bluuebunny/crossref_metadata_2025 huggingface dataset:
Annual to decadal-scale variations in northwest Atlantic sector temperatures inferred from Labrador tree rings
Authors: D'arrigo Rosanne D. , Cook Edward R. , Jacoby Gordon C.
Published: December 2007

Temperature-sensitive maximum latewood density chronologies from sites near tree line in Labrador are used to infer past changes in warm-season surface air and sea surface temperatures for the northwest Atlantic. Temperatures are reconstructed for the Grand Banks region based on density records from southern Labrador, while a density series from near Okak Fiord, northern Labrador, is used to infer past temperature variations for north-coastal Labrador and the adjacent Labrador Sea. The Labrador chronologies show good agreement with annual and decadal-scale temperature fluctuations over the recent period of instrumental record, and extend this temperature information into the past by several centuries. The lowest density value at the Okak site occurs in 1816, known as the "year without a summer" in eastern North America. Spectral analyses reveal statistically significant variations with periods of around 8.7, 18–22, and 45–66 years. These fluctuations are in general agreement with those identified in several instrumental and modeling analyses of North Atlantic climate.
Time-restricted seed regeneration of Scots pine in sites dominated by feather moss after clear-cutting
Authors: Nilsson Marie-Charlotte , Steijlen Ingeborg , Zackrisson Olle
Published: December 2007

Scots pine (Pinussylvestris L.) were selectively seeded in 1990, 1991, 1992, and 1994 in bottom layer vegetation of Pleuroziumschreberi (Bird.) Mitt, in a clearcut created in 1989 and in an adjacent undisturbed Scots pine forest of Vaccinium type, in northern Sweden. Seedlings from the 1990 seeding established considerably better on the clearcut than in the forest. In contrast, seeding done in 1991, 1992, and 1994 gave no significant difference in seedling establishment between the two sites. Seedlings that established in the clearcut in 1990 grew significantly larger and had a higher content of macro- and micro-nutrients than those in the forest. For seedlings that established in 1992, biomass and nutrient content of seedlings in the clearcut did not differ from those in the forest. Seedlings established in the clearcut in 1990 increased their nutrient content in relation to seed supply, while seedlings established in the clearcut in 1992 and those in the forest had in general gained less or even lost nutrients (especially P) in relation to seed reserve. These results indicate that Pleuroziumschreberi-dominated microsites can constitute a favourable microhabitat for pine regeneration following stand disturbance, although the positive effect quickly diminishes with time after disturbance. The higher establishment and growth of emerging seedlings the 1st year after cutting compared with later established cohorts in the clearcut may be caused by changes in nutrient availability. We propose that environmental stress after cutting temporarily diminishes the effect of the nutrient barrier formed by Pleuroziumschreberi, ericoid mycorrhiza, and ericaceous dwarfshrubs. We conclude that successful natural pine regeneration in Pleuroziumschreberi-dominnted vegetation induced by clear-cutting can be severely time restricted. This is an important consideration when dealing with forestry methods that depend on natural regeneration.
Spatiotenraporal growth dynamics and disturbances in a subalpine spruce forest in the Alps: a dendroecological reconstruction
Authors: Cherubini Paolo , Schweingruber Fritz H. , Piussi Pietro
Published: December 2007

The recent history was reconstructed and the large-scale disturbance regime evaluated of a subalpine spruce (Piceaabies (L.) Karst.) stand in the eastern Italian Alps. A 0.4-ha plot was cut for experimental purposes. Living trees, dead stems, and decaying stumps were identified, labeled, and mapped. Cross sections were taken from 117 trees. Ring-width measurements and skeleton plot analyses were performed. Past cutting in the stand was reconstructed from growth releases after suppression and the presence of synchronous scars. The site was heavily impacted by human activities. Timber cutting done on small patchy areas in the past did not negatively affect the stability of the stand. The presence of a waiting period in many trees shows that they grew slowly under a loose canopy. After a waiting period, a gap formed allowing their growth. The seedlings and saplings waiting under the canopy are very important to assure spatiotemporal stability. Skeleton plots are essential for a high resolution record of growth dynamics and disturbances. Basal cross sections contain more qualitative information than cross sections taken at higher stem levels. The method may be applied to reconstruct stand dynamics in other regions, where historical information is scarce or completely missing.
Age structure and growth of understory white spruce under aspen
Authors: Lieffers Victor J. , Stadt Kenneth J. , Navratil Stan
Published: December 2007

Juvenile white spruce (Piceaglauca (Moench) Voss) under an aspen (Populustremuloides Michx.) overstory were studied in nine boreal mixedwood stands in west-central Alberta. In each stand, 50 understory white spruce were cut for stem analysis at ground level, 30, 70, 130 cm, and every 100 cm to tree height. In four stands, recruitment of these understory spruce occurred immediately after the disturbance, while in others the recruitment was delayed several decades. The period of recruitment was as short as 15–20 years or continued for decades, producing an uneven-aged understory. Trees initiated on rotten logs had a slightly lower initial annual diameter increment but did not differ in height growth compared with those initiated on normal forest floor. The annual height increment increased as the trees grew in height, presumably as they overtopped successive layers of shading vegetation. When seedlings were less than 30 cm tall they grew less than 10 cm per year, but attained growth rates of 30 cm per year or more when they were taller than 230 cm. Height growth rates for these understory trees were comparable to reported growth rates of white spruce of similar size and age from clearcut areas.
The effect of humidity on photosynthesis and water relations of white spruce seedlings during the early establishment phase
Authors: Marsden B.J. , Lieffers V.J. , Zwiazek J.J.
Published: December 2007

Newly transplanted, 3-year-old bare-root white spruce (Piceaglauca (Moench) Voss) seedlings were grown in three levels of absolute humidity difference (AHD), under water-stressed and well-watered conditions in growth chambers. Stomatal conductance to CO2 as well as net assimilation were more than twice as high in the low AHD treatment (6.8 μg H2O•cm−3) as in the high AHD treatment (21.0 μg H2O•cm−3). Transpiration rates were uniform among humidity treatments, but in the low AHD treatment water use efficiency was more than double that of the high AHD treatment. Water use efficiency was greatest in the low AHD conditions, in the water-stressed seedlings, and during the time immediately after planting. There were no differences in the number of new roots produced among humidity treatments, despite the different levels of photosynthesis. In the stress treatment, bud flush of seedlings in the high AHD treatment occurred 3 days later than in the low AHD treatment. A field study on the effects of varying aspen (Populustremuloides Michx.) canopies on humidity levels showed that AHD under partial and full canopies was lower than that of the clearcut. Results suggest that silvicultural treatments that promote higher humidity levels on planting sites should improve white spruce seedling photosynthesis immediately after planting.
Effect of colonizing tree species on soil nutrient availability in a clay soil of the boreal mixedwood
Authors: Paré David , Bergeron Yves
Published: December 2007

Soil nutrient availability was assessed around stems of trembling aspen (Populustremuloides Michx.), white spruce (Piceaglauca (Moench) Voss), and paper birch (Betulapapyrifera Marsh.) that regenerated after fire 49, 77, and 123 years ago on a clayey soil of the southern boreal forest. For all stand ages, forest floor pH was greater by 0.5 unit under aspen than under other species, while the accumulation of organic matter and nutrients was generally greater in the forest floor of spruce. With time since fire, forest floor pH and mineral soil reserves of nitrogen (N) and exchangeable calcium declined significantly, while the C/N ratio increased, perhaps as a result of nutrient immobilization in the aggrading biomass. Net N mineralization and nitrification, measured by aerobic laboratory incubations, were higher under birch and aspen than under spruce in the forest floor and the mineral soil of the youngest stand (49 years old). However, in older stands, these parameters were significantly lower, and no significant differences were found between soils of deciduous and coniferous species. These results suggest that a decrease in N availability with time since fire was caused by factors other than the generally assumed succession to coniferous trees.
Are markets for stumpage informationally efficient?
Authors: Yin Runsheng , Newman David H.
Published: December 2007

This paper tests autocorrelation of stumpage price series and real rates of change in stumpage prices over various lags. We find that stationarity exists in all the 14 southern markets examined, and all of the coefficients of lagged returns are negative and most of them are significant at different lags. These results lead us to accept the necessary condition for informational inefficiency of the stumpage markets, stationarity, and to realize the existence of mean reversions of a slowly decaying component in the stumpage price series. We also discuss the implications of our results for some important problems of forest economics, such as price-responsive tree cutting and the use of capital asset pricing model, and for the data treatment and analytical approaches in previous studies. Given the limitations of our data, however, we stop short of examining whether there are time-varying equilibrium expected returns or whether stumpage markets are sufficiently inefficient.
In situ formation of organically bound halogens during decomposition of Norway spruce needles: effects of fertilization
Authors: Öberg G. , Nordlund E. , Berg B.
Published: December 2007

Past years of research indicate that halogenation of organic matter is a general occurrence in soil. As this is a virgin research field, little is known about, for example, the possible relation to the turnover of organic matter, influence of environmental parameters, or ecological role. The aim of the present paper was to study the influence of fertilization on in situ formation of organically bound halogens and its possible relation to decomposition of organic matter. Total amount of organically bound halogens was determined in nutrient-rich and nutrient-poor spruce litter incubated up to 4 years in a fertilized plot and a control plot. It was found that the concentration of organically bound halogens increased throughout the incubation period, and the increase was significantly larger in the control than in the fertilized plot. This resulted in an accumulated increase in the control plot that was approximately twice as large (ca. 200 μg Cl/g dry mass) as that in the fertilized plot at the end of the incubation period. The changes in absolute amounts were complexly related to litter mass loss. This strongly indicates that there are multiple underlying processes and that halogens are both incorporated into and released from organic matter during decomposition. Calculated on a daily basis, the rate at which the amounts of organohalogens changed showed a seasonal pattern, with a pronounced increase during late summer and autumn. After 1 to several years, a net decrease was observed, particularly in the summer period. This decrease appeared earlier and was more pronounced in the fertilized plot than in the control plot, strongly indicating that mineralization of organically bound halogens, i.e., release of inorganic halides, was enhanced by fertilization. In the litter incubated in the control plot, the absolute amounts increased in relation to lignin degradation. In combination with previous findings, the results of the present study suggest that formation of organically bound halogens is conducted by organisms responsible for lignin degradation. Furthermore, the findings indicate that fertilization may favour organisms that degrade organically bound halogens at the expense of organisms that cause the formation of such compounds.
A vegetation model for the Sayan Mountains, southern Siberia
Authors: Monserud Robert A. , Tchebakova Nadja M.
Published: December 2007

A mountain vegetation model driven by regional climatic parameters was developed for predicting the geographic distribution of the numerous ecosystems of the Sayan Mountain system in southern Siberia. Meteorological data are drawn from normal records of monthly means. Four climatic variables were interpolated to a 10′ by 10′ grid: temperature, precipitation, vapor pressure, and cloudiness. In addition, albedo was derived by 100-m elevation classes for both windward and leeward slopes as a function of the general type of vegetation surface and the dates of snow occurrence. Ecosystems were classified using a two-dimensional climatic ordination. The first dimension was growing degree-days above a 5 °C threshold, and the second was Budyko's dryness index, which is based on annual radiation balance and annual precipitation. The patterns of predicted vegetation corresponded rather well to observed mapped vegetation. Overall κ statistics indicated agreement with observed vegetation that varied from fair at the finest resolution (10′ by 10′ cells) to good at intermediate resolution (30′ by 30′ cells and 1° by 1° cells) to very good at the coarsest resolution (2° by 2° cells). Focusing on individual vegetation classes, agreement was good to very good for each vegetation class at intermediate resolutions and very good to excellent for each vegetation class at the 2° by 2° resolution. Thus, the general location, pattern, and overall distribution of these mountain ecosystems was accurately predicted. This approach for predicting the spatial distribution of biomes was successfully applied at both the global and subcontinental scale. The successful extension of Budyko's radiation balance approach to mountainous terrain on a finer resolution regional scale indicates the generality of the approach.
The recent sugar maple decline in southern Quebec: probable causes deduced from tree rings
Authors: Payette Serge , Fortin Marie-Josée , Morneau Claude
Published: December 2007

We used tree-ring chronologies from sugar maple (Acersaccharum Marsh.) stands showing various degrees of dieback (i.e., 16 sugar maple chronologies from healthy trees and 11 from damaged trees), distributed throughout the species range in southern Quebec, to analyze the spatial extent and timing of the recent sugar maple decline. Furthermore, six tree-ring chronologies of American beech (Fagusgrandifolia Ehrh.) from six damaged sugar maple stands were used to compare for differential responses associated with factors such as insect defoliation (from the forest tent caterpillar, Malacosomadisstria Hbn., for which American beech is a nonpreferred species), drought, and other climatic events. It was found that several small-scale drought-induced disturbances occurred repetitively over the last 100 years in the western part of the species range in southern Quebec. Most sugar maple chronologies from stands located west, north, and south of Québec City also show extreme narrow tree rings, indicating the incidence of three large and deep growth depressions from the early to mid-1910s, mid-1950s, and early 1980s. The factors explaining the large growth depression of dominant sugar maple of the early 1980s, in the region where the 1980s maple decline was the most severe, are likely associated with the synergistic influence of drought and insect defoliators. The recovery of sugar maple stands from the 1980s growth decline emphasizes the positive responsiveness of the robust native trees to frequent natural disturbances. The 1980s maple decline corresponds to the category of natural disturbances affecting stand dynamics by the combination of events such as drought and insect infestations, and possibly (but to a minor extent) winter thaw-frost, which has yet to be demonstrated, rather than by anthropogenic pollution.
Temporal and spatial harvesting of irregular systems of parcels
Authors: Snyder Stephanie , ReVelle Charles
Published: December 2007

Spatial management issues have assumed a central position in planning for forest ecosystems in the United States on both public and private lands. The arrangement of management activities, especially harvesting activities, can often have adverse impacts on other neighboring areas of the forest. Thus, spatially explicit programming models, which can account for or prevent certain arrangements of activities or land allocations through the use of harvest adjacency constraints, have received considerable attention in the literature. The need for spatial specificity in programming models has led to the development of integer programming or mixed integer programming models. Given that integer programming problems are often viewed as a difficult class of problems to solve, heuristic solution methods have most often been used to solve spatially constrained forest management models. In this paper, a discrete (0–1) integer programming model that maximizes harvested timber volume over a multiperiod time horizon subject to harvest adjacency constraints is developed and tested for irregular, realistic systems of parcels. This model performed well computationally for many example configurations and was solved exactly using the simplex algorithm and limited branching and bounding. Certain spatial configurations with long time horizons did, however, require a nontrivial amount of branching and bounding. The model was tested using both contrived and real spatial data sets.
Provenance tests as Indicators of growth response to climate change in 10 north temperate tree species
Authors: Carter K.K.
Published: December 2007

Thirteen series of multilocation provenance test plantations, representing 10 tree species common to eastern North America, were analyzed to determine the effect of variation in average annual minimum temperature on height growth of trees from known seed source locations. Regressions were developed to predict provenance height, based on the temperature differentials between seed source locations and provenance locations. Regression equations for 12 of the 13 provenance test series were sigificant (p < 0.01) and accounted for an average of 29% of the height variation among provenances. For 8 of the 10 species examined, an increase in average annual minimum temperature is projected to result in a decline in tree height growth, relative to an adapted source.
Reproductive success of orchard and nonorchard pollens during different stages of pollen shedding in a Scots pine seed orchard
Authors: Harju Anni M. , Nikkanen Teijo
Published: December 2007

The reproductive success of orchard and nonorchard pollens was studied in seeds from megastrobili exposed during different stages of pollen shedding in a Pinussylvestris L. seed orchard. Wind pollination was controlled experimentally by isolating and then temporarily exposing the megastrobili to four different stages of pollen shedding by orchard trees. The amount of pollen contamination in the seed crop was determined using isozyme markers and an undetected gamete model. The estimated level of pollen contamination was 48% when megastrobili were exposed during the entire pollination season. Contamination was highest (60%) when megastrobili were exposed before actual pollen shedding by orchard trees, and lowest (27%) in seeds from megastrobili exposed during maximum pollen shedding by orchard trees. Reproductive success was measured several ways: as the total number of seeds produced in each treatment, as the ratio or proportion of mature cones per megastrobilus, and as the number of seeds produced per cone or megastrobilus. In 1991, reproductive success was highest before maximum pollen shedding by seed orchard trees. Pollen shedding by orchard trees occurred a few days after most megastrobili became receptive.
Striped maple: shoot growth and bud formation related to light intensity
Authors: Wilson B. F. , Fischer B. C.
Published: December 2007

Terminal shoot growth and bud formation in striped maple (Acerpensylvanicum) were followed both in vigorous and suppressed forest trees and in suppressed trees grown in the greenhouse and garden under 10 light intensities from 6 to 82% of solar radiation in the open. All buds contained (1) a pair of preformed early leaves that grew rapidly and (2) a pair of rudimentary primordia that became either bud scales in suppressed trees, after abortion of the blade, or a second pair of leaves in vigorous or released trees. The fate of the rudimentary primordia could be regulated by light intensity. They formed bud scales at 6% light or leaves at about 18% light. Maximum height growth and leaf pair formation occurred at 30–60% solar radiation in the open, although the first internode was longest under the lowest light. When leaf production stopped, bud formation was similar in vigorous and suppressed trees. The inner and outer bud scales and the pair of preformed early leaves were produced at 2- to 4-week intervals. The rudimentary primordia were not formed until after an interval of 8–12 weeks, in late summer near the end of bud formation.
Influences du couvert forestier sur la croissance de quelques résineux dans le jeune âge
Authors: Aussenac G.
Published: December 2007

not available
Critical frost temperatures for Douglas-fir cone buds
Authors: Timmis Roger
Published: December 2007

Forest temperature for 50% kill (LT50) of female buds as determined by laboratory freezing tests in 1973–1975 ranged between −19 and −23 °C for five clones from mid-December to early March. Hardiness then decreased at 1.6 °C per week to an LT50 of −6.5 °C by the time of first bud swelling in late April. Throughout flowering, LTM remained at −4.5 and LTio at −2.7 °C. Male and vegetative buds were respectively about 1.5 and 4 °C hardier. Preliminary frost protection requirements have been defined so as to ensure 90% female bud survival on 80% of the clones.
Upland–lowland ecotypes not well developed in black spruce in northern Ontario
Authors: Fowler D. P. , Mullin R. E.
Published: December 2007

Seed collected from 30 stands of black spruce, 15 upland and 15 lowland, was tested by germination, nursery performance at two nurseries, and field planting at three locations; results were measured to the 5th and 10th year after planting.Significant differences (seed size, germination, seedling size, survival, and height growth) were found between the three geographical locations: Cochrane, Geraldton, and Thunder Bay. Only very minor differences were found between upland and lowland types. Strong significant differences were found between individual collection stands, indicating that superior stands for seed collection could be located and preserved.
Natural variation in balsam fir foliar components of dietary importance to spruce budworm
Authors: Shaw G. G. , Little C. H. A.
Published: December 2007

Year-to-year, geographical, and local variations in foliar concentrations of crude fat, nitrogen, total sugars, and starch and in foliar caloric value were determined for maturing, current-year needles of balsam fir (Abiesbalsamea L.). All except geographical variations proved to be statistically significant. Seasonal trends of chemical concentrations in maturing needles were in agreement with previous findings.Much of the variation in foliar caloric value could be explained by changes in foliar concentration of crude fat.Year-to-year changes in foliar nutrients may influence spruce budworm population dynamics.
Distribution and phenolic composition of sapwood and heartwood in Abiesgrandis and effects of the balsam woolly aphid
Authors: Puritch George S.
Published: December 2007

The distribution of sapwood and heartwood was analyzed at three different height levels in Abiesgrandis infested and non-infested with balsam woolly aphid. In non-infested trees, there was a highly significant regression between percentage heartwood age and disk age and a less significant regression between percentage heartwood area and disk area. Aphid infestation increased both the number of annual rings of heartwood and the heartwood area. The amount of heartwood in the infested trees was highly variable and dependent upon the degree of aphid infestation. Phenolic composition of A. grandis was similar to western hemlock, with heartwood containing matairesinol, hydroxymatairesinol, conidendrin, and an unknown phenolic glucoside. Sapwood contained several leucoanthocyanidins. Aphid infestation did not alter the phenolic composition of the heartwood, but it did cause the occurrence of a new phenolic in the sapwood. The possible causes of the increased amounts of heartwood in infested trees are discussed.
Variation in balsam fir provenances planted in New England
Authors: Lowe W. J. , Hocker Jr. H. W. , McCormack Jr. M. L.
Published: December 2007

After 3 years in the field, survival, date of shoot growth initiation, and total height of 15 provenances planted at three locations indicate moderate to large provenances effects. Relative provenance performance varied among locations for survival and total height but not for flushing date. Regression and correlation analyses indicated that both the temperature and moisture regimes at seed origin have acted as selective forces on the native population. Time of shoot growth initiation has been mainly influenced by the temperature regime, while total height was generally related to the moisture regime. Survival was not associated with any of the climatic variables used in the study.
Evidence for the presence of cyclic adenosine 3′,5′-monophosphate and its metabolism in loblolly pine (Pinustaeda L.) callus
Authors: Smeltzer Richard H. , Johnson Morris A.
Published: December 2007

Evidence is presented suggesting the occurrence of cyclic adenosine 3′,5′-monophosphate (cAMP) and adenyl cyclase activity in loblolly pine (Pinustaeda L.) callus cultures grown aseptically on a defined medium. The presence of enzymes in the callus capable of catalyzing cAMP hydrolysis also was detected. Adenosine was the most stable product resulting from cAMP hydrolysis. A direct relationship was found between apparent cAMP concentration and the rate of fresh weight increase of dark-grown callus during a 6-week passage.
The feeding impact of spruce budworm on balsam fir
Authors: Miller C. A.
Published: December 2007

Previous studies of budworm impact on balsam fir stands have correlated the probability of tree damage and mortality with only a few broad stand characteristics. Improved predictability may be obtainable from a model incorporating foliage production of fir, budworm feeding rate, and tree vulnerability. Some data are presented on the first two variables with comments on further research requirement.
Productivity of capital and labour in the Canadian forest products industry, 1965 to 1972
Authors: Sandoe Michael , Wayman Morris
Published: December 2007

This paper presents labour productivity data for several wood product industries, namely sawmilling, veneer and plywood, millwork, pulp and paper, and wrapping paper and paperboard. They registered respective gains of 2.5, 8.0, 4.5, 2.8, and 3.75% per year over the period 1965–1972. Capital productivity studies for selected companies within the industry failed to show conclusive trends in the efficiency of capital. No correlation of gross capital and labour productivities was observed.
Precipitation nutrients in the open and under two forests in Minnesota
Authors: Verry Elon S. , Timmons D. R.
Published: December 2007

Concentrations of N, P, K, Ca, Mg, and Na were measured in rain and snow in the open, and in throughfall and stemflow under black spruce and aspen forests in north-central Minnesota. Concentrations of total P in rain and black spruce throughfall were inversely related to storm size. Annual precipitation nutrient inputs to the forest floor were calculated for each site. In general, nutrient contributions from snow were less than 10% of the annual nutrient input from precipitation at each site, and differences in snow nutrient input between sites were minimal. Rainfall nutrient input differed significantly between sites. Rain and snow passing through both forest canopies were enriched with nutrients except inorganic nitrogen. Total annual nutrients added to the forest floor under the black spruce stand averaged 1.7 times that added in the open; the annual amount added under the aspen stand averaged 5.2 times that added in the open.
Survival of coastal and interior Douglas fir seedlings after storage at different temperatures, and effectiveness of cold storage in satisfying chilling requirements
Authors: Driessche R. van den
Published: December 2007

Survival and growth of coastal and interior provenances of 2-0 Douglas fir (Pseudotsugamenziesii (Mirb.) Franco), after storage for 16 weeks at different temperatures, were examined in two experiments. In the first experiment, plants of two coastal and two interior provenances were grown under three sets of environmental conditions. These provided non-hardy, partially hardy, and hardy stock of each provenance for storage at 2, −5, and −9 °C. Survival, after 8 weeks poststorage growth in the greenhouse, showed that no provenances survived storage well in a non-hardy condition, and that coastal provenances only stored well at 2 °C. Even interior provenances did not store well at −9 °C.In the second experiment plants of four coastal and four interior provenances were lifted on 10 November and again on 8 December for storage at 2 and −2 °C. Survival and stem relative growth rate measurements, made after plants had been allowed 8 weeks poststorage growth in the greenhouse, showed that 2 °C was less deleterious than −2 °C, and that coastal provenances were less tolerant of the lower temperature. Plants stored on 10 November showed better survival than those stored on 8 December, and there was no clear relationship between stem hardiness, measured by an electrical conductivity method, and survival after storage.In a third experiment, two coastal provenances of 2-0 Douglas fir were used to compare the effect of cold storage at 2 °C with exposure of heeled-in stock to open nursery conditions in satisfying the chilling requirement for bud flushing. Flushing of previously unchilled stock, which had been cold-stored for 12 weeks, occurred as rapidly as flushing of similar stock heeled-in in the open nursery for the same period.
Simulating southern pine beetle activity for pest management decisions
Authors: Leuschner William A. , Matney Thomas G. , Burkhart Harold E.
Published: December 2007

A rudimentary simulator was developed to estimate southern pine beetle (Dendroctonusfrontalis Zimm.) timber mortality damages in future years over large geographical areas in the southern U.S.A. The simulator uses basic data such as monthly mean number of spots, frequency distributions of diameter and number of trees per beetle spot, and certain marketing data. The simulator provides mortality volume and discounted value estimates. Damage reduction patterns for proposed management programs can also be included to calculate program benefits for use in benefit-cost analyses.
Comparison of selected Douglas-fir seed sources for cambial and leader growth patterns in four western Oregon environments
Authors: Emmingham William H.
Published: December 2007

The leader and cambial growth of sapling Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) from both inland and coastal varieties followed a definite pattern in four western Oregon environments. Generally, buds became active first and cambial growth became active soon after. Leader growth stopped in August, long before cambial growth, which continued into October. Phenology, total seasonal growth, and growth pattern for trees from coastal sources from Vancouver Island, B.C., to southern Oregon were more similar than for trees from inland sources from British Columbia to Idaho and Arizona. Most of the differences among populations in one season's growth were related to growth rate rather than growth duration.
An index of photosynthesis for comparing forest sites in western Oregon
Authors: Emmingham William H. , Waring Richard H.
Published: December 2007

An index was developed that takes into account the combined influence of air and soil temperatures, light, and the availability of soil moisture upon photosynthesis by a unit area of fully exposed foliage of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco). The index is derived from a summation of daily estimates of carbon assimilation (milligrams CO2 assimilation per decimeter per day) for an entire year. In a comparison of forest environments in western Oregon the index was correlated to a measure of forest productivity (r2 = 0.99). Furthermore, it suggests that much of the annual carbon fixation occurs during the mild winters characteristic of the region. The ability to assess the effects of frost, soil drought, and other variables separately was valuable in explaining differences between coastal, valley, and mountainous sites.
Starch content of Douglas-fir defoliated by the tussock moth
Authors: Webb Warren L. , Karchesy Joseph J.
Published: December 2007

Defoliation by the Douglas-fir tussock (Orgyiapseudosugata (McDunnough)) moth resulted in a reduction of total tree reserve energy, in the form of starch, proportional to the intensity of defoliation. This reduction was significantly less on a site with faster growing trees.
Leaf dispersal in a pole-size maple stand
Authors: Stone Douglas M.
Published: December 2007

The horizontal distribution of leaf fall was determined for one nonthinned, and two previously released pole-size sugar maple (Acersaccharum Marsh.) trees. Leaf dispersal showed a general north–south pattern reflecting the prevailing winds; most leaves were within 100 ft (30.5 m) of the sample trees. Only about 5% of the total number of leaves remained on the estimated major rooting area. Consequently, fertilizing individual maple trees is likely to have limited long-term value because nutrients contained in the leaves will be distributed throughout the stand.
A MATHEMATICAL STUDY OF A BISTABLE NEMATIC LIQUID CRYSTAL DEVICE
Authors: DA COSTA F. P. , GRINFELD M. , MOTTRAM N. J. , PINTO J. T.
Published: December 2007

We consider a model of a bistable nematic liquid crystal device based on the Ericksen–Leslie theory. The resulting mathematical object is a parabolic PDE with nonlinear dynamic boundary conditions. We analyze well-posedness of the problem and global existence of solutions using the theory developed by Amann. Furthermore, using phase-plane methods, we give an exhaustive description of the steady state solutions and hence of the switching capabilities of the device.
WELL-BALANCED NUMERICAL SCHEMES BASED ON A GENERALIZED HYDROSTATIC RECONSTRUCTION TECHNIQUE
Authors: CASTRO MANUEL J. , PARDO MILANÉS ALBERTO , PARÉS CARLOS
Published: December 2007

The goal of this paper is to generalize the hydrostatic reconstruction technique introduced in Ref. 2 for the shallow water system to more general hyperbolic systems with source term. The key idea is to interpret the numerical scheme obtained with this technique as a path-conservative method, as defined in Ref. 35. This generalization allows us, on the one hand, to construct well-balanced numerical schemes for new problems, as the two-layer shallow water system. On the other hand, we construct numerical schemes for the shallow water system with better well-balanced properties. In particular we obtain a Roe method which solves exactly every stationary solution, and not only those corresponding to water at rest.
APPROXIMATE AND LOW REGULARITY DIRICHLET BOUNDARY CONDITIONS IN THE GENERALIZED FINITE ELEMENT METHOD
Authors: BABUŠKA IVO , NISTOR VICTOR , TARFULEA NICOLAE
Published: December 2007

We propose a method for treating Dirichlet boundary conditions for the Laplacian in the framework of the Generalized Finite Element Method (GFEM). A particular interest is taken in boundary data with low regularity (possibly a distribution). Our method is based on using approximate Dirichlet boundary conditions and polynomial approximations of the boundary. The sequence of GFEM-spaces consists of nonzero boundary value functions, and hence it does not conform to one of the basic Finite Element Method (FEM) conditions. We obtain quasi-optimal rates of convergence for the sequence of GFEM approximations of the exact solution. We also extend our results to the inhomogeneous Dirichlet boundary value problem, including the case when the boundary data has low regularity (i.e. is a distribution). Finally, we indicate an effective technique for constructing sequences of GFEM-spaces satisfying our assumptions by using polynomial approximations of the boundary.
Prebiotic oligosaccharides and the enterohepatic circulation of bile salts in rats
Authors: van Meer Hester , Boehm Gunther , Stellaard Frans , Vriesema Aldwin , Knol Jan , Havinga Rick , Sauer Pieter J. , Verkade Henkjan J.
Published: December 2007

Human milk contains prebiotic oligosaccharides, which stimulate the growth of intestinal bifidobacteria and lactobacilli. It is unclear whether the prebiotic capacity of human milk contributes to the larger bile salt pool size and the more efficient fat absorption in infants fed human milk compared with formula. We determined the effect of prebiotic oligosaccharides on bile salt metabolism in rats. Rats were fed a control diet or an isocaloric diet containing a mixture of galactooligosaccharides (GOS), long-chain fructooligosaccharides (lcFOS), and acidified oligosaccharides (AOS) for 3 wk. We determined synthesis rate, pool size, and fractional turnover rate (FTR) of the primary bile salt cholate by using stable isotope dilution methodology. We quantified bile flow and biliary bile salt secretion rates through bile cannulation. Prebiotic intervention resulted in significant changes in fecal and colonic flora: the proportion of lactobacilli increased 344% ( P < 0.01) in colon content and 139% ( P < 0.01) in feces compared with the control group. The number of bifidobacteria also increased 366% ( P < 0.01) in colon content and 282% in feces after the prebiotic treatment. Furthermore, pH in both colon and feces decreased significantly with 1.0 and 0.5 pH point, respectively. However, despite this alteration of intestinal bacterial flora, no significant effect on relevant parameters of bile salt metabolism and cholate kinetics was found. The present data in rats do not support the hypothesis that prebiotics naturally present in human milk contribute to a larger bile salt pool size or altered bile salt pool kinetics.
Dual purinergic synaptic transmission in the human enteric nervous system
Authors: Wunderlich J. E. , Needleman B. J. , Chen Z. , Yu J. G. , Wang Y. , Grants I. , Mikami D. J. , Melvin W. S. , Cooke H. J. , Christofi F. L.
Published: December 2007

Based on findings in rodents, we sought to test the hypothesis that purinergic modulation of synaptic transmission occurs in the human intestine. Time series analysis of intraneuronal free Ca2+levels in submucosal plexus (SMP) from Roux-en-Y specimens was done using Zeiss LSM laser-scanning confocal fluo-4 AM Ca2+imaging. A 3-s fiber tract stimulation (FTS) was used to elicit a synaptic Ca2+response. Short-circuit current ( Isc= chloride secretion) was recorded in mucosa-SMP in flux chambers. A distension reflex or electrical field stimulation was used to study Iscresponses. Ca2+imaging was done in 1,222 neurons responding to high-K+depolarization from 61 surgical cases. FTS evoked synaptic Ca2+responses in 62% of recorded neurons. FTS caused frequency-dependent Ca2+responses (0.1–100 Hz). FTS Ca2+responses were inhibited by Ω-conotoxin (70%), hexamethonium (50%), TTX, high Mg2+/low Ca2+(≤100%), or capsaicin (25%). A P2Y1receptor (P2Y1R) antagonist, MRS-2179 or PLC inhibitor U-73122, blocked FTS responses (75–90%). P2Y1R-immunoreactivity occurred in 39% of vasoactive intestinal peptide-positive neurons. The selective adenosine A3receptor (AdoA3R) agonist 2-chloro- N6-(3-iodobenzyl)adenosine-5′- N-methylcarboxamide (2-Cl-IBMECA) caused concentration- and frequency-dependent inhibition of FTS Ca2+responses (IC50= 8.5 × 10−8M). The AdoA3R antagonist MRS-1220 augmented such Ca2+responses; 2-Cl-IBMECA competed with MRS-1220. Knockdown of AdoA1R with 8-cyclopentyl-3- N-(3-{[3-(4-fluorosulphonyl)benzoyl]-oxy}-propyl)-1- N-propyl-xanthine did not prevent 2-Cl-IBMECA effects. MRS-1220 caused 31% augmentation of TTX-sensitive distension Iscresponses. The SMP from Roux-en-Y patients is a suitable model to study synaptic transmission in human enteric nervous system (huENS). The P2Y1/Gαq/PLC/inositol 1,3,5-trisphosphate/Ca2+signaling pathway, N-type Ca2+channels, nicotinic receptors, and extrinsic nerves contribute to neurotransmission in huENS. Inhibitory AdoA3R inhibit nucleotide or cholinergic transmission in the huENS.
Atherosclerotic plaque imaging using phase-contrast X-ray computed tomography
Authors: Shinohara Masakazu , Yamashita Tomoya , Tawa Hideto , Takeda Masafumi , Sasaki Naoto , Takaya Tomofumi , Toh Ryuji , Takeuchi Akihisa , Ohigashi Takuji , Shinohara Kunio , Kawashima Seinosuke , Yokoyama Mitsuhiro , Hirata Ken-ichi , Momose Atsushi
Published: December 2007

Reliable, noninvasive imaging modalities to characterize plaque components are clinically desirable for detecting unstable coronary plaques, which cause acute coronary syndrome. Although recent clinical developments in computed tomography (CT) have enabled the visualization of luminal narrowing and calcified plaques in coronary arteries, the identification of noncalcified plaque components remains difficult. Phase-contrast X-ray CT imaging has great potentials to reveal the structures inside biological soft tissues, because its sensitivity to light elements is almost 1,000 times greater than that of absorption-contrast X-ray imaging. Moreover, a specific mass density of tissue can be estimated using phase-contrast X-ray CT. Ex vivo phase-contrast X-ray CT was performed using a synchrotron radiation source (SPring-8, Japan) to investigate atherosclerotic plaque components of apolipoprotein E-deficient mice. Samples were also histologically analyzed. Phase-contrast X-ray CT at a spatial resolution of 10–20 μm revealed atherosclerotic plaque components easily, and thin fibrous caps were detected. The specific mass densities of these plaque components were quantitatively estimated. The mass density of lipid area was significantly lower (1.011 ± 0.001766 g/ml) than that of smooth muscle area or collagen area (1.057 ± 0.001407 and 1.080 ± 0.001794 g/ml, respectively). Moreover, the three-dimensional assessment of plaques could provide their anatomical information. Phase-contrast X-ray CT can estimate the tissue mass density of atherosclerotic plaques and detect lipid-rich areas. It can be a promising noninvasive technique for the investigation of plaque components and detection of unstable coronary plaques.
Lung epithelial injury markers are not influenced by use of lower tidal volumes during elective surgery in patients without preexisting lung injury
Authors: Determann Rogier M. , Wolthuis Esther K. , Choi Goda , Bresser Paul , Bernard Alfred , Lutter Rene , Schultz Marcus J.
Published: December 2007

Clara cell protein levels are elevated in plasma of individuals with mild or subclinical lung injury. We studied the influence of two mechanical ventilation strategies on local and systemic levels of Clara cell protein (CC16) and compared them with levels of soluble receptor for advanced glycation end products (sRAGE) and surfactant proteins (SP)-A and -D in patients undergoing elective surgery. Saved samples from a previously reported investigation were used for the study. Forty patients planned for elective surgery were randomized to mechanical ventilation with either a conventional tidal volume (VT) of 12 ml/kg without positive end-expiratory pressure (PEEP) or low VT of 6 ml/kg and 10 cmH2O PEEP. Plasma and bronchoalveolar lavage fluid (BALF) was collected directly after intubation and after 5 h of mechanical ventilation. While systemic levels of SP-A and SP-D remained unchanged, systemic levels of CC16 and sRAGE increased significantly in both groups after 5 h ( P < 0.001 for both). BALF levels of SP-A, SP-D, CC16, and sRAGE remained unaffected. No differences were found between the two mechanical ventilation strategies regarding any of the measured biological markers. In conclusion, systemic levels of CC16 and sRAGE rise after 5 h in patients receiving mechanical ventilation for elective surgery. Mechanical ventilation with lower tidal volumes and PEEP did not have a different effect on levels of biomarkers of lung epithelial injury compared with conventional mechanical ventilation.
Can exercise modulate the maturation of functionally different immature tendons in the horse?
Authors: Kasashima Y. , Takahashi T. , Birch H. L. , Smith R. K. W. , Goodship A. E.
Published: December 2007

Tendons can be considered in two functional groups, those contributing to energetics of locomotion and those acting solely to position the limb. The energy-storing tendons in both human and equine athletes have a high frequency of injury with similar pathophysiology. In previous studies, high-intensity exercise appears to induce a disruption of the matrix rather than functional adaptation in adults. Here we explore the hypothesis that the introduction of controlled exercise during growth would result in an adaptive response without deleterious effects. Young horses were given a controlled exercise program similar to that previously shown to induce matrix changes in energy-storing tendons of skeletally mature animals. The tendons were assessed in relation to mechanical properties, molecular composition, and morphology. Results showed a significant increase in cartilage oligomeric matrix protein (COMP) in the positional tendon but not in the energy-storing tendon. Other matrix properties and mechanical properties were not significantly changed. While the imposition of high-strain-rate exercise in immature horses failed to augment the development of the energy-storing tendon over and above that induced by normal pasture exercise, it did not induce deleterious changes, supporting an earlier introduction of athletic training in horses.