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Articles 18121 - 18150 of 19672

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Notes On Maternal Behavior And Post-Brooding Aggression In The Prairie Skink, Eumeces Septentrionalis, Louis A. Somma Jan 1985

Notes On Maternal Behavior And Post-Brooding Aggression In The Prairie Skink, Eumeces Septentrionalis, Louis A. Somma

Papers in Herpetology

Observations of three female prairie skinks (E. septentrionalis) obtained in Omaha, NE, in 1983, including nest building, oviposition, incubation, defensive behavior, grooming of hatchlings, neonatal care, and post-brooding aggression.


Predation In Insular Plant Dynamics: An Experimental Assessment Of Postdispersal Fruit And Seed Survival, Enewetak Atoll, Marshall Islands, Svata M. Louda, Paul H. Zedler Jan 1985

Predation In Insular Plant Dynamics: An Experimental Assessment Of Postdispersal Fruit And Seed Survival, Enewetak Atoll, Marshall Islands, Svata M. Louda, Paul H. Zedler

Svata M. Louda Publications

We studied predation upon the fruits of four common terrestrial plant species of atolls by excluding: 1) all predators; 2) large predators only; and 3) no predators. Each of these treatments was located within the vegetation at three distances from the shore: beach edge of fringing thicket; middle of the thicket; and inner forest. The plants were Terminalia catappa, Messerschmidia argentea, Scaevola taccada, and Guettarda speciosa. Predation loss over the year was significant (P < 0.01) for all four species. Location contributed significantly only for S. taccada. Amount of loss and predominant type of seed predator for a plant species were related to size and conspicuousness. The largest fruits, …


The Effects Of Prey Depletion On The Patch Choice Of Foraging Blue Jays (Cyanocitta Cristata), Alan Kamil, Sonja I. Yoerg Jan 1985

The Effects Of Prey Depletion On The Patch Choice Of Foraging Blue Jays (Cyanocitta Cristata), Alan Kamil, Sonja I. Yoerg

Papers in Behavior in Biological Sciences

Blue jays (Cyanocitta cristata) were trained to hunt for non-cryptic moths presented in projected images. On each trial, the jays chose one of two patches to hunt in: (1) a uniform, “non-depleting” patch with constant prey density of 0.25; or (2) a “depleting” patch in which prey density changed during the foraging bout. In the depleting patch, the initial prey density was 0.50, declining to zero in a single step part-way through each foraging bout (session). The patch choices of the jays were greatly affected by these conditions. The jays chose the depleting patch early in the session, …


Nearshore Foodwebs And The Distribution Of Acanthocephalan Parasites In Antarctic Seabirds, Eric P. Hoberg Jan 1985

Nearshore Foodwebs And The Distribution Of Acanthocephalan Parasites In Antarctic Seabirds, Eric P. Hoberg

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Field studies, in the vicinity of Palmer Station during the austral summer of 1982— 1983, yielded an extensive collection of acanthocephalans and other parasites from seabirds, fish and invertebrates. The continuing analysis of this material has resulted in the elucidation of factors that control the occurrence of Corynosoma spp. in Antarctic seabirds. Notably, the host-distribution of Corynosoma spp. suggested that these parasites were being acquired from piscine or possibly amphipod prey, generally in nearshore habitats.


Gametogenesis En Chthonerpeton Indistinctum (Gymnophiona: Typhlonectidae), Rafael O. De Sá, Nibia Berois Jan 1985

Gametogenesis En Chthonerpeton Indistinctum (Gymnophiona: Typhlonectidae), Rafael O. De Sá, Nibia Berois

Biology Faculty Publications

RESUMEN:

Histológicamente, las gónadas de Chthonerpeton indistinctum son similares a las ya descritas para otras especies del orden Gymnophiona. Los lóbulos testiculares se hallan compartimentados en unidades estructurales denominadas lóculos. La espermatogénesis ocurre en cistos sincrónicos de células germinales. Durante la espermiogénesis se identifican cuatro estados consecutivos de desarrollo: 1) cistos de espermátidas redondeadas; 2) cistos de espermátidas arrifionadas; 3) cistos de espermátidas bastoniformes y 4) espermátidas en ramillete.

El análisis histológico de los ovarios mostró la presencia de tres estados en la maduración de los folículos ováricos. Estas etapas pueden ser identificadas de acuerdo a: 1) ubicación del folículo …


Estructura Del Ovario De Chthonerpeton Indistinctum (Reinhardt Y Lutken, 1862) (Amphibia: Gymnophiona) Durante La Gestación, Rafael O. De Sá, Nibia Berois Jan 1985

Estructura Del Ovario De Chthonerpeton Indistinctum (Reinhardt Y Lutken, 1862) (Amphibia: Gymnophiona) Durante La Gestación, Rafael O. De Sá, Nibia Berois

Biology Faculty Publications

La morfología e histología del ovario para varias especies del orden Gymnophiona ha sido reportada por Wake (1968, J. Morphol. 126, 291) y para C. indistinctum por los autores (1984, XXIV Reunión de Comunicaciones, Soc. Zool. Uruguay).

Continuando con los estudios sobre el aparato genital de esta especie vivípara, se presenta ahora la estructura del ovario durante la gestación.

Se procesaron con fines histológicos, ovarios de dos hembras grávidas colectadas en las costas de los Dep. Montevideo y San José en abril, 1983. El número de ejemplares trabajados es muy reducido dado lo difícil que resulta su colecta …


The Prairie Naturalist Volume 16, No. 4. December 1984 Dec 1984

The Prairie Naturalist Volume 16, No. 4. December 1984

The Prairie Naturalist

Paul B. Kannowski, Editor

Nikki R. Seabloom, Assistant Editor

Douglas H. Johnson, Book Review Editor

TABLE OF CONTENTS

VEGETATION PATTERNS IN RELATION TO TOPOGRAPHY AND EDAPHIC VARIATIONS IN NEBRASKA SAND HILLS PRAIRIE ▪ P. W. Barnes, A. T. Harrison and S. P. Heinisch

GREAT BLUE HERON NESTING BIOLOGY ON THE JAMES RIVER IN SOUTH DAKOTA ▪ E. M. Dowd and L. D. Flake

OVENBIRDS AT THE PERIPHERY OF THEIR RANGE IN WESTERN NORTH DAKOTA ▪ R. B. Hopkins

BREEDING BIRD COMMUNITY COLONIZATION OF SOWN STANDS OF NATIVE GRASSES IN NORTH DAKOTA ▪ K. F. Higgins, T. W. Arnold and R. …


Benthic Diatom Community Dynamics In The Colorado River: Interactive Effects Of Periodic Dessication And Current Regime, Christopher Gerard Peterson Dec 1984

Benthic Diatom Community Dynamics In The Colorado River: Interactive Effects Of Periodic Dessication And Current Regime, Christopher Gerard Peterson

Publications (WR)

The response to periodic desiccation of periphyton communities developed in eddy environments or in areas exposed to variable, direct current was examined. Algal communities were incubated on clay tiles for between 2 and 12 weeks in the Colorado River, directly below Hoover Dam from October, 1983 - January, 1984. Mean daily discharge from the dam decreased over this period. To assess the influence of these discharge changes on community dynamics, samples collected over the first 12 weeks of the investigation were compared to samples of the same age collected over the final 8 weeks.

The small diatom taxon Achnahthes spp …


Vegetation Patterns In Relation To Topography And Edaphic Variation Nebraska Sandhills Prairie, P. W. Barnes, A. T. Harrison, S. P. Heinisch Dec 1984

Vegetation Patterns In Relation To Topography And Edaphic Variation Nebraska Sandhills Prairie, P. W. Barnes, A. T. Harrison, S. P. Heinisch

School of Biological Sciences: Faculty Publications

Detailed studies on soil texture and moisture retention indicate a close association between edaphic features and the distribution and composition of plant communities along topographic gradients at Arapaho Prairie, a typical, semi-arid Nebraska Sandhills prairie. The vegetation characteristics of three major habitat types (ridge, slope, and valley) and several minor subtypes (swale, stable ridge, and eroding ridge) are recognized and quantitatively described. Texture analysis indicates that the soils of dune slopes and ridges are largely azonal and are very coarse with substantially lower fine fractions (silt-clay ~ 13-15%) than soils of the more lowland swale and valley sites where surfact …


A Proposal To Fertilize The Overton Arm And Gregg Basin Areas Of Lake Mead, Larry J. Paulson Nov 1984

A Proposal To Fertilize The Overton Arm And Gregg Basin Areas Of Lake Mead, Larry J. Paulson

Publications (WR)

Several limnological studies have been conducted in Lake Mead during the past decade. The recent studies clearly show that most of Lake Mead is deficient in nutrients, especially phosphorus, and very low in productivity. The reservoir-wide average total phosphorus concentration for 1981 - 1982 was only 9 mg/m3. This is below levels found In most oligotrophic lakes and reservoirs. Algal biomass, as measured by chlorophyll-a, averaged only 1.5 mg/m3. That also places Lake Mead in the oligotrophic range. Transparency, as measured by a Secchi disc, averaged 9-5 m in Lake Mead during 1981-1982. That far exceeds …


Life History Patterns And The Comparative Social Ecology Of Carnivores, Marc Bekoff, Thomas J. Daniels, John L. Gittleman Nov 1984

Life History Patterns And The Comparative Social Ecology Of Carnivores, Marc Bekoff, Thomas J. Daniels, John L. Gittleman

Ethology Collection

No abstract provided.


Demographic Analysis And Microhabitat Relationships Of A Small Mammal Community In Clearings Of The Great Dismal Swamp, Jean Ferguson Stankavich Oct 1984

Demographic Analysis And Microhabitat Relationships Of A Small Mammal Community In Clearings Of The Great Dismal Swamp, Jean Ferguson Stankavich

Biological Sciences Theses & Dissertations

Small mammals were trapped for 14 months on two grids located within a powerline right-of-way in the Great Dismal Swamp National Wildlife Refuge. During 12,354 trap nights, individuals of 10 different species were captured. They included, from highest to lowest density, Reithrodontomys humulis, Ochrotomys nuttalli, Peromyscus leucopus, Blarina brevicauda, Synaptomys cooperi, Microtus pennsylvanicus, Microtus pinetorum, Sigmodon hispidus, Mus musculus and Oryzomys palustris. The demography (densities, reproduction, home range and dispersal) of each species was analyzed when possible. Most of the species were present in relatively low densities, with a number being captured only during the latter months of the study. …


Catalog Of The Recent Scandentia And Primates In The Carnegie Museum Of Natural History, Suzanne B. Mclaren, Duane A. Schlitter, Hugh H. Genoways Sep 1984

Catalog Of The Recent Scandentia And Primates In The Carnegie Museum Of Natural History, Suzanne B. Mclaren, Duane A. Schlitter, Hugh H. Genoways

University of Nebraska State Museum: Mammalogy Papers

The Section of Mammals, Carnegie Museum of Natural History, houses six specimens of Recent tree shrews and 611 specimens of Recent primates. The only family in the Order Scandentia is Tupaiidae. Primate families represented are Lemuridae, Lorisidae, Cebidae, Callitrichidae, Cercopithecidae, Pongidae, and Hominidae. For each specimen the following data are recorded: locality; date collected; catalog number; sex; age; nature of specimen; condition of specimen and comments. The latter category gives information on the condition of the skin and skeletal material, and gives information on the availability of the specimen.


The Prairie Naturalist Volume 16, No. 3. September 1984 Sep 1984

The Prairie Naturalist Volume 16, No. 3. September 1984

The Prairie Naturalist

Paul B. Kannowski, Editor

Nikki R. Seabloom, Assistant Editor

Douglas H. Johnson, Book Review Editor

TABLE OF CONTENTS

GRASSLAND HABITAT MANAGEMENT USING PRESCRIBED BURNING IN WIND CAVE NATIONAL PARK, SOUTH DAKOTA ▪ J. D. Forde, N. F. Sloan and D. A. Shown

BODY TEMPERATURES AND BEHAVIORAL ACTIVITIES OF HIBERNATING

PRAIRIE RATTLESNAKES, Crotalus viridis, IN ARTIFICIAL DENS ▪ K. R. Marion and O. J. Sexton

NEW VASCULAR PLANT RECORDS FOR NORTH DAKOTA ▪ D. T. Disrud, W. T. Barker and R. H. Warner

CHRISTMAS BIRD COUNTS FOR NORTH DAKOTA - 1983 ▪ R. N. Randall

COMPARISON OF PLANKTON POPULATIONS IN THREE …


An Evaluation Of Naturally Occurring Populations Of Magnolia Tripetala L. In Indiana, Kemuel S. Badger Aug 1984

An Evaluation Of Naturally Occurring Populations Of Magnolia Tripetala L. In Indiana, Kemuel S. Badger

All-Inclusive List of Electronic Theses and Dissertations

Magnolia tripetala L. occurs in Indiana as a disjunct from the Appalachian mountains populations. Currently, the known distribution of ~· tripetala in Indiana is confined to seven sites in Crawford County. The current status of ~· tripetala and the surrounding plant community was evaluated to aid in the future study, protection and management of this species, which is endangered in Indiana. Systematic random sampling of the tree stratum was done with belt transects. The sapling and seeding strata were sampled with subplots, placed along the belt transects. Permanent plots were established to enable future monitoring of what is currently prime …


An Ecological Investigation Of Native Grassland In Southern Lower Michigan, Kim Alan Chapman Aug 1984

An Ecological Investigation Of Native Grassland In Southern Lower Michigan, Kim Alan Chapman

Masters Theses

Floristic and soil data from 50 relicts and other sources were analyzed using polar ordination of species presence. Historical and early scientific accounts were interpreted from the results.

The relicts ranged from wet to dry, on either sandy or loamy soil. Alkaline lakeplain sites added a third dimension of variability. Most upland remnants were interpreted as fragments of former savanna.

Floristic composition and distribution of the remnants were determined by these factors:

1. Edaphic: away from the Prairie Peninsula, only very dry or very wet sites support prairie vegetation;

2. Phytogeographic: the farther from the Prairie Peninsula, the fewer characteristics …


Results Of The Alcoa Foundation-Suriname Expeditions. Ix. Bats Of The Genus Tonatia (Mammalia: Chiroptera) In Suriname, Hugh H. Genoways, Stephen L. Williams Jul 1984

Results Of The Alcoa Foundation-Suriname Expeditions. Ix. Bats Of The Genus Tonatia (Mammalia: Chiroptera) In Suriname, Hugh H. Genoways, Stephen L. Williams

University of Nebraska State Museum: Mammalogy Papers

Five species of Tonatia (bidens, brasilense, carrikeri, schulzi, and silvicola) are known to occur in Suriname. Tonatia bidens and silvicola are the largest in overall size (forearm length over 50 mm and greatest length of skull over 27.0 mm). However, T. bidens has a broader postorbital region (5.0 mm or more) and narrower mastoid region (less than 13.0 mm). The lower incisors of T. bidens are also noticeably broader than those of T. silvicola. These two species were found throughout most of the forested areas of Suriname. T. bidens displayed no secondary sexual …


Life History Aspects Of Reithrodontomys Humulis In Southeastern Virginia, Michelle Cawthorn Chandler Jul 1984

Life History Aspects Of Reithrodontomys Humulis In Southeastern Virginia, Michelle Cawthorn Chandler

Biological Sciences Theses & Dissertations

Reithrodontomys humulis, the eastern harvest mouse, is a small cricetid rodent which is common in old field communities in the eastern U.S. A live-trapping study was conducted in Suffolk, Virginia from March 1983 through February 1984 in order to learn the details of its life history and the vegetational characteristics which best describe its microhabitat. Specifically, population densities, trap-revealed survival times, home ranges, plant species composition of the study area, and vegetational structure were examined. In order to trap as many Reithrodontomys as possible, special traps which excluded animals weighing over 20 g were constructed. Densities of harvest mice …


Determinants Of Variation In Avian Mobbing Behavior, Charles Ray Chandler Jr. Jul 1984

Determinants Of Variation In Avian Mobbing Behavior, Charles Ray Chandler Jr.

Biological Sciences Theses & Dissertations

Using three combinations of two experimental stimuli, I initiated mobbing behavior in various species of birds. The objectives of this research were to test the effects of stimuli on mobbing, the predictions of the hypothesis that mobbing functions to drive a predator away, and the effect of other species and individuals on the mobbing behavior of a bird. Mobbing experiments were conducted in a variety of habitats and locations from January 1983 through February 1984.

Only 6.5% of all trials with the mount-only stimulus were successful in attracting birds. Tape-only and mount-and-tape stimuli were equally effective in attracting birds, but …


The Role Of Colonization Predation And Season In Determining Macroinvertebrate Community Structure In A Temperate Lake, Cheryl Lynn Frew Jul 1984

The Role Of Colonization Predation And Season In Determining Macroinvertebrate Community Structure In A Temperate Lake, Cheryl Lynn Frew

Biological Sciences Theses & Dissertations

Field experiments were conducted to examine the effects of distance from shore, vertebrate predation, and season on macroinvertebrate colonization dynamics in a temperate lake in Suffolk, VA. In a year-long colonization study, artificial plants, half of which were caged to exclude vertebrate predators, were deployed in patches at three distances from shore (2m, 15m, 50m). Artificial plant subsamples were removed at weekly intervals over 28 days during four seasons to monitor colonization by macroinvertebrates. Colonization of artificial plants occurred more quickly in the summer and spring than in fall and winter. The interactive effect of distance from shore and cage …


Activity Levels Of Arboreal Rodents Peromysus And Ochrotomys Evaluated With Nest Cans In Seasonally Flooded Forests, John W. Walke Jul 1984

Activity Levels Of Arboreal Rodents Peromysus And Ochrotomys Evaluated With Nest Cans In Seasonally Flooded Forests, John W. Walke

Biological Sciences Theses & Dissertations

The diversity and density of small mammals in the Dismal Swamp are believed to be small. To test this, four 1.96 ha grids were established and operated in the Dismal Swamp National Wildlife Refuge, from September 1981 to November 1982. Number 10 metal cans covered with plastic lids were placed as nest boxes at 0.5 to 1.5 m height on trees. A 2.5 cm hole allowed access by arboreal rodents, to each nest can. The activity level of the two arboreal rodents, Peromyscus leucopus and Ochrotomys nuttalli, was evaluated by observing types of activity ranging from presence of mice to …


The Prairie Naturalist Volume 16, No. 2. June 1984 Jun 1984

The Prairie Naturalist Volume 16, No. 2. June 1984

The Prairie Naturalist

Paul B. Kannowski, Editor

Nikki R. Sea bloom , Assistant Editor

Douglas H. Johnson, Book Review Editor

TABLE OF CONTENTS

AUTUMN WEIGHTS OF PLAINS SHARP-TAILED GROUSE IN MONTANA ▪ J. E. Swenson and R. L. Eng

VEGETATION PROFILE AND GRASSLAND BIRD RESPONSE TO SPRING BURNING ▪ G. E. Huber and A. A. Steuter

WETLAND PRESERVATION CONFLICTS IN NORTH DAKOTA: ECONOMIC INCENTIVES AND LANDOWNER ATTITUDES ▪ R. D. Saylor, R. A. Stromstad and M. E. Winger

COLLEMBOLA OF SOUTHWESTERN NORTH DAKOTA: SPECIES COMPOSITION AND HABITAT DISTRIBUTION ▪ B. L. Benner and P. B. Kannowski

NEW RECORDS OF EARTHWORMS FROM KANSAS (Oligochaeta: …


The Hellbender, Cryptobranchus Alleganiensis, In Indiana, William H. Kern Jr. May 1984

The Hellbender, Cryptobranchus Alleganiensis, In Indiana, William H. Kern Jr.

All-Inclusive List of Electronic Theses and Dissertations

Very 1 ittle was previously known ubout the Hellbender, Crrp:t:£branchus alleganiensis alleganiensis, in Indiana. The purpose of this study was to determine its current range and status in Indiana and collect life history information. The hell benders were captured by hand from under rocks and 1d th hoopnets baited with cut fish. They were tagged, measured, wei~hed, examined for large external parasites, wounds, and reproductive cond:i - tion. Stoma ch contents were taken with a non-lethal, stomach-flushfog technique. The animals were then released at the site of capture. Al though they were originally found in the Ohio River, \\'hi tewater …


Seasonal And Spatial Heterogeneity In The Limnetic Zooplankton Community Of Lake Mead, Gene Robert Wilde May 1984

Seasonal And Spatial Heterogeneity In The Limnetic Zooplankton Community Of Lake Mead, Gene Robert Wilde

Publications (WR)

Zooplankton samples collected from throughout Lake Mead, in 1981-1982, demonstrate the presence of a statistically significant seasonal and spatial heterogeneity in zooplankton densities. Seasonally, the major zooplankton groups were most abundant in the spring and fall, coincident with maxima in chlorophyll-a concentrations. Successions among the various rotifers, cladocerans and copepods present in the reservoir were influenced by food availability, diapause, predation by planktivorous fish and, possibly, water temperatures. Spatial heterogeneity in zooplankton densities was unrelated to water temperature, pH, conductivity and dissolved oxygen concentrations, but was related to the abundance of phytoplankton (chlorophyll-a concentrations) and fish. Statistical analyses indicate that …


The Role Of Nannoplankton In The Phytoplankton Dynamics Of Four Colorado River Reservoirs (Lakes Powell, Mead, Mohave, And Havasu), Jeffrey John Janik May 1984

The Role Of Nannoplankton In The Phytoplankton Dynamics Of Four Colorado River Reservoirs (Lakes Powell, Mead, Mohave, And Havasu), Jeffrey John Janik

Publications (WR)

Phytoplankton species composition and community size structure were studied in four warm-monomictic Colorado River reservoirs; lakes Powell, Mead, Mohave, and Havasu from March 1981 to February 1982. Sampling was done at approximately monthly intervals from several stations in each reservoir. The Utermohl technique was used to enumerate phytoplankton. The phytoplankton assemblage was divided into the following six size classes using microscopic techniques; netplankton (>64 um), and nannoplankton (>5, 5-11, 12-21, 22-44, and 45-64 um).

Total phytoplankton biomass and community size structure were different among these four reservoirs with considerable spatial and temporal variation present. Average reservoir-wide areal weighted …


Initial Assessment Of The Introduction Of Spottail Shiner (Notropis Hudsonius) And Delta Smelt (Hypomesus Transpacificus) Into Willard Bay Reservoir, Utah., Thomas E. Sommerfeldt May 1984

Initial Assessment Of The Introduction Of Spottail Shiner (Notropis Hudsonius) And Delta Smelt (Hypomesus Transpacificus) Into Willard Bay Reservoir, Utah., Thomas E. Sommerfeldt

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Spottail shiner (Notropis hudsonius) and delta smelt (Hypomesus transpacificus) were introduced into Willard Reservoir to improve the forage base for walleye (Stizostedion vitreum vitreum) and black crappie (Pomoxis nigromaculatus). Spottail shiners were stocked in early spring in 1981, 1982, and 1983. Hauling mortality was generally great and an estimated 34,500 live fish were stocked in the 3-year period. Spottail shiner reproduction occurred each year of stocking. Delta smelt were introduced in 1982 with the stocking of 15,000 adult spawning fish. Stocking survival was estimated at 99%. Freshly spawned eggs were also obtained …


Seed Reserves In Stockpiled Topsoil On A Coal Mine Near Kemmerer, Wyoming, Cynthia K. Johnson May 1984

Seed Reserves In Stockpiled Topsoil On A Coal Mine Near Kemmerer, Wyoming, Cynthia K. Johnson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The objectives of this study were to determine how seed reserves varied with depth in topsoil stockpiles and to evaluate the effect of length of time of storage on the number of viable seeds and number of species of seeds.

Soil samples were taken from five topsoil piles representing zero to three years of storage on the Elkol-Sorenson mine near Kemmerer in southwestern Wyoming. Seeds were extracted using flotation/separation methods and were tested for viability using 2,3,5-triphenyl tetrazolium chloride solution. Data were analyzed using nonparametric statistical tests.

Overall density of seeds in topsoil piles was low. No relationship was found …


Effects Of Clearcutting On Forage Production, Quality And Decomposition In The Caatinga Woodland Of Northeast Brazil: Implications To Goat And Sheep Nutrition, Robert D. Kirmse May 1984

Effects Of Clearcutting On Forage Production, Quality And Decomposition In The Caatinga Woodland Of Northeast Brazil: Implications To Goat And Sheep Nutrition, Robert D. Kirmse

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Clearing of trees from the so-called caatinga woodland that characterizes the vegetation of the semi-arid region of northeast Brazil offers possibilities for increasing forage production. This research analyzed the first-year effects of clearing caatinga on dry season forage for goats and sheep. In addition, factors affecting litter decomposition on cleared and uncleared caatinga were assessed to evaluate the viability of deferring grazing of forages during the wet season for use later in the dry season.

Removing the trees resulted in a sixfold increase in production of herbaceous vegetation, however, 88 percent of the increased yield on the cleared areas was …


Plant Gas Exchange Of Two Bunchgrasses In Relation To Herbivory Tolerance, Robert S. Nowak May 1984

Plant Gas Exchange Of Two Bunchgrasses In Relation To Herbivory Tolerance, Robert S. Nowak

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The occurrence of compensatory photosynthesis was examined in the field during the spring for all foliage elements on two Agropyron bunchgrass species that differ in their evolutionary history of grazing pressure. Compensatory photosynthesis did occur in many individual foliage elements during at least part of their ontogeny. For both species, compensatory photosynthesis was related primarily to delayed leaf senescence and increased soluble protein concentrations, but not to an improvement in the water status of clipped plants. Photosynthetic water use efficiency and photosynthetic rates per unit soluble protein of foliage on partially defoliated plants were not increased following the clipping treatments. …


Social Play Behavior, Marc Bekoff Apr 1984

Social Play Behavior, Marc Bekoff

Ethology Collection

Recent studies clearly indicate that animal play is an important behavioral phenotype, and that detailed analyses of the phenomenon are useful for furthering our understanding of the evolution of social behavior and the interaction of phylogeny, ecology, and behavioral development. This article is concerned mainly with evolutionary, ecological, and developmental aspects of social play behavior in mammals.