bluuebunny/crossref_metadata_2025 huggingface dataset:
A LysR-Type Transcriptional Regulator in
Burkholderia cenocepacia
Influences Colony Morphology and Virulence
Authors: Bernier Steve P. , Nguyen David T. , Sokol Pamela A.
Published: October 2007

Burkholderia cenocepacia
strain K56-2 typically has rough colony morphology on agar medium; however, shiny colony variants (shv) can appear spontaneously. These shv all had a minimum of 50% reduction in biomass formation and were generally avirulent in an alfalfa seedling infection model. Three shv—K56-2 S15, K56-2 S76, and K56-2 S86—were analyzed for virulence in a chronic agar bead model of respiratory infection and, although all shv were able to establish chronic infection, they produced significantly less lung histopathology than the rough K56-2. Transmission electron microscopy revealed that an extracellular matrix surrounding bacterial cells was absent or reduced in the shv compared to the rough wild type. Transposon mutagenesis was performed on the rough wild-type strain and a mutant with an insertion upstream of ORF BCAS0225, coding for a putative LysR-type regulator, exhibited shiny colony morphology, reduced biofilm production, increased
N
-acyl homoserine lactone production, and avirulence in alfalfa. The rough parental colony morphotype, biofilm formation, and virulence in alfalfa were restored by providing BCAS0225 in
trans
in the BCAS0225::pGSVTp-
luxCDABF
mutant. Introduction of BCAS0225 restored the rough morphotype in several shv which were determined to have spontaneous mutations in this gene. In the present study, we show that the conversion from rough wild type to shv in
B. cenocepacia
correlates with reduced biofilm formation and virulence, and we determined that BCAS0225 is one gene involved in the regulation of these phenotypes.
Use of a Genetically Engineered Strain To Evaluate the Pathogenic Potential of Yeast Cell and Filamentous Forms duringCandida albicansSystemic Infection in Immunodeficient Mice
Authors: Saville Stephen P. , Lazzell Anna L. , Chaturvedi Ashok K. , Monteagudo Carlos , Lopez-Ribot Jose L.
Published: October 2007

The pathogenesis ofCandida albicanssystemic infection is complex and results from the balance between its intrinsic virulence attributes and the host immune responses. Morphogenetic transitions between yeast cell and filamentous forms are considered one of the main virulence attributes inC. albicans. We have examined the pathogenesis of a genetically engineeredC. albicansstrain in which morphogenetic conversions can be externally manipulated in immunodeficient mice; these included B-cell deficient, nude (T cell deficient), SCID (lacking both functional T and B cells), and DBA/2N (C5 deficient with impaired neutrophil activity) mice. We also tested mice severely immunosuppressed by cyclophosphamide-cortisone acetate treatment. Mice with specific immune defects were able to survive an infection by yeast cells but not filamentous forms. However, yeast cells displayed a pathogenic effect leading to lethality in the severely immunosuppressed mice.
Surfactant-Associated Protein A Provides Critical Immunoprotection in Neonatal Mice
Authors: George Caroline L. S. , Goss Kelli L. , Meyerholz David K. , Lamb Fred S. , Snyder Jeanne M.
Published: October 2007

The collectins surfactant-associated protein A (SP-A) and SP-D are components of innate immunity that are present before birth. Both proteins bind pathogens and assist in clearing infection. The significance of SP-A and SP-D as components of the neonatal immune system has not been investigated. To determine the role of SP-A and SP-D in neonatal immunity, wild-type, SP-A null, and SP-D null mice were bred in a bacterium-laden environment (corn dust bedding) or in a semisterile environment (cellulose fiber bedding). When reared in the corn dust bedding, SP-A null pups had significant mortality (P< 0.001) compared to both wild-type and SP-D null pups exposed to the same environment. The mortality of the SP-A null pups was associated with significant gastrointestinal tract pathology but little lung pathology. Moribund SP-A null newborn mice exhibitedBacillussp. andEnterococcussp. peritonitis. When the mother or newborn produced SP-A, newborn survival was significantly improved (P< 0.05) compared to the results when there was a complete absence of SP-A in both the mother and the pup. Significant sources of SP-A likely to protect a newborn include the neonatal lung and gastrointestinal tract but not the lactating mammary tissue of the mother. Furthermore, exogenous SP-A delivered by mouth to newborn SP-A null pups with SP-A null mothers improved newborn survival in the corn dust environment. Therefore, a lack of SP-D did not affect newborn survival, while SP-A produced by either the mother or the pup or oral exogenous SP-A significantly reduced newborn mortality associated with environmentally induced infection in SP-A null newborns.
Toll-Like Receptor 2-Mediated Interleukin-8 Expression in Gingival Epithelial Cells by the
Tannerella forsythia
Leucine-Rich Repeat Protein BspA
Authors: Onishi Shinsuke , Honma Kiyonobu , Liang Shuang , Stathopoulou Panagiota , Kinane Denis , Hajishengallis George , Sharma Ashu
Published: October 2007

Tannerella forsythia
is a gram-negative anaerobe strongly associated with chronic human periodontitis. This bacterium expresses a cell surface-associated and secreted protein, designated BspA, which has been recognized as an important virulence factor. The BspA protein belongs to the leucine-rich repeat (LRR) and bacterial immunoglobulin-like protein families. BspA is, moreover, a multifunctional protein which interacts with a variety of host cells, including monocytes which appear to respond to BspA through Toll-like receptor (TLR) signaling. Since gingival epithelium forms a barrier against periodontal pathogens, this study was undertaken to determine if gingival epithelial cells respond to BspA challenge and if TLRs play any role in BspA recognition. This study was also directed towards identifying the BspA domains responsible for cellular activation. We provide direct evidence for BspA binding to TLR2 and demonstrate that the release of the chemokine interleukin-8 from human gingival epithelial cells by BspA is TLR2 dependent. Furthermore, the LRR domain of BspA is involved in activation of TLR2, while TLR1 serves as a signaling partner. Thus, our findings suggest that BspA is an important modulator of host innate immune responses through activation of TLR2 in cooperation with TLR1.
Oral Vaccination withSalmonella entericaas a Cruzipain-DNA Delivery System Confers Protective Immunity againstTrypanosoma cruzi
Authors: Cazorla Silvia I. , Becker Pablo D. , Frank Fernanda M. , Ebensen Thomas , Sartori María J. , Corral Ricardo S. , Malchiodi Emilio L. , Guzmán Carlos A.
Published: October 2007

To stimulate both local and systemic immune responses againstTrypanosoma cruzi,Salmonella entericaserovar TyphimuriumaroAwas exploited as a DNA delivery system for cruzipain (SCz). In a murine model we compared SCz alone (GI) or coadministered withSalmonellacarrying a plasmid encoding granulocyte-macrophage colony-stimulating factor (GII), as well as protocols in which SCz priming was followed by boosting with recombinant cruzipain (rCz) admixed with either CpG-ODN (GIII) or MALP-2, a synthetic derivative of a macrophage-activating lipopeptide of 2 kDa fromMycoplasma fermentans(GIV). The results showed that protocols that included four oral doses of SCz (GI) elicited mainly a mucosal response characterized by immunoglobulin A (IgA) secretion and proliferation of gut-associated lymphoid tissue cells, with weak systemic responses. In contrast, the protocol that included a boost with rCz plus CpG (GIII) triggered stronger systemic responses in terms of Cz-specific serum IgG titers, splenocyte proliferation, gamma interferon (IFN-γ) secretion, and delayed-type hypersensitivity response. Trypomastigote challenge of vaccinated mice resulted in significantly lower levels of parasitemia compared to controls. Protection was abolished by depletion of either CD4+or CD8+T cells. Parasite control was also evident from the reduction of tissue damage, as revealed by histopathologic studies and serum levels of enzymes that are markers of muscle injury in chronic Chagas' disease (i.e., creatine kinase, aspartate aminotransferase, and lactate dehydrogenase). Enhanced release of IFN-γ and interleukin-2 was observed in GI and GII upon restimulation of splenocytes in the nonparasitic phase of infection. Our results indicate thatSalmonella-mediated delivery of Cz-DNA by itself promotes the elicitation of an immune response that controlsT. cruziinfection, thereby reducing parasite loads and subsequent damage to muscle tissues.
Hybridization among several North American firs. I. Crossability
Authors: Hawley Gary J. , DeHayes Donald H.
Published: October 2007

Controlled pollinations were conducted in spring of 1980, 1981, and 1982 to determine crossability among five species and varieties of Abies in the Balsameae section and white fir (A. concolor (Gord. and Glend.) Lindl.) from section Grandes. Trees representing eastern balsam fir populations (A. balsamea (L.) Mill.), Fraser fir (A. fraseri (Pursh) Poir.), bracted balsam fir (A. balsamea var. phanerolepis Fern.), and white fir were used as female parents and were control pollinated with pollen from two populations each of balsam fir. Fraser fir, and subalpine fir (A. lasiocarpa (Hook.) Nutt.), and one population each of bracted balsam and white firs. Based on viable seed production, eastern balsam × Fraser fir and reciprocals, Fraser × bracted balsam fir and reciprocals, and bracted balsam × subalpine fir were fully crossable. The complete crossability of these taxa suggest that geographic rather than genetic isolation is responsible for their taxonomic separation. Although bracted balsam × balsam fir (Vermont) was fully crossable, the reciprocal cross exhibited partial incompatibility which may be sufficient to maintain the integrity of these two sympatric taxa. Crosses involving white fir and balsam fir from a Minnesota population as male parents yielded a relatively low percentage of viable seed. Those involving white fir probably reflect low intersectional crossability, whereas those with the Minnesota balsam fir population may have been the result of either low pollen viability or low crossability.
Within-tree variation in wood production and wood quality in sycamore (Acerpseudoplatanus): its relation to crown characteristics
Authors: Dodd Richard S.
Published: October 2007

To quantify patterns of wood formation in sycamore (Acerpseudoplatanus L.), the seasonal progress of wood production and structure was followed systematically throughout the outer growth sheath of the main stem and major branches. These data were considered in relation to the profile of leaf dry weight down through the crown in 8- and 12-year-old trees at stages before and after canopy closure, respectively. Mature fibre production was earliest towards the tips of the branches of the midcrown, and spread basipetally along the branches. In the main stem, mature fibre production was earliest at the tip and spread down the tree, taking about 10 days to reach the base of both pre- and post-canopy closure trees. In the stem, later fibre production down the tree was offset by later cessation of fibre maturation basally. Branch data suggested that the pattern of cessation may depend on the branch position, because cessation was latest at the base of the upper branches and at the tip of the lower branches. The maximum rate of fibre production was in the upper stem, several internodes higher than the internode bearing maximum leaf dry weight. Despite this, ring width increased down the stem, presumably as a result of the increased duration of fibre production and increased cell size. Within growth rings, vessel size remained nearly constant before declining sharply towards the end of the ring. Trees with narrower growth rings tended to have more of their ring occupied by declining vessel size suggesting a slight inverse relationship between ring width and specific gravity. Specific gravity increased down the outer growth sheath of the stem, and this increase was associated with systematic trends in fibre and vessel dimensions, together with changes in the relative proportions by area of the different tissues. Although some anatomical characters appeared to vary with the profile of the crown, others appeared to be independent of crown profile.
Light reduction and moisture stress: effects on growth and water relations of western larch seedlings
Authors: Vance Nan C. , Running Steven W.
Published: October 2007

Ten-week-old western larch (Larixoccidentalis Nutt.) seedlings were grown in a greenhouse under 70, 37, and 27% full sunlight from late July to early October. In August, seedlings under each light treatment were repetitively water stressed until predawn leaf water potential (Bψ1) reached one of three levels: no stress (> −0.4 MPa), moderate stress (−0.7 to −1.0 MPa), and severe stress (−1.5 to −1.8 MPa). Moisture stressing significantly reduced height and diameter of seedlings grown under 70% light. Light reduction reduced shoot and root biomass accumulation. A positive linear relation was found between root dry weight and light intensity. The largest seedlings (on a weight basis) received the highest light, were unstressed, and had the lowest shoot/root ratios. Terminal bud set was not affected by light reduction or moisture stressing but occurred under a 14-h photoperiod and reduced nighttime temperatures. Stressed and shaded seedlings had significantly reduced diurnal K1 and stress-cycled seedlings showed an adjustment to stressing. The K1 of unstressed seedlings was correlated with humidity deficit (ABHD), and K1 of stressed seedlings, with Bψ1, and ABHD. Maximum K1 declined with decreasing Bψ1, but not to a level indicating complete stomatal closure.
Comparison of a model-based sampling strategy with point–Poisson sampling on a timber management area in the Arapahoe–Roosevelt National Forest in Colorado
Authors: Wood G. B. , Schreuder H. T. , Brink G. E.
Published: October 2007

Field procedures, incorporating model-based (MB) sampling, were developed to estimate the volume of timber in a 20-ha coniferous forest, in the Arapahoe–Roosevelt National Forest of Colorado. Estimates derived for two point – MB, two point – Poisson (PP), and a large (20%) Poisson sample confirm that point–MB sampling is as efficient as the PP procedure. Point–MB sampling has the advantage that the size of the second-stage sample can be rigidly controlled. It practically guarantees a good sample, whereas poor samples occasionally are selected with PP sampling.
Étude de la production totale: exemple d'une table pour le sapin baumier
Authors: Zarnovican R. , Vézina P.-E.
Published: October 2007

The present work analyzes the principal mensurational components of 52 research stands located in the lac Joffre area. A total wood yield table is methodologically established and proposed for even-aged, monospecific balsam fir (Abiesbalsamea (L.) Mill.) stands forming a single growth series.
Wound-induced changes of resin acid concentrations in living bark of Scots pine seedlings
Authors: Gref Rolf , Ericsson Anders
Published: October 2007

One-year-old Pinussylvestris (L.) seedlings were wounded at the stem base by stripping off stem bark pieces of approximately 10 mm in length and covering about 50% of the stem circumference. The seedlings were thereafter planted out in the field or in a climate chamber. The field experiment was repeated on four different planting dates. Wounded and control seedlings were successively harvested for gas chromatographic determination of changes in resin acid concentrations of the bark surrounding the wounded area. Independent of planting date, wounded seedlings were found to have higher concentrations of total resin acids than corresponding controls. The most important quantitative changes in resin acids were observed for isopimaric, levopimaric + palustric, dehydroabietie, abietic, and neoabietic acid. In wounded seedlings the concentration of dehydroabietic acid showed the most significant increase, both in the field and in climate chamber experiments. This increase was rapid and appeared within 1 week in the field and within 3 days in the climate chamber. The other resin acids identified showed a somewhat similar variation pattern, but the differences were not as distinct as for dehydroabietic acid. These wound-induced rapid changes in resin acid concentrations could be important for resistance to pathogens.
Market structure and economic performance of forest products industry in Ontario and Canada
Authors: Nautiyal J. C. , Singh B. K. , Menezes O.
Published: October 2007

Market structure for three major groups of Ontario and Canadian forest products industry was examined over the years 1975–1980 and 1965–1980, respectively, in terms of domestic seller concentration ratios. The analysis indicated that forest industries in Ontario are more or less a homogeneous part of those in Canada. However, patterns of change in concentration over time in both jurisdictions are different. Lumber industry in Ontario as well as in Canada, though not very competitive, is certainly unconcentrated. The pulp and paper industry, on the other hand, is mildly oligopolistic in both jurisdictions. The relatively small veneer and plywood industry is mildly oligopolistic in Ontario, but strongly so in Canada. Profitability of forest industries in Canada is positively and significantly related to the proportion of output exported and to the degree of domestic seller concentration. This degree of concentration, in turn, seems to be largely determined by the presence of economies of scale.
Approaches to determining monetary welfare change measures
Authors: Johansson Per-Olov
Published: October 2007

National forest lands are often managed in a way which departs from the classical Faustmann rotation criterion. This is true, at least in part, because national forest lands are also managed for nontimber purposes such as recreation, wilderness, and wildlife. This paper derives cutting rules to be used in situations where forest uses other than timber production are affected by the design of the cutting program (e.g., timber age, methods of cutting, and replanting). Both "external effects" in consumption and in production are considered. The paper also contains a discussion of whether forest owners should be induced ("bribed") or forced through regulations to behave in a socially optimal way when there are multiple uses of forest land.
Relationships between balsam fir mortality caused by the spruce budworm and stand, site, and soil variables in Michigan's Upper Peninsula
Authors: Lynch Ann M. , Witter John A.
Published: October 2007

The association of various stand, site, and soil variables with impact of the spruce budworm, Choristoneurafumiferana (Clemens), on balsam fir, Abiesbalsamea (L.) Mill., was examined in the Hiawatha and Ottawa National Forests of Michigan's Upper Peninsula. Geographic differences in impact were due, at least in part, to differences in the duration of the budworm outbreak. Impact was extremely variable between stands. Linear relations observed between impact variables and stand, site, and soil variables were weak. The quantity of balsam fir in the stand (basal area per hectare or proportion of stocking) was positively correlated with dead basal area per hectare but not with percent basal area mortality. Increased impact was associated with increased quantities of white pine (Pinusstrobus L.), northern white-cedar (Thujaoccidentalis L.), eastern hemlock (Tsugacanadensis (L.) Carr.), sugar maple (Acersaccharum L.), and red maple (Acerrubrum L.) in one or both of the National Forests. Drainage and soil moisture appeared to play a role in determining the amount of spruce budworm impact in individual stands. Principal components extracted from the stand data accounted for variability between different stand types. However, the between-stand variability in impact did not coincide with the between-stand-type variability described by the components.
Bioassay of forest floor phosphorus supply for plant growth
Authors: Cleve K. Van , Harrison F.
Published: October 2007

This paper considers the extent to which phosphorus (P) supply for plant use is controlled by the chemical quality of forest floor organic matter, independent of climate. Using plant bioassays, forest floor materials from representative examples of each of the major forest types in interior Alaska were examined for nutrient supplying power. The work supports conclusions reached in earlier studies which indicated that black spruce forest floors were highly nutrient limited compared with those of other interior Alaska forest types. In addition, floodplain white spruce forests may experience marked P deficiency because of dilution of the element by periodic siltation. Potential phosphorus supply for seedling growth was best described by P concentration of the rooting medium. The supply also was related to the concentrations of lignin and tannin which control forest floor decomposition and recycling of P within the microbial population.
The promotion of flowering in large field-grown Sitka spruce by girdling and stem injections of gibberellin A4/7
Authors: Philipson J. J.
Published: October 2007

Mature 14-year-old grafted Piceasitchensis (Bong.) Carr. which were field grown and 6 m tall were given stem injections of gibberellin A4/7 (GA4/7) alone and in combination with girdling. The GA4/7 was applied twice, at 100 or 250 mg per application. GA4/7 alone produced a large and significant stimulation of the numbers of both pollen and seed cones, with means of about 200 pollen and 90 seed cones per tree, and 90% of the clones flowering; both levels of GA4/7 application stimulated flowering to approximately the same extent. The girdling treatment enhanced flowering when environmental conditions facilitated light flowering of the controls, and also increased the response to 100 mg GA4/7. The stimulation of flowering was carried over into the 2nd year after treatment, but only when both girdling and GA4/7 had been applied together.
Effects of fenitrothion and adjuvants on the decomposition rate of white spruce foliage in litter bags on the forest floor
Authors: Eidt D. C. , Weaver C. A. A.
Published: October 2007

Fenitrothion in oil and water-based formulations at the conventional aerial emission rate and 10 times that rate, and adjuvants alone at 10 times the aerial emission rate, had no effect on the decomposition rate of white spruce foliage, as indicated by weight loss.
Effect of crown position on foliar concentrations of 11 elements in Acersaccharum and Betulaalleghaniensis trees on a till soil
Authors: Morrison I. K.
Published: October 2007

Concentrations of N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, and Na were examined in whole leaves collected in August 1981 from specified positions within the crowns of 15 Acersaccharum Marsh, and 10 Betulaalleghaniensis Britton trees growing in closed forest on a Precambrian-derived till soil in northern Ontario. Concentrations of K, Ca, Mg, Fe, Zn, and Na were significantly higher in lower crown leaves of A. saccharum, and Ca was significantly higher in lower crown leaves of B. alleghaniensis, but in other elements there were no significant differences attributable to crown position. There was a tendency for element concentrations to be higher at all crown positions in intermediate as opposed to codominant trees; however, differences were not significant or were weakly significant at best. Tree-to-tree variation was less in mid- and lower-crown, as opposed to upper-crown, foliage. Generally, for both species, to bring standard errors to within ± 10% of the group mean, about 30 trees per stand should be sampled if analyses are restricted to N, P, K, Ca, Mg, and 40–70 trees per stand should be sampled if trace elements such as Mn are to be included.
Needle water potential and soil-to-foliage flow resistance during soil drying: a comparison of Douglas-fir, western hemlock, and mountain hemlock
Authors: Ballard T. M. , Dosskey M. G.
Published: October 2007

Needle water potential in western and mountain hemlock falls as the soil dries, but under our experimental conditions, it remained stable in Douglas-fir. Resistance to water flow from soil to foliage is higher for the hemlocks and increases more steeply as the soil dries. These findings physically account for the observation that water uptake is reduced relatively more for the hemlocks than for Douglas-fir, as soil water potential declines.
Optimization of silvicultural investment for several types of stand projection systems
Authors: Brodie J. Douglas , Haight Robert G.
Published: October 2007

Dynamic programming using a forward recursion has been found to be a flexible tool for optimizing the investment decisions involved in thinning- and rotation-age determination for several types of even-age forest growth models used by managers in various regions of the United States. This tool is also adaptable to additional decisions including planting density, pre-commercial thinning density, fertilization timing and intensity, and thinning type. Computational methods and limitations to integrating these additional decisions into several types of growth models are explained and reviewed.
Sampling with partial replacement with different types of samples
Authors: Cunia T. , Kyaw U Shwe
Published: October 2007

One of the implicit assumptions of the sampling with partial replacement (SPR) technique is that the sample units are of the same size, shape, and structure. When this assumption is not satisfied, a simple transformation of the sample size values may sometimes be sufficient to make the SPR formulae applicable. These transformations may be determined from past studies with similar inventory data or from additional field measurements taken during the current inventory.
Disturbance and community organization in the boreal forest/Perturbation et organisation communautaire dans la forêt boréale
Authors: Johnson E. A.
Published: October 2007

not available
Natural disturbance and gap phase dynamics in southern Appalachian spruce–fir forests
Authors: White Peter S. , MacKenzie Mark D. , Busing Richard T.
Published: October 2007

Spatially small canopy gaps dominated the natural disturbance regime of old-growth spruce–fir forests in the Great Smoky Mountains, North Carolina and Tennessee. New gaps ≤200 m2 in size were formed with a frequency of 0.006 to 0.009/year and the 1- to 10-year age class of these gaps covered an estimated 6 to 17% of the study area (depending on calculation method). Sixty canopy gaps sampled on a 7-ha intensive study site ranged in size from 15 to 150 m2. Although tree replacement patterns in these gaps were unpredictable from gap size and age, the gap event was important in species interactions. The three canopy dominants, Abiesfraseri (Pursh) Poir., Picearubens Sarg., and Betulalutea Michx.f., had unique suites of life history traits. Abies reached high understory densities, but had the highest canopy turnover rate of the three species. Betula was scarce in the understory, but had a crown expansion rate in gaps eight times that of the two conifers. Picea was the longest lived species and appeared to have the best survivorship. Tree replacement models based on advanced regeneration led to the prediction that Abies canopy density would increase and Betula canopy density would decrease, while models based on gap inventories led to opposite conclusions. Data from direct observation of the gap capture process supported the hypothesis that this old-growth stand was near compositional equilibrium and underscored the importance of disturbance effects in community organization.
Dynamics of the boreal forests of the Laurentian Highlands, Canada
Authors: Cogbill Charles V.
Published: October 2007

Analyses of species composition and tree increment cores from 145 stands in central Québec were used to determine the forest history and stand dynamics. Windspread fires, possibly synchronous, burned across central Québec in at least three periods of record (1661–1663, 1779–1791, 1869–1871). The average fire rotation (time interval between natural fires burning the equivalent of a large area) for spruce – feather moss forests was approximately 130 years, and 70 years in either deciduous or jack pine forests. The traditional succession concept of continual recruitment leading to an all-aged forest was not evident in these forests. About 70% of the overstory trees were established in the first 30 years after fire disturbance, with little recruitment after this time. These initial trees dominate the canopy for up to 250 years with mortality becoming prominent after 130 years. The short average time between disturbances precludes the probable degeneration into old shrub-filled stands typical of old age.
Forest turnover and the dynamics of bole wood litter in subalpine balsam fir forest
Authors: Lang Gerald E.
Published: October 2007

A chronosequence of three stands of balsam fir was sampled in 1974 and 1982; during these 8 years, recruitment was absent so mortality alone accounted for an 18–30% decrease in live tree density. In a mature 78-year-old stand, the mass of bole wood on the forest floor was 1.4 kg•m−2 compared with an estimated aboveground live and dead bole biomass of 17.2 kg•m−2. During 5 years of repetitive sampling, annual bole input to the forest floor was episodic and variable in time and space, ranging from 3 to 365 g•m−2•year−1. A mass balance model was used to characterize the changes in wood litter on the forest floor. If most of the live trees die within a short period of time, bole input would occur in a pulse event and cause a peak in wood litter mass, which would then decline over time (and with stand maturation) as decomposition prevails. The assumption of steady-state conditions for wood litter is not valid; rather the mass of wood litter will wax and wane through time. Over a landscape, spatial patterns in the abundance of wood litter reflect a stand's history; old mature stands would have little wood litter while young regenerating stands would have large amounts. A maximum value for wood litter would be found in a stand located immediately behind a fir wave. Natural disturbances from wind and avalanches lead to contrasting patterns with high and low wood litter values, respectively. About 41% of forest turnover in the balsam fir zone is initiated from natural disturbance and fir waves.
Postfire regeneration of plant and soil organic pools in a Piceamariana–Cladoniastellaris ecosystem
Authors: Auclair Allan N. D.
Published: October 2007

Postfire recovery of biomass and soil organic pools was measured in a sequence of 10 subarctic lichen woodlands aged from 0 to 140 years. Less than one-tenth of total live biomass combusted at the time of burning. Aboveground biomass combustion of species ranged from nil to over 90% depending on plant stature. Although no trees or lichen survived, shrub mortality (6%) was minor. Developmental phases similar to those in northern hardwood forest were apparent. Reorganization was dominated by shrubs over the first three decades. Aggradation resulted in a fourfold increase in total biomass; it was then followed by a 14% decrease occurring at transition (110–140 years postfire). Breakdown of the burnt lichen mat was rapid (1500 kg•ha−1•year−1) compared with the disintegration of dead wood. Of an initial 40 000 kg•ha−1 in dead boles and branches, 15 000 kg•ha−1 remained 110 years later. Little change in soil humus mass occurred during fire and postfire. Total live and dead organic mass remained relatively constant over the 140 years of recovery. However, the live/dead ratio of organic mass showed a gradual but consistent increase.
Disturbance: the process and the response. An epilogue
Authors: Johnson E. A.
Published: October 2007

One gap in our understanding of disturbances became evident during this symposium and in the discussions before and after: How did the disturbances work and how exactly did they affect plants? In this epilogue I consider why the traditional study of succession by describing developmental sequences has led to such a slow formulation of the coupling of disturbance processes to ecological responses. A conceptual framework is also suggested for the coupling of process and response.
Methods for estimating seedbed receptivity and for predicting seedling stocking and density in broadcast seeding
Authors: Groot A.
Published: October 2007

Two aposteriori and three multiple regression techniques were used to estimate the receptivity of 20 seedbed types in two trials of black spruce (Piceamariana (Mill.) B.S.P.) broadcast seeding in northern Ontario. None of the methods was a satisfactory substitute for experimental determination of receptivity by means of seed spots. Receptivity varied within seedbed types, and the β probability density function described the variability reasonably well. In the broadcast seeding trials, three probabilistic models were used to predict regeneration stocking from seeding rate, seedbed area, and seedbed receptivity. The model that took into account within-seedbed variability predicted seedling stocking with the lowest bias (−0.03).
The influence of species composition on the growth of individual red oaks in mixed stands in southern New England
Authors: Kittredge Jr. David B.
Published: October 2007

Research in 40- to 60-year-old even-aged mixed hardwood stands in southern New England suggests a stratified canopy structure by species, with red oak crowns occupying the uppermost canopy stratum. The basal area growth of individual red oak trees with crowns in this uppermost canopy stratum is negatively related to the basal area of neighboring oaks with crowns in the same stratum. The total basal area of neighboring trees with crowns in this stratum has no effect on individual oak growth. Similarly, the basal area of trees in lower strata has no significant effect on the growth of oaks with crowns in the uppermost canopy stratum. Crown width of individual oaks is negatively related to the basal area of neighboring oaks with crowns in the uppermost canopy stratum. Also, both the total foliar biomass per tree and the efficiency of that foliage in producing basal area increment are negatively related to the quantity of surrounding oaks with crowns in the uppermost canopy stratum. These results imply that basal area increment of individual red oaks in the overstory depends on the species composition of the mixture (i.e., the proportion of red oaks in the mixture) and the resulting competition for growing space in the canopy.
A local roundwood supply and price assessment model
Authors: Clements Stephen E. , Leuschner William A. , Hoganson Howard , Wisdom Harold W.
Published: October 2007

Models to analyze subregional forest products markets are needed as policy tools. This paper develops a model that can be used for such analyses. It is a simulation model that predicts the economic stock supply of primary products on the basis of estimates of product demands and production costs. Two market levels are considered: one for primary wood products and one for stumpage. The model recognizes quantity and price determinants for roundwood delivered f.o.b. the mill. These determinants include differential harvesting and transportation costs, complementary–competitive relationships between primary products, and landowner response to price. Thus, what is sometimes called "economic timber supply" by practitioners is determined. Components of the model are described and an application is presented.
Growth habits and crown architecture of Betulapubescens Ehrh. of seed and sprout origin
Authors: Kauppi A. , Kiviniitty M. , Ferm A.
Published: October 2007

Patterns of height increment and ramification in Betulapubescens Ehrh. of sprout and seed origin were studied at Kannus (63°53′ N) during the first few growing seasons, 1982–1985, employing trees of various ages (0–15 years). Sprouts developed very much more rapidly than seedlings during the first three seasons, as a consequence of the free growth pattern and associated pronounced growth flushes. Their annual height increment declined somewhat after a few years, however, whereas that of trees of seed origin remained constant or increased slightly. The mode of height growth in birches over 10 years of age appeared to approach the short-duration growth model. Branches of sprouts also grew more than those of seedlings, in the first few growing seasons, with distinct differences in branching pattern visible between the two tree forms, and also between sprouts originating from buds located above and below ground. Young sprouts used practically all buds to form branches and short shoots, giving them a bush-like appearance. In contrast, most axillary buds on seedlings remained dormant and the individuals adopted an arboreal mode of growth at an early stage. The less branched appearance of older trees of seed origin was also due in part to the death of a higher proportion of buds and branches.
Responses of red spruce seedlings to changes in soil aluminum in six amended forest soil horizons
Authors: Joslin J. Devereux , Wolfe Mark H.
Published: October 2007

A greenhouse pot study was conducted to develop response curves for red spruce (Picearubens Sarg.) seedlings to soil aluminum parameters, using soil from six diverse forest soil horizons. Soil Al levels were manipulated by varying pH through acidification (with HCl or HCl and CaSO4), liming (with Ca(OH)2), and control treatments. Treatments significantly (p < 0.05) altered soil pH (0.01 M CaCl2), 0.01 M SrCl2-extractable Al, and soil solution Al concentrations. Root biomass and foliar biomass were significantly reduced in most acidification treatments, and strong correlations between soil parameters of Al and biomass responses point to Al as the major cause of biomass reductions, especially in the three horizons where the toxicity threshold (approximately 200 μM inorganic monomeric Al) was markedly exceeded. Soil solution levels of inorganic monomeric Al and total Al (R2 = 0.79 and 0.74, respectively) were superior predictors of root biomass compared with the activity of Al3+ in solution (0.61) and 0.01 M SrCl2-extractable Al (0.61). Plant response curves to these soil solution inorganic monomeric Al concentrations are in agreement with those developed in published research on solution culture of red spruce seedlings. Peak soil solution Al concentrations measured in mature red spruce stands approach toxicity thresholds observed in this study.
Volume and mass of decaying logs in an upland old-growth redwood forest
Authors: Bingham Bruce B. , Sawyer Jr. John O.
Published: October 2007

A line intersect technique was used to determine the volume and mass of dead, naturally fallen logs at least 25 cm in diameter and 4 m or more in length over an 80-ha mesic, upland old-growth redwood forest in northwestern California. Each log was identified to species and placed in one of three decay classes: sound logs, moderately decayed logs, and logs in an advanced state of decay. Only logs of redwood (Sequoiasempervirens (D. Don) Endl.), Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), and western hemlock (Tsugaheterophylla (Raf.) Sarg.) met the dimension requirements of sampling. Redwood logs in the middle decay class had the greatest volume (528 m3/ha) and mass (116 t/ha). The total volume and mass of all logs were 957 m3/ha and 200 t/ha, respectively. The total volume and mass of decaying logs in this redwood stand exceeded averages typical of other kinds of low-elevation coniferous forests in the Douglas-fir region.
Maltol protects against infection of lodgepole pine seedlings by western gall rust
Authors: Blenis Peter V. , Wiggins Kathleen L. , Cunningham James E. , Pickard Michael A.
Published: October 2007

Uptake and translocation of maltol into 6-week-old Pinusconforta (Engelm.) var. latifolia seedlings was followed by means of gas chromatography. Maltol concentrations of 6.0–7.3 mg/g seedling dry weight (46–55 μg/seedling) were observed over the first 3 days following a single application of 50 mg maltol/seedling. A split-plot design was used to determine if maltol could reduce seedling infection by Endocronartiumharknessii. Whole plots consisted of two inoculum levels (7 or 30 mg of spores per tray of seedlings) and subplots consisted of four levels of maltol (0, 2, 10, or 40 mg/mL) applied 2 days before inoculation to one-half tray of seedlings at the rate of 5 mL/cavity. The highest concentration consistently and significantly reduced seedling infection relative to the untreated control, although it also caused some phytotoxicity.
Thripscalcaratus Uzel (Thysanoptera: Thripidae), a new pest of basswood trees in the Great Lakes region
Authors: Raffa Kenneth F. , Hall David J.
Published: October 2007

Severe defoliation of basswood trees throughout the Great Lakes region is caused by an introduced thrips, Thripscalcaratus Uzel. This damage had previously been attributed to the native basswood thrips, Sericothripstiliae Hood. The biology and impact of this new pest are poorly understood, and current research is aimed at addressing this problem.
TABLE-DRIVEN CONTEXT-FREE PICTURE GRAMMARS
Authors: BHIKA CHARITA , EWERT SIGRID , SCHWARTZ RYAN , WARUHIU MUTAHI
Published: October 2007

Random context picture grammars (rcpgs) are a method of syntactic picture generation. The productions of such a grammar are context-free, but their application is regulated—permitted or forbidden—by context randomly distributed in the developing picture. In previous work we studied three natural subclasses of rcpgs, namely context-free picture grammars (cfpgs), random permitting context picture grammars (rPcpgs) and random forbidding context picture grammars (rFcpgs). We now introduce the notion of table-driven context-free picture grammars (Tcfpgs), and compare them to the above subclasses. We show that Tcfpgs are more powerful than cfpgs, and that they can generate a picture set (more commonly known as a gallery) that rPcpgs cannot. We present two conditions necessary for a gallery to be generated by a Tcfpg, and use these results to find two galleries that cannot be made by any Tcfpg. The second of these galleries can be generated by an rFcpg. Since it is easily shown that any gallery generated by a Tcfpg can be generated by an rFcpg, we can conclude that Tcfpgs are strictly weaker than rFcpgs.
INTRA-MOLECULAR TEMPLATE-GUIDED RECOMBINATION
Authors: DALEY MARK , DOMARATZKI MICHAEL , MORRIS ALEXIS
Published: October 2007

This paper considers an intra-molecular version of template-guided recombination (TGR), which has been studied in recent papers as an inter-molecular operation. We demonstrate that the intra-molecular TGR operations are distinct from previous intramolecular models for ciliate gene assembly, including the ld and hi operations. We examine the language-theoretic properties of intra-molecular TGR, including closure properties and solutions to language equations.
BOOLEAN FUZZY SETS
Authors: ÉSIK ZOLTÁN , KUICH WERNER
Published: October 2007

Extending the notion of context-free languages and equational sets, we use the approximation theory to define boolean subsets and boolean fuzzy subsets of an algebra. We establish some basic properties of boolean fuzzy sets.
PROGRAMMED GRAMMARS WITH RULE QUEUES
Authors: FERNAU HENNING
Published: October 2007

We generalise the well-known notion of programmed grammars without appearance checking by introducing a buffer that could store sequences of rules, thus not necessarily describing the rule to be selected in the very next step, but rather in some future time.
PARTIAL HALTING IN P SYSTEMS
Authors: FREUND RUDOLF , OSWALD MARION
Published: October 2007

We consider a new variant of the halting condition in P systems, i.e., a computation in a P system is already called halting if no multiset of rules containing a rule from each set of rules assigned to the membranes is applicable anymore, whereas usually a computation is called halting if no rule is applicable anymore in the whole system. This new variant of partial halting is especially investigated for (catalytic) P systems and antiport P systems working in different derivation modes.
P SYSTEMS WITH SINGLE PASSENGER CARRIERS
Authors: GAO YAN , HOOGEBOOM HENDRIK JAN
Published: October 2007

Membrane systems with carriers holding only a single passenger are known to be computationally complete, although this result does not bound the number of membranes and the number of carriers. We show that actually two membranes suffice.
SOLITON AUTOMATA BASED ON TREES
Authors: JÜRGENSEN HELMUT , KRAAK PAULINE
Published: October 2007

Soliton automata are a mathematical model for molecular switching devices. For even the simple case of soliton automata based on trees the behaviour is not known. For example, only two examples of such soliton automata were known the transition monoid of which is not the symmetric group on the set of states; and in these cases the transition monoid is the corresponding alternating group.

We establish new bounds on the number of states of a tree-based soliton automaton and a sufficient condition for when the transition monoid of such a soliton automaton consists only of even permutations of the set of states. We also summarize the results of a systematic enumeration of tree-based soliton automata by which additional exceptions were found, each an alternating group in its natural representation.
SOME REMARKS ON QUANTUM AUTOMATA
Authors: KUDLEK MANFRED
Published: October 2007

A uniform mathematical description of quantum automata as quantum finite automata, quantum linear bounded automata, and quantum Turing machines is introduced, and the existence of such automata under certain circumstances is investigated. Such quantum automata are modelled by isometric rather than unitary operators, reflecting the fact that computation is primarily irreversible in contrast to physical phenomena in the microworld. The global conditions determine the local conditions of the operators.
WHEN CHURCH-ROSSER BECOMES CONTEXT FREE
Authors: KUTRIB MARTIN , MALCHER ANDREAS
Published: October 2007

We investigate the intersection of Church-Rosser languages and (strongly) context-free languages. The intersection is still a proper superset of the deterministic context-free languages as well as of their reversals, while its membership problem is solvable in linear time. For the problem whether a given Church-Rosser or context-free language belongs to the intersection we show completeness for the second level of the arithmetic hierarchy. The equivalence of Church-Rosser and context-free languages is Π1-complete. It is proved that all considered intersections are pairwise incomparable. Finally, closure properties under several operations are investigated.
A PUMPING CONDITION FOR ULTRALINEAR LANGUAGES
Authors: MAGALINI ENZO , PIGHIZZINI GIOVANNI
Published: October 2007

A pumping condition for ultralinear languages is proved. Some examples are given using that condition to state lower bounds on the rank of some ultralinear languages and to prove that a certain language is not ultralinear. The restriction to the metalinear case is also investigated.
ON METALINEAR PARALLEL COMMUNICATING GRAMMAR SYSTEMS
Authors: MALCHER ANDREAS , SUNCKEL BETTINA
Published: October 2007

A generalization of centralized and returning parallel communicating grammar systems with linear components (linear CPC grammar systems) is studied. It is known that linear CPC grammar systems are more powerful than regular CPC grammar systems and that CPC grammar systems with context-free components are more powerful than linear CPC grammar systems. Here, the intermediate model of metalinear CPC grammar systems is studied. This is a CPC grammar system where the master is allowed to use metalinear rules whereas the remaining components are restricted to use linear rules only. It turns out that metalinear CPC grammar systems are more powerful than linear CPC grammar systems and less powerful than CPC grammar systems with context-free components. Furthermore, it is shown that all languages generated by metalinear CPC grammar systems are semilinear.