Physical Sciences and Mathematics Commons^™

Form, Function, And Evolution In Skulls And Teeth Of Bats, Patricia W. Freeman

School of Natural Resources: Faculty Publications

Bats provide a model system for tracking change from the primitive mammalian tooth pattern to patterns indicating the more-derived food habits of carnivory, nectarivory, frugivory, and sanguinivory. Whereas microchiropteran bats show all these transitions, megachiropterans illustrate an alternative pattern concerned only with frugivory and nectarivory. In microchiropterans, it is likely that carnivory nectarivory, frugivory, and sanguinivory are all derived from a dilambdodont insectivorous tooth pattern. Megachiropterans are troublesome because they appear as nectarivores or frugivores without a clear relationship to ancestral taxa.

The nature of the food item and how teeth respond to that item evolutionarily is an issue I …

Amphibians And Reptiles [Of The Sand Hills], Patricia W. Freeman

School of Natural Resources: Faculty Publications

Of the 60 species of amphibians and reptiles presently known from Nebraska, 27 are found in the Sand Hills and one more is marginal to the east. Fourteen species of the 60 are essentially state wide in distribution, including the Sand Hills, and eight species of reptiles are strongly influenced by the Sand Hills (Lynch, 1985). Of 12 species that occur widely over the moister eastern part of the state, only four extend into the Sand Hills, and one occurs only under the wet conditions along the rivers of the eastern Sand Hills.

Amphibians: Tiger salamander (Ambystoma tigrinum); …

Mammals [Of The Sand Hills], Patricia W. Freeman

School of Natural Resources: Faculty Publications

Of approximately 81 species of mammals present in Nebraska today, 55 occur in the Sand Hills, with an additional three species that are associated only with the Niobrara River. Nebraska as a whole is truly a crossroads for mammals because two-thirds of the species reach their distributional limits in the state (Jones, 1964). Most of these mammals are widespread species or are specific to the grasslands as a whole and are not affected by this sandy zone. Jones (1964) wrote that “only a few mammals are restricted to this area. Mostly it serves to filter western species moving east and, …

Relationship Between Ecosystem Productivity And Photosynthetically Active Radiation For Northern Peatlands, S. E. Frolkin, J.L. Bubier, T.R. Moore, T. Ball, L.M. Bellisario, A. Bhardwaj, P. Carroll, P.M. Crill, Peter M. Lafleur, J.H. Mccaughey, N.T. Roulet, A. E. Suyker, S.B. Verma, J.M. Waddington, G.J. Whiting

School of Natural Resources: Faculty Publications

We analyzed the relationship between new ecosystem exchange of carbon dioxide (NEE) and irradiance (as photosynthetic photon flux density of PPFD), using published and unpublished data that have been collected during midgrowing season for carbon balance studies at seven peatlands in North America and Europe. NEE measurements included both eddy-correlation tower and clear, static chamber methods, which gave very similar results. Data were analyzed by site, as aggregated data set for all peatland type (bog, poor fen, rich fen, and all fens) and as a single aggregated data set for all peatlands. In all cases, a fit with a rectangular …

Air Temperature Variations And Rice Productivity In Bangladesh: A Comparative Study Of The Performance Of The Yield And The Ceres-Rice Models, Rezaul Mahmood

School of Natural Resources: Faculty Publications

Potential increase in air temperature due to climatic change and inter-annual climatic variability and its impacts on crop productivity is of major concern to crop scientists. A number of physically-based models have been developed and applied to estimate crop–environment relationships. In the present study the performance of two such models (the YIELD and the CERES-Rice) are discussed. These two models are used to estimate boro rice productivity under normal and abnormal climate scenarios in Bangladesh. This study finds that boro rice productivity at Mymensingh predicted by the YIELD is higher than the prediction by the CERES-Rice. Productivity estimates for Barisal …

Climatology Of The Daily Temperature Range Annual Cycle In The United States, Daniel J. Leathers, Michael A. Palecki, David A. Robinson, Kenneth F. Dewey

School of Natural Resources: Faculty Publications

Many researchers are presently interested in detecting long-term trends in annual or seasonal daily temperature range (DTR), and attributing these changes to anthropogenic origins. However, very little work has been done to confirm the mechanisms that are important to determining the long-term average annual cycle of the DTR. Therefore, the focus of this work is to examine the spatial and temporal difference in the DTR average annual cycle across the United States, and to associate the patterns of these cycles with potential causal variables. Three major types of DTR annual cycle exist in the United States: high sun season maximum …

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.

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.

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 …

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 …

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 …