial productivity. Production Efficiency Models (PEMs) have been widely used in satellite-based studies to simulate carbon exchanges between the atmosphere and ecosystems. However, model parameterization of the maximum light use efficiency (ε*_GPP) varies considerably for croplands in agricultural studies at different scales. In this study, we evaluate cropland ε*_GPP in the MODIS Gross Primary Productivity (GPP) model (MOD17) using in situ measurements and inventory datasets across the Midwestern US. The site-scale calibration using 28 site-years tower measurements derives ε*_GPP values …

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

School of Natural Resources: Faculty Publications

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 …

Monitoring Live Fuel Moisture Using Soil Moisture And Remote Sensing Proxies, Yi Qi, Philip E. Dennison, Jessica Spencer, David Riano

School of Natural Resources: Faculty Publications

Live fuel moisture (LFM) is an important fuel property controlling fuel ignition and fire propagation. LFM varies seasonally, and is controlled by precipitation, soil moisture, evapotranspiration, and plant physiology. LFM is typically sampled manually in the field, which leads to sparse measurements in space and time. Use of LFM proxies could reduce the need for field sampling while potentially improving spatial and temporal sampling density. This study compares soil moisture and remote sensing data to field-sampled LFM for Gambel oak (Quercus gambelii Nutt) and big sagebrush (Artemisia tridentata Nutt) in northern Utah. Bivariate linear regression models were constructed …

Nir-Red Reflectance-Based Algorithms For Chlorophyll-A Estimation In Mesotrophic Inland And Coastal Waters: Lake Kinneret Case Study, Yosef Z. Yacobi, Wesley Moses, Semion Kaganovsky, Benayahu Sulimani, Bryan Leavitt, Anatoly A. Gitelson

School of Natural Resources: Faculty Publications

A variety of models have been developed for estimating chlorophyll-a (Chl-a) concentration in turbid and productive waters. All are based on optical information in a few spectral bands in the red and near-infra-red regions of the electromagnetic spectrum. The wavelength locations in the models used were meticulously tuned to provide the highest sensitivity to the presence of Chl-a and minimal sensitivity to other constituents in water. But the caveat in these models is the need for recurrent parameterization and calibration due to changes in the biophysical characteristics of water based on the location and/or time of the year. In this …

Spectral Data-Based Estimation Of Soil Heat Flux, Ramesh K. Singh, Ayse Kilic, Elizabeth Walter-Shea, Shashi B. Verma, Andrew E. Suyker

School of Natural Resources: Faculty Publications

Numerous existing spectral‐based soil heat flux (G) models have shown wide variation in performance for maize and soybean cropping systems in Nebraska, indicating the need for localized calibration and model development. The objectives of this article are to develop a semi‐empirical model to estimate G from a normalized difference vegetation index (NDVI) and net radiation (R_n) for maize (Zea mays L.) and soybean (Glycine max L.) fields in the Great Plains, and present the suitability of the developed model to estimate G under similar and different soil and management conditions. Soil heat fluxes measured in both …