bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen Consumption, Ambient Temperature and Excretion of Phosphorus‐32 in Cotton Rats
Authors: Wagner C. Kenyon
Published: May 2006

One of the major difficulties in evaluating energy flow in natural animal populations is the determination of field metabolism. Various writers have suggested that there may be a correlation between excretion rate of a radioactive isotope and metabolism in small mammals which might be used to determine metabolism in free—ranging animals. To test this hypothesis, cotton rats confined in the laboratory and in field enclosures were injected with P32 and their excretion rates were measured. Oxygen consumption also was measured in the laboratory animals. A poor correlation was found between oxygen consumption and excretion rate in the laboratory while a significant correlation was found between P32 excretion rate, oxygen consumption and temperature. Assuming that this correlation held true in the field, oxygen consumption was predicted in the field population, as 2.37 cc O2/g hr—1 in July, 3.41 cc O2/g hr2o1 in September and 4.02 cc O2/g hr—1 in November. Oxygen consumption in the field was not significantly higher than in the laboratory, indicating that the cotton rats did not expend a significantly greater amount of energy in the field. The use of the excretion rate of a radioactive element as a predictor of metabolism was criticized due to the high variance and lack of correlation between excretion rate and metabolism at the individual level.
Metronome Timing in Behavioral Ecology Studies
Authors: Wiens John A. , Martin Stephen G. , Holthaus Walter R. , Iwen Frank A.
Published: May 2006

An inexpensive, portable, electronic metronome emits tone pulses through an earphone at intervals which can be varied from 1 to 20 sec, and may be used in a variety of ways to provide a time base for studies in behavioral ecology. Several suggestions for the conduct of field studies in behavioral ecology are made.
Mortality of Transplanted Saguaro Seedlings
Authors: Turner Raymond M. , Alcorn Stanley M. , Olin George
Published: May 2006

Only 26 of an original 800 5—cm—tall saguaros (Carnegiea gigantea) survived for 3 months when accessible to the rodents and rabbits at Saguaro National Monument, Arizona; after 1 year all of these small plants were gone. Although losses among a group of larger (15—cm—tall) seedlings were less abrupt, only one plant of an original 120 remained by the end of a year. When protected from these herbivores by cages, 12% of the smaller plants remained at the end of 1 year but only 2% after 5 years. Although browsing by rodents and lagomorphs quickly destroyed most uncaged small plants, the planting design probably accentuated the losses from the herbivores; in any event, many of these seedlings would soon have died from other causes.
Pollen Analysis of Iola Bog and Paleoecology of the Two Creeks Forest Bed, Wisconsin
Authors: Schweger Charles Earl
Published: May 2006

Pollen analysis of Duck Creek Ridge, eastern Outagamie County, and Peter's Quarry, northeastern Brown County, two exposures of the Two Creeks Forest bed was completed to gain a more through understanding of the Two Creeks vegetation. Pollen and macrobotanical data reveal a simple flora dominated by boreal wetland pioneers Picea and Larix along with Cyperacea. Because of the high amounts of non—arboreal pollen, the general lack of stumps, roots, and logs associated with the deposit, and the field relations, the Two Creeks vegetation is believed to have been an open boreal woodland. Iola Bog, near the town of Iola in western Waupaca County, provided a late—glacial pollen record from outside the region of the Valders advance. The pollen record from Iola Bog was divided into nine zones that correlate well with the known glacial and climatic fluctuations, as well as with other work done in central Wisconsin. A basal Picea—Cyperaceae assemblage is replaced by a species—rich, mesic vegetation that represents the Two Creeks, interval. A drying trend is inferred to correlate with the Valders readvance; zones above this record the postglacial Pinus invasion and an Hypsithermal. A comparison of the Two Creeks localities and the Two Creeks core interval reveal marked differences in the inferred vegetation. This difference is explained by the shorter period the Two Creeks sites were exposed for revegetation and the pattern of invasion and colonization by boreal pioneer species.
Effects of Litter of Artemisia, Chrysothamnus, and Tortula on Germination and Growth of Three Perennial Grasses
Authors: Schlatterer Edward F. , Tisdale E. W.
Published: May 2006

Litter of Tortula ruralis, Artemisia tridentata, and Chrysothamnus viscidiflorus retarded germination and early growth of Stipa thurberiana, Sitanion hystrix, and Agropyron spicatum grow in a soil medium under greenhouse conditions. Four weeks after germination, growth was stimulated by the presence of these litter materials. Stimulation was attributed to a greater availability of nitrogen in the Tortula and Artemisia litter, but in the case of Chrysothamnus there is some evidence for the occurrence of an additional growth—promoting substance.
Tests of Solar Radiation Models in Three Forest Canopies
Authors: Miller Philip C.
Published: May 2006

Several models expressing the decrease of solar radiation in vegetation canopies have been proposed. The models are similar in (1) including a method of projecting the shadow of one more leaves onto a horizontal plane and (2) including a method of relating the projected shadow to the decrease of solar radiation. The models differ in the equations used and in the assumptions made. The models used the binomial, the Poisson, or some modification of the binomial to relate the projected shadow to the radiation at different levels. When the models were tested against the percentage of sunlit area at different levels in the canopy, the best fitting models was one proposed in this paper in which the shadow of the leaf is projected as a shadow of a cone and the binomial is used to express the decrease of radiation. Negative exponential models usually overestimated the percentage of sun. Including the shadow cast by twigs and branches in the prediction improved the agreement between the observed and the expected percentage of sun. Primary production models in which the negative exponential is used to calculate solar radiation may overestimate the actual production.
Starling Dispersal From a Winter Roost
Authors: Hamilton William J. , Gilbert William M.
Published: May 2006

Starling roosting behavior is considered in terms of resource acquisition. Our hypothesis is that dispersing starlings behave to maximize the efficiency and rate of energy gain. This hypothesis can explain of the winter starling roosting behavior. The value of strategies pursued by individuals within the system depends upon the size of the population utilizing a roost. As the roost population grows, more distant resources are utilized. At maximum roost populations individuals may disperse daily as much as 50 miles from the roost. During dispersal most individuals make in—transit stops to feed. These stops may provide information about the potentially more lucrative energy reserves nearer the roost, reducing the distance flown when they are favorable. Flocking actions probably make resource evaluation more efficient because the experience of the members of a group will provide more reliable information about the values of a resource field than an individual's personal experience. Linear dispersal directly away from roots is assumed to be maximally advantageous. This is because intraspecific competition declines with distance from the roost, and flight is costly of energy. On foggy, and overcast mornings dispersing starlings do not extend as far from the roost, and the flight is less accurately oriented. This suggest a relatively high adaptive value for accurate orientation mechanisms in this socio—economic system. Dispersing flocks are larger during overcast, supporting the hypothesis that group processes in orientation enhance orientation accuracy.
An Hypothesis to Explain the Incidence of Monophagy
Authors: Levins Richard , MacArthur Robert
Published: May 2006

An insect's choice of food plant is assumed to be based on a simple decision rule that maximizes the expected production of offspring. Monphagy or polyphagy may be favored, depending on the proportion of an extended diet that would be unsuitable if chosen, versus the difficulty in finding the most suitable food.
Intraclonal Root Connections Among Quaking Aspen Trees
Authors: Tew Ronald K. , DeByle Norbert V. , Schultz John D.
Published: May 2006

Three tracer solutions applied to 46 aspen (Populus tremuloides) clones in northern Utah revealed as many as 43 stems connected on a common root system. The maximum lateral distance between a donor and a receptor tree was 16.9 m. The number of stems connected by roots was not related to the percentage of sand, gravel, or clay in the soil, or to bulk soil density or elevation of site.
Relationships between Some Nutritional Factors and the Distributions of Eucalyptus Gummifera and Eucalyptus Maculata
Authors: McColl J. G. , Humphreys F. R.
Published: May 2006

The sharply delimited distributions of Eucalpytus gummifera and Eucalyptus maculata on the south coast of New South Wales were not statistically correlated with differences in physical and chemical properties of the supporting soils. Slight trends suggest that E. gummifera soils are not different physical quality and of lower nutrient status than E. maculata soils. Pot trials of interspecific competition for soil nutrients were inconclusive. Long—term field trials are recommended in which interspecific competition for other factors is also encountered. Chemical analyses and a pot trial indicated low concentrations of nitrogen, phosphorus, and calcium in some soils of the study area. Pot trails suggest that E. gummifera seedlings require less soil nitrogen and calcium than do E. maculata seedlings. Correlations are significant at the 0.05 level between phosphorus and calcium concentrations in plant tissues and the corresponding concentrations in supporting in supporting soils. The two species appear to differ in their ability to take up, and perhaps their requirement for soil phosphorus, calcium, nitrogen, and possibly manganese.
The Calcium, Magnesium, Potassium, and Sodium Budgets for a Small Forested Ecosystem
Authors: Likens G. E. , Bormann F. H. , Johnson N. M. , Pierce R. S.
Published: May 2006

The balance of calcium, magnesium, potassium, and sodium was studied in six watersheds of the Hubbard Brook Experimental Forest at West Thornton, New Hampshire. These watersheds are characterized by a near climax, northern hardwoods ecosystem, humid continental climate, and acid metamorphic rock. Bedrock in the area is considered to be watertight. Weekly samples of precipitation and stream water were collected from June 1963 through May 1965. Cation analyses were made by atomic absorption spectrophotemetry. Precipitation was about 117 cm during 1963—64 and 95 cm during 1964—65 and did not differ significantly in amount with elevation. Loss of water by runoff from the system was about 68 cm during 1963—64 and 49 cm during 1964—65. Evapotranspirational losses were calculated at 49 cm in 1963—64 and 46 cm in 1964—65. About 37% of the total annual runoff ocurred in April and less than 0.2% in September. Concentration of Ca++, Mg++, K+, and Na+ in weekly precipitation samples was variable. The annual weighted average values (mg/liter) were : 1963—64, Ca 0.26, mg 0.06, K 0.21, Na 0.09; 1964—65, Ca 0.30, Mg 0.12, K 0.19, Na 0.22. Differences were not related to elevation. The contribution of cations from dry fallout was negligible. Cation content of stream water was relatively very low. The weighted average content for the entire area (mg/liter) was Ca 1018, Mg 0.38, K 0.26, Na 0.87 during 1963—64; and Ca 0.80, Mg 0.38, K 0.22, Na 0.91 during 1964—65. In general, the cationic concentrations in drainage water were constant although discharge or water varied greatly. Statistically, the relationship between concentration and discharge was not significant for Ca++ and Mg++ in any of the watersheds, but was inversely significant for Na+, and was possibly direct for K+ in a few instances. The budget for dissolved cations was calculated from determinations of input (cation concentration times volume of precipitation) and output (cation concentration times volume of runoff.) During 1963—64 the average inputs in kg/ha were 3.0 Ca++, 0.7 Mg++, 2.5 K+, and 1.0 Na+, while the output averaged 8.0 Ca++, 2.6 Mg++, 1.8 K+, and 5.9 Na+. During 1964—65 the values were: input, 2.8 Ca++, 1.1 Mg++, 1.8 K+, and 2.1 Na+; and output, 3.9 Ca++, 1.8 Mg++, 1.1 K+, and 4.5 Na+. Assuming that the vegetation is near dynamic equilibrium, the net losses of Ca++, Mg++, and Na+ represent conservative measurements of geochemical weathering in the system. The K+ budget is probably near balance.
Construction and Performance of a Temperature‐Gradient Bar and Chamber
Authors: Barbour M. G. , Racine Charles H.
Published: May 2006

An inexpensive temperature—gradient bar and chamber for use in studies of seed germination and root growth is described. Aluminum troughs and a bar, surrounded by insulation and heated and cooled at their ends by water baths, form the floor of a chamber. A plexiglass top permits illumination by overhead light banks. The temperature gradient may be adjusted to any range within the limits of 10° and 50°C. The linearity and stability of the bar gradient, and the presence of temperature and humidity gradients in the chamber air above the bar, are discussed.
Selected Nutrients in Mule Deer Browse Plants
Authors: Short Henry L. , Dietz Donald R. , Remmenga Elmer E.
Published: May 2006

Nine plant species believed to be important to mule deer (Odocoileus hemionus) on the Cache la Poudre range of Colorado were collected at four seasons during 1961, from five study areas which varied in altitude from 6,400 to 10,300 ft. Eleven chemical components were analyzed for each of the 77 plant samples. In a deciduous species (Purshia tridentata) the percentage dry matter and crude fat, and the caloric content varied from high autumn—winter levels to low spring—summer values; and beta carotene and percentage protein, ash, phosphorus, potassium, calcium, sodium, and magnesium levels varied from low autumn—winter values to high spring—summer values. In an evergreen species (Juniperus scopulorum) the seasonal changes in plant chemistry were not so pronounced. Major variations in the measured components were attributable to two causes in the following order: (1) differences in nutrient levels between species; (2) differences in nutrient levels measured for one plant species at the four seasons. Minor variations were evident within single species when sampled in a specific season at different areas throughout its range. The normal and predictable variation in plant chemistry caused by seasonal changes in plant phenology and physiology and physiology has important implications to the nutrition and physiology of deer.
Structure and Composition of Foothill Woodland in Central Coastal California
Authors: White Keith L.
Published: May 2006

Structure and species composition were sampled in 49 stands of foothill woodland in the vincinity of Hastings Reservation. Most of the stands were nearly pure blue oak (Quercus Douglasii). There was an average of 207 trees per acre, but an average of only 75 saplings per acre. The majority of saplings were blue oaks so that blue oak is not being replaced by other species. Fire and livestock grazing have probably not limited blue oak reproduction recently, but deer browsing limits the growth of many oak seedlings. Annual right counts on stumps showed that the majority of blue oak trees originated over a relatively short period from approximately 1870 to 1890, a dynamic period of land use in the study area, but the factor or factors that accounted for this flush of oak reproduction cannot be determined.
Ecology of Vertebrate Animals in Relation to Chaparral Fire in the Sierra Nevada Foothills
Authors: Lawrence George E.
Published: May 2006

Chaparral fire brings decided changes in the species composition and density of both plant and animal populations in the Sierra Nevada foothills. Some species decrease whereas others increase following a burn, but not species is totally eliminated, nor is there any apparent diminution of total life on a burn after plant growth resumes. These conclusions were reached in the course of a 4—year study of adjoining burnedand unburned areas near Glennville, Kern County, California. Field work began in 1953 at which time study plots were selected and plant and vertebrate population were censused. A year later part of the study area was burned, and ensuing investigation compared populations on the burned and check areas for a period of 3 years, terminating in 1957. At the time of the fire, temperatures were recorded in sites both above and below ground, and the actions of animals were observed. There was very little evidence of direct mortality among any of the vertebrates, most of them escaping the heat in one way or another. The woodrat was perhaps the most vulnerable species because of its dependence on houses made of dry twigs. However, in the bare ash after the fire many species were severely exposed to predation, and populations of the most small mammals and some brush—dwelling birds decreased rapidly. Predatory birds and mammals increased, as did some seed—eating birds that found good foraging on the exposed earth. When the rains stimulated new plant growth, a very different habitat developed in the area of burned chaparral. Most of the original trees sustained little damage, although the pitchy digger pines were largely eliminated. However, the extensive brush stands were reduced by almost 90%, and there was a corresponding increase in invading grasses and forbs. Birds and mammals that normally exhibit a strong preference for chaparral habitat were substantially reduced in numbers in the years following the burn. Conversely, some of the birds that normally prefer grassland or oak woodland increased in number. The fire resulted in an overall increase in densities of nesting birds. None of the small mammals increased in numbers but some of the larger predators, such as the coyote and badger, moved into the burn during the months following the fire.
Observations on the Social Behavior of the Land Hermit Crab, Coenobita Clypeatus (Herbst)
Authors: Hazlett Brian A.
Published: May 2006

The social interactions of Coenobita clypeatus resemble those of marine hermit crabs in many ways. Stereotyped movements of the chelipeds and ambulatory legs were often executed as two crabs approached each other. Idividuals also have a repertoire of shell fighting behavior patterns, including rotating movements by the attacker and production of a chirping sound by the defender.
New Observations on Reproductive Behavior in the Milliped Marceus Annularis (RAF.)
Authors: Shaw George G.
Published: May 2006

Oviposition and rearing of nyumphs have been achieved in laboratory populations of this milliped. They were maintained on year—old deciduous leaf litter. Single eggs are oviposited into capsules at the anterior of a female and then passed posteriorly where they are taken into the rectum. The capsule is dried in the rectum and then deposited on the substratum.
Pattern Analysis by Regression
Authors: Yarranton G. A.
Published: May 2006

A method of analyzing spatial pattern by serial regression is proposed. It involves regression of species frequencies on other frequencies of the same species recorded at increasing intervals of distance from the "dependent" record. If the regression coefficients are plotted against distance, positive peaks indicate the distance between individuals or clumps of the species, and negative peaks indicate the distance between clumps and spaces. The method is contrasted with the analysis of variance approach first proposed by Greig—Smith. Pattern analyses of crustose lichens on a limestone cliff are employed to illustrate application of the method and to facilitate comparison with the analysis of variance method.
Size, Mass, and Caloric Content of Particulate Organic Matter in Old‐Field and Forest Soils
Authors: Malone Charles R. , Swartout Margaret B.
Published: May 2006

Particulate organic matter of various size fractions larger than 44 μ in diameter was extracted from old—field and forest soils by flotation in aqueous solutions of magnesium sulfate. Extracted ash—free organic material comprised about 0.6% of the dry weight of both soils and from 15—20% of all the organice matter present in the soils. Particulate organic matter less than 44 μ in size accounted for 70% of the organic matter, the remaining 10—15% being water soluble. In the old—field soil, a direct relationship existed between caloric values and particle sizes with the exception of particles between 44—105 μ in size. Relationships between size and energy content of organic particles in the forest soil were not as clearcut, since several smaller size components in the upper 10 cm of the soil had greater caloric contents than larger sizes. The data are discussed in relation to decomposition processes and heterotrophic production in soil ecosystems.
Climatic Changes in Southern Connecticut Recorded by Pollen Deposition at Rogers Lake
Authors: Davis Margaret B.
Published: May 2006

Rates of deposition of pollen grains throughout late— and postglacial time were determined from the pollen concentration in radiocarbon—dated sediment. Changes by a factor of 5 or more for all except rate pollen types from one level to the next were considered significant indication of changes in the pollen input to the lake, reflecting changes in the pollen productivity of the surrounding vegetation. Low pollen deposition rates in the oldest sediments reflect the prevalence of tundra vegetation between 14,000 and 12,000 years ago. An increase in the rate for tree pollen occurred 12,000 years ago, when boreal woodland became established. The rates continued to increase until a sudden sharp rise for white pine, hemlock, poplar, oak, and maple pollen 9,000 years ago marked the establishment of forest, similar perhaps to modern forests of the northern Great Lakes region. Pine pollen rates decline 8,000 years ago, and deciduous tree pollen became dominant. Ragweed pollen was deposited at relatively high rates 8,000 years ago, reflecting changes in the vegetation associated with the "prairie period" recorded in the Great Lakes region at this time. Subsequent changes in pollen deposition rates reflect the immigration of beech (6,500 years B.P.), hickory (5,500 years B.P.), and chestnut (2,000 B.P.) to southern Connecticut. During the past few hundred years pollen deposition rates reflect changes in the vegetation caused by disturbance by European settlers. Throughout much of postglacial time the pollen assemblages deposited at Rogers Lake are different from assemblages known from modern sediment. This makes climatic interpretation difficult and suggest that the forest associations of the region as they are recognized now are of quite recent origin.
Carbohydrate Reserves in Mertensia Arizonica as Related to Growth, Temperature, and Clipping Treatments
Authors: McDonough Walter T.
Published: May 2006

Growth of aerial stems and carbohydrate content of the caudices of Mertensia arizonica var. Leonardi were determined at several stages of development under controlled conditions. Carbohydrate analyses were made similarly for field—grown plants, with and without single clipping treatments at several stages of development. Best growth and accumulation of carbohydrate occurred at controlled temperature alternations of 20°C (day) and 10°C (night). The trends in carbohydrate levels were the same for growth under controlled conditions and in the field: an initial decrease during early vegetative growth followed by an increase to the time of senescence of aerial stems. Single clipping treatments had no effect on carbohydrate levels nor on the timing of utilization and storage.
The Reproductive Cycle of Daphnia in An Arctic Pool
Authors: Stross R. G. , Kangas D. A.
Published: May 2006

The reproductive cycle of Daphnia middendorffiana living in an arctic pool and an arctic lake is essentially the same. An overwintering generation produces one brood of young before shifting to produce broods of embryos which enter diapause. The pool warms more rapidly than the lake and has twice the number of day—degrees above 0°C. The higher temperature acts only to accelerate the development rate of the Daphnia, and the reproductive shift occurs in mid—July rather than in late August. The restriction of population growth to one brood of young in the warmer pool and colder lake is used to illustrate the hypothesis that arctic temperature influences productivity by controlling life cycle rather than by restricting rates of metabolism.
Size of Breeding Colony Related to Attraction of Mates in a Tropical Passerine Bird
Authors: Collias Nicholas E. , Collias Elsie C.
Published: May 2006

Field observations and counts of nests and birds present were made for 18 colonies of the Village Weaverbird, Ploceus (Textor) cucullatus, in north—west Senegal during the breeding season of 1967. In this gregarious and polygynous species, the male weaves the nest and then endeavors to attract the female to the nest by means of special displays and vocalizations. Breeding colonies with fewer than 10 males had a much smaller proportion of females resident in the colony at or near the peak of colony growth than did larger colonies (chi—square test, P = .018). The species is near the northern border of its range near the Sahara in this region and presence or absence of sufficiently large trees is at times a crucial factor limiting local distribution of colonies. Although large trees in general tend to have larger colonies than do small trees, success of a colony in attracting females was correlated much more with number of males and nests than with size of tree. It is concluded that the evolution of gregarious breeding in this species was in part due to the increased efficiency of attracting mates that results from colony life.
Carbon Dioxide Retention: A Mechanism of Ammonia Tolerance in Mammals
Authors: Studier Eugene M. , Fresquez A. A.
Published: May 2006

When guano bats, Tadarida brasiliensis, inhale ammonia in air mixtures, carbon dioxide is passively retained in sufficient amounts to neutralize alkali excess resulting from increased blood ammonia levels. There is no change in blood carbon dioxide levels in house mice, Mus musculus. Little brown bats, Myotis lucifugus, are intermediate in this respect. Passive carbon dioxide retention is clearly related to ammonia tolerance in these mammals.
Ecotypic Variation in Deschampsia Caespitosa (L.) Beauv. from Colorado
Authors: Ward Richard T.
Published: May 2006

Plants of tufted hairgrass (Deschampsia caespitosa (L.) Beauv.), collected from 12 locations in Colorado, were grown in a common garden at Fort Collins and studied for ecotypic differentiation. Phenological response was related especially to elevation and somewhat to latitude. Plants from 11,000 ft were approximately 1 month earlier in anthesis than those from 9,000 ft, while those from the lower elevations had similar leaf lengths but longer culms than those from 11,000 ft. Great differences in phenologic timing were observed for hairgrass in the native habitats of the Fall Mountain area, but the transplants showed essentially no differences in the common garden. Ecotypic differentiation and ecophenic plastisticity are therefore demonstrated to be important attributes in the hairgrass populations of Colorado.
Evaporative Water Losses of Some Small Australian Lizards
Authors: Dawson William R. , Shoemaker Vaughan H. , Licht Paul
Published: May 2006

Water loses of small (1.5 to 4.6 g) representatives of three species of Australian lizards, Amphibolurus ornatus (Agamidae), Gehyra variegata (Gekkonidae), and Sphenomorphus labillardieri (Scincidae), were determined from weight losses incurred by the animals in a dry atmosphere. In one set of experiments conducted at 20°C, the animals were unrestrained in their chambers.The rates of total water loss by A. ornatus, G. variegata, and S. labillardieri averaged 1.9 g (100g day)—1, 3.0 g (100g day)—1, and 6.8 g (100 day)—1, respectively. These rates primarily reflect the evaporative loss of water. The differences among them did not appear to result from differences in activity, for the metabolic rates of S. labillardieri and A. ornatus both approximated 0.07 cc O2 (g hr)—1. In a second set of experiments conducted at 20 and 30°C, the water losses of restrained individuals were compartmentalized. The total loss by A. ornatus averaged significantly lower than that by G. variegata and S. labillardieri at both temperatures. This resulted primarily from differences in pulmonary water loss among the three lizards. At 20°C cutaneous loss accounts for 70% of the evaporative loss by A. ornatus and variegata and 41% of that by S. labillardieri. The percentages are somewhat lower at 30°C owing to the greater effect of temperature on pulmonary than on cutaneous loss. The distributions of these three lizards correlate well with these observations on water loss, A. ornatus and G. variegata reaching hotter and drier sections of Australia than S. labillardieri.
The Origins, Spread, and Consolidation of a Floating Bog in Harvard Pond, Petersham, Massachusetts
Authors: Swan J. M. A. , Gill A. M.
Published: May 2006

The mode of development of an extensive floating bog (400 m by 400 m) at the north end of Harvard Pond, an artificial lake, was studied by careful examination and local dissection of the bog mat within a 32—m by 16—m plot. Excavations were also made at the bog margin. The origins, spread, and consolidation of the floating mat are largely explained by the growth characteristics of one ericaceous shrub, Chamaedaphne calyculata (L.) var. angustifolia (Ait.) Rehd. A wetland forest was cut about 1830, and Chamaedaphne, first invaded the tree stumps between 1830 and 1890 (when they were located in a sedge meadow). Harvard Pond was formed about 1890, and the floating mat has developed between 1890 and 1968 (by the lateral spread of Chamaedaphne across the water surface to occupy the intervening spaces between stumps). Bog—advance rates were estimated from photographs and from annual growth increments for the shrub. Expansion appears to have been rapid (up to 6.3 cm/year or 2.5 inches/year).
Spatial Homogeneity: Statistical Analyses of Unispecies and Multispecies Populations of Foraminifera
Authors: Buzas Martin A.
Published: May 2006

In Rehoboth Bay, Delaware, 16 stations, each 10 m apart in a 4—by—4 grid, were sampled with 5 replicates. The living individuals of four species of Foraminifera were enumerated. Analyses of variance of unispecies populations indicate that only one relatively rare species has homogeneous densities. Analyses of differences between stations by the S—method indicate that one of the three species with inhomogeneous densities has a high or pitch at one station. Although two other species have inhomogeneous densities, none of the contrasts indicate any patches within the study area. Multivariate analysis of variance of the multispecies population indicates that the mean vectors of densities are inhomogeneous. Canonical variate analysis shows that this inhomogeneity is due to high species densities at one station. Efficient utilization of habitat space by unispecies populations probably accounts for the homogeneity of the multispecies population at the remaining 15 stations.
Seed Predation and Dormancy in the Population Dynamics of Avena Fatua and A. Barbata
Authors: Marshall D. R. , Jain S. K.
Published: May 2006

Estimates of seed loss due to animal predation in Avena fatua and A. barbata over a number of sites in the California annual—type grasslands varied from 0% to 65% of the total seed load. Avena species showed complex patterns of variation in germination both between and within populations. Counts of seedling deaths due to precocious germination in nature suggest that the observed variation in germination provides insurance against seedling losses due to somewhat erratic fall rains. These factors are significant in regulation of Avena populations.
Amino Acid, Protein, and Caloric Content of Vascular Aquatic Macrophytes
Authors: Boyd Claude E.
Published: May 2006

The percentage of each amino acid in the total protein was remarkably similar in 11 species of vascular aquatic plants, as well as in the same species from different sites and the same species at different stages of maturity. Total protein concentrations in the various samples differed greatly, however; such differences may have great importance in food webs. Caloric values for all samples were relatively uniform.
Mortality of Estuarine Animals Due to Cold on the Georgia Coast
Authors: Dahlberg Michael D. , Smith Frederick G.
Published: May 2006

Mortality of some species of estuarine fishes and invertebrates along the Georgia coast was associated with the presumably caused by abnormally cold water temperatures in January 1970. Mortality was low in most estuarine species but high in star drum and white shrimp in the Duplin River and Doboy Sound. Affected star drums and silver perches became weakened and lost their equilibrium. Most of these apparently died from suffocation or freezing when they were left stranded in the marsh by receding ebb tides.
Drought‐Associated Mortality of Range Grasses in South Texas
Authors: Chamrad Albert D. , Box Thadis W.
Published: May 2006

The effects of a 2—year drought on native grasses in South Texas were investigated on the Welder Wildlife Foundation Research Area during the summer of 1963. The percentage mortality on Victoria clay, Nueces fine sand, and Miguel find sandy loan was determined for seacoast bluestem (Andropogon scoparius Michx. var. littoralis (Nash) Hitch.), silver bluestem (Andropogon saccharoides Swartz var. longipaniculata Gould), filly panicum (Panicum filipes, Scribn.), buffalograss (Buchloe dactyloides (Nutt.) Engelm.), Pan American balsamscale (Elyonurus tripsacoides Humb. and Bonpl.), and brownseed paspalum (Paspalum plicatulum Michx.). Mortality ranged from an average low of 3407% for silver bluestem on Victoria clay to an average high of 76.8% for seacoast bluestem on Miguel fine sandy loam. Differences in percentage mortality between soils and between species on given soil types were highly significant. Mortality among individual clones ranged from 0% to 100%. In some instances a significant positive correlation existed between size of grass clones and percentage mortality. As diameter of clones increased, percentage mortality increased.
Respiration and Phosphorus Excretion in Some Marine Populations
Authors: Satomi Masako , Pomeroy Lawrence R.
Published: May 2006

The rate of oxygen consumption and the rate of excretion of phosphate and of total phosphorus were simultaneously measured in No. 2—net plankton, oysters, and sea anemones. There was a high positive correlation between respiration and phosphate excretion, with a characteristic O:P ratio for all plankton populations but different ratios for the other organisms. Zooplankton excrete a high proportion of organic phosphorus and have a low O:P ratio, which suggests that they do not oxidize food completely. From observations such as these it is possible to estimate phosphorus flux through a population from respiration data, or the reverse.
The Relationships between Inorganic Phosphate Uptake and Oxygen Consumption by Daphnia Schodleri Sars
Authors: Parker Richard A. , Helm Ronald
Published: May 2006

Twenty—six experiments were conducted in which phosphate uptake and oxygen consumption by Daphnia schodleri Sars from membrane—filtered lake water were measured concurrently at three densities (25/, 50/, 100/100 ml). Assuming linearity, uptake was related inversely to density (P < 0.05), directly to phosphate concentration (P < 0.005), and directly to oxygen consumption (P < 0.006).
Relationship Among the Forest Types of Indiana
Authors: Schmelz Damian V. , Lindsey Alton A.
Published: May 2006

The 36 least disturbed hardwood stands in Indiana were selected for analysis of the characteristics and interrelationships of the five forest types. The types were defined by the species importance sums for the four species—groups: oak—hickory, beech—maple, other upland mesophytic species, and lowland—depressional species. From the matrix of stand similarities derived by applying Motyka's coefficient to species importance values, relationships among the five forest types were indicated by cluster and ordination analyses. Both methods grouped stands of three types as extremes (oak—hickory, beech—maple, and lowland—depressional) and two mixed types as intermediates (western mesophytic and mixed woods). Within each extreme type some variant stands represented gradations toward another type. Edaphic controls of the forest types in Indiana are indicated by the patterns of the ordination distribution of substrate factors: drainage profiles, available moisture, permeability, texture of the A horizon, source of the parent material, pH of the B horizon, and degree of development of the soil.
Efficiency of Net Primary Production Based on Light Intercepted During the Growing Season
Authors: Botkin Daniel B. , Malone Charles R.
Published: May 2006

Net primary production of a 1—year—old field on the New Jersey Piedmont was 1.08 kcal/cm2 or 10% of the radiant energy (0.4—0.7 @m) intercepted by the vegetation from the last spring frost to the latest date a dominant producer reached its peak standing crop biomass; 3.8% of the energy available above the vegetation during the same period; 7.5% of the energy intercepted from the last spring frost to the first fall frost; 3.1% of the energy available above the vegetation during this period; and 1.8% of the energy available yearly. These results are among the first direct determinations of efficiency of net primary production based on interception of radiant energy under field conditions. Interception, the difference between radiant energy available above and below the vegetation, was measured with the Yellott solarimeter, whose small size made possible below—vegetation measurements with minimum disturbance to the cover. Net primary production for shoots was determined on a species basis by the short—term harvest method. Root production was estimated on a community basis by extracting roots from soil samples by a soil—dispersion and chemical flotation technique.
Soil‐Vegetation Relationships in the Shadscale Zone of Southeastern Utah
Authors: West Neil E. , Ibrahim Kamal I.
Published: May 2006

Four distinctive units of landscape, soils, and vegetation occurring in a selected area within the shadscale zone of southeastern Utah are designated by the dominant plant species as the Atriplex confertifolia/Hilaria jamesii, Atriplex nuttallii var. nuttallii/Hilaria jamesii, Atriplex nuttallii var. gardneri—Aster xylorhiza, and Atriplex corrugata habitat types. The Atriplex confertifolia/Hilaria jamesii community occurs only on level pediment remnants where coarse—textured and well—developed soil profiles have been derived from sandstone gravel. Soils under this community were non—alkali throughout the profile. They were nonsaline in the surface 2.5 ft but saline at greater depths. A distinct lime zone 9.16 inches thick occurs from 15 to 29 inches below the soil surface. The Atriplex nuttallii var. nuttallii/Hilaria jamesii community occurs on eroded prediment slopes where a shallow A1 vesicular horizon overlies a Ccs massive gypsiferous horizon and altered bedrock of Mancos shale. These profiles are loamy and non—alkali throughout. They are non—saline in the surface 15 inches but saline at greater depths. A gypsiferous horizon 7—17 inches thick occurs from 2 to 4 inches below the soil surface. The Atriplex nuttallii var. gardneri—Aster xylorhiza community occurs on lower Mancos shale badlands. The soil profiles found here are typically fine textured and non—alkali throughout. They are non—saline in the surface 12 inches but saline at greater depths. The Atriplex corrugata community is found in alluvial basins where materials from the other three habitat types have been deposited over Mancos shale. The soils of this habitat type are heavy textured and saline—alkali throughout the profile.
Effect of Soil Salinity on Germination and Survival of Some Steppe Plants in Washington
Authors: Choudhuri G. N.
Published: May 2006

Salt tolerance at germination and the capacity of the established plants to endure gradual salinization of the soil were studied in Agropyron spicatum, Artemesia tridentata, Elymus cinereus (from saline and non—saline habitats), Lepidium perfoliatum (from saline and non—saline habitats), and Typha latifolia. Percentage germination decreased with increasing salinity. All species were less tolerant of salinity at germination than they were at the seedling stage, if salinization of the culture medium was gradual. An abrupt rise in salinity resulted in death of all species. Of all the species tested Lepidium perfoliatum demonstrated the greatest potential for ontogenetic osmoregulation. In general, the response of the established plants corresponds well with the species behavior in the field. Adverse environmental factors, such as a predominance of Na2CO3, probably results in restricted distribution of Typha latifolia and also keeps Agropyron spicatum from colonizing saline areas. Seeds of Lepidium perfoliatum from saline habitats were more tolerant of salinity than those from non—saline habitats, indicating an ecotypic specialization in this species. Populations of Elymus cinereus from saline and non—saline habitats did not differ in this respect.
Patterns of Variation Among Climatic Races of Red‐Osier Dogwood
Authors: Smithberg Margaret H. , Weiser Conrad J.
Published: May 2006

Red—osier dogwood (Cornus stolonifera Michx.) clones were collected from 21 locations in the natural range of the species and grown in a uniform plot at St. Paul, Minnesota, to determine the extent and nature of geographic variation. Significant variations in plant form and growth rate were noted. Genetic influence among the climatic races was apparent in autumnal phenological events such as onset of rest, change of bark color, and leaf abscission. These events were related to provenance features such as winter minimum temperatures, length of growth season, and to a lesser extent to latitude. The time at which cold hardening began in the autumn differed among clones, but no differences were noted in the ultimate degree of hardiness in midwinter. Spring bud break and flowering occurred at about the same time in all clones, while the loss of red bark color varied. Controlled environment and field tests indicated that photoperiod was the prime factor triggering autumn phenomena, while temperature was most important in the spring.
A Precis on Energetics of the Old‐Field Mouse
Authors: Caldwell Larry D. , Connell Clyde E.
Published: May 2006

Old—field mice (Peromyscus polionotus) are as much as 42% less active on clear moonlight nights according to live and snap—trap data. Since food is not always cached in the nest, old—field mice may at times rely upon forms of stored metabolic energy when foraging is not possible. We analyzed 254 mice for metabolizable body fat and 32 for caloric value of stomach contents. The 5 Kcal of metabolizable body fat and 2.8 Kcal of metabolizable stomach contents would last an inactive mouse for at least 2.8 days at basal levels if foraging were to be stopped entirely. The breeding season is evidently a period of increased metabolism for both sexes since body fat reserves are lowest at this time. The availability of arthropod and especially seed foods was seemingly an important factor in counteracting the metabolic drain of breeding as reflected by low body fat reserves. During the breeding season fat reserves of both sexes declined to half of the nonbreeding level. By contrast, reproductively active individuals which were held captive for 3 weeks and supplied with ad libitum food increased mean body fat from 2—4 fold above the levels found in natural populations. Postpartum females seem to have the least amount of body fat because of the high energy demands of lactation. Lactating females, in contrast to other mice, compensate for the necessity of higher energy storage by feeding more intensively (a two fold increase in stomach capacity).
Radiation Doses Sustained by Lizards in a Continuously Irradiated Natural Enclosure
Authors: Turner Frederick B. , Lannom Joseph R.
Published: May 2006

Desert lizards occupying a 20—acre experimental facility continuously exposed to gamma radiation sustain tissue doses which are less than the cumulative free—air dose. Vegetation and terrain afford some shielding, but time spent below ground is the major source of protection. We estimate that, in the course of a year, tissue doses sustained by Uta stansburiana are from 0.3 to 0.6 of the cumulative free—air dose, and that about 1/3 of the total dose is experienced between June and August. Cnemidophorus tigris spends less time above ground, and sustains annual doses representing only about 0.1 to 0.2 of total incident gamma radiation. The dose experience of Crotaphytus wislizeni is intermediate to the other two species. Dose regimes experienced by Uta stansburiana in the experimental area are not acutely lethal.
Avian Dispersal of Plants in Panama
Authors: Olson Storrs L. , Blum Kurt E.
Published: May 2006

Seeds of various species of plants taken from birds collected in Panama were planted and observed for germination. Viable seeds were found in all parts of the bird digestive tract. Especially preferred by birds were the fruits of Cecropia peltata L. The seeds of this important plant exhibited outstanding viability after having passed through the alimentary canal.
Light Relations of Psoralea Subacaulis T. & G. (Leguminosae)
Authors: Baskin Jerry M. , Quarterman Elsie
Published: May 2006

Plants of Psoralea subacaulis were grown under three light regimes, 15, 40, and 100% full sunlight, and the photosynthetic rates were measured at 18° and 25°C at various light intensities and that it does poorly in the shade. Field observations that P. subacaulis is an obligate heliophyte are thus verified.
Effects of Crowding on the Agonistic Behavior of the Hermit Crab Pagurus Bernhardus
Authors: Hazlett Brian A.
Published: May 2006

The effects of increased population density were studied in the hermit crab Pagurus bernhardus. Without periods of adjustment between increments of population increase, the number of aggressive interactions increased rapidly, and the proportion of fights decided by physical contact increased significantly as density was increased. With period of adjustment, there were no marked increases in aggression as density increased.
Nutrient Limiting Factors in an Arctic Tundra Pond
Authors: Kalff J.
Published: May 2006

The relationship between rates of phytoplankton photosynthesis and nutrient and growth factor deficiencies was investigated by the nutrient enrichment bioassay technique in a small tundra pond at Barrow, Alaska, Phosphate, nitrate, and ammonia deficiencies limited photosynthesis after the onset of a period of high sustained growth. Toward the end of this period, additional deficiencies for one or more trace elements and growth factors, with vitamin B(12) being one deficient growth factor, were noted. No nutrient and growth factor deficiencies were found during the subsequent period of low carbon incorporation. Interactions between nutrients as well as between nutrients and light were found to complicate the recognition deficiencies. The utility of the enrichment bioassay in determining nutrient and growth factor deficiencies is briefly discussed.