bluuebunny/crossref_metadata_2025 huggingface dataset:
Eisenstein's Later Work at the Proletkult
Authors: Gordon Mel
Published: April 2006

In September 1923, four months after the premiere of his provocative circus production of The Wiseman and three years before his recognition as Europe's foremost filmmaker, Sergei Eisenstein collaborated with the writer and linguist Sergei Tretyakov in the preparation of two new revolutionary plays, Do You Hear, Moscow?! and Gas Masks. More than Nikolai Foregger and Meyerhold, more than all of his teachers, the twenty-five-year-old Eisenstein was now considered by many as the most radical director in a theatre-mad Moscow. His manifesto “Montage of Attractions” [LEF #1 May 1923] and extreme reworking of Alexander Ostrovsky's nineteenth-century comedy, Enough Stupidity in Every Wiseman set theatrical circles on edge. [See T61 for a translation of the essay and a description of this production.] The young proponents of left-wing culture, centered around the poet Mayakovsky and the periodical LEF, hailed Eisenstein as the next intellectual/artistic savior.
Atelier Théâtre et Musique
Authors: Shank Theodore
Published: April 2006

The French theatre group ATEM (Atelier Théâtre et Musique) was formed by composer Georges Aperghis in the fall of 1975 to begin explorations that would lead to a series of productions in which commonplace gestures and sounds are scored according to musical principles. The group has developed what Aperghis calls a “grammar” consisting of “systems” that provide a means of structuring fragments of everyday life, setting them off in such a way that the spectator perceives them afresh rather than ignoring them as commonplace.

Five actor-musicians, together with Aperghis, comprise the entire group, taking on all of the research, administrative, technical, and performance responsibilities. They are subsidized in part by the city of Bagnolet, a bedroom suburb of Paris with a population of 36,000, and have attempted to relate their work to everyday life in the community.
Energy Allocation in the Allegheny Mountain Salamander, Desmognathus Ochrophaeus
Authors: Fitzpatrick Lloyd C.
Published: April 2006

The reproductive cycle, energy budget, and relationships between rates and energetics of vitellogenesis, lipid deposition and depletion, and changes in lean carcass tissue were examined in Desmognathus ochrophaeus salamanders from northeastern Ohio. Oviposition begins prior to emergence in mid—April, reaches a peak in mid—May, and continues in greatly reduced frequency into September. Lipids in the carcass and ovarian fat bodies apparently are used for maintenance and vitellogenesis during winter dormancy (mid—October to mid—April) and after emergence in the spring when food reserves are scarce. Carcass lipids, lean carcass tissue, and perhaps fat body lipids are used for maintenance during brooding. A typical female oviposits in mid—May, replaces depleted lipids and lean carcass tissue by late August, and produces intermediate—sized follicles before winter and full—sized follicles during April and early May. Energy ingested, egested, assimilated, and lost through respiration was examined in gravid females, spent females, and males acclimated to four temperature—photoperiod regimes: (1) 5°C, LD 10:14; (2) 5°C, LD 14:10; (3) 15°C, LD 10:14; and (4) 15°C, LD 14:10. Size, sex, reproductive condition, and temperature significantly influence energetics in D. ochrophaeus. Photoperiod does not affect metabolism significantly at either temperature. There is an inverse exponential relationship between body weight and weight—specific rates of ingestion, egestion, assimilation, and respiration. Gravid females, actively depositing yolk in follicles, show higher O2 consumption rates than recently spent females and males at 15°C, but not at 5°C when yolking rates apparently are reduced. Rates of O2 consumption are significantly higher at 15°C than 5°C. At 15°C gravid females, spent females, and males lost 43.2, 3.60, and 3.84 cal g—1 day—1 metabolic heat; at 5°C they lost 1.92, 1.92, and 1.68 cal g—1 day—1, respectively. Salamanders cease to feed at 5°C. At 15°C gravid females, spent females, and males ingested 21.0, 37.8, and 23.8 cal g—1 day—1 and egested 2.7, 5.1, and 2.9 cal g—1 day—1, with assimilation efficiencies of 87.2%, 86.3%, and 88.2%, respectively. The estimated annual energetics of a typical female are: ingestion = 2,940 cal; egestion = 378; assimilation = 2,562; respiration = 1,104.4; and secondary production = 1,457.6. Reproductive activities (vitellogenesis = 807.5 and brooding maintenance = 430 cal) cost 48.3% of a female's annual energy flow (A = 2,562 cal).
Late Pleistocene Palynology and Biogeography of the Western Missouri Ozarks
Authors: King James E.
Published: April 2006

Palynological investigations of spring deposits were conducted as part of an interdisciplinary research effort into late Pleistocene archaeology, geology, and paleoecology of the western Missouri Ozarks. The springs, located in the Pomme de Terre River valley in Benton and Hickory Counties, Missouri, lie 400 km south of the maximum extent of the Wisconsin ice sheet on the present Great Plains—Eastern Deciduous Forest border. The valley will soon be flooded by a government impoundment. Two springs were completely excavated and three others sampled, including a spring originally excavated by Albert Koch in 1840. The pollen record, with associated plant macrofossils, is divided into three distinct zones: a lower nonarboreal pollen (NAP) and pine zone, a middle spruce— (Picea) dominated zone, and an upper zone of spruce with deciduous elements. Radiocarbon dates show that the NAP—pine zone was established prior to 40,000 BP and existed until 20,000—25,000 BP; it was deposited during the mid—Wisconsin interstade. The mid—Wisconsin interstadial vegetation of the Ozarks is interpreted as an open pine—parkland. Plant macrofossils of Pinus banksiana in this zone indicate that jack pine was present. Spruce was probably absent as no spruce macrofossils and only traces of spruce pollen were found. The associated mid—Wisconsin fauna is dominated by mastodon (Mammut americanum) with horse (Equus) and musk—ox (Symbos). With the onset of late Wisconsin full—glacial conditions, variously dated at 20,000—25,000 BP, pollen dominance shifts from NAP—pine to spruce. This is interpreted as the replacement of the pine—parkland by boreal spruce forest. Two pollen zones are apparent within the full—glacial: an older zone with up to 92% spruce pollen occurring after the transition from NAP—pine to spruce, and a younger zone with less spruce (38%) and more thermophilous deciduous tree pollen. The change to less spruce and more deciduous tree pollen apparently reflects slightly improved climatic conditions during a late phase of the full—glacial; the zone is radiocarbon dated at 16,500 BP on spruce logs. It contains abundant spruce and larch (Larix) macrofossils associated with the remains of at least 30 mastodons plus giant beaver (Castoroides), ground sloth (Paramylodon), tapir (Tapirus), deer (Odocoileus), and horse (Equus). The western Missouri Ozarks were covered by open pine—parkland from at least 40,000 BP until the start of the full—glacial 20,000—25,000 BP, then boreal spruce forest until at least 13,500 BP. Deciduous elements became more prominent in the spruce forest in its latter phase. The present oak—hickory forest developed after the decline of the spruce and is thus no older than postglacial.
The Breeding Migrations and Interhabitat Wandering of the Vermilion‐Spotted Newt Notophthalmus viridescens (Rafinesque)
Authors: Hurlbert Stuart H.
Published: April 2006

The breeding migrations and wandering movements of Notophthalmus viridescens were monitored at several ponds in Dryden, Tompkins County, New York. Breeding migrations occurred in both the spring (April—May) and fall (August—October, November, or December) to all permanent ponds. The spring migrations involved both eft migrants and adult migrants, their relative numbers varying considerably from pond to pond. The fall migrations involved eft migrants almost exclusively. Eft migrants were maturing juveniles returning to the water for the first time; adult migrants were individuals which had bred before and subsequently spent some time, often an entire winter, on land. The sex ratio of eft migrants was 42 to 47% males, that of aquatic adults at least 55% males; male eft migrants had a greater future life expectancy than do female eft migrants. Male migrants arrived earlier in the spring, female migrants arrived earlier in the fall. Breeding migrants tended to use linear depressions (e.g. streambeds, slope junctions) as migration routes; their routes were conspicuously altered by seasonal changed in vegetation. About 57% of N. viridescens migrants, but only 3% of Ambystoma maculatum migrants, reached the ponds during the day; the remainder entered at night. Breeding migrations were more strongly correlated with rainfall and temperature in early spring than in late spring and in late fall than in early fall. For a brief period following their arrival at a pond migrants wandered back and forth between water and land, especially during rainy weather. Fully aquatic adults abandoned temporary ponds as or after these dried up. In July, August, and September some adults left permanent ponds, especially during rainy weather.
Edaphic Climax Pattern of the Pygmy Forest Region of California
Authors: Westman Walter E.
Published: April 2006

The dwarfed conifer forests occurring on the coastal terraces of Mendocino County, California, are oligotrophic communities containing edaphic endemics as dominants. Species distributions and community characteristics are traced along a gradient in podzolization of the soils from these pygmy conifer stands on highly weathered terrace spodosols, to redwood stands on weakly developed slope spodsols. Vegetation stature, canopy closure, species richness, litter biomass and pH generally decrease along the gradient as podzolization and nutrient impoverishment increase, whereas soil organic matter and available water capacity tend to be highest at the gradient extremes. Analyses of pygmy forest soils show low levels of macro— and micro—nutrients, and high levels of exchangeable aluminum. When ordinations of stands based on vegetational data are compared with rankings based on environmental data, changes in pH of the soil A horizon are found to correlate most highly with vegetation changes. Nutrient loss and acidification, initiated by varying rates of soil weathering in the pygmy forest region, may be aggravated, in the case of pygmy forest soils, by a series of feedback effects, including solubilization of possibly toxic amounts of aluminum by low pH, which may contribute to the observed plant stunting and shrinking pools of nutrients in the biomass. A ranking of stands along a soil nutrient gradient, based on field observations and presence data for species, correlated successively less strongly with ordinations computed by similarity—projection, Bray—Curtis method, importance—projection, principal components analysis, and factor analysis. Although these ordinations were expected to produce distortions in the interstand relations due to the modal and even polymodal nature of species response curves and to the presence of species not spanning the range of the data set, additional distortions due to variability in sample data were also highlighted.
Genetic, Behavioral, and Reproductive Attributes of Dispersing Field Voles Microtus pennsylvanicus and Microtus ochrogaster
Authors: Myers Judith H. , Krebs Charles J.
Published: April 2006

To investigate experimentally the relationship between dispersal and population regulation in small mammals, voles were removed continuously from two plots in southern Indiana for 2 years. Three control populations of two Microtus species were monitored over the same period, and animals dispersing onto the experimental areas were compared with resident control animals for the following characteristics: (1) age, weight, and sex; (2) genotype for two polymorphic plasma proteins, leucine aminopeptidase (LAP) and transferrin (Tf); and (3) exploratory, aggressive, and general activity behavior of males. Dispersal was most common during the fall and winter, and in the phase of population increase 59% of male and 69% of female Microtus pennsylvanicus loss from two control populations could be accounted for by dispersal. In contrast, little of the high loss during the population decline could be associated with dispersal. In the late peak and decline periods male M. pennsylvanicus of the Tf—E and LAP—S phenotypes were more common among dispersing animals. In Microtus ochrogaster males the very rare Tf—F type was found only in dispersing ales. Young females were more common in dispersing populations of both species, and sexual maturation and dispersal were related in both vole species. However, dispersal by adults was only common. Dispersing males tended to be less active than males of resident populations. During a period of peak population density, dispersing male M. pennsylvanicus were more aggressive. As population density increased, "intolerant" animals moved into less densely populated areas. The genetic differences between dispersing and resident populations tend to support Howard's hypothesis that a genetic polymorphism influences the tendency to disperse. The association between increasing populations and abundant dispersal agrees with Lidicker's theory of population regulation by emigration and Chitty's hypothesis that a behavioral polymorphism regulates population density.
Late Quaternary Vegetation History of the Eastern Highland Rim and Adjacent Cumberland Plateau of Tennessee
Authors: Delcourt Hazel R.
Published: April 2006

Vegetation change during the past 25 000 years in and near the present Mixed Mesophytic Forest Region is inferred from pollen and plant macrofossil analyses of sediment cores from two sites on the eastern Highland Rim of Middle Tennessee, USA. Anderson Pond, in White County, dates from 25 000 radiocarbon years BP to present. During the Farmdalian Interstadial, 25 000 yr BP, northern Diploxylon pines, spruce, and deciduous trees were present at Anderson Pond, indicating a cool, moist climate. From 19 000 to 16 300 yr BP, during the Late Wisconsin glacial maximum, boreal taxa of jack pine, spruce, and fir were dominant. Late—glacial climatic amelioration began in Middle Tennessee at about 16 300 yr BP, with replacement of jack pine—spruce—fir forest by deciduous forest. Ash, ironwood, hickory, birch, butternut, willow, and elm increased in importance first, followed by beech and sugar maple. Mixed mesophytic forest taxa were most abundant during the early Holocene, between 12 500 and 8000 yr BP. A warming and drying trend between 8000 and 5000 yr BP is reflected by high influx values for pollen of oak, ash, hickory, swamp alder, and buttonbush, and by diminishing importance of mixed mesophytic forest taxa. Mingo Pond, Franklin County, Tennessee, contains a pollen record estimated to extend back to 14 000 yr BP. Mixed mesophytic forest taxa were abundantly represented at Mingo Pond during the late glacial and early Holocene, along with pollen representing prairie vegetation. Oak and sweetgum dominated the mid— and late Holocene record from Mingo Pond. Stratigraphic sites from the Missouri Ozarks to the Atlantic Coastal Plain date the full glacial in the southeastern United States between 23 000 and 16 500 yr BP. During the glacial maximum, boreal—like coniferous forests of spruce, jack pine, and fir extended southward to 34°N latitude. Mesic deciduous forest persisted through the full glacial at 35°N at Nonconnah Creek near Memphis. Full—glacial refuges for deciduous forest species may have also existed in south—facing gorges of the Cumberland Plateau and southern Appalachian Mountains in addition to bluffs along major streams in the southeastern United States. During the late glacial, beginning about 16 500 yr BP, boreal—like coniferous forest was replaced in midlatitudes (34° to 37°N) by cool—temperate coniferous—deciduous forest. In the early Holocene, between 12 500 and 8000 yr BP, cool—temperate mixed mesophytic forest prevailed between 34° and 37°N. The Mixed Mesophytic Forest Region assumed its present distribution in the mid—Holocene.
Nutrient Transport in Surface Runoff from a Subalpine Watershed, Lake Tahoe Basin, California
Authors: Leonard Robert L. , Kaplan Louis A. , Elder John F. , Coats Robert N. , Goldman Charles R.
Published: April 2006

The watershed of Ward Creek, a tributary to oligotrophic Lake Tahoe in the Sierra Nevada, has been investigated since 1971 with the objective of improving our knowledge of processes of nutrient and sediment release and transport to the lake. Quantitative data on selected stream water parameters were collected for 3 yr (1972—1975) at three stations on Ward Creek, two on the main upper tributaries and one near the stream mouth. Comparative data were collected at a stream mouth station on adjacent Blackwood Creek in the 3rd yr. The parameters were selected on the basis of their significance to eutrophication of Lake Tahoe. Precipitation in a normal year is over 90% snow but annual patterns vary widely and rainfall at any time of year can be highly important in sediment and nutrient transport. Water discharge and the flux of suspended sediments, NO3—N, phosphorus, iron and trace metals were dominated by the spring snowmelt runoff from mid—April to mid—June. However, in 1974 heavy fall and summer rains accounted for a large percentage of the annual flux of sediments and nutrients in a total of only 14 d. The spring runoff was characterized by distinct diel water discharge patterns. Similar but not coincident patterns were found to exist for sediments and nutrients, including NO3—N, but not for soluble phosphorus. The Ward watershed has 87% the area of Blackwood but discharge proportionately much lower quantities of sediment and nutrients in comparable water yields per hectare in water year 1975. This contrast in fluxes was probably accounted for in the history of greater disturbance by man in Blackwood Canyon. The principal source of suspended sediments in Ward Creek was streambank erosion in the lower reaches of the channel. The dominant form of inorganic nitrogen in Ward was NO3—N derived from precipitation, symbiotic nitrogen fixation and nitrification of organic nitrogen in forest soil. Phosphorus and iron were almost entirely in particulate form and thus their periods of flux occurred during high flows and sediment transport. Sediment and nutrient loading of Lake Tahoe from the Ward and Blackwood watersheds reflects a history of soil disturbance and vegetation removal. Logging, fire and stream channel diversion have been the dominant perturbations. Conservative extrapolation of annual loading data from this study to the entire basin indicates that algal nutrient levels in the lake probably have increased sufficiently in the century of man's intensive disturbance of the basin watersheds to account for increased phytoplankton and periphyton production that have been measured and observed since 1958.
Late‐Wisconsinan Vegetational History at Wolf Creek, Central Minnesota
Authors: Birks H. J. B.
Published: April 2006

The pollen and plant—macrofossil stratigraphy of Wolf Creek, an extensive marsh within one of the oldest drumlin fields in central Minnesota, is described for the period 20,500 to 9150 yr ago. The pollen stratigraphy is presented both as percentages and as "absolute" influx. Both the pollen and macrofossil data have been analyzed by numerical zonation procedures to reveal the major stratigraphic patterns with the two data sets. The vegetational reconstructions presented are based on the pollen percentage and influx data, on macrofossil assemblages, on comparisons of modern and fossil pollen spectra, and on the present ecology of the individual taxa concerned. From 20,500 to 14,700 yr ago, a mosaic of tundra—like vegetation prevailed, with wide—spread "tundra—barrens" of Dryas integrifolia, Arenaria rubella, Silene acaulis, and Vaccinium uliginosum var. alpinum. Between 14,700 and 13,600 yr ago, shrub vegetation with dwarf birch, Empetrum, willows, alder, and Shepherdia canadensis developed as a transitional phase prior to the establishment of spruce—dominated woodland 13,600 yr ago. Between this time and 10,000 yr ago, little change occurred in the upland vegetation, except for the expansion of some deciduous elements ° 12,250 yr ago. Local changes in wetland assemblages occurred, primarily in response to changes in lake level. At °10,000 yr ago, Pinus banksiana expanded at the expense of spruce to form a mixed coniferous—deciduous forest. Climatic interpretation of this vegetational development suggests a progressive increase in temperature since 14,700 yr ago. This unidirectional trend in climatic development contrasts with the glacial history of the state for the time period of interest, as the Lake Superior ice lobe advanced three times between 16,000 and 12,000 yr ago. The lack of correspondence between the pollen stratigraphy and the glacial history is discussed, and hypotheses are presented to explain this apparent anomaly.
Phytoplankton in an Oligotrophic Ocean: Observations and Questions
Authors: Venrick E. L.
Published: April 2006

Details of the vertical distribution of oceanic phytoplankton species are investigated by means of four stations occupied during June 1977 and August 1978 near 28°N, 155°W. Two distinct, recurring floral associations, separated by a region of rapid transition near or below 100 m, are identified. The associations are apparently related to the "nutrient limited" and "light limited" physiological regimes described previously. Inverse abundance relationships of congeners within the deeper association are compatible with the hypothesis of disequilibrium competitive interactions and community regulation. Among species of the shallow association congeners are positively associated and predation is postulated to be the important regulating mechanism.
A Reevaluation of the ‐3/2 Power Rule of Plant Self‐Thinning
Authors: Weller Donald E.
Published: April 2006

The self—thinning rule predicts that for a crowded even—aged plant population a log—log plot of average plant mass vs. plant density will reveal a straight "self—thinning" line of slope–3/2. The rule is supported by examples from many individual populations, and by the existence of an interspecific relationship that yields a line of slope–3/2 in a log—log plot displaying average mass and density data from many populations of different species. I examined and reanalyzed the evidence to evaluate the strength of support for this widely accepted rule. Some problems in fitting thinning lines and testing agreement with the rule have no truly satisfactory solution, but three improvements on commonly used methods were made: the analysis related stand biomass density to plant density because the alternative of relating average plant mass to plant density is statistically invalid; principal components analysis was used rather than regression, because regression relies on unrealistic assumptions about errors in the data; and statistical tests of hypotheses were used to interpret the results. The results of this reanalysis were that 19 of 63 individual—population data sets previously cited in support of the thinning rule actually showed no significant correlation between stand biomass density and plant density, and 20 gave thinning slopes significantly different (P < .05) from the thinning rule prediction. Four other analyses provided additional evidence against a single quantitative thinning rule for all plants: slopes of the thinning lines were more variable than currently accepted, differed significantly among plant groups, were significantly correlated with shade tolerance in forest trees, and differed among stands of the same species. The same results held for the intercepts of self—thinning lines. Despite the failure of the thinning rule for individual populations, the combined data for all populations are still consistent with an interspecific relationship of slope–3/2; therefore, the existence of the interspecific relationship does not necessarily support the within—population thinning rule. The within—population and interspecific relationships are apparently different phenomena that may arise from different constraints, so the two relationships should be tested and explained separately..
The Mole Crab Emerita talpoida (Say): A Case of Changing Life History Pattern
Authors: Diaz Humberto
Published: April 2006

Mole crabs of the genus Emerita are successful colonizers of exposed sandy beaches, in spite of the severity of the physical environment. An adult population of Emerita talpoida (Say) was studied for 2 yr to determine possible changes of its life history pattern as a consequence of its physically severe habitat. Adult populations were sampled in four localities on Bogue Banks, North Carolina, USA, monthly during 1972 and in March, June and September 1973. Size distribution–in spite of some transient differences in the abundance of the larger individuals–was similar at all localities in each month of the year, and underwent dramatic simultaneous changes in spring and summer. The changes in spring resulted from rapid growth of overwintering animals. Changes in summer were produced by the recruitment of new individuals and the death of many large ones. Although size distribution was similar at all localities, significant differences in abundance were found in each month for all sizes except the smallest, suggesting that recruitment was simultaneous and of equal magnitude all along Bogue Banks. In spring, ovigerous females were larger, and carried a greater number of larger eggs. However in summer females were more abundant and produced several clutches. Most recruitment occurred in September as a result of the summer spawning. A greater proportion of females was observed in spring and fall. The spring peak was caused by death of the larger males. The fall peak was caused by a large recruitment of females (63%). When males died in spring, they were about half the size of the largest females observed. No increase in the number of medium—size females was observed in spring. In both sexes the mortality rates were constant, but greater for males, resulting in a shorter life expectancy for the latter. Thus it appears unlikely that sex reversal in males occurs in Emerita talpoida. Survival curves indicate that if sex reversal occurs in this species it would happen at a constant rate in all age intervals. Sex reversal was not observed under laboratory conditions. Life table parameters calculated from data for 1972 indicate that the population has expanded in the recent past, assuming egg production to be independent of density. This result, along with the appearance of larger females in 1973 (which were less abundant in 1972) suggests that in 1972 the population was recovering from mortality probably caused by two hurricanes in the fall of 1971.
Field Tests of Neighborhood Population Dynamic Models of Two Annual Weed Species
Authors: Pacala Stephen W. , Silander J. A.
Published: April 2006

We report the results of a 4—yr study of the community dynamics of the annual weed species Abutilon theophrasti (velvet leaf) and Amaranthus retroflexus (pigweed). We calibrated neighborhood population dynamic models for communities of these species in the field and then tested the predictions of the calibrated models against census data from independent observations. We also analyzed the calibrated and tested models to predict long—term dynamics and to assess how spatially local interactions, growth, fecundity, survivorship, germination, seed dormancy, and dispersal each contribute to the community's dynamics and structure. We show that calibrated neighborhood models accurately predict dynamics in the field over a 4—yr period. Because the predictive spatial models reduce approximately to simple nonspatial models of competition, the spatial processes that govern the dynamics of velvet leaf and pigweed communities behave as simple nonspatial processes. The models predict that velvet leaf will eventually exclude pigweed because of an asymmetry in the magnitude of inter—individual interference affecting growth. We also show that velvet leaf monocultures would oscillate perpetually in the absence of delayed germination and that demographic stochasticity (May 1971) has little effect on the dynamics of the experimental species.
Size‐Dependent Processes Underlying Regularities in Ecosystem Structure
Authors: Dickie L. M. , Kerr S. R. , Boudreau P. R.
Published: April 2006

The structure of animal communities and the energy flux through them may be characterized by biomass ratios, ecological efficiencies, and production efficiencies of the component organisms. Here, we interpret these ratios in terms of the elementary processes of food intake, specific production rate, and gross growth efficiency that underlie them. Recent information confirms that the magnitude of all these processes is related to the average body mass of the organisms involved. However, our analysis shows that this well—known dependence reflects the influence of two different basic biological properties. One of these is the metabolism—body—size relation of individual that is familiar from physiology. The other less well—recognized property appears as an ecological population factor reflected in the distribution of particle sizes within animal groups in the community and is probably related to the relative sizes and distributions of predators and their prey. It appears that both the physiological and ecological size relationships have to be recognized as scaling factors in order to transform measures of biological production of various parts of communities into common terms for comparison. Current data on the generality and stability of community structure and production suggest that by using this twofold size scaling, trophic energy flow within the community can be determined from the distribution of body sizes without the necessity of specifying trophic levels of the organisms involved. The ecological size scaling can be seen as an index of the system nature of ecosystems.
A Model of Competition Incorporating Plasticity through Modular Foliage and Crown Development
Authors: Sorrensen-Cothern Kristin A. , Ford E. David , Sprugel Douglas G.
Published: April 2006

The model of competition for light presented here uses modular autonomy to incorporate plasticity in plant growth under competition. Once plants are characterized as composed of modules, then model structure for competition changes in a fundamental way. Interactions between the plant module and its local resource environment must be modeled rather than the traditionally viewed interactions between whole plants and their neighbors. We assume that a plant module interacts with its local resource environment regardless of whether this environment was altered by a neighbor or by the same plant. Two spatial processes are considered: resource acquisition and growth. The spatial pattern of resource acquisition by a module determines a growth and allocation pattern, e.g., the elongation of branches into a gap. The spatial structure of a module and its connection to the whole tree then determines the pattern of resource distribution and resource acquisition of the next time step.Plasticity of plant growth is incorporated by variation in both the efficiency of resource capture of modules and patterns of resource allocation for individuals of different canopy positions and results in individuals in the community having different spatial structures. The model simulates the three—dimensional development of tree crown structure over time. It is applied to the 30—yr development of a dense, spatially aggregated stand of Abies amabilis beginning with an initial pattern of seedlings. The importance of incorporation of plasticity is apparent when the model output is compared to observed height distribution and crown structure data. Simulations indicate that asymmetrical crown development, one form of plasticity, is advantageous to stand productivity and becomes more advantageous as the degree of spatial aggregation in the initial spacing of trees increases.
Carbon Dioxide and Methane Exports from a Southeastern Floodplain Swamp
Authors: Pulliam William M.
Published: April 2006

Patterns and rates of generation of CO2 and CH4 by aerobic and anaerobic soil respiration are a significant gap in knowledge of floodplain carbon dynamics. Gaseous and hydrologic exports of CO2 and CH4 from the forested floodplain of the Ogeechee River in Georgia, USA, were studied from July 1987 to September 1989. Net emissions to the atmosphere were measured with short (10—20 min) static chamber incubations. CO2 emissions were highly seasonal, with largest rates during summer, and were strongly correlated with soil temperatures. Annual total CO2 emissions were similar in both years of the study, and averaged 919 g/m2. The contribution of live root respiration to this total was estimated with in situ incubations of attached roots excavated from the soil. Over 55% of the total CO2 flux appeared to arise from live roots rather than mineralization of soil organic matter. Significant atmospheric CH4 fluxes were found only at flooded sites. CH4 emissions were highly variable, with high rates of release of methane carbon (up to 271 mg · m—2 · d—1) occurring irregularly during the warmer months. The temperature effect on CH4 emissions appeared to be a step function. No significant CH4 emissions occurred when soil temperatures were below 15°C; during warmer periods emission rates were generally positive, but showed no additional correlation with temperature. This effect is hypothesized to represent an interaction of the rates of oxygen consumption and replenishment in the soil. Spatial variability in CH4 emissions was also large. Over 90% of the total floodplain CH4 emissions came from the 30% of the floodplain that was most frequently inundated. Annual total fluxes of CH4 carbon from low habitats averaged 17 g · m—2 · yr—1. Methane oxidation rates were estimated in floodplain surface waters by in situ bottle incubations. Roughly half of the CH4 that entered the water column was consumed without reaching the atmosphere. Hydrologic exports of CO2 and CH4 via surface and groundwater were small, representing ≈1—2% of total export for both species, and were much less important than fluvial exports of organic carbon. Overall, floodplain detrital carbon processing was dominated by aerobic respiration and gaseous CO2 export, although methanogenesis did constitute up to 20% of total soil respiration at some sites.
The Characterization of Vole Population Dynamics
Authors: Mihok Steve , Turner Brian N. , Iverson Stuart L.
Published: April 2006

The population cycles of meadow voles (Microtus pennsylvanicus) were studied in southeastern Manitoba, Canada, from 1968 to 1978 on a 32—ha old field and in surrounding boreal forest. Vole density was monitored on mark—recapture live—trapping at 2— to 4—wk intervals throughout the year. This was supplemented by a 3—d spring and a 30—d summer snap—trapping survey. Multiannual and annual fluctuations in density of Microtus were independent of a diversity of patterns seen in other small mammal species. Principal components analysis of demographic statistics was used to characterize changes in seasonal reproduction, survival, and dispersal that accounted for the observed numerical fluctuations. Conditions during a catastrophic winter population decline in 1970—1971 were compared with those in 1974—1975, when numbers recovered quickly after a modest spring decline. Voles were in good condition before and during both declines, as evidenced by normal body composition indices. Large body masses, characteristic of peak populations, preceded both population declines. The main conditions associated with the 1970—1971 decline were unusual patterns in social behavior and dispersal. Changes in social behavior in the field were reflected in unprecedented numbers of multiple captures in Longworth traps before and during this decline. Field observations were supported by unusually high frequencies of amicable behavior in neutral arena bouts staged between males removed from a control population. Little dispersal was detected with conventional live—trapping during the winter period of chronic mortality in 1971. In contrast, a period of acute mortality, resulting in the near extinction of the population in March 1971, was associated with considerable dispersal. We propose two alternative hypotheses consistent with the unpredictable and episodic nature of vole population declines: (1) an immunological dysfunction exists in voles that makes them susceptible to naturally occurring microparasites or (2) opportunistic, pathogenic microparasites exploit the changes in dispersal and social contacts that occur as a normal part of the vole population cycle.
The Structure and Regulation of Some South American Kelp Communities
Authors: Dayton Paul K.
Published: April 2006

The main objective of this study was to evaluate how physical stress and herbivores influence the distribution, abundance, size frequency, and mortality of the giant kelp, Macrocystis pyrifera, in the southeast Pacific. These factors were studied for the kelp and the echinoid herbivore Loxechinus albus over a wide latitudinal range (56°—42° S) of South America on RV Hero cruises in 1972 and 1973. There were large kelp forests with many large plants in the southern Isla de los Estados and Tierra del Fuego sites. Sources of kelp mortality in these sites include entanglement with drift plants and heavy encrustation of bivalves. This resulted in a considerable amount of drifting kelp, and the sea urchins appeared to have abundant food and did not attack living kelp plants. Nevertheless, the urchin densities usually were relatively low and the Loxechinus size frequencies skewed to larger size classes, suggesting that their populations may be limited by larval availability in the Westwind Drift. There were also some large kelp forests in the northern Golfo Corcovado and Isla Chiloe areas, but here the kelp forests seemed relatively ephemeral and Loxechinus appeared to be harvested by humans. The intermediate latitudes (54°—46° S) in areas semiexposed to oceanic waves were characterized by situations in which Loxechinus overexploit the kelps and maintain urchin—coralline algae "barren grounds." In these areas kelps occur only where urchin access is restricted by wave exposure, ephemeral clumps of Desmarestia ligulata, and rarely, by a predator, the asteroid Meyenaster gelatinosus. In many areas the shallow distribution of Macrocystis was restricted by competition with the large fucoid Durvillaea antarctica. These relationships were evaluated by removal and addition experiments. Much more important than latitudinal relationships to both kelp and urchin distribution and abundance patterns were exposure gradients, from shores subject to strong oceanic swells to protected fjords. Transect data suggest that Loxechinus disappear from protected waters before Macrocystis. Thus in some semiprotected habitats there are very dense patches of kelps without grazers; kelp removal experiments in these habitats suggest strong density—dependent kelp interactions. In still more protected sites, the Macrocystis growth form changes, the plants appear to have low fertility, and there is very low recruitment. Summarizing, the Loxechinus population seems restricted by larval recruitment in the face of the Westwind Drift in the far south, perhaps by sedimentation or fresh water in protected fjords, and by human fishing in the north. The very low Loxechinus densities in the far south are correlated with large kelp forests in which the main kelp mortality results from drifting Macrocystis plants. The kelp populations appear limited by physical factors in the fjords and by Loxechinus grazing in most other areas.
Ecological Interactions between Plants and Hummingbirds in a Successional Tropical Community
Authors: Feinsinger Peter
Published: April 2006

At Monteverde, Costa Rica, 10 successional plant species used 14 hummingbird species for pollination. Displacement among flowering seasons suggests that the plants influenced hummingbirds to abandon another. There was no evidence that the flowering of one plant influenced hummingbirds to abandon another Pollination is simultaneously flowering plants likely suffered nonetheless, since birds tended to move indiscriminately among flowers of different species and could lose much pollen between successive visits to conspecific plants. This may have led to scatter in flowering peaks by favoring the quick establishment of plant colonists with unique flowering seasons over colonists whose flowering seasons coincided with those of established species. The continuous supply of nectar provided by staggered flowering peaks maintained a continuous supply of hummingbirds competing for nectar. Even inconspicuous plants with few flowers received sufficient hummingbird visits for moderate to high potential rates of outbreeding. At large, flower—laden trees and shrubs, hummingbirds defending feeding territories evidently effected much inbreeding, but movements of intruders between territories kept inbreeding from becoming absolute. Nectar secretion rates varied widely among flowers of each of the 5 plant species in which nectar volume was measured. Many flowers produced little or no nectar, while a few secreted quite copious volumes. This "bonanza" pattern may benefit plants by reducing caloric expenditures on nectar while increasing the duration of hummingbirds' foraging bouts. The latter possibility was tested and verified experimentally with artificial flowers exposed to a free—living hummingbird on Trinidad, West Indies. When pollinators are abundant, plants with "bonanza" patterns can attract consistent visitors and rare, inconspicuous plants can count on consistent service. At Monteverde, the unspecialized, opportunistic nature of both plants and birds assured abundant hummingbirds and resulted in a well—integrated complex of plants and pollinators despite the transient nature of the successional habitats.
Late Quaternary Vegetational History of Illinois
Authors: King James E.
Published: April 2006

Pollen diagrams from the Prairie Peninsula in Illinois record the climatically related vegetation shifts that have occurred since the late Pleistocene. They indicate that the major period of prairie development started between 8500 and 7900 BP, apparently occurring first along the southern margin. These events mark the beginning of the Hypsithermal interval and are correlated with the final disintegration of the Laurentide ice sheet and the establishment of the postglacial system of atmospheric circulation over North America. The late—glacial vegetation was spruce woodland in the north and open spruce woodland/tundra in central Illinois. These vegetation communities disappeared from the state in a northward direction between 14 000 and 10 900 BP. They were followed in northern Illinois by Pinus, Abies, Betula, and Fraxinus; in central Illinois Fraxinus expanded in the lowlands while the uplands remained relatively treeless. These assemblages, which persisted longer in the south than in the north, were subsequently replaced first by a mixture of cool temperate, then warm temperate deciduous trees as climatic amelioration continued. By 9000 BP, Illinois was dominated by deciduous forest. In response to Hypsithermal climatic stress, prairie vegetation began replacing deciduous forest about 8300 BP on the uplands in central Illinois and by 7900 BP xeric oak—hickory forest became dominant in northern Illinois. This is the beginning of the Prairie Peninsula as a discrete floristic area in Illinois. About 5000 BP the southern border of the Prairie Peninsula experienced increased moisture and renewed forest development suggesting a western contraction of the prairie margins. Central Illinois, however, remained grassland to the present. Between 900 and at least 400 yr ago an indicated trend toward cooler temperatures is correlated with late stages of the Neoglacial. Pollen evidence from northern Illinois and adjacent Lake Michigan indicates the reappearance or increase in Betula, Pinus, Picea and Larix. This short cool episode appears to end prior to the beginning of large—scale historic land clearance, about 140 yr ago, as the evidence for a vegetational readjustment to warmer climate is truncated by the logging of the forests, the plowing of the prairies and the resultant dramatic increase in Ambrosia pollen.
Modeling of the current limitations of PEFC
Authors: Zhukovsky K.
Published: April 2006

PEFC operation in the regime of limiting current has been considered. The phenomenon of oxygen depletion on the cathode is considered responsible for the highest current limits of the cell. The performance of the cell appears to depend strongly on the geometry of the gas diffuser and supply channels. The study of the most promising geometric configurations of the electrodes is carried out. We consider serpentine, interdigitated, and interlaced designs of the gas supply in the electrode. The effect of the geometry on the liquid water removal from the electrode and air pressure in gas channels are studied to identify the best geometry of the gas supply net in terms of the maximum cell current. A comparison between model predictions and experimental data is carried out. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Intensification of catalytic olefin hydroformylation in CO2‐expanded media
Authors: Jin Hong , Subramaniam Bala , Ghosh Anindya , Tunge Jon
Published: April 2006

CO2‐expanded liquids (CXLs) are demonstrated to be effective reaction media for the catalytic hydroformylation of 1‐octene. The performance of several rhodium catalysts, Rh(acac)(CO)2, Rh(acac)[P(OPh)3]2, Rh(acac)(CO)[P(OAr)3], and two phosphorous ligands, PPh3 and biphephos, was compared in neat organic solvents and in CXLs wherein more than 50% of the solvent volume is replaced with dense CO2 at relatively mild temperatures (30–90°C) and pressures (<12 MPa). For all catalysts, enhanced turnover frequencies (TOFs) were observed in CXLs. For the most active catalyst, Rh(acac)(CO)2 modified by biphephos ligand, the selectivity to aldehyde products was improved from approximately 70% in neat solvent to nearly 95% in CXL media. The enhanced rates and selectivity are attributed to increased syngas availability in the CXL phase. In experiments performed without added solvent, a TOF maximum was observed at an optimum CO2 content. It appears that at higher than optimum CO2 content, the TOF decreases as a result of dilution of substrate by CO2, whereas at lower than optimum values the TOF is limited by reduced syngas availability. The observed TOF (∼300 h−1), n/i ratio (>10), and aldehyde selectivity (∼90%) at the optimum CO2 content were either comparable to or better than values reported with other media and catalysts. Furthermore, the operating pressure (3.8 MPa) and temperature (60°C) for the CXL process are significantly milder than those reported for industrial hydroformylation processes. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Enthalpy change on mixing a couple of S‐ and R‐enantiomers of some chiral compounds at 298.15 K
Authors: Kimura Takayoshi , Khan Mohammed Abdullah , Ishii Masakazu , Kamiyama Tadashi
Published: April 2006

Enthalpy change on the mixing of R‐ and S‐enantiomers of chiral liquid compounds such as dimethyl malate (1), methyl 3‐hydroxylbutanoate (2), 2‐butanol (3), ethyl 4‐chloro‐3‐hydroxylbutanoate (4), 1,3,3‐trimethylbicycle‐[2.2.1]heptan‐2‐one (5), 3,7‐dimethyl‐6‐octenal (6), and 8‐bromo‐2,6‐dimethyl‐2‐octene (7) is measured over the entire range of mole fractions at 298.15 K, albeit very small values. The mixing of chiral liquids of R‐1 + S‐1, R‐2 + S‐2, R‐3 + S‐3, R‐6 + S‐6, and R‐7 + S‐7 produces enthalpic destabilization over the entire range of mole fractions, while that of R‐4 + S‐4 and R‐5 + S‐5 shows enthalpic stabilization over entire compositions. Enthalpy change on mixing at an equimolar concentration and the intermolecular interaction obtained by the molecular mechanics calculations show a linear correlation, except for a few compounds measured. Chirality, 2006. © 2006 Wiley‐Liss, Inc.