bluuebunny/crossref_metadata_2025 huggingface dataset:
Bioenergetics of the Woodlouse Tracheoniscus Rathkei Brandt in Relation to Litter Decomposition in a Deciduous Forest
Authors: White Joseph James
Published: May 2006

In feeding tests conducted under laboratory conditions, the woodlouse Tracheoniscus rathkei Brandt showed a preference for the leaves of pawpaw (Asimina triloba), over those of suger maple (Acer saccharum), hackberry (Celtis occidentalis), red oak (Quercus rubra), and bur oak (Quercus macrocarpa). Observations of T. rathkei in experimental gradients show that its behavior is such as to insure continuous activity until a habitat is found that meets its requirements for contact, darkness, low saturation deficit and low temperature (5°—20°C). T. rathkei was able to maintain copper balance without resorting to coprophagy. Differences between copper intake in food and copper loss in feces were accounted for by changes in body copper. The biomass of the population in a representative deciduous forest fluctuates from 0.09 to 0.35 g/m2 between January and September and averages 0.208 g/m2. This average is equivalent to 635.5 g—cal/m2 (1 gram woodlouse = 3.521 g—cal). The energy flow through this woodlouse population is calculated as gross energy intake, 2,799; excretory energy, 1,871; and metabolized energy, 928 g—cal/m2/year. Assuming a caloric equivalent for paw—paw leaves of 4,625 g—cal/g, and an efficiency of assimilation of 33 per cent for the woodlice, the annual consumption of leaves is 0.605 g/m2/year. The low efficiency of assimilation results in the consumption of a relatively large quantity of leaf litter, which passes rapidly through the gut, making available a large fecal substrate favorable for other organisms. Woodlice contribute to the energy flow in the ecosystem, not soi much by being preyed upon by organisms in higher tropic levels as by their contribution to the mechanical breakdown of leaf litter.
Spatial Pattern of Shrubs on a Desert Plain in Ethiopia
Authors: Beals Edward W.
Published: May 2006

The distribution of the shrub Cadaba rotundifolia on a sandy plain showed a complex pattern which apparently included a trend towards aggregation, and within areas of higher density a strong trend towards regularity. The latter may result from competition for water, and the former from seed dispersal. Of the various methods of analyzing departure from randomness, the ratio, observed variance to expected variance, and the index of dispersion associated with it, were the most sensitive.
Algal Diversity in Several Thermal Spring Effluents
Authors: Kullberg Russell G.
Published: May 2006

Several thermal spring effluents of western Montana were studied for agal diversity along temperature gradients. Individual communities found at intervals along the effluents were sampled to determine for each species the number of individuals and the volume. Dominance—diversity curves present the data to emphasize the individual communities; population curves and diversity index curves emphasize the gradient communities.
Equitability and Resource Limitation
Authors: Pulliam H. Ronald , Odum Eugene P. , Barrett Gary W.
Published: May 2006

It is suggested that the equitability concept of Lloyd and Ghelardi provides an approach to resolving the question of resource limitation in a specific field situation. The high equitabilities of predaceous insect groups in an annual grassland community indicated that these populations were food limited, whereas the low equitabilities of the herbaceous insects indicated that they were limited by some other factor not directly involved in competition. The increase in equitability of the spiders (all species of which are predatory) during the growing season was tentatively explained on the basis that reaching a resource—limited equilibrium in relative abundances required more time because of the relative immobility of species in this component. These data also demonstrated how the relative abundances of species can undergo a history of adjustment during seasonal succession.
Parasitization of Acyrthosiphon Pisum by Aphidius Smithi, A Density‐Dependent Process in Nature. (Homoptera: Aphidae) (Hymenoptera: Aphidiidae)
Authors: van den Bosch Robert , Schlinger Evert I. , Lagace Charles F. , Hall Jack C.
Published: May 2006

The interrelationships between the pea aphid, Acyrthosiphon pisum (Harris) and its parasite, Aphidius smithi Sharma & Subba Rao, were studied in alfalfa fields at Riverside, California from July 1961 to July 1962 and at Pala Mesa (San Diego County), California from July 1962 to July 1963. Response of aphidius to changes in Acyrthosiphon density was repeatedly in each plot. However, in both areas during much of the year the wasps' density dependence was obscured by certain factors in the environment. Weather conditions, agricultural practices, and competition from fungus disease appeared to be the most important of these factors. In each area, though, in late spring when conditions were apparently optimum for parasite activity the wasp evinced a clear cut response to increasing aphid density and quickly overwhelmed the host population. The possible relationships of the findings of the present study to the density—dependent phenomenon in general are briefly discussed.
Salt‐Marsh Vegetation of Upper Newport Bay, California
Authors: Vogl Richard J.
Published: May 2006

The salt—marsh vegetation of Newport Bay was separated into littoral and maritime zones and was sampled quantitatively for frequency of occurrence and cover. The littoral zone (marsh proper) was divided into a narrow lower belt covered by Spartina foliosa, a broadest middle band dominated by Batis maritima and Salicornia virginica, and a narrowest upper strip influenced by Salicornia virginica and Monanthochloe littoralis. The maritime zone consisted of a bluff community composed of Suaeda californica and Salicornia subterminalis, or a dune associate pioneered by Oenothera cheiranthifolia and Heterotheca grandiflora. Nine species, principally Gramineae and Chenopodiaceae, dominated the marsh. Salicornia virginica accounted for the highest total average frequency and cover. Additional important species were Suaeda californica, Batis maritima, and Spartina foliosa. The plant community was extremely simple in the lowest areas (four species) and graded to a more complex, yet relatively simple plant community in the highest regions of the marsh (15 species). Correspondingly, the lower zones had sparse vegetational cover and the higher zones supported heavier growth, both in size and numbers of individuals. Although the marsh was subjectively divided into zones, individual species could not be readily segregated into zones since the frequency of each species varied along environmental gradients to produce a vegetational continum.
Fish Eggs as the Apparent Sole Food Item for a Genus of Sea Snake, Emydocephalus (Krefft)
Authors: Voris Harold K.
Published: May 2006

The stomachs of five Emydocephalus annulatus Krefft, and two Emydocephalus ijimae Stejneger, have been found to contain fish eggs only. The eggs being preyed upon are demersal and can be traced to bottom—dwelling inshore species of at least two families, Gobiidae and Blenniidae. In conjunction with the diet of fish eggs, the dentition of Emydocephalus is greatly reduced. The dentary and palatine bones are toothless and the maxilla bears no teeth other than fangs. The pterygoid has many very small teeth.
Salt Tolerance of Plants Growing in Saline Areas of Kansas and Oklahoma
Authors: Ungar Irwin A.
Published: May 2006

Analyses of soil salinity in Kansas and Oklahoma marshes indicate that the most salt—tolerant species have the widest salinity tolerance and can survive under low as well as high salinities. The less tolerant species are limited in their distribution to low and nonsaline areas.
Life History Pattens of the Littoral Gastropods Shaskyus Festivus (Hinds) and Ocenebra Poulsoni Carpenter (Prosobranchia: Muricidae)
Authors: Fotheringham Nick
Published: May 2006

Monthly recaptures of marked individuals in intertidal populations of the predatory gastropods Shaskyus festivus and Oceanebra poulsoni for 39 months near La Jolla, California, show annual variation in growth, reproduction, and recruitment rates consistent with the conclusion that the snails experienced only 1 successful year in 3. Eggs are deposited in capsules from March through July, and free—swimming veligers are released in 3 to 4 weeks. More than 99% of the mortality occurs in the plankton or during settlement. The major predator on the adults, the crab Cancer antennarius, annually destroys less than 1% of the adults Shaskyus and less than 2.5% of the adult Ocenebra. After settlement, Shaskyus can expect to live for more than 10 years, and Ocenebra for more than 9 years. The adult mortality rate was generally highest during the reproductive season but lowest in 1969, when the greatest reproductive effort was observed. Marked individuals of both species have been found in breeding aggregations in more than one season, suggesting iteroparity. Shell growth rates decreased and mortality rates increased as shell length increased in both species. The sex ratio of Shaskyus from 25.0 mm to 44.9 mm did not differ significantly from 1:1. The proporations of female Ocenebra longer than 14.9 mm increased as shell length increased. The determination of sex in smaller size classes was uncertain because many smaller males were probably immature and lacked penises. Sexual differences in growth and mortality rates were probably responsible for the paucity of males in the larger size classes. No evidence for sex reversal was found in repeated sex determinations of marked snails.
Oak Regeneration in the Upper Carmel Valley, California
Authors: Griffin James R.
Published: May 2006

Acorn germination and seedling survival were studied in three species of foothill woodland oaks. Quercus douglasii and Q. lobata acorns matured in October. These nondormant acorns germinated quickly at favorable temperatures. Quercus agrifolia acorns matured later and germinated more slowly. Acorns placed on the surface of a south—aspect plot lost viability. On a north—facing plot they survived autumn heat and germinated during the winter, but rooted poorly. Acorns buried on either aspect germinated well. Burial by birds and squirrels, important in regeneration, insulates acorns from autumn heat, partially hides them from animals, and ensures rooting. Quercus douglasii seedlings had the greatest drought tolerance. In grass cover on a south—facing soil even they can survive their first summer only during wet years. On north aspects seedlings of several species can survive grass competition over a broader range of climatic conditions. Deer and pocket gophers are important in eliminating seedlings that survive the summer drought.
Effect of Salinity on Growth of a Salt Marsh Grass
Authors: Phleger Charles F.
Published: May 2006

The coastal salt marsh grass, Spartina foliosa Trin., was grown in nutrient solution at different salinites (0%—125% sea water; sea water =33%) for 8 weeks. Growth and survival was greatest in fresh water although the plant grows in sea wate in its natural habitat. Protein (17.9% ± 0.8%, dry weight) and lipid (16% ± 0%, dry weight) were higher in fresh water cultured plants than in sea water cultured plants (12.4% ± 0.5% protein, 3% ± 0% lipid). Fresh water plants contained less sodium (0.25%) and more potassium (3.52%) than sea water plants (4.82% sodium, 1.80% potassium).
Soil Respiration Studies in Tallgrass Prairie in Missouri
Authors: Kucera C. L. , Kirkham Dale R.
Published: May 2006

Rates of carbon dioxide evolution from soil in mid—Missouri tallgrass prairie were highly correlated with temperature of the surface soil. Values increased exponentially with rising temperatures through the seasonal range under observation. Twenty—four—hour measurements employing infrared analysis were conducted periodically during all seasons from August 1968 to June 1970. Weekly averages calculated from regression for the entire year ranged from zero during the coldest period to 450 mg CO_2m(—2)hr(—1) during summer. The annual total was 1,675 g CO_2m(—2). The organic matter equivalent was 1,005 g, approximately 2.2 times the indicated biomass turnover for the root system for the same period. The difference was attributed to root respiration by determining a correlation between CO2 evolution and root biomass with KOH absorption and titration and by converting these data to infrared equivalents. It was estimated that 60% of the total respiration (surface litter excluded) was due to microbial processes in organic turnover and the balance to root metabolism.
Environmental Factors Affecting Seedling Establishment of the Black Mangrove on the Central Texas Coast
Authors: McMillan Calvin
Published: May 2006

The effects of salinity, water turbulence, water depth, and temperature on the establishment of seedlings of black mangrove (Avicennia germinans L.) on the central Texas coast were evaluated in the laboratory. Salinity was not the chief factor limiting seedling establishment, because seedlings rooted in distilled water and in salinities approaching twice the concentration of sea water. Water turbulence, either of distilled or sea water, inhibited root and seedling development. Seedlings tumbled for as much as 12 weeks showed rapid root development when subsequently stabilized. Various water depths promoted extensive root systems, but seedlings did not become established until water depth was reduced to 5 cm or less. High temperature treatment, exposure to 39 degrees —40 degrees C for 48 hr, was lethal to stemless seedlings, but not to seedlings with stems and roots. The results suggest that vivaparous development in this A. germinans population phenologically timed by environmental relations during winter and early spring as a protection against the lethal effects of the high temperatures that prevail on beaches and in shallow water during late spring and summer.
Influences of Light on Activity of Small Mammals
Authors: Kavanau J. Lee
Published: May 2006

The locomotion of eastern chipmunks and least weasels in activity wheels was studied at various illuminance levels on regimes employing both artificial twilights and abrupt changes between day and night light. Several properties of the running of the chipmunks and weasels, and of the white—footed mice of earlier studies, all show the same qualitative dependence on light level. All three animals have a strong tendency to run in only one direction for extended periods of time. They get their directional bearings for this orientation from sightings of nearby objects. The artificial moon is the preferential orientational reference object for mice, whereas other objects in the enclosure seem to be preferred by chipmunks and weasels. The weasels are stimulated to activity by artificial dusks and inhibited by artificial dawn, but not by sudden onset of bright light. The chipmunks are stimulated to activity by artificial dawn. When the length of the daylight period is comparable to that in the wild, they cease activity several hours before dusk. An early "unexpected" dusk or darkness presented while they are active merely slows down their running. These findings and those with white—footed mice suggest the importance of simulating twilights in laboratory investigations of activity and rhythmicity. The fact that the least weasel was 98% nocturnal in light conditions simulating those in the wild suggests that its visual system is evolving from a nocturnal to an arrhythmic type, for this animal is arrhythmic in the field.
Ecology of the Weddell Seal in McMurdo Sound, Antarctica
Authors: Stirling Ian
Published: May 2006

The object of this paper is to discuss the relationship of the Weddell seal (Leptonychotes weddelli) to its habitat, the fast ice of Antarctica. Movements and distribution of Weddell seals during summer are governed by presence of fast ice and availability of breathing and exit holes. It is suggested that this applies during winter also. Local populations are relatively discrete and there is limited emigration and immigration. This is supported by demonstration of significant genetic differences in blood serum transferrins from seals at McMurdo, Mawson, and Wilkes. My data support the hypothesis that the Weddell seal is not migratory but moves as the distribution of breathing holes during winter dictates. Subadults were shown to be distributed further out on the fast ice than adults. Inaccessibility and potential danger involved in reaching this area have resulted in a paucity of sightings of subadults and given rise to the theory that they migrated to the pack ice. The location of pupping colonies is determined by physical factors, mainly glacial movement and tidal action, independent of biological considerations such as exposure or accumulation of drift snow. Adult females show a high degree of fidelity to particular colonies for pupping in successive years. During the pupping season, seals are spaced in the pupping colonies and nonbreeding seals and subadults are excluded from these areas. After weaning of pups, and probably mating of adult females, the mean distance between seals on the sea ice is reduced and subadults are tolerated in these areas by adults. Even so, there is a higher proportion of adults than subadults at new cracks which continually form south of the pupping colonies through the summer. This is probably due to competition for a new food source. The behavior and movements of the Weddell seal in the fast ice of the Antarctic are almost identical to those of its ecological counterpart, the ringed seal (Phoca hispida) in the Arctic and are interesting examples of parallel evolution.
Applying Models Incorporating Age‐Size Structure of a Population to Daphnia
Authors: Sinko James W. , Streifer William
Published: May 2006

Partial differential equations which describe the dynamics of single species populations are applied to Daphnia pulex. Whenever possible, experimental results are used to determine pertinent parameters. Tests are performed to find parameters upon which the model has a critical dependence. The model gives results which are qualitatively in agreement with empirical populations.
An Analysis of Density Effects and Predation in Bufo Americanus Tadpoles
Authors: Brockelman Warren Y.
Published: May 2006

The effects of density on growth and survivorship of Bufo americanus tadpoles and the importance of some predators were investigated experimentally in two small ponds in southeastern Michigan. Tadpoles were raised through metamorphosis at different densities and food levels in screened inclosures placed in the ponds. Most inclosures were open to the natural substratum but others were completely screened to exclude larger predators. In one pond experiment, time of metamorphosis, individual growth variability and mortality were directly related to initial tadpole density, and transformation size was inversely related. The addition of food (natural periphyton on plant litter) produced a density—dependent increase in growth rate. The density—related mortality was correlated with variations in growth rate among pens. Growth rate was correlated with submerged plant cover in the pens. Neither survivorship nor growth was correlated with predator densities. The other pond experiment was characterized by a lack of significant density effects and by high mortality rates. Mortality was correlated with abundance of predators, chiefly nymphs of Odonata and the small leech Batrachobdella picta. Comparison of experimental tadpole densities, growth rates, survivorship and environmental conditions with those of tadpoles in undisturbed environments indicates that the conclusions reached should have relevance to natural population dynamics.
Succession in Algal Mat Communities at Three Different Nutrient Levels
Authors: Wilhm Jerry L. , Long Joseph
Published: May 2006

The effect of three different levels of phosphates and nitrates on temporal variation of structural and functional parameters was studied in algal mat communities in microcosms. The experimental units contained 1 liter of water collected from a farm pond. Microcosms receiving the largest input of nutrients were highest in biomass and pigments, but no greater in net production and respiration than microecosystems receiving an intermediate level of nutrients. These four variables remained low in systems receiving the lowest level of nutrients. The ratio of production to respiration approached unity at all nutrient levels. Production/biomass and production/chlorophyll (i.e., assimilation number) ratios generally decreased with time and leveled off at all nutrient levels. No effects on the pigment diversity ratio, D430/D665 attributable to nutrients were observed.
Carbon Dioxide Exchange Patterns of Cacti from Different Environments
Authors: Patten D. T. , Dinger B. E.
Published: May 2006

The succulent nature of cacti and their acid metabolism create unusual patterns of CO2 exchange. Carbon dioxide exchange rates fluctuate at constant temperatures and maintain near normal patterns under abnormal environmental conditions. The typical pattern (i.e., CO2 release during the day and uptake at night) can be used to determine optimum environmental conditions for maximum net CO2 uptake and therefore net photosynthesis in cacti. Two species of hedgehog cactic from high elevations are shown to differ in internal nighttime temperature requirements for net CO2 uptake, an indication of their adaptation to different environments.
Dependence of Desert Rodents on Winter Annuals and Precipitation
Authors: Beatley Janice C.
Published: May 2006

Winter annual parameters, postreproduction rodent densities, and precipitation, were recorded over 5 consecutive years on 15 sites in Jackass Flats, southern Nevada. When the rain critical to autumn germination came, winter annuals were present during autumn—to—spring, and there was spring reproduction in the rodents (as indicated by summer densities). When the critical rain failed to come, winter annuals populations were negligible and the rodents did not reproduce in the spring. One season, half of the study sites received autumn rainfall adequate for germination, and the other half did not; summer rodent densities increased on the former and markedly decreased on the latter. Following extraordinary heavy early spring rains, following an autumn essentially without rain, there was partially successful germination in early spring, and rodent reproduction occurred in the summer. It is concluded that occurrence and failure of reproduction in desert rodents are correlated with the presence and absence of winter annuals in the environment. The data suggest that dietary water (and vitamins), available in winter annual vegetation prior to or at time of onset of the breeding season, are requirements in the physiology of reproduction of heteromyid species.
Distribution of P^(32) in Ambrosia Artemisiifolia; Its Implication for Trophic Transfer Studies
Authors: Shure Donald J. , Pearson Paul G.
Published: May 2006

Tracer studies on temporal changes in P32 distribution in ragweed. (Ambrosia artemisiifolia) indicated significant differences in P32 activity in different organs. Activity density of flower tissue was significantly greater than of other organs throughout the study. Differences between root, stem and leaf activities were only present early in the experiment when activity densities of all organs were at their highest. The total isotope pool was originally greatest in leaf tissue, being surpassed by flower tissue during the latter part of the experiment. The differences in activity density levels indicate variable amounts of P32 available to consumers which feed at different sites on ragweed. Leaf, flower, or whole plant activity density give quite different results in estimates of trophic transfer indices for two consumer species. Use of activity density measures from the actual site at which a consumer feeds is recommended for a more accurate estimation of trophic transfer.
An Inexpensive Pressure Chamber for Xylem Water Tension Measurements
Authors: Toriessen Peter
Published: May 2006

An inexpensive, easily constructed pressure chamber is described which can be used for estimating xylem water tension. Such a chamber apparatus can be assembled for as little as $60 and can measure tensions greater than–100 bars. The static testing of the finished chamber with either water or oil is necessary before it can be used.
Yello Skunk‐Cabbage (Lysichitum Americanum Hult & St. John)‐‐An Indicator of Water‐Table Depth
Authors: Minore Don
Published: May 2006

Water—table depths and vegetation were measured on 11 lowland areas near the Oregon cost. The density and petiole length of yellow skunk—cabbage (Lysichitum americanum Hult & St. John) were correlated with average winter water—table depths wherever winter water tables were below the soil surface (r = —0.90). Slough sedge (Carex obnupta Bail.) grew with the skunk—cabbage wherever average winter water tables were above the soil surface.
Influence of Temperature and Humidity on Distribution of Lichens in a Minnesota Bog
Authors: Pearson L. C.
Published: May 2006

Near the open center of the bog, where light intensity was higher and average relative humidity lower than in the neighboring woods, lichen cover on the bark of trees was significantly higher (over 50° of bark covered) than in the woods. Lichens were still abundant in the crowns of the trees, although considerably reduced on the bark of trees in the woods. Over 20 kinds of lichens were observed, but Parmeilia caperata, Evernia mesomorpha, and P. sulcata made up 98% of the lichen cover on the trunks of the trees. Most lichens favored the lower and more variable humidity which prevailed at 80—160 cm above the ground. Parmelia caperata, Evernia mesomorpha, P. subrudecta, and Usnea comosa appear to be good indicators of moisture conditions, while P. caperata, P. sulcata, P. physodes, and some crustose lichens are indicators of temperature and light. Lichen distribution suggests that variation of environmental conditions, especially moisture, is of greater significance than maintenance of so—called optimum conditions. Lichen cover and microtopography were positively associated, and lichens may be regarded as good indicators of microclimatic conditions.
Some Aspects of the Water Economies of Nine Species of Amphibians
Authors: Schmid William D.
Published: May 2006

The water economies of nine species of anuran amphibians have been examined for (1) response to controlled desiccation, (2) response to prolonged hydration, and (3) some physiological factors related to the observed interspecific differences in these responses. The nine species exhibited a marked variation in habitat preferences with regard to the availability of water, and correlations were observed between habitats and responses to experimental conditions. Species from more aquatic habitats exhibited lower tolerances to desiccation; however, they were able to endure hydration for significantly longer periods than terrestrial species. Physiological specialization was observed which may be primarily responsible for the observed interspecific differences in response to prolonged hydration. The skin of aquatic species was less permeable to water and the effective osmolarity of blood plasma was less than that of terrestrial species. It has been suggested that species from terrestrial habitats, especially those of the families Bufonidae and Hylidae, may be limited from wintering in water because of their intolerance to hydration.
An Area of Pristine Vegetation in Craters of the Moon National Monument, Idaho
Authors: Tisdale E. W. , Hironaka M. , Fosberg M. A.
Published: May 2006

A 180—acre kipuka near Carey, Idaho, surrounded by rough lava areas has apparently never been grazed. The entire kipuka is covered by the sagebrush—grass types of which three communities have been recognized and described: the Artemisia tripartita/Festuca idahoensis, the A. tridentata/Festuca idahoensis/Agropyron spicatum, and the A. longiloba/Festuca idahoensis/Stipa thurberiana communities. Chestnut soils of the kipuka developed on loess show considerable influence of the residual basalt, and differences in aspect and depth are closely associated with the occurrence of the three plant communities. The kipuka is now protected and is being used for studies of sagebrush—grass ecosystems. Fluctuation in the relatively stabilized vegetation is evident with recent deterioration of Festuca and its replacement by Bromus tectorum, presumably a result of drought.
Escape of Algae from Frozen Lakes and Ponds
Authors: Wilson A. T.
Published: May 2006

Pieces of algal mats are pulled from bottoms of shallow ponds in Antarctica by melting ice in spring. Heat absorbed from the sun by the mats causes the mats to melt the overlying ice and they move to the surface. Once on the surface they dry and are blown away.
Ranges of Temperature Tolerance For Germination of Mimulus Seeds From Diverse Populations
Authors: Vickery Robert K.
Published: May 2006

The germination temperature tolerance ranges of 12 Mimulus populations representative of the morphological, geographical, and ecological diversity of section Simiolus were investigated. The seeds of each population were tested in a series of 27 artificial climates formed from various combinations of temperatures ranging from —7° to +50°C. All populations exhibited relatively high and rapid germination in a central core of moderate temperatures. The populations differed greatly, however, in the extent of the temperature ranges in which germination could occur, even slowly and in low yield. Differences may be due to differences in environmental stress or to quantitative genetic changes resulting from mutations to aneuploidy and polyploidy. Closeness of genetic relationship of the populations tended to be reflected in similarities of germination temperature tolerance ranges.
Species Diversity in Chydorid (Cladocera) Communities
Authors: Whiteside Melbourne C. , Harmsworth Rodney V.
Published: May 2006

Microfossil remains from surficial sediments of 20 Danish and 14 northern Indiana Jakes were counted, and their relative percentages calculated. Using the function H = — Σp°ilog2°° species diversity was calculated for each lake. Indices of diversity for each lake and data on primary production and transparency were subsequently ranked and Spearman's rank correlation coefficient was determined between species diversity and production, and species diversity and transparency. Interpretation of results within the framework of information theory was not satisfactory. It is sugested that species diversity of chydorids is controlled primarily by complexity of the thier habitat, the rooted aquatic macrophytes of lakes.
Spatio‐Temporal Relationships of Nuthatches and Woodpeckers in Ponderosa Pine Forests of Colorado
Authors: Stallcup Patrick L.
Published: May 2006

Interspecific segregation of foraging activities of nuthatches and woodpeckers was investigated from June 1964 to June 1966 in a stand of ponderosa pine. The composition and density of populations were assessed throughout the year. Location of foraging activities was quantified by measuring the length of time each species occurred in specified zones of the environment. Interspecific differences of zonation were statistically analyzed for the reproductive and non—reproductive seasons separately. White—breasted and Pigmy Nuthatches and Hairy Woodpeckers nested in the area and were sympatric throughout the year. Red—shafted Flickers and Williamson's Sapsuckers nested in the area but were sympatric with the 2 nuthatches and Hairy Woodpecker only during the reproductive season. Red—breasted Nuthatches nested at higher elevations and were sympatric with the Hairy Woodpecker and other nuthatches only during the non—reproductive season. Pigmy Nuthatches foraged most extensively in the foilage of live pine in both seasons. White—breasted Nuthatches concentrated their foraging activities on the trunks and large branches of pine. Zones used most extensively by all nuthatches were mutually exclusive in both seasons. Zones of Hairy Woodpeckers and Williamson's Sapsuckers overlapped considerably in the reproductive season. Hairy Woodpeckers foraged for arthropods on the surface of trunks and branches of living trees but more extensively for subcortical arthropods of dead trees, stumps and logs. Williamson's Sapsuckers foraged almost exclusively for ants on trunks of living pines. In the non—reproductive season, Hairy Woodpeckers foraged most extensively for seeds of pine cones. Williamson's Sapsuckers foraged almost exclusively on phloem of trunks of living pines. Foraging activities of Red—shafted Flickers were confined to the ground and thus segregated from the major foraging zones of all other birds. Nuthatches and woodpeckers were shown to be segregated by spatial and behavioral differences of foraging activities and by temporal differences of their residential status. It is concluded that climate, available space and competition for food were important in the evolutionary development of these interspecific differences.
Mortality and Stability in a Low Diversity Subtropical Intertidal Community
Authors: Green Roger H.
Published: May 2006

The Crib Island, Queensland, intertidal community is dominated by three species: the filter—feeding mactrid bivalve Notospisula parva Petit, and the naticid gastropods Polinices sordidus Swainson and Polinices conicus Lamarck. Empty drilled shells suggest naticid predation as a source of mortality for all three species. Field sampling and laboratory experiments indicate that, of a total N. parva mortality of 46% during the year December 1965 to December 1966, only 4% per year was caused by naticid predation. A mortality of 28% was caused by shell—destroying predators such as skates. Interaction between high densities and rapid seasonal growth is suggested as an important source of density dependent mortality. The naticids are probably regulated by the density of their prey (N. parva), and compensate for fluctuating N. parva abundance by breeding year—round and preying on smaller individuals of their own genus.
Ecology of Picea Chihuahuana Martinez
Authors: Gordon Alan G.
Published: May 2006

Picea chihuahuana probably arrived in North America during Cretaceous or earlier times. The Physiography, climate, and forest geography of its present range in the Sierra Madre Occidental of Mexico are described. The forests are cool montane temperate rather than boreal. In the station examined. P. chihuahuana was distributed only on fresh and moist sites. Growth rates both in height and diameter on moist sites exceeded those on the fresh. The culmination point for diameter growth was at 85 years. The mean specific gravity was .347, and differences due to site were not significant. The moist site soils supporting P. chihuahuana differed from the fresh site soils only in having flower pH, Ca, and K levels. Since the sites were closely associated and the parent materials identical, it is assumed that these differences were due to differences in moisture regime. The foliar nutrient concentration of N, P, and K decreased with increasing needle age except that P and K increased markedly in the oldest needles. Conversely, Ca increased with advancing needle age but decreased in the oldest needles. P. chihuahuana shows a remarkable tolerance for high Ca concentration. The associated vegetation of the P. chihuahuana stand was measured on both fresh and moist sites, and significant differences between the plant assemblages of these sites were found. Its present range and pattern of regeneration indicate that P. chihuahuana may not long escape extinction.
Ecology of Dodecatheon Meadia L. (Primulaceae) in Tennessee Glades and Woodland
Authors: Turner Barbara Holman , Quarterman Elsie
Published: May 2006

Two populations of Dodecatheon meadia var. meadia L., one each in a woodland and a cedar glade habitat, were compared with respect to phenology and seed germination requirements. Differences between the two populations are earlier shoot appearance and flowering in woodland plants; longer persistence of capsules and greater total seed set in glade plants; greater tolerance of temperature extremes in glade plants; and stable size and density of the glade populations. Germination of woodland seeds was influenced by temperature, while length of cold pretreatment influenced rate and percentage of germination of glade seeds more than temperature. No correlation could be established between germination percentages and age of seeds. The two populations are interfertile, at least when glade plants furnish the pollen.
Caloric Values of Seeds From Four Range Sites in Northeastern Kansas
Authors: Johnson Stephen R. , Robel Robert J.
Published: May 2006

Important in the bioenergetics of granivores is the difference in energy content of seeds from plants grown on different areas within the organism's normal environment. To determine possible differences in energy content, seeds of nine species of plants (Solanum rostratum, Helianthus annuus, Rhus aromatica, R. glabra, Ambrosia trifida, Cornus drummondi, Symphoricarpos orbiculatus, Setaria lutescens, and Bromus japonicus) were collected from four distinct range sites. No differences were detected (except for Rhus aromatica) between mean energy content of seeds from the four sites. However, significant intraspecific differences (P < 0.05) were noted between means of energy content of seeds from different locations within the same range site.
Winter Diet of the Peruvian Desert Fox
Authors: Huey Raymond B.
Published: May 2006

The winter food habits of the native desert fox of northwestern Peru were examined by an analysis of fecal pellets collected in two areas. In the Sechura Desert, foxes eat mainly the seed pods of perennial shrubs. In a coastal area, the foxes supplement their largely herbivorous diet with carrion and crustaceans.
Population Control in Arctic Ground Squirrels
Authors: Carl Ernest A.
Published: May 2006

Unlike most tundra rodents, the arctic ground squirrel, Spermophilus undulatus, maintains a relatively constant population. The squirrels exist in two types of groupings: (1) breeding colonies, which cannot expand because their members are territorial, the females reacting to the availability of burrow sites (an environmental constant), and (2) refugee populations, which cannot expand because they cannot breed and, living in habitat only periodically suitable for squirrels, are killed off twice each year. The breeding populations have two distinct types of territories: breeding territories from May to August and prehibernation territories from August to November. During each episode, surplus animals are driven from the colonies and enter the refugee populations, where they are subjected to heavy predation by foxes and bears.
The Ingestion Rates of Microarthropods in Pine Mor, Estimated with Radioactive Calcium
Authors: Kowal N. E. , Crossley D. A.
Published: May 2006

Ingestion rates, as influences by temperature, of the four layers of mor (L, F_1, F_2, H) by saprovores, and of saprovores by predators, were estimated in microcosm studies. Taxa used were Symphypleona, Poduromorpha, Entomobryomorpha, total Collembola, mature Oribatei, immature Oribatei, total Oribatei, total saprovores, and total predators. Several linear differential equations were used as models, in which the elimination rates were either held constant or temperature—and—body—sized—adjusted. Estimated ingestion rates for total saprovores, with temperature—and—body—sized—adjusted elimination rates, were 0.009. 0.022, 0.052, and 0.046 day(—1) at 6 degrees, 15 degrees, 25 degrees, and field temperatures, respectively, with 41%, 39%, 17%, and 3% of their food supply coming from the L, F_1, F_2, and H layers, respectively. Estimated ingestion rates for total predators, using one of two models and with temperature—and—body—sized—adjusted elimination rates, were 0.018, 0.023, 0.033, and 0.020 day(—1) at 6 degrees, 15 degrees, 25 degrees, and field temperatures, respectively.
Adaptation of Growth Form in Echium Leucophaeum (Boraginaceae)
Authors: Lems Kornelius , Holzapfel Christina M.
Published: May 2006

Ecotype formation in eight populations of Echium leucophaeum was studied on La Palma (Canary Islands) at 100—m intervals from sea level to 600 m elevation. Climate varied with altitude, the lower elevation having higher temperatures, evaporation, and wind velocity and lower rainfall. A method for recording growth form of individual plants was developed whereby lateral branch production and branching patterns of woody plants could readily be determined. Height growth, lateral branch production, periodicity, and number of branching cycles of Echium were all found to be significantly different in the field, plants from higher elevations having longer branches, more laterals per cycle, fewer cycles, and retarded flowering and fruiting compared with plants near sea level. Two generations of seedlings of the extreme types grown in transplant gardens showed significant differences in inherent rate of growth, indicating genetic adaptation of high and low altitude ecotypes. No significant differences could be shown in the rate of lateral branch formation and periodicity; differences observed in the field with respect to these characteristics may be physiological responses.
Age of Mature Pine (Pinus Taeda) Stand in South Carolina
Authors: Stalter Richard
Published: May 2006

A mature stand of Pinus taeda in the Congaree Swamp was sampled with twenty 10— by 10—m quadrats for trees and 20 smaller quadrats for saplings and seedlings. Annual ring counts indicated that most trees are 100—175 years old. Lack of pine reproduction and copious development of hardwoods suggest that this pine sere has nearly reached its culmination, but has existed much longer than P. taeda seres elsewhere.
Evidence for Error in Pressure‐Bomb Estimates of Stem Xylem Potentials
Authors: Ritchie Gary A. , Hinckley Thomas M.
Published: May 2006

The hydrostatic component of water potential was measured concurrently in stems and needles of five species of conifers (Pinus contorta, P. jeffreyi, Pseudotsuga menziesii, Abies amabilis, and A. procera). In Douglas—fir and the true firs pressure—chamber measurements of potentials were up to 4 bars more negative in stems than in needles. The difference appears to be due to filling of non—vascular xylem tissue with fluid during measurement. This tissue seems to function as a water reservoir, enabling needles to maintain relatively high turgor levels during periods of rapid transpiration.
Peptide mimetic NC114 induces growth arrest by preventing PKCδ activation and FOXM1 nuclear translocation in colorectal cancer cells
Authors: Taguchi Yuki , Nakaya Takeo , Aizawa Kenichi , Noguchi Yoshiyuki , Maiya Nobuhiko , Iwamoto Chisako , Ohba Kenichi , Sugawara Minoru , Murata Masayuki , Nagai Ryozo , Kano Fumi
Published: March 2024

The peptide mimetic, NC114, is a promising anticancer compound that specifically kills colorectal cancer cells without affecting normal colon epithelial cells. In our previous study, we observed that NC114 inhibited the Wnt/β‐catenin pathway, with significant downregulation of both Ser 675‐phosphorylated β‐catenin and its target genes, cyclin D1 and survivin. However, the molecular mechanism responsible for its cytotoxic effect has not yet been fully characterized. In the present study, we demonstrated that NC114 prevented cell cycle progression from S to G2/M phase by downregulating cell cycle‐related gene expression, and also induced growth arrest in SW480 and HCT‐116 colorectal cancer cells. A novel covariation network analysis combined with transcriptome analysis revealed a series of signaling cascades affected by NC114 treatment, and identified protein kinase C‐δ (PKCδ) and forkhead box protein M1 (FOXM1) as important regulatory factors for NC114‐induced growth arrest. NC114 treatment inhibits the activation of PKCδ and its kinase activity, which suppresses MEK/ERK signaling. Attenuated MEK/ERK signaling then results in a reduction in FOXM1 phosphorylation and subsequent nuclear translocation of FOXM1 and β‐catenin. Consequently, formation of a T‐cell factor‐4 (TCF4)/β‐catenin transcription complex in the nucleus is inhibited and transcription of its target genes, such as cell cycle‐related genes, is downregulated. The efficacy of NC114 on tumor growth was confirmed in a xenograft model. Collectively, elucidation of the mechanism by which NC114 induces growth arrest in colorectal cancer cells should provide a novel therapeutic strategy for colorectal cancer treatment.
CDC: Dramatic increase in OD deaths from smoking opioids/stimulants
Authors: Knopf Alison
Published: March 2024

In a Morbidity and Mortality Weekly Report (MMWR) released last week, the federal Centers for Disease Control and Prevention (CDC) reported that overdose (OD) deaths from smoking illegally manufactured fentanyls and fentanyl analogs have increased dramatically, from 13.3% to 232.1% from 2020 to 2022. The study, “Routes of drug use among drug overdose deaths — United States, 2020‐2022” is by Lauren J. Tanz, ScD, and colleagues at the CDC and the Oak Ridge Institute for Science and Education.
High MME use by mother linked to increase in preterm births
Authors: Knopf Alison
Published: March 2024

Women who use prescription opioids for pain during pregnancy are more likely to deliver their babies prematurely, a study by Sarah S. Osmundson, M.D., and colleagues at Vanderbilt University has found. The study, “Prescription Opioid Exposure During Pregnancy and Risk of Spontaneous Preterm Delivery,” was published Feb. 5 in JAMA Network Open.
Strategies for Improving Efficiency and Stability of Inverted Perovskite Solar Cells
Authors: Zhang Wenxiao , Guo Xuemin , Cui Zhengbo , Yuan Haobo , Li Yunfei , Li Wen , Li Xiaodong , Fang Junfeng
Published: March 2024

Perovskite solar cells (PSCs) have attracted widespread research and commercialization attention because of their high power conversion efficiency (PCE) and low fabrication cost. The long‐term stability of PSCs should satisfy industrial requirements for photovoltaic devices. Inverted PSCs with a p‐i‐n architecture exhibit considerable advantages because of their excellent stability and competitive efficiency. The continuously broken‐through PCE of inverted PSCs shows huge application potential. This review summarizes the developments and outlines the characteristics of inverted PSCs including charge transport layers (CTLs), perovskite compositions, and interfacial regulation strategies. The latest effective CTLs, interfacial modification, and stability promotion strategies especially under light, thermal, and bias conditions are emphatically analyzed. Furthermore, the applications of the inverted structure in high‐efficiency and stable tandem, flexible photovoltaic devices, and modules and their main obstacles are systematically introduced. Finally, the remaining challenges faced by inverted devices are discussed, and several directions for advancing inverted PSCs are proposed according to their development status and industrialization requirements.
A Solely Fe‐Catalyzed Sonogashira‐Type Coupling of non‐Activated Secondary Alkyl Iodides with Terminal Alkynes
Authors: Zhurkin Fedor , Parisot William , Lefèvre Guillaume
Published: March 2024

An iron‐catalyzed Sonogashira coupling of non‐activated secondary alkyl iodides with terminal alkynes is described. The reaction proceeds under mild conditions in N‐MethylPyrrolidone without auxiliary ligand or co‐catalyst. This procedure allowed the obtention of 28 coupling products. Moreover, slow addition of LiHMDS base allows to achieve up to 89% yields. This method enables the conversion of non‐activated alkyl iodides in a Fe‐catalyzed Sonogashira‐type cross‐coupling, which was so far not achievable with iron catalysts. Preliminary mechanistic studies suggest the implication of a key single electron transfer in the catalytic process.