bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative and qualitative effects of a severe ice storm on an old-growth beech–maple forest
Authors: Takahashi Koichi , Arii Ken , Lechowicz Martin J. 
Published: July 2007

Comparing permanent plots censused in 1997 and again in 2005, we quantified the impact of a severe ice storm on forest composition and dynamics in an old-growth beech–maple forest in eastern Canada. Acer saccharum Marsh. and Fagus grandifolia Ehrh. accounted for 78% of stand basal area immediately before the January 1998 ice storm. By 2005, eight growing seasons after the ice storm, stand basal area had dropped from 49.1 m2/ha to 31.5 m2/ha, and total tree density (>1 cm diameter at breast height (DBH)) decreased from 6350 stems/ha to 3875 stems/ha. However, A. saccharum and F. grandifolia remained dominant, accounting for 74% of stand basal area. Detrended correspondence analysis of relative dominance ratios at each plot in 1997 and 2005 showed that community composition did not change much during this period for either understory (1 cm ≤ DBH < 10 cm) or canopy trees (DBH ≥ 10 cm). The ice storm did not lead to significant recruitment of saplings (DBH ≥ 1 cm), but appears to have only contributed more to the growth of already-established saplings. We conclude that the ice storm of 1998 substantially decreased stand basal area and stem density but did not act to change the overall species composition or tree diversity in this old-growth beech–maple forest.
Impact of simulated aspen shoot blight on trembling aspen
Authors: Blenis P.V. 
Published: July 2007

Although aspen shoot blight (ASB), caused by Pollaccia americana Ondrej, is a common disease of trembling aspen ( Populus tremuloides Michx.), its impact is uncertain. Mechanical wounding, previously shown to be a reliable surrogate for ASB infection, was used to assess ASB impact in two experiments. In the first experiment, the effect of date of wounding on impact was studied by wounding 1-year-old aspen on four dates between 29 June and 10 August 2001. Tree form at the end of the 2001 growing season varied with wounding date, and for each of the wounding dates, tree height was reduced relative to that of unwounded, control trees. After the 2005 growing season, only trees wounded on 17 July were shorter than unwounded trees and the difference in heights was only 62 cm. In the second experiment, trees spaced at 2.0 or 0.67 m were wounded in four successive seasons to determine the effect of multiple years of infection on trees growing at different densities. Simulated ASB reduced tree height by an average of 16 cm, whereas branchiness was not increased by ASB, even at the lower density. Although ASB should not be ignored, these results suggest that it is unlikely to be amongst the most destructive pests of intensively managed aspen.
Patterns of leaf area and growing space efficiency in young even-aged and multiaged coast redwood stands
Authors: Berrill John-Pascal , O’Hara Kevin L. 
Published: July 2007

Projected leaf area estimates were used to predict volume increment and basal area of second-growth coast redwood ( Sequoia sempervirens (D. Don) Endl.) trees on Jackson Demonstration State Forest, Mendocino County, California. Sample plots were established within even-aged and multiaged mixed-species stands. Redwood tree basal area growth was more strongly related to sapwood area than to tree size and differed significantly between canopy strata and overstory stratum crown classes. Projected leaf area was predicted from sapwood area for each tree, and summarized to the stand level, giving a maximum stand leaf area index (LAI) estimate of 14.9 m2/m2. Redwood tree growing space efficiency (GSE; the ratio of stem volume increment to leaf area) was greatest on average among emergent overstory trees, followed by dominant and codominant overstory trees. There was no evidence of declining overstory tree GSE with increasing leaf area over the range of data collected. A nonlinear model predicted increasing understory tree GSE with increasing leaf area. Models that predict basal area and LAI were developed to permit implementation of GSE models from basic inventory data.
Effect of tree, stand, and site variables on the allometry of Eucalyptus globulus tree biomass
Authors: António Nuno , Tomé Margarida , Tomé José , Soares Paula , Fontes Luís 
Published: July 2007

The objective of this study was to develop a system of compatible equations to estimate eucalyptus ( Eucalyptus globulus Labill.) tree aboveground biomass and biomass of tree components for forest biomass prediction across regional boundaries. Data came from 441 trees sampled on several sites (99 and 14 plots in planted and coppice regenerated stands, respectively) representative of the eucalyptus expansion area in Portugal. The system of equations, simultaneously fitted using seemingly unrelated regression, was based on the allometric model for the biomass of stem wood, stem bark, leaves, and branches. Total aboveground biomass was expressed as the sum of the biomass of the respective tree components. The study allowed the following conclusions: (i) there is a significant increase in the predictive ability of the models that include height (stem components) or crown length (crown components) as an additional predictor to diameter at 1.30 m; (ii) there is a clear effect of the stage of development of the stand on tree allometry, with a decreasing pattern of the allometric constants; (iii) no effect of stand density, site index or climate on tree allometry was found; and (iv) for practical purposes, the same system of equations can be used for planted and coppice regenerated stands.
Spread of beech bark disease in the eastern United States and its relationship to regional forest composition
Authors: Morin Randall S. , Liebhold Andrew M. , Tobin Patrick C. , Gottschalk Kurt W. , Luzader Eugene 
Published: July 2007

Beech bark disease (BBD) is an insect–fungus complex involving the beech scale insect ( Cryptococcus fagisuga Lind.) and one of two canker fungi. Beech scale was introduced to Halifax, Nova Scotia around 1890, presumably with the fungus Neonectria coccinea var. faginata Lohm. The disease has subsequently spread through a large portion of the range of beech. We used historical maps of the extent of the advancing BBD front (defined by presence of scale insects) in North America to estimate its rate of spread as 14.7 ± 0.9 km/year. This estimate did not account for stochastic “jumps” by the scale insects to several disjunct locations; therefore, this rate is a conservative estimate. Comparison of the year of scale colonization with beech density did not suggest a relationship between the scale spread rate and beech density. Our analyses also indicated that BBD has invaded less than 30% of regions where beech is present, but it has invaded most of the regions where beech is a dominant component of stands. Despite regional increases in beech mortality following invasion, considerable amounts of live beech remain in invaded areas. Moreover, the volume of beech has increased in most areas, though generally at lower rates than that observed for associated tree species.
Estimating branch production in trembling aspen, Douglas-fir, jack pine, black spruce, and balsam fir
Authors: Bernier P.Y. , Lavigne M.B. , Hogg E.H. , Trofymow J.A. 
Published: July 2007

Measuring net primary productivity of trees requires the measurement of total wood production of branches. Recent work on balsam fir ( Abies balsamea ) has shown that branch-wood production can be estimated as a function of foliage production. We extend the analysis to four other species found in the Canadian forest: black spruce ( Picea mariana ), jack pine ( Pinus banksiana ), Douglas-fir ( Pseudotsuga menziesii ), and trembling aspen ( Populus tremuloides ). Results show that the ratio of annual branch-wood production to annual foliage production is about 1.0 for conifer species (between 0.86 and 1.12) and 0.56 for aspen during a nondrought year. An analysis using field measurements of litterfall and stem-diameter increment from selected forested sites shows that branch-wood production accounts for a smaller proportion of aboveground net primary productivity in trembling aspen (15%–20%) than in conifer species (25%). Also, litterfall capture of small branches (<1 cm diameter) accounts for only 33% of branch detritus production in conifers and 50% in trembling aspen. This study supports the use of an alternative method for estimating branch-wood production that reduces the potential bias in field estimates of net primary productivity.
The demographic structure of European aspen (Populus tremula) populations in managed and old-growth boreal forests in eastern Finland
Authors: Latva-Karjanmaa Tarja , Penttilä Reijo , Siitonen Juha 
Published: July 2007

European aspen ( Populus tremula L.) is a keystone species for biodiversity in boreal forests. However, large aspen have largely been removed from managed forests, whereas regeneration and the long-term persistence of mature trees in protected areas are matters of concern. We recorded the numbers of mature (≥20 cm diameter) aspen in old-growth and managed forests in eastern Finland, based on a large-scale inventory (11 400 ha, 36 000 living and dead trees). In addition, saplings and small aspen trees were surveyed on thirty-six 1 ha sample plots. The average volumes of mature living and dead aspen were 4.0 and 1.3 m3/ha in continuous old-growth forests and 0.2 and 0.6 m3/ha in managed forests, respectively. These results indicate that large aspen trees in managed forests are a legacy of the past, when forest landscapes were less intensively managed. We conclude that the long-term persistence of aspen in protected areas can only be secured by means of restoration measures that create gaps large enough for regeneration to occur. More emphasis should be given to sparing aspen during thinning and to retaining mature aspen during regeneration cutting in managed forests.
Ecosystem carbon accumulation following fallow farmland afforestation with red pine in southern Quebec
Authors: Ouimet Rock , Tremblay Sylvie , Périé Catherine , Prégent Guy 
Published: July 2007

We assessed the organic C stocks and inferred their changes in vegetation biomass, forest floor, and soil using a 50 year chronosequence of red pine ( Pinus resinosa Ait.) plantations established on postagricultural fields in southern Quebec, Canada. The data come from soil and tree field surveys carried out in the 1970s in 348 sites. Organic C concentrations were usually measured in three major mineral soil horizons; for the remaining soil horizons, they were estimated using pedotransfer functions. The effect of soil order, drainage, and texture was analysed. Over 22 years, organic C accumulation rates (Mg C·ha–1·year–1) were 1.66 ± 0.03 in vegetation biomass, 0.56 ± 0.07 in forest floor, 0.86 ± 0.47 in loamy soils (0–100 cm), and –0.18 ± 0.24 in sandy soils (0–100 cm). The greater rate of C accumulation in loamy soils was due to the contribution of the 30–100 cm subsoil layer. The overall net accumulation of organic C in these plantation ecosystems was estimated to 51.4 ± 4.8 Mg C·ha–1at 22 years. Soils of these plantations acted as a C sink in the first two decades, particularly in loamy soils compared with sandy soils, with no major differences among soil order or drainage.
A hierarchical analysis of stand structure, composition, and burn patterns as indicators of stand age in an Engelmann spruce – subalpine fir forest
Authors: Gass Tobah M. , Robinson Andrew P. 
Published: July 2007

We studied the relationship between observed fire effects and stand age in a recently burned subalpine Engelmann spruce ( Picea engelmannii Parry ex. Engelm.) – subalpine fir ( Abies lasiocarpa (Hook.) Nutt.) forest in New Mexico. We installed a network of variable-radius plots to assess stand structure, and cored 379 trees to measure the spatial patterns of the stand ages with respect to fire boundaries. We found that pre-fire stand age and stand mortality were not significantly related at either of two spatial scales (p ≤ 0.33 and p ≤ 0.26). We also found that stand structure and stand composition were poor indicators of stand age. The random effects terms of a linear mixed-effects model revealed substantial heterogeneity in stand structure and composition with respect to age at fine spatial scales. Discussions of the factors contributing to stand-replacing fires in subalpine Engelmann spruce – subalpine fir forests might be improved by focusing on traits that are more reliably linked to fuel characteristics, rather than on the age of the stands.
Fuels on disturbed and undisturbed sites in the southern Appalachian Mountains, USA
Authors: Waldrop Thomas A. , Brudnak Lucy , Rideout-Hanzak Sandra 
Published: July 2007

Fuel distribution in the southern Appalachian Mountain region was measured in over 1000 study plots that were stratified by topographic position (aspect and slope position) and disturbance history. Few fuel differences occurred among topographic positions for undisturbed plots, indicating that fuel accumulation is no greater on highly productive sites than on less productive sites. Litter was slightly higher on undisturbed upper slopes (4.2 t/ha) than on lower slopes (3.7 t/ha) but woody fuels showed no significant differences. Rhododendron ( Rhododendron spp.) and mountain laurel ( Kalmia latifolia L.) were less common than expected, occurring on 25% and 42% of sampled plots, respectively. Disturbance history and type played a greater role in determining fuel loads than did topographic position. Disturbances had occurred on 30% of sample plots within the past 10 years and were most common on exposed slopes. Litter was significantly lower in burned plots (3.5 t/ha vs. 4.0 t/ha in undisturbed plots). One-hour fuels (1.0 t/ha) were significantly higher on beetle-killed plots than on undisturbed plots (0.7 t/ha) while larger woody fuels tended to be greater in plots subjected to beetle attack, fire, and wind.
Modeling long-term tree growth curves in response to warming climate: test cases from a subtropical mountain forest and a tropical rainforest in Mexico
Authors: Ricker Martin , Gutiérrez-García Genaro , Daly Douglas C. 
Published: July 2007

The Earth’s temperature has increased 0.6 °C over the last 100 years, and further climate change is predicted to potentially raise it by 3.5 °C over the next century. More than half of the global annual net primary production of biomass is estimated to occur in the tropics, especially tropical evergreen forest. In temperate forests, increasing temperature may extend the non-frost growing season, and thus increase the CO2sequestration rate, but some authors have also suggested a negative impact of warming in tropical forests from decreased photosynthetic activity. Using the PL model (Ricker and del Río 2004), we forecast growth of two Mexican tree species after climate warming. The model predicts the high-mountain species Pinus hartwegii Lindl. to decrease its expected relative growth throughout its lifetime by 10.6% as a consequence of a 0.6 °C temperature increase; in contrast, the tropical rainforest species Diospyros digyna Jacq. is predicted to increase its expected relative growth throughout its lifetime by 25.4%. The key factor appears to be the expected relationship between temperature and precipitation, rather than temperature alone. While one cannot expect a universal response across sites, some standing tropical rainforests such as those at Los Tuxtlas in Mexico may constitute a carbon sink in a changing climate.
Upper Palaeozoic tectono-sedimentary evolution of the Arabian and adjoining plates
Authors: HUSSEINI M. I. 
Published: July 2007

From the Devonian to possibly the early Carboniferous, the Arabian and adjacent plates were structurally affected by a regional Hercynian (Variscan) tectonic event. This tectonic event is interpreted to be the crustal response to regional compression caused by the initiation of subduction of the Palaeo-Tethyan oceanic crust near the margin of Gondwana along Turkey and Iran. The uplifted areas associated with this tectonic event were largely eroded during the late Carboniferous and early Permian when glacio-fluviatile and marginal marine conditions prevailed.
The Palaeozoic era closed in the late Permian with a major transgression which deposited massive carbonates over most of a peneplaned Arabian plate. Also in late Permian, as well as Triassic, active rifting along the Zagros suture projected extensional stresses across the Arabian plate causing substantial extensional movements along most major basement-controlled, fault systems.
GOLDFINDER: a knowledge-based system for mineral prospecting
Authors: HAWKES D. D. 
Published: July 2007

GOLDFINDER is a prototype knowledge-based system which assesses the potential of a gold prospect and gives advice on the best locality to site a drill hole. By interaction with the user, the system establishes a dynamic database containing, at a sophisticated level, information about the main lithologies, the nature of any mineralization or alteration, and the structural features of the prospect. Using a method of intersecting loci, the system locates a drill site with a precision governed only by the scale of the prospect map.
GOLDFINDER is written in PROLOG within a Macintosh environment and utilizes an interpreter based on two-valued logic. Knowledge is coded partly as semantic networks but mainly as a production system with a structured rule base. A conventional ‘how’ explanation is improved by appending the reason why the expert included a particular rule. A powerful ‘what if’ facility enables the geologist to change the parameters and use the system for modelling purposes. At present, the domain of GOLDFINDER is restricted to Archaean greenstone belts. The present knowledge base could be removed to provide a shell for prospecting any metalliferous mineral deposit.
Anatomical Limitations of Transtibial Drilling in Anterior Cruciate Ligament Reconstruction
Authors: Heming James F. , Rand Jason , Steiner Mark E. 
Published: July 2007

Background Recommended techniques for transtibial drilling in anterior cruciate ligament reconstruction are based on strategies to prevent graft impingement and preserve tibial tunnel length. The limitations of this drilling technique may restrict the ability to centralize tunnels in the anterior cruciate ligament footprints. Hypothesis A transtibial drilling starting point to centralize the tibial and femoral tunnels in their respective footprints can be identified, but it will result in a short tibial tunnel. Study Design Descriptive laboratory study. Methods The femoral and tibial attachments of the anterior cruciate ligament were characterized in 12 fresh-frozen cadaveric knees. Knees were secured in 70° and 90° of flexion. A guide pin was drilled antegrade through the central femoral and proximal anterior cruciate ligament attachment sites through the central tibial anterior cruciate ligament attachment site to exit on the anterior tibia. Results In 90° of flexion using the central femoral and tibial attachment sites, the exit point of the pin on the anterior tibia was 14.1 mm from the tibial joint line and 20.9 mm anterior to the superficial medial collateral ligament. The length of the pin in the tibia was 30.6 mm. Extending the knee to 70° or directing the pin through the proximal femoral anterior cruciate ligament attachment moved the starting point less than 4 mm from this point. Conclusion The transtibial technique can produce tunnels centered in the anterior cruciate ligament footprints, but a starting point close to the tibial joint line is required. This will result in a relatively short tibial tunnel. Clinical Relevance If tunnels centered in the anterior cruciate ligament attachment sites are desired with the transtibial drilling technique, then a short tibial tunnel is necessary. A short tibial tunnel may compromise graft fixation and graft incorporation, or it may result in a tunnel length—graft length mismatch. An alternative drilling strategy might be employed.
Muscle Strength after Anterior Shoulder Stabilization
Authors: Rhee Yong Girl , Lim Chan Teak , Cho Nam Su 
Published: July 2007

Background A number of reports have been made on the muscle strength at the last follow-up after arthroscopic or open Bankart repairs. Few have analyzed the change over time in muscle strength and compared the changes between different operative methods. Hypothesis Muscle strength recovers faster after arthroscopic Bankart repair than after open Bankart repair, and the final muscle strength is not different between the 2 procedures. Study Design Cohort study; Level of evidence, 2. Methods Sixty patients with anterior shoulder instability and an isolated Bankart lesion were enrolled for this study. Thirty patients underwent open Bankart repair (open group), and 30 patients went through arthroscopic Bankart repair (arthroscopic group). Results The open group demonstrated markedly weaker muscle strength during forward elevation than did the arthroscopic group up to 3 months after surgery, but the difference narrowed to about 5% at 6 months (P = .074). At 6 months after surgery, the muscle strength of the open group measured 85.8% ± 11.5% in forward elevation, 89.5% ± 10.3% in external rotation, and 89.3% ± 13.3% in internal rotation. The corresponding figures of the arthroscopic group were 90.6% ± 8.6%, 92.1% ± 9.1%, and 92.1% ± 11.7%. As for external and internal rotations, the open group demonstrated markedly weaker muscle strength 6 weeks after surgery, but the differences were reduced to about 6% and 4%, respectively, at 3 months (P = .092 and .163, respectively). There was no statistically significant difference in final muscle strength 12 months after the operation between the 2 groups (P = .503, .468, and .659, respectively). Conclusion Muscle strength recovered faster with an arthroscopic procedure than with an open procedure during the early postoperative periods, and strength was restored to the level of the unaffected side at 6 months postoperatively. In the group with open Bankart repairs, the muscle strength during forward elevation recovered slower than did external and internal rotation muscle strengths.
Low glucose level and low pH alter the electrochemical function of human parietal pleura
Authors: Kouritas V. K. , Hatzoglou C. , Foroulis C. N. , Hevas A. , Gourgoulianis K. I. , Molyvdas P. A. 
Published: July 2007

The aim of the present study was to investigate whether low glucose and pH level, which are usually measured in complicated pleural effusions, alter the electrochemical function of healthy human parietal pleura.Parietal pleural pieces were stripped from 66 patients during thoracic surgery and were mounted in Ussing chambers. Krebs’ solutions containing different glucose levels (0, 40 and 100 mg) and balanced at different pH levels (7.4, 7.3 and 7.2) were added to the pleural cavity surface of the pieces. Transmesothelial potential difference was measured at various time-points as an electrophysiological variable and transmesothelial resistance (RTM) was calculated using Ohm's law.When normal-glucose Krebs at pH 7.45 was used,RTMremained unchanged over time, but when low-glucose Krebs was used,RTMdecreased. Krebs without glucose caused the greatest decrease inRTM. Use of low-pH Krebs decreasedRTM. The lower the pH of the Krebs, the faster the decrease inRTMand the greater the effect. The decrease inRTMwas greater with low-pH than with low-glucose Krebs. Low glucose and low pH caused an additive decrease inRTM.Low glucose concentration and low pH cause alteration of the electrochemical function of human parietal pleura and could act as agents that lead to further exudate progression.