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School of Natural Resources: Faculty Publications

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Articles 1381 - 1410 of 1586

Full-Text Articles in Physical Sciences and Mathematics

Optical Properties Of Canopy Elements In Black Spruce, Jack Pine And Aspen Stands In Saskatchewan, Canada, Elizabeth A. Walter-Shea, Mark A. Mesarch Jan 1998

Optical Properties Of Canopy Elements In Black Spruce, Jack Pine And Aspen Stands In Saskatchewan, Canada, Elizabeth A. Walter-Shea, Mark A. Mesarch

School of Natural Resources: Faculty Publications

No abstract provided.

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Unique Frontal Sinuses In Fossil And Living Hyaenidae (Mammalia, Carnivora): Description And Interpretation, R.M. Joeckel Jan 1998

Unique Frontal Sinuses In Fossil And Living Hyaenidae (Mammalia, Carnivora): Description And Interpretation, R.M. Joeckel

School of Natural Resources: Faculty Publications

No abstract provided.

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Assessment Of Urban Heat Islands: A Multi-Sensor Perspective For The Dallas-Ft. Worth, Usa Region, Kevin P. Gallo, Timothy W. Owen Jan 1998

Assessment Of Urban Heat Islands: A Multi-Sensor Perspective For The Dallas-Ft. Worth, Usa Region, Kevin P. Gallo, Timothy W. Owen

School of Natural Resources: Faculty Publications

Data acquired during the early to mid-1990s by several satellite-sensor systems were combined in an assessment of the urban heat-island effect for the Dallas-Fort Worth, TX region of the United States. Normalized difference vegetation index and radiant surface temperature were computed from NOAA-AVHRR data. Two measures of the anthropogenic light emitted by urban-related surface features were available from the DMSP-OLS. Landsat MSS data were used to provide estimates of the predominant land cover within the grid cells associated with the NOA-AVHRR and DMSP-OLS data. The multi-sensor analysis of the environment associated with seven climate observation stations in the Dallas-Ft. Worth …

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Using Avhrr Data For Quantitative Estimation Of Vegetation Conditions: Calibration And Validation, Anatoly A. Gitelson, Felix Kogan, E. Zakarin, L. Spivak, L. Lebed Jan 1998

Using Avhrr Data For Quantitative Estimation Of Vegetation Conditions: Calibration And Validation, Anatoly A. Gitelson, Felix Kogan, E. Zakarin, L. Spivak, L. Lebed

School of Natural Resources: Faculty Publications

NDVI-derived Vegetation Condition Index (VCI) was compared with vegetation density, biomass and reflectance measured in the fields. The VCI numerically estimates fluctuation of NDVI related to intra-annual weather change only and is a measure of weather impact on vegetation. Test fields were located in different climatic (annual precipitation 150-700 mm) and ecological zones (semi-desert to steppe-forest) with elevation from 200 to 700 m in Kazakhstan. A range of NDVI variation was from 0.05 to 0.47. The determination coefficient between AVHRR-derived vegetation state and actually measured vegetation density of more than 0.76 was achieved. For the first time it was shown …

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Windbreak Renovation, Craig Stange, Jon Wilson, James R. Brandle, Mike Kuhns Jan 1998

Windbreak Renovation, Craig Stange, Jon Wilson, James R. Brandle, Mike Kuhns

School of Natural Resources: Faculty Publications

Windbreaks are an integral part of many farms and ranches and provide critical protection for farmsteads, livestock and crops. Unfortunately, many windbreaks planted in the 1930s and 1940s are losing their effectiveness due to age, poor health or neglect. In some cases, the windbreak no longer has the necessary density to provide winter protection. In other cases, overcrowding may have reduced the health and vigor of the windbreak, or the windbreak may have been invaded by aggressive sod-forming grasses such as smooth brome, reducing tree growth. Whatever the reason, many older windbreaks need renovation.

All windbreaks, even well-designed ones, need …

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Survey Of Mollusks Of The Niobrara River: Final Report, Patricia W. Freeman, Keith Perkins Sep 1997

Survey Of Mollusks Of The Niobrara River: Final Report, Patricia W. Freeman, Keith Perkins

School of Natural Resources: Faculty Publications

We surveyed the mollusks of the Niobrara River in Nebraska from 1992–1996. We found two species of unionid clams and ten species of snails that either must live in water or near water. Both clams and snails are poorly sampled in the state, however we attribute the low number of species of unionid clams in the Niobrara to its cold, fast flow and rocky bottom. In contrast, the Platte River is slower moving with a muddy bottom and has at least 11 species of unionid clams. Each species has been mapped with latitude/longitude coordinates. Specimens have been curated and are …

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Coyote Food Habits At Desoto National Wildlife Refuge, Nebraska, Jeffrey J. Huebschman, Scott E. Hygnstrom, Joseph A. Gubanyi Jun 1997

Coyote Food Habits At Desoto National Wildlife Refuge, Nebraska, Jeffrey J. Huebschman, Scott E. Hygnstrom, Joseph A. Gubanyi

School of Natural Resources: Faculty Publications

Coyote (Canis latrans) food habits were detennined from 490 scats collected from October 1994 to October 1995 at DeSoto National Wildlife Refuge (DNWR), along the Nebraska/Iowa border. Mammals occurred most frequently, as measured by percent-of-scats (POS) , followed by vegetation, birds, and invertebrates. Mammals also constituted the largest portion of coyote diet, as determined by fresh weight correction factors. Within the mammalian category, white-tailed deer (Odocoileus virginianus) occurred most frequently and constituted the largest portion of diet by fresh weight correction factors. White-tailed deer occurrence and importance in diet peaked in June, which corresponds to the …

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Impacts Of Air Temperature Variations On The Boro Rice Phenology In Bangladesh: Implications For Irrigation Requirements, Rezaul Mahmood Apr 1997

Impacts Of Air Temperature Variations On The Boro Rice Phenology In Bangladesh: Implications For Irrigation Requirements, Rezaul Mahmood

School of Natural Resources: Faculty Publications

Air temperature significantly affects crop phenology. Numerous experiments have shown that prevailing air temperature determines the length of crop growth stages. Irrigation field requirements depend on the length of the crop growth stages. In the present study, a physically based parametric model, YIELD, has been applied to estimate the impacts of fluctuating air temperature (due to inter-annual climatic variability and global warming) on evapotranspiration water requirements and the length of growth stages of the irrigated boro rice in Bangladesh. The YIELD model is crop specific and crop-growth-stage specific which is a compromise between area-specific regression models and complex crop growth …

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Spectral Information Content Of The Boreal Forest, Elizabeth A. Walter-Shea Jan 1997

Spectral Information Content Of The Boreal Forest, Elizabeth A. Walter-Shea

School of Natural Resources: Faculty Publications

No abstract provided.

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Internal Anatomy Of The Snout And Paranasal Sinuses Of Hyaenodon (Mammalia, Creodonta), R. M. Joeckel, H.W. Bond, G.W. Kabalka Jan 1997

Internal Anatomy Of The Snout And Paranasal Sinuses Of Hyaenodon (Mammalia, Creodonta), R. M. Joeckel, H.W. Bond, G.W. Kabalka

School of Natural Resources: Faculty Publications

No abstract provided.

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Water-Balance Modeling In A Changing Environment: Reductions In Unconfined Aquifer Levels In The Area Between The Danube And Tisza Rivers In Hungary, Jozsef Szilagyi, Charles Vorosmarty Jan 1997

Water-Balance Modeling In A Changing Environment: Reductions In Unconfined Aquifer Levels In The Area Between The Danube And Tisza Rivers In Hungary, Jozsef Szilagyi, Charles Vorosmarty

School of Natural Resources: Faculty Publications

No abstract provided.

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Late Holocene Eolian Activity In The Mineralogically Mature Nebraska Sand Hills, Daniel R. Muhs, Thomas W. Stafford Jr., James B. Swinehart, Scott D. Cowherd, Shannon A. Mahan, Charles A. Bush, Richard F. Madole, Paula B. Maat Jan 1997

Late Holocene Eolian Activity In The Mineralogically Mature Nebraska Sand Hills, Daniel R. Muhs, Thomas W. Stafford Jr., James B. Swinehart, Scott D. Cowherd, Shannon A. Mahan, Charles A. Bush, Richard F. Madole, Paula B. Maat

School of Natural Resources: Faculty Publications

The age of sand dunes in the Nebraska Sand Hills has been controversial, with some investigators suggesting a full glacial age and others suggesting that they were last active in the late Holocene. New accelerator mass spectrometry radiocarbon ages of unaltered bison bones and organic rich sediments suggest that eolian sand deposition occurred at least twice in the past 3000 I4C yr B.P. in three widely separated localities and as many as three times in the past 800 14C yr at three other localities. These late Holocene episodes of eolian activity are probably the result of droughts more …

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Monitoring Of Polluted Water Bodies By Remote Sensing, Anatoly A. Gitelson, Robert Stark, Gideon Oron, Inka Dor Jan 1997

Monitoring Of Polluted Water Bodies By Remote Sensing, Anatoly A. Gitelson, Robert Stark, Gideon Oron, Inka Dor

School of Natural Resources: Faculty Publications

The purpose of this study is to evaluate a remote sensing method for real time monitoring of wastewater effluent. Reflectance in the range from 400 to 950 nm with a spectral resolution of 2 nm, simultaneously with turbidity, chlorophyll and total suspended matter contents were acquired in two wastewater systems: R "m and Naan, Israel. The reflectance spectra of wastewater effluent were investigated in order to develop algorithms for remote estimation of wastewater quality expressed as chlorophyll-α, bacteriochlorophyll-α, non-organic and total suspended matter concentrations. Reflectance height at 720 nm and an area above the base line from 670 to 950 …

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Ecological Water Treatment System For Removal Of Phosphorus And Nitrogen From Polluted Water, Ray W. Drenner, Donald J. Day, Stacy J. Basham, J. Durward Smith, Susan I. Jensen Jan 1997

Ecological Water Treatment System For Removal Of Phosphorus And Nitrogen From Polluted Water, Ray W. Drenner, Donald J. Day, Stacy J. Basham, J. Durward Smith, Susan I. Jensen

School of Natural Resources: Faculty Publications

We propose that phosphorus and nitrogen can be removed from polluted water using an ecological water treatment system consisting of periphyton and fish. In the proposed system, polluted water flows through a series of vessels, and the nutrients are taken up by periphyton growing on porous screens. Algal-grazing fish feed on the periphyton and either assimilate or egest the nutrients in mucus-bound feces that settle from the water into a sediment trap. Both the fish and their feces can be harvested as nutrient sinks. In this study we examined the effects of an algal-grazing cichlid (Tilapia mossambica) and …

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Sem Analysis Of Quartz Sand Grain Surface Textures Indicates Alluvial/Colluvial Origin Of The Quaternary "Glacial" Boulder Clays At Huangshan (Yellow Mountain), East-Central China, P. E. Helland, Pei-Hua Huang, Robert F. Diffendal Jr. Jan 1997

Sem Analysis Of Quartz Sand Grain Surface Textures Indicates Alluvial/Colluvial Origin Of The Quaternary "Glacial" Boulder Clays At Huangshan (Yellow Mountain), East-Central China, P. E. Helland, Pei-Hua Huang, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

Geomorphic features and Pleistocene deposits on Huangshan have been attributed to glaciation. Recent reassessment questions this interpretation. As part of the reassessment, quartz sand grains from deposits identified as glacial boulder clays (till composed of boulders in a clay or silt matrix) were analyzed by scanning electron microscope for evidence of their sedimentary history. Surface textures found on the boulder-clay grains were compared with those on grains with known sedimentary histories including glacial, grus, colluvial, and alluvial grains. The analysis shows that the grains lack typical glacial textures. The surface textures present indicate a complex history. Non-uniformly weathered grain surfaces …

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Prairie Legacies - Mammals, Russell A. Benedict, Patricia W. Freeman, Hugh H. Genoways Nov 1996

Prairie Legacies - Mammals, Russell A. Benedict, Patricia W. Freeman, Hugh H. Genoways

School of Natural Resources: Faculty Publications

Few North American ecosystems have been as dramatically altered by humans as the prairies of the Great Plains. Occupying the immense interior of North America, these deceiving grassland oceans hid their complexity and diversity from many early travelers who saw this area merely as an obstacle to overcome in their westward journeys. But for the careful observer, prairies hold a tremendous quantity of life, arranged in a diverse mosaic of patches ranging in scale from minute anthills to the vastness of the Nebraska Sandhills or Kansas Flint Hills. Not only is a given ridgetop subdivided into a number of areas …

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Reproductive Success Of Grasshopper Sparrows In Relation To Edge, Jennifer M. Delisle, Julie A. Savidge Sep 1996

Reproductive Success Of Grasshopper Sparrows In Relation To Edge, Jennifer M. Delisle, Julie A. Savidge

School of Natural Resources: Faculty Publications

Using an index based on observations of breeding behaviors, we estimated reproductive success of 31 territorial grasshopper sparrows (Ammodramus savannarum) on Conservation Reserve Program fields in southeast Nebraska. Reproductive success was 52%, and no difference was detected between birds holding interior (>100 m from the edge) vs. edge territories. However, grasshopper sparrows appeared to avoid nesting within 50 m of edge habitats. Territories ranged from 0.36-1.24 ha, and territory size did not differ between successful and unsuccessful males.

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Improving The Validation Of Model-Simulated Crop Yield Response To Climate Change: An Application To The Epic Model* Jour. Ser. No. 11339 Nebraska Ag. Res. Div., William E. Easterling, Xiafen Chen, Cynthia Hays, James R, Brandle, Hehui Zang Jun 1996

Improving The Validation Of Model-Simulated Crop Yield Response To Climate Change: An Application To The Epic Model* Jour. Ser. No. 11339 Nebraska Ag. Res. Div., William E. Easterling, Xiafen Chen, Cynthia Hays, James R, Brandle, Hehui Zang

School of Natural Resources: Faculty Publications

Crop models have been used extensively to simulate yield response to various scenarios of climate change. Such simulations have been inadequately validated, limiting their utility in policy analysis. In this research, it is argued that the performance of crop models during recent years of extreme weather conditions relative to current normals may give a better indication of the validity of model simulations of crop yields in response to climate change than performance during the full range of climate conditions (as is done now). Twenty years of the climate record (1971-1990) are separated into different growing season temperature and precipitation classes …

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Surface Exchange Of Water Vapour Between An Open Sphagnum Fen And The Atmosphere, S. B. Verma Jan 1996

Surface Exchange Of Water Vapour Between An Open Sphagnum Fen And The Atmosphere, S. B. Verma

School of Natural Resources: Faculty Publications

No abstract provided.

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Conifer Shoot Bidirectional Scattering: Methodology And Preliminary Results, E.A. Walter-Shea, M.A. Mesarch Jan 1996

Conifer Shoot Bidirectional Scattering: Methodology And Preliminary Results, E.A. Walter-Shea, M.A. Mesarch

School of Natural Resources: Faculty Publications

No abstract provided.

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The Local Effect Of Intermittency On The Inertial Subrange Energy Spectrum Of The Atmospheric Surface Layer, Jozsef Szilagyi, Gabriel G. Katul, Marc B. Parlange, John D. Albertson, Anthony T. Cahill Jan 1996

The Local Effect Of Intermittency On The Inertial Subrange Energy Spectrum Of The Atmospheric Surface Layer, Jozsef Szilagyi, Gabriel G. Katul, Marc B. Parlange, John D. Albertson, Anthony T. Cahill

School of Natural Resources: Faculty Publications

No abstract provided.

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The Influence Of Land Use/Land Cover On Climatological Values Of The Diurnal Temperature Range, Kevin P. Gallo, David R. Easterling, Thomas C. Peterson Jan 1996

The Influence Of Land Use/Land Cover On Climatological Values Of The Diurnal Temperature Range, Kevin P. Gallo, David R. Easterling, Thomas C. Peterson

School of Natural Resources: Faculty Publications

The diurnal temperature range (DTR) at weather observation stations that make up the U.S. Historical Climatology Network was evaluated with respect to the predominant land use/land cover associated with the stations within three radii intervals (100, 1000, and 10 000 m) of the stations. Those stations that were associated with predominantly rural land use/land cover (LULC) usually displayed the greatest observed DTR, whereas those associated with urban related land use or land cover displayed the least observed DTR. The results of this study suggest that significant differences in the climatological DTR were observed and could be attributed to the predominant …

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Estimation Of Seasonal Dynamics Of Pasture And Crop Productivity In Kazakhstan Using Noaa/Avhrr Data, Anatoly A. Gitelson, Felix Kogan, Lev Spivak, Edige Zakarin, Lubov Lebed Jan 1996

Estimation Of Seasonal Dynamics Of Pasture And Crop Productivity In Kazakhstan Using Noaa/Avhrr Data, Anatoly A. Gitelson, Felix Kogan, Lev Spivak, Edige Zakarin, Lubov Lebed

School of Natural Resources: Faculty Publications

Recently, NOAA developed the AVHRR-based Vegetation Condition Index (VCI) for drought monitoring. This index was used for estimating pasture and crop productivity in Kazakhstan. The results of VCI-derived vegetation conditions were compared with vegetation density, biomass and reflectance measured in different climatic and ecological zones with elevation from 200 to 700 m and a large range of the NDVI variation (over space and season) from 0.05 to 0.47. An estimation error of AVHRR-derived vegetation density was less than 16 per cent. First time it was shown that the VCI-derived vegetation condition data can be effectively used for quantitative assessments of …

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Novel Algorithms For Remote Sensing Of Chlorophyll Content In Higher Plant Leaves, Anatoly A. Gitelson, Mark N. Merzlyak, Yuri Grits Jan 1996

Novel Algorithms For Remote Sensing Of Chlorophyll Content In Higher Plant Leaves, Anatoly A. Gitelson, Mark N. Merzlyak, Yuri Grits

School of Natural Resources: Faculty Publications

The general features of reflectance spectra of higher plant leaves are considered with special reference to remote sensing of chlorophyll. Wavelengths with maximum sensitivity to chlorophyll content were found in the wide spectral range from 550 to 630 nm and near 700 nm. The wavelength of the red edge position of the reflectance spectrum correlated very closely with the reflectance at 550 and 700 nm. The ratios of reflectances in the near infra-red range of the spectrum (above 750 nm) to that at 700 nm RNIR/R700 and RNIR/R550 were directly proportional to the leaves' …

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Windbreak Management, Craig Stange Jan 1996

Windbreak Management, Craig Stange

School of Natural Resources: Faculty Publications

The windbreaks on your farm are an important part of the agricultural landscape. They provide protection for the farmstead, livestock, and crops; provide habitat for wildlife; and contribute to an overall healthy environment for you and your family. They are living systems with youth, maturity, and old age. Like any other living thing they need proper care and management in order to continue to function at their best.

Windbreak management requires an understanding of how your windbreak works. Your goal is to maintain the health and vigor of individual trees and shrubs while maintaining the overall structure of the windbreak …

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Windbreaks For Snow Management, James R. Brandle, H. Doak Nickerson Jan 1996

Windbreaks For Snow Management, James R. Brandle, H. Doak Nickerson

School of Natural Resources: Faculty Publications

In areas of high winds and blowing snow, windbreaks can reduce the amount of effort spent on snow management. They can be designed to spread snow across a large area or to confine it to a relatively small storage area. The design of your windbreak will depend on your objective. Field windbreaks designed to distribute snow evenly across a field should be tall and porous. In contrast, windbreaks designed to capture snow and control drifting should have multiple rows with high density. There is no one set design, number of rows, or width of planting that is ideal for every …

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Scale Issues In Soil Moisture Modelling: Problems And Prospects, Rezaul Mahmood Jan 1996

Scale Issues In Soil Moisture Modelling: Problems And Prospects, Rezaul Mahmood

School of Natural Resources: Faculty Publications

Soil moisture storage is an important component of the hydrological cycle and plays a key role in land-surface-atmosphere interaction. The soil-moisture storage equation in this study considers precipitation as an input and soil moisture as a residual term for runoff and evapotranspiration. A number of models have been developed to estimate soil moisture storage and the components of the soil-moisture storage equation. A detailed discussion of the implication of the scale of application of these models reports that it is not possible to extrapolate processes and their estimates from the small to the large scale. It is also noted that …

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Nectarivorous Feeding Mechanisms In Bats, Patricia W. Freeman Sep 1995

Nectarivorous Feeding Mechanisms In Bats, Patricia W. Freeman

School of Natural Resources: Faculty Publications

Cranio-dental characteristics are quantified between micro- and megachiropteran nectarivores and compared with microchiropteran animalivores, frugivores, and megachiropteran frugivores. Microchiropteran nectarivores share many characteristics with megachiropteran nectarivores and frugivores, but differ in having a long, narrow head. Megachiropterans have wide zygomata, which would allow for more jaw musculature. Diminutive cheekteeth are characteristic of nectarivory in both suborders, but both have relatively large canines. Teeth in nectarivores can occupy as little as a tenth of the palatal area compared to nearly two-thirds in microchiropteran animalivores. The proportion that the dilambdodont stylar shelf occupies of molars in microchiropteran nectarivores can be as much …

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Geology Of The Ogallala/High Plains Regional Aquifer System In Nebraska, Robert F. Diffendal Jr. Apr 1995

Geology Of The Ogallala/High Plains Regional Aquifer System In Nebraska, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

This guide is mostly figures with a reference section containing some of the pertinent literature on the Cenozoic geology we will see over the next four days. Copies of some of the cited works will be assembled in a packet and handed out on the morning of April 29th. We will make all 17 stops. if the weather is reasonably good and the roads are passable. On the first day, April 29, we will try to get to stops 1-5, the more distal parts of the Ogallala and younger deposits in Nebraska. On April 30, we will try to visit …

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Windbreak Shelter As A Function Of Wind Direction, James R. Brandle Jan 1995

Windbreak Shelter As A Function Of Wind Direction, James R. Brandle

School of Natural Resources: Faculty Publications

No abstract provided.

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