bluuebunny/crossref_metadata_2025 huggingface dataset:
Height and radial growth trends of Corsican pine in western France
Authors: Lebourgeois François , Becker Michel , Chevalier Richard , Dupouey Jean-Luc , Gilbert Jean-Michel
Published: April 2011

Height and radial growth trends were analysed in Corsican pine (Pinus nigra Arnold ssp. laricio var. Corsicana) plantations in western France. Difference in height growth was tested by comparing the site index of stands established before and after 1950 and the height growth development curves of 13 pairs of young and old stands growing side by side on the same soil type. The site index of the young stands was 20-30% greater than the site index of the old stands. From the period 1921-1991, radial growth increased 45, 31, and 50% in earlywood, latewood (LW) and total ring (TR) area, respectively. The amount of increase depended on cambial age. The LW/TR ratio decreased by 8%. The regional climatic data revealed a significant increase in mean annual temperature of 1.1°C, mean annual minimum temperature (1.5°C), mean summer temperature (2.2°C), and minimum summer temperature (2.3°C) for the period 1950-1997. Because of the negative correlation between summer temperature and ring widths, increased temperature cannot explain the observed increases in growth. Effects of nitrogen inputs, which averaged 6.3 and 11 kg·ha-1·year-1 for bulk and throughfall depositions, respectively; land use history; improvement in silvicultural practices (wider initial spacing, higher thinning); and CO2 fertilization are discussed as possible causes of the observed growth trends.
Using auxiliary information to estimate stand tables
Authors: Green Edwin J , Clutter Michael
Published: April 2011

The problem of estimating stand tables in stands with few sample points is considered. The usual point-sampling estimate of trees per hectare by diameter class is examined, along with two alternative estimators: a precision-weighted composite estimator and a pseudo-Bayes estimator. A large-scale forest inventory is simulated, and stand tables are estimated for each stand with each of the three estimators. Both the composite and pseudo-Bayes estimator appear superior (in terms of mean absolute error and mean squared error) to the usual estimator. The pseudo-Bayes estimator appears to perform the best (with an 80% reduction in mean squared error). This estimator also is easier to use than the composite estimator because it does not require within diameter class variance estimates.
Distribution and severity of white pine blister rust and mountain pine beetle on whitebark pine in British Columbia
Authors: Campbell Elizabeth M , Antos Joseph A
Published: April 2011

A major decline in the abundance of whitebark pine (Pinus albicaulis Engelm.) has recently occurred in the United States, primarily as a result of white pine blister rust (Cronartium ribicola J.C. Fisch. ex Raben.). However, no information on the status of whitebark pine in British Columbia, Canada, was available. We sampled 54 subalpine stands in British Columbia, examining all whitebark pine trees within plots for evidence of blister rust and mountain pine beetle (Dendroctonus ponderosae Hopk.) damage. About 21% of all whitebark pine stems were dead, and blister rust was the most important agent of mortality. Of all living trees sampled, 27% had obvious blister rust infection (cankers), but actual incidence was suspected of being as high as 44% (using all evidence of blister rust). Blister rust incidence and whitebark pine mortality were significantly related to differences in stand structure and the presence of Ribes spp., but relationships with local climate and site variables were absent or weak. The lack of strong relationships with climate suggests favourable conditions for the spread of the disease throughout most of British Columbia. Very little evidence of mountain pine beetle was found. Overall, the prospects for whitebark pine in British Columbia do not appear good; a large reduction in population levels seems imminent.
The effect of temperature on site index in western Canada and Scandinavia estimated from IUFRO Pinus contorta provenance experiments
Authors: Fries Anders , Lindgren Dag , Ying Cheng C , Ruotsalainen Seppo , Lindgren Katarina , Elfving Björn , Karlmats Ulf
Published: April 2011

Site index was calculated for 78 experimental plantations in western Canada and northern Finland and Sweden, representing a wide range of site environments where lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) is considered as a potential afforestation species. The plantations and provenances belong to the International Union of Forest Research Organizations' international provenance testing program, and estimates of site index (projected 50-year height) were based on height growth of recommended provenances. The estimated site indices were used in regression analyses with temperature data and estimated soil fertilities to predict the change in forest production due to a warmer climate, which may follow an expected rise in atmospheric CO2. The influence of temperature was strong and considerably stronger in northern Finland and Sweden than in Canada. The relationships differed between the two continents and between sites located north of 56°N and south of that latitude. Soil fertility had a small but significant influence. Estimates of increases in site index and potential productivity in different scenarios for increases in temperature sum and average July temperatures are given.
Fire spreading experiments on heterogeneous fuel beds. Applications of percolation theory
Authors: Nahmias Jean , Téphany Hervé , Duarte José , Letaconnoux Sophie
Published: April 2011

In the experimental work presented here, fire spread was studied through various laboratory and full-scale models containing different types of combustible and noncombustible materials. We have examined the dynamic behaviour of the flame front and the final state (after extinction) on randomly created heterogeneous zones, both with and without wind. The principal conclusion is that critical thresholds exist, for the ratio between combustible and noncombustible parts, at the transition between nonpropagation and propagation of the fire. This result is common to all types of spreading (with or without wind). The values of the critical thresholds in the nonwind-driven experiments are those of the percolation theory. The critical exponent, obtained for wind-driven experiments, is in accordance with current values suggested by the directed percolation approach.
Sexual recruitment of trees in strip cuts in eastern Canada
Authors: Greene David F
Published: April 2011

I tested a sexual recruitment model that couples equations for seed production, dispersal, and juvenile survivorship using 10 sets of recent strip cuts in Quebec and New Brunswick. The model states that seed production is dependent on basal area and inversely proportional to seed mass, while juvenile survival is directly proportional to seed mass. In consequence, the seed mass effects should (roughly) cancel out, and fecundity should be primarily a function of basal area. Further, the model predicts that species evenness should be more or less the same following strip-cutting. As expected from the model, the single best predictor (r2 = 0.53) of recruitment density was the basal area density (area/area) of the source trees, and all cuts were well stocked. There was a stronger tendency toward a post-harvest increase in species evenness than was expected. Ninety percent of all stems were recruited by the fourth growing season.
The aftermath of tree death: coarse woody debris and the topography in four tropical rain forests
Authors: Gale Neil
Published: April 2011

The relationship of coarse woody debris (CWD) was examined with respect to topography and site in four lowland tropical rain forests in northern Borneo and western Ecuador. In total, 1914 dead trees [Formula: see text]20 cm diameter at breast height were enumerated in 46 ha. The basal area per hectare of dead trees varied strongly with both site and slope position. Dead basal area and its correlate dead tree density increased moving up the topographic gradient from the valleys to the ridges. Site estimates for CWD volume ranged from 96 to 154 m3·ha-1. Mean standing CWD volume was four times higher on the ridge tops (54 m3·ha-1) compared with the valley and cross-terrain areas (both 13 m3·ha-1). In contrast, downed volume did not vary with slope position. The proportions of CWD present as standing wood were two to three times higher in the Bornean sites compared with Hoja Blanca. These topographical and site differences in CWD were linked to differences in mode of tree death as well as the distribution of live trees per hectare.
Nitrogen availability in forest floors of three tree species on the same site: the role of litter quality
Authors: Thomas K D , Prescott C E
Published: April 2011

Forest floor samples from a 25-year-old plantation of three tree species (Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), and paper birch (Betula papyrifera Marsh.)) growing on the same site were incubated (aerobically) in the laboratory for 29 days. Rates of N mineralization in the forest floors of Douglas-fir (165.1 µg/g) was significantly greater than either birch (72.9 µg/g) or lodgepole pine (51.2 µg/g). Douglas-fir forest floors also had the highest N concentration, lowest C/N ratio, and highest NH4-N concentrations, followed by paper birch and lodgepole pine. Douglas-fir forest floors also mineralized more N per unit of either N or C than the other species. There were no differences in rates of CO2-C mineralization in forest floors among the three species. Nitrogen mineralization rates were positively correlated with the N concentration of the forest floor (r2 = 0.81) and also with the C/N and NH4-N concentration of the forest floor. Nitrogen concentration, C/N, and lignin/N of foliar litter were poor predictors of N mineralization rates resulting from Douglas-fir litter having the lowest N concentrations in litter but the highest rates of net N mineralization in the forest floor. Nitrogen mineralization in the forest floor was negatively correlated (r2 = 0.67) with the lignin concentration in foliar litter. Douglas-fir litter had low lignin concentrations, which may allow more of the mineralized N to remain in inorganic forms rather than being bound in humus. Our results suggest that a component of Douglas-fir might improve N availability in coniferous forest floors.
Evaluation of somatic embryogenesis for clonal propagation of western white pine
Authors: Percy R E , Klimaszewska K , Cyr D R
Published: April 2011

A multiyear program was undertaken to develop a somatic embryogenesis system for clonal propagation of western white pine (Pinus monticola Dougl.). Developing seeds were used to initiate embryogenic lines from families used in blister-rust (Cronartium ribicola J.C. Fisch.) resistance breeding programs in British Columbia. The most responsive seeds contained zygotic embryos ranging in development from late cleavage polyembryony to the early dominance stage. Overall, 14 of 15 open-pollinated families produced embryogenic lines. The best results (0.8-6.7% initiation) were obtained using modified Litvay medium with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzyladenine (BA) at 2.25 µM. Proliferation of embryogenic tissue was enhanced by culturing tissue as a thin layer on filter paper supports. Approximately 300 lines representing 18 open- and control-pollinated families were cryopreserved. The highest number of mature somatic embryos was obtained on maturation medium containing 120 µM abscisic acid, 180 mM sucrose, and 1.0% gellan gum. Of 61 lines tested on this medium, 77% produced mature somatic embryos. In vitro germination and early growth occurred at a high frequency (90-95%), and plants from 45 genotypes were subsequently transferred to a greenhouse.
Econometric analysis of the causes of forest land use changes in Hainan, China
Authors: Zhang Yaoqi , Uusivuori Jussi , Kuuluvainen Jari
Published: April 2011

This paper addresses the effects of economic, demographic, and institutional factors on land allocation between forestry and other uses. A panel data set from Hainan Island in China and a generalized least squares estimation method, allowing individual effects for counties, are applied. The results indicate that higher timber prices have led to an acceleration in rain forest exploitation, but encouraged investment in plantation forests. Population growth is the driving force behind the loss of natural forests, but it is positively related to plantation forests. Decollectivization seems to have promoted plantation forests, but has not saved the rain forest. A higher share of forestry land owned by state-owned enterprises also fosters afforestation on wasteland, but seems to lead to faster exploitation of natural forest, at least initially. The uncertainty that existed in the early period of economic reform quickened the pace of resource extraction and deterred investment.
Genetics in sustainable forestry: the challenges for forest genetics and tree breeding in the new millennium
Authors: Burley J
Published: April 2011

The life's work of Professor Gene Namkoong helped to lay the theoretical and quantitative foundations for modern forest genetics and tree breeding. It also emphasized the practical and ethical issues of the conservation of forest gene resources. As we enter a new millennium the challenges facing forest geneticists and tree breeders include recognition of changing demands on forests for a range of forest products of different quantities and qualities; development and wise application of the new molecular technologies for genetic manipulation and practical breeding; presentation of the values of genetics to policy-makers and to the concerned public; capture of resources for research and development as forestry moves from the public sector to private institutions; and preparation for a future that is uncertain politically, economically, socially, and environmentally.
Clear-cutting and regeneration practices in Quebec boreal balsam fir forest: effects on snowshoe hare
Authors: Bellefeuille Sonia de , Bélanger Louis , Huot Jean , Cimon Agathe
Published: April 2011

We compared utilization by the snowshoe hare (Lepus americanus Erxleben) of recent clearcuts subjected to three regeneration scenarios commonly used in boreal forest: natural regeneration, plantation with herbicide release (glyphosate), and plantation with manual release (brushsaw). Refuges for snowshoe hare, on a landscape dominated by clearcuts, were also investigated. Colonization of regenerating sites by the hare comes late in the humid boreal forest because clear-cut stands take more than 10 years to reach the sapling stage. Our sites were in the seedling stage 79 years after cutting, and hares avoided them year round because of an inadequate protective cover. Therefore, regeneration treatments did not affect habitat use by the hare on a short-term basis. During the seedling stage, the snowshoe hare were found in the remaining forest which occupied at least 25% of the area of each home range. The preservation of residual forests is thus essential to maintain local populations on an area dominated by commercial clearcuts.
Lack of relationship between forest edge proximity and nest predator activity in an eastern Canadian boreal forest
Authors: Ibarzabal Jacques , Desrochers André
Published: April 2011

Nest predation risk often increases near forest edges in agricultural landscapes, but this pattern has rarely been found in forested landscapes. Whether this lack of relationship is general remains unclear, especially because no assessment of statistical power has been published. To (1) assess whether and how far nest predation risk is associated with forest edges and (2) avoid confounding effects of the surrounding landscape, we measured nest predator activity by placing baits at five distances (0, 30, 60, 90, and 120 m) from sharp, rectilinear forest edges that run along extensive tracts of forest. No association was found between distance to forest edges and bait discovery rates (P = 0.7). The lack of edge effect was unlikely to be caused by a lack of statistical power (1 - β > 0.8). However, bait discovery rates were significantly heterogeneous throughout the study area, and ground baits were taken at a greater rate than arboreal baits. Mice, voles, and red squirrels (Tamiasciurus hudsonicus (Erxleben)), all nest predators, were the main users of bait. Red squirrel occurrence, as estimated by playbacks, was higher in black spruce (Picea mariana (Mill.) BSP) than in balsam fir (Abies balsamea (L.) Mill.) stands but was not associated with a high bait predation rate. Our results strengthen support to the hypothesis that nests near open areas in managed boreal forests are not more at risk than forest-interior nests.
Productivity, resource use, and competitive interactions of Fraxinus uhdei in Hawaii uplands
Authors: Ares Adrián , Fownes James H
Published: April 2011

We examined stand growth, canopy development, and resource use of Fraxinus uhdei (Wenzig) Lingelsh, a nonindigenous tree grown in Hawaii, and its interactions with the native, N-fixing tree Acacia koa Gray. Along a gradient of decreasing rainfall with elevation, on Histosols, F. uhdei had decreased stand basal area, productivity, and canopy development. At high-elevation sites, productivity of F. uhdei was limited by N, and F. uhdei benefitted from association with A. koa, as (i) foliar N content of F. uhdei was positively related to aboveground net primary productivity (ANPP), (ii) leaf area index, biomass increment, and ANPP of F. uhdei increased in a single-species stand after N additions, but there was no response by either F. uhdei or A. koa in a mixed stand, and (iii) productivity of F. uhdei in mixed stands with A. koa at high-elevation sites was greater than in single-species stands, and F. uhdei foliage was enriched with N in proportion to the fraction of stand basal area in A. koa. Seemingly, growth of F. uhdei on Histosols was also limited by water availability, as an index of carbon isotope composition of leaves (δ13C), and, therefore, intrinsic water-use efficiency (WUE) increased with elevation. Biomass production of F. uhdei stands per unit leaf area and per unit intercepted radiation (ε) decreased with increasing elevation on Histosols. Decreased nitrogen-use efficiency and ε of F. uhdei on Histosols were both traded off against increased WUE.
Scots pine needle longevity and gradation of needle shedding along pollution gradients
Authors: Lamppu Jukka , Huttunen Satu
Published: April 2011

Scots pine (Pinus sylvestris L.) needle longevity and gradation of needle shedding (the time span with 9010% needle survival) in the middle and northern boreal vegetation zones were studied. The duration of the first half of gradual shedding (the time span with 9050% needle survival) was of special interest, because it represents the number of youngest cohorts that have lost needle biomass. Branches of adult trees along transects with an air pollution gradient were sampled. Mean longevity (the sum of survival proportions) decreased 1540% as pollution sources were approached. To rank or compare the values of a single needle age parameter, we prefer to use mean longevity. It gives an estimate of the whole needle biomass, and it was the parameter with the least variation. The first half of gradual shedding proved to be a valid indicator of changes in needle age structure. The most marked variation in needle age structure was seen in slightly polluted areas, which continued to pose a risk of acute pollution injuries. This study confirmed the feasibility of the needle age structure of branch samples as an objective and reliable vitality indicator for Scots pine.
Genetic structure of growth and phenological traits inSalix viminalis
Authors: Rönnberg-Wästljung Ann Christin
Published: April 2011

The genetic structure of Salix viminalis L. for different growth traits and bud flush has been studied. The aim was also to study differences in the genetic structure due to geographic origin and type of trait. Two incomplete factorial crossings with parental clones originating from Poland and Sweden were used. Growth traits showed a high amount of dominance genetic variance independent of parental origin. It is suggested that inbreeding depression found in S. viminalis could be a biological cause of the high levels of dominance as an alternative to overestimation due to epistasis. There were significant differences in amount of dominance genetic variance between the two origins for three of the nine growth traits. The higher number of characters influenced by dominance in the pedigree with Swedish origin can possibly be explained by linkage disequilibrium, since S. viminalis in Sweden has been introduced from Germany and Poland, and no sexual propagation of the species in Sweden has been reported. Bud flush showed high additive genetic variance in contrast to the growth traits. In the breeding for biomass production of S. viminalis, the high amount of dominance has to be taken into consideration.
DNA analysis of clonal structure of an old growth, isolated forest of Cryptomeria japonica in a snowy region
Authors: Moriguchi Yoshinari , Matsumoto Asako , Saito Maki , Tsumura Yoshihiko , Taira Hideaki
Published: April 2011

The regeneration system and clonal structure of Cryptomeria japonica D. Don were investigated in an old growth forest at an altitude of 1420 m, by examining root connections and DNA analysis. The C. japonica at this site was found to regenerate mostly by layering, and we found no clear evidence of regeneration through seedlings. Determining the clonal structure of this stand is much simpler by DNA analysis than by tracing root interconnections. The results of the DNA analysis suggest that all the C. japonica individuals present have close kinship. The study also supported earlier suggestions that the stand is becoming increasingly dominated by a few C. japonica clones with high levels of cold tolerance and good rooting ability. The formation of this type of stand appears to be strongly related to environmental factors such as the mean temperature and snow depth in winter.
Controls on conifer regeneration in managed riparian forests: effects of seed source, substrate, and vegetation
Authors: Beach Eric W , Halpern Charles B
Published: April 2011

Red alder (Alnus rubra Bong.) commonly dominates the overstory in managed riparian forests of the Pacific Northwest. Although it is assumed that competition with a dense shrub layer inhibits succession from hardwoods to shade-tolerant conifers within these forests, this assumption has not been explicitly tested. We hypothesized that seed availability rather than competitive interactions largely shape patterns of conifer regeneration in managed riparian forests. At nine locations in western Washington, we established paired transects in riparian sites adjacent to abundant versus few or no sources of seed to examine the importance for conifer regeneration of dispersal limitation, rooting substrate, and vegetation cover. Frequency and density of regeneration were significantly greater in transects within 100 m of remnant forest patches than in paired sites at greater distances (mean frequencies of 59 vs. 18% and densities of 0.23 vs. 0.16 trees/m2, respectively). Where seed sources were present, regeneration was positively associated with coarse woody debris and negatively associated with fine litter. Regeneration was most abundant in plots with <10% herb or shrub cover; however, for most species, recruitment occurred across the full range of understory plant cover. We detected no relationship between regeneration density and overstory conifer or hardwood cover. Our results suggest that, in managed forests, conifer regeneration is largely limited by seed availability and only secondarily by competitive interactions or substrate conditions. In managed landscapes, conventional strategies of vegetation control are not likely to be as effective in increasing conifer regeneration in riparian forests as managing for seed sources through green-tree retention.
Optimum breeding generation interval considering buildup of relatedness
Authors: Wei R -P , Lindgren D
Published: April 2011

Models taking genetic gain, relatedness, delay at generation turnover, and breeding population size into account have been developed to optimize selection age and generation interval. Relatedness (expressed as group coancestry) and average breeding value for the breeding population are merged into a joint index ("group merit"). The negative impact of group coancestry (like potential inbreeding depression) is expressed in a scale compatible with breeding value. Group merit measures the desirable characteristic of a breeding population. Annual increase of group merit is the criterion for comparing alternatives. Optimum generation interval is when annual group merit increase is highest. Generally the optimum selection age becomes higher when increase in relatedness is considered. We quantify the influence of relatedness penalty, early-mature genetic correlation, breeding population size, and delay at generation turnover on optimum selection age. A reasonable large population counteracts the increase of relatedness and, thus, favors early selection. Early selection can have a negative impact if a small early selection gain does not compensate for the buildup of relatedness at generation turnover. Conditions for this to occur are quantified. Early selection requires sufficient high juvenile-mature correlation to have a positive effect; this requirement can be reduced by using a large breeding population. The methods developed were applied to a number of situations relevant to forest tree improvement.
Gaps in a gappy forest: plant resources, longleaf pine regeneration, and understory response to tree removal in longleaf pine savannas
Authors: McGuire John P , Mitchell Robert J , Moser E Barry , Pecot Stephen D , Gjerstad Dean H , Hedman Craig W
Published: April 2011

Resource availability and planted longleaf pine (Pinus palustris Mill.) seedling and understory vegetation response within and among three sizes of experimentally created canopy gaps (0.11, 0.41, 1.63 ha) in a mature longleaf pine savanna were investigated for 2 years. Longleaf pine seedlings and understory vegetation showed increased growth in gaps created by tree removal. Longleaf pine seedling growth within gaps was maximized approximately 18 m from the uncut savanna. Increased longleaf pine seedling survival under the uncut savanna canopy observed after the first year suggests that the overstory may facilitate establishment of longleaf pine seedlings rather than reduce survival through competition. Despite the relative openness of the uncut longleaf pine forest, light quantity was increased by tree removal. Light was also the resource most strongly correlated with seedling and understory vegetation growth. Although net N mineralization was correlated to seedling response, the amount of variation explained was low relative to light. Belowground (root) gaps were not strong, in part because of non-pine understory roots increasing in biomass following tree removal. These results suggest that regeneration of longleaf pine may be maximized within gap sizes as small as approximately 0.10 ha, due largely to increases in light availability.
Infection of advance regeneration of Norway spruce by Heterobasidion parviporum
Authors: Piri Tuula , Korhonen Kari
Published: April 2011

The incidence of Heterobasidion root rot in the advance regeneration of Norway spruce (Picea abies (L.) Karst.) was studied in nine stands at four different localities in southern Finland. The mean age of the unthinned advance regeneration on the 17 sample plots ranged from 14 to 44 years. On infested plots, the proportion of Norway spruce infected by Heterobasidion varied from 22.2 to 75.0% (mean 52.5%) in the overstory and from 1.8 to 68.2% (mean 21.1%) in the advance regeneration. The corresponding values on healthy-looking control plots were 06.7% (mean 5.9%) and 1.33.9% (mean 2.4%), respectively. Of the 138 Heterobasidion genets identified, 98.5% belonged to Heterobasidion parviporum Niemelä & Korhonen and 1.5% to Heterobasidion annosum (Fr.) Bref. s.s. The incidence of Heterobasidion root rot in advance regeneration was positively correlated with the mean size and age of the advance regeneration and the proportion of infected trees in the overstory and negatively correlated with the regeneration density. Vegetative spread through root contacts from overstory trees to the surrounding regeneration accounted for at least 53% of the Heterobasidion infections in the advance regeneration. The origin of the rest of the infections in advance regeneration remained unclear, but at least part of them may have started from spore infection on injured or dead roots. Our results suggest that, on sites infected by H. parviporum, advance growth of Norway spruce should not be used for regeneration even though the spruces look healthy and show no external signs of infection.
Humus buildup in boreal forests: effects of litter fall and its N concentration
Authors: Berg Björn , McClaugherty Charles , Santo Amalia Virzo De , Johnson Dale
Published: April 2011

This synthesis paper presents a model for estimating the buildup of soil organic matter in boreal deciduous and coniferous forests. A basic model was developed using data from a well-studied Scots pine (Pinus sylvestris L.) forest (SWECON site) and based on limit values for litter decomposition and amounts of litter fall. A local validation gave a calculated humus accumulation that differed by 8% from the amount measured in the stand. This model was further validated using data for humus accumulated for 2984, 2081, and 1106 years, predicting an accumulation close to the measured amount, and for needle litter the missing fractions were 16, 17, and 6%, respectively, for the three groups. The limit value for litter decomposition is negatively related to the litter's initial N concentration; thus, N-rich litter should have a larger resistant fraction left than N poor. This relationship was validated using nine paired stands of monocultures: eight pairs of Scots pine and Norway spruce (Picea abies (L.) Karst.) and one pair of red alder (Alnus rubra Bong.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). The measured amount of SOM was related to foliar litter fall and its N concentration. In all cases the more N-rich litter gave in all cases the more N-rich Norway spruce litter gave a significantly higher accumulation of humus for Norway spruce in spite of a higher litter fall for Scots pine. Also, red alder gave more SOM than Douglas-fir and in an expected relation to the litter N concentration. A consequence of this would be that C sinks of different efficiencies or capacities would tend to accumulate SOM at different rates.
Introduction and evaluation of possible indices of stand structural diversity
Authors: Staudhammer Christina Lynn , LeMay Valerie Marie
Published: April 2011

Stand structural diversity is useful in forecasting growth and can be indicative of overall biodiversity. Many variables that indicate structural diversity can be measured. However, species, diameter, and height are commonly measured and indicate changes in vertical and horizontal stand structure. Indices based on the distribution of basal area per hectare by diameter, height, and species were derived and evaluated by applying them to simulated and actual data sets with a wide variety of stand structures. Extending the Shannon index of diversity to proportions by species, diameter, and height resulted in reasonable results with more diverse structures having higher values. However, diameter and height ranges must be divided into classes to use these indices. A new index based on the variances of the target stand, relative to the variance of a uniformly distribution stand, showed similar diversity measures to that of the Shannon index, without the need for dividing the diameter and height data into classes. Examination of these indices for use in growth and yield modelling of complex stands is needed.
Mélange de clones en taillis à courtes rotations de peuplier : influence sur la productivité et l'homogénéité des produits récoltés
Authors: Berthelot Alain
Published: April 2011

Two stands of short-rotation coppice of hybrid poplar were studied from age 3 to harvest (age 7 or 9). The performance of three clones planted at a density of 3000 stems/ha either in mixed- or mono-clonal stands was determined in each stand. Mean diameter and total biomass were not significantly different among the treatments (mixed- or mono-clonal stands). On the other hand, in mixed-clonal plots, biomass distribution was not equally distributed among clones. Diameter distribution was bimodal (two clones) or even trimodal (three clones). At one site (Tourtenay), mortality due to competition affected mostly the suppressed clone ('Boelare'). Mortality is significantly higher for this clone at age 7. With such closed spacings, competition occurs soon and social position is rapidly irreversible.
Factors contributing to the superior growth and N nutrition of 11-year-old lodgepole pine compared with Sitka spruce on a N-poor cedar-hemlock cutover
Authors: Bothwell Karen S , Prescott Cindy E , Jones Melanie D
Published: April 2011

We tested several hypotheses to explain the superior growth and nitrogen (N) status of lodgepole pine (Pinus contorta Dougl. ex Laws. var. contorta) compared with Sitka spruce (Picea sitchensis (Bong.) Carrière) on a N-poor site by comparing N distribution, N retranslocation, rooting distribution, and mycorrhizal fungi in plots of 11-year-old trees on a cedarhemlock cutover. Aboveground N content was nine times greater in pine than in spruce of the same age, and thus, we conclude that pine acquired more N during the 11 years than spruce. Greater N acquisition by pine was not related to rooting depth, as both species rooted primarily in the residual forest floor. There were differences in mycorrhizal fungal associates: a high proportion of pine roots were infected with Suillus-like fungi. Pine produced more aboveground biomass per unit N (388 compared with 292 g·g1 in spruce) and distributed more N to young foliage. Nitrogen retranslocation efficiency (based on foliar N contents in July and October) was higher in pine (5052%) than in spruce (2436%). These characteristics all appear to contribute to pine's abilities to both acquire more N and use it more efficiently and, thus, outperform spruce on this N-poor site.
Random amplified polymorphic DNA variability among geographic isolates of western gall rust fungus in Canada
Authors: Li Changxi , Yeh Francis C , Hiratsuka Yasu
Published: April 2011

Geographic variability among western gall rust (WGR) fungus (Endocronartium harknessii (J.P. Moore) Y. Hiratsuka) was studied by random amplified polymorphic DNA (RAPD). Samples were taken from lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) host at four locations in British Columbia and Alberta and from jack pine (Pinus banksiana Lamb.) host at nine locations in Alberta, Saskatchewan, Manitoba, and Ontario. Of 90 random oligonucleotide primers screened, 9 were chosen for analysis. These nine primers consistently amplified 41 sharp and reproducible RAPDs (fragments) of the WGR fungal isolates over several independent runs. Eighteen of the 41 RAPDs were polymorphic (showing the presence of both marker and null phenotypes), of which 15 could discriminate WGR isolates of lodgepole pine hosts from jack pine ones. Of these 15 RAPDs, five were unique to isolates of lodgepole and five to jack pine. The remaining five RAPDs were significantly heterogeneous in the RAPD frequency between WGR isolates of the two host origins. The RAPD pattern of WGR isolates from lodgepole pine was uniform. However, isolates from jack pine differed significantly in the frequency of four RAPDs among locations, with an east-west trend of decreasing similarity in RAPD. Analysis of molecular variance apportioned 76.3, 14.4, and 9.3% of the total RAPD variability to differences among hosts, to differences among locations within hosts, and to differences within locations, respectively. The large differentiation between WGR fungal isolates sampled in lodgepole pine and jack pine hosts might suggest that selective pressure for host specificity in sampled populations was strong.
A 5000-year record of disturbance and vegetation change in riparian forests of the Queets River, Washington, U.S.A.
Authors: Greenwald D Noah , Brubaker Linda B
Published: April 2011

We used fossil pollen, charcoal, and sediment stratigraphy in three small hollows to investigate disturbance events and changes in the composition of riparian forests on a small section of the Queets River floodplain, Olympic Peninsula, Washington. The records ranged in age from approximately 500 years at two sites 300 and 550 m from the river, to 5000 years at a site 800 m from the river. Approximately 400600 years BP, the two sites nearest the river were either inundated by a very large flood or covered by the active channel, which would have occupied a substantially different position than its present course. Following inundation or channel movement, the pollen record suggests that Alnus rubra Bong., the primary mesic forest colonizer in the Pacific Northwest, increased and was then replaced by Picea sitchensis (Bong.) Carrière and Tsuga heterophylla (Raf.) Sarg. At the site farthest from the river, two fires occurred within the last ca. 4500 years. One of the fires was followed by a period of shrub dominance and succession to Tsuga heterophylla. The other fire did not cause a change in the pollen record. A recent unprecedented rise in Tsuga heterophylla pollen, which began ca. 1000 years BP, might be in response to cooling during the Little Ice Age. Overall, the small hollow records highlight the complex effect of floods, fire, and possibly climate change on riparian forests of the Queets River.
Effets de trois scénarios de régénération de la sapinière boréale sur les passereaux nicheurs, les petits mammifères et le lièvre d'Amérique
Authors: Bellefeuille Sonia de , Gagné Nancy , Bélanger Louis , Huot Jean , Cimon Agathe , Déry Stéphane , Jetté Jean-Pierre
Published: April 2011

We compared wildlife utilization of recent clearcuts subjected to three regeneration scenarios commonly used in boreal balsam fir (Abies balsamea (L.) Mill.) forests: natural regeneration, plantation of black spruce (Picea mariana (Mill.) BSP) followed by herbicide release (glyphosate), and plantation of black spruce followed by manual release (brushsaw). The wildlife species studied were songbirds, small mammals and the snowshoe hare (Lepus americanus Erxleben). Surveys were conducted during the 2 years preceding and the 5 years following conifer release. The abundance of songbirds decreased the second and third years after both types of release, and the abundance of the red-backed vole (Clethrionomys gapperi Vigors) was reduced for 2 years following herbicide release. Snowshoe hares rarely used the stands during the 8 to 10 years that followed logging, so conifer release did not affect them. In this study, the short- and mid-term effects of the regeneration scenarios on wildlife may have been mitigated by the poor quality of clearcuts as wildlife habitats at the time of release and by the fact that plantations, like naturally regenerated sites, had a heterogeneous vegetation and a well-developed herb and shrub cover. In the humid balsam fir forest, where vegetation growth is slow and snow cover deep, the size and distribution of clearcuts would have greater effects on wildlife in the short and mid term than the regeneration scenario used for forest renewal. A landscape management approach inspired by natural disturbance dynamics is proposed as a mitigation measure.
Forest inventory of small areas combining the calibration estimator and a spatial model
Authors: Lappi Juha
Published: April 2011

The use of satellite images is considered to compute improved weights for field plots when estimating totals of forest variables over a region by weighted sums of plot measurements. It is intuitively appealing, and necessary in growth projections for management planning, that the weight of each plot can be interpreted as the total area of similar forest in the region. This way we can get a sound description for the whole region so that the relations and distributions of all predicted forest variables resemble the true population. Area interpretation is possible if the weights are positive and the same for all target variables. A calibration estimator provides such weights. If we need estimates for small subregions (counties in this study), we should utilize plots outside the current subregion. A spatial variogram model is suggested for computing the variance of the proposed small-area calibration estimator. Kriging provides optimal weights under such model, but the area interpretation for weights would not be possible. Estimation of county results using data from the Finnish National Forest Inventory and Landsat TM satellite showed that (i) outside plots should be utilized from a constant area around the county, i.e., the inclusion range should decrease when the size of the county increases, (ii) the combined use of neighboring plots and satellite data may lead to a large reduction in the error variance for small counties. In its current form, the method does not produce predictions for individual pixels.
A 400-year history of fire and oak recruitment in an old-growth oak forest in western Maryland, U.S.A.
Authors: Shumway Durland L , Abrams Marc D , Ruffner Charles M
Published: April 2011

We document the fire history and associated ecological changes of an old-growth forest stand in western Maryland, U.S.A. The study area is located on the side slopes of a ridge system (Savage Mountain). Twenty basal cross sections were obtained from old trees cut in 1986, which provided evidence of 42 fires from 1615 to 1958. Nine fires were recorded in the sample trees in the 17th century, 13 in the 18th century, 12 in the 19th century, and eight in the early to mid-20th century. However, there were no major fire years after 1930. The Weibull modal fire interval was 7.6 years. Oaks recruited consistently from the early 1600s to the early 1900s, but there was increased Acer rubrum L. and Betula lenta L. recruitment with fire suppression after 1930. Species recruitment patterns and long-term fire history reported in this study offer important direct support for the hypothesis that periodic fire played an important role in the historical development and perpetuation of oak forests of the mid-Atlantic region before and after European settlement.
Changes in cortical and wood terpenes in Sitka spruce in response to wounding
Authors: Nault J R , Alfaro Rene I
Published: April 2011

Terpene levels were measured in bark and wood samples of Sitka spruce (Picea sitchensis (Bong.) Carrière) trees. The trees that had been selected as early or late flushing were subjected to artificial wounding to simulate attack by the white pine weevil, Pissodes strobi (Peck). Samples were taken at four times during the growing season: before wounding, shortly after wounding, and two times later in the season. Terpenes were extracted with hexane and quantified by capillary gas chromatography. There were no significant differences in total bark terpenes between early- and late-flushing trees or between control and wounded trees over all sampling times. There were no significant differences in total wood terpenes between early- and late-flushing trees or among sampling times, but a statistically significant difference was found between control and wounded trees. Eleven individual terpenes accounted for the majority of the terpenes in the extracts. Four bark terpenes showed significant differences with sampling time, two with flushing class, and none with treatment. Five wood terpenes showed significant differences with sampling time, two with flushing class, and nine with treatment. We concluded that flushing had only a minor effect on bark and wood terpene profiles and that wounding significantly increased terpene concentration in wood shortly after injury.
Spacetime modelling of lightning-caused ignitions in the Blue Mountains, Oregon
Authors: Díaz-Avalos Carlos , Peterson David L , Alvarado Ernesto , Ferguson Sue A , Besag Julian E
Published: April 2011

Generalized linear mixed models (GLMM) were used to study the effect of vegetation cover, elevation, slope, and precipitation on the probability of ignition in the Blue Mountains, Oregon, and to estimate the probability of ignition occurrence at different locations in space and in time. Data on starting location of lightning-caused ignitions in the Blue Mountains between April 1986 and September 1993 constituted the base for the analysis. The study area was divided into a pixeltime array. For each pixeltime location we associated a value of 1 if at least one ignition occurred and 0 otherwise. Covariate information for each pixel was obtained using a geographic information system. The GLMMs were fitted in a Bayesian framework. Higher ignition probabilities were associated with the following cover types: subalpine herbaceous, alpine tundra, lodgepole pine (Pinus contorta Dougl. ex Loud.), whitebark pine (Pinus albicaulis Engelm.), Engelmann spruce (Picea engelmannii Parry ex Engelm.), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and grand fir (Abies grandis (Dougl.) Lindl.). Within each vegetation type, higher ignition probabilities occurred at lower elevations. Additionally, ignition probabilities are lower in the northern and southern extremes of the Blue Mountains. The GLMM procedure used here is suitable for analysing ignition occurrence in other forested regions where probabilities of ignition are highly variable because of a spatially complex biophysical environment.
Estimation of Eucalyptus delegatensis wood properties by near infrared spectroscopy
Authors: Schimleck L R , Evans R , Ilic J
Published: April 2011

The use of calibrated near infrared (NIR) spectroscopy for the prediction of a range solid wood properties is described. The methods developed are applicable to large-scale nondestructive forest resource assessment and to tree breeding and silvicultural programs. A series of Eucalyptus delegatensis R.T. Baker (alpine ash) samples were characterized in terms of density, longitudinal modulus of elasticity (EL), microfibril angle (MFA), and modulus of rupture (MOR). NIR spectra were obtained from the radiallongitudinal face of each sample and used to generate calibrations for the measured physical properties. The relationships were good in all cases, with coefficients of determination ranging from 0.77 for MOR through 0.90 for EL to 0.93 for stick density. In view of the rapidly expanding range of applications for this technique, it is concluded that appropriately calibrated NIR spectroscopy could form the basis of a "universal" testing instrument capable of predicting a wide range of product properties from a single type of spectrum obtained from the product or from the raw material.