bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dendrochronological reconstruction of spruce budworm outbreaks in northern Maine, USA
Authors: Fraver Shawn , Seymour Robert S. , Speer James H. , White Alan S. 
Published: July 2007

Using dendrochronological analyses, we reconstructed a 300 year history of eastern spruce budworm ( Choristoneura fumiferana (Clem.)) outbreaks in northern interior Maine. By analyzing radial growth patterns from the budworm host, red spruce ( Picea rubens Sarg.), and nonhost, northern white cedar ( Thuja occidentalis L.), we identified five outbreaks beginning ca. 1709, 1762, 1808, 1914, and 1976, all of which have been documented from eastern Canada. However, little or no evidence was found in our study for the 1830s, 1870s, or 1940s outbreaks also documented there. The mean outbreak return interval in our study (67 years) was roughly twice that postulated for eastern Canada. Differences in forest types, and associated stand dynamics, between the regions may explain the longer return intervals, and consequently the absence of these three outbreaks in Maine. Results also indicate that small, slow-growing trees exhibit a budworm signal very similar to that of overstory trees, once tree-ring series have been properly standardized.
Seed banks of an Arizona Pinus ponderosa landscape: responses to environmental gradients and fire cues
Authors: Abella Scott R. , Springer Judith D. , Covington W. Wallace 
Published: July 2007

We measured soil seed banks in 102 plots within a 110 000 ha Arizona Pinus ponderosa landscape, determined seed-bank responses to fire cues and tree canopy types (open or densely treed patches), compared seed-bank composition among ecosystem types, and assessed the utility of seed banks for ecological restoration. Liquid smoke was associated with increased community-level emergence from seed banks in greenhouse experiments, whereas heating to 100 °C had minimal effect and charred P. ponderosa wood decreased emergence. We detected 103 species in seed-bank samples and 280 species in aboveground vegetation. Erigeron divergens was the commonest seed-bank species; with the exception of Gnaphalium exilifolium , species detected in seed banks also occurred above ground. Although a dry, sandy-textured black-cinder ecosystem exhibited the greatest seed density, seed-bank composition was more ecosystem-specific than was seed density. Native graminoids (e.g., Carex geophila and Muhlenbergia montana ) were common in seed banks, whereas perennial forbs were sparse, particularly under dense tree canopies. Our results suggest that (i) smoke may increase emergence from seed banks in these forests, (ii) seed banks can assist establishment of major graminoids but not forbs during ecological restoration, and (iii) seed-bank composition is partly ecosystem-specific across the landscape.
Population and biomass dynamics of trees in a northern hardwood forest at Hubbard Brook
Authors: Siccama Thomas G. , Fahey Timothy J. , Johnson Chris E. , Sherry Thomas W. , Denny Ellen G. , Girdler E. Binney , Likens Gene E. , Schwarz Paul A. 
Published: July 2007

We quantified the dynamics of the tree stratum at Hubbard Brook Experimental Forest (HBEF), New Hampshire, to examine why live biomass reached a plateau in about 1980. Total aboveground biomass increased from 209 Mg·ha–1 in 1981 to 216 Mg·ha–1 in 2001. From 1991 to 2001, in-growth of ≥10 cm diameter at breast height (DBH) trees averaged 4.7 trees·ha–1·year –1 with a corresponding in-growth biomass of 0.29 Mg·ha–1·year–1. Mortality of trees ≥10 cm DBH averaged 5.3 trees·ha–1·year–1 (1.12% of trees·year–1). Dying trees represented 2.24 Mg·ha–1·year–1 of aboveground biomass from 1991 to 2001. The biomass pools of standing dead, snags, and coarse woody debris in this forest currently are near steady state with residence times of 7.5, 15, and 6.2 years, respectively. The plateau in live biomass was mostly associated with lower wood production. Aboveground net primary productivity was estimated at 6.53 Mg·ha–1·year–1 (3.28 Mg·ha–1·year–1 for aboveground woody tissues and 3.25 Mg·ha–1·year–1 for leaf production), considerably lower than published estimates for the 1956–1965 period at the HBEF. Net ecosystem productivity in this young, second-growth forest is near zero, indicating that it may not be a sink for carbon.
Concentrations of Ca and Mg in early stages of sapwood decay in red spruce, eastern hemlock, red maple, and paper birch
Authors: Smith Kevin T. , Shortle Walter C. , Jellison Jody , Connolly Jon , Schilling Jonathan 
Published: July 2007

The decay of coarse woody debris is a key component in the formation of forest soil and in the biogeochemical cycles of Ca and Mg. We tracked changes in density and concentration of Ca and Mg in sapwood of red maple ( Acer rubrum L.), red spruce ( Picea rubens Sarg.), paper birch ( Betula papyrifera Marsh.), and eastern hemlock ( Tsuga canadensis (L.) Carr.) in Maine and New Hampshire. We repeatedly sampled 10 logs of each combination of tree species and location at the time of felling and at 2-year intervals for 6 years (birch and hemlock) or 8 years (spruce and maple). We found that density loss was essentially linear for the time period investigated, with birch and maple sapwood decaying at faster rates than spruce and hemlock. Repeated-measures analysis and regression modeling of log-transformed concentrations indicated a significant accumulation of Ca for sapwood of all tree species at both locations (30%–90% increase after 6–8 years of ground contact). Regression estimates of Mg concentration in spruce and maple declined about 20% during the 8 years of ground contact. There was no significant trend for Mg concentration in birch and hemlock. Variation in decay rates and trends in Ca and Mg concentration may be due to differences in sapwood quality, the community of wood decay fungi and associated organisms, or to abiotic conditions.
Comparing effective dispersal in expanding population ofPinus sylvestrisandPinus nigrain calcareous grassland
Authors: Debain Sandrine , Chadœuf Joël , Curt Thomas , Kunstler Georges , Lepart Jacques 
Published: July 2007

Accurate predictions about plant invasions require estimation of demographic and dispersal parameters in low-density, expanding populations. We used inverse modelling on the spatial distribution of seedlings to estimate the effective reproductive rate and dispersal parameters in expanding populations of native Pinus sylvestris L. and non-native Pinus nigra Arnold in the Causse Méjean, southern France. The objective was to compare the ability of these two species to colonize these calcareous grasslands. Four empirical models of dispersal were compared. The mixed discrete dispersal kernels had the best fit (lower Aikake information criterion), whereas other candidate models underestimated the tail of the dispersal curve. However, the alternative functions performed quite similarly. The models showed clear differences between P. sylvestris and P. nigra, with the latter species having a higher net reproductive rate and higher effective dispersal. Our results based on the effective dispersal of seedlings over 4 years of age predict a faster spread rate for the non-native P. nigra compared with native P. sylvestris. Our results suggest that P. nigra may expand rapidly into the Causse Méjean grasslands in the forthcoming decades.
A shift in the gap dynamics of Betula alleghaniensis in response to single-tree selection
Authors: Webster Christopher R. , Jensen Nicholas R. 
Published: July 2007

We investigated yellow birch ( Betula alleghaniensis Britt.) growth patterns and disturbance frequency before and after the advent of selection harvesting at the Ford Forestry Center in the Upper Peninsula of Michigan, USA, through the use of tree-ring analysis. Based on the boundary-line release detection procedure, 88% of the trees in our sample (n = 67) displayed evidence of at least one moderate or major release. Prior to active forest management, releases were infrequent, and trees that originated during that period had growth histories consistent with establishment after large-scale disturbances (i.e., large canopy gaps, >200 m2). Conversely, tree cohorts that recruited to the canopy more recently displayed a growth pattern suggestive of periodic small gap expansion. Given the declining representation of yellow birch in these forests, the latter strategy, although probably sufficient to prevent extirpation, is unlikely to ensure a sustainable and harvestable population of this and other midtolerants in managed uneven-aged forests. Our results highlight the importance of considering the cumulative influence of infrequent disturbances and chance events on the maintenance of tree species diversity.
Dead wood dynamics in declining balsam fir and spruce stands in New Brunswick, Canada
Authors: Taylor Sarah L. , MacLean David A. 
Published: July 2007

Forest management prescriptions increasingly incorporate snag and downed dead wood (DDW) guidelines. This study utilizes permanent inventory plots to determine dead wood dynamics in 33 balsam fir ( Abies balsamea (L.) Mill.) – spruce ( Picea spp.) (BFSP) and 17 spruce – balsam fir (SPBF) stands in New Brunswick, Canada. Stands were declining, unmanaged, and had a history of recurrent spruce budworm ( Choristoneura fumiferana (Clem.)) outbreaks and aerial insecticide spraying. Fixed-area sampling matched remnants of 1165 dead trees and 864 corresponding pieces of DDW to plot trees that died over the last 15–18 years with known year and cause of death. Declining BFSP stands had the highest accumulation of dead wood (196 m3/ha) compared with SPBF and nondeclining BFSP (122 m3/ha and 77 m3/ha, respectively). Dead wood dynamics were influenced by cause of death, as a function of differences in tree height at death affecting snag decay, fragmentation, and fall. One-half of all dead trees never made a significant contribution to the snag population (25% uprooted and 25% stem breakage), and attrition resulted in only 50% of snags standing with a mean height of 6 m 15–20 years after death. This study will be of direct value to those managing or modeling dead wood dynamics in similar forests.
A carbon-based method for estimating the wetness of forest surface soil horizons
Authors: Ross Donald S. 
Published: July 2007

The degree of wetness in forest surface soils has an effect on chemical and biological processes but is not easily measured. The high spatial variability in carbon (C) concentration creates high variability in water-holding capacity, and gravimetric water content is not informative. Local hydrology can create patchiness in soil moisture, with saturated soils often found near well-drained ones. When sampling to measure such factors as nitrification potential, it would be advantageous to have a simple metric that reflects the relative wetness of the soil. The relationship between C concentration (range 51.5–520.8 g·kg–1) and gravimetric water content was found to be linear for a set of 113 H- and A-horizon samples assumed to be at field capacity. The wetness ratio is defined as the actual water content of a sample divided by the water content predicted by the least squares regression equation based on C concentration (soil water content (kg·kg–1) = 0.080 + 0.0057 soil C concentration (g·kg–1)). Soil moisture retention curves were developed for a small number of samples in the range of 0 to about –10 kPa and showed that the equation predicted that water would be held at relatively high potential. In samples taken from 10 watersheds in the northeastern USA, wetness ratios between 1.25 and 3.1 were associated with soils identified in the field as ranging from wet to boglike. A median ratio of 0.49 was found in a watershed sampled after an extended dry period. At the Sleepers River Research Watershed, high wetness ratios were associated with a high soil calcium concentration, presumably from enriched groundwater. The ratio should be a useful measurement in watershed studies.
Genetic variation in wood shrinkage and its correlations with tree growth and wood density of Calycophyllum spruceanum at an early age in the Peruvian Amazon
Authors: Sotelo Montes Carmen , Beaulieu Jean , Hernández Roger E. 
Published: July 2007

Calycophyllum spruceanum (Benth.) Hook. f. ex Shum. is an important timber tree species in the Peruvian Amazon Basin. Farmers and industry use wood from young trees of this species, so tree breeders should investigate genetic variation in juvenile wood properties to verify whether they can be improved. A previous study using the same provenance/progeny test showed that there was significant genetic variation in tree growth and wood density, that heritability was higher for density than for growth, and that density and growth were positively correlated at 39 months. This paper presents results for wood shrinkage at 39 months and their correlations with tree growth and wood density. Data were collected on thinned trees. Shrinkage values were relatively low when considering wood density of this species. There was significant genetic variation in wood shrinkage due to families within provenances and, in some cases, due to provenances. Heritability estimates were moderately high for linear and volumetric shrinkage (0.37–0.50) and lower for the tangential/radial shrinkage ratio (0.21–0.29) across zones. The genetic correlations that were considered significant ranged from 0.30 to 0.80. In general, genetic correlations suggest that selection of faster-growing trees with higher wood density would result in wood with greater shrinkage and a larger tangential/radial shrinkage ratio.
Soil and foliar chemistry associated with potassium deficiency in Pinus radiata
Authors: Smethurst Philip , Knowles Andrew , Churchill Keith , Wilkinson Ann , Lyons Arthur 
Published: July 2007

We required an improved understanding of K deficiency and diagnosis in Pinus radiata D. Don (radiata pine). A rapid growth response to K fertilization (100 kg·ha–1) in the presence of weed control confirmed K deficiency in a 2-year-old stand. Tree growth did not respond to N fertilization, and weed control alone appeared insufficient to maximize tree growth. Temporal patterns in visual symptoms of K deficiency suggested they were worst at the end of a drought, and improved after several months of above-average rainfall that coincided with an increase in soil temperature. Soil chemistry generally responded predictably to fertilization, but K fertilization increased soil solution Ca and Mg concentrations without changing exchangeable concentrations. With weed control, a doubling of stem growth response to K fertilizer was associated with a 270% increase in soil solution K (natural variation amongst control plots), 51% increase in exchangeable K, and 39% increase in foliar K. Relationships between seedling growth and hydroponic concentrations of K were consistent with the incidence of K deficiency in the field; predicting these deficiencies using soil exchangeable concentrations was less clear. This study advances the interpretation of soil and foliar chemistry in relation to K and Mg deficiency in P. radiata.
Lidocaine Exhibits Dose- and Time-Dependent Cytotoxic Effects on Bovine Articular Chondrocytes in Vitro
Authors: Karpie John C. , Chu Constance R. 
Published: July 2007

BackgroundIntra-articular lidocaine is commonly used.PurposeThis study was conducted to determine whether short-term exposures to 1% and 2% lidocaine are toxic to articular chondrocytes, whether this is due to pH, and whether an intact articular surface is protective.Study DesignControlled laboratory study.MethodsFresh bovine articular chondrocytes in alginate bead cultures were treated with 1% or 2% lidocaine or buffered saline (pH 7.4, 7.0, and 5.0) for 15, 30, or 60 minutes. Chondrocytes were then analyzed for viability by flow cytometry 1 hour, 1 day, and 1 week later. Bovine osteochondral cores with and without the superficial 1 mm of cartilage removed were submerged in either 0.9% saline (pH 7.4) or in 1% or 2% lidocaine for 30 minutes and assessed for viability using fluorescent microscopy.ResultsChondrocyte viability decreased after just 15-minute exposures to 1% lidocaine. Longer exposures to 1% and 2% lidocaine further reduced chondrocyte viability. Chondrotoxicity of 2% lidocaine was greater than 1% lidocaine. There was no difference in chondrocyte viability after exposures to saline solutions of pH 7.4, 7.0, or 5.0. An intact articular surface did not affect lidocaine's chondrotoxic effects.ConclusionResults show dose- and time-dependent cytotoxic effects of lidocaine on bovine articular chondrocytes. Reduction of pH alone did not decrease chondrocyte viability, and the intact articular surface was not protective.Clinical RelevanceAlthough lidocaine chondrotoxicity was less than previously reported with bupivacaine, these observations suggest that local anesthetics as a class of drugs may negatively affect articular cartilage.
Biomechanical Analysis of Distal Biceps Tendon Repair Methods
Authors: Henry Jon , Feinblatt Jeff , Kaeding Christopher C. , Latshaw James , Litsky Alan , Sibel Roman , Stephens Julie A. , Jones Grant L. 
Published: July 2007

Background The 1-incision and 2-incision techniques are commonly used methods to repair a distal biceps rupture, and they differ in the location of reinsertion of tendon into bone. Hypothesis The native distal biceps brachii tendon inserts on the posterior-ulnar aspect of the bicipital tuberosity, which functions as a cam, increasing the tendon's moment arm during its principal action of forearm supination. Repair of the distal biceps tendon to the anterior aspect of the tuberosity compromises forearm supination due to absence of the bicipital tuberosity's cam effect. Study Design Controlled laboratory study. Methods Eleven matched pairs of fresh-frozen cadaveric upper extremities were prepared for repair of the distal biceps tendon using either anterior or posterior reattachment with transosseous suture fixation. Specimens were tested on a materials testing machine with intact distal biceps insertion and after repair. A load cell at the distal radial-ulnar joint measured resultant elbow flexion and forearm supination torque produced by 100-N force applied to the proximal aspect of the tendon. Results Although there was a trend (P = .104) toward loss of supination torque with the anterior reconstruction method, no significant differences in torque (0.80 vs 0.89 N·m) or flexion force (11.87 vs 12.07 N) were found between the anterior and posterior reconstruction techniques. Conclusion There is no statistically significant difference in flexion force or supination torque between the anterior and posterior reconstruction techniques. Clinical Relevance This study supports existing limited clinical data suggesting no functional differences exist between 2 common repair methods. Further biomechanical and clinical investigations directly comparing the results of distal biceps tendon repairs made to the anterior aspect versus the posterior aspect of the tuberosity are necessary to definitely determine if differences exist in resultant elbow flexion and forearm supination functions.
Premature cardiovascular disease after allogeneic hematopoietic stem-cell transplantation
Authors: Tichelli André , Bucher Christoph , Rovó Alicia , Stussi Georg , Stern Martin , Paulussen Michael , Halter Jörg , Meyer-Monard Sandrine , Heim Dominik , Tsakiris Dimitrios A. , Biedermann Barbara , Passweg Jakob R. , Gratwohl Alois 
Published: July 2007

AbstractWe assessed incidence and risk factors of cardiovascular events in 265 patients undergoing allogeneic hematopoietic stem-cell transplantation (HSCT) between 1980 and 2000 and who survived at least 2 years. Results were compared with a cohort of 145 patients treated during the same period with autologous HSCT. The median age of patients with allogeneic HSCT at last follow-up was 39 years, and median follow-up was 9 years. Eighteen (6.8%) patients after allogeneic and 3 (2.1%) patients after autologous HSCT experienced an arterial event. The cumulative incidence of first arterial event after allogeneic HSCT was 22.1% (95% CI, 12.0-40.9) at 25 years. The cumulative incidence 15 years after allogeneic HSCT was 7.5% as compared with 2.3% after autologous HSCT. Adjusting for age, risk of an arterial event was significantly higher after allogeneic HSCT (RR 6.92; P =.009). In multivariate analysis, allogeneic HSCT (RR: 14.5; P =.003), and at least 2 of 4 cardiovascular risk factors (hypertension, dyslipidemia, diabetes, obesity) (RR: 12.4; P =.02) were associated with a higher incidence of arterial events after HSCT. Thus, long-term survivors after allogeneic HSCT are at high risk for premature arterial vascular disease. HSCT might favor the emergence of established risk factors, such as hypertension, diabetes, and dyslipidemia.
Immunomodulatory properties of mesenchymal stromal cells
Authors: Nauta Alma J. , Fibbe Willem E. 
Published: July 2007

Abstract
Mesenchymal stem cells (MSCs) are multipotential nonhematopoietic progenitor cells capable of differentiating into multiple lineages of the mesenchyme. MSCs have emerged as a promising therapeutic modality for tissue regeneration and repair. Further clinical interest has been raised by the observation that MSCs are immunoprivileged and, more importantly, display immunomodulatory capacities. Although the mechanisms underlying the immunosuppressive effects of MSCs have not been clearly defined, their immunosuppressive properties have already been exploited in the clinical setting. The aim of this review is to critically discuss the immunogenicity and immunomodulatory properties of MSCs, both in vitro and in vivo, the possible underlying mechanisms, the potential clinical use of MSCs as modulators of immune responses in vivo, and to indicate clinical safety concerns and recommendations for future research.
Megakaryocyte-restricted MYH9 inactivation dramatically affects hemostasis while preserving platelet aggregation and secretion
Authors: Léon Catherine , Eckly Anita , Hechler Béatrice , Aleil Boris , Freund Monique , Ravanat Catherine , Jourdain Marie , Nonne Christelle , Weber Josiane , Tiedt Ralph , Gratacap Marie-Pierre , Severin Sonia , Cazenave Jean-Pierre , Lanza François , Skoda Radek , Gachet Christian 
Published: July 2007

AbstractMutations in the MYH9 gene encoding the nonmuscle myosin heavy chain IIA result in bleeding disorders characterized by a macrothrombocytopenia. To understand the role of myosin in normal platelet functions and in pathology, we generated mice with disruption of MYH9 in megakaryocytes. MYH9Δ mice displayed macrothrombocytopenia with a strong increase in bleeding time and absence of clot retraction. However, platelet aggregation and secretion in response to any agonist were near normal despite absence of initial platelet contraction. By contrast, integrin outside-in signaling was impaired, as observed by a decrease in integrin β3 phosphorylation and PtdIns(3,4)P2 accumulation following stimulation. Upon adhesion on a fibrinogen-coated surface, MYH9Δ platelets were still able to extend lamellipodia but without stress fiber–like formation. As a consequence, thrombus growth and organization, investigated under flow by perfusing whole blood over collagen, were strongly impaired. Thrombus stability was also decreased in vivo in a model of FeCl3-induced injury of carotid arteries. Overall, these results demonstrate that while myosin seems dispensable for aggregation and secretion in suspension, it plays a key role in platelet contractile phenomena and outside-in signaling. These roles of myosin in platelet functions, in addition to thrombocytopenia, account for the strong hemostatic defects observed in MYH9Δ mice.