bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrification in undisturbed mixed hardwoods and manipulated forests in the southern Appalachian Mountains of North Carolina, U.S.A.
Authors: Montagnini F. , Haines B. L. , Swank W. T. , Waide J. B.
Published: April 2011

This paper summarizes data on nitrification at the Coweeta Hydrologic Laboratory, in the southern Appalachian Mountains of North Carolina, U.S.A., focusing on effects of watershed treatment and vegetation type. At Coweeta, as at other United States sites, oak–hickory forests gave the lowest nitrification potentials. Nitrification potentials and nitrifier numbers were lower in oak–hickory forests of undisturbed watersheds than in disturbed watersheds. Nitrification potentials were also low in a white pine plantation, although higher than in other pine forests in the United States. In a regenerating clear-cut and in a 17-year-old successional forest at Coweeta, nitrification potential was higher in dense stands of black locust (Robiniapseudoacacia L.) than in areas where black locust was absent. In the undisturbed forests at Coweeta, low nutrient availability probably limits the size of nitrifier populations; the influence of soil pH on nitrification was unclear. In the disturbed forests, nitrification is apparently controlled by the availability of ammonium nitrogen and other nutrients.
The control of adventitious root production in tissue-cultured Douglas-fir
Authors: Mohammed G. H. , Patel K. R. , Vidaver W. E.
Published: April 2011

Rooting percentage and root number in tissue-cultured Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were influenced by the rooting substrate, the concentration of sucrose and boron in the rooting medium, shoot height, and shoot generation. Peat–perlite was a better substrate than agar, producing 70% compared with 0% rooted shoots, respectively. On peat–perlite, cell divisions were organized and were associated with tracheid nests, whereas on agar proliferation was unorganized and not restricted to the nests. A sucrose concentration of 4% was optimal for the production of nodular or rooted shoots. At 4% sucrose and 3 mg •L−1 boric acid, 100% of the shoots rooted, and the mean root number was 11. Rooting percentage and root number were significantly higher with shoots that were 3 cm tall than 2 or 1 cm tall shoots. Finally, it was found that shoot responses were more rapid in third and fourth generation shoots than in second generation shoots. At least 80% were rooted or nodular after 4 weeks, compared with only 36% from the second generation.
The effect of antibiotics on elongation and callus and bud formation from embryonic tissue of Piceaglauca
Authors: Ellis David D. , Lazaroff Wayne R. , Roberts Dane R. , Flinn Barry S. , Webb David T.
Published: April 2011

Strategies for the selection of transformed cells and the counterselection (clearing) of Agrobacterium in genetic engineering requires a balance between the selection pressures and the normal morphogenetic response of transformed tissue. In this paper, we report the effect of antibiotics used for plant transformation studies on the elongation and induction of buds from embryos and the induction of callus from seedling tissue of Piceaglauca. Carbenicillin, ampicillin (500 and 750 μg/mL), and cefotaxime (250 and 500 μg/mL) are used to clear the invitro environment of bacteria and have little effect on the elongation or bud formation from P. glauca embryos. Concentrations of hygromycin greater than 1 μg/mL and kanamycin greater than 10 μg/mL inhibited elongation, whereas concentrations of kanamycin greater than 5 μg/mL totally inhibited adventitious bud formation, callus formation, and caused seedling mortality. At concentrations as low as 1 μg/mL, kanamycin decreased adventitious bud formation by greater than 50%. These results suggest that effective selection of transformants expressing marker genes can be performed using relatively low concentrations of kanamycin or hygromycin.
Development of a new chemical method for distinguishing between Betulapendula and Betulapubescens in Sweden
Authors: Lundgren L.N. , Pan H. , Theander O. , Eriksson H. , Johansson U. , Svenningsson M.
Published: April 2011

High performance liquid chromatography (HPLC) analytical studies of inner bark extractives from a large number of silver birch (Betulapendula Roth) and hairy birch (Betulapubescens Ehrh.) trees revealed the diarylheptanoid glucoside platyphylloside to be present at high levels in B. pendula (20–60 mg/g dry bark) and at low levels in B. pubescens (≤ 0.5 mg/g dry bark). Based on these observations, a new simple and accurate precipitation method to distinguish between B. pendula and B. pubescens has been developed. In a solution of 2,4-dinitrophenylhydrazine, platyphylloside immediately forms an orange precipitate. A similar precipitate is also produced when a piece of B. pendula inner bark is kept for 1 h at room temperature in the same solution. However, no precipitate forms when a sample from B. pubescens is used. The diagnostic value of morphological characters was assessed by comparing the results of species determinations made on a large number of trees (> 1600), both juvenile and mature, using the morphological and the new chemical method. For birches younger than 20 years there was 100% agreement between the two methods. However, in some mature birch stands with the two species mixed and ages over 40 years, up to 20–30% of the trees were incorrectly identified to species using morphological characters. Results from tests using the precipitation method on birch species, varieties, forms, and hybrids were reported.
Attrition in Swedish forestry work from 1986 to 1990: extent and causes
Authors: Lidén Ewa
Published: April 2011

The results in this paper are based on a combined quantitative and qualitative study of persons who have quit forestry jobs in Sweden. Quitting a job can be voluntary or forced. The aim of the study was to determine the rate of attrition during the period 1986–1990 and describe the reasons why some quit before the age of retirement. In total, 267 persons answered a questionnaire and 15 were interviewed personally. The respondents were categorized as former company employees, former contractor employees, and former contractors. The results showed that workers employed by forestry enterprises quit at a higher rate than the industrial average for Sweden. In contrast, the termination rate of contractors and their employees was lower than the industrial average. The most often cited reason for quitting was health complaints. Former contractor employees quit mainly because they were dissatisfied with their salary or because of work scarcity. The contractors cited financial reasons to the same high extent as health complaints. As many as 42% of all terminations were voluntary.
Application of a chloroplast DNA marker in seed orchard management evaluations of Douglas-fir
Authors: Stoehr M U , Orvar B L , Vo T M , Gawley J R , Webber J E , Newton C H
Published: April 2011

We evaluated pollen contamination, supplemental mass pollination efficacies, and natural selfing in a Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) clonal-row seed orchard using a genetic marker on the paternally inherited chloroplast (cp) genome. A primer pair for the polymerase chain reaction amplification of a variable region on the cpDNA in Douglas-fir was developed. The amplified DNA product was highly variable in size, yielding 13 different haplotype bands from 20 orchard genotypes growing in the clonal-row seed orchard. Observed band sizes ranged from 859 to 1110 base pairs (bp). To estimate variation levels in the orchard background pollen pool, 96 assayed genotypes from surrounding stands gave rise to 36 different haplotypes, ranging from 367 to 1119 bp in size, resulting in a gene diversity estimate of 0.91. Most orchard clones' haplotypes were also present in the background. After adjusting for the presence of orchard-type haplotypes in the background, contamination was found to be 40%. Natural selfing in six individual clones ranged from 0 to 19% with an average of 6%. Supplemental mass pollination efficacy was estimated to be 55%, ranging from 39 to 73%, depending on the maternal clone and flowering phenology. This DNA marker proved to be very useful in assessing seed orchard mating dynamics and orchard management efficacies for Douglas-fir.
Short-term effect of restoration on vegetation change and methane emissions from peatlands drained for forestry in southern Finland
Authors: Komulainen Veli-Matti , Nykänen Hannu , Martikainen Pertti J , Laine Jukka
Published: April 2011

Methane (CH4) fluxes from fixed sample plots in a minerotrophic fen and an ombrotrophic bog in southern Finland were measured by using a static chamber technique 1 year before and 2 years after a rewetting treatment. Methane emissions rose with rising water table after rewetting from 0.1 to 2.1 g ·m-2 ·a-1 at the fen site and from 0.8 to 4.6 g ·m-2 ·a-1 at the bog site but remained at a lower level than emissions from similar pristine site types. At the fen site the emissions were related to the short-term succession of cottongrass (Eriophorum vaginatum L.). Emissions showed high spatial and temporal variation with high emission peaks at the bog site. Temporal fluctuation of the emissions during the measurement season (from the end of May to the end of September) was correlated with peat temperature, while the seasonal fluxes were dependent on the moisture conditions in different microsites.
Effect of nitrogen availability on the growth and phytochemistry of hybrid poplar and the efficacy of the Bacillus thuringiensis cry1A(a) d-endotoxin on gypsy moth
Authors: Kleiner Karl W , Raffa Kenneth F , Ellis David D , McCown Brent H
Published: April 2011

We tested the hypothesis that soil nitrogen availability could alter the efficacy of the cry1A(a) d-endotoxin of Bacillus thuringiensis (B.t.) through variation in phytochemistry. Extracts of the cry1A(a) d-endotoxin were administered to second-instar gypsy moth (Lymantria dispar) larvae on foliage from hybrid Populus plants (clone NC5339) grown in sand culture for 10 weeks with 10, 25, 50, and 120 ppm nitrogen applied as a modified Hoagland's solution. Poplar biomass increased with increasing nitrogen availability. Net rates of photosynthesis responded positively to increased nitrogen availability in fully expanded leaves only. Concentrations of condensed tannins and salicortin increased as nitrogen availability decreased. Larvae feeding on fully expanded leaves encountered twice the condensed tannin concentration but experienced less than half the mortality of larvae feeding on halfway expanded leaves. Low nitrogen availability increased larval mortality and prolonged the development times of second-instar larvae feeding on both halfway and fully expanded leaves treated with the B.t. cry1A(a) d-endotoxin. Nitrogen concentrations in fully expanded leaves were negatively correlated with larval mortality. Relationships among larval performance, condensed tannins, and phenolic glycosides were weak or nonexistent. These results suggest that the efficacy of the B.t. d-endotoxin will be enhanced when short-rotation poplar plantations are grown on soils of low fertility, but this protection will be at the expense of biomass productivity.
Contrasting patterns of biomass allocation in dominant and suppressed loblolly pine
Authors: Naidu Shawna L , DeLucia Evan H , Thomas Richard B
Published: April 2011

We investigated above- and below-ground biomass allocation and allometric relationships of canopy dominant and suppressed loblolly pine (Pinus taedaL.) trees from a range of diameters at breast height (DBH = 3.5-35.6cm) to determine if shifts in allocation may influence the growth and persistence of suppressed trees in the understory. Using mass and volume conversions from harvested trees (15 dominant and 15 suppressed), we developed regressions to predict total and component biomass from DBH. Bole, branch, needle, and total mass differed between dominance categories (ANCOVA, P < 0.10). For a representative size (15cm DBH), dominant trees allocated 63.4, 13.2, 11.3, and 12.0% of biomass to bole, branch, needle, and root tissue compared with 75.9, 6.7, 5.6, and 11.7% for suppressed trees. At any given DBH, suppressed trees were also taller than dominant trees and had a greater porportion of heterotrophic (bole plus branch plus root mass) to autotrophic (needle mass) tissue. Percent carbon and nitrogen of tissues did not differ between dominance categories. Unlike the increased investment in leaf area observed for seedlings and saplings of shade-tolerant species, suppressed loblolly pine increased allocation to bole mass and height growth. An increase in height for this shade-intolerant species may enable some suppressed individuals to escape competition for light. However, increased allocation to heterotrophic versus autotrophic tissue in suppressed trees may confer a cumulative disadvantage over time because of increased respiratory load.
Determination of relative economic weights for multitrait selection in coastal Douglas-fir
Authors: Aubry Carol A , Adams W T , Fahey Thomas D
Published: April 2011

Relationships between tree traits and tree value for lumber production were investigated. For the purposes of estimating relative economic weights for use in multitrait selection in coastal Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii), tree height, diameter at breast height, and branch diameter were measured on 164 trees (ages 36-66 years). Increment cores from a subsample (92) of these trees were assayed by X-ray densitometry to determine wood density. Bole volume was derived by summing the log volumes of all logs from each tree. Value of lumber recovered from each tree was determined in a separate mill study using both visual and machine stress rated (MSR) grading rules. Multiple linear regression was used to relate tree value to the growth and wood quality traits. Stem volume and branch diameter significantly influenced tree value under visual grading, with relative economic weights of 0.06dm3 and -5.22cm, respectively. Wood density significantly influenced tree value under MSR grading (relative economic weights: 0.06dm3, -6.69cm, and 0.06kg/mdm3, respectively), where lumber strength is measured more accurately. These regression coefficients can be used directly as economic weights in selection indices.
Distinguishing between change and growth in forest surveys
Authors: Williams Michael S
Published: April 2011

Much of the research in forest inventory has focussed on the generation of estimates of forest attributes at particular times and estimating how these attributes change over time. In descriptions of this work in recent decades, the terms forest growth and forest change have been used interchangeably. In this paper, the distinction between growth and change is defined and an example is given illustrating the differences between the two. Unbiased estimators of both processes are presented, and a simulation study with an artificial population is used to illustrate their properties. The results of the simulation study indicate that estimates of forest growth tend to be slightly more efficient than estimates of forest change.
Radial tree-growth modelling with fuzzy regression
Authors: Boreux J J , Gadbin-Henry C , Guiot J , Tessier L
Published: April 2011

A so-called fuzzy linear regression is used in dendroecology to model empirically tree growth as a function of a bioclimatic index representing the water stress, i.e., the ratio of actual evapotranspiration to potential evapotranspiration. The response function predicts tree growth as (fuzzy) intervals, narrow in the domain where the bioclimatic index is most limiting and becoming progressively larger elsewhere. The method is tested with a population of Pinus pineaL. from the Provence region in France. It is shown that fuzzy linear regression gives results comparable with those obtained using a linear response function. The interval of credibility given by the fuzzy regression suggests that more precise expected growth is obtained for high water stress, which is typical of Mediterranean climate. Fuzzy linear regression can be also a method to test different hypotheses on several potential predictors when any further experimental approach is quite impossible as it is for trees in their natural environment. To sum up, fuzzy regression could be a first step before the construction of a kind of growth simulator adapted to different environments of a given species. In environmental sciences, the fuzzy response function thus appears to be an approach between the mechanistic and the statistical descriptive approaches.
The use of laboratory measurements to predict nitrogen mineralization and nitrification in Pinus radiata plantations after harvesting
Authors: Carlyle J Clive , Nambiar EK Sadanandan , Bligh Mark W
Published: April 2011

We tested whether laboratory estimates of net N mineralization and nitrification (subsequently termed N mineralization and nitrification) could be used to predict these processes in the field after harvesting nine Pinus radiata D. Don. plantations. Laboratory rates of N mineralization and nitrification were measured by aerobic incubation (20°C) of intact cores. Annual rates of these processes in the field were measured using a sequential coring procedure. Rates of N mineralization in the laboratory were 1.1-6.6 and 0.019-0.525mg·kg-1·day-1 for forest floor and mineral soil, respectively (nitrification accounted for 6-71 and 8-93% of N mineralization). Annual N mineralization by forest floor in the field was 5.2-23.9kg·ha-1·year-1and was not correlated with N mineralized in the laboratory. Annual N mineralization in mineral soil in the field was 16-74kg·ha-1·year-1and was highly correlated (r2 = 0.97) with N mineralized in the laboratory. Annual nitrification in forest floor in the field ranged from 3 to 45% of annual N mineralization, and in mineral soil from 4 to 27%, both were correlated with relative nitrification measured in the laboratory.
An application of Bayesian techniques to the genetic evaluation of growth traits in Eucalyptus globulus
Authors: Soria F , Basurco F , Toval G , Silió L , Rodriguez M C , Toro M
Published: April 2011

A Bayesian procedure coupled with Gibbs sampling was implemented to obtain inferences about genetic parameters and breeding values for height and diameter of 7-year-old Eucalyptus globulus Labill. is described. The data set consisted of 21 708 trees from 260 open-pollinated families taken from 10 different Australian provenances, from one Spanish population, and from two clones. The trees are distributed over eight sites in the south of Spain, with 20 blocks per site. Data were corrected for heterogeneity of phenotypic variances between blocks. In the analysis, a self-pollination rate of 30% for the open-pollinated families is assumed in the relationship matrix. The posterior means (and standard deviations) of the heritabilities of height and diameter and the genetic and phenotypic correlation were 0.217 (0.014), 0.128 (0.084), 0.768 (0.028), and 0.799 (0.003). Results from the standard restricted maximum likelihood method were 0.173, 0.113, 0.759, and 0.798, respectively. Most of the discrepancy in heritability estimates from both methods can be attributed to the adjustement of residual maximum likelihood estimates to the assumed self-pollination rate, which ignores the presence of clones in the trial. The effect of the method of prediction of breeding values (best linear unbiased prediction or Bayesian techniques) on the genetic superiority of the selected trees was not important. Differences in breeding value among provenances and among families were evidenced for both traits.
Cultural, geographical, and sectoral refinements to measures of forest industry dependence
Authors: Korber D , Beckley T , Luckert M , White W
Published: April 2011

Economic base analysis is a limited but useful tool for measuring forest dependence. It cannot measure the full range of forest values (e.g., subsistence, amenity, bequest, and existence values). However, economic base analysis utilizes widely available census data to provide accurate measures of communities dependent on industrial forest activity. This analysis includes Indian reserves and rural census subdivisions previously excluded in studies of economic base dependence. Economic base dependence measures are further improved by including a transfer payment sector. This paper presents findings of forest industry dependence measures using 1991 census data. Results show that including Indian reserves and other rural census subdivisions in the analysis increases the number of forest industry dependent places and population in the Prairie Provinces. The addition of the transfer payment sector to the economic base provides a more comprehensive account of the sources that contribute to the economic diversity of rural locations. These geographical and sectoral refinements to economic base calculations result in a more accurate accounting of forest industry dependence.
Regeneration from seed of six tree species in the interior cedar-hemlock forests of British Columbia as affected by substrate and canopy gap position
Authors: Wright Elaine F , Coates K Dave , Bartemucci Paula
Published: April 2011

Canopy gap size can play a major role in determining composition of tree regeneration after disturbance. The effect of different positions within gaps and within the intact forest has received less study. We seeded six tree species onto two substrates (organic and undisturbed moss) in three positions along a north-south gradient within eight replicate 600-m2 canopy gaps and in the intact forest south of each gap (the gap positions), in 1995 and 1996. Emergence of all species was strongly affected by gap position, seedbed substrate, and year, but there was little evidence of partitioning by gap position among the species. Average emergence was higher in the shady southern position in gaps and within the intact forest and significantly higher on organic than undisturbed moss substrates (with the exception of Abies lasiocarpa (Hook.) Nutt., which showed no preference for seedbed). Seedling survival was greatest for all species in the south end of the gap, where soil moisture remained highest and light levels of approximately 20% full sun were adequate for survival. A species trade-off was observed in the understory of the intact forest, where differential survival based on shade-tolerance ranking occurred. To predict regeneration success in these forests, for either silvicultural purposes or to permit a better understanding of community dynamics and succession, it is important to consider the influence of position inside and outside of gaps and the nature of the seedbed substrate.
Throughfall chemistry of an ecotonal forest on the edge of the Great Plains
Authors: Hamburg Steven P , Lin Teng-Chiu
Published: April 2011

Throughfall concentrations and fluxes were examined in an oak-hickory forest on the western ecotone of the eastern deciduous forest biome during 1989. Throughfall chemistry from event-based sampling of three stands was compared with the chemistry of incident precipitation. During the dormant season, only one of eight elements had significantly higher flux under the forest canopy relative to precipitation. During the growing season, six elements had significantly higher flux in throughfall relative to incident precipitation, and nitrogen had a significantly lower flux. Rates of dry deposition of pedogenically derived elements were high relative to forests further to the east, while rates of deposition of anthropogenically derived elements were low in comparison to these same forests. About 50% of the inorganic nitrogen in precipitation was taken up by the canopy, the highest value reported for an eastern deciduous forest. There were significant differences in throughfall chemistry among the three stands, possibly due to differences in canopy structure and (or) species composition. Multiple regression analysis of the throughfall patterns showed significant correlations of throughfall chemistry with the length of the antecedent dry period and rainfall quantity for all elements examined.
Aboveground modular component responses to intraspecific competition within density-stressed black spruce stands
Authors: Newton P F , Jolliffe P A
Published: April 2011

A broad range of measures of aboveground growth were used to assess whether competition occurs by processes of resource depletion or resource preemption within monospecific, even-aged, density-stressed, and spatially heterogeneous black spruce (Picea mariana (Mill.) BSP) stands. The assessments proceeded by evaluating the relationships between relative growth and partitioning indices of individual subject trees and directional-specific indices of cumulative competition. Significant directional-specific asymmetrical relationships between subject trees and their local competitors were found, indicating the occurrence of competition by resource preemption. All measures of growth, however, did not respond to directional-specific competition to the same degree. Larger responses, characterizing the response of black spruce trees to increasing competition from their larger neighbours, involved decreased branch production and changes in foliar morphology. Such adaptive, plastic responses in phenotype, combined with lesser responses of foliage production and nutrient concentrations, suggest a strategy used by black spruce to compete within density-stressed populations situated on nutrient-limiting sites: decreased allocation of resources to nonphotosynthetic components, maintenance of the photosynthetic apparatus through adjustments in foliage morphology, and nutrient conservation through foliage retention.
Multivariate analysis of allozymic and quantitative trait variation in Alnus rubra: geographic patterns and evolutionary implications
Authors: Hamann Andreas , El-Kassaby Y A , Koshy M P , Namkoong G
Published: April 2011

Frequency data from six polymorphic allozyme loci and measurements of six quantitative traits were used to examine geographic differentiation among 65 British Columbia provenances of red alder (Alnus rubra Bong.). Principal components analysis showed that variation in quantitative traits can be reduced to two underlying dimensions, one representing general vigor including the termination of the growing period and the other being the start of the growing period. Canonical correlation analysis among quantitative traits, allozyme frequencies, and geographic variables revealed complex associations of quantitative traits with the latitude, distance to the coast, and elevation of the seed source. There were no significant correlations among allozyme frequencies and quantitative traits, but the frequency of the most common allele at most loci decreased with latitude. Further, cluster analysis based on Nei's genetic distance revealed a strong differentiation among island and mainland provenances at one allozyme locus. This differentiation can be interpreted as a result of migration from two different refugia since the last glaciation. The island populations presumably originate solely from isolated coastal refugia west of the Cordilleran ice sheet, while mainland populations were also recruited from areas south of the ice.
Forest floor chemistry under seven tree species along a soil fertility gradient
Authors: Vesterdal Lars , Raulund-Rasmussen Karsten
Published: April 2011

Forest floor chemistry, i.e., C/nutrient ratios, pH, and element contents, were determined in stands of two deciduous species and five conifer species replicated at seven sites along a soil fertility gradient. There were consistent differences between forest floors of the tree species. Lodgepole pine (Pinus contorta Dougl.) forest floors had highest C/nutrient ratios, lowest pH, and the greatest element contents, whereas oak (Quercus robur L.) forest floors had low C/nutrient ratios and the lowest element contents of all species. Differences in forest floor C/nutrient ratios, pH, and element contents between sites of low nutrient status and sites of intermediate to high nutrient status were also great. Forest floor pH was related to mineral soil pH, and C/P, C/Ca, and C/K ratios were related to mineral soil nutrient concentrations. Forest floor C content was negatively related to most mineral soil fertility variables and was closest related to texture, pH, and concentrations of P and Ca. The C content of lodgepole pine and oak forest floors tended to be less affected by the soil fertility gradient. The results suggest that C storage and immobilization of nutrients in forest floors may be managed along an extensive soil gradient by selection of the proper tree species.
Green leaf volatiles disrupt and enhance response to aggregation pheromones by the ambrosia beetle, Gnathotrichus sulcatus (Coleoptera: Scolytidae)
Authors: Deglow E Keith , Borden John H
Published: April 2011

Experiments were conducted to test the hypothesis that green leaf volatiles (GLVs) abundant in herbaceous plants and angiosperm trees, affect the response by the conifer-infesting ambrosia beetle, Gnathotrichus sulcatus (LeConte), to pheromone-baited multiple-funnel traps. A blend of four green leaf alcohols, 1-hexanol, (E)-2-hexen-1-ol, (Z)-2-hexen-1-ol, and (Z)-3-hexen-1-ol, each released at ca. 4 mg/24 h, combined with a blend of two green leaf aldehydes, hexanal and (E)-2-hexenal, each released at ca. 13 mg/24 h, reduced trap catches to levels no different from those to unbaited control traps for both sexes. Release of the green leaf alcohols, alone or in all possible binary and ternary blends revealed additive rather than synergistic disruptive effects. Only (E)-2-hexen-1-ol was active alone. Binary and ternary blends reduced trap catches 60-88%, and 80-93%, respectively. No blend was superior, demonstrating redundancy in the disruptive effect. Released together, the two green leaf aldehydes enhanced trap catches; (E)-2-hexenal alone caused a weak enhancement. A summary of known responses by 11 scolytids to GLVs revealed variations between and within species in bioactive compounds and their effect. Disruptive GLVs offer promise alone or with other compounds as forest product protectants against ambrosia beetles.
Ten-year tree mortality following a jack pine budworm outbreak in Saskatchewan
Authors: Volney W Jan A
Published: April 2011

The fate of jack pine (Pinus banksiana Lamb.) trees growing in a variety of stand conditions was assessed annually for a decade following an outbreak of jack pine budworm (Choristoneura pinus Freeman) in central Saskatchewan. Mortality was clearly associated with the severity and damage sustained by the trees during the second year of the defoliation episode. The pattern of mortality was remarkably similar among stands that originated in decades that spanned 60 years. Mortality rates were highest in stands that originated in the 1890s and were lowest in stands of the most recent origin (1940s). Defoliation severity, the length of dead top, diameter at breast height, and relative tree height expressed as a standard normal variable accounted for 94% of the variability in survival time. A nonparametric proportional hazards model was developed to evaluate the relative risk of individual trees dying. Defoliation is an important process in determining stand density, basal area, and volume after juvenile stand development is complete. The results presented suggest a novel method to determine the hazard of trees in stands and thus assess the vulnerability of stands to future budworm attack.
Site index, site quality, and foliar nutrients of trembling aspen: relationships and predictions
Authors: Chen Han YH , Klinka Karel , Kabzems Richard D
Published: April 2011

To examine the relationships between trembling aspen (Populus tremuloides Michx.) productivity, environmental attributes, and foliar nutrients and to make accurate predictions of trembling aspen productivity, we sampled 60 naturally established, fire-originated, and even-aged trembling aspen stands in northern British Columbia. Trembling aspen site index significantly varied with latitude, elevation, aspect, slope position, edatopes, some forest floor and mineral soil physical and chemical properties, and concentrations of some foliar nutrients. To predict site index, we developed multiple linear regression models using climatic variables, topographic properties, edatopes, soil physical and chemical properties, or foliar nutrients as predictors. Model accountability for variation of site index differed in decreasing order from soil model, climatic model, forest floor model, foliar nutrient model, edatope model, topographic model, to mineral soil model. Examined by the test data set, all models were unbiased, but they had different levels of precision in prediction in decreasing order from edatope model, soil model, forest floor model, mineral soil model, foliar nutrient model, climatic model, to topographic model. The soil and foliar nutrients models may provide insight into ecosystem processes, but the models using climatic variables and topographic properties or edatopes as predictors are recommended for predicting trembling aspen site index.
Apical mitotic activity and growth in clones of Norway spruce in relation to cold hardiness
Authors: Westin Johan , Sundblad Lars-Göran , Strand Martin , Hällgren Jan-Erik
Published: April 2011

Seasonal development of apical mitotic activity and growth in three clones of Norway spruce (Picea abies (L.) Karst.) of the same age and origin but with differences in accumulated height growth and cold hardiness were investigated. The clones showed no consistent difference in mitotic index (MI), either in period or in general levels. The response of MI to temperature differed in spring and fall. Differences in cold hardiness between the clones was not directly coupled to differences in MI. Diameter growth ended earlier in one clone than in the other two clones, and this clone also produced lower numbers of stem units in both lateral and leader shoots. Cessation of diameter growth showed no relation to the duration and level of apical MI. The tallest clone had, as a combined effect of both size and number of stem units, significantly longer leader shoots than the other two clones. The greater leader shoot growth of the tallest clone relative to the other two clones during 1987-1996 was also most prominent after years with sudden drops in fall minimum temperatures to below ca. -12°C (median; interval: -11 to -13°C), following several weeks with mean temperatures above 3°C.
Effect of early spring birch bud type on post-thaw regrowth after prolonged cryostorage
Authors: Ryynänen Leena
Published: April 2011

Early spring buds of silver birch (Betula pendula Roth), collected with and without a female catkin in the middle of April, were cryopreserved using slow cooling followed by immersion in liquid nitrogen at -196°C for 8 days, 6 months, 1 year, 3 years, or 5 years. After fast thawing the buds were cultured in vitro according to the published protocol. The regrowth ability of the two types of buds was different. The regrowth of vegetative buds without a female catkin was good after all the cryopreservation times. There was a significant decrease in the regrowth ability of buds growing in the axil of a female catkin compared with the corresponding unfrozen controls after 1 year in cryostorage. In addition to the effect of the presence of a catkin on the regrowth ability, the late collecting time of the buds also probably decreased the regrowth and regrowth rates of both types of bud. The regrowth rates of buds without a catkin were 66, 67 and 24% after 1, 3, and 5 years of cryostorage, respectively, while those of buds with a catkin were 13.5, 32, and 2.6%, respectively.
Pin cherry effects on Allegheny hardwood stand development
Authors: Ristau Todd E , Horsley Stephen B
Published: April 2011

Pin cherry (Prunus pensylvanica L.) develops an early height advantage over associated species. Data from three long-term studies, extending up to 70 years after complete overstory removal, were used to evaluate the effects of pin cherry density on associates. Survival of seedling-origin stems of black cherry (Prunus serotina Ehrh.), red maple (Acer rubrum L.), and sugar maple (Acer saccharum Marsh.) at age 15 decreased as the density of pin cherry >1.5 m tall at age 3 increased. The regression of pin cherry with black cherry was particularly strong (R2 = 0.632). Height of the tallest black cherry and white ash (Fraxinus americana L.) at age 15 also decreased. If the density of pin cherry at age 3 was > 1 stem > 1.5 m tall per 0.0004 ha (high density), the number of black cherry fell below full stocking at age 15. When pin cherry occurred in high density, it lived longer than when it occurred at low density (< 1 stem > 1.5 m tall per 0.0004 ha). High pin cherry density early in stand development delayed the time when shade-intolerant and shade-intermediate species reached a stable proportion of the total basal area. In the long term, pin cherry reduced stand diameter and volume growth, particularly of black cherry.
Influence of soil type on mass loss and nutrient release from decomposing foliage litter of beech and Norway spruce
Authors: Vesterdal Lars
Published: April 2011

Mass loss and nutrient release from decomposing foliage litter of beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) were studied at three sites along a soil fertility gradient. The influence of soil type on initial litter quality and on decomposition was separated by reciprocal transplantation of litter among soil types using the litterbag technique. Decomposition of beech litter was influenced by both initial litter quality and incubation site. Mass loss in beech litter was positively influenced by soil nutrient status. Decomposition of Norway spruce litter was not affected by initial litter quality, and the positive influence of a nutrient-rich soil environment on decomposition was weak. Nutrient release in litters of both tree species was greatly affected by soil type through its influence on initial litter quality, as nutrient release was positively related to initial nutrient concentrations. Nutrient release was less affected through the soil environment, as it only influenced release of some nutrients, and the differences were not consistently related to soil nutrient status or mass loss. The influence of soil type on decomposition differed among the two tree species, suggesting that it may be more significant in species that produce relatively higher quality litter.
Fine-scale patterns of leaf litterfall and nitrogen cycling in an old-growth forest
Authors: Ferrari James B
Published: April 2011

Spatial patterns of litterfall and soil nitrogen (N) mineralization were investigated in an old growth hemlock-hardwood forest to test the hypothesis that the lignin/N ratio of litterfall is negatively correlated with soil N availability. Litterfall was measured at 50 small subplots on a 7.2-ha mapped plot in Sylvania Wilderness Area, Michigan, where there is pronounced patchiness of species in the canopy. Nitrogen mineralization and nitrification were measured concurrently at the subplots using buried-bag incubations. Total aboveground litterfall was 3723 kg·ha-1 per year with leaf litterfall contributing 69% of the total, and N mineralization was 68.0 kg·ha-1 per year. The lignin/N ratios of leaf litter and total litterfall were negatively correlated with soil N mineralization and nitrification at the 50 subplots. Nitrogen mineralization rates, especially percent nitrification, were higher where basswood and sugar maple litterfall dominated and lower where hemlock litterfall was high, demonstrating the importance of litterfall and leaf litter chemistry to soil N pattern on a fine spatial scale. The effect of leaf litter chemistry on soil N may be a positive feedback mechanism that maintains the landscape-scale canopy mosaic at Sylvania.
Pathology of conifer seed and timing of germination in high-elevation subalpine fir and Engelmann spruce forests of the southern interior of British Columbia
Authors: Zhong Jianwen , van der Kamp Bart J
Published: April 2011

Unstratified seed of Engelmann spruce (Picea engelmannii Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) in nylon mesh bags was placed on various natural and disturbed forest floor seed beds in the Engelmann Spruce - Subalpine Fir Zone in the southern interior of British Columbia in September 1995 and recovered just before snow melt in June 1996. Fifty-two and 86% of the viable spruce and fir seed, respectively, had germinated before snowmelt. Germination under snow may be an adaptation of these high-elevation species to short cool growing seasons. Seed viability at recovery was significantly lower on undisturbed forest floor seed beds (spruce, 13%; fir, 12%) than on exposed mineral soil (spruce, 57%; fir, 42%). Viability of seed placed on nurse logs was 38 and 23% for spruce and fir, respectively. Isolation from ungerminated seed yielded a Rhizoctonia sp., an as yet unidentified black mold at high frequencies, and several other seed pathogens at low frequency. Multiple linear regression of the frequency of isolation of Rhizoctonia and black mold on seed viability was highly significant for both tree species. Seed pathogens appear to cause a major loss of seed and seedlings in these forests, and this may explain both the common occurrence of regeneration on nurse logs and the requirement of mineral soil seed beds for adequate regeneration.
Natural regeneration after harvest and residue treatment in a mixed conifer forest of northwestern Montana
Authors: Shearer Raymond C , Schmidt Jack A
Published: April 2011

In 1974, two clearcuts, two shelterwoods, and two sets of eight group selections (equally divided between two elevation zones) were harvested on the Coram Experimental Forest in northwestern Montana. Four levels of tree and residue utilization were compared. Moist fuels on approximately half of each area were poorly burned by prescribed fires in September 1975. Natural regeneration on these treatments was compared in 1979, 1987, and 1992. Regeneration of western larch (Larix occidentalis Nutt.) began in 1975 on soil exposed during yarding of logs and continued mostly in 1977 and 1979 on these scarified sites and other burned areas. Competing vegetation curtailed establishment of larch seedlings much past 1979 on these sites. Few Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) regenerated before 1979 but aggressively established through 1992. Engelmann spruce (Picea engelmannii Parry) and subalpine fir (Abies lasiocarpa (Hook.) Nutt) regeneration began in 1979 and is increasing slowly throughout the area. Western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western red cedar (Thuja plicata Donn.) also slowly regenerate moister areas of the lower elevation units.
Tree spatial patterns and stand development along the pine-grassland ecotone in the Colorado Front Range
Authors: Mast Joy Nystrom , Veblen Thomas T
Published: April 2011

Patterns of stand development may be interpreted from spatial analyses, based on variables such as tree age and size, together with past records of climate and disturbance. In the present study, our objective is to examine spatial patterns of tree age and size to determine if they are consistent with the episodic pattern of tree regeneration proposed for ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) and expected changes in tree spatial patterns as cohort patches age. According to our hypothesis, internal patch structure should become less clumped as single cohort patches age due to self-thinning, with few trees attaining dominance in a small patch. In this study, tree spatial patterns in 16 stands of P. ponderosa in the Colorado Front Range are described and related to patterns of stand development. Analytical methods included Ripley's K(t) (a univariate statistic of tree spatial distribution), Ripley's K12(t) (a bivariate statistic of spatial association), and Moran's I (a measure of spatial autocorrelation). Spatial patterns imply establishment of patches of pines followed by self-thinning. Continued stand development results in strong size hierarchies as manifested by stronger spatial autocorrelation of tree age than tree size. Hence, pines exhibit a strong size class hierarchy developed within an even-aged patch.
An individual-tree basal area growth model for black spruce in second-growth peatland stands
Authors: Hökkä Hannu , Groot Arthur
Published: April 2011

A basal area growth model was developed to predict the growth of individual trees in second-growth black spruce (Picea mariana (Mill.) BSP) stands on northeastern Ontario peatlands. The data were derived from stem analysis trees collected in 1985 and 1986 from stands harvested 47-68 years earlier. For a period starting from the date of data collection and going back to 10 years from the harvesting, tree basal area growth, diameters, and stand characteristics were retrospectively calculated at 5-year intervals. To estimate previous mortality, self-thinning relationships for black spruce were applied. In the model, 5-year basal area growth of a tree was expressed as a function of tree diameter, stand-level competition, tree-level competition, and peat thickness. There was considerable change in the growth-size relationship over time. A random parameter approach was applied in model construction to account for the spatial and temporal correlations of the observations. The proposed model explicitly incorporates factors normally included in a "random error" term and, therefore, should provide more sensitive tests of the contributions of the various factors to growth prediction. The estimated model showed only slight bias against the modeling data and the predicted stand basal area development was comparable with that given in other studies.
Leaf area and tree increment dynamics of even-aged and multiaged lodgepole pine stands in Montana
Authors: Kollenberg Cassandra L , O'Hara Kevin L
Published: April 2011

Age structure and distribution of leaf area index (LAI) of even and multiaged lodgepole pine (Pinus contorta var. latifolia Engelm.) stands were examined on three study areas in western and central Montana. Projected leaf area was determined based on a relationship with sapwood cross-sectional area at breast height. Stand structure and LAI varied considerably between individual plots. LAI and stand stem volume increment were significantly higher in multiaged than even-aged stands with the exception of one study area, which had higher volume increment in even-aged stands. Older cohorts and higher canopy strata generally had greater LAI than younger cohorts and lower strata. Ratios of stem volume increment to leaf area were used to assess stand, cohort, and individual tree vigor or growing space efficiency (GSE). Even-aged stands had significantly higher GSEs in individual study areas and overall than multiaged stands. Cohort GSE generally increased with increasing age of the cohort. Stand increment was weakly associated with stand LAI. Individual tree volume increment was strongly related to projected leaf area when stands were divided by age-classes or canopy strata. These results suggest separating these stands into components, such as age classes or canopy strata, and summing predicted increment for each component may provide more accurate prediction of stand increment than using whole-stand LAI.