bluuebunny/crossref_metadata_2025 huggingface dataset:
Sulfate retention and cation leaching of forest soils in response to acid additions
Authors: Fasth William J. , David Mark B. , Vance George F.
Published: July 2007

A vacuum extractor was used to examine the effects of increased SO42− deposition on net S retention and cation leaching in three Maine Spodosols (Berkshire, Dixfield, and Rawsonville series) and an Illinois Alfisol. Columns (leached daily for 30 days with either a simulated throughfall solution containing 80 μequiv. SO42−•L−1 (pH = 4.77) or a simulated throughfall solution plus 200 μequiv. H2SO4•L−1 (pH = 3.66)) were constructed using O horizons over upper B (Bh or Bhs) and lower B (Bhs or BC) horizons for the Spodosols and two depth increments of bulked soil (0–12 and 12–25 cm) for the Alfisol. Leachate concentrations of base cations were dominated by Ca2+ and were generally greater in the Alfisol than in the Spodosol leachates. Declining concentrations of base cations and NH4+ with time led to an increase in Al3+ concentrations and a decrease in pH for some of the Spodosol leachates (e.g., leachate Al3+ increased from 19 μequiv. Al3+ •L−1 (day 2) to 194 μtequiv. Al3+ •L−1 (day 30), and pH decreased from 5.53 to 4.41, respectively, for the Dixfield high-S treatment). Columns that received the high-S treatment retained a greater percentage of the added S than those that received the low-S treatment because of increased SO42− adsorption in the former. High rates of net organic S mineralization were found for all soil types (e.g., 169 μg organic S•g−1 over 30 days for the Rawsonville Bhl horizon, 15% of the total S); no treatment effects were found for the amount of S mineralized. Trends in net S retention across soil type (within the same treatment) reflected increases in soil SO42− from adsorption, as well as decreases in organic S from mineralization. When net S mineralization was removed from leaching losses of S, trends in net S retention closely reflected SO42− adsorption differences (50, 23, 8, and 1% of the added S retained by the Rawsonville, Dixfield, and Berkshire series, and the Alfisol, respectively, for the high-S treatment). Because of the low SO42− adsorption capacity of the Alfisol relative to the Spodosols, organic processes were more important in affecting net S retention for the Alfisol. Inorganic processes of S retention were more important for the three Spodosols studied.
Modulus of elasticity and tensile strength of Douglas-fir roots
Authors: Commandeur Paul R. , Pyles Marvin R.
Published: July 2007

The modulus of elasticity and the tensile strength were determined for a sample of live Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) roots collected in the Oregon Coast Range. Most of the roots displayed both a "form" modulus of elasticity and a "material" modulus of elasticity. The form modulus occurred as a tortuous root straightened out, whereas the material modulus developed following this initial straightening as the wood fibers within the root directly resisted elongation. The average form and material moduli of elasticity were, respectively, 185 and 503 MPa, whereas the average tensile strength was 17 MPa.
Historical analysis of changes in land use and carbon stock of vegetation in south and southeast Asia
Authors: Flint Elizabeth P. , Richards John F.
Published: July 2007

A time series (1880, 1920, 1950, 1980) of estimates of land use and carbon content of vegetation is presented for a contiguous area of 1.7 × 106 km2 in northern India, Bangladesh, and Burma. This was developed using sequential bookkeeping models, which systematically incorporate official agricultural and forest statistics with ecological, botanical, historical, geographical, and demographic data. For 149 administrative units, aggregated into 39 ecological zones, we estimated area and carbon content for each of the following land-use categories: net cultivated area, settled–built-up area, forest–woodland, interrupted woods, grass–shrub complexes, barren – sparsely vegetated areas, wetlands, and surface water. Dominant patterns of land-use change were deforestation, agricultural expansion, and wetland clearance, but significant regional and temporal disparities were observed. For the entire study region, the estimated standing stock of carbon in biomass declined by 2.62 Gt over the century. Release by periods was 911 Mt for 1880–1920, 750 Mt for 1920–1950, and 964 Mt for 1950–1980. Forest–woodland and interrupted woods vegetation released carbon equivalent to over 90% of the total release. Both conversion of forest to other vegetation types and reduction over time of biomass within vegetation types contributed significantly to decreases in total standing carbon stock during the period.
Foliar responses of black spruce to thinning and fertilization on a drained shallow peat
Authors: Mugasha Ancelm G. , Pluth Donald J. , Higginbotham Kenneth O. , Takyi Sam K.
Published: July 2007

A thinning and fertilization experiment was established in 1987 in a 50- to 60-year-old black spruce (Piceamariana (Mill.) B.S.P.) stand growing on a shallow, boreal (central Alberta), minerotrophic peatland drained in 1986. The experiment was a split-split plot design with thinning as the main factor, fertilization as the subfactor, and distance from drainage ditch as the subsubfactor. Current and 1-year-old foliage, collected during late August 1988, was analysed for mass and N, P, and K. Black spruce responded to thinning, fertilization, and distance from a drainage ditch. Thinning alone increased foliar N and P concentration and unit needle mass by 12, 30, and 16%, and foliar N and P content by 30 and 41%, respectively. The relative increases in foliar mass and N concentration and content of current needles in N, NP, or NPK treated plots were generally higher in unthinned subplots and distant subsubplots than in thinned subplots and proximate subsubplots, suggesting that N was more limiting in unthinned plots and distant subsubplots. Although the addition of P and K alone or in combination elevated foliar P and K concentrations and contents, there were no concomitant significant changes in unit needle mass, suggesting that P and K were not limiting.
Influence of dormancy induction treatments on western hemlock seedlings. II. Physiological and morphological response during the first growing season on a reforestation site
Authors: Grossnickle S. C. , Arnott J. T. , Major J. E.
Published: July 2007

Western hemlock (Tsugaheterophylla (Raf.) Sarg.) seedlings from four dormancy induction treatments (DIT) (i.e., long-day dry, long-day wet, short-day dry, short-day wet) were planted on a coastal reforestation site in British Columbia and monitored for physiological response and morphological development over the first growing season. Seedlings in all DIT showed a similar net photosynthetic, needle conductance, and shoot water potential response to seasonal low temperature, non droughty, and late summer drought conditions. Pressure–volume analysis at the beginning of the growing season (late February) showed short-day wet seedlings to have lower saturated and turgor loss point osmotic potentials than other DIT, while at the end of the growing season (October) there was no osmotic potential difference between DIT. At the end of the growing season, short-day wet seedlings had a much lower maximum modulus of elasticity than other DIT, indicating their shoots were still elongating. Morphological assessment 1 month after field planting showed short-day DIT seedlings had less needle damage and greater root development in response to continuous low temperature exposure. Four months after planting, long-day wet seedlings had the greatest shoot (i.e., height, root collar diameter) and root development in response to mild temperatures and high soil moisture conditions. Eight months after planting, survival was between 95 and 97% for all DIT. Long-day DIT seedlings had the greatest height and all DIT had similar root collar diameter and root development. Short-day DIT seedlings had the best shoot/soil roots ratio. Short-day wet seedlings had the least number of stem units per centimetre of new shoot development throughout the growing season. Results are discussed in reference to stock quality assessment presented in the first paper of this series.
Autumnal allocation of phosphorus in black alder, eastern Cottonwood, and white basswood
Authors: Côté Benoît , Dawson Jeffrey O.
Published: July 2007

Changes in leaf and current year bark phosphorus (P) concentrations of actinorhizal black alder (Alnusglutinosa (L.) Gaertn.), eastern cottonwood (Populusdeltoides Bartr. ex. Marsh.), and white basswood (Tiliaheterophylla Vent.) were determined during autumn on a mine-spoil site and a contrasting prairie site. During the last 2 weeks of sampling (4 weeks for alder at the prairie site), leaf P concentrations decreased by 43% for black alder and 23% for eastern cottonwood at the mine-spoil site and by 30% for black alder and 26% for white basswood at the prairie site. Concurrent increases in bark P concentration were observed only for eastern cottonwood and white basswood. Changes in leaf, bark, and root P of potted black alder seedlings were also followed in a parallel experiment. Bud set was associated with the onset of increasing leaf P concentration and content and stabilizing bark P content, while roots continued to accumulate P. The ratio of bark P content to root P content as well as the ratio of bark dry weight to root dry weight increased during the last stages of leaf senescence. Our results suggest that black alder can resorb a large proportion of its leaf P during leaf senescence, particularly when P availability is low. Both twigs and roots served as storage tissues for P, with roots acting as a primary sink in early autumn and bark acting as a sink for subsequently resorbed leaf P.
Preliminary evaluation of genetic variation of weevil resistance in interior spruce in British Columbia
Authors: Kiss G. K. , Yanchuk A. D.
Published: July 2007

White pine weevil (Pissodesstrobi (Peck)) damage in three interior spruce open-pollinated progeny tests in north central British Columbia was evaluated to examine the patterns of attack among families. While the overall incidence of damage was different across sites (i.e., Quesnel 9%, Red Rock 37%, and Aleza Lake 63%), correlations on a family-mean basis (percentage attacked per family) at Red Rock and Quesnel as well as Red Rock and Aleza Lake were significant (r = 0.63 and 0.71, respectively). Estimates of family heritability across sites for damage was high (hf = 0.77 ± 0.11), but individual heritability was only moderate (hi = 0.18 ± 0.03). More vigorous families, as determined by 10-year family mean height superiority prior to weevil attack, were damaged less frequently than those with average and poorer performance. Negative correlations of mean family height at 10 years of age with incidence of damage (on a family-mean basis) and mean family diameter with incidence of damage were significant (r = −0.51 and −0.44, respectively). These data suggest that there is a moderate genetic basis for resistance to weevil attack in interior spruce and that selection for height and diameter growth may improve resistance to weevil attack.
Winter desiccation and solar radiation in relation to red spruce decline in the northern Appalachians
Authors: Hadley Julian L. , Friedland Andrew J. , Herrick Graham T. , Amundson Robert G.
Published: July 2007

Exposure to direct solar radiation was correlated with needle death within individual high-elevation red spruce (Picearubens Sarg.) shoots following winter injury episodes at six sites in 1980 and 1989. We observed extensive visible needle damage to red spruce in northern New England between March and May of 1989 and determined that it was preceded by desiccation. In an independent growth chamber experiment, red spruce needles were heated to above freezing when exposed to strong illumination in calm subfreezing air. Rapid needle cooling occurred when the radiation load was suddenly reduced at the end of each light period, and needles desiccated severely within 10 days. These separate observations are consistent with three hypotheses: injury results from (i) desiccation, (ii) rapid needle cooling, (iii) freezing injury caused by a reduction in cold hardiness due to solar heating. These three mechanisms are not necessarily mutually exclusive.
The influence of reproductive traits on the capture of genetic gain
Authors: Haines Russell J. , Woolaston Robert R.
Published: July 2007

The effect of unavoidable selection for reproductive traits, when deriving the production population from the breeding population, is considered in terms of genetic gain in economic traits. The resultant reduction in genetic gain is likely to be sufficient to constitute a major obstacle to the use of a particular propagation strategy only when (i) the proportion of genotypes that can be propagated is very low; (ii) the proportion of genotypes to be retained for the production population is relatively high and the proportion that can be propagated is low; (iii) strong adverse correlations between economic and reproductive traits coincide with a high retained proportion and (or) a low propagation rate.
The Canadian lumber industry and the macroeconomy: a vector autoregression analysis
Authors: Jennings Sarah , Adamowicz Wiktor , Constantino Luis
Published: July 2007

The nature of the relationships between the Canadian lumber industry and the macroeconomy are investigated by estimating a 10-variable, three-lag vector autoregressive model for the period 1968 to 1987. We find that housing-start activity in North America has a prolonged and significant effect on the level of Canadian lumber production, exports, and prices. However, our results do not support the existence of strong exchange and interest-rate effects in the lumber sector. The use of general equilibrium specifications in forest sector modeling is suggested by the analysis. We explore the robustness of our results to alternate model specification and estimation procedures and identify problems that merit further investigation.
Retrospective shoot growth analysis for three seed sources of loblolly pine
Authors: Harrington Constance A.
Published: July 2007

Height growth by year and by individual cycle on the terminal shoot was reconstructed from stem analysis for 45 loblolly pine (Pinustaeda L.) trees that were 35 years old. Sample trees represented three seed sources (Clark County, AR; Livingston Parish, LA; and Onslow County, NC), each of which had been planted at three installations (Arkadelphia, AR; Poplarville, MS; and New Bern, NC) located in the general geographic area where one of the seed sources had been collected. Stem analysis was facilitated by the development of a staining technique that enhanced recognition of the boundaries between individual height-growth cycles and between years. Both annual height growth and number of cycles produced varied with tree age, seed source, and installation. Number of cycles produced per year ranged from two to seven; maximum annual production of cycles per seed source was achieved between ages 3 and 10 years. Even between ages 30 and 35, trees still exhibited polycyclic behavior, producing two to five cycles annually. Annual height growth was greatest between ages 4 and 15; height growth declined with age more rapidly than annual number of cycles. The relationship at each installation between cumulative height and cumulative number of cycles showed that the tallest seed source (Onslow in all cases) was the one that had produced the greatest number of cycles. Shorter trees at the poorest site resulted from lower numbers of cycles produced and, particularly after the production of 50 to 65 cycles, shorter mean cycle length. For all three seed sources, mean height was greatest at the installation where the trees produced the most cycles. Height-growth curves for two of the installations crossed, demonstrating differences in height-growth patterns related to site characteristics.
Growth and morphology of western red cedar seedlings as affected by photoperiod and moisture stress
Authors: Krasowski M. J. , Owens J. N.
Published: July 2007

One-year-old container-grown seedlings of western red cedar (Thujaplicata Donn) were subjected to short days (8 h) and moisture stress, applied separately and in combination, and compared with untreated seedlings. The treatments were applied at various times during the growing season and lasted 2 and 4 weeks. Short days slowed height growth only when applied during the most rapid period of shoot elongation in late June and early July. Short days combined with moisture stress always reduced the final height regardless of the time and duration of applied treatments. Moderate moisture stress applied alone in mid-August hastened root dry weight gain but did not affect other morphological characters. The applied treatments had no lasting effects upon mitotic activity of terminal shoot apices and resulted in no differences in the timing of fall cessation of mitotic activity. The study describes details of the 1st-year growth of containerized western red cedar seedlings that were not subjected to the above specified treatments. It reports on growth rates for several morphological characters, such as height, number of stem units, root collar diameter, and shoot and root dry weights. Also, apical transitions in leaf initiation, stomatal distribution on leaf and cotyledon surfaces, and leaf wax features are described.
Superior growth potential in trees: What is its basis, and can it be tested for at an early age?
Authors: Pharis R. P. , Yeh F. C. , Dancik Bruce P.
Published: July 2007

Inherently rapid growth in black spruce (Piceamariana (Mill.) B.S.P.) and radiata pine (Pinusradiata D. Don) could be characterised at a relatively early age (e.g., 3–6 months from germination) by growing progeny of family crosses in near-optimal phytotron or glasshouse environmental conditions. This observation was retrospective in nature, in that the studies of very early performance utilized stored seed from families that had been already tested to age 10+ years in field progeny trials. The very early traits that show the most significant family correlation with the field performance (height or stem volume) are total height, height growth, stem volume, or stem dry weight. The possibility that inherently rapid growth in trees may be causally related to concentration of endogenous plant hormones of the gibberellin class is discussed in relation to the recent finding (S.B. Rood, R.I. Buzzell, L.N. Mander, D. Pearce, and R.P. Pharis. 1988. Science (Washington, D.C.), 241: 1216–1218.) that heterotic growth (hybrid vigour) in maize was strongly related to the concentration of gibberellin A1 (a shoot growth effector in maize) and gibberellin A19 (a precursor to gibberellin A1). Preliminary evidence, based on analysis of hybrid and parental poplar tissue, and on the positive and significant growth response of black spruce slow-growing families (but not fast-growing families) to applied gibberellin (A4/7 mixture), supports the possibility that rapid-growing conifer families may have near-optimal (high) concentrations of endogenous gibberellins, and conversely, that some slow-growing families, at least, may have lower endogenous gibberellin concentrations.
Major gene resistance of Scots pine to western gall rust
Authors: Kamp Bart J. van der
Published: July 2007

Grafted ramets, full-sib families, and open-pollinated families were derived from two healthy and one western gall rust (Endocronartiumharknessii (J. P. Moore) Y. Hiratsuka) infected Scots pine (Pinussylvestris L.) and inoculated with western gall rust. Resistance appeared to be a qualitative character; grafts and seedlings either had many infected shoots or none. All F1 families for which the diseased tree was one of the parents were about 50% infected. All other full-sib families showed <15% infection. There was no distinction between bulk inoculum collections from Scots and from lodgepole (Pinuscontorta Dougl.) pine. It is proposed that susceptibility to western isolates of the gall rust in the Scots pine trees tested in this experiment is conditioned by a dominant gene.
Invitro propagation of Fraser fir from embryonic explants
Authors: Saravitz Carole H. , Blazich Frank A. , Amerson Henry V.
Published: July 2007

Cotyledons, hypocotyls, and cotyledon–hypocotyl explants were excised from seeds of Fraser fir (Abiesfraseri (Pursh) Poir.) subjected to H2O2 treatment for 3, 6, 9, or 12 days and cultured on media containing 0–30 mg/L N-(phenylmethyl)-1H-purine-6-amine. Adventitious buds developed on hypocotyls and hypocotyls of cotyledon–hypocotyl explants, but rarely on cotyledons. Excised hypocotyls produced more buds than hypocotyls of cotyledon–hypocotyl expiants (1.6 vs. 1.1). Hypocotyls excised from seeds treated with H2O2 for 6 or 9 days and placed on medium containing 10 mg/L N-(phenylmethyl)-1H-purine-6-amine yielded the greatest number of buds, with a mean of three buds per hypocotyl. Elongated adventitious shoots were placed on media containing 0–40 mg/L 1H-indole-3-butyric acid to induce rooting. Forty-eight percent of shoots treated with 40 mg/L 1H-indole-3-butyric acid rooted, and the greatest number of roots per rooted shoot (3.0) was also noted at this concentration. Plantlets were transferred to a growing medium, but acclimation was unsuccessful
Retransformation bias in a stem profile model
Authors: Czaplewski Raymond L. , Bruce David
Published: July 2007

not available
A comparison of seasonal patterns of photosynthate production and use in branches of red spruce saplings at two elevations
Authors: Andersen Christian P. , McLaughlin Samuel B. , Roy W. Kelly
Published: July 2007

Seasonal patterns of carbon transport from 14C-labeled foliage were examined in red spruce (Picearubens Sarg.) branches at 1935 and 1720 m elevations in the Great Smoky Mountains National Park to characterize possible physiological mechanisms underlying the observed reductions in growth at high elevations. Current and 1-year-old foliage was labeled on 5- to 7-year-old branches of sapling-sized trees in June, August, and October. Retention of 14C was measured after 24 h, and allocation to other branch segments was characterized after 7 days. Total 14C-labeled carbon assimilation was greater in current than in 1-year-old foliage throughout the growing season. This suggests that photosynthetic capacity is high in developing foliage prior to needle maturity and remains high during the first growing season. In August, 14C retention in labeled foliage was less at the higher than at the lower elevation site, possibly reflecting increased respiratory losses that had been previously reported at the higher site. Retention of 14C in current-year shoots as a percent of 14C remaining after 7 days, a measure of sink strength, was high at both sites in June and remained high throughout the season in current-year shoots at the higher elevation site. The relatively high sink activity coupled with the large apportionment of biomass to current-year shoots (19.9 and 26.7% of total branch biomass at the lower and higher elevation sites, respectively) may make red spruce particularly susceptible to stresses such as winter injury that affect young foliage. In addition, the relatively greater sink activity of current-year shoots at the higher elevation site in August and October suggests that the contribution of current-year foliage to overall tree growth may be less at the higher than at the lower elevation site.
Steady-state nutrient preconditioning and early outplanting performance of containerized black spruce seedlings
Authors: Timmer V. R. , Armstrong G. , Miller B. D.
Published: July 2007

Conventional fertilization of black spruce (Piceamariana (Mill.) B.S.P.) container stock usually does not conform to steady-state nutrient conditions and may limit subsequent outplanting performance. Steady-state nutrient preconditioning of seedlings, characterized by maintaining stable tissue nutrient (N, P, and K) concentrations during the exponential growth phase, was induced by an exponentially based fertilization regime that compensated for low nutrient reserves in germinating seeds. By the end of the greenhouse rotation, this regime reduced the shoot/root ratio of the trees, but fell short of increasing seedling growth and nutrient status when compared with seedlings conventionally fertilized with equivalent amounts of nutrients. However, first-season height growth and shoot biomass of trees outplanted on different surface soils in pot bioassays were significantly improved by steady-state nutrient preconditioning and were accompanied by increased plant nutrient uptake, particularly N at the half-dose level and P at the full-dose level. Out-planting performance was higher on an upland site type, although relative response was greater on nutrient-poorer, lowland substrates. The preconditioning response from exponentially based fertilization was attributed to lower shoot/root mass ratio and more effective nutritional adaptation of the seedlings to the field environment. Under steady-state nutrient culture, seedling nutrient uptake conforms more closely with stable nutrient supply in nature, since expanding root systems exploit new soil volumes exponentially. Field performance of exponentially fertilized seedlings may be further enhanced when combined with balanced nutrient loading in the greenhouse phase.
The influence of cut-block size and adjacency rules on harvest levels and road networks
Authors: Nelson J. D. , Finn S. T.
Published: July 2007

Harvest levels and road construction and maintenance schedules are reported for combinations of cut-block size and exclusion-period length. Exclusion-period length had a greater effect than block size on harvest and road schedules. Harvests constrained by 20- and 30-year exclusion periods were, respectively, an average of 15 and 30% below the progressive clear-cutting solution. A combination of small openings and long exclusion periods led to significant reductions in harvests (43%) and caused a high percentage of the road network to be constructed in the early decades. These long-term, spatially constrained forest plans were formulated as integer programs and solved with a random search algorithm.
Symptom expression among half-sib slash pine progenies after inoculation with Cronartiumquercuum f.sp. fusiforme
Authors: Kuhlman E. George , Powers Jr. H. R.
Published: July 2007

Half-sib progeny from 106 slash pine (Pinuselliottii Engelm. var. elliottii) trees in a rust-resistant orchard were inoculated with fusiform rust (Cronartiumquercuum (Berk.) Miyabe ex Shirai f.sp. fusiforme) using the concentrated basidiospore spray system. Mass susceptible seedlings served as the control in each of the five inoculations needed to screen the 106 families. Relative susceptibility compared with the control was determined by the percentage of seedlings with galls 6 or 9 months after inoculation. According to the 0.70 disease ratio computation (percentage with galls in the test family ÷ percentage with galls in the susceptible control ≤ 0.70), 59 of the 106 families were resistant. The 0.70 disease ratio was more conservative at designating families as resistant than Fisher's least significant difference test (67 of 106 resistant), but was more liberal than Tukey's honestly significantly different test (42 of 106 resistant). Other symptoms of infection were recorded to determine frequency of occurrence. Multiple symptoms occurred on many seedlings; however, the symptom indicating the greatest susceptibility was used in the analysis. Galls, stem symptoms without any swelling, needle spots, and no symptoms were taken to indicate progressively decreasing susceptibility to fusiform rust. The largest variation among resistant families occurred in the frequency of symptomless seedlings (0–77% frequency among families in the five inoculations). The results from this study indicate that the frequencies of different symptom types observed following inoculation might be utilized to separate various types of resistance within a group of pine families characterized as resistant.
Effects of simulated acid rain on needle wettability and rain retention by two Sitka spruce (Piceasitchensis) clones
Authors: Percy K. E. , Baker E. A.
Published: July 2007

The effect of simulated rain acidity (pH 2.6, 3.4, 4.2, and 5.6) on wettability and rain retention was investigated for elongating needles on stecklings of two Sitka spruce (Piceasitchensis) (Bong.) Carr) clones over an 11-week period. There were highly significant differences in contact angle between pH treatments, clones, and sample dates. Contact angles on needles of both clones exposed at pH ≤ 4.2 were significantly smaller than those on needles exposed at pH 5.6. Needles from both clones exposed to simulated rain at pH ≤ 4.2 retained significantly more simulated rain containing sodium fluorescein. These changes to needle surface properties following realistic exposure to simulated acid rain could have important consequences for processes occurring at the phylloplane, such as ion exchange.
Geographic patterns of variation in allozymes and height growth in white spruce
Authors: Furnier Glenn R. , Stine Michael , Mohn Carl A. , Clyde Merlise A.
Published: July 2007

Variation in height at ages 9 and 19 years and at six polymorphic allozyme loci was examined for 22 seed sources (populations) in a range-wide white spruce (Piceaglauca (Moench) Voss) provenance test planted in Minnesota. There were strong differences among populations for height, with 48.0 and 54.1 % of the genetic variation for height at ages 9 and 19, respectively, due to differences among populations. Mean observed and expected estimates of allozyme heterozygosity were 0.306 and 0.290, respectively, with little deviation from genotype frequencies expected under a Hardy–Weinberg equilibrium. In contrast with the height data, an average of only 3.8% of this variation was due to differences among populations. Geographic trends were apparent in the height data, with northern and western sources performing the poorest. Neither univariate nor multivariate analyses revealed any geographic trends in the allozyme data. The very different distributions for height and allozyme variation suggest that evolutionary forces are acting in different ways on the genes controlling these traits, and that allozyme data will have limited value in developing sampling strategies for gene conservation programs, where the preservation of germ plasm adapted to many sites throughout a species range is important.
Mechanical devices for extracting stuck increment borers
Authors: Yamaguchi David K.
Published: July 2007

A hoist–puller (come-along) or a scissor jack can be used to extract stuck increment borers from trees. An electric drill is also helpful for removing jammed wood from the inside of borers.
Effects of irrigation and fertilization on the ground vegetation in a 130-year-old stand of Scots pine
Authors: Kellner Olle , Mårshagen Mickael
Published: July 2007

Seven years of irrigation and liquid fertilization brought about drastic changes in the vegetation of the field layer (vascular plants) and bottom layer (lichens and mosses) in a mature pine–heath community. Forty new vascular plant species became established. The five most abundant new species had abundant seed sources in the vicinity of the experimental area and were species with effective seed dispersal and (or) a persistent seed bank. Many of the new species, however, dispersed long distances to colonize the experimental area. Wind was the dominant dispersal mechanism among the species that established early, whereas most of the species that established during the later part of the study period had no obvious adaptation for wind or animal dispersal. Two new species with rapid vegetative spread and tall stature, Rubusidaeus L. and Epilobiumangustifolium L., dominated the field layer at the end of the study period. Of the original field layer species, Callunavulgaris (L.) Hull decreased, while the other two dwarf shrubs, Vacciniummyrtillus L. and Vacciniumvitis-idaea L., remained largely constant. The bottom layer as a whole decreased. All reindeer lichens (Cladina spp.) disappeared, and the dominant moss, Pleuroziumschreberi (Brid.) Mitt., decreased markedly. Some new litter-growing moss species became established.
Biogeochemical interactions between acidic deposition and a low-elevation spruce–fir stand in Howland, Maine
Authors: Lawrence Gregory B. , Fernandez Ivan J.
Published: July 2007

The biogeochemical interactions between acidic deposition and a forest ecosystem were investigated in a low-elevation spruce–fir stand in east-central Maine. A 0.2-ha plot was intensively instrumented for measurement of precipitation, throughfall, and soil solutions. Annual precipitation for 1989 had an average pH of 4.39 and an estimated 424, 191, and 231 mol•ha−1 deposition of H+, SO42−, and NO3−, respectively. Soil water flux was determined from precipitation and evaporation estimates. Ion flux data are presented for the 12-month period of 1989. Approximately 50% of inorganic strong acid acidity in precipitation plus unmeasured dry deposition was neutralized by the canopy for the measurement period reported. Soil and soil solution buffering were largely controlled by organic matter and mineral weathering. Mobilization of inorganic Al was minimal (<3 μM) in both the Oa and Bs horizons. Ratios of Al/Ca2+ were well below values considered to cause inhibition of Ca2+ uptake. Annual deposition of SO42− in throughfall (285 mol•ha−1) approximated output (291 mol•ha−1). Virtually 100% of wet-only NO3− input and 90% of wet-only NH4+ input were retained within the ecosystem.
The effects of sewage sludge on growth and foliar and soil chemistry in pole-stage Corsican pine at Ringwood Forest, Dorset, UK
Authors: Moffat A. J. , Matthews R. W. , Hall J. E.
Published: July 2007

An experiment to examine the use of sewage sludge as a fertiliser for pole-stage Corsican pine (Pinusnigra var. maritima (Ait.) Melville) is described. Dominant and codominant trees responded markedly to additions of sludge at rates of 200 and 400 m3•ha−1, increasing sawlog volume by over 50% in treated plots. Foliar analyses suggest that the trees have responded to phosphorus in the sludge. The greatest impact of sludge on the soil occurred in the litter layer; concentrations of nitrogen, phosphorus, calcium, zinc, copper, cadmium, and lead were all greater compared with concentrations of untreated controls. Nevertheless, at rates of sludge application appropriate to fertilising (200 m3•ha−1), additions of heavy metals are considered small and are unlikely to cause adverse environmental effects.
Statistical error analysis for biomass density and leaf area index estimation
Authors: Woods Kerry D. , Feiveson A. H. , Botkin Daniel B.
Published: July 2007

Dimension analysis uses fitted allometric relationships to estimate whole-tree characteristics from dimensional measurements. Errors in dimension-analysis estimates of forest stand biomass and leaf area are often unreported and rarely analyzed. Errors may arise from measurement error, choice of model, fitting of parameters in models, and spatial variation within a sampled stand. Examination of these components separately will show how efficiency can be most effectively increased and balanced. We used dimension analysis to estimate biomass density and leaf area index for stands of trembling aspen (Populustremuloides Michx.) and black spruce (Piceamariana (Mill.) B.S.P.) in the Superior National Forest, Minnesota, United States. Estimates had average coefficients of variation ranging from 11% (aspen biomass density) to 23% (spruce leaf area index). Partitioning of these errors showed that error sources varied with species, variable, and site conditions, but most error was due either to parameter estimation or to spatial variation; model inaccuracies contributed only trivially to total error. The most cost-effective means of increasing precision of estimation would be to sacrifice more trees (even with less precise measurements of individual trees) to fit the models, or sample larger areas in stands; more sophisticated models would have little effect on error.
Forest detritus and cycling of nitrogen in a mountain lake
Authors: Wissmar Robert C.
Published: July 2007

Small lakes of forested watersheds can receive large subsidies of forest matter, but little is known about the material's role in the cycling of nutrients within these ecosystems. This paper examines the influence of detritus and dissolved nitrogen from a forest on the nitrogen cycle of a small subalpine lake in the Cascade Mountains of Washington during the ice-free period (98 days). Relationships between changing detrital microbial biomass, oxygen uptake rates, and water conditions indicate that dissolved inorganic nitrogen concentrations and water temperatures control the decomposition of the nitrogen-depleted detritus. The microbial respiration rates suggest the probable co-occurrence of several microbial oxidation and reduction reactions that could be cycling nitrogen in oxic–anoxic interfaces of detrital deposits, sediments, and riparian areas. Estimates of nitrogen gains and losses (3 and 7%, respectively) by forest detritus are low in comparison with total nitrogen uptake and releases within the lake during the study period (378 and 347 mg•m−2, respectively) and point to the need to examine other methods for measuring detrital nitrogen fluxes. The total nitrogen input to the lake (2600 mg•m−2 for the study period) from the watershed exceeds the lake output (2120 mg•m−2 for the study period). The low output of total nitrogen appears to be due to retention of dissolved inorganic nitrogen and particulate organic nitrogen within the lake. Most dissolved inorganic nitrogen retained is nitrate suggesting possible losses through denitrification. Dissolved organic nitrogen is the major proportion of the total nitrogen fluxes, but related mass balance errors indicate the need for further definition of both the sources and fates of dissolved organic nitrogen for the ecosystem.
The effect of root pruning on the maturation of loblolly pine (Pinustaeda) plantlets, rooted hypocotyls, and seedlings
Authors: Wisniewski L. A. , Brandon D. L. , McKeand S. E. , Amerson H. V.
Published: July 2007

Loblolly pine (Pinustaeda L.) tissue culture plantlets, seedlings, and rooted hypocotyls were subjected to three root-pruning treatments (control, half apices pruned, all apices pruned) to determine if pruning could alter the maturation state of the shoots, and if there was a correlative alteration of shoot cytokinin levels. Height, multiple characteristics of shoot morphology correlated with maturation, and root morphology were assessed. In comparisons with control plantlets, pruning significantly decreased plant height in half-pruned and all-pruned plantlets, needle length in all-pruned plantlets, terminal bud length and diameter in half-pruned and all-pruned plantlets, and needle dry weight in half-pruned plantlets. When these shoot morphological characteristics were regressed against height, the half-pruned plantlets appeared more juvenile than controls for both terminal bud length and diameter. All-pruned plantlets did not differ from controls. In comparisons of the three intact plant types, the plantlets were more mature than seedlings and rooted hypocotyls based on assessments of terminal bud length, terminal bud diameter, and needle length. However, in the half-pruned treatment these three characteristics did not differ among plantlets, seedlings, and hypocotyls, showing that they were equivalent for maturation status. Root pruning significantly increased the number of root apices for all plant types but did not increase plantlet or rooted hypocotyl cytokinin levels.
Enzyme gene markers as indicators of the initial ploidy in anther cultures of trees
Authors: Müller-Starck G. , Jörgensen J.
Published: July 2007

Enzyme gene markers proved effective as indicators of the initial ploidy of invitro material from anther cultures. The suggested methods were tested by using embryoids or calli of the tree species Aesculushippocastanum L., Fagussylvatica L., and Quercuspetraea (Mattuschka) Liebl. Three categories of problems were considered: one identified donor tree, a no longer existing donor tree, and donor trees of uncertain identity. Only haploids (dihaploids) were identified in F. sylvatica, haploids and a few diploids were identified in Q. petraea, and frequently occurring diploids were identified in A. hippocastanum. The results demonstrate the need to determine the initial ploidy of plantlets derived from anther cultures. Limitations in the case of chimeric tissues are outlined briefly.
Fractal dimensions of tree crowns in three loblolly pine plantations of coastal South Carolina
Authors: Zeide Boris , Gresham Charles A.
Published: July 2007

Because crown structure is closely associated with many aspects of tree growth, fractal dimension of the crown is likely to be a useful indicator of tree form as well as growth. This paper investigates the relationship between the fractal dimension of crowns and two growth-regulating factors, site quality and thinning intensity. The two-surface method allows one to calculate fractal dimension from the regression of foliage area (or mass) on the area (or volume) of the convex hull that envelopes the crown. The hull's volume can be computed from the length and width of a crown using an equation that accounts for the change in crown shape. Fractal dimensions of tree crowns were calculated for three loblolly pine (Pinustaeda L.) plantations of coastal South Carolina using detailed measurements of 72 dominant and intermediate trees. Analyses of data and the involved processes suggest that the fractal dimension of crown surface may change with site quality and thinning intensity.
Dendrochronological investigation of Larixlyallii at Larch Valley, Alberta
Authors: Colenutt M. E. , Luckman B. H.
Published: July 2007

Tree-ring chronologies have been developed for alpine larch (Larixlyallii Parl.), alpine fir (Abieslasiocarpa (Hook.) Nutt.), and Engelmann spruce (Piceaengelmannii Parry) for a tree-line site at Larch Valley in Banff National Park. The alpine larch and alpine fir chronologies are the first published chronologies developed for these species in the Canadian Cordillera. Alpine larch, a deciduous conifer, has many very narrow and missing rings, making chronology development difficult. These problems were resolved by identifying common marker rings among species growing at the same site. Chronologies for all three species show suppressed growth in the early to mid 1800s followed by a period of higher growth that peaked in the early to mid 20th century and has since declined. The exact timing and nature of response to favourable and unfavourable growth conditions vary with species. Alpine larch exhibits the highest sensitivity, lowest first-order autocorrelation, and greatest common variance, suggesting it has excellent potential as a source of proxy climate data for tree-line sites in this area. Preliminary correlations between Lake Louise climate data and larch ring-width and maximum latewood density chronologies show that there are significant correlations with summer temperature variables. Engelmann spruce and alpine fir growing at the same site show a similar response but are more strongly influenced by precipitation and growing conditions of the previous year.
Increased dark respiration and calcium deficiency of red spruce in relation to acidic deposition at high-elevation southern Appalachian Mountain sites
Authors: McLaughlin S. B. , Andersen C. P. , Hanson P. J. , Tjoelker M. G. , Roy W. K.
Published: July 2007

Rates of net photosynthesis and dark respiration of red spruce (Picearubens Sarg.) foliage were examined in relationship to soil and foliar nutrient status at three elevations across each of three mountains in the southern Appalachians. These studies tested our previously stated hypothesis that increased dark respiration and reduced growth were associated with natural or induced nutrient deficiency at higher elevation sites. A consistent and highly significant reduction in the ratio of net photosynthesis to dark respiration was found at the highest sites on each mountain compared with lower sites, as had been previously reported for the initial two test sites. This response was produced by significant increases in dark respiration that were associated with low foliar calcium levels and high foliar aluminum levels found at the higher elevation sites in this region. Net photosynthesis was generally comparable between sites. A consistently inverse relationship between dark respiration and foliar calcium was found across highest and lowest elevation sites, while the midelevation sites, where calcium:aluminum ratios were highest, showed less evidence of respiratory response to calcium. Calcium in shoots was significantly reduced in association with increasing levels of soil aluminum in the rooting zone across all sites. Collectively, these studies suggest that reduced calcium supply, occurring in association with competitive inhibition of calcium uptake by high concentrations of aluminum found in soil, may have reduced the availability of carbon for red spruce growth at higher elevation sites. Inferential evidence examined, including atmospheric deposition levels, soil solution chemistry, and historical tree-ring chemistry, suggests that acidic deposition would have been a contributing factor in inducing or amplifying calcium deficiency.
Snowfall interception on branches of three conifer species
Authors: Schmidt R. A. , Gluns David R.
Published: July 2007

Measuring the mass of snow on cut branch tips soon after snowfalls during two winters provided comparisons of catch by Engelmann spruce (Piceaengelmannii Parry), subalpine fir (Abieslasiocarpa (Hook.) Nutt.), and lodgepole pine (Pinuscontorta var. latifolia Engelm.). Analysis of these and other reported measurements confirmed (i) snow bridging by cohesion, (ii) bouncing of snow crystals by elastic rebound, and (iii) branch bending as mechanisms that determine the sigmoidal growth curves characterizing snow interception relative to snowfall. The fraction of snowfall intercepted by the branches was largest when storm accumulations were 3–4 mm water equivalent, with low specific gravity (0.04–0.07). Percent catch in snowfalls with 10 mm water and low specific gravity was near 50% for Engelmann spruce and about 45% for subalpine fir and lodgepole pine, but values decreased to near 30% in 20-mm storms. Catch was inversely proportional to the density of snow accumulations in the specific gravity range 0.04–0.13. Average branch catch was only about 10% of a storm with 10 mm water equivalent at 0.13 specific gravity. Meteorological conditions were more important than branch growth form in determining snow interception amounts on the conifers tested. The results suggest, as a hypothesis, a computational function for the fraction of snowfall caught on conifer crowns.
A modified production function analysis of changing southern forest productivity
Authors: Newman David H.
Published: July 2007

The analysis in this paper measures changes in forest productivity for 12 southern states using a modified, aggregate production function. The function combines cross section – time series, biological, and acreage data to estimate the shift in productivity, measured as either standing inventory plus removals or changes in inventory plus removals, over the past 4 decades. The annual shift in productivity is estimated to be approximately 0.5% for the standing volume measures used. However, productivity gains in the region have virtually stopped during the past decade. The largest contributions to productivity gains were from industrially owned lands and land managed as planted pine. Mixed pine–hardwood stands and public lands (except for plantations) showed lower productivity impacts. These results present an essential component for understanding the impact of technical change on aggregate forest productivity in the southern United States.