bluuebunny/crossref_metadata_2025 huggingface dataset:
Patterns of balsam fir foliar production and growth in relation to defoliation by spruce budworm
Authors: Ostaff Donald P. , MacLean David A.
Published: April 2011

Changes in foliar production caused by spruce budworm (Choristoneurafumiferana (Clem.)) defoliation and patterns of volume increment of surviving trees during and after the outbreak were determined in 20 mature balsam fir (Abiesbalsamea (L.) Mill.) stands on Cape Breton Island, Nova Scotia. Following the cessation of defoliation, the number of shoots increased 4-fold and mean shoot length doubled, resulting in a 12-fold increase in needle biomass. Average specific volume increment declined from 0.17–0.25 to 0.02–0.04 cm3•cm−2•year−1 after 4 years of severe defoliation; maximum increment reduction was 74–92%. Periodic radial increment and volume increment reduction (percent of mean increment in the previous decade) were both significantly related to cumulative (summed current annual) defoliation; a logistic regression equation explained 77% of the variation in volume loss. Differences in growth recovery among trees were determined by the temporal patterns of defoliation, with a 1-year lag before the beginning of volume increment recovery. Following 5 to 8 years of recovery, surviving trees had regained 48–82% of their predefoliation increment; however, absolute volume losses during the outbreak averaged 12–33 dm3/tree, or 32–48%.
Improved estimation of domain totals in forest surveys
Authors: Williams Michael S.
Published: April 2011

The literature on estimating population totals in forest surveys is well developed. However in most practical applications, estimation of subpopulation totals (historically referred to as domains of study) is of equal or greater importance but receives much less attention. In this paper, techniques for estimating totals and variances for domains of study are reviewed and an adjusted estimator, with improved efficiency, is derived for estimating such totals. The properties of the adjusted and traditional estimator were studied using two populations, where each population contained three domains of study. In a simulation study based on probability proportional to size sampling, the adjusted estimator produced standard errors that ranged between 23 and 64% of those of the traditional estimator. No detectable bias of the new estimator was found when estimating the most common domains of study. Some bias was evident for estimates of rare domains of study. A bootstrap variance estimator for both the adjusted and unadjusted estimator produced somewhat biased estimates of the variance for the rare domains of study, with biases ranging between−18.2 and 30.8%.
Response of Taxus times media var. densiformis to inoculation with arbuscular mycorrhizal fungi
Authors: Gemma J N , Koske R E , Roberts E M , Hester S
Published: April 2011

Rooted cuttings of Taxus times media var. densiformis Rehd. were inoculated with the arbuscular mycorrhizal fungi Gigaspora gigantea (Nicol. & Gerd.) Gerd. & Trappe or Glomus intraradices Schenck and Smith and grown for 9-15 months in a greenhouse. At the completion of the experiments, leaves of inoculated plants contained significantly more chlorophyll (1.3-4.1 times as much) than did noninoculated plants. In addition, mycorrhizal plants had root systems that were significantly larger (1.3-1.4 times) and longer (1.7-2.1 times) than nonmycorrhizal plants, and they possessed significantly more branch roots (1.3-2.9 times). No differences in stem diameter and height or shoot dry weight were evident at the end of the experiments, although the number of buds was significantly greater in the cuttings inoculated with G. intraradices after 15 months.
Canopy type, forest floor, predation, and competition influence conifer seedling emergence and early survival in two Minnesota conifer-deciduous forests
Authors: Cornett Meredith W , Puettmann Klaus J , Reich Peter B
Published: April 2011

There is concern that the conifer component of mixed conifer-deciduous forests in the Great Lakes region is on the decline, possibly the result of insufficient conifer regeneration. Limitations on conifer regeneration that occur during the first 18 months of seedling emergence and establishment were examined for Abies balsamea (L.) Mill. and Pinus strobus L. in two mixed conifer-deciduous forest types in northeastern Minnesota. We hypothesized that the removal of potential barriers to regeneration, including forest floor, seed predation, and competition with understory vegetation, will enhance conifer regeneration. We also hypothesized that the importance of the above regeneration barriers, and early regeneration success of each species, will differ beneath deciduous and conifer canopy types. The study was conducted under conifer and deciduous canopy types for two sites of each forest type: Abies balsamea - Populus tremuloides Michx. forest and Thuja occidentalis L. - Betula papyrifera Marsh. Germination experiments were conducted with seeds of A. balsamea and P. strobus. Experimental treatments included forest floor removal, caging to exclude seed predators and herbivory, and weeding to study the effects of understory competition. Abies balsamea and P. strobus responded differently to experimental treatments at different developmental stages. The best conditions for early regeneration of both A. balsamea and P. strobus included reduction of seed predation (p < 0.0001) and competition with understory vegetation (p <= 0.001). Abies balsamea additionally benefited from a conifer overstory (p < 0.0001) and a reduction in thickness of the forest floor (p < 0.01).
Diameter and height distributions in genetically improved Pinus radiata
Authors: Carson S D , Hayes J D
Published: April 2011

Diameter and height distributions for Pinus radiata D. Don trees grown from seed lots representing a range of genetic improvement were compared at midrotation (age 14 or 15) in seven large-plot trials at six sites. In one of the trials, comparisons were made at year 5 and annually from age 8 to 16. These are the first data from plantation conifers comparing tree size distributions of commercially planted seed lots. Differences among seed lots for quadratic mean diameter and mean height were statistically significant and generally reflected the expected level of genetic improvement. Standard deviation, skewness, and kurtosis were not significantly different among seed lots. However, diameter distributions of higher rated seed lots sometimes appeared very slightly more skewed to the right and flatter than the lower rated seed lots, a similar tendency observed as stands age. Models used to predict diameter distribution from stand parameters are not likely to require modification for genetically improved seed lots.
Coarse woody debris in sub-boreal spruce forests of west-central British Columbia
Authors: Clark D F , Kneeshaw D D , Burton P J , Antos J A
Published: April 2011

An evaluation of how coarse woody debris (CWD) changes in quantity and quality during stand development was conducted using a 426-year chronosequence of 71 stands in sub-boreal forests in British Columbia. Additional characteristics of CWD were determined in 14 of the stands. Most stands are fire initiated and input from the predisturbance stand is critical in controlling the amounts and characteristics of CWD within young stands. Log volume declines from over 100 m3/ha in young stands (0-50 years) to just over 60 m3/ha in stands from 51 to 200 years old, and then increases to greater than 140 m3/ha in the oldest (>= 400-year-old) stands. Mean snag basal area is highest (31.6 m2/ha) in young, postfire stands, decreases to a very low value (2.0 m2/ha) in stands 51-100 years old, and then reaches a second maximum (12.1 m2/ha) in stands that are 201-250 years old; it declines slightly in very old stands. The high snag basal area in stands 201-250 years old coincides with the successional transition from lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) to stands dominated by subalpine fir (Abies lasiocarpa (Hook.) Nutt.) and interior spruce (hybrids of Picea glauca (Moench) Voss and Picea engelmannii Parry). Stand age, characteristics of the predisturbance forest, and the disturbance history of stands subsequent to stand initiation all appear to be very important in determining variation in both the quality and quantity of CWD in these sub-boreal forests.
Incorporating cointegration relations in a short-run model of the Finnish sawlog market
Authors: Toppinen Anne
Published: April 2011

This paper reports on the results of a simultaneous equations sawlog market model using monthly data for Finland in 1985-1997. Johansen's multivariate method is used to estimate cointegration vectors, which are then included in a dynamic error-correction model. Rank tests indicate two cointegrating vectors, which is theoretically consistent with the demand and supply equations. In the sawlog demand, the equilibrium is established for sawlog stumpage price and quantity and sawn wood price and capital stock, while the supply function in a perfect capital market entails sawlog price and quantity, real interest rate, and the effect of increasing timber stock as captured by a linear trend. Contrary to earlier findings, stumpage price seems to have a positive effect on sawlog supply, both in the short and long run, while only the long-run price effect is present in the sawlog demand. Disequilibrium in demand is corrected within one quarter, while the speed of adjustment is found to be slow in the sawlog supply.
Responses of boreal conifers to climate fluctuations: indications from tree-ring widths and carbon isotope analyses
Authors: Brooks J Renée , Flanagan Lawrence B , Ehleringer James R
Published: April 2011

Spatial distribution and species composition of the boreal forest are expected to change under predicted climate change scenarios. Current research indicates that water limitations control the southern boundary of the central Canadian boreal forest and temperature limitations control the northern boundary. As part of Boreal Ecosystem - Atmosphere Study (BOREAS), we examined this idea by comparing annual variation in tree-ring widths and carbon isotope ratios ( delta 13C) of tree-ring cellulose with annual climatic parameters in the northern and southern boreal forest. Contrary to expectations, climate correlations with ring widths at the northern and southern sites were similar in black spruce (Picea mariana (Mill.) BSP). Annual growth was favored by cooler and wetter conditions. For jack pine (Pinus banksiana Lamb.), increased temperature and spring precipitation favored annual growth at both sites. In the north, annual growth was negatively correlated with winter precipitation. The delta 13C - climate correlations in Pinus banksiana followed current distribution theories. In the south, potential evapotranspiration explained significant annual delta 13C variation, whereas in the north, winter and growing season precipitation influenced annual delta 13C variations. Our data support the concept that moisture limits the southern range of Pinus banksiana and cold soil temperatures limit the northern extent. However, colder, wetter conditions favored growth of Picea mariana throughout its range. These observations strengthen the concept that species respond individually to climate change, not as a cohesive biome.
Structure and yield of two-aged stands on the Willamette National Forest, Oregon: implications for green tree retention
Authors: Acker S A , Zenner E K , Emmingham W H
Published: April 2011

Green tree retention, a practice based on ecosystem science, has been integrated into forest management as a working hypothesis, requiring research and monitoring to quantify its effects. We undertook a retrospective study of natural, two-aged forest stands on the Willamette National Forest to provide preliminary estimates of the effects of green tree retention on forest structure and yield. Fourteen stands in the western hemlock (Tsuga heterophylla (Raf.) Sarg.) zone (mostly dominated by Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco) were sampled using adjacent, paired plots: one with residual trees over a younger cohort (median age of younger cohort, 97 years) and one with only the younger cohort. The younger cohorts all had much higher densities of trees than typical of local Douglas-fir plantations. Basal area, volume, and mean annual increment (MAI) of the younger cohort all declined with increasing residual tree basal area. These relationships were best described by curvilinear models; the greatest effect per unit of residual tree basal area occurred at low residual tree levels (5-10 m2/ha). For 10 m2/ha residual tree basal area (equivalent to about 12 average (diameter at breast height 105 cm) residual trees per hectare), we predicted a 26% decline in younger cohort MAI (95% confidence interval: -30% to -22%).
Effects of conifer release treatments on the growth and fruit production of Vaccinium spp. in northwestern Ontario
Authors: Moola F M , Mallik A U , Lautenschlager R A
Published: April 2011

Berry production and vegetative recovery of lowbush blueberry (Vaccinium angustifolium Ait.) and velvet leaf blueberry (Vaccinium myrtilloides Michx.) were documented for three growing seasons (1994, 1995, 1996) after brushsaw, single operational and multiple nonoperational Vision® herbicide (active ingredient glyphosate), and control treatments in a jack pine (Pinus banksiana Lamb.) plantation in northwestern Ontario. Vaccinium angustifolium fruit production was significantly (P <= 0.05) reduced by both the single and multiple treatments in all 3 years of the study. Fruit production by V. myrtilloides was significantly (P <= 0.05) reduced only by the multiple treatment. The significant reduction in berry production by V. angustifolium contributed to an overall drop in the availability of blueberries (both species combined) on sprayed clearcuts in 1995 and 1996. Single and multiple treatments also significantly (P <= 0.05) reduced fresh mass and dry mass of total berries in 1995 and 1996. Compared with the controls, reductions in cover for both blueberry species were only significant (P <= 0.05) with the Vision® treatments. In clearcuts where V. angustifolium forms a major component of the Vaccinium spp. cover, the short-term reduction in fruit availability in sprayed areas may be considerable.
Genetic variation in summer gas exchange patterns of interior spruce (Picea glauca (Moench) Voss times Picea engelmannii Parry ex Engelm.)
Authors: Grossnickle Steven C , Fan Shihe
Published: April 2011

Interior spruce (Picea glauca (Moench) Voss x Picea engelmannii Parry ex Engelm.) somatic seedlings from a range of clones were measured for gas exchange processes in relation to summer atmospheric parameters. Carbon isotope composition ( delta 13C) of needles was compared with gas exchange parameters and intrinsic water use efficiency (WUEi). Needle conductance (gwv) decreased as vapour pressure deficit (VPD) increased. Clone T703 had the lowest gwv level across all VPD conditions, with clones G351, N366, and W460 having significantly greater gwv than clone T703 at VPD levels <2.0 kPa. Response of net photosynthesis (Pn) to photosynthetically active radiation (PAR) for all clones showed Pn to increase to PAR levels of around 1000 µmol ·m-2 ·s-1 and then, Pn rates were stable at higher PAR levels. Clones N366 and W460 had significantly greater Pn than clone T703 at all PAR levels. All clones showed Pn to decline as VPD increased, with clone W460 having the highest predicted Pn level across all VPD conditions and significantly greater Pn than clone T703. Higher WUEi was related to an increase in delta 13C, with clone T703 having the highest WUEi and delta 13C, followed by clone W460. Changes in delta 13C, for all clones, indicated a stronger relationship with gwv than with Pn.
Growth, decay, and turnover rates of fine roots of basket willows
Authors: Rytter Rose-Marie , Rytter Lars
Published: April 2011

The aim of the present study was to calculate fine-root turnover rates in stands of basket willow (Salix viminalis L.). Fine-root number was recorded in minirhizotrons in two adjacent short-rotation forest stands. Stand A was a regularly spaced plantation on clay soil. Stand B contained lysimeters, which were inserted in the soil and filled with either clay soil or washed sand. Both stands were irrigated and fertilized daily, to provide near-optimum conditions with respect to water and nutrient availability. The calculations were based on morphological studies and observations in minirhizotrons. Mean fine-root ages of growth and decay phases were calculated from third-order polynomials, and by summing up those phases and adding a short stationary phase, turnover time was obtained. Calculated fine-root turnover rates were 4.95.8 year1 in the plantation and 4.88.1 year1 in the lysimeters. No significant difference in turnover rates was detected between clay and sand substrates. Soil temperature had a significant effect on the decay phase, and in the calculations the data were weighted by soil temperature intervals. The importance of observing fine roots throughout the year is stressed.
Seasonal changes in soil temperature and in the frost hardiness of Scots pine (Pinus sylvestris) roots under subarctic conditions
Authors: Sutinen Marja-Liisa , Ritari Aulis , Holappa Teuvo , Kujala Kauko
Published: April 2011

The seasonal changes in soil temperature and in the frost hardiness of adult Scots pine (Pinus sylvestris L.) trees was studied between September 1991 and February 1993 in a pine forest located in Finnish Lapland. Air and soil (humus layer and 5 cm depth of mineral soil) temperatures were measured continuously every second hour. The frost hardiness of the roots in the humus layer and in the mineral soil (down to 10 cm) was measured by means of the electrolyte-leakage method. The temperature in the humus layer varied between 21.2°C and 3.2°C and in the mineral soil between 21.6°C and 2.4°C. The temperature in the humus layer was continuously slightly colder than in the mineral soil from late August until May. The frost hardiness of the pine roots was lowest (about 5°C) in May and during the first week of September. Frost hardiness stayed at its maximum of about 20°C during November and December and slightly decreased in January and February. During most of the sampling time, the frost hardiness of the roots in the humus layer was greater than in the mineral soil. There was a clear relationship between the soil temperature and the frost hardiness of roots.
The core area concept in forming contiguous areas for long-term forest planning
Authors: Öhman Karin , Eriksson Ljusk Ola
Published: April 2011

The core area concept is proposed as a criterion promoting the formation of contiguous areas of old growth over time in the landscape. Core area is defined as the area of old forest, free of edge effects, where the edge effect is a function of the state of the surrounding habitat. The core area measure is evaluated by solving a long-range planning problem for a landscape consisting of 200 stands, where the net present value of forest management is maximized under the constraint of a certain amount of core area in the landscape over a time horizon of 100 years. Simulated annealing is used as the solution technique. The results indicate that the degree to which stands are clustered depends on the amount of core area demanded and the extent of the edge width. The amount of new core area that is allocated adjacent to existing core area, indicating a continuity of core area formation, is increased with core area demand, the minimum age of old forest, and the existence of a U-shaped initial age structure. The cost of attaining the spatial patterns appears to be low compared with the cost of retaining the old forest.
Elevated temperature but not elevated CO2 affects long-term patterns of stem diameter and height of Douglas-fir seedlings
Authors: Olszyk D , Wise Claudia , VanEss Erica , Tingey David
Published: April 2011

Global climatic change may impact forest productivity, but data are lacking on potential effects of elevated CO2 and temperature on tree growth. We determined changes in shoot growth for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings exposed to ambient or elevated CO2 ( µmol·mol-1), and ambient or elevated temperature . Seedings were grown for 4 years (three complete growing seasons) in outdoor, sunlit chambers. In each season, height growth was initiated earlier and, in two seasons, ceased earlier for elevated compared with ambient temperature trees. Elevated temperature reduced intermediate and final plant heights. Stem diameter growth began earlier each season at the elevated compared with the ambient temperature, but temperature had no affect on final stem diameter. Elevated temperature tended to reduce leaf (p = 0.07) but not woody biomass. Elevated CO2 had no significant effects on stem diameter, height, and leaf or woody biomass, and there were no significant CO2 × temperature interactions. Thus, elevated temperatures (but not elevated CO2) associated with climate change may decrease seedling canopy growth as indicated by reduced height and leaf biomass but have little or no effect on overall woody growth as indicated by stem diameter and woody biomass.
Effects of upper stem measurements on the predictive ability of a variable-exponent taper equation
Authors: Kozak Antal
Published: April 2011

Like several other taper equations, the predictive ability of Kozak's (1988. Can. J. For. Res. 18: 1363-1368) variable-exponent taper equations can also be improved by an additional upper stem outside bark diameter measurement. This study indicated that improvements were small and were mainly restricted to increasing the precision of the estimates. Also, it was demonstrated that if additional diameter measurements are justified, they should be taken between 40 and 50% of the height above breast height for greatest improvement. Measurement errors in upper stem diameters and in their heights above breast height affected both the precision and bias of predictions.
Ionic balance and organic acids in western redcedar, western hemlock, and Douglas-fir seedlings grown in low- and high-N soils
Authors: Graff, Jr. J E , Hermann R K , Zaerr J B
Published: April 2011

Seedlings of western redcedar (Thuja plicata Donn ex. D. Don), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were transplanted into soils with low and high levels of available NO3-(and total N). Current-year foliage was sampled after 10 weeks to determine the effect of N availability on foliar cation-anion balance (C-A) and the concentrations of low molecular weight organic acids of the three species. Carboxylate concentrations were estimated by using the difference between sums of cations and anions (C-A): 750 mequiv.·kg-1for western redcedar, 351 mequiv.·kg-1for western hemlock, and 266 mequiv.·kg-1for Douglas-fir. Quinic acid was a primary constituent, accounting for 40% of the total for western redcedar and 75% for western hemlock and Douglas-fir. Oxalic acid was present in greatest concentration in the foliage of western redcedar (65 mequiv.·kg-1) but was a minor constituent in western hemlock and Douglas-fir. The quantified acids accounted for only 15% of the C-A of western redcedar but >80% of the C-A of western hemlock and Douglas-fir. A considerable portion of the C-A balance not accounted for in redcedar may be associated with the accumulation of CaCO3. Litterfall deposition of CaCO3may lead to the consumption of H+ions and enrichment of exchangeable soil Ca in the rooting zone of long-lived western redcedar trees. No statistically significant differences among the soils were detected with regard to C-A or the concentration of organic acids.
Understory plant community response after 23 years of hardwood control treatments in natural long leaf pine (Pinus palustris) forests
Authors: Kush John S , Meldahl Ralph S , Boyer William D
Published: April 2011

In 1973, a study was established in south-central Alabama, U.S.A., to determine the effects of hardwood control treatments on understory succession and overstory growth in natural stands of longleaf pine (Pinus palustris Mill.). The treatments were seasonal biennial burns and a no-burn check, each combined with three supplemental hardwood control treatments (one-time chemical, periodic mechanical, and untreated check). Green vegetation less than 1 cm DBH and organic litter were destructively sampled to determine the effects of 23 years of treatments on understory vegetation and identify changes in this community since last sampled in 1982. Among the hardwood control treatments, the only significant differences occurred in the shrub and green biomass (total of tree, shrub, woody vine, and herbaceous species masses) component of the understory. There were significant differences for all vegetation components when comparing the burning to no-burn treatment. Green biomass estimates were variable but showed an increase for all but two of the 12 treatment combinations when compared to 1982 biomass. The major change occurred in the accumulation of organic litter, which increased 119% when averaged across all treatments. The chemical treatment did not eliminate any species when compared with the other hardwood control treatments.
Phenology and productivity of saw palmetto (Serenoa repens) in a north Florida slash pine plantation
Authors: Gholz H L , Guerin D N , Cropper W P
Published: April 2011

Phenological observations were used in conjunction with destructive sampling and measurements of plant cover to determine the aboveground seasonal dynamics, annual aboveground net primary production (ANPP), and responses to fertilizer applications of the rhizomatous, perennial, understory species, saw palmetto (Serenoa repens (Bartr.) Small), in a north-central Florida pine ecosystem. Phenology was not significantly affected by the fertilization. Flowering, fruiting, frond initiation, and frond mortality were all highly seasonal, but while flowering was consistent, fruiting occurred in only one of the three seasons studied. Turnover rates of plant biomass averaged 22% per year over the 2 years and treatments, resulting in ANPP values of 11-37 g·m-2per year, with higher values on fertilized plots, which amounted to 1-3% of overstory ANPP.
Growth response of loblolly pine, sweetgum, and water oak in a pine-hardwood density study
Authors: Glover Glenn , Quicke Harold
Published: April 2011

A study was established with loblolly pine (Pinus taeda L.) planted at 1683 trees/ha competing with sweetgum (Liquidambar styraciflua L.), water oak (Quercus nigra L.), or loblolly pine at densities of 0, 1794, 2692, and 5382 trees/ha. The study is a split-split plot with three blocks. Main plots are the three competitor species; subplots are with or without 2 years of herbaceous vegetation control (HVC); and sub-subplots are competitor densities. The study was measured at 6 years after establishment. Pines in pure plots responded to HVC with a mean basal area gain of 1.8 m2/ha (13%). With HVC, basal area increased 2.7 m2/ha (70%) for sweetgum and 2.3 m2/ha (58%) for water oak. Pines in mixed plots did not respond, or responded negatively, to HVC. Pine height, basal area, volume index, and canopy projection were only slightly affected by sweetgum density above zero. Pine characteristics decreased as water oak density increased. Adding sweetgum or water oak to pine reduced total (pine + hardwood) volume index and basal area.
Early seedling demography in balsam fir seedling banks
Authors: Duchesneau Robin , Morin Hubert
Published: April 2011

Following the 1995 mast year, we conducted detailed seedling demography surveys to characterize some ecological factors affecting germination and early establishment in understory balsam fir (Abies balsamea (L.) Mill.) seedling banks and verify if recruitment from a cohort can potentially renew the balsam fir seedling bank. Twenty-five seed traps paired with 32 demography subplots were located in each of four permanent plots and regularly monitored over a 2-year period. Spatial patterns of newly emerged seedlings generally corresponded to those found for seed dispersal. However, at the end of the monitoring period, the spatial pattern of surviving seedlings was independent of the seed dispersal pattern. Seedbed types and understory light environments were the main factors explaining seedling mortality. Sphagnum mosses and decaying wood were the most favorable seedbeds for early establishment. The 0- to 25-cm seedling populations grew in size because of the addition of new recruits. If, in the years to come, mortality rates of the 1995 cohorts were similar to those of already established 0- to 25-cm seedlings, mast years of seed production, at least during endemic periods, would be crucial for recruitment and renewal of balsam fir seedling banks.
Comparative responses of small mammals, vegetation, and food sources to natural regeneration and conifer release treatments in boreal balsam fir stands of Quebec
Authors: Gagné Nancy , Bélanger Louis , Huot Jean
Published: April 2011

Abundance and species diversity of small mammals were compared among three regeneration methods used in boreal balsam fir (Abies balsamea (L.) Mill.) forests. Those methods were natural regeneration after "careful logging" to retain advance regeneration and planting (black spruce, Picea mariana (Mill.) BSP) followed by herbicide (Vision®) release or brushsaw cutting release. Deciduous vegetation was reduced for two growing seasons in both plantation types after treatment, and foliar arthropods decreased for one growing season. In herbicide-treated plantations, red raspberry (Rubus idaeus L.) shrub cover, near-ground vegetation, and production of berries were reduced for two growing seasons. After herbicide release, the abundance of the red-backed vole (Clethrionomys gapperi (Vigors)) was significantly lowered for two growing seasons. This negative effect was associated with reduced cover during the first two post-treatment growing seasons. In the short term, herbicide-treated plantations constitute poorer red-backed vole habitats than brushsaw plantations. In early successional boreal balsam fir stands, planting did not markedly affect small mammals probably because natural regeneration was common in these plantations.
Methods for assessing uncertainty of growth and yield predictions
Authors: Kangas Annika S
Published: April 2011

Good estimates of the precision and accuracy of stand growth and yield predictions are needed in the decision-making process. Future growth and yield are often projected with a complex simulation system, so that these assessments are not easy. The precision of long-term growth and yield predictions has often been estimated through Monte Carlo simulation, combining several error sources with different variances. A simple method to assess the uncertainty of stand growth and yield predictions is to model the observed (past) errors obtained by comparing the observed stand characteristic with the characteristic predicted using the simulation system. Using this model, the uncertainty of future predictions can then be anticipated. Another possibility is to form an elementary model for stand growth (or yield) and use its variance as an assessment of the uncertainty for the simulation system. In this paper, the above-mentioned three methods were used for assessing the uncertainty of a simulation system. These assessments were then compared with the empirical estimates of uncertainty. The three methods were also compared with respect to their data requirements and the capabilities of the methods.
Chondrostereum purpureum as a biological control agent in forest vegetation management. I. Efficacy on speckled alder, red maple, and aspen in eastern Canada
Authors: Pitt D G , Dumas M T , Wall R E , Thompson D G , Lanteigne L , Hintz W , Sampson G , Wagner R G
Published: April 2011

As part of a national initiative, a series of experiments were established to evaluate the field efficacy of the indigenous fungusChondrostereum purpureum (Pers. ex Fr.) Pouzar as a biological agent in woody vegetation control. Separate experiments involving manual cuttings of speckled alder (Alnus rugosa (Du Roi) Spreng.), red maple (Acer rubrum L.), and aspen (Populus tremuloides Michx.) employed a common suite of treatments and randomized complete block design with five replications. Treatments, applied between June 26 and 29, 1995, included two formulations, each combined with two fungus isolates, 2139 from British Columbia and JAM6 from Ontario. Cutting only (no treatment) and stump treatments with triclopyr (Release®) and blank formulations were used as controls. Two growing seasons after treatment, triclopyr provided significantly greater control of target species than C. purpureum. The fungus exhibited its greatest efficacy on alder, resulting in a 72% reduction in stem volume index and 19% clump mortality over untreated controls. On red maple, isolate 2139 provided a 32% reduction in the volume of stump sprouts. On aspen, both isolates of C. purpureum resulted in a 35% reduction in the volume of stump sprouts and isolate 2139 provided an 88% reduction in the volume of root suckers. Efficacy appeared to vary among fungus isolates and target species, while formulation was less important.
The influence of the bamboo Yushania microphylla on regeneration of Abies densa in central Bhutan
Authors: Gratzer G , Rai P B , Glatzel G
Published: April 2011

To assess the impact of a dense understory of the bamboo Yushania microphylla Munro on tree regeneration in monospecific Abies densa Griff. stands of the central Bhutan Himalayas, the age-class distribution of fir regeneration, the microsite preferences, and height growth as well as the relationship between height of the bamboo, gap fraction, and tree seedling density were studied. Seedling densities were much lower on sites with bamboo. Recruitment was more or less continuous, and there was no indication of overall synchronized single-cohort regeneration in bamboo plots. On sites with bamboo understory, the light regime at the forest floor is strongly influenced by the height of the bamboo. A large portion of the variance of tree seedling density could be explained by the height of the bamboo. The mortality of fir seedlings is considerably reduced at elevated microsites. Fir establishment on the forest floor is restricted to sites where bamboo density is low and light levels are higher. On sites with dense, unbrowsed bamboo, light levels are too low for long-term survival of fir seedlings, resulting in a lack of suppressed regeneration with minimal height growth. Because of the absence of this fraction, the average height increment of fir seedlings is higher on sites with bamboo.
Association of pitch moths (Lepidoptera: Sesiidae and Pyralidae) with rust diseases in a lodgepole pine provenance trial
Authors: Rocchini Lynn A , Lewis Kathy J , Lindgren B Staffan , Bennett Robert G
Published: April 2011

A survey in a lodgepole pine, Pinus contorta var. latifolia Engelm., provenance trial showed that the western pine moth, Dioryctria cambiicola (Dyar) (Lepidoptera: Pyralidae), was the most prevalent pitch moth, and stalactiform blister rust, Cronartium coleosporioides Arth., the most prevalent stem rust. Also present were the Douglas-fir pitch moth, Synanthedon novaroensis (Hy. Edwards) (Lepidoptera: Sesiidae), comandra blister rust, Cronartium comandrae Pk., and western gall rust, Endocronartium harknessii J.P. Moore, and the stem canker Atropellis piniphila (Weir). Results from a likelihood ratio test indicated an association of western pine moth with stalactiform blister rust and of Douglas-fir pitch moth with both western gall rust and stalactiform blister rust. Western pine moth attacks are most commonly found along the active edge of stalactiform blister rust cankers, suggesting that the moth larvae derive some specific benefit from the fungus. The association of Douglas-fir pitch moth with the rusts appear to be a result of the physical wounding caused by the fungi, since attacks by this pitch moth are also frequently found at pruning wounds or other injuries.
Estimating a system of nonlinear simultaneous individual tree models for white spruce in boreal mixed-species stands
Authors: Huang Shongming , Titus Stephen J
Published: April 2011

A system of three interdependent, tree-level nonlinear equations was fitted. The system was used in an individual tree simulator to predict total tree height, periodic tree diameter increment, and height increment for white spruce (Picea glauca (Moench) Voss) grown in boreal mixed-species stands in Alberta. Because the variables appeared on the left-hand side of the equations also appeared on the right-hand side of the equations in the system, the system was estimated using nonlinear simultaneous techniques. Testing of cross-equation correlations using the Breusch and Pagan statistic indicated that the error terms of the related equations in the system are significantly correlated, suggesting that the parameter estimates obtained from simultaneous techniques are consistent and asymptotically more efficient than those obtained from ordinary least squares procedures applied to individual equations of the system.
Determination of sample size for estimating ion throughfall deposition under a mixed hardwood forest at the Lake Clair Watershed (Duchesnay, Quebec)
Authors: Houle Daniel , Ouimet Rock , Paquin Raynald , Laflamme Jean-Guy
Published: April 2011

Variability of throughfall volume and ion deposition were measured under a mixed hardwood forest using 36 or 72 collectors from 1988 to 1994 during the growing period (May to October) for 163 events. The ions showing the highest variability in results were (in decreasing order) NH4+, H+, Mg2+, K+, Ca2+, Cl-, Na+, NO3-, and SO42-, based on the median coefficient of variation of deposition. The variability observed was related to the reactivity of the ion in the canopy, with the more reactive ions showing higher spatial variability. The number of collectors required to obtain estimates of throughfall ion depositions within a 10% error and a confidence interval of 95% varied from 21 (SO42-) to 165 (NH4+) on a weekly basis based on events of median variability. The error associated with deposition measurements was decreased considerably from weekly, to monthly, to seasonal deposition (3 months). The number of collectors necessary to measure throughfall deposition depends on the data quality objectives of the study (i.e., error and confidence interval chosen as acceptable), the variability specific to a given ion, and the time period needed to study a given process with adequate temporal resolution. A figure is proposed that may be used as a guideline to determine the number of collectors needed in mixed hardwood forests based on the latter information.
Nitrogen mineralization and nitrification in upland and peatland forest soils in two Canadian Shield catchments
Authors: Devito Kevin J , Westbrook Cherie J , Schiff Sherry L
Published: April 2011

Net mineralization and nitrification in surface forest soils were measured in upland forest stands and valley peatlands using in situ soil incubations at two headwater catchments of Harp Lake, Ontario from July 1995 to October 1996. No difference in either net N mineralization or nitrification was observed between the two adjacent catchments despite differences in catchment N export. Annual rates of net N mineralization in surface 10 cm were higher in forest soils of the deciduous (11.5 ± 3.1 g/m2; mean ± SE) and conifer-mixed (conifer-hardwoods) (13.9 ± 2.3 g/m2) stands than in peatland soils (1.6 ± 0.6 g/m2). Mean annual nitrification rates were higher in deciduous soils (6.6 ± 0.7 g N/m2) than in mixed stands (1.9 ± 0.6 g N/m2) and peatland soils (0.1 ± 0.2 g N/m2). Annual net N mineralization and nitrification were correlated with variations in soil C and N content and moisture associated with different forest stands. Frequent winter incubations indicate that net mineralization and nitrification under snow cover in upland surface soils can contribute as much as 49 and 23% of the annual net production, respectively. The importance of forest vegetation patterns, winter N transformations, and dissolved organic N pools to total N and NO3- cycling and leaching in these catchments is discussed.
No evidence of short-term effects of clear-cutting on artificial nest predation in boreal mixedwood forests
Authors: Cotterill Susan E , Hannon Susan J
Published: April 2011

We examined whether nest predation in unharvested blocks of trembling aspen (Populus tremuloides Michx.) would increase when adjacent stands were clearcut in the boreal mixedwood forest of Alberta, in 1993, 1994, and 1998. Artificial nests placed on the ground and in shrubs were baited with Chinese painted quail (Coturnix chinensis L.) and plasticine eggs, which along with cameras, were used to identify nest predators. Fragmented sites were isolated from continuous forest by clear-cutting in 1994, while control sites remained unfragmented. Overall, predation on ground and shrub nests did not increase in isolated forest patches post-harvest (p = 0.056 and p = 0.085, respectively), nor was there a consistent effect of distance from a clearcut edge (p >= 0.050). Predation on ground nests was higher in 1994 and 1998 compared with 1993 levels (p < 0.001), while predation on shrub nests remained relatively constant over the 3 years (p >= 0.073). Mice, voles, and red squirrels (Tamiasciurus hudsonicus Erxleben) were the main identified predators of ground and shrub nests, respectively. Probability of nest predation could not be consistently predicted by nest site vegetation or adjacent land cover, but was related to predator abundance. However, neither predators nor songbirds congregate at recent clearcut-forest edges, and we conclude that elevated nest predation caused by clear-cutting may not occur in the boreal mixedwood, at least not at current levels of harvest and within 5 years of clear-cutting.
Impact à court terme de l'exploitation forestière sur le tétras du Canada (Falcipennis canadensis)
Authors: Turcotte Francis , Courtois Réhaume , Couture Richard , Ferron Jean
Published: April 2011

Le suivi télémétrique de 35 tétras du Canada (Falcipennis canadensis) 1 an avant coupe forestière et de 22 autres l'année de la coupe montrent que cette espèce est négativement affectée par la coupe à blanc. Après coupe, les tétras se sont réfugiés dans les habitats résiduels, à proximité du domaine vital printanier. Ils furent rencontrés plus souvent dans des peuplements en régénération, à densité arbustive élevée, et dans des milieux improductifs, sélectionnant parmi les habitats disponibles ceux ayant les plus grandes densités arborescentes et les plus faibles densités arbustives. Les déplacements totaux des tétras ont augmenté pendant et après coupe. Les domaines vitaux d'été étaient de 23-41 ha l'année de la coupe contre 13-33 ha l'année précédente (p = 0,07). La superficie des domaines vitaux ne différait pas statistiquement avant (4-21 ha) et après coupe (19-23 ha). La proportion d'individus au repos a diminué après coupe et les comportements d'alerte ont augmenté (p > 0,01). Le taux de survie des tétras a été plus faible l'année de la coupe (S = 0,44 ± 0,02) que l'année précédente (S = 0,75 ± 0,01). Il fut également plus faible après coupe (S = 0,50 ± 0,02) qu'avant les opérations forestières (S = 0,89 ± 0,09), la prédation étant la principale cause de mortalité. La densité des tétras a diminué de 60% après la coupe.
How well can we select undamaged site trees for estimating site index?
Authors: Nigh Gordon D , Love Bobby A
Published: April 2011

The best estimates of site index, an indicator of site productivity, are obtained from site trees. Undamaged site trees should be sampled to obtain unbiased estimates of site index. Two juvenile height growth modelling projects provided us with sufficient data to assess our ability to select undamaged lodgepole pine (Pinus contorta var. latifolia Dougl.) and white spruce (Picea glauca (Moench) Voss) site trees. The sample trees were split open to measure height growth from the terminal bud scars. Splitting the stems also revealed damage that was not visible from the outside of the tree. Over 50% of the lodgepole pine trees and 75% of the white spruce trees had damage, which was much higher than expected. Possible causes of damage are frost and insects. The damage does not significantly reduce the height of the spruce trees, but there is evidence that the heights of the lodgepole pine trees are reduced.
Early understory succession following catastrophic wind damage in a deciduous forest
Authors: Castelli Jeff P , Casper Brenda B , Sullivan Jon J , Latham Roger Earl
Published: April 2011

Early succession was followed in a 2.5-ha gap created by a severe wind storm in a 5.5-ha fragment of eastern North American deciduous forest. Understory vegetation cover by species, light, soil moisture, and levels of several major nutrients were measured in 1 × 2 m census plots 3 years prior to the disturbance. Coincidentally, the storm felled 50-55% of the trees over a portion of these plots. Vegetation cover by species was again measured in all plots 3 years following the disturbance. Species were grouped by growth form, and group cover values used to examine changes in the composition of the vegetation and to determine whether these changes were correlated with any measured predisturbance environmental variables. Given the size of the gap, shade-intolerant tree species were expected to increase but did not, most likely because of repression by the shrub layer. The main response to the disturbance appeared to occur through reorganization of existing vegetation. The value of predisturbance species cover data and limitations of our sample sizes are discussed.
Response of high-elevation forests in the Olympic Mountains to climatic change
Authors: Zolbrod A Nana , Peterson David L
Published: April 2011

The gap model ZELIG was used to examine the effects of increased temperature (2°C) and altered precipitation on high-elevation ecosystems of the Olympic Mountains, Washington, U.S.A. Changes in tree species distribution and abundance, as well as stand biomass, were examined on north and south aspects in the dry northeast (NE) and wet southwest (SW) regions of the Olympics for (i) warmer, (ii) warmer and 20% wetter, and (iii) warmer and 20% drier climatic-change scenarios. Dominant tree species shift upwards 300-600 m in elevation in the SW, with subalpine meadows and Tsuga mertensiana (Bong.) Carr. forests being replaced by Abies amabilis (Dougl.) Forbes forests at higher elevations and A. amabilis forests being replaced by Tsuga heterophylla (Raf.) Sarg. forests at lower elevations. In the NE, drought-tolerant species become dominant approximately 200 m lower than present, with A. lasiocarpa dominating the north aspect and Pinus contorta Dougl. ex Loud. the south aspect. Biomass increases in the SW and generally decreases in the NE, depending on aspect and precipitation regime. This study suggests that species and site-specific responses at mesoscale (e.g., wet vs. dry climatic regime) and microscale (e.g., north vs. south aspect) resolutions must be characterized to quantify the variation in potential effects of climatic change on forest vegetation in mountainous regions.