bluuebunny/crossref_metadata_2025 huggingface dataset:
The volatile exudates from germinating pea seeds of different viability and vigor
Authors: Gorecki R. J. , Harman G. E. , Mattick L. R.
Published: May 2008

Pea seeds var. Kriter were stored aseptically at 92% relative humidity and 30 °C. After 0, 4, 6, 8, or 10 weeks of storage, viability, vigor, and volatile exudates were determined on sublots of seeds. As storage time increased, vigor, as measured by dehydrogenase activity, growth of embryonic axes, and conductivity decreased. Later, viability also decreased. Imbibing and germinating pea seeds produced ethanol, acetaldehyde, and lesser amounts of methanol. No qualitative differences in volatile exudates were observed from germinating seeds regardless of age or storage condition. Nonaged seeds with highest vigor produced the smallest amounts of volatiles, but with increased aging the quantities of ethanol and acetaldehyde gradually increased. Dry seed produced small quantities of both volatiles. The amount of these compounds produced reached a maximum between 12 and 48 h of germination. Infestation of seed samples with Enterobacter cloacae or Trichoderma harzianum reduced the quantities of these compounds measured. These results indicate that determinations of acetaldehyde and ethanol in the space over germinating seeds by means of gas chromatography may be a useful seed vigor test.
Responses of soil microorganisms to volatile exudates from germinating pea seeds
Authors: Norton J. M. , Harman G. E.
Published: May 2008

Responses of soil microorganisms to volatile exudates from germinating pea seeds of differing quality were determined. Germination of sclerotia of Rhizoctonia solani and Sclerotium rolfsii and subsequent hyphal growth were stimulated by exposure to volatiles from aged but not nonaged pea seeds. Hyphae grew preferentially toward aged seeds. In natural soil, bacterial and fungal populations showed significant increases after exposure to volatiles from aged seed. For example, Fusarium spp. and Pseudomonas spp. showed increases of 79 and 2200%, respectively, over their original population levels after a 48-h exposure to volatiles. Conversely, Pythium populations and associated seed-rotting potential of soil decreased in natural soils exposed to volatiles. In autoclaved soils infested with P. ultimum (PHP4), Pythium populations increased dramatically after exposure to volatiles from aged pea seeds. In soils infested with either soil fungi or bacteria in addition to P. ultimum, Pythium levels remained constant or decreased, respectively, with time of exposure. Exposure to the volatiles from aged pea seeds stimulated soil microbial activity. These results suggest that Pythium germlings, when unable to reach a host, are subjected to microbial antagonism in the presence of the native soil microflora. A decrease in cucumber seed rot coincided with decreases in Pythium numbers.
Avena atlantica, a new diploid species of the oat genus from Morocco
Authors: Baum Bernard R. , Fedak George
Published: May 2008

A newly discovered diploid oat species from Morocco is described morphologically and karyotypically. Some important morphological and karyotypical features are stressed and documented. Its habitat and distribution are also described.
Growth of submersed macrophyte communities in the St. Clair – Detroit river system between Lake Huron and Lake Erie
Authors: Schloesser Donald W. , Edsall Thomas A. , Manny Bruce A.
Published: May 2008

Growth of submersed aquatic macrophytes was determined from observation and on the basis of biomass of samples collected from April to November 1978 at seven study sites in a major river system of the Great Lakes, the St. Clair – Detroit river system between Lake Huron and Lake Erie. Growth usually began between April and June, peaked between July and October, and decreased by late November. Maximum biomass at six of the seven sites (118–427 g dry weight m−2) was similar or greater than that reported in other rivers at similar latitudes. Seasonal growth of the abundant taxa followed one of three seasonal patterns at each study site: one dominant taxon grew alone; codominant taxa grew sympatrically without species succession; and codominant taxa grew sympatrically with species succession. Differences in growth and seasonal succession of some taxa were apparently caused by the presence or absence of overwintering plant material, competition, and life-cycle differences.
Experimental evidence of heterothallism in Cronartium ribicola
Authors: Hunt R. S.
Published: May 2008

By isolating cankers and by bagging them during the appropriate seasons Cronartium ribicola Fisch. was found to be heterothallic. The flies Paracacoxenus guttatus Hardy & Wheeler and Megaselia (Aphiochaeta) spp. were particularly attracted to pycnia and were readily caught in sticky traps. It is postulated that these are the main insects responsible for cross-fertilization of Cronartium ribicola.
Évolution holocène d'une tourbière à pergélisol (Québec nordique)
Authors: Couillard Line , Payette Serge
Published: May 2008

The Holocene development of a peat plateau peatland in northern Québec has been reconstructed from present vegetation and buried macrofossil analogues found in peat. This peatland is presently formed by nine morphological units characterized by homogenous site conditions (drainage, topography, and vegetation cover). Seven ombrotrophic and eight minerotrophic vegetation types are found in the peatland, but the ombrotrophic types cover 66% of the peatland surface. Reconstitution of the Holocene peatland development from 3700 BP to present was based on the succession of bryophytes within the morphological units. Between 3200 and 2700 BP, minerotrophic vegetation such as sedge fens, pools, and tamarack woodlands (now locally extinct) dominated the peatland. Peat plateaus and palsas were progressively formed after 2700 BP. The expansion of these units is closely related to several cooling periods that occurred after 2700, 1400, 1100, 700, and 150 BP. Thermokarst pools were created within the peat plateaus around 1100 BP after a burn, and other similar depressions formed around 340 BP and Present because of the recent climatic warming. Plant successions show that long-term vegetation development in the peatland is rather complex and diversified. These successions indicate that peat plateaus gradually developed during the last thousand years in relation with topographical conditions, drainage, vegetation cover, fire, and climate. Palsas were formed more recently than peat plateaus, between 700 and 500 years BP, and around 150 years BP.
Penicillin action stimulating growth and metabolism in seedlings of rice (Oryza sativa)
Authors: Mukherji S. , Biswas A. K.
Published: May 2008

Penicillin promoted elongation of rice (Oryza sativa L.) seedlings; the relative promotion of shoot elongation was stronger than that of root elongation. Nucleic acids and protein were maintained at much higher levels in seedlings treated with penicillin, the increment of these metabolites being more pronounced in the embryo than in the endosperm. α-Amylase, RNase, and ATPase of endosperm and indoleacetic acid (IAA) oxidase activities of the entire seedlings were enhanced in penicillin treatments. Penicillin caused small increments in respiration rates of seedlings. IAA-induced growth inhibition of intact seedlings could be reversed completely to a growth promotion by joint application of penicillin with IAA. The length of the second leaf sheath of a dwarf rice cultivar was increased by penicillin which further enhanced the gibberellin-induced response. The levels of gibberellinlike substances were increased by penicillin treatments, whereas the IAA level remained unchanged. In penicillin-treated seedlings, more IAA was transported from endosperm to embryo. The stimulating effect of penicillin on rice seedling elongation was partially reversed by abscisic acid and the interaction appeared to be of a noncompetitive nature.
Leptomelanconium pinicola comb. no v. and associated needle blight of pines
Authors: Hunt R. S.
Published: May 2008

Examination of herbarium records indicates that needle fungi identified as Stilbospora pinicola, Gloeocoryneum cinereum, and Leptomelanconium cinereum are the same and their characteristics fit the genus Leptomelanconium. For this group I propose the name Leptomelanconium pinicola (Berk. & Curtis) R. S. Hunt comb. nov. This fungus is associated with a severe needle blight of ponderosa and lodgepole pines in western Canada and western United States.
The influence of temperature on tumorigenesis induced by various strains of Agrobacterium tumefaciens
Authors: Charest P. J. , Dion P.
Published: May 2008

Adventitious root formation, tumor surface morphology, and secondary shoot formation were three morphological markers associated with tumorigenesis induced by Agrobacterium tumefaciens (Smith and Townsend) Conn on Kalanchoe tubiflorae Hamet. These markers were used to characterize tumorigenesis induced at an incubation temperature of 20 or 27 °C, by A. tumefaciens strains assigned to biotype 1, 2, or 3. Adventitious roots were observed with all but one of the strains tested. Tumor surface morphology and formation of secondary shoots depended upon particular strain–temperature combinations. For biotype 1 and 2 strains, an incubation temperature of 27 °C modified tumor surface morphology with nopaline-utilizing strains and decreased the rate of formation of secondary shoots with octopine-utilizing strains. For biotype 3 strains, tumorigenesis itself was inhibited at 27 °C. A similar thermosensitivity of tumor induction by biotype 3 strains was also observed on tomato, whereas several of the strains were not thermosensitive on sunflower.
Mapping of a major locus controlling seed dormancy using backcrossed progenies in wheat (Triticum aestivumL.)
Authors: Torada Atsushi , Koike Michiya , Ikeguchi Shojiro , Tsutsui Ichiro
Published: May 2008

Seed dormancy is an important factor regulating preharvest sprouting (PHS) but is a complex trait for genetic analysis. We previously identified a major quantitative trait locus (QTL) controlling seed dormancy on the long arm of chromosome 4A (4AL) in common wheat. To transfer the QTL from the dormant lines ‘OS21-5’ and ‘Leader’ into the Japanese elite variety ‘Haruyokoi’, which has an insufficient level of seed dormancy, backcrossing was carried out through marker-assisted selection (MAS) using PCR-based codominant markers. Nineteen BC5F2plants with homozygous alleles of ‘OS21-5’ or ‘Haruyokoi’ were developed and evaluated for seed dormancy under greenhouse conditions. The seeds harvested from plants with ‘OS21-5’ alleles showed a clearly high level of dormancy compared with seeds from plants with ‘Haruyokoi’ alleles. Additionally, the dormancy phenotype of BC3F3seeds harvested from 128 BC3F2plants with homozygous alleles of ‘Leader’ or ‘Haruyokoi’ showed a clear difference between these alleles. The QTL on 4AL confers a major gene, Phs1, which was mapped within a 2.6 cM region. The backcrossed lines developed in this study can be important sources for improving PHS resistance in Japanese wheat and for analyzing the mechanism of seed dormancy. MAS was useful for the development of near-isogenic lines in this complex trait, to facilitate the molecular dissection of genetic factors.
Mutations of thewithered(whd) gene inDrosophila melanogasterconfer hypersensitivity to oxidative stress and are lesions of the carnitine palmitoyltransferase I (CPT I) gene
Authors: Strub Benjamin R. , Parkes Tony L. , Mukai Spencer T. , Bahadorani Sepehr , Coulthard Alistair B. , Hall Nichole , Phillips John P. , Hilliker Arthur J.
Published: May 2008

Since some oxygen defense mutants of Drosophila melanogaster exhibit a crinkled wing phenotype, a screen was performed on strains bearing mutant alleles conferring a visible wing phenotype to determine whether any were hypersensitive to oxidative stress. One mutant, withered (whd), was found to be sensitive to both dietary paraquat and hyperoxia. New alleles of whd were induced on a defined genetic background and strains carrying these alleles were also found to be sensitive to oxidative stress. To identify the product of the whd gene we used a sequence-based positional candidate approach and by this method we determined that whd encodes carnitine palmitoyltransferase I (CPT I), an enzyme of the outer mitochondrial membrane that is required for the import of long-chain fatty acids into the mitochondria for β-oxidation. Although this function is not vital under laboratory conditions, whd adults were found to be highly sensitive to starvation and to heavy metal toxicity relative to controls. This work uncovers a novel relationship between fatty acid metabolism and reactive oxygen metabolism. Further, these results in conjunction with past research on whd and on mammalian CPT I support the hypothesis that CPT I serves a vital function in the response to thymine supplementation.
Development of PCR-based SCAR and CAPS markers linked to β-glucan and protein content QTL regions in oat
Authors: Orr Winson , Molnar Stephen J.
Published: May 2008

A key breeding objective in oat ( Avena sativa L.) is cultivars with high and low β-glucan content. In a targeted strategy to develop PCR-based markers linked to published β-glucan content quantitative trait loci (QTLs) regions, 15 random amplified polymorphic DNA (RAPD) fragments were cloned and their sequences used to design sequence-characterized amplified region (SCAR) and cleaved amplified polymorphic sequence (CAPS) primers. The 13 derived SCAR markers and 2 derived CAPS markers were mapped on either the ‘Kanota’ × ‘Ogle’ (KO) or the ‘Terra’ × ‘Marion’ (TM) oat reference map. In addition, 3 previously reported SCAR markers were characterized further. Ten SCAR markers and one CAPS marker were associated with β-glucan QTL regions and many of these are also associated with QTLs for protein content or other traits. These markers have the potential to help define homologous and homoeologous relationships in oat and investigate the complex genetics of β-glucan and protein content.
Variations of tandem repeat, regulatory element, and promoter regions revealed by wheat–rye amphiploids
Authors: Tang Zong-Xiang , Fu Shu-Lan , Ren Zheng-Long , Zhou Jian-Ping , Yan Ben-Ju , Zhang Huai-Qiong
Published: May 2008

To better understand the evolution of allopolyploids, 4 different combinations between wheat ( Triticum aestivum L.) and rye ( Secale cereale L.) including 12 F1hybrids and 12 derived amphiploids were analyzed and compared with their direct parental plants by PCR analysis using 150 wheat SSR (single sequence repeat) markers and by FISH analysis using a rye-specific repetitive sequence (pSc200) as a probe. Nine SSR markers amplified rye-specific fragments whose sizes ranged from 471 bp to 1089 bp. These fragments contain regulatory elements and (or) promoters. Some of these fragments were amplified from all 24 progenies, while others were amplified from a subset of the progenies. The disappearance of rye-specific fragments from some progenies was caused by sequence elimination or DNA modification. Marker Xgwm320 amplified a new fragment (403 bp), a rye-specific tandem repeat, from some of the progenies. Twenty-eight SSR markers displayed microsatellite variation in progenies derived from ‘Chinese Spring’ × ‘Jinzhou-heimai’, but none of the 150 SSR markers displayed microsatellite variation in the progenies derived from the other three combinations. FISH signals of pSc200 were eliminated from one telomere/subtelomere of 4 chromosomes of ‘Kustro’ during allopolyploidization and expanded in amphiploids derived from ‘Chinese Spring’ × ‘AR106BONE’. Thus, allopolyploidization in wheat–rye can be accompanied by rapid variation of tandem repeats, regulatory elements, and promoter regions. The alterations of repetitive sequence pSc200 indicate coordination between the constituent genomes of the newly formed amphiploids. Different genetic backgrounds of parents appear to affect genome changes during allopolyploidization.
Comparative genomic analysis of the whale (Pseudorca crassidens) PRNP locus
Authors: Kim Dae-Won , Chae Sung-Hwa , Kang Bo-Ra , Choi Sang-Haeng , Kim Aeri , Woo Seonock , Park Hong-Seog
Published: May 2008

There have been many studies of the morphology, behavioral audiograms, and population structure of the false killer whale ( Pseudorca crassidens ), but sequencing, mapping, and functional and comparative genomics studies are still largely unknown. In this paper, we sequenced three novel BAC clones corresponding to a total length of 308 kb and spanning the PRNP, PRND, and RASSF2 loci, and conducted comparative genomic analysis to examine the genomic structure of the false killer whale PRNP locus. We determined that the three genes show a high degree of conservation in their syntenic regions with respect to gene order, gene orientation, and the predicted coding sequence (CDS) between human and whale, whereas PRNT was not detected in whale. Interestingly, the predicted CDS in whale PRNP contained a novel type of 4-copy octarepeat resulting from a 24 bp deletion when compared with the human sequence. In addition, we identified a novel 1869 bp repeat unit in a region that is non-syntenic to human and cow sequences and is therefore considered to be whale-specific sequence. Our results will provide novel insights into the genomic changes that have occurred during evolution of mammalian PRNP loci, and may also have implications for research into prion disease.
Reassessing domestication events in the Near East: Einkorn and Triticum urartu
Authors: Heun Manfred , Haldorsen Sylvi , Vollan Kari
Published: May 2008

To reassess domestication events in the Near East, accessions of Triticum urartu from a well-described sampling were combined with a representative sample covering the Karacadağ Einkorn wheat domestication. The observed DNA separation between the two wheat species accounts for the main differentiation, but geographic variation within T. urartu is evident and so is the domestication scenario among wild, feral, and domesticated Einkorn. In contrast to the clear DNA differences, it is difficult to separate living T. urartu from wild Einkorn based on morphology. With archaeobotanical material a distinction of carbonized remains of these two wheats is considered to be impossible. We reviewed the differences concerning morphology and maturity and combined these observations with information about archaeological sites in the Near East. In conclusion, the excavation sites in the middle Euphrates may contain T. urartu rather than Einkorn wheat and T. urartu may underlie the reported occurrence of the extinct 2-grained domesticated “Einkorn” wheat. The first Einkorn wheat domestication sensu stricto seems to have happened around the Karacadağ, as reported earlier. The human dimension shown by the excavation of Göbekli Tepe can explain why domesticated phenotypes might have spread quickly.
Dernières avancées sur les carrefours giratoires
Authors: Pellecuer Luc , St-Jacques Michèle
Published: May 2008

Le carrefour giratoire est un aménagement routier qui a connu un fort succès au cours des années 1970 et est désormais pratique courante en Europe grâce à ses performances en termes de capacité et de sécurité. Néanmoins, ce concept d’ingénierie est d’usage beaucoup moins répandu dans le reste du monde et, notamment, en Amérique du Nord où la population reste circonspecte à son propos. Pourtant, lors de mises en application, les préjugés négatifs se transforment rapidement en opinion favorable. De plus, lorsque l’implantation est précédée d’une planification et d’une conception minutieuses, accompagnée d’une campagne de communication efficace, le carrefour giratoire peut être adapté à l’environnement et aux conducteurs nord-américains. De nombreux guides proposent un cadre pour la conception des carrefours giratoires, mais il n’existe pas encore de normes établies. Les efforts de recherche actuels visent à mieux comprendre le fonctionnement de ces aménagements routiers afin de pouvoir tirer des règles de conception plus efficaces et pertinentes.
Simulating the effects of climate change on the ice regime of the Peace River
Authors: Andrishak R. , Hicks F.
Published: May 2008

Winter can be a critical time on many rivers, during which ice conditions and a number of environmental factors can lead to rapidly developing and damaging flood events. Also, in northern Canada, rivers are important for both summer (ferry) and winter (ice bridge) transportation; however, during periods of variable ice conditions these transportation links are temporarily interrupted. As a result, northern communities can become isolated for periods of time. With climate warming becoming an increasing concern, it is important to know how elevated temperatures might affect river ice covers so that we can assess the implications for ice jam events, hydropower dam operation, and winter transportation. The Peace River in northern British Columbia and Alberta was used as a case study in this paper to assess the validity of a newly developed, public domain, thermo-hydraulic river ice model, River1D. The Canadian second-generation coupled global climate model (CGCM2) provided an offset for the historical air temperature input, and a future climate analogue for the mid-21st century ice regime was generated. The historical and future climate simulation results indicated significant potential reductions in the duration and extent of ice cover on the Peace River and a longer period over which the river will be impassible by ferry or ice bridge. Specifically, the number of days an ice bridge could be sustained at the Shaftesbury Ferry site was shown to decrease by 60% to 78%.
Safety performance of freeway sections and relation to length of speed-change lanes
Authors: Sarhan M. , Hassan Y. , Abd El Halim A. O.
Published: May 2008

The design of freeway entrances and exits requires managing the high operating speeds on the through lanes and the intense lane-change manoeuvres due to merging and diverging. Therefore, adequate lengths between these entrances and exits and provision of adequate speed-change lanes would help drivers execute such tasks safely. Most of the previous research has focused on analyzing operational conditions of the merge and diverge areas based on kinematic analysis of speeds and distances. However, little research has addressed the safety effects of merging and diverging and the interrelationship with geometric features. In this study, 26 interchanges were selected to quantify the effects of ramp terminal spacing and traffic volumes on safety performance through regression analysis. Negative binomial models were developed using 5 year collision data. Modelling attempts resulted in several statistically significant models relating traffic volumes and geometric features to collision frequency.
Effect of jet aeration on hydrodynamic forces on plunge pool floors
Authors: Pinheiro A. N. , Melo J. F.
Published: May 2008

The effect of jet aeration on the mean hydrodynamic forces applied on plunge pool floors was investigated. A mathematical expression is proposed to estimate the buoyancy coefficient reflecting the aeration effect, including contributions from previous authors. A correction of the theoretical values resulting from this expression based on data obtained in an experimental setup with vertical submerged rectangular (two-dimensional) aerated jets is proposed. The effect of the buoyancy coefficient is introduced in the integration of the hydrodynamic pressures over slabs of the plunge pool floor. Dimensionless forces on the upper faces of the slabs are determined for different air concentrations of the impinging jet. The effect of jet aeration entering the plunge pool on the uplift force applied in the lower faces of the slabs in the case where a waterstop failure occurs is also analysed.
Flow over a fixed rough dune
Authors: Balachandar Ram , Patel V. C.
Published: May 2008

Using a laser Doppler velocimeter (LDV) system, experiments were carried out to obtain detailed information on the flow over a long train of fixed two-dimensional rough-wall dunes. The experiments provide quantitative data on conventionally averaged velocity and turbulence parameters, as well as insights on the flow structures that play a crucial role in sediment transport. The results indicate that the shape of the dunes has a major influence on the flow features, whereas the effect of near-bed roughness is limited to the wall region extending to a distance of about 80% of the dune height about the crest. However, the length of the separation eddy seems to be influenced by the near-bed roughness. As in flow over a smooth dune, the turbulence data reveal large peaks along a line roughly coinciding with the shear layer emanating from the separation at the crest. However, the location of the peak turbulence is farther extended into the flow away from the bed with increasing bed roughness. Moreover, with increasing roughness the magnitude of the peak is also reduced. A secondary peak in the streamwise turbulence profiles is noticed at some distance from the bed. This feature is not influenced by the near-bed roughness and indicates sustenance of turbulence generated by the previous dune and relates to the convection of the upstream flow history. Based on the results obtained at several stations between two successive dune crests, one can conclude that the quantitative effect of roughness itself is limited to the near-bed region in the measurements at all levels.
Effect of geographic variation and jack pine introgression on disease and insect resistance in lodgepole pine
Authors: Wu Harry X. , Ying Cheng C. , Muir John A.
Published: May 2008

Incidence of western gall rust (Endocronartiumharknessii (J.P. Moore) Y. Hiratsuka), stalactiform blister rust (Cronartiumcoleosporioides Arth.), needle cast (Lophodermellaconcolor (Dearn.) Darker), and sequoia pitch moth (Synanthedonsequoiae (Hy. Edwards) (Lepidoptera: Sesiidae)) attacks were investigated in a lodgepole pine (Pinuscontorta Dougl. ex Loud, van latifolia Engelm.) provenance–family test plantation located at Red Rock Tree Improvement Station, Prince George, British Columbia. This plantation contains 778 wind-pollinated families from 53 provenances in British Columbia, Alberta, and the Yukon Territory. Pest incidence was assessed in 1993 when the plantation was 21 years old. Provenance had a significant effect on resistance to the four disease and insect attacks. Regression models using latitude, longitude, and elevation as predictors accounted for 38% to 80% of the provenance variation in pest incidence. Geographic patterns of genetic variation in pest resistance essentially followed longitudinal and elevational clines. The most interesting finding is the strong relationship between pest incidence and provenance distance to the western limit of the natural range of jack pine (Pinusbanksiana Lamb,): the closer a lodgepole pine provenance is to the edge of jack pine distribution, the higher is its resistance to the pests. We hypothesize that jack pine introgression may have played a significant role in the evolution of pest defense in lodgepole pine. Effective selection and breeding for pest resistance in lodgepole pine may have to look beyond the intraspecific gene pool.
A hedonic price function for forest land in Sweden
Authors: Roos Anders
Published: May 2008

A hedonic price model was employed to analyze prices for forest land in Sweden, which is primarily used for timber production. The investigation was based on 143 sales in 1992, and the independent variables describe the conditions for profitable forest management. Estimates were performed using the Box–Cox transformed specification and likelihood ratio tests. The results indicate a positive relationship between the per-hectare price of forest land and (1) the proportion of productive forest land in relation to the total forest area on the estate, (2) the mean standing volume, and (3) the mean site productivity on productive forest land. The parcel area has a negative effect on per-hectare prices. Population density in relation to the area of forest land in the county displays a positive relationship with price. The price of forest land was not significantly lower in regions with buyer restrictions than in other parts of Sweden.
Landscape-scale evaluation of understory light and canopy structures: methods and application in a neotropical lowland rain forest
Authors: Clark David B. , Clark Deborah A. , Rich Paul M. , Weiss Stuart , Oberbauer Steven F.
Published: May 2008

Light is a key resource controlling tree regeneration in the understory of closed-canopy old-growth forests. To evaluate the distribution of understory light environments at a landscape scale, we used stratified random sampling in a 500-ha stand of Costa Rican tropical rain forest. Fifteen 100 m long transects were placed using random coordinates within two soil–geomorphology units (flat alluvial terraces and dissected ridge-slope-swale terrain). At 2.5-m intervals we measured canopy height and slope angle, classified topographic position, and took canopy photographs with a fish-eye lens at 1 and 3 m above the ground (and at 0.6 and 5 m height at five stations per transect). Photographs were analyzed for global site factor (GSF), which is analogous to the percentage of full sun radiation reaching a point. Canopy height and GSF at 1 and 3 m above the ground were significantly autocorrelated (Moran's I) at 2.5-m intervals. The autocorrelation rapidly declined at greater intervals, reaching nonsignificance at ca. 20 m. Both canopy height and GSF at 3 m height had a weak tendency for negative autocorrelations at intervals of 25–50 m. Median canopy height (615 stations) was 23 m (range 0–37). Gaps (canopy height ≤2 m, Brokaw 1982) were only 1.5% of sample points. Gaps were more frequent on steep slopes than on terraces, ridgetops, swales, and gentle slopes. Canopy height varied significantly across this topographic gradient. At all four heights (0.6, 1, 3, and 5 m) median GSF was ≤2.4%. GSF values >8% accounted for only 3% of the total sample (N = 1380). GSF was only weakly negatively correlated with canopy height and the relation was not monotonie. Under canopies 13-19 m tall, nearly all GSF values were ≤5%. Higher GSFs were more frequent under both shorter and taller canopies. Given the observed variance in GSF and canopy height, 100–200 points separated by intervals of ≥20 m are necessary to measure the forest-wide means of these variables to ±10%. We discuss implications of these results for current approaches to modeling understory light based on canopy characteristics. We compared the random background of light environments from 1–3 m above the ground at La Selva with those occupied by saplings of pioneer and nonpioneer tree species. The two pioneers (Cecropia spp.) occurred in microsites significantly brighter than random sites, while sapling microsites of all five nonpioneer species were significantly darker than random. Comparing the landscape-scale distribution of key resources with species' actual distributions at similar scales offers a quantitative method for assessing plant life histories within and among forests.
Small-area estimates using model-based methods
Authors: Kangas Annika
Published: May 2008

In small areas, the number of sample plots is usually small, and the classical estimators have a large variance. Information from nearby areas can be utilized to improve the subarea estimates using either nonparametric or parametric models. In this study, a number of model-based estimators for small-area estimation are presented. To illustrate the presented methods a numerical example in a real inventory situation is given. The auxiliary information used in this study is pure coordinate information, but the methods are applicable also for other kinds of auxiliary information. The object of this study is to compare the features of the presented small-area estimation methods and to discuss the applicability of these methods in different situations.
Hydrogeology of brook trout (Salvelinusfontinalis) spawning and incubation habitats: implications for forestry and land use development
Authors: Curry R. Allen , Devito Kevin J.
Published: May 2008

We demonstrated that nearshore spawning and incubation habitats of brook trout (Salvelinusfontinalis) are manifestations of lenses of coarse overburden materials underlying the nearshore zone. Lenses directed and accelerated groundwater flow into the habitats. They were <17 m wide, >1 m thick, and could be restricted to the nearshore zone or extend at least 20 m into the terrestrial catchment. Recharge areas necessary to sustain discharge in the habitats were estimated to encompass 3–10 ha, or 1–97%, of the associated terrestrial catchment. A 90-m buffer zone adjacent to the shoreline protected only 9–55% of the required recharge area. A hydrological approach to defining habitat protection measures is suggested.
Nitrate in soil water in three Norway spruce stands in southwest Sweden as related to N-deposition and soil, stand, and foliage properties
Authors: Nohrstedt Hans-Örjan , Sikström Ulf , Ring Eva , Näsholm Torgny , Högberg Peter , Persson Tryggve
Published: May 2008

N-cycling was studied at three Norway spruce (Piceaabies (L.) Karst.) sites located within a distance of 30 km in southwest Sweden. Nitrate concentrations in soil water at 50-cm depth differed substantially between the three sites, annual site means being 0, 1, and 9 mg N•L−1. Using simulated runoff, the leaching of inorganic N from the two sites with the highest concentrations was estimated at, respectively, 7–8 and 19–30 kg•ha−1 during the hydrological year 1991–1992. The N-deposition measured as throughfall was 31 kg•ha−1 on the second site, suggesting that it was close to being N-saturated. The differences in nitrate concentration and estimated leaching across sites were not related to differences in forest growth or suggested symptoms of forest decline, such as canopy defoliation and nutrient deficiency. Nitrate concentrations were unrelated to N-deposition in an open field, but positively related to N-deposition in throughfall. However, the difference in N-leaching between the two main sites was much larger than the difference in N-deposition in throughfall. The difference in leaching seemed related to soil conditions. The soil with the highest leaching had the largest potential nitrification and a low C/N ratio (17–20) in the upper part of the profile. Nitrate concentrations in the soil water were positively related to the concentrations of arginine and 15N in foliage, which supports the use of these two variables as indicators of forests approaching N-saturation.
Quantifying the effects of temporal autocorrelation on climatological regression models using geostatistical techniques
Authors: Strachan Ian B. , Harvey L. Edward
Published: May 2008

When time-dependent data are used in regression models, temporal autocorrelation violates ordinary least squares assumptions and impedes their proper testing and interpretation. The problem of temporal autocorrelation is exacerbated by the uneven temporal spacing inherent in many data sets. Using simple linear regression models of stomatal conductance as examples, we compare the effectiveness of two methods for removing temporal autocorrelation from regression models (first-differencing and Cochrane–Orcutt) and we introduce the geostatistical technique of semivariograms as a method for quantifying temporal autocorrelation in uneven time series. The Cochrane–Orcutt method proved more effective than first-differencing at removing autocorrelation and produced regression models without changing the significance of the independent variables. Semivariograms were used to quantify the time dependence of the unevenly spaced stomatal conductance time series. This technique revealed the dominant autocorrelation at the minimum time lag (0.5 h) and the 24-h periodicity caused by the climatological variables used in the model. We conclude that geostatistical techniques provide a robust method for quantifying temporal structure and periodicity in unevenly spaced time series.
Allelopathic inhibition of black cherry by fern, grass, goldenrod, and aster
Authors: Horsley Stephen B.
Published: May 2008

Small black cherry (Prunusserotina Ehrh.) seedlings grow slowly and soon die in low-density cherry–maple (Acerrubrum L.) orchard stands colonized by a dense ground cover of bracken fern (Pteridiumaquilinum L.), wild oat grass (Danthoniacompressa Aust.), goldenrod (Solidagorugosa Ait.), and flat-topped aster (Asterumbellatus Mill.). Studies of orchard stand persistence indicated that allelopathic interference occurred between black cherry seedlings and the herbaceous ground-cover plants. Foliage extracts of fern, goldenrod, and aster inhibited seed germination; aster foliage extract inhibited both shoot and root growth of seedlings growing on cotyledonary reserves; foliage extracts of fern, grass, goldenrod, and aster and root washings of goldenrod and aster inhibited shoot growth and dry weight accumulation of seedlings that had exhausted cotyledonary reserves. Soil from the upper horizons of an orchard stand did not moderate the toxicity of the herbaceous foliage extracts or root washings.
Characteristics of damage in tree-length white spruce logs caused by the white-spotted sawyer, Monochamusscutellatus
Authors: Cerezke Herbert F.
Published: May 2008

Damage caused by the white-spotted sawyer, Monochamusscutellatus (Say), to felled white spruce, Piceaglauca (Moench) Voss, in northern Alberta was studied to provide data for improving a damage assessment technique. Numbers, density, and size of larval entrance holes, length of larval galleries, and diameter of adult exit holes were examined on three 122-cm-long log sections cut near the butt, middle, and top of each of 30 trees. Information on larval development and survival and adult emergence was also obtained.Size of larval entrance and adult exit holes and gallery length decreased from the butt to top of the tree, numbers of entrance holes were similar at the three stem positions, and density of entrance holes increased from butt to top on both south and north aspects. The density of entrance holes around the logs showed two maxima, while the mean density was approximated slightly above midlevel on south and north aspects. Larval galleries extended to an average maximum depth of 7.5 cm into the wood. About 25% of adults emerged 1 year after oviposition, the rest emerged after 2 years. Mortality of M. scutellatus within the logs averaged 71%. The results are discussed in relation to sampling problems for damage assessment in felled and standing fire-killed trees.
Cytochemical and subcellular organization of root apical meristems of dry and germinating jack pine embryos
Authors: Mia A. J. , Durzan D. J.
Published: May 2008

By cytochemical and electron microscopic methods, the emerging radicle of Pinusbanksiana Lamb. was shown to contain an abundance of food reserves largely proteins, lipids, and starch grains. After 4 days of imbibition, the food reserves were dispersed to the daughter cells that tended to form through a sequence of divisions, linear arrays of adhering cells. The main cytochemical changes were associated with the later stages of imbibition and the consumption of carbohydrates and nitrogenous compounds for the synthesis of newly dispersed macromolecules. Peroxidase (EC 1.11.1.7) not found to any significant extent in the dry embryo, appeared by day 4 in the root cap and epidermal cells. As for DNA synthesis, cells of the quiescent zone were shown by autoradiography to incorporate very little [methyl-3H]thymidine. By contrast, most cells in the radicle incorporated thymidine in advance of the first wave of cell division between 3 to 4 days.The initial tight packing of subcellular organelles and the high lipid content of dry cells made the evaluation of subcellular changes difficult. In the nucleus and cytoplasm, the increase of ribosomes and polysomes was supported by the increased cytoplasmic staining for total RNA and acidic proteins. In emerging radicles, the overall redistribution of organic reserves and the associated subcellular reorganization related to the tactical displacement of cells and to new channels for the initial uptake of water and nutrients from the soil.
Fire history and rotations in the New Brunswick Acadian Forest
Authors: Wein Ross W , Moore Janice M.
Published: May 2008

From an analysis of fire records in New Brunswick for the period of 1920–1975, the fire history and rotation patterns are presented. Mean and median annual burns have been 12 000 ha (0.15% of the province) and 2500 ha (0.03% of the province), respectively, but the fire rotations have been widely different for different vegetation types. The most extensively burned vegetation type of red spruce – hemlock – pine has had a fire rotation period of 230 years. Hardwood and high-elevation conifer vegetation types have had fire rotation periods of over 1000 years.
Growth of the particle hoard share of production of wood-based panels in industrialized countries
Authors: Buongiorno Joseph , Oliveira Ronald A.
Published: May 2008

The growth of the share of particle board production (measured as a fraction of total wood-based panels) has been analyzed using data from 25 industrialized countries. The trends in each country during the period 1955–1973 were represented by logistic models, analysis of which suggested the following conclusions. The particle board share of panel production was expected to reach a long-term maximum which could be estimated for most industrialized countries; this maximum varied widely from country to country. In most countries, except for Canada, Finland, Sweden, and the United States, the particle board share seemed close to having reached its long-term maximum in 1973. Countries in which the particle board share grew more initially slowly tended to be those in which the long-term maximum share was higher. The long-term maximum share of particle board was significantly lower in eastern European countries than in market economies. Using information from the other 21 countries allowed inferences regarding the long-term growth of particle board in Canada, Finland, Sweden, and the United States where particle board is still a small part of total panel production. Increasing distance from the Democratic Republic of Germany, which initiated particle board production, and the availability of a large supply of roundwood have generally delayed the time of adoption of particle board. Other things being equal, the growth rates of the particle board share of total panel production appeared to be higher in countries with high economic growth and lower in countries with high wood availability.
Impact of world economic and demographic growth on forest-products consumption and wood requirements
Authors: Buongiorno Joseph , Grosenick Gerold L.
Published: May 2008

A model fitted to cross-sectional observations is proposed which links the growth of consumption of structural wood materials and paper and paperboard to the economic and demographic growth of developed and developing economies. It was found that the response of consumption per capita to a specific growth of income per capita decreases systematically as the level of consumption attained increases. The consumption functions, for both groups of products, differed significantly for high-income and low-income countries. A set of input-output relationships was also established to estimate the amounts of wood pulp and industrial roundwood required to produce specific amounts of structural and paper materials. Those relationships have significantly shifted during the period 1961–1971, indicating an improvement in the efficiency of raw-material usage by the wood-products industries. The full model was applied to calculate the levels of consumption and of raw-material requirements consistent with Timbergen's indicative world plan (Timbergen, J. 1976. Development and environment aims: an intuitive view. In World modeling: a dialogue. Editedby C. W. Churchman and R. O. Mason. North Holland, Amsterdam, pp. 55–61). Given Timbergen's targets for world economic and demographic growth, a considerable improvement would occur in the balance of consumption between developed and developing countries but consumption per capita of industrial roundwood equivalent would still be three times higher in developed countries by the year 2010. The main growth of industrial roundwood consumption would occur in the paper and paperboard industry which would consume 65% of the world output by the end of the period. Developing countries would by that time become the main market for paper and paperboard products.
Wound closure in sugar maple: adverse effects of defoliation
Authors: Wargo Philip M.
Published: May 2008

Twenty-three sugar maple trees, Acersaccharum Marsh., that had been defoliated by hand for 3 consecutive years (1971, 1972, and 1973) and nine undefoliated trees were wounded with a drill bit in March 1974. After two full growing seasons, wound areas on defoliated trees were larger than those on undefoliated trees because more bark tissue died originally around the wounds on defoliated trees, and because there was less wound closure resulting from poorer radial growth. There was no significant increase in internal discoloration, but decay was found in two defoliated trees. In undefoliated trees, wound area was highly correlated with annual growth increment and resistance to pulsed electric current. In defoliated trees, wound area was highly correlated with starch content of the roots; trees with lower starch content had larger wounds.
A simple, rapid giemsa staining technique for routine study of tree chromosomes
Authors: Karnosky David F. , Setliff Edson C.
Published: May 2008

A giemsa staining technique for rapidly and simply examining tree chromosomes is presented. Somatic chromosomes of two hardwood and two coniferous tree species were successfully stained using the technique.
Biennial strobilus production in balsam fir: a review of its morphogenesis and a discussion of its apparent physiological basis
Authors: Powell G. R.
Published: May 2008

A pattern of alternate-year production of strobilus buds and latent lateral buds occurred on bearing shoots in the reproductive zones of the crowns of balsam fir (Abiesbalsamea (L.) Mill.) trees. The timing of all growth events on such shoots and the relative sizes and numbers of organs produced provided a reasonable physiological (source–sink) basis for the biennial production of strobili in this species.
Effects of the fungal hyperparasite Colletotrichumgloeosporioides of dwarf mistletoe (Arceuthobiumamericanum) on young lodgepole pine
Authors: Muir John A.
Published: May 2008

Dwarf mistletoe (Arceuthobiumamericanum Nutt. ex. Engelm.) infected by the fungus Colletotrichumgloeosporioides Penz. sensu von Arx was examined in two areas of young lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) in southwestern Alberta. The fungus infected 35% and 75% of the dwarf mistletoe plants, 6% and 54% of the aerial shoots, and 7% and 8% of the berries in the respective areas. The number of dwarf mistletoe berries and maximum shoot lengths of dwarf mistletoe plants were significantly reduced by the fungus, and dead plants were more frequent than in areas where the fungus was absent. However, numbers of new dwarf mistletoe plants were not significantly reduced by the fungus. Evidently future increase in numbers of dwarf mistletoe plants and eventual damage to young lodgepole pine in the areas will not be significantly decreased by the fungus.