bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural differences between forests regenerating following spruce budworm defoliation and clear-cut harvesting: implications for marten
Authors: Payer David C , Harrison Daniel J
Published: April 2011

American marten (Martes americana Turton) avoid recent clearcuts when establishing territories but do not avoid similarly aged stands with a history of extensive tree mortality caused by the eastern spruce budworm (Choristoneura fumiferana Clem.). We quantified differences in overstory vegetation, understory vegetation, and coarse woody debris between stands that were clear-cut or defoliated by spruce budworms 10-20 years prior to our study. Our objectives were to identify habitat features with functional significance for marten that were lacking in managed stands and to propose goals for silvicultural practices that more closely resemble a natural disturbance (insect defoliation), thus improving habitat quality for marten. In contrast to regenerating clearcuts, defoliated stands had greater volumes of snags, downed logs, and root masses and included taller trees. Although live-tree basal area was similar between stand types, our results suggest that vertical structure provided by large snags can offset limited availability of live trees for marten, particularly where coarse woody debris and understory vegetation are plentiful. In stands under even-aged management, habitat quality for marten may be enhanced by retention of >18 m2/ha cull trees and snags. Uneven-aged silvicultural systems, which more closely mimic natural disturbance by defoliating insects, may have particular promise for maintaining marten habitat.
Three methods of deriving advanced dynamic site equations demonstrated on inland Douglas-fir site curves
Authors: Cieszewski C J
Published: April 2011

With two examples of five-parameter, fixed-base-age site index and height growth equations, I demonstrate three methods for deriving dynamic equations that are base-age invariant and use only three parameters. These are initial condition difference equations that compute appropriate heights at all base ages and provide compatible height and site index values from one common equation. Despite having fewer parameters, they can model a broader selection of curves than the original equations. The new equations are applicable for all situations in which the original equations could be applied. Methods demonstrated in this paper can enhance the development of all recursive and otherwise implicitly defined equations used for modeling of height, diameter, basal area, volume, number of trees per hectare, and investment yields.
Genetic diversity and mating system of post-fire and post-harvest black spruce: an investigation using codominant sequence-tagged-site (STS) markers
Authors: Perry Daniel J , Bousquet Jean
Published: April 2011

cDNA-based sequence-tagged-site (STS) markers were used to examine the genetic composition of three mature, layer-origin populations of black spruce (Picea mariana (Mill.) BSP), which were the result of logging operations in the first half of the 20th century, and compare them with four mature, seedling-origin populations that regenerated naturally following fire. The amount of STS-marker variation revealed in these populations was very similar to that previously observed in a rangewide panel of black spruce trees. There was little differentiation among populations, and no significant differences in heterozygosities, numbers of alleles, or fixation indices were evident between layer-origin and fire-origin stands. Likewise, when mating-system parameters were estimated in one population of each of these two types, no significant differences were found; outcrossing was essentially complete with no evidence of mating among relatives. The estimated correlation of paternity within progeny arrays was about 17 and 13% in the fire-origin and layer-origin stands, respectively, but again the observed difference was not statistically significant. At least at the current scale of sampling, silvicultural practices that result in stand replacement by layer-origin advance regeneration appear not to have had negative impact upon the genetic diversity or level of inbreeding in second-growth black spruce stands.
Overlaying compacted or uncompacted construction fill has no negative impact on white oak and sweetgum growth and physiology
Authors: Day Susan D , Seiler John R , Kreh Richard , Smith David W
Published: April 2011

Raising the soil grade, frequently required during building construction, is thought to damage trees and is of concern to foresters responsible for tree protection on such sites. We investigated the effects of applying fill over the roots of 22-year-old white oaks (Quercus alba L.) and 13-year-old sweetgums (Liquidambar styraciflua L.). Treatments included a control (no fill), fill (sandy loam C horizon soil spread 20 cm deep), and compacted fill (same as fill but compacted). Trees with fill had soil held away from trunks or not. After 3 years, there was no consistent treatment effect on growth, chlorophyll fluorescence, or soil respiration in either species. Fill disrupted normal soil moisture patterns. White oak plots with fills had lower soil water contents than controls. In sweetgum plots, soil underlying fill was typically drier than fill layers, whereas control plot soil moisture tended to increase with depth. Fills did not affect overall root density for either species. White oak grew roots well into fill soils, but sweetgum did not, although sweetgum root distribution shifted upwards under fills. Other factors associated with raising the grade, such as soil trafficking and root severance, may be responsible for much of the tree decline attributed to fill.
Estimating forest productivity in the eastern Siskiyou Mountains of southwestern Oregon using a satellite driven process model, 3-PGS
Authors: Coops N C , Waring R H
Published: April 2011

The 3-PGS (physiological principles for predicting growth using satellite data) model generates monthly estimates of transpiration, photosynthesis, and net primary production (NPP), the latter derived as a fixed proportion (0.47) of gross photosynthesis. To assess the reliability of a simplified process model (3-PGS) to predict the productive capacity of coniferous forest across diverse landscapes in southwestern Oregon, we first used a geographic information system to display and manipulate basic data. This involved the following steps: (i) extrapolate monthly mean weather data to reflect topographic variation; (ii) transform monthly temperature extremes to spatial resolution of 4 ha and estimate incoming solar radiation, subfreezing days per month, daytime vapor pressure deficits, and mean temperatures; (iii) convert statewide soil survey maps into topographically adjusted estimates of soil fertility and water storage capacity (θ); and (iv) acquire satellite-derived estimates of the faction of light intercepted by vegetation during midsummer. Model predictions of soil water availability during summer months compared well with those reported from published measurements of predawn water potentials at three contrasting sites and with measurements acquired at the end of seasonal drought at 18 sites (r2= 0.78 with mean monthly modeled drought index; r2= 0.57 with seasonal modeled drought index). Similarly, seasonal shifts in the relative importance of various climatic and edaphic variables closely matched those defined in previously published studies. Finally, model predictions of maximum annual aboveground growth were compared with those derived from forestry yield tables based on height-age relationships with a resulting r2of 0.76, and a standard error of 1.2 m3·ha-1·year-1(P < 0.01).
Bacterio-opsin gene overexpression fails to elevate fungal disease resistance in transgenic poplar (Populus)
Authors: Mohamed Rozi , Meilan Richard , Ostry Michael E , Michler Charles H , Strauss Steven H
Published: April 2011

Overexpression of the bacterio-opsin (bO) gene in tobacco had previously been shown to induce hypersensitive-response-like lesions, increase viral and bacterial disease resistance, and stimulate pathogenesis-related gene expression. To see if this gene enhanced resistance to fungal pathogens of poplar, we generated a total of 35 transgenic lines in two clones of Populus trichocarpa Torr. & A. Gray × Populus deltoides Bartr. ex Marsh. and one clone of P. trichocarpa × Populus nigra L. and challenged them with the fungal pathogens Melampsora occidentalis H. Jack (leaf rust), Venturia populina (Vuill.) Fabric. (leaf and shoot blight), Septoria musiva Peck, and Septoria populicola Peck (leaf spot and stem canker) in greenhouse, field, or laboratory inoculations. Northern analysis showed that the bO gene was expressed in the transgenic poplars; however, no increase in expression of phenylalanine ammonia-lyase (PAL1) or two wound-inducible poplar chitinase genes (WIN6 and WIN8) were observed, even in one line that showed very high bO expression, intensive lesion development, and retarded growth. Poplars required a high threshold of bO expression for lesion development, and susceptibility to all of the pathogens tested was unaffected by bO overexpression.
Leaf/sapwood area ratios in Scots pine show acclimation across Europe
Authors: Mencuccini Maurizio , Bonosi Lorenzo
Published: April 2011

We tested the hypothesis that leaf/sapwood area ratios (S) in Scots pine (Pinus sylvestris L.) differ across Europe. Data from published records were collected and critically reviewed, and five new sites were studied to increase the overall sample size available for analyses. For seven studies for which data were available, we also determined the magnitude of the errors resulting from the use of ratio and regression-type estimators during subsampling for leaf areas of individual trees. These subsampling errors were then compared with those resulting from least square regressions of leaf area against sapwood area, and the total error was determined. Finally, correlation analysis was used to test for significant relationships between S and site-specific and stand-specific variables. Subsampling for leaf area resulted in errors, the magnitude of which was site specific and depended on sampling sizes and protocols. In general, despite larger total errors resulting from accounting for subsampling, significant differences were found among S, both at breast height and at the base of the living crown, at least for the most extreme cases. Significant negative relationships were found between S and summer vapour pressure deficit and maximum summer temperature. Although preliminary, our results confirm previous suggestions about climatic effects on Scots pine leaf/sapwood area ratios by enlarging the analysis to a wider range of European sites and by including genetic variability across stands.
Analysis of temporal variation and species-site relationships of witness tree data in southeastern Pennsylvania
Authors: Black Bryan A , Abrams Marc D
Published: April 2011

Witness tree species  site relationships are described with respect to parent material, soil drainage, and soil surface texture in Lancaster County, southeastern Pennsylvania. Quercus velutina Lam. and Carya were positively associated with "limestone" parent materials and well-drained, loamy sites. Quercus velutina was strongly associated with "acid shale and sandstone" parent materials and well-drained, upland soils. Quercus alba L. was most abundant on parent material classes associated with stream valleys and coves while Qurecus prinus L. and Castanea dentata (Marsh.) Borkh. were positively associated with well-drained, rocky sites on "quartzite" parent materials. Procedures were then developed to test for significant changes in witness tree species frequencies over the 100-year period of metes and bounds surveys in Lancaster County. These tests revealed that Quercus coccinea L., Nyssa sylvatica Marsh., and early successional species were surveyed much later than Quercus rubra L., Q. alba, and Carya spp. Agricultural land clearing, cutting for firewood, selective logging, and the charcoal-iron industry all probably contributed these species changes. Overall, abundances of minor species appear to be much more sensitive to these early settlement land uses. Given the extent of metes and bounds surveys, these tests for temporal variations may be applied to witness tree data throughout the eastern United States.
Extracting a paleotemperature record from Picea engelmannii tree-line sites in the central Canadian Rockies
Authors: George Scott St , Luckman Brian H
Published: April 2011

A new network of 21 Picea engelmannii Parry ex Engelm. ring-width chronologies was developed from tree-line sites in the Canadian Rockies. These chronologies range in length from 297 to 648 years (mean 423 years) and have mean sensitivities between 0.16 and 0.20 (mean 0.18), first-order autocorrelations between 0.73 and 0.88 (mean 0.83), and subsample signal strengths >0.85 for 246-494 years (mean 324 years). Mean intersite correlations (A.D. 1700-1982) for chronologies with expressed population signals >0.85 are 0.46 and 0.63 for standard and residual chronologies, respectively. Standard ring-width chronologies are, in general, positively correlated with summer temperatures and negatively correlated with spring and previous summer temperatures. A regional June-September temperature reconstruction for the Banff-Jasper region (BJR; A.D. 1715-1982) was developed using multiple regression of three significant principal components from 14 standard ring-width chronologies. The first principal component contains 55% of the total chronology variance. The model reconstructs 38% of summer temperature variance during the calibration period (1888-1982). The BJR is the first regional temperature reconstruction for this area based on ring-width data from a network of sites. The reconstructed temperature patterns are broadly similar to other regional estimates of past temperatures. Above-average summer temperatures occurred in the mid-20th century and the late 1700s - early 1800s. Most of the 19th century was unusually cold, with the coldest conditions in the late 19th century. Detailed differences between BJR and previously developed reconstructions lie well within 2σ confidence limits and may reflect differences in tree species, modelling techniques, spatial coverage, and the seasonal temperature parameter reconstructed.
The potential for woody understory plants to provide refuge for ectomycorrhizal inoculum at an interior Douglas-fir forest after clear-cut logging
Authors: Hagerman Shannon M , Sakakibara Stacey M , Durall Daniel M
Published: April 2011

Clear-cut logging can decrease the amount of inoculum for some ectomycorrhizal fungi. Ectomycorrhizal plants that are not selected for harvest (refuge plants) may, therefore, be important for the maintenance of ectomycorrhizal fungal inoculum in clearcuts following logging. The purpose of this study was to identify refuge plants that could provide ectomycorrhizal fungal inoculum for outplanted seedlings. The ectomycorrhizal status of selected plants was assessed in 1.6-ha clearcuts and in adjacent forest. Over 3 years, 17 and 14 morphotypes were described for Pseudostuga menziesii (Mirb.) Franco (Douglas-fir) and Arctostaphylos uva-ursi (L.) Spreng, respectively. Ten morphotypes (six of these confirmed with restriction fragment length polymorphism patterns) were shared by both species. Anatomical and molecular analyses revealed that, for the morphotypes observed, ectomycorrhizal fungi formed ectomycorrhizal anatomy when associated with Douglas-fir and arbutoid anatomy with A. uva-ursi. Because advanced regeneration seedlings of Douglas-fir and A. uva-ursi are well distributed throughout this site, these two species have a high potential to provide ectomycorrhizal fungal inoculum for outplanted seedlings. There was no difference in mycorrhizal richness between A. uva-ursi plants sampled from the clearcut and forest in the latter 2 years of the study. Conversely, the richness of ectomycorrhizae associated with Douglas-fir sampled from the forest was significantly greater than for seedlings sampled from the clearcuts.
Genetic response to within-family selection using molecular markers in some radiata pine breeding schemes
Authors: Kumar Satish , Garrick D J
Published: April 2011

Marker-assisted selection (MAS) provides an opportunity to increase the efficiency of within-family selection in forest tree breeding. Within-family MAS involves selection decisions first made on conventional breeding values and quantitative trait loci (QTL) information used for within-family selection. In this study genetic response obtained by using MAS was compared with conventional methods for three options: "full-sib family forestry," "clonal forestry," and "forward selection for deployment." This comparison was undertaken using stochastic simulation for a locus that explained 10 or 20% of the genetic variance. In the full-sib family forestry scenario, markers were used to select genotypes (among juvenile individuals in a family) for vegetative propagation. Markers were used to preselect genotypes for clonal testing in clonal forestry option. In case of forward selection for deployment option, offspring that have favourable marker haplotype and a superior phenotype were selected from each family. The comparison between the MAS and the conventional strategy was evaluated in genetic terms based on comparison of the average genetic merit of the genotypes used for deployment in production plantations. The relative genetic gain (%) using MAS were found to be 48% and 23% higher compared with conventional strategy for full-sib family forestry and clonal forestry options, respectively. In case of forward selection for deployment option, MAS was generally found to be providing higher genetic gain only when the heritability is low.
Whole-tree biomass and carbon allocation of juvenile trees of loblolly pine (Pinustaeda): influence of genetics and fertilization
Authors: Retzlaff W A , Handest J A , O'Malley D M , McKeand S E , Topa M A
Published: April 2011

To assess the contribution of belowground biomass allocation towards total carbon (C) allocation of two provenances of loblolly pine (Pinus taeda L.), we examined the total biomass allocation of a fast- and slow-growing family from each provenance. Since planting on a xeric, infertile site in Scotland County, N.C., U.S.A., trees in this study have been subjected to one of two nutrient treatments: optimal nutrition or control (no fertilization). Total biomass of 24 (1 tree/family plot × 2 families × 2 provenances × 2 treatments × 3 blocks) 5-year-old (juvenile) trees was harvested in January 1998. Fertilization increased total root, total shoot, and total tree biomass in all families as compared with harvested trees in control plots. Fertilization also increased biomass of coarse-root, woody-root, taproot, stem, branch, and foliar components of families as compared with trees in control plots. Although there were treatment and family differences in standing-crop biomass of the total root, total shoot, total tree, and various individual root and shoot components, the percent biomass (whole-tree) allocation to these tissues remained similar across treatments. Total nonstructural carbohydrate (TNC) analysis indicated some treatment, family, and provenance differences in TNC concentrations and partitioning to starch and soluble sugars. At the time of harvest, TNC concentrations of belowground tissues were much higher than those of aboveground tissues, and enhanced partitioning towards starch in root tissues indicates an important C storage role for belowground tissues at this time. Indeed, more than 90% of the trees starch content was present in root tissue in January. Although constrained by a sample size of three harvested trees per family, this study suggests that biomass allocation on a whole-tree level was similar between fast- and slow-growing families of different provenances of juvenile loblolly pine and was not affected by fertilizer treatment.
A parametric model of the fire-size distribution
Authors: Cumming S G
Published: April 2011

This paper developes statistical models of the size distribution of lightning-caused wildfires in the boreal mixedwood forests of Alberta, Canada, for the intervals 1980–1998 and 1961–1998. Above any minimum threshold size [Formula: see text]3 ha, the logarithm of fire size is approximately exponentially distributed. However, computer simulations using the best-fit distribution would over predict the frequency of large fires, and thus the mean rate of disturbance. A truncated exponential distribution, which places an upper bound on fire size, is more suitable and, according to probability plots, provides an excellent fit to the data. I estimate the maximum fire size in the study area to be [Formula: see text] 650 000 ha. This estimate is insensitive to the choice of lower bound for fire sizes (between 3 and 1000 ha) and to the choice of sampling interval. Parametric modelling of fire sizes using covariates derived from forest inventory data shows that the expected size of a fire is positively related to the abundance of pine forest in the vicinity of the point of detection and negatively related to the abundance of recently logged or burnt areas. This implies that variation in forest structure and disturbance history impose marked spatial variability on the fire size distribution. Other covariates, such as periodic indices of fire weather, could readily be evaluated in this framework.
Root biomass of regenerating aspen (Populus tremuloides) stands of different densities in Alberta
Authors: DesRochers Annie , Lieffers Victor J
Published: April 2011

In north-central Alberta, 12 plots (9 m2) were hydraulically excavated in young trembling aspen (Populus tremuloides Michx.) stands (510 years old) of different sucker density to quantify the effects of sucker density on the parental root system, on the formation of new roots and on the growth of suckers. All roots were collected and divided into live and dead parental roots and new root categories. Size and age of parent roots at the time of suckering were determined. Total biomass ranged from 1 to 18 t/ha of live roots. Living root biomass was proportional to stand density and leaf area index (LAI). Low-density stands had a higher proportion of dead roots. Suckers in plots with more parental root biomass/sucker had greater height growth. Root/shoot ratios ranged from 0.46 to 3.52 but were not correlated with stand densities. Stands with larger basal area of suckers and greater mean parent root diameter produced more biomass of new roots. This research suggests that young sucker-origin aspen stands support a large underground biomass and that high sucker densities and LAI are required to prevent loss of parental root biomass.
Modalités de la déforestation dans le sud-ouest de l'État du Campeche, Mexique
Authors: Mas J F , Puig H
Published: April 2011

The analysis of satellite images shows an important reduction of forest cover in the Lagoon of Términos region in the State of Campeche (southeastern Mexico) over the last decades. Deforestation rates reached 2.2 and 5.3%, respectively, on a yearly basis during 19741986 and 19861991. The deforestation process was modelled using a geographic information system. The model allows to determine how elements such as roads or human settlements proximity, land tenure, shape of the forest patches, slope, soil type, and human population attributes have an impact on the deforestation process. Deforestation was more severe in opened, nonflooded areas, with fertile soil, near roads and human settlements. Human population attributes showed little influence on deforestation rates, probably because pasture lands encroachment was recognized as the main cause of forest clearing. However, the model does not highlight the root causes of this phenomena, such as government policy on settlement and subsidies for cattle ranching. Despite this limitation, it allows to generate deforestation risk assessment maps that correctly identify the forest areas most susceptible to deforestation.
Growth and nitrogen retranslocation of nutrient loaded Picea mariana seedlings planted on boreal mixedwood sites
Authors: Imo Moses , Timmer Victor R
Published: April 2011

Enhanced nutrient mobilization from old to current growth is a key mechanism that confers competitive ability to nutrient-loaded black spruce (Picea mariana (Mill.) BSP) seedlings planted on high-competition forest sites in northern Ontario. This study examines effects of nutrient loading and differing vegetation management (herbicide, fertilization, shading) on growth, partitioning, and net retranslocation of N between current and old shoots of newly planted black spruce seedlings on six contrasting boreal sites. Nutrient loading during nursery culture improved seedling growth and N uptake and retranslocation after transplanting. Herbicide application accelerated growth and N uptake only on the high-competition Alnus, hardwood, and mixedwood sites but had no effect on the less competitive feathermoss and Vaccinium sites. Weed removal on competitive sites reduced N retranslocation significantly. Field fertilization reduced N retranslocation in seedlings and promoting tree growth and N uptake on the less competitive feathermoss and Vaccinium sites. However, fertilization stimulated weeds on high-competition sites suppressing seedling biomass and N uptake. Factors that seem to affect net N retranslocation include the type and level of internal N reserves, biomass and N accumulation and partitioning, external N supply, and other stresses that limit plant growth such as competition.
Salmonberry and salal annual aerial stem production: the maintenance of shrub cover in forest stands
Authors: Tappeiner, II John C , Zasada John C , Huffman David W , Ganio Lisa M
Published: April 2011

Annual sprouting of aerial stems and ramets enables populations of salmonberry (Rubus spectabilis Pursh), salal (Gaultheria shallon Pursh), and probably other forest shrubs to maintain dense covers (>20 000 stems/ha). We studied annual stem production of salmonberry on cut (all stems cut within 15 cm of the ground) and uncut (stems were not treated) plots for 8 years and salal for 5 years in the understories of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), alder, and riparian stands, as well as clearcuts, which are all common stand types in western Oregon. Mean salmonberry stem production on uncut plots ranged from 4.7 stems·m2·year1 (95% CI 2.97.4) in alder stands and clearcuts to 1.6 stems·m2·year1 (95% CI 1.02.6) in conifer stands. Mean salal production was greater, ranging from 58 stems·m2·year1 (95% CI 25135) to 8.6 stems·m2·year1 (95% CI 3.720.1) on uncut plots in clearcuts and unthinned Douglas-fir stands, respectively. Annual production of both species was somewhat greater on cut plots. Most stems produced in early spring die by December, but enough are recruited to replace mortality of older stems. Stem density was maintained for 8 years for salmonberry and 5 years for salal on both cut and uncut plots. Based on length of rhizomes and bud density we estimate that only 15% of the buds in the rhizomes are needed to support this annual stem production. Although these species sprout vigorously after their aerial stems are killed, disturbance is not necessary for maintaining a dense cover. It appears that, once established, salal, salmonberry, and probably other clonal forest shrubs can maintain a dense cover that can interfere with establishment of trees and other shrubs in canopy gaps or other openings.
Forest soil characteristics in a chronosequence of harvested Douglas-fir forests
Authors: Griffiths Robert P , Swanson Alan K
Published: April 2011

This study was designed to measure the microbiological and chemical characteristics of forest soils in a chronosequence of harvested Douglas-fir (Pseusotsuga menziesii (Mirb.) Franco) stands in different climatic settings. Mineral soil samples were collected along transects running from old-growth (OG) forests into harvested stands of ages 5, 15, and 40 years (5YS, 15YS, and 40YS, respectively) in the H.J. Andrews Experimental Forest in the central Oregon Cascade Mountains. We took litter depth measurements and cores to test for the presence of mycorrhizal mats at each sampling location. Denitrification potential was significantly lower in OG than in 5YS, and litter depth, forest floor respiration rate, and concentration of ectomycorrhizal mats were significantly greater in OG than in 5YS. Values were intermediate in 15YS and similar to those measured in OG in 40YS. No significant stand-age differences occurred in soil organic matter, soil moisture, pH, mineralizable N, laboratory soil respiration rate, or extractable ammonium. Sample variability was generally lowest in OG forests and highest in 5YS, and no consistent autocorrelations were observed for any of the variables at lags of 5 m or greater. We found no second-level interactions between stand age and location in ANOVA analyses, suggesting that, within the limits of this study, climate did not influence soil response to disturbance and subsequent recovery; however, several soil properties were affected by site location and, therefore, climate.
Which rotation length is favourable to carbon sequestration?
Authors: Liski Jari , Pussinen Ari , Pingoud Kim , Mäkipää Raisa , Karjalainen Timo
Published: April 2011

Regulating the rotation length of tree stands is an effective way to manage the carbon budget of forests. We analyzed, using models, how a 30-year change in rotation length from the recommended 90 years would change the carbon and energy budgets of typical wood-production and wood-use chains in Finland. Shortening the rotation length towards the culmination age of mean annual increment decreased the carbon stock of trees but increased the carbon stock of soil, because the production of litter and harvest residues increased. Changes in the carbon stock of wood products varied with tree species depending on volumes and timber sorts harvested, manufacturing processes and products manufactured. The Scots pine (Pinus sylvestris L.) chain stored the largest total amount of carbon when applying the longest rotation length and the Norway spruce (Picea abies (L.) Karst.) chain, when applying the shortest rotation length. Fossil carbon emissions and energy use in harvesting and manufacture increased when the rotation length was shortened and pulpwood harvests increased, especially in the spruce chain. We concluded that longer rotation length at the sites of both tree species would be favourable to carbon sequestration. The costs of this would be decreased timber harvests and decreased revenues of landowners. Our results demonstrate the importance of accounting for the whole wood-production and wood-use chain, including fossil carbon emissions, when analysing the effects of rotation length on forest carbon sequestration.
The influence of stand structure on ecophysiological leaf characteristics of Pinus ponderosa in western Montana
Authors: Nagel Linda M , O'Hara Kevin L
Published: April 2011

The effects of vertical arrangement of foliage in even-aged and multiaged stand structures of ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) on overall stand growth, light interception, and physiological leaf properties were tested on five plot pairs in western Montana. The primary structural difference between stand structures involves greater canopy depth and stratification of foliage in the multiaged stands. Both area- and mass-based maximum photosynthetic rates (Aarea and Amass) were relatively constant with canopy depth in both stand structures. Area- and mass-based leaf nitrogen (Narea and Nmass) decreased with increasing canopy depth in the even-aged stand structures but not in the multiaged. Specific leaf area (SLA) tended to increase with increasing canopy depth, although this relationship was only significant in the multiaged stand structures. The typical linear relationship observed for many species between photosynthetic rate and leaf nitrogen was not present in either stand structure; however, Narea was highly correlated to SLA in both even-aged and multiaged stand structures (R2 = 0.66 and R2 = 0.52, respectively). There were no differences in the light extinction coefficient (k), basal area growth or efficiency, or stand-level leaf area index between even-aged and multiaged plot pairs. Relative constancy in leaf physiology combined with similarities in site occupancy and growth rates help explain how different stand structures of ponderosa pine maintain similar rates of woody biomass productivity.
Neighborhood competition and crown asymmetry inAcer saccharum
Authors: Brisson Jacques
Published: April 2011

A tree neighboring a new gap must show a certain degree of morphological plasticity in its lateral growth to take advantage of the available space, expanding branches preferentially on the side of the gap. I evaluated the morphological plasticity of sugar maple (Acer saccharum Marsh.) by measuring crown asymmetry with respect to four different neighborhood contexts. Isolated trees have the most symmetrical crown, while all trees at the edge of a field have the largest part of their crown growing away from the forest. Asymmetry of trees at the edge of a forest and a recently constructed right-of-way is intermediate. The crown of forest trees is more developed away from the main competitive pressure of neighboring trees, with a disproportionate influence of the strongest neighbor. This crown development minimizes the negative effects of the interference with neighbors when competition is asymmetrical around a tree. The simplest mechanism allowing morphological plasticity and the resulting crown asymmetry involves a certain degree of autonomy of individual branches. Yet, branch autonomy is less likely for deciduous trees with determinate, single-flush growth patterns such as sugar maple. Some aspects of plasticity in sugar maple need to be investigated, especially with regard to a process where trees could compensate for the negative effects of close neighbors.
Douglas-fir soil C and N properties a decade after termination of urea fertilization
Authors: Homann Peter S , Caldwell Bruce A , Chappell H N , Sollins Phillip , Swanston Chris W
Published: April 2011

Chemical and microbial soil properties were assessed in paired unfertilized and urea fertilized (>89 g N·m2) plots in 13 second-growth Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands distributed throughout western Washington and Oregon. A decade following the termination of fertilization, fertilized plots averaged 28% higher total N in the O layer than unfertilized plots, 24% higher total N in surface (05 cm) mineral soil, and up to four times the amount of extractable ammonium and nitrate. Decreased pH (0.2 pH units) caused by fertilization may have been due to nitrification or enhanced cation uptake. In some soil layers, fertilization decreased cellulase activity and soil respiration but increased wood decomposition. There was no effect of fertilization on concentrations of light and heavy fractions, labile carbohydrates, and phosphatase and xylanase activities. No increase in soil organic C was detected, although variability precluded observing an increase of less than ~15%. Lack of a regionwide fertilization influence on soil organic C contrasts with several site-specific forest and agricultural studies that have shown C increases resulting from fertilization. Overall, the results indicate a substantial residual influence on soil N a decade after urea fertilization but much more limited influence on soil C processes and pools.
Modelling analysis of potential carbon sequestration in selected forest types
Authors: Nabuurs G.J. , Mohren G.M.J.
Published: April 2011

Ten selected forest types were examined (1) to assess the carbon sequestering potential of those forest types that are most likely to be successful in sequestering atmospheric carbon, (2) to show the relevance of varying carbon sequestering criteria, and (3) to present a method as a possible standard for carbon sequestering assessments. The carbon sequestering potential of the forest, forest soils, and forest products was quantified with the dynamic model CO2FIX. Two main criteria for evaluation of the carbon sequestering capacity were used: (1) the long-term average stock of carbon in the forest biomass and wood products and (2) the average net annual carbon storage flux during the first rotation. It was found that selectively logged evergreen rain forests may contain the largest long-term average stock of carbon in the biomass and products, with 207 Mg C•ha−1. The highest net annual carbon fixation in the first rotation was achieved with Pinusradiata D. Don in Brazil, with a storage rate of 5.3 Mg C•ha−1•year−1 on fertile sites. These values can be regarded as maximum boundaries for carbon sequestration. Evaluation of carbon sequestration in forests should always be carried out with a set of varying carbon sequestering criteria. Such an evaluation should also take into account socioeconomic and ecological criteria. It remains a political issue which criterion prevails over the other. A study to improve the model by linking it to forest type area tables is in preparation. It will then be possible to present projections of carbon sequestration for a region or country.
Detecting landscape changes in the interior of British Columbia from 1975 to 1992 using satellite imagery
Authors: Sachs Donald L , Sollins Phillip , Cohen Warren B
Published: April 2011

To consider the regional scale effects of forest management requires complete and consistent data over large areas. We used Landsat Thematic Mapper and Multispectral Scanner (TM and MSS) imagery to map forest cover and detect major disturbances between 1975 and 1992 for a 4.2 x 106 ha area of interior British Columbia. Forested pixels were mapped into closed conifer, semiopen conifer, deciduous, and mixed forest classes, with further subdivision of the closed conifer type into three age-classes. The image-based estimate of harvested area was similar to an independent estimate from forest inventory data. Changes in landscape pattern from 1975 to 1992 were examined by calculating indices that describe overall landscape pattern and that of conifer and harvested patches in each biogeoclimatic zone. Harvesting affected 8.4% of the forest area outside provincial parks during the 17-year period. Harvested areas were consistently much smaller than conifer patches in all biogeoclimatic zones and had a lower percentage of interior area and perimeter/area ratio. Conifer patch-shape complexity varied between zones; harvested patches had simpler shapes and were similar in all zones. Results indicate that this landscape is only in the early stages of fragmentation, but a similar harvest pattern has been imposed on differing ecological zones.
Impact à court terme d'une coupe avec protection de la régénération sur la gélinotte huppée (Bonasaumbellus) en forêt boréale
Authors: Dussault Christian , Courtois Réhaume , Ferron Jean
Published: April 2011

We studied the short-term impact of cutting with the protection of regeneration (CPR) on ruffed grouse (Bonasa umbellus) and its habitat. Drumming males were surveyed in the boreal forest of western Quebec between 1990 and 1994 in 5 control stands and 10 stands that were cut in 1992. Cutting caused a 50% decline in total density and basal area of trees. In harvested stands, shrubs were less abundant than in control stands. Lateral cover between 1 and 2 m and canopy closure were also lower in cut stands. In the harvested stands, the density varied between 14.1 and 22.6 drummers/km2between 1990 and 1992 before the CPR. In 1993, density declined to 10.1 but was reestablished at 21.5 in 1994. Densities did not differ significantly before or after the CPR nor between cut and uncut stands (p > 0.05). After the CPR, the grouse generally established their drumming sites in the periphery of cut areas. There they found lateral cover and canopy closure similar to those measured in control stands by choosing sites where deciduous shrubs were more abundant than in the remainder of the stand. However, the characteristics of the tree stratum were not optimal; their overall density, that of Betulaceae, and that of Salicaceae were higher near drumming sites located in control stands than those in harvested stands. In harvested stands, drumming sites had a lower total basal area of trees, and namely that of deciduous trees, than in control sites. To maintain ruffed grouse populations immediately after cutting in mixed and deciduous stands of public lands, we suggest that CPRs be in 15-ha blocks while maintaining a basal area of at least 7.5 m2/ha, half of which should be in trembling aspen (Populus tremuloides Michx.) and paper birch (Betula papyrifera Marsh.).
Temporal variations of forest floor properties in the Coastal Western Hemlock zone of southern British Columbia
Authors: Fons Jaume , Klinka Karel
Published: April 2011

We examined temporal changes in the forest floor across a zonal chronosequence represented by four stages of stand development: stand initiation ( <= 7 years after disturbance), stem exclusion ( ±40-year-old stands), understory reinitiation ( ±60-year-old stands), and old-growth (>350-year-old) stands. All stages, except the old-growth, had a similar history of disturbance: clear-cutting without subsequent burning and silvicultural treatments. Considering thickness and chemical and biotic properties of the LF and H horizons, the most dissimilar stages were the stand initiation and old-growth, and the most similar stages were the stem exclusion and understory reinitiation. Compared with the old-growth stage, the stand initiation stage had about the same thickness of LF and H horizons and bacterial biomass but lower acidity, C:N ratio, fungal biomass, and soil fauna density and higher N mineralization. The stem exclusion and understory reinitiation stages had, in general, properties intermediate between the stand initiation and old-growth stage, with a gradual increase in acidity, C:N ratio, and fungal and faunal populations. After clear-cutting, the forest floor showed inevitable qualitative and quantitative alterations in response to the open-area climate. At the same time, it showed resilience, as most faunal groups of the old-growth stage were present in the stand initiation stage.
Comparisons of gas exchange parameters and shoot water relations of interior spruce (Picea glauca (Moench) Voss times Picea engelmannii Parry ex Engelm.) clones under repeated soil drought
Authors: Fan Shihe , Grossnickle Steven C
Published: April 2011

Physiological response of interior spruce (Picea glauca (Moench) Voss x Picea engelmannii Parry ex Engelm.) to drought conditions was compared for somatic seedlings from clones G351, T703, N366, and W460. Seedlings were subjected to four cycles of progressive soil drought by withholding water. Changes in net photosynthesis (Pn), stomatal conductance (gwv), and predawn water potentials ( psi pd) were measured during and after each drought cycle. Shoot tissue water relations parameters were measured using pressure-volume analysis at the beginning and end of the fourth drought cycle. When comparing drought cycle 1 with drought cycle 4, clones G351, N366, and T703 showed significantly reduced Pn, but gwv of all clones was not affected. Net photosynthesis and gwv decreased with psi pd more rapidly in clone W460 than in the remaining clones. When rewatered after drought, clone T703 had the most rapid Pn and gwv recovery whereas clone G351 had the slowest recovery of Pn and gwv. Over four drought cycles, all clones photosynthesized at progressively lower psi pd, but adjustments in tissue water relations parameters were marginal. These results implied that gas exchange parameters were more sensitive than shoot tissue water relations parameters in detecting clonal variation in the physiological response of interior spruce under simulated drought conditions.
Airborne detection of southern pine beetle damage using key spectral bands
Authors: Carter Gregory A , Seal Michael R , Haley Tim
Published: April 2011

Damage by the southern pine beetle (SPB) (Dendroctonus frontalis Zimm.) occurs frequently in the southeastern United States and can result in tree death over large areas. A new technique for detection of SPB activity was tested for shortleaf pine (Pinus echinata Mill.) in the Caney Creek Wilderness, Ouachita National Forest, Arkansas. Digital images with 1-m pixel resolution were acquired from a light aircraft in 6- to 10-nm bandwidths centered at wavelengths of 675, 698, and 840 nm. The 675-nm band was selected to yield a maximum contrast between yellow or brown versus green foliage. The 698-nm band was selected based on its high sensitivity to leaf chlorophyll content to enable detection of less severe chlorosis in more recently damaged trees. The 840-nm band was used as a reference band that is not sensitive to chlorophyll. Images acquired within each band were calibrated to percent reflectance based on the known reflectances of a gray scale placard located on the ground. Individual trees with yellow to brown foliage were easily located in the 675- and 698-nm images. Milder chlorosis in more recently damaged pines was detected by a normalized difference vegetation index (NDVI) that was derived from 698- and 840-nm reflectances. Although statistically significant, the contrast of recently infested trees versus undamaged trees was generally visually poor in NDVI or color composite images. This was apparently a result of the inherent variability in leaf chlorophyll content throughout the forest. The increased reflectance near 700 nm characteristic of recent damage likely would be resolved more easily in pine plantations of low species diversity. Images of a NDVI that was based on 675- and 840-nm reflectances produced the strongest contrast between heavily damaged and undamaged trees.
Short-term response of wildlife to clear-cutting in Quebec boreal forest: multiscale effects and management implications
Authors: Potvin François , Courtois Réhaume , Bélanger Louis
Published: April 2011

We studied the short-term response of wildlife to clear-cutting in four blocks (52-114 km2) that were logged in 100- to 250-ha clustered patches. Surveys were conducted, 2 years before and 2 years after logging, to determine the relative abundance of 12 wildlife species, and telemetry data were also gathered on four species. Small mammals, species with the smallest home ranges ([Formula: see text]1 ha), either remained in the clearcut patches or had replacement habitat in the buffer strips. Most species with home ranges up to 25 ha (spruce grouse, Falcipennis canadensis Linné; snowshoe hare, Lepus americanus Erxleben) were excluded from clearcut patches. Species with home ranges [Formula: see text]5 km2 (marten, Martes americana Turton; moose, Alces alces Linné) remained in some residual forest patches scattered throughout clearcuts and in the adjacent uncut forest. In their home range, these two species avoided clearcut patches where the shrub layer and coniferous regeneration were scattered. Because many wildlife species depend on residual forest, the important issue is not the size of clearcut patches but the extent and configuration of the remaining forest. Instead of a clustered distribution of clearcut patches, we propose two harvest scenarios more compatible with integrated wildlife-forest management objectives on a local scale.