bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate change and wildfire in Canada
Authors: Flannigan M. D. , Wagner C. E. Van
Published: July 2007

This study investigates the impact of postulated greenhouse warming on the severity of the forest fire season in Canada. Using CO2 levels that are double those of the present (2 × CO2), simulation results from three general circulation models (Geophysical Fluid Dynamics Laboratory, Goddard Institute for Space Studies, and Oregon State University) were used to calculate the seasonal severity ratings for six stations across Canada. Monthly anomalies from the 2 × CO2 simulation results were superimposed over historical sequences of daily weather. Then, seasonal severity ratings of the present were compared with those for 2 × CO2 using five variations involving temperature, precipitation, and relative humidity. The relationship between seasonal severity rating and annual provincial area burned by wildfire was explored. The results suggest a 46% increase in seasonal severity rating, with a possible similar increase in area burned, in a 2 × CO2 climate.
Refining estimates of carbon released from tropical land-use change
Authors: Hall Charles A. S. , Uhlig James
Published: July 2007

We report the results of incorporating two changes in the data base that we used for our previously published summary estimates of the quantity of carbon released to the atmosphere from tropical land-use change (R.P. Detwiler and C.A.S. Hall. 1988. Science (Washington, D.C.), 239: 42–47). First, and most important, we used new statistical approaches to estimate biomass. Second, we incorporated recent minor modifications in the estimates of land-use change provided by the Food and Agriculture Organization of the United Nations. Our new, best estimate of carbon release for 1980 is 0.58 ± 0.06 Gt/year. The range of 0.06 Gt/year is due only to the statistieal uncertainty associated with the biomass data base and not to the uncertainty associated with other factors. (Our previous high estimate, based on the use of destructively sampled biomass, remains at 1.6 Gt/year). This new estimate for the tropics as a whole is 26% higher than the analogous number by Detwiler and Hall (R.P. Detwiler and C.A.S. Hall. 1988. Science (Washington, D.C.), 239: 42–47). About 7% of this increase in our estimates of carbon release from the tropics is a result of the new estimates of land-use change for open forests; the rest is due to changing estimates of biomass. In addition, we explored further uncertainties in our data base. When we reduced our estimate of the proportion of cut biomass that goes to long-term storage from 16 to 3%, carbon release increased by about 30%. We also examined the hypothesis that shifting cultivation could be ignored in our analyses. When shifting cultivation was not considered at all in our analyses, an underestimate of 20% resulted for the carbon release in 1980 for the entire tropics. The results of using different data sources for particular countries with large areas in shifting cultivation showed larger differences in carbon flux.
Effect of growth rate on specific gravity of East-Liaoning oak (Quercusliaotungensis) wood
Authors: Zhang Shu-Yin , Zhong Yuan
Published: July 2007

The effect of growth rate on the specific gravity of East-Liaoning oak (Quercusliaotungensis Koidz.) wood was studied and statistically compared with the effect of age (ring number from the pith). Results revealed that age is a decisive factor in controlling the specific gravity of wood, while effect of growth rate on specific gravity is statistically less important. Furthermore, the effect of growth rate varies with ring width range, age, and position within one growth ring (earlywood, latewood, or the whole ring). Within narrower ring widths, specific gravity increases rapidly with increasing growth rate, then more slowly as ring width increases, and when ring width is beyond a specific range, specific gravity remains more or less constant. Growth rate shows little effect on specific gravity of juvenile wood, but with increasing age, the effect increases gradually to reach a significant level in mature wood. Growth rate does not affect specific gravity of latewood significantly, but it shows a greater effect on specific gravity of the whole ring.
The impact of Calamagrostiscanadensis on soil thermal regimes after logging in northern Alberta
Authors: Hogg Edward H. , Lieffers Victor J.
Published: July 2007

The grass Calamagrostiscanadensis (Michx.) Nutt. often forms a dense growth after logging in the boreal forest region of western Canada. Mowing treatments were applied experimentally to examine the effects of C. canadensis shoot biomass and litter on soil thermal regimes. In unmowed sites with heavy accumulations of shoot biomass and litter (768 g•m−2), thawing of soil in the spring was delayed by up to 1 month compared with sites subjected to frequent mowing. Mean soil temperature from May to August at the 10-cm depth averaged 3.8 °C warmer in mowed plots than in unmowed plots. Mowing also caused a three- to four-fold increase in the diurnal variation in soil temperature. Based on the results from different mowing treatments, it appeared that the presence of standing dead C. canadensis shoots and litter was more important than living biomass in producing cold soils. Undisturbed sites dominated by Epilobiumangustifolium L. (fireweed), which does not form a persistent litter layer, had warmer soils than unmowed C. canadensis sites. Cold soils could partly explain the poor growth of conifer seedlings that often occurs after planting in grass-dominated boreal sites.
Addition of organic matter and elements to the forest floor of an old-growth Acersaccharum forest in the annual litter fall
Authors: Morrison I. K.
Published: July 2007

Litter fall and its content of N, P, K, Ca, Mg, S, Fe, Mn, Zn, and Cu were measured monthly over a 5-year period in an old-growth Acersaccharum Marsh, stand on a till site in central northern Ontario. Determined were the following: the amount, and the temporal and spatial distributions, of organic matter and elements deposited annually in the different litter fractions; the proportion of elements conserved within the tree phytomass through retranslocation versus that shed in the annual litter fall; and the residence time of litter-transported elements in the forest floor. Element transfer through the annual litter fall was also compared with that by other vectors of transport to the forest floor. Over the study period, total litter fall averaged 3730 kg•ha−1•year−1 (dry weight), with 78% consisting of leaves, 8% of flowers and fruits, and the remaining 14% mainly of twigs, branches, and bark slough. Annual element depositions (kg•ha−1) averaged as follows: N, 40.6; P, 1.8; K, 9.1; Ca, 37.6; Mg, 3.9; S, 3.0; Fe, 0.57; Mn, 2.67; Zn, 0.28; and Cu, 0.03. Turnover time of the forest floor was calculated as 7.4 years. Residence times (years) of elements in the forest floor were as follows: N, 18.3; P, 18.3; K, 1.5; Ca, 6.1; Mg, 6.8; S, 5.1; Fe, 257.2; Mn, 4.8; Zn, 18.1; and Cu, 5.8. Although the turnover time of forest-floor organic matter did not differ appreciably from values reported for A. saccharum forests elsewhere, residence times for elements suggested somewhat slower cycling, probably as a result of reduced uptake related to the advanced age of the stand. Potassium, followed by S, P, and N, were all conserved to a high degree by A. saccharum trees through retranslocation to the tree's perennial parts prior to leaf fall; Cu, Mn, and Mg were conserved to a lesser degree; Zn, Ca, and Fe were conserved very little. In comparing the leaching loss of elements from foliage with quantities conserved through retranslocation and quantities shed in the annual litter fall, the relative orders of magnitude do not give cause for concern that A. saccharum trees risk appreciable leaching losses of base cations, including K, from foliage as a result of acidified precipitation, at least at levels experienced in central northern Ontario during the early 1980s.
Competition affects shoot morphology, growth duration, and relative growth rates of Douglas-fir saplings
Authors: Harrington Timothy B. , Tappeiner II John C.
Published: July 2007

Saplings of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) were grown with and without competition from tanoak (Lithocarpusdensiflorus (Hook. & Arn.) Rehd.) at two forest sites in southwestern Oregon. Competition reduced the following morphological parameters on Douglas-fir shoots: number and size of buds; lengths of shoots, internodes, and needles; number of internodes; and biomass of foliage and wood. Differences in the length and biomass of Douglas-fir shoots were attributed to combined reductions in internode number and internode length (distance between needles), with internode number accounting for most (72–87%) of the variation. The effects of competition from previous years on Douglas-fir growth, as manifested in 1986 bud size or stem circumference, explained 65 and 92% of the variation in 1987 growth of shoots and stem basal area, respectively. The current-year (1987) effects of competition explained an additional 6 and 3%. During the 1986 and 1987 growing seasons, competition limited both the rates and duration of growth of Douglas-fir basal area; for height, only the rates of growth were reduced.
Effects of fertilization and thinning on 8-year growth responses of second-growth Douglas-fir stands
Authors: Stegemoeller K. A. , Chappell H. N.
Published: July 2007

Fertilization of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands generally increased both basal area and volume growth for at least 8 years. Thinning tended to have an even greater effect than fertilization on basal area and volume growth, increasing both on an individual-tree basis. On a land-area basis, however, the removal of growing stock by thinning caused volume growth to be less than that of the control. The magnitude and duration of this negative response was dependent on the level of thinning and the site quality. A significant positive interaction between fertilization and thinning exists. The combined treatment resulted in the greatest absolute basal area and volume increments, and the response became greater than that to fertilizer alone in the 3rd and 4th years, and remained so through at least 8 years.
Exploratory analysis of the variables affecting initial attack hot-spotting containment rate
Authors: Murphy Peter J. , Woodard Paul M. , Quintilio Dennis , Titus Stephen J.
Published: July 2007

Hot-spotting containment rates were determined for 18 fires of various intensities in two common boreal forest cover types: 8 in jack pine (Pinusbanksiana Lamb.) and 10 in black spruce (Piceamariana (Mill.) B.S.P.). Hot-spotting containment rates did not differ significantly between the two cover types. Correlation coefficients showed that hot-spotting containment rates were more closely related to fire behavior than to weather variables measured as part of the Canadian Forest Fire Weather Index System. Hot-spotting containment rate (HCR; m/man-hour) may be predicted based on rate of spread (ROS; m/min) and flame length (FL; m) using the following model: HCR = exp(6.0140 – 0.1830ROS – 0.1201FL). This model was fitted using weighted nonlinear regression; the R2-value was 0.76.
Restriction fragment length polymorphism mapping in conifers and applications to forest genetics and tree improvement
Authors: Neale David B. , Williams Claire G.
Published: July 2007

It is now technically possible to construct high-density restriction fragment length polymorphism maps for almost any conifer. Hundreds of new genetic markers will become available for forest genetics research and tree-improvement applications. Having a large number of genetic markers will improve efficiency in studies in which isozymes or other markers have traditionally been applied (e.g., genetic variation in populations, paternity analysis, varietal identification, and seed-orchard efficiency). High-density restriction fragment length polymorphism maps may make it possible to (i) identify quantitative trait loci and (ii) practice marker-assisted selection in conifer breeding.
Prescribed-fire effects on fine-root and tree mortality in old-growth ponderosa pine
Authors: Swezy D. Michael , Agee James K.
Published: July 2007

Old-growth Pinusponderosa Dougl. stands were surveyed at Crater Lake National Park to investigate potential accelerated mortality of large pines due to prescribed burning. Mortality of P. ponderosa greater than 22 cm diameter at breast height was higher in burned areas (19.5%) than in unburned areas (6.6%), and early-season burns had over 30% mortality. Mortality was associated with fire severity, as measured by scorch height and ground char, season of burning, and tree vigor. Pines of high, moderate, and low vigor were subjected to a prescribed burn in June; half of the trees had debris raked from tree bases as an additional treatment. Lethal heat loads (>60 °C) occurred in >75% of samples at the soil surface and at 5 cm soil depth, with duration exceeding 5 h. Burning reduced fine-root dry weight 50–75% 1 and 5 months after burning; raking and burning reduced fine-root dry weight more than burning alone after 1 month and had similar effects to burning after 5 months. A low-vigor tree that had been raked and burned died by the beginning of the fourth dry season after burning. Present fuel loads may be too high to burn during spring if old-growth P. ponderosa are to be protected.
A ratio estimator for bias correction in logarithmic regressions
Authors: Snowdon P.
Published: July 2007

It is recommended that the proportional bias in logarithmic regressions be estimated from the ratio of the arithmetic sample mean and the mean of the back-transformed predicted values from the regression. Under the assumption of a lognormal distribution of errors, the conditions for application of this ratio estimator are optimal. A simulated sampling study has shown that this method gives more reliable results than the methods recommended by Baskerville (G.L. Baskerville. 1972. Can. J. For. Res. 2: 49–53) or that derived by Finney (D.J. Finney. 1941. J. R. Stat. Soc. 7(Suppl): 55–61). The new method is also less sensitive to departures from the assumption of a lognormal distribution than the other two methods.
Mycorrhizal status of mature red spruce (Picearubens) in mesic and wetland sites of northwestern New Jersey
Authors: Glenn Marian G. , Wagner Wendy S. , Webb Sara L.
Published: July 2007

During the past 2 decades red spruce (Picearubens Sarg.) has exhibited growth decline throughout its range. Examination of roots of affected trees in many locations has shown death of fine feeder roots. This study examined the mycorrhizae of red spruce in New Jersey, where it is rare. At two localities just below the Kittatinny Ridge in northwestern New Jersey (elevation 425 m), samples of eight long roots from 40 trees were examined, half from mesic and half from wetland areas. All trees sampled showed >60% ectomycorrhizal tips (average, 89%, sd = 0.17). All mycorrhizae were monopodial. Three morphotypes predominated at both sites. Cenococcumgeophilum Fr. colonized over 92% of the sampled trees and accounted for an average of 36% of ectomycorrhizal tips per tree. Ninety percent of trees had plump, pallid mycorrhizae with a smooth mantle, which ranged in color from beige to reddish brown. All wetland trees, but only 40% of the mesic trees, exhibited mycorrhizae with a diffuse network of extramatrical hyphae and a sheathed white tip. Other morphotypes were present in 15–20% of trees. These minor morphotypes were more abundant and more diverse on trees with low levels of colonization by C. geophilum and the white-tip morphotype. There was more variation in level and type of colonization between trees than within individual trees.
Water potential in ponderosa pine stands of different growing-stock levels
Authors: Schmid J. M. , Mata S. A. , Watkins R. K. , Kaufmann M. R.
Published: July 2007

Water potential was measured in five ponderosa pine (Pinusponderosa Laws.) in each of four stands of different growing-stock levels at two locations in the Black Hills of South Dakota. Mean water potentials at dawn and midday varied significantly among growing-stock levels at one location, but differences were not consistent. Mean dawn and midday water potentials within growing-stock levels significantly decreased during the summer but showed minor increases during the overall decline. Stress levels were considered high enough to influence physiological functioning and, therefore, influence susceptibility to mountain pine beetle (Dendroctonusponderosae Hopk.) attack. Mountain pine beetle infestations did not develop within the stressed stands, which suggests that resistance may be only one factor in the outbreak scenario.
A three-stage heuristic procedure for allocating spatially and temporally feasible cutting rights on public lands
Authors: Nelson J. D. , Howard A. F.
Published: July 2007

A three-stage heuristic procedure is described for allocating spatially and temporally feasible timber harvesting rights among competing operators. Within the forest, subzones that contain cut blocks are defined, a harvest schedule is generated, and then these zones are allocated to individual mills. In the first stage, a random search algorithm is used at the forest level to schedule cut blocks so that adjacency constraints and temporal volume flows are satisfied. In the second stage, zones are assigned to deficit mills using a least squares procedure that minimizes the deviations from specified targets. Multiple outputs can be included in the process through a normalization and goal-weighting technique. In the third stage, a ranking procedure that minimizes the total deviations from all targets is used to select the best solution from the set of feasible alternatives that was generated in stage 2. The three-stage heuristic procedure is demonstrated on a sample problem containing 20 zones, 430 cut blocks, three mills, and a 100-year planning horizon. Over 200 feasible alternatives to the allocation problem were found within a relatively short time. The three-stage procedure provides a useful framework for analyzing resource trade-offs among competing users.
Nutrient cycling in red spruce forests of the Great Smoky Mountains
Authors: Johnson Dale W. , Miegroet Helga Van , Lindberg Steven E. , Todd Donald E. , Harrison Robert B.
Published: July 2007

Nutrient distributions, concentrations, and fluxes in two red spruce (Picearubens Sarg.) stands in the Great Smoky Mountains are described and used to evaluate various hypotheses for recent decline of this species. These forests, like others in the southern Appalachians, were relatively rich in N and low in base cation status. The combination of high atmospheric N and S deposition, little or no N or S retention, relatively high N mineralization, and extremely acid soils caused soil solutions to be dominated by NO3−, SO42−, Al, and H+. Soil solution Al in these sites (most of which was in monomeric form) occasionally reached levels noted to inhibit base cation uptake and root growth in solution culture studies. These pulses of Al were driven by pulses of NO3− and, to a lesser extent, SO42− in soil solution. However, fine roots were present at depths of up to 60 cm in the mineral soil, indicating that Al concentrations had not become consistently toxic to roots. Solution fluxes (both throughfall and soil leaching) exceeded litter-fall fluxes for all the macronutrients at both sites, a typical situation for K and S, but most unusual for N, P, Ca, and Mg. There are significant implications of these fluxes and of the apparent net uptake of N by foliage in terms of how vegetation uptake and translocation are calculated. Some new formulations are suggested, but measurement errors in systems with such a predominance of hydrologic fluxes make foliar leaching and, therefore, uptake and translocation calculations extremely uncertain. Although there are no outward signs of decline in these forests (other than balsam fir (Abiesbalsamea (L.) Mill.) mortality due to the balsam woolly adelgid (Adelgespiceae (Ratz.))), the high rates of NO3− leaching rates and the borderline soil solution Al values suggest that these systems are under stress. Whether these factors actually lead to a dieback or growth decline remains to be seen.
Interspecific competition and other factors influencing the performance of Douglas-fir saplings in the Oregon Coast Range
Authors: Wagner Robert G. , Radosevich S. R.
Published: July 2007

Regression models describing total height, stem diameter, stem volume index, and crown volume index of individual 4- to 9-year-old saplings of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) were developed from a retrospective analysis of two site-preparation experiments. The models, which accounted for between 64 and 73% of the variation in individual tree size, integrate environmental and morphological factors that can influence the performance of Douglas-fir saplings into one set of equations. Interspecific competition and amount of animal damage were negatively correlated with tree size. Tree age, 1st-year height, and the use of prescribed burning were positively correlated with tree size. When factors were held constant, trees were largest on steep southeast slopes. The models indicated that tree age, competing vegetation, animal damage, and initial seedling size had a dominant influence on the performance of Douglas-fir saplings, while prescribed burning and topography were of relatively minor importance.
The verification of the heat pulse velocity technique for estimating sap flow in Eucalyptusgrandis
Authors: Olbrich Bernard W.
Published: July 2007

The heat pulse velocity technique was verified on a diffuse porous hardwood, Eucalyptusgrandis Hill ex. Maiden, using the cut-tree method. The heat pulse velocity apparatus accurately reflected sap flow in the stems of 3-year-old trees and of a 16-year-old tree. Measured sap flow was found to be particularly sensitive to errors in the estimation of the wound size and probe separation. Four probes, each providing a point estimate of heat pulse velocity, were sufficient to estimate sap flow in young trees, but a minimum of eight was needed for trees larger than about 20 cm in diameter. For the successful field application of the heat pulse velocity technique on standing E. grandis trees, it is necessary to wait 5 days after implanting the probes to enable tyloses to form, which facilitates wound size measurement. This technique is recommended for the accurate and rapid measurement of water use by E. grandis and other similar plantation tree species.
Foliar terpenes of a putative hybrid swarm (Larixoccidentalis × Larixlyallii) in western Montana
Authors: Carlson Clinton E. , Cates Rex G. , Spencer Stanley C.
Published: July 2007

Foliar terpenes and unidentified volatiles differed significantly between western larch (Larixoccidentalis Nutt.) and alpine larch (Larixlyallii Pari.) populations and were useful in identifying putative hybrids at a site where the species are sympatric. Camphene, sabinene, β-pinene, limonene, β-caryophyllene, β-cubebene, four unidentified volatiles, total volatile concentration, and terpene evenness were significantly different (p ≤ 0.05) between the parental populations. Linear discriminant functions for these terpenes and volatiles were developed for species classes (alpine larch, western larch, and hybrids) previously identified by morphological features. Of 15 trees judged to be hybrids based on morphology, 12 were classified as hybrids by the discriminant functions. All of the alpine larch (n = 10) and western larch (n = 10) in the parental populations were correctly classified by the terpenes. Foliar terpenes appear to be under tight genetic control in the parent species but sort out in the hybrids. Basal area growth of two of the putative hybrids was much greater than growth of either alpine or western larch on the sympatric site, suggesting heterosis. Concentration of ocimene was threefold higher in one of the fast-growing hybrids than in the parental types, suggesting heterosis at the biochemical level.
Relationship between sugar maple budburst phenology and pear thrips damage
Authors: Kolb T. E. , Teulon D. A. J.
Published: July 2007

The relationship between budburst phenology and damage by the pear thrips (Taeniothripsinconsequens (Uzel) (Thysanoptera: Thripidae)) to sugar maple (Acersaccharum Marsh.) foliage was investigated in two studies. In the first study, seedlings in cages were exposed to adult thrips at different stages of budburst. Compared with uninfested control seedlings, introduction of five adult thrips per bud reduced total leaf area and average leaf size, and caused chlorosis, tattering, and cupping of leaves. Leaf area reduction and damage symptoms were greater for seedlings exposed to thrips when leaf margins were first visible at the tip of the bud compared with earlier and later stages of budburst. In the second study, budburst date and number of thrips oviposition sites on leaves (an index of thrips activity) were measured in a common-garden test of maple saplings from open-pollinated families. Thrips activity was greater on early-breaking than late-breaking buds. Date of opening for these early-breaking buds coincided closely with peak capture of flying thrips. Both budburst date and number of oviposition sites on leaves differed among families. Sugar maple genotypes with late budburst escaped heavy thrips damage. The results indicate that timing of vegetative budburst in sugar maple can influence the degree of thrips damage.
Survival of Inonotustomentosus in stumps and subsequent infection of young stands in north central British Columbia
Authors: Lewis Katherine J. , Hansen Everett M.
Published: July 2007

Distribution of tomentosus root disease in spruce (Piceaglauca (Moench) Voss and P. glauca × engelmannii Engelm.) and pine (Pinusconforta var. latifolia Engelm.) stumps in 1- to 30-year-old harvest units, survival of Inonotustomentosus (FR) Teng in stumps, and infection of regeneration trees were examined by transect surveys and root excavations. The number of diseased stumps ranged from 8 to 71 per hectare (2.1–27.5%); these were in patches, commonly two to three stumps each. Viable mycelium was found in 80 and 53% of the 30-year-old spruce and pine stumps, respectively. Distal growth by I. tomentosus in roots ceased shortly after harvest. Narrow decay and stain columns were observed in 1- and 2-year-old spruce stumps. In older stumps, the fungus had colonized the sapwood and bark. In pine, colonization of the bark and cambium was common at all stump ages. Spruce stumps, with longer, horizontally oriented roots and a greater percentage of colonized roots, caused more infections of regeneration than pine stumps (14 and 5%, respectively, of the five regeneration trees closest to each stump). Regeneration trees had a 25% chance of infection if planted within 2 m of decayed spruce stumps and 0.5 m of decayed pine stumps. The probability of infection decreased to 10% at 3.75 and 2.75 m from spruce and pine stumps, respectively. Both spruce and pine regeneration were infected, often at points of disruption in the bark, such as a feeder root or root branch.
Height growth of young Pacific silver fir and noble fir established on clearcuts in the Pacific silver fir zone of western Washington
Authors: Murray Marshall D. , Coble Dean , Curtis Robert O.
Published: July 2007

Stem analyses were done on young (20–30 years at breast height) Pacific silver fir (Abiesamabilis (Dougl.) Forbes) and noble fir (Abiesprocera Rehd.) trees established after clear-cut harvesting of old stands in the Pacific silver fir zone of western Washington. Early height-growth patterns and heights attained at 20 years breast-height age were compared with existing data and curves derived from old stands, and among plant associations and elevations. Early growth of Pacific silver fir and noble fir on recent clearcuts was more rapid than would be expected on the basis of existing data derived from old trees. We hypothesize that the more rapid growth of recently established stands represents the combined result of several factors, including less competition, possible climatic change, exclusion of poorer sites from the new sample, and bias associated with past shifts in competitive status of the old trees used to construct height-growth curves from stem analyses. Early height growth (to a breast-height age of 20) is strongly associated with elevation and with plant association groupings.
Effects of repeated stress on turgor pressure and cell elasticity changes in black spruce seedlings
Authors: Blake T. J. , Bevilacqua E. , Zwiazek Janusz J.
Published: July 2007

One-year-old black spruce (Piceamariana (Mill.) B.S.P.) seedlings were preconditioned by exposing them to either one or two dehydration–rehydration cycles by using the osmoticum polyethylene glycol 3350. Preconditioned and unconditioned seedlings were then subjected to a more severe osmotic (water) stress by exposing them to a higher concentration of polyethylene glycol. Effects of repeated dehydration–rehydration cycles on cell-water relations were studied after 3, 7, and 13 days of stress relief using pressure–volume curve analysis. Repeated dehydration–rehydration cycles caused a cumulative increase in turgor potentials at full saturation. In these preconditioned plants there was also a progressive lowering of osmotic potentials and relative water contents at zero turgor, which increased over time with stress relief. The decline in osmotic potentials at zero turgor in osmotically stressed black spruce was associated with increased cell wall relaxation, followed by increased turgor potentials, in preconditioned but not in unconditioned seedlings. Saturated osmotic potentials were not altered by repeated, short-term conditioning stresses, suggesting that tissue elasticity was more important for turgor regulation than osmotic adjustment.
Reproductive-cycle plasticity in yellow-cedar (Chamaecyparisnootkatensis)
Authors: El-Kassaby Y. A. , Maze J. , MacLeod D. A. , Banerjee S.
Published: July 2007

In 1987, a study was initiated to determine the properties of seed from apparently premature cones of yellow-cedar (Chamaecyparisnootkatensis (D. Don) Spach) on southwestern Vancouver Island. After pollination with fresh pollen in February, all cones showed signs of maturation (i.e., drying and shedding) by December. Samples of these 1-year-old cones were collected for seed extraction and germination tests. Germination ranged between 10 and 42% for isolated cones (i.e., bagged) and between 0 and 25% for unisolated cones. Similar germination results were obtained for the 1988 and 1989 cone crops. Anatomical observations revealed that the 10-month-old embryos were similar in both size and shape to embryos from 2-year-old seeds. It was concluded that transplanting yellow-cedar trees to warmer, low-elevation sites enabled seed cones to continue development without significant delay caused by dormancy induced by cold temperatures at higher elevations. This alteration of normal phenology reflects the impact of environmental contingencies on development.
Performance of Pinusponderosa and Pinusjeffreyi provenances in New Zealand
Authors: Burdon R. D. , Low C. B.
Published: July 2007

Provenance trials were assessed at age 22–24 years at four sites: (1) moist oceanic; (2) moist, semicontinental; and (3–4) dry, semicontinental. The trials at sites 2 and 3 were the main ones, involving nearly 40 provenances of Pinusponderosa Laws. and five of Pinusjeffreyi Grev. & Balf. The P. ponderosa covered from 36°N northwards in the west of its natural range, with 12 provenances in northern and central Sierra Nevada. Past data on Dothistroma blight came from two additional sites. Large provenance differences reflected both relatively discrete races and superimposed clinal patterns. The main divisions of P. ponderosa were (in addition to the eastern variety, scopulorum) as follows: the North Plateau race, east of the Cascade Range extending northwards therefrom; and the Pacific race, in the Sierra Nevada, Coast Ranges, and western Cascade Range. However, there was an apparent transition zone east of the southern Cascade Range, with some Pinuswashoensis Mason & Stockwell south of there. Apart from previously reported differences, the North Plateau race showed better Dothistroma resistance and abundant anthocyanin in cones. Within the Pacific race, Sierra Nevada material suffered more Dothistroma blight, while the northern provenances had more cone anthocyanin. Strong provenance–site interaction occurred for growth, which related largely to differences among races in relative performance at different sites. On the moist sites, height showed very close negative correlations with altitude of origin adjusted for latitude, low-altitude provenances from Sierra Nevada and the Coast Ranges being the tallest. Stem diameter at those sites, while also showing close negative correlations with latitude-adjusted altitude, showed additional effects of race, North Plateau tending to have smaller diameters relative to adjusted altitude. However, at the dry site 3, where growth was less, North Plateau provenances ranked much better; they survived well and included the tallest lot, although diameters still were less than in the Pacific race. Wood density averaged ca. 350 kg/m3 in rings 6–15 from the pith, with very minor differences between sites; this being less than in rings 1–5 and much less than in outer-wood of adjoining Pinusradiata D. Don. The North Plateau race had slightly higher density, particularly in rings 11–15. Some between-provenance variation existed within races, but with no clear pattern. Provenance–site interaction was generally minor. The P. jeffreyi provenances were always among the slowest growing. The one Coast Ranges provenance was distinct from others. Also it grew better relative to the others on the moister sites and had evidently hybridized with P. ponderosa.
Determination of nitrogen, lignin, and cellulose content of decomposing leaf material by near infrared reflectance spectroscopy
Authors: McLellan Toni M. , Aber John D. , Martin Mary E. , Melillo Jerry M. , Nadelhoffer Knute J.
Published: July 2007

We report the results of a study of the near infrared reflectance spectra of decaying forest foliage. During the decay process, a broad absorbance feature develops in the 1100–2000 nm region of the near infrared spectrum. The magnitude of this feature is directly related to the age of the material (or to degree of decomposition) and may be useful in determining degree of decay in field samples. More specifically, multiple linear regression equations derived from second-derivative near infrared reflectance spectra are presented that predict the concentrations of nitrogen, lignin, and cellulose in decaying foliage. We conclude that near infrared reflectance spectroscopy is a very viable and attractive method for the simultaneous determination of these components in decaying foliage.
Pericarp splitting after aerated water soak can be used as an indicator of red oak seed quality
Authors: Cooper Chris , Struve Daniel K. , Bennett Mark A.
Published: July 2007

Two studies were conducted to determine if pericarp splitting following an aerated water soak treatment can be used as an indicator of red oak (Quercusrubra L.) seed quality in seeds subjected or not subjected to cold stratification. In the first study, stratified red oak acorns from three open-pollinated half-sib families were treated with a 10-day aerated soak in tap water (aerated water soak treatment) and grouped into acorns with split and unsplit pericarps before conducting germination tests. Acorns stored at 2 °C during the aerated water soak treatment served as a control. Treated acorns with split pericarps had significantly greater germination capacity and uniformity than treated acorns without split pericarps. In the second study, acorns from four half-sib families were either given the aerated water soak treatment or not in October (unstratified) and in February (stratified), and a germination test was conducted. Pericarp splitting and germination were poor in unstratified seeds and high in stratified seeds. Correlations between percentage of pericarp splitting after an October aerated water soak treatment and germination completeness and uniformity in a February test were not significant. For stratified red oak seed, the aerated water soak treatment offers a fast (results can be obtained in 10 days rather than 14 to 28 days) and simple alternative to present germination tests. Also, the presence of a split pericarp following an aerated water soak treatment is a nondestructive method for identifying high-quality seed before sowing. The aerated water soak treatment is unsatisfactory for determining seed quality in unstratified red oak seed.
Polyamines in leaves and roots of Populusmaximowiczii grown in differing levels of potassium and phosphorus
Authors: Houman Fei , Godbold Douglas L. , Majcherczyk Andrzej , Shasheng Wang , Hüttermann Aloys
Published: July 2007

Effects of K and P deficiency on polyamines (putrescine, spermine, spermidine, and agmatine) in leaves and roots were investigated in poplar (Populusmaximowiczii Henry) cuttings growing in half-strength Hoagland solution with varying levels of K (0, 0.3, and 3 mM) and P (0, 0.05, and 0.5 mM). Putrescine contents increased in the leaves of plants grown without K and in roots of plants grown in 0.3 mM K and without K. In the absence of K, the putrescine levels in the roots and leaves were 80 and 25 times, respectively, those of the control (3 mM K). The zero-P treatment increased the putrescine content in the leaves and decreased the putrescine content in the roots. The accumulation of putrescine did not appear to be regulated solely by the K status of the plants. The spermine content in the leaves of 0.3 mM K and zero-P treatments decreased compared with the control, as did spermine in the leaves of the zero-P treatment. The spermine content in the leaves of 0.05 mM P treatment was similar to that of the control (0.5 mM P). This work shows that in poplar polyamine levels in leaves and roots are strongly influenced by the nutrient status of the plants.
Variations de la régénération préétablie dans les sapinières boréales en fonction de leurs caractéristiques écologiques
Authors: Côté Sylvie , Bélanger Louis
Published: July 2007

The renewal of boreal fir stands after harvesting is related to the abundance of fir advanced regeneration. The objective of this study was to compare the advanced regeneration in 45-years-old balsam fir stands of second growth to determine if ecological site conditions could explain some regeneration problems noted in the balsam fir – white birch ecoclimatic domain. Seven ecological phases were studied; these are among the most common in the Laurentians north of Québec. On the basis of fir seedling densities (2 years old and more), three groups could be distinguished using a cluster analysis method for grouping means. Dry balsam fir – herb-and-moss type on well drained tills formed a first group characterized with very high seedling densities (> 60 000 seedlings/ha). A second group, characterized with high seedling densities (25 000 – 40 000 seedlings/ha), was constituted of three phases with an important moss cover:the mesic balsam fir – moss-and-herb type on moderately well drained tills, the humid balsam fir – moss-and-herb type on imperfectly drained tills with seepage, and the humid balsam fir – moss type on imperfectly drained tills. A third group, with low seedling densities (< 15 000 seedlings/ha), included three phases recognized by their important herb cover associated with a less abundant moss cover: the dry balsam fir – herb type on well drained till, the mesic balsam fir – white birch – herb type on moderately well drained till, and the mesic rich balsam fir – herb type on moderately well drained tills with seepage. Low densities of fir advanced regeneration seemed to be related to the abundance of leaf litter on the forest floor that could hinder fir regeneration. Insufficient natural coniferous regeneration can be anticipated in this last group if harvesting follows the 45-year rotation currently used now in Quebec.
Spatial analysis of ponderosa pine trees infected with dwarf mistletoe
Authors: Reich Robin M. , Mielke Jr. Paul W. , Hawksworth Frank G.
Published: July 2007

Distance-based multiresponse permutation procedures are presented as an alternative method of characterizing the spatial point pattern of mapped data sets. Methods are described for studying the spatial relationships and patterns in populations consisting of two or more groups. The ability of multiresponse permutation procedures to detect both nonrandom spatial patterns and segregation is compared with Hopkins and Skellam's coefficient of aggregation and Pielou's index of segregation, respectively, using data on the size and severity of dwarf mistletoe (Arceuthobiumvaginatum ssp. cryptopodum (Engelm.) Hawksw. & Wiens) infection of ponderosa pine (Pinusponderosa Laws.) trees. One advantage of multiresponse permutation procedures is that it uses all of the data in the analysis instead of a random sample that is subject to edge effect and sampling errors. Unlike distance sampling, multiresponse permutation procedures are not linked to specific model assumption and hence are more widely applicable as a descriptive measure. However, this method is computationally intensive and has certain limitations, which are highlighted in the discussion.
No variation is detected in the chloroplast genome of Pinustorreyana
Authors: Waters Elizabeth R. , Schaal Barbara A.
Published: July 2007

Pinustorreyana Parry ex Carrière has only two extant populations, containing less than 10 000 individuals in total. The two populations are in California, in San Diego County and on the island Santa Rosa. They are separated by 280 km and have been isolated for more than 8000 years. Random genetic drift over this period of time should have resulted in genetic differentiation between the two populations. We surveyed the chloroplast DNA of 24 individuals of P. torreyana for both restriction site and length polymorphisms with 26 restriction enzymes. The San Diego and Santa Rosa populations were monomorphic at over 150 restriction sites. Moreover, there was no detectable length variation. The results of this study suggest that P. torreyana has been monomorphic at these sites since before the two populations were isolated.
Optimal management of loblolly pine plantations with stochastic price trends
Authors: Haight Robert G.
Published: July 2007

An economic analysis of loblolly pine (Pinustaeda L.) plantation management options with stochastic sawtimber and pulpwood stumpage price trends is conducted using the North Carolina State University Plantation Management Simulator, a widely used model in the southeastern United States. Results for stands with a range of site indices suggest that regimes with high planting densities combined with commercial thinning options have higher expected present values than do regimes without thinning options, especially in plantations with hardwood competition. Such regimes are superior because high planting densities increase the returns from pulpwood thinnings without compromising sawtimber volume at rotation age. Further, high planting densities maintain the option to produce either sawtimber or pulpwood depending on the stumpage prices at midrotation. Optimal regimes are conditional on the sawtimber and pulpwood prices at the time of planting. A comparison of results for plantations with and without hardwood competition suggests that when the hardwood stumpage price is likely to increase over time, removing hardwoods with commercial thinning is superior to removing hardwoods immediately after planting. Finally, planting and thinning regimes that are optimal for deterministic price trends provide near-optimal expected returns when employed in an environment where price trends are stochastic.
Area-based harvest scheduling and allocation of forest land using methods for multiple-criteria decision making
Authors: Howard Andrew F. , Nelson John D.
Published: July 2007

A new, deterministic methodology for simultaneous solution of the scheduling and allocation problems based on methods developed for multiple-criteria decision making is proposed. Seven steps for the use of multiple-criteria decision making techniques are reviewed, and the details of the proposed application to area-based harvest scheduling and forest land allocation are presented. The approach was used in a sample, hypothetical problem in which harvest schedules and allocations were developed for three competitors, using three decision criteria and two sets of criteria weights. The results indicate that the new method provides an effective alternative to traditional methods and offers numerous advantages including the explicit consideration of multiple objectives.
Foliar responses of tamarack and black spruce to drainage and fertilization of a minerotrophic peatland
Authors: Mugasha Ancelm G. , Pluth Donald J. , Hillman Graham R.
Published: July 2007

A drainage and fertilization experiment was established in 1989 in a tamarack (Larixlaricina (Du Roi) K. Koch) and black spruce (Piceamariana (Mill.) B.S.P.) mixed natural stand growing on a minerotrophic peatland. The drained site was ditched in fall 1987. Fertilization treatments of N–P–K at 0:0:0, 0:80:120, 200:80:120, and 400:80:120 kg•ha−1 (N as urea) were applied in late May 1989 Tamarack short-shoot needles and black spruce current-year needles, sampled on 31 August 1989 and 2 September 1990, were analysed for unit needle mass and N, P, and K. Drainage without fertilization increased foliar N, P, and K concentration of tamarack and black spruce, with larger responses occurring in tamarack. However, drainage decreased needle mass of unfertilized black spruce, although net assimilation rate increased, suggesting that an increased proportion of photosynthate was allocated to root development. Needle mass of tamarack was not affected in 1989 but was increased in 1990 by drainage, indicating different acclimation mechanisms to drainage by the two species. Responses in unit needle mass and foliar N and P concentration of both species to P–K alone, and (or) N–P–K fertilization, were higher on the drained than on the undrained site. Increased availability and uptake of N and P with a lowered water table were a likely consequence of increased near-surface soil temperature, improved soil water–soil aeration relations, and accelerated N and P mineralization and uptake rates. Foliar N, P, and K of tamarack were more responsive to fertilization than those of black spruce. N–P–K elevated foliar N concentrations of tamarack and black spruce and resulted in concomitant increases in needle mass, suggesting that N was limiting both species. Addition of P–K alone increased foliar P concentration and foliar mass of tamarack, indicating a P limitation to tamarack growth.