bluuebunny/crossref_metadata_2025 huggingface dataset:
Canopy carbon and oxygen isotope composition of 9-year-old hoop pine families in relation to seedling carbon isotope composition, growth, field growth performance, and canopy nitrogen concentration
Authors: Prasolova Nina V , Xu Zhihong , Farquhar Graham D , Saffigna Paul G , Dieters Mark J
Published: April 2011

Carbon isotope composition (δ13C), oxygen isotope composition (δ18O), and nitrogen concentration (Nmass) of branchlet tissue at two canopy positions were assessed for glasshouse seedlings and 9-year-old hoop pine (Araucaria cunninghamii Ait. ex D. Don) trees from 22 open-pollinated families grown in 5 blocks of a progeny test at a water-limited and nitrogen-deficient site in southeastern Queensland, Australia. Significant variations in canopy δ13C, δ18O, and Nmass existed among the 9-year-old hoop pine families, with a heritability estimate of 0.72 for branchlet δ13C from the upper inner canopy position. There was significant variation in canopy δ13C of glasshouse seedlings between canopy positions and among the families, with a heritability estimate of 0.66. The canopy δ13C was positively related to canopy Nmass only for the upper outer crown in the field (R = 0.62, p < 0.001). Phenotypic correlations existed between tree height and canopy δ13C (R = 0.370.41, p < 0.001). Strong correlations were found between family canopy δ13C at this site and those at a wetter site and between field canopy δ13C and glasshouse seedling δ13C. The mechanisms of the variation in canopy δ13C are discussed in relation to canopy photosynthetic capacity as reflected in the Nmass and stomatal conductance as indexed by canopy δ18O.
Soil CO2 efflux and root respiration at three sites in a mixed pine and spruce forest: seasonal and diurnal variation
Authors: Widén Britta , Majdi Hooshang
Published: April 2011

Soil CO2 efflux and respiration of excised roots were measured with a LI-COR 6200 at three sites in a mixed forest (60°05'N, 17°3'E), from May to October 1999, both day and night. Fine-root (<5 mm in diameter) respiration was measured at ambient root temperature and soil CO2 partial pressure, and the roots were analysed for nitrogen (N) concentration. Root-density data obtained from soil cores were used to estimate fine-root biomass. Coarse-root respiration was estimated using stand data, literature data, and allometric relationships. Soil CO2 efflux, 3.07.0 µmol·m2·s1, differed between sites but showed no diurnal variation. Maximum values were obtained in July through August. Fine-root respiration, 0.34.7 nmol·g1·s1, decreased after peaking in early July and showed no diurnal variation. The seasonal mean was lowest at the South site, where also root distribution patterns were different and root N concentrations were lower. Fine-root respiration increased with root N concentration; however, the relationship was very weak, since the variation in root N concentration between sites and times of year was small. Both soil CO2 efflux and fine-root respiration increased exponentially with soil and root temperature, respectively, although fine-root respiration was twice as sensitive. The percentage of soil CO2 efflux emanating from roots was 3362% in May, thereafter decreasing to 1216% in October. This, in combination with larger temperature sensitivity for fine-root respiration, is suggested to cause the temperature sensitivity of soil CO2 efflux to diminish over the season.
Potential productivity of aspen cohorts originating from fire, harvesting, and tree-fall gaps on two deposit types in northwestern Quebec
Authors: Paré David , Bergeron Yves , Longpré Marie-Hélène
Published: April 2011

Height growth of trembling aspen (Populus tremuloides Michx.) stands originating from three different disturbance types (fire, clearcut, and tree-fall gap) was compared on two different deposits (glacial till and lacustrine clay) in the Abitibi region in northwestern Quebec using stem analysis techniques. Several soil properties were also measured to investigate relationships between soil properties and aspen growth. Height growth of aspen was not significantly different among stands of different origins, although on both deposits and at all stages of growth, trees originating from fire were the tallest. Differences in total height among stands of different origins were less than 3 m at 50 years of age. The greatest differences in height growth among stands were expected at younger stages likely because of lower light levels for trees originating from gaps at this stage, but the opposite was observed; height growth differences for 5-year intervals were greater for taller trees. Height growth was greater on clay than on till soils but only for trees greater than 15 m. Soil pH and availability of nitrogen and calcium were correlated with aspen height growth on till soils, while only exchangeable calcium was related to this property on clay soils. Fire had beneficial effects on soils, because it increased soil pH and exchangeable cations. However, these effects did not significantly affect tree growth over one or two rotations.
Norms of reaction and adaptational value considered in a tree breeding context
Authors: Gregorius Hans-Rolf , Kleinschmit Jörg RG
Published: April 2011

Separability of genetic from environmental effects on target traits is a central concern of each breeding program. This requires studies of norms of reaction, i.e., responses of genotypes to environmental conditions that potentially participate in the modification of the trait. Yet, in addition to this modifying environmental condition, achievement of the breeding goal can be affected by a second component of the environment, which decides upon the adaptedness of the desired trait expressions. These adaptive environmental conditions may also vary and may be associated in various ways with the modifying conditions with the result that the desired phenotype is adaptively inferior to less desired phenotypes. Therefore, it is important to know the prerequisites under which a consistent phenotypic superiority guaranteed by separability of the genetic effects transforms into consistent adaptational superiority relations among genotypes. After having recalled the system analytic basis of adaptational processes, this problem is tackled with the help of a paradigm model in which photoperiod dynamics modifies growth conclusion in forest trees and first frost decides upon the adaptedness of the time of growth conclusion in terms of the realized annual growth increment. In this paradigm, maximization of growth increment constitutes both the breeding goal and adaptational valuation of the trait "growth conclusion" under the adaptational condition "first frost." The central result of the analysis rests on the definition of a fictitious genotype, whose time of growth conclusion equals the time of first frost, and which thus characterizes the association between modifying and adaptive conditions that guarantees maximum adaptedness. The result then states that separability of the genetic effects on growth conclusion within the set of genotypes enlarged by the fictitious genotype implies consistent adaptive ranking among genotypes. The implications for common breeding practice and its evolutionary consequences are discussed.
Genetic variation in the decay resistance of Scots pine wood against brown rot fungus
Authors: Harju Anni M , Venäläinen Martti , Beuker Egbert , Velling Pirkko , Viitanen Hannu
Published: April 2011

The role of genotype in the durability of Scots pine (Pinus sylvestris L.) wood against decay by brown rot fungus (Coniophora puteana (Schum. ex Fr.) Karst. (strain Bam EBW 15)) was studied in a laboratory test. The wood material was obtained from 32-year-old half-sib progenies of Scots pine. The increment core samples of sapwood and juvenile heartwood were decayed using a modification of the standardized EN 113 method. The mean densities of the sapwood and heartwood samples were 391 and 337 mg·cm3, respectively, and the mean mass losses were 114 and 80 mg·cm3, respectively. The additive genetic components were small compared with the total phenotypic variance, which resulted in small narrow-sense heritabilities in mass loss. The most marked feature was the wide phenotypic variation in mass loss observed in heartwood (range 199 mg·cm3) compared with sapwood (range 72 mg·cm3) samples. Low heritability, together with the relatively high coefficient of additive genetic variation (CVA) in heartwood mass loss, suggests that advances in breeding can only be made through intensive testing in the environments which the studied experiment represents.
Belowground carbon allocation of Rocky Mountain Douglas-fir
Authors: McDowell Nate G , Balster Nick J , Marshall John D
Published: April 2011

Carbon allocation to fine roots and mycorrhizae constitute one of the largest carbon fluxes in forest ecosystems, but these fluxes are also among the most difficult to measure. We measured belowground carbon fluxes in two Pseudotsuga menziesii (Mirb.) Franco var. glauca stands. We used a carbon balance approach to estimate total belowground carbon allocation (TBCA) and carbon allocation to fine-root and mycorrhizal production (NPPfr). The stands differed in belowground biomass because of fertilization treatment 8 years prior. Annual soil flux was 856 and 849 g C·m2·year1for the two stands. Annual root respiration equaled 269 and 333 g C·m2·year1in the low- and high-biomass stand, respectively. TBCA equaled 733 and 710 g C·m2·year1in the low- and high-biomass stand, respectively. Calculated NPPfrequaled 431 g C·m2·year1in the low-biomass stand and 334 g C·m2·year1in the high-biomass stand; equivalent to 59 and 47% of TBCA, respectively. Fine-root and mycorrhizal turnover equaled 1.8 and 0.8 year1in the low- and high-biomass stands, respectively. Belowground carbon allocation appeared to be distributed evenly between respiration and production despite differences in biomass and turnover. Sensitivity analysis indicated the NPPfrestimate is dependent foremost on the annual prediction of soil CO2flux. The carbon balance approach provided a simple nonintrusive method for separating the belowground autotrophic and heterotrophic carbon budget.
Randomly amplified polymorphic DNA linkage relationships in different Norway spruce populations
Authors: Troggio M , Kubisiak T L , Bucci G , Menozzi P
Published: April 2011

We tested the constancy of linkage relationships of randomly amplified polymorphic DNA (RAPD) marker loci used to construct a population-based consensus map in material from an Italian stand of Picea abies (L.) Karst. in 29 individuals from three Norwegian populations. Thirteen marker loci linked in the Italian stand did show a consistent locus ordering in the Norwegian population. The remaining 16 unlinked marker loci were spread over different linkage groups and (or) too far apart both in the population map and in this study. The limited validity of RAPD markers as genomic "hallmarks" resilient across populations is discussed. We also investigated the reliability of RAPD markers; only 58% of the RAPD markers previously used to construct the consensus map in the Italian population were repeatable in the same material. Of the repeatable ones 76.3% were amplified and found polymorphic in 29 megagametophyte sibships from three Norwegian populations.
Snowpack changes around a nickelcopper smelter at Monchegorsk, northwestern Russia
Authors: Kozlov Mikhail V
Published: April 2011

Snow depth in industrial barrens adjacent to the nickelcopper smelter at Monchegorsk (Kola peninsula, northwestern Russia) by the end of the winter was reduced to one-third of the depth observed in weakened and healthy forests located 3065 km from the smelter; this reduction was due to both decline (by one-half) in the amount (mass) of snow and increase in snow density. Since winter precipitation in Monchegorsk was about the same as in an unpolluted locality 56 km south-southwest of the smelter, and snowpack characteristics correlated with site-specific wind speed, the low amount of snow around the smelter is presumably due to snow movement from open windy habitats and enhanced snow evaporation during the wind transport; higher snow densities may be explained by wind-induced compaction of snow particles. Pollution affects snowpack characteristics by modifying wind regime via forest damage; in turn, decline in snow depth influence the growth form and (possibly) performance of trees that managed to survive in heavily polluted habitats. Thus, initial (partially pollution-induced) forest disturbance, through secondary effects, may enhance further disturbance in a positive feedback fashion; therefore, possible ecological effects of pollution-related snowpack changes should be accounted for in field studies conducted along pollution gradients within the forest zone.
Effects of competitor spacing in individual-tree indices of competition
Authors: Ledermann Thomas , Stage Albert R
Published: April 2011

All indices of competition represent effects of distance between competing trees. However, the functional forms of these distance relations differ, because distance interacts with tree size in the many of the indices. In particular, some of the newer indices use vertical angles and crown geometry to define the effect of separation implicitly. Graphical displays showing effects of distance between subject tree and a competitor in published distance-dependent indices of competition are presented to permit visual comparisons of the indices. Nine pairs of subject and competitor crown classes are included for each index. Relation of these distance functions to the function implicit in distance-independent (stand-level) variables included in the growth prediction model is discussed.
Effect of tree flowering and crown position on rooting success of cuttings from 9-year-old black spruce of seedling origin
Authors: Tousignant Denise , Rioux Michel , Villeneuve Michel , Mercier Stéphan
Published: April 2011

Cuttings were taken at different levels in the crown of both flower-bearing and sexually immature 9-year-old black spruce seedlings (Piceamariana (Mill.) B.S.P.). We obtained satisfactory rooting success, despite the relatively old age of the trees. The rooting percentage of the cuttings taken from the lower third of the crown was significantly higher (p < 0.01) than that of the cuttings originating from the middle and top thirds of the crown (53%, 36%, and 29%, respectively). Cuttings from the upper portion of the crown showed persistent signs of advanced maturation, while those from the bottom of the crown regained an almost juvenile appearance after rooting. Surprisingly, the cuttings taken on flower-bearing trees rooted better (p < 0.10) than those taken on sexually immature trees (48% vs. 30%). Large and significant differences were also recorded between individuals of both groups. No significant interaction was found between sexual maturity and crown position of the cuttings for rooting percentage. The effects of maturation on the rate of rooting and the relevance of replacing grafting by rooting for certain purposes are discussed.
Responses of hardwood advance regeneration to seasonal prescribed fires in oak-dominated shelterwood stands
Authors: Brose Patrick H , Van Lear David H
Published: April 2011

Effects of seasonal prescribed fires of varying intensities on density, mortality, stem form, height, and height growth of hardwood advance regeneration were investigated. Three mixed-hardwood stands on productive upland sites were cut using a shelterwood technique, each forming a block of spring burn, summer burn, winter burn, and control treatments. Advance regeneration was inventoried from permanent plots before and after burning. Fires top-killed nearly all hardwood regeneration, forcing the rootstocks to sprout. Fire treatments reduced densities of all hardwood species relative to not burning, with spring and summer fires causing greater density reduction than winter burning. Among species, oak (Quercus spp. L.) and hickory (Carya spp. Nutt.) were more resilient sprouters than yellow-poplar (Liriodendron tulipifera L.) and red maple (Acer rubrum L.), especially as fire intensity increased. All prescribed fires improved oak stem form and stimulated height growth of hickory and oak. Overall, prescribed fires improved oak advance regeneration with spring burning providing the most benefit. This approach of following a shelterwood harvest with prescribed fire may be a viable method of regenerating oak-dominated stands on productive upland sites.
A protein associated with frost hardiness of western white pine is up-regulated by infection in the white pine blister rust pathosystem
Authors: Ekramoddoullah Abul KM , Davidson Joanne J , Taylor Doug W
Published: April 2011

A 19-kDa protein, Pin m III, was recently shown to be associated with overwintering and frost hardiness of western white pine (Pinus monticola Dougl. ex D. Don) seedlings. Here, we report that this protein is up-regulated by the fungus Cronartium ribicola Fisch, the causal agent of white pine blister rust in western white pine trees. Between 1991 and 1994, bark samples of mature western white pine trees (resistant with no stem cankers and susceptible with stem cankers) were collected in winter, spring, and fall. Proteins were extracted and analyzed by Western immunoblot utilizing specific rabbit polyclonal anti-Pin l I (a homologue of Pin m III) antibodies. During all collection dates, but particularly in the spring, susceptible trees had more Pin m III than resistant trees. In July 1995, 43 previously inoculated 7-year-old white pine seedlings were also analyzed. In all susceptible seedlings (cankered) tested, cankered tissue had high levels of Pin m III, and samples collected from the outside edge of the canker margin had low levels of Pin m III; this protein was also detected in some healthy bark of cankered trees. Since the level of Pin m III in healthy white pine trees is normally lowest in summer months, the high level Pin m III in summer samples of infected tissues is a consequence of the fungal infection.
Comparative assessment of genetic variation of young high-elevation lodgepole pine for height and western gall rust resistance across two sites in Alberta
Authors: Yang Rong-Cai , Dhir Narinder K , Barnhardt Leonard K
Published: April 2011

A total of 456 half-sib families of superior lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) trees found mostly in high-elevation natural stands in west-central Alberta were outplanted in 1990 at two geoclimatically different sites, Norris and Redrock, Alberta. The trials were measured at age 6 for survival, height, and incidence and severity of western gall rust (WGR) (Endocronartium harknessii (J.P. Moore) Y. Hiratsuka). Survival at both sites was very similar (85-87%). Mean family height at Redrock was almost 10 cm higher (60.5 cm) than that at Norris (51.0 cm). Mean family WGR incidence was 25% with a range of 0-76% at Norris, but only 1.6% with a range of 0-27% at Redrock. A similar site difference was also observed for WGR severity. Strong site x family interactions were detected for height growth and WGR infection. The interaction for WGR infection did not seem to involve a change in family ranks because there was very little contribution to the interaction variance from lack of perfect genetic correlation between the two sites. The contrasting patterns of family variation in WGR infection across the two sites may be the outcome of epidemiological (environmental) or genetic causes or both.
Effects of a clear-cut harvest on soil respiration in a jack pine - lichen woodland
Authors: Striegl Robert G , Wickland Kimberly P
Published: April 2011

Quantification of the components of ecosystem respiration is essential to understanding carbon (C) cycling of natural and disturbed landscapes. Soil respiration, which includes autotrophic and heterotrophic respiration from throughout the soil profile, is the second largest flux in the global carbon cycle. We measured soil respiration (soil CO2 emission) at an undisturbed mature jack pine (Pinus banksiana Lamb.) stand in Saskatchewan (old jack pine, OJP), and at a formerly continuous portion of the stand that was clear-cut during the previous winter (clear-cut, CC). Tree harvesting reduced soil CO2 emission from ~22.5 to ~9.1 mol CO2 cdot m-2 for the 1994 growing season. OJP was a small net sink of atmospheric CO2, while CC was a net source of CO2. Winter emissions were similar at both sites. Reduction of soil respiration was attributed to disruption of the soil surface and to the death of tree roots. Flux simulations for CC and OJP identify 40% of CO2 emission at the undisturbed OJP site as near-surface respiration, 25% as deep-soil respiration, and 35% as tree-root respiration. The near-surface component was larger than the estimated annual C input to soil, suggesting fast C turnover and no net C accumulation in these boreal uplands in 1994.
Dendroécologie comparée du sapin blanc (Abies alba) et de l'épicéa commun (Picea abies) dans une vallée alpine de France
Authors: Desplanque Carole , Rolland Christian , Michalet Richard
Published: April 2011

A comparative dendroecological study was carried out in an alpine valley of France (Haute-Tarentaise, Savoie) to analyze the climatic influence on the radial growth of the silver fir (Abies alba Mill.) and the Norway spruce (Picea abies Karst.). Ten populations were sampled at three altitudes on two exposures (North and South). For each population, a chronology of ring-width indices was standardized with a 7-year weighted moving average and with a residue chronology by autoregressive modelling. Then, correlation functions were calculated between growth indices standardized with both methods and climate with an iterative process (bootstrap). The climatic window used here covers 3 years, with mean monthly data of precipitation and temperature. The summer is the most important period for the spruce, which shows a transition along the altitude. This species is successively sensitive to drought at the lower level (year n of ring formation), sensitive to the previous hot summer (n - 1) at the intermediate level, and sensitive to the cold the same year (n) at the upper level. Fir growth is favoured by a rainy previous summer (n - 1) and a hot summer n at the highest altitude on northern slopes, with a difference between northern and southern slopes stronger than for spruce. The interspecific comparison reveals that the fir uses soil water more efficiently and is thermophile, whereas the spruce is more sensible to summer drought. The influence of the year preceding ring formation appears with both methods of standardization and seems to show a real physiological effect.
Using catastrophe theory to model wildfire behavior and control
Authors: Hesseln Hayley , Rideout Douglas B , Omi Philip N
Published: April 2011

Forest wildfire managers are obligated to meetecosystem management objectives, such as cost minimization andresource allocation efficiency (J.T. Williams, R.G. Schmidt,R.A., Norum, P.N. Omi, and R.G. Lee. 1993. USDA For. Serv.Staffing Pap. Washington, D.C.), which is difficult because eachobjective is dependent upon wildfire controllability andbehavior. Currently, there is no functional formula that definesthe relationship between wildfire behavior and controllabilityand therefore, no physical basis for efficient economic analysis.This paper seeks to (1) identify environmental factors thatsystematically predict wildfire controllability and the rangeover which sudden changes in fire behavior occur, (2) quantifythe uncertainty of fire behavior in terms of the environmentalfactors, and (3) define a manageable environmental variablethat can be used to determine marginal costs and benefits ofwildfire management activities. We develop the theory and providean illustrative example of a cusp catastrophe using simulatedfire data. Preliminary results suggest that catastrophe theorymay be an effective tool to model wildfire controllability asmeasured by the modeled change in fireline intensity, windspeed,initial fuel moisture and fuel loading. Because the use of fuelloading as a control parameter describes the marginal physicaleffects on wildfire behavior, this framework may prove suitableas the production relationship for future economic analysis. Notethat the model specified in this paper is theoretical and shouldnot be applied until validated.
Genetic parameters in diallel-crossed Scots pine favor heartwood formation breeding objectives
Authors: Fries Anders , Ericsson Tore
Published: April 2011

After 25 years, full-sibs of Scots pine (Pinus sylvestris L.) in a north Swedish progeny test showed an estimated heritability of 0.30 for heartwood diameter at 80 cm above ground. This was equal to the heritability estimate for tree height, although accompanied by a much larger additive genetic coefficient of variation (0.20 compared with 0.06). The heritability estimate for diameter at breast height was about half that for tree height. Strong and positive phenotypic and environmental correlations were assessed between heartwood and the following traits: diameter at breast height, tree height, and branch diameter. The genetic correlation was low and positive at 0.02 between heartwood and diameter at breast height in contrast with 0.27 between heartwood and tree height. The assessed genetic correlations between heartwood and branch diameter and between heartwood and crown length were very weak compared with the phenotypic and, particularly, environmental correlations. This indicates that the association between crown length and heartwood is significant with regard to environmental factors, no matter to what extent they are independently modified by genes. However, crown limit was the trait that showed the strongest genetic correlation with heartwood (0.49). Since no correlations with production traits were unfavorable, we conclude that including heartwood formation capacity in a breeding programmay be done without drawbacks and with good prospects for success.
Role of the cotyledonary tissue in improving low and ultralow temperature tolerance of butternut (Juglanscinerea) embryonic axes
Authors: Beardmore Tannis , Vong Wendy
Published: April 2011

Butternut (Juglans cinerea L.) survival is threatened in North America by the fungus Sirococcus clavigignenti-juglandacearum. To date, there is no control for this fungal disease and long-term seed storage, to ensure survival of the species, is not a viable option. Initially, low (0, 5, 10, 15, and 40°C) and ultralow (196°C, cryopreservation) temperature tolerance of butternut embryonic axes isolated from the nuts collected from one tree was examined. Embryonic axes with approximately 3 mm of cotyledonary tissue attached to the hypocotyl area germinated after exposure to 0, 5, 10, 15, and 40°C for 4 h and to 196°C for 24 h. Percent germination after exposure to 0 and 5°C was 87 and 82%, respectively, and after 10 and 15°C was 29 and 27%, respectively. Thirty-two percent of axes germinated after 40°C, and 36% germinated after exposure to 196°C. Tolerance to 196°C was examined in the embryonic axes isolated from the nuts of 13 other trees. Significant tree-to-tree variation was found in the tolerance of the embryonic axes to low temperature. This variation corresponded to the water content of the embryonic axes; water contents of 4.8% and lower exhibited tolerance to 196°C. Reducing the water content of the embryonic axes by slow desiccation to 4.8% or less resulted in an increased tolerance to 196°C. These results suggest that low and ultralow temperature storage of embryonic axes may be a viable method for butternut ex situ conservation.
Derivations of stand heights from airborne laser scanner data with canopy-based quantile estimators
Authors: Magnussen S , Boudewyn P
Published: April 2011

The distribution of canopy heights obtained with an airborne laser scanner over a field trial with Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) was a function of the vertical distribution of foliage area. Over a wide range of canopy structures, the proportion of laser pulses returned from or above a given reference height was proportional to the fraction of leaf area above it. We hypothesized that the quantile of the laser canopy heights matching in probability the fraction of leaf area above a desired height would be an unbiased estimator of same. This was confirmed in 36 (20 × 20 m) plots and 6 older validation plots. Canopy-based quantiles of the laser canopy height data were within 6% (mean 3%) of the field estimates. Laser and field estimates were strongly correlated (r ~ 0.8), and statistical tests supported the null hypotheses of no difference in mean stand height (P > 0.3). A geometric model successfully predicted the mean difference between the laser canopy heights and the mean tree height. Our results explicate why estimation of stand heights from laser scanner data based on the maximum canopy height value in each cell of a fixed area grid has been successful in practice.
Regenerating white spruce, paper birch, and willow in south-central Alaska
Authors: Cole E C , Newton M , Youngblood A
Published: April 2011

The current spruce bark beetle (Dendroctonus rufipennis Kirby) epidemic in interior Alaska is leaving large expanses of dead spruce with little spruce regeneration. Many of these areas are habitat for moose (Alces alces). To establish spruce regeneration and improve browse production for moose, paper birch (Betula papyrifera Marsh), willow (Salix spp.), and three stocktypes (plug+1 bareroot, and 1+0 plugs from two nurseries) of white spruce (Picea glauca (Moench) Voss) were planted in freshly cutover areas on Fort Richardson, near Anchorage. Four vegetation-management treatments were compared: broadcast site preparation with herbicides, banded site preparation with herbicides, mechanical scarification, and untreated control. Spruce seedlings had the greatest growth in the broadcast site preparation treatment (p < 0.01). Stocktype was the most important factor in spruce growth, with bareroot transplant seedlings being the tallest and largest 5 years after planting (p < 0.001). In the first 3 years, relative stem volume growth was greater for plug seedlings than for bareroot seedlings (p < 0.001). By year 4, relative growth rates were similar among all stocktypes. Treatment effects for paper birch and willow were confounded by moose browsing. Results indicate spruce can be regenerated and moose browse enhanced simultaneously in forests in interior Alaska.
Genetic correlations between growth and growth rhythm observed in a short-term test and performance in long-term field trials of Norway spruce
Authors: Hannerz Mats , Sonesson Johan , Ekberg Inger
Published: April 2011

Genetic parameters were estimated for traits observed in one short-term "farm-field" test and in seven long-term field trials of Norway spruce (Picea abies (L.) Karst.). The trials, located in southern and central Sweden, were based on subsets of 201 open-pollinated families derived from plus trees grafted in seed orchards. Observations of height growth and phenology in the farm-field test were made during years 2-4, and trees in field trials were assessed for height and damage at 9-14 years of age. Narrrow-sense heritabilities for height-growth traits in the field trials varied from 0.05 to 0.47. Heritabilities in the farm-field test were approximately 0.80 for date of bud burst, 0.35 for leader lignification, and 0.20 for frequency of seedlings with free growth. Early bud burst and a high degree of free growth in the farm-field test were genetically correlated with lower height and higher frequency of ramicorns and frost damage in the field trials. Height in the farm-field test was poorly and inconsistently correlated with height in the field. Genetic correlations for final heights among the field trials were usually significant and in the range of 0.7 and above. Correlations did not decline with distance between trials, suggesting that local climate is more important than regional climatic zones when matching site and genotype.
Predicting the number, death, and self-pruning of branches in Scots pine
Authors: Mäkinen Harri , Colin Francis
Published: April 2011

Branchiness of Scots pine (Pinus sylvestris L.) was studied in 19 thinning experiments in southern and central Finland. Data were collected from 229 trees growing on sites of different fertility, stand densities, ages, and canopy positions. The data were used to construct models for (i) the number of new branches on the stem apex, (ii) the probability of a branch being alive, and (iii) the proportion of the actual number of dead branches out of the predicted initial number of branches on the whorls below the crown base. Generalized variance component models were used to separate the stand-, plot-, and tree-level variation in the dependent variables. The number of new branches was closely connected to the height increment of the current year, slightly modified by the height/diameter at breast height ratio (h/DBH). The probability of a branch being alive was connected to its age, tree age, h/DBH, and its relative diameter within the branch whorl. Self-pruning of branches was faster on large trees with long crowns than on thin trees with short crowns. The indices describing the stand density and spatial arrangement of the neighbouring trees around the sample tree reduced the residuals only slightly.
Growth of planted tree seedlings in response to ambient light levels in northwestern interior cedar-hemlock forests of British Columbia
Authors: Coates K Dave , Burton Philip J
Published: April 2011

Insights into field-planted conifer seedling growth were gained by fitting height and diameter growth to relative irradiance over the growing season using Michaelis-Menten functions. There was little difference among tree species (Abies lasiocarpa (Hook.) Nutt., Picea glauca (Moench) Voss × Picea sitchensis (Bong.) Carr., Pinus contorta Dougl. ex Loud., Thuja plicata Donn ex D. Don, Tsuga heterophylla (Raf.) Sarg.) in response to ambient light. No significant differences in whole-plant compensation points were observed among species but the ranking of species' compensation points was consistent with their shade-tolerance ranking. Five years after planting, total size and recent growth rates varied little among species from low to high light, implying an absence of trade-offs in low- and high-light growth strategies. Thuja plicata had the greatest response to increased light under deep shade (<20% relative irradiance). All species increased growth above 40% relative irradiance, with no clear whole-plant light saturation point evident under field conditions. Growth rates at high light were broadly overlapping and varied considerably within species. As expected,Pinus contorta growth exceeded that of other species above 70% relative irradiance, but it also exhibited high growth rates at low light. Greatest variability among species was at intermediate light levels (30-70% relative irradiance) where careful matching of tree species to light environment can maximize growth rates.
A polymerase chain reaction method for detecting dwarf mistletoe infection in Douglas-fir and western larch
Authors: Marler M , Pedersen D , Mitchell-Olds T , Callaway R M
Published: April 2011

Early detection and management of dwarf mistletoe (Arceuthobium spp.) is currently limited by the inability to rapidly detect infection during the 2- to 5-year endophyte phase of the parasite. We describe a polymerase chain reaction (PCR) technique for detecting Arceuthobium douglasii Engelm. and Arceuthobium laricis Engelm. in tissues of its hosts, Pseudotsuga menziesii (Mirb.) Franco and Larix occidentalis Nutt. DNA was extracted from branches of 15 infected and 15 uninfected P. menziesii. The PCR product amplified by using the Arceuthobium specific primer in the rbcL gene from Arceuthobium template DNA was a fragment of 708 pairs of bases in length. This product was amplified from all branches that were visibly infected, but the fragment was not generated from any samples known to be uninfected. The PCR product from conifer DNA was a fragment of 385 pairs of bases in length and was not amplified from pure mistletoe DNA; this was amplified as an internal positive control. The primers developed for P. menziesii and A. douglasii also worked on L. occidentalis and A. laricis. This method detected mistletoe DNA in 7 of 29 P. menziesii branches and 3 of 21 L. occidentalis branches that did not have external symptoms of infection and are presumed to be the result of the endophyte phase. This method provides a useful tool for experimental applications and for managing the spread of dwarf mistletoe.
Indices of interspecific plant competition for Pinus radiata in the central north island of New Zealand
Authors: Richardson Brian , Kimberley Mark O , Ray John W , Coker Graham W
Published: April 2011

Pinus radiata D. Don was grown on its own and with a range of densities of either buddleia (Buddleja davidii Franchet) or broom (Cytisus scoparius L.), two important forest weed species, in a field trial at Rotorua, New Zealand. Tree growth from the time of planting to age 3 was modelled as a function of tree size and a competition modifier. The competition modifier is, in effect, a multiplier that reduces tree growth according to the degree of competition defined by a competition index (CI). A range of CIs, with some sensitivity to both weed and tree growth and development over time, were individually incorporated into the modifier and evaluated. The "best" CI combined measures of weed height relative to tree height, proximity of the weed to the tree, and weed abundance, and was negatively correlated with an index of light availability. For a given value of CI, the effect on tree growth was independent of weed species. For diameter growth, the effect of CI was independent of tree age. However, for height growth the negative effect of a given CI value was much higher in year 3 than in years 1 and 2. This suggest that competition has an immediate effect on diameter but a delayed effect on height growth.
Patterns in height-diameter relationships for selected tree species and sites in eastern Texas
Authors: Fulton Mark R
Published: April 2011

Relationships between tree height and diameter at breast height were described for 15 species across a range of sites in eastern Texas using a two-parameter equation. Maximum height varied significantly from site to site within a species, but the ratio of initial slope to maximum height was generally constant. Sites favoring tall trees of one species tended to favor tall trees of all species, especially among species found in the overstory. The greatest rates of height growth for a given diameter at breast height increment were found among some midstory and understory species.
Ten-year responses of ponderosa pine plantations to repeated vegetation and nutrient control along an environmental gradient
Authors: Powers Robert F , Reynolds Phillip E
Published: April 2011

Factorial combinations of vegetation, nutrient, and insect control treatments were applied repeatedly to three contrasting California plantations of Pinus ponderosa var. ponderosa Dougl. ex Laws. Ten-year findings show that potential productivity is far greater than previously believed. Stem volume gains were linked directly with increases in crown volume. Insect problems were negligible. Vegetation control increased tree growth profoundly on xeric sites but less so on the most mesic. Where soil was both droughty and infertile, growth responses traced primarily to improved soil moisture availability and secondarily to better nutrition. The most fertile site also was droughty, and trees responded only to improved moisture availability. Water was less limiting on the most productive site. There, both fertilizers and herbicides triggered similar, substantive growth increases. Drought from both plant competition and climate reduced stomatal conductance, xylem water potential, and net assimilation rates. Assimilation rates increased linearly with site index, but treatment differences were not apparent once drought had peaked. Fertilization improved water-use efficiency where water stress was not extreme. Advantages in water availability to pines from vegetation control will dissipate as tree crowns close and transpiration rises.
Genetic structure, variability, and mating system in eastern white cedar (Thuja occidentalis) populations of recent origin in an agricultural landscape in southern Quebec
Authors: Lamy Sylvie , Bouchard André , Simon Jean-Pierre
Published: April 2011

The genetic variability, genetic structure, and mating system of six small, isolated eastern white cedar (Thuja occidentalis L.) populations of recent origin from southwestern Quebec were analyzed using cellulose acetate gel electrophoresis of enzymes extracted from haploid megagametophytes. The analysis of 20 loci showed an average polymorphism of 54.2%, a mean of 1.6 alleles per locus, a mean of 1.15 effective alleles per locus, and observed and expected levels of heterozygosity of 0.116 and 0.129, respectively. There were no significant differences among the six populations for these five genetic parameters. Estimated FIS(Wright's fixation indice) values indicated an excess of homozygotes as compared with the expected values under Hardy-Weinberg equilibrium. The average FSTvalue indicated that 7.3% of the total variability could be attributed to differences among the populations. The multiloci estimates of outcrossing rate (tm) were 0.240 and 0.335, respectively, in each of two populations. Our estimates of the relative contribution of consanguineous matings to the total effective selfing rate averaged about 14%. Results suggest that vegetative propagation is the main factor contributing to family substructuring in these populations of recent origin and contrast with those reported for Ontario populations of T. occidentalis sampled in natural forest environments.
Responses of radiata pine clones to varying levels of pasture competition in a semiarid environment
Authors: Mason E G , Kirongo B
Published: April 2011

An experiment comprising seven clones with four levels of weed competition was established on a semiarid site on the Canterbury plains, New Zealand, during September 1996. Previous experiments showed that trees subjected to little competition from weeds did not always respond to their favourable environments, resulting in more variation among individuals subjected to less competition. The aim of this experiment was to determine whether the variable response to competitive environment is partly a genetic effect. The main plots consisted of four levels of competition: no competition and cleared spots: 3.14, 0.75, and 0.03 m2. Within each plot there were 10 individuals of each clone. Trees generally grew more rapidly with increasing amounts of clear ground, but increasing spots beyond 3.14 m2 did not increase growth during the first year. Variation, expressed as coefficient of variation, was greater among trees subjected to more competition. Within clone coefficient of variation was not related to level of competition.
Structure and composition of unmanaged riparian forests in the coastal mountains of Oregon, U.S.A.
Authors: Pabst Robert J , Spies Thomas A
Published: April 2011

We characterized the structure and composition of unmanaged riparian forests in three river basins in Oregon's coastal mountains. Our objective was to evaluate stand attributes at three spatial scales: streamside (site), drainage network (stream order), and basin (subregion). Data on basal area, species composition, snag density, canopy cover, and tree regeneration were collected along transects at 124 sites. Conifer basal area increased with distance from stream, a trend similar among subregions, and was highest at sites along first-order streams. Hardwood basal area was relatively constant with distance from stream and was proportionally higher at sites along second- and third-order streams than at sites along first-order streams. Conifer and hardwood tree regeneration occurred infrequently and varied by topographic position, stream order, and subregion. Conifer regeneration was associated with basal area of shade-tolerant conifers and appeared to be limited by shrub competition. The unmanaged forests we studied were characterized by a patchy mosaic of structure and composition. Hardwoods and shrubs were major components of the near-stream environment in these forests, whereas dominance of conifers was limited to hillslopes. It appears that fine-scale patterns associated with proximity to the stream are influenced by coarser scale factors such as valley-floor width and climate.
Some observations on fitting assumed diameter distributions to horizontal point sampling data
Authors: Gove Jeffrey H
Published: April 2011

This paper revisits the link between assumed diameter distributions arising from horizontal point samples and their unbiased stand-based representation through weighted distribution theory. Examples are presented, which show that the assumption of a common shared parameter set between these two distributional forms, while theoretically valid, may not be reasonable in many operational cases. Simulation results are presented, which relate the conformity (or lack thereof) in these estimates to sampling intensity per point and the underlying shape of the population diameter distribution from which the sample point was drawn. In general, larger sample sizes per point are required to yield reliable parameter estimates than are generally taken for inventory purposes. In addition, a complimentary finding suggests that the more positively skewed the underlying distribution, the more trees per point are required for good parameter estimates.
Effects of residual stand density on growth and volume production in even-aged red maple stands
Authors: Strong Terry F , Erdmann Gayne G
Published: April 2011

The effects of five residual stand densities (9.2, 13.8, 16.1, 18.4 m2/ha, and an unthinned control (27.2 m2/ha)) on10-year stand and crop tree growth and bole quality were studied in an even-aged red maple stand in Michigan. A secondary treatment of removing the understory trees (5-10 cm DBH) was applied on half the plots. Diameter growth was significantly greater in all cutting treatments than in the control. Ten-year diameter growth in the heaviest cut treatment was nearly three times that of the control. The interaction between understory removal treatments and density treatments was significant for net basal area growth. Ingrowth in the heavier cut treatments accounted for a significant portion of net basal area growth in the plots without understory removal. Mortality was highest in the control and lowest in the heavier cut treatments. Epicormic branching significantly reduced clear bole length of crop trees in the heavier cut treatments, especially when the understory was removed. For these reasons, a more conservative first entry thinning level of about 17-18 m²/ha without controlling the understory is recommended for even-aged red maple stands.
Soil CO2evolution and root respiration in 11 year-old loblolly pine (Pinus taeda) plantations as affected by moisture and nutrient availability
Authors: Maier C A , Kress L W
Published: April 2011

We measured soil CO2evolution rates with (Sff) and without (Sms) the forest floor litter and root respiration monthly in 11-year-old loblolly pine (Pinus taeda L.) plantations during the fourth year of fertilization and irrigation treatments. Values of Sffranged from less than 1 µmol·m-2·s-1during the winter to greater than 5 µmol·m-2·s-1in late spring. Average Sffwas significantly greater in unfertilized relative to the fertilized stands; however, there was no difference in average Smsamong treatments. Soil temperature and the mass of the forest floor (litter) explained most of the difference in Sffamong treatments. Soil temperature and volumetric water content accounted for 70% of the seasonal variation in Sff. Annual carbon efflux from the soil averaged 14.1 Mg·ha-1per year for all treatments. Most of the evolved carbon was derived from root respiration (50-73%). Net ecosystem productivity was -1.1 and 6.9 Mg C·ha-1per year for the unfertilized and fertilized stands, respectively. At age 11, the unfertilized stands were functioning as a net carbon source, while fertilized stands were a strong carbon sink. It was concluded that fertilization could decrease the time for a young pine plantation to change from a carbon source to a carbon sink.