bluuebunny/crossref_metadata_2025 huggingface dataset:
What's in Your 403(b)? Academic Retirement Plans and the Costs of Underdiversification
Authors: Angus John , Brown William O. , Smith Janet Kiholm , Smith Richard
Published: October 2008

Sponsors of defined contribution retirement plans typically limit the investment choices of plan participants to a small number of investment managers and a limited number of investment vehicles. Such restrictions may limit excessive risk‐taking by participants but also may preclude opportunities for efficient diversification. Many college and university 403 (b) plans have restricted investment choices to the retirement annuities offered by TIAA‐CREF, the current manager of over half of all 403(b) contributions. Using 10 years of historical data, we study the efficiency of this TIAA‐CREF opportunity set relative to a larger set that includes several standard index funds. Extrapolations must be interpreted ‐with caution. Assuming optimal rebalancing, depending on loss aversion and diversification constraints, the historical sample of returns implies that over a 20‐year remaining work life, an employee ‐with an expanded menu that includes standard index funds could gain over 40% in terminal wealth compared to one who is restricted to TIAA‐CREF retirement annuities. Even when a naive diversification strategy of equally weighting (1/n) all available funds is used, the expandedmenu outperforms the restricted portfolio by more than 25% over20years. These differences generally are significant at conventional levels based on parametric and nonparametric testing and do not appear to result from idiosyncratic market performance durinz the sample period.
Intra‐lndustry Effects of Corporate Capital Investment Announcements
Authors: Chen Sheng‐Syan , Ho Lan‐Chih , Shih Yi‐Cheng
Published: October 2008

We examine how announcements of corporate capital investments by one firm affect the stock prices of its competitors. We find that on average, rivals experience a signifi cantly negative valuation effect. The results suggest that for the sample as a whole, the competitive effect dominates the contagion effect. We further examine various factors that could potentially explain the heterogeneous intra‐industry effects of capital investment announcements. We find that rivals' share prices are more adversely affected when the announcer experiences a higher announcement effect or is the first mover in the industry. We also show that rivals experience a greater wealth loss when they have poorer investment opportunities or higher financial leverage.
Impact of Visibility and Investment Advisor Credibility on the Valuation Effects of High‐Tech Cross‐Border Acquisitions
Authors: Benou Georgina , Gleason Kimberly C. , Madura Jeff
Published: October 2008

Since foreign high‐tech firms exhibit a high level of asymmetric information, there is much investor skepticism surrounding the potential benefits to US firms that acquire them. However, the investor perception may be more favorable when the acquisitions involve more visible targets and advice from investment banks with a strong reputation. Based on a sample of 503 high‐tech cross‐border acquisitions, bidding‐firm shareholders experience positive but statistically insignificant valuation effects overall. However, bidder firms experience positive and significant valuation effects when the foreign high‐tech target receives a high level of media attention and when the acquisition is endorsed by a top‐tier investment bank. Visibility and credibility enhance the perceived benefits of acquiring foreign targets that have substantial intangible assets and a high level of asymmetric information.
The Models of Power Shifts: An Explanation for the Cycle of Ups‐and‐Downs in Sino‐U.S. Relations
Authors: Liping Zhang
Published: October 2008

The author tries to build an explanatory model for the cycle of ups‐and‐downs in Sino‐U.S. Relations by analyzing the factors, mechanisms and processes in the decision‐making. She then examines the legitimacy and limitations of this model through appraising the influences of both presidential power shift and Congressional power shift on U.S. China policy in the past 30 years. She concludes that the cycle of Sino‐U.S. relations will still probably parallel with the cycle of American power shift in the future if we hold the international factors and China factors constant.
Division of Innovative Labor Between the U.S. and Japan in Asia‐Pacific Technology Markets: Evidence from the Licensing Contracts of American and Japanese Firms with Korean Firms*
Authors: Kim Taekwon
Published: October 2008

This paper empirically investigates the role of the U.S. and Japan in the Asia‐Pacific technology market, in particular, their relationship with Korea based on a survey data set.

Korean firms tend to import their technologies from the U.S. rather than from Japan for new business expansion and enhancing technological capabilities, while Japanese technol‐ogies are more likely to be imported for domestic market expansion through quality improvement and production capacity expansion. The relationship between the licensor and licensee is more likely to be vertical for the technologies imported from the U.S. than Japanese ones. Compared with the technologies from the U.S., Japanese technologies are cheaper and are easier to find alternatives. The licensees that imported technologies from Japan tend to care more about the current or ongoing relation‐ship with existing relational networks such as the existing licensor and/or joint‐venture partners as the information channel for technology import decisions. U.S. technologies have been more likely to be the pathfinder for Korean companies in developing new markets, developing new products, upgrading technological capabilities. Technologies from the U.S. and Japan have been utilized for different market segments with different strategic purposes.
A Comparative Analysis of President Clinton and Bush's Handling of the North Korean Nuclear Weapons Program: Power and Strategy*
Authors: Kim Ilsu
Published: October 2008

The purposes of this paper are: 1) to examine and analyze how the two presidents' policy goals in dealing with North Korea actually materialized; 2) to illustrate how these two Presidents implement their policy goals toward North Korea; 3) to discuss the Congressional responses to the president's policy goals toward North Korea; and 4) to provide comparative analysis of the two presidents' handling of North Korea. This study shows that different Presidents have dealt with North Korean issues in different ways. Two such presidents, Bill Clinton and George W. Bush, tried at the beginning of their terms as president to ignore the brewing problems in North Korea. However, both were forced to solve the North's nuclear issues early on in their respective administrations. Their decisions in dealing with North Korean nuclear capabilities help to define their early reputations as foreign policy makers. Yet, the domestic as well as international contexts that President Clinton and Bush faced were somewhat different. President Clinton maintains that the North's nuclear crisis arose from North Korea's security fears: Abandoned by its two Cold War patrons, economically bankrupt, and internationally isolated, the North Korean government saw the pursuit of nuclear weapons and ballistic missiles as the only path to survival and security for their regime. In this regard, Clinton's actual efforts to resolve the issues surrounding the North's nuclear program appeared ambiguous and inconsistent. This led to the temporary suspension of the North's nuclear ambitions through an Agreed Framework. However, President Bush stuck to more of a hardnosed approach. He continues to demand a complete, verifiable and irreversible dismantling of the nuclear program first, before any provision of economic or humanitarian assistance is extended toward North Korea. Bush favors multilateral negotiations, which leads the DPRK to feel more isolated than before. Although the second six‐party talks ended without a major breakthrough, it seems that all parties except the North think the meeting was successful in terms of lowering tensions in Korea. This case study demonstrates several observable features that characterize the president's role in shaping North Korean policy. A president who wants to take a new approach to some element of U.S. policy can be caught between the diplomat's desire for flexibility and the power of domestic political forces. The president can achieve success, but only if the new direction in policy finds acceptance on Capitol Hill.
The Decision Process of the Trusteeship in Korea, 1945–1946: Focusing on the Change of U.S. Ideas
Authors: Shin Bok‐ryong
Published: October 2008

The U.S. decision to enact Trusteeship of Korea after the liberation in 1945 was a prelude of a tragedy in Korean contemporary history, which extended to the separation of the peninsula. Both the U.S. and the USSR had no reason to hasten the independence or unification of Korea. They needed “to stay in Korea” for more influence in Korea, without engendering blame for imperialist rule or anti‐colonial resistance. The American plan and Russian approval on the trusteeship in Korea was the best choice to secure sharing a portion of Korea in the name of international trusteeship. This would exempt them from the danger of dominance by one power in Korea. From the U.S. point of view, such a trusteeship system would delay Korean independence, but would have the virtue both of acknowledging the Soviet interest in Korea and of hamstringing and confining Moscow's expansionist impulses. Furthermore, the divided occupancy was the only co‐factor that satisfied the interests of both the Soviet Union and the U.S. The Soviet Union was determined to establish a Soviet‐friendly country in the Korean peninsula, while the U.S. wanted a buffer zone against the spread of the Cold War with the Soviet Union. Trusteeship was impossible to implement until both countries could totally agree on the issues, which meant the trusteeship was impossible from the start. After the death of American President F. D. Roosevelt, the Truman Administration was initially willing to abolish the trusteeship as long as America did not lose dominance in Korea. However, the U.S. could not explicitly publicize this idea, because they wanted to eschew any accusations of being a promise breaker.
Important Economic Issues Affecting Japan and its Pan‐Asian Relationships
Authors: Hatakeyama Noboru
Published: October 2008

Restructuring within big companies other than banks is almost over. In most cases, large manufacturers are finished with layoffs, reduction of debts, and curtailment of excessive capacities. However, SMEs, service industries, banks and the agricultural sector are still in need of new methodologies and structures to enhance growth and productivity.

Structural reform pursued by GOJ has done a good job in reducing public works. Money and resources, including workers, previously allocated to the public works has been shifted to more constructive areas after necessary arrangements.

However; deregulation or regulatory reform, an important part of structural reform, has not been properly prioritized. Time and resources for structural reform is limited. Top priority should be given to deregulatory practices that will lead to increased efective demands in Japan b marketplace, and within Asian and international markets.
Adrenal incidentaloma: evaluation and management
Authors: Singh P K , Buch H N
Published: October 2008

Adrenal incidentalomas are adrenal masses discovered incidental to imaging studies performed for reasons unrelated to adrenal pathology. Although most adrenal incidentalomas are non-functioning benign adenomas, their increasing prevalence presents diagnostic and therapeutic challenges. The assessment of adrenal incidentalomas is aimed at deciding whether or not the tumour should be surgically removed. Adrenalectomy is indicated for phaeochromocytoma, other symptomatic hormone-secreting tumours and those with a high risk of malignancy. Biochemical screening for tumour hypersecretion is mandatory in all adrenal incidentalomas, since hormone secreting tumours may be clinically silent. The diagnosis of phaeochromocytoma is of paramount importance because of its life-threatening complications. Non-functioning adrenal incidentalomas need assessment for risk of malignancy, and this is based on the size of the tumour and its imaging characteristics. An observational policy with periodic radiological and biochemical reassessment is pursued in patients with non-functioning incidentalomas with low malignancy risk. The duration and frequency of reassessment remains unclear, as the natural history of adrenal incidentalomas has yet to be clearly defined, and there is a lack of controlled studies comparing surgical intervention with observation. However, the possibility of acquiring autonomous hypersecretion or conversion to malignancy in an incidentaloma diagnosed to be a benign non-functioning lesion is very low, and most patients may be safely discharged after an initial follow-up period of 2 years.
Investigation and management of hypertriglyceridaemia
Authors: Ferns G , Keti V , Griffin B
Published: October 2008

While the precise definition of hypertriglyceridaemia remains contentious, the condition is becoming more common in western populations as the prevalence of obesity and diabetes mellitus rise. Although there is strong epidemiological evidence that hypertriglyceridaemia is an independent risk factor for cardiovascular disease, it is has been difficult to demonstrate this by drug intervention studies, as drugs that reduce triglycerides also raise high density lipoprotein cholesterol. Precise target values have also been difficult to agree, although several of the new guidelines for coronary risk management now include triglycerides. The causes of hypertriglyceridaemia are numerous. The more severe forms have a genetic basis, and may lead to an increased risk of pancreatitis. Several types of hypertriglyceridaemia are familial and are associated with increased cardiovascular risk. Secondary causes of hypertriglyceridaemia are also numerous and it is important to exclude these before starting treatment with specific triglyceride-lowering agents. Lifestyle management is also very effective and includes weight reduction, restricted alcohol and fat intake and exercise.
Cerebral toxoplasmosis in a middle-aged man as first presentation of primary immunodeficiency due to a hypomorphic mutation in the CD40 ligand gene
Authors: Yong P F K , Post F A , Gilmour K C , Grosse-Kreul D , King A , Easterbrook P , Ibrahim M A A
Published: October 2008

Cerebral toxoplasmosis can occur outside the setting of advanced HIV immunodeficiency or drug-induced immunosuppression. A case of cerebral toxoplasmosis is reported in a previously healthy 41-year-old man who was found to have a genetic defect in CD40 ligand, resulting in the X linked hyper-IgM syndrome despite normal surface protein expression on flow cytometry. This highlights the fact that primary immunodeficiencies can first present late in life with a relatively mild phenotype and should be considered in the differential diagnosis of opportunistic infections in non-HIV infected patients; in addition, normal protein expression does not necessarily rule out hypomorphic mutations.
Investigation of molecular markers in the diagnosis of refractory coeliac disease in a large patient cohort: Table 1
Authors: O’Shea U , Abuzakouk M , O’Morain C , O’Donoghue D , Sheahan K , Watson P , O’Briain S , Alexander D , Catherwood M , Jackson J , Kelly J , Feighery C
Published: October 2008

Aims:

Some patients with coeliac disease, despite strict adherence to a gluten-free diet, continue to have significant symptoms and/or a severe small intestinal histological lesion. The term “refractory coeliac disease” (rCD) is used to describe this condition. The purpose of this study was to investigate the value of tissue molecular markers reported to help in the diagnosis of rCD.

Methods:

Details on 61 patients with suspected rCD were collected. The clinical and laboratory findings in these patients were carefully evaluated, in part to determine whether patients were adhering to a strict gluten-free diet. The co-expression of CD3 and CD8 on intraepithelial lymphocytes was investigated by monoclonal antibody staining of small intestinal biopsy tissue; a finding of less than 50% CD3+ cells co-expressing CD8 was defined as an aberrant phenotype. T cell receptor gene rearrangement was assessed when a sufficient tissue sample was available.

Results:

A diagnosis of rCD was made in 38 patients based on clinical, laboratory and histological data. An aberrant intraepithelial lymphocyte population was found in 20 of these patients and in this group a clonal T cell population was found in five of seven patients tested. In the remaining 18 patients, the CD3/CD8 ratio was normal and two of seven tested had a clonal T cell population. After detailed monitoring, a diagnosis of rCD was excluded in the remaining 23 patients.

Conclusions:

This study supports the use of phenotypic and T cell clonality investigations in identifying patients with true rCD.
Deficient leucocyte antisedimentation is related to post-stroke infections and outcome
Authors: Molnar T , Peterfalvi A , Szereday L , Pusch G , Szapary L , Komoly S , Bogar L , Illes Z
Published: October 2008

Background:

Patients with stroke are more susceptible to infections, suggesting possible deficiencies of early immune responses, particularly of leucocytes.

Aims:

To serially examine leucocyte antisedimentation rate (LAR), a simple test to detect activation of leucocytes, and correlate it with S100β, procalcitonin and outcome in patients with acute ischaemic events.

Methods:

Venous blood samples were taken from 61 healthy volunteers and 49 patients with acute ischaemic events (acute ischaemic stroke (AIS), n = 38; transient ischaemic attack (TIA), n = 11) within 6 hours, at 24 and 72 hours after onset of symptoms.

Results:

LAR was significantly higher in acute ischaemic events compared to controls within 6 hours after onset of stroke regardless of post-stroke infections. In addition, the increase of LAR was delayed and attenuated in TIA in contrast to AIS. A deficiency in early increase of LAR was associated with post-stroke infections and a poor outcome, measured by the Glasgow Outcome Scale in AIS. There was a positive correlation between LAR and S100β at 72 hours after the onset of ischaemic stroke. Increased levels of S100β at 24 and 72 hours after stroke were associated with poor outcome.

Conclusions:

An early activation of leucocytes indicated by an increase of LAR is characteristic of acute ischaemic cerebrovascular events. A delayed and ameliorated leucocyte activation represented by LAR is characteristic of TIA in contrast to stroke. Deficient early activation predisposes to post-stroke infections related to poor outcome. In addition, the extent of tissue injury correlates with the magnitude of innate immune responses.
Characterization of two families of tandem repeated DNA sequences inPotamogeton pectinatusL.
Authors: Ceccarelli Marilena , Sarri Vania , Minelli Stefania , Gelati Maria Teresa
Published: October 2008

DNA sequences belonging to two families of tandem repeats, PpeRsa1 (362–364 bp in length, 62% A+T residues) and PpeRsa2 (355–359 bp in length, 59% A+T residues), have been isolated from the Potamogeton pectinatus L. genome. The two sequence families do not share significant nucleotide sequence similarity, even if an evolutionary relationship between them could be assumed. The comparison of the cleaving activity of isoschizomeres that are either sensitive or insensitive to methylation of cytosine residues in the target sequence revealed high methylation in both sequence families. The copy number per 1C DNA of PpeRsa1- and PpeRsa2-related sequences is estimated to be 4.92 × 104and 7.96 × 104, respectively. Taken together, these sequences account for about 7.5% of the entire genome of P. pectinatus. The chromosomal organization of these sequences was investigated by fluorescent in situ hybridization. PpeRsa1 and PpeRsa2 repeats found related sequences in 52 chromosomes of the P. pectinatus complement (2n = 78). The related sequences were localized around the centromeres and at the chromosome ends in three pairs of chromosomes, while they were found only at the chromosome ends in the remaining pairs. Twenty-six chromosomes did not show any hybridization signal. The hypothesis that the species is a hybrid between a diploid parent and an allotetraploid parent is put forward.
SSR-based genetic linkage map ofCucurbita moschataand its synteny withCucurbita pepo
Authors: Gong L. , Pachner M. , Kalai K. , Lelley T.
Published: October 2008

The first SSR-based genetic linkage map of Cucurbita moschata was created by integrating the maps of two F2populations with one common parent developed from the crosses Waltham Butternut (WB) × Nigerian Local (NL) and ZHOU (a hull-less type) × WB. The integrated C. moschata map comprises 205 SSR markers and two morphological traits (Gr and n). The map is composed of 27 linkage groups with a marker density of 7 cM. Comparing the C. moschata map with the published Cucurbita pepo map, we found a high level of macrosynteny. Seventy-two of 76 common SSR markers between C. moschata and C. pepo were located in homologous linkage groups. These markers in general have conserved orders and similar genetic distances; they represent orthologous loci. A reference map based on these SSRs was obtained. No major chromosomal rearrangement between the two species could be detected at present, although four SSR markers were mapped in nonhomologous linkage groups. The comparative alignment of SSR markers did not provide any indication of a possible ancient polyploid origin of the species. The comparative mapping of C. moschata and C. pepo reported here will be useful for further studies on Cucurbit evolution, gene isolation, and breeding work.
Development of an Adonis aestivalis expressed sequence tag population as a resource for genes of the carotenoid pathway
Authors: Li Rong , Links Matthew G. , Gjetvaj Branimir , Sharpe Andrew , Hannoufa Abdelali
Published: October 2008

Expressed sequence tag (EST) libraries are a powerful tool for gene discovery in plants with genomes that are not fully sequenced. Adonis aestivalis (Ranunculaceae) is unusual among higher plants in that it accumulates large amounts of the valuable red ketocarotenoid astaxanthin in the flower petals, in addition to other carotenoids, and should therefore be a rich source of transcripts involved in carotenoid biosynthesis. To create a resource for gene discovery and increase our understanding of ketocarotenoid biosynthesis in plants, we sequenced 4189 cloned cDNAs from the floral tissues of A. aestivalis. The EST collection was annotated using sequence homology searches comparing the A. aestivalis ESTs with reference databases. ESTs involved in carotenoid biosynthesis were identified based on sequence homology to published sequences and by functional prediction using InterProScan. This study identified expressed transcripts for most of the known genes involved in the carotenoid pathway. Using an Escherichia coli functional expression system, two candidate transcripts from the A. aestivalis cDNA library were functionally characterized and identified as a novel β-carotene 3-hydroxylase (CrtH2) and a β-carotene monooxygenase. The expanded use of this EST collection combined with the E. coli expression system as presented here will greatly facilitate the cloning and characterization of candidate genes involved in carotenoid biosynthesis in plants.
Quantitative trait loci associated with lettuce seed germination under different temperature and light environments
Authors: Hayashi Eiji , Aoyama Natsuyo , Still David W.
Published: October 2008

Temperature and light are primary environmental cues affecting seed germination. To elucidate the genetic architecture underlying lettuce ( Lactuca sativa L.) seed germination under different environmental conditions, an F8recombinant inbred line population consisting of 131 families was phenotyped for final germination and germination rate. Seeds were imbibed in water at 20 °C under continuous red light (20-Rc), 20 °C continuous dark (20-Dc), 31.5 °C continuous red light (31.5-Rc), 31.5 °C continuous dark (31.5-Dc), or 20 °C far-red light for 24 h followed by continuous dark (20-FRc-Dc). Thirty-eight quantitative trait loci (QTL) were identified from two seed maturation environments: 10 for final germination and 28 for germination rate. The amount of variation attributed to an individual QTL ranged from 9.3% to 17.2% and from 5.6% to 26.2% for final germination and germination rate, respectively. Path analysis indicated that factors affecting germination under 31.5-Rc or 31.5-Dc are largely the same, and these appear to differ from those employed under 20-FRc-Dc. QTL and path analysis support the notion of common and unique factors for germination under diverse temperature and light regimes. A highly significant effect of the seed maturation environment on subsequent germination capacity under environmental stress was observed.
Evolution of cassava (Manihot esculentaCrantz) after recent introduction into a South Pacific Island system: the contribution of sex to the diversification of a clonally propagated crop
Authors: Sardos J. , McKey D. , Duval M. F. , Malapa R. , Noyer J. L. , Lebot V.
Published: October 2008

Cassava ( Manihot esculenta Crantz) is a clonally propagated crop that was introduced into the South Pacific archipelago of Vanuatu in the 1850s. Based on a survey conducted in 10 different villages throughout the archipelago, we present here a study of its diversity. Farmers’ knowledge about cultivation cycle and sexual reproduction of cassava was recorded during group interviews in each village. Using a set of 11 SSR markers, we genotyped the 104 landraces collected and 60 supplementary accessions from a within-landrace study (12 landraces × 5 plants). Out of the 104 landraces collected, we discovered 77 different multilocus genotypes and the within-landrace study identified several polyclonal landraces. Our data suggest a number of hypotheses about the dynamics of diversity of cassava in Vanuatu.
Root-rotting fungi in white spruce, black spruce, and balsam fir in northern Ontario
Authors: Whitney R.D.
Published: October 2008

Fungi associated with root rot in living trees were isolated and identified from 521 white spruce (Piceaglauca (Moench) Voss), 1342 black spruce (Piceamariana (Mill.) B.S.P.), and 1383 balsam fir (Abiesbalsamea (L.) Mill.) ranging in age from 26 to 208 years (at a 30-cm height), in 165 stands across northern Ontario. Trees were pulled out with the winch of a skidder, root decays and stains were measured, and cultures were made from root and butt sections. Armillaria spp., considered in this study to be mostly Armillariaostoyae (Romagn.) Herink, was the most frequently isolated fungus, occurring in 32, 34, and 46% of white spruce, black spruce, and balsam fir, respectively. Inonotustomentosus (Fr.:Fr.) S. Teng, Scytinostromagalactinum (Fr.) Donk, and Coniophoraputeana (Schumach.:Fr.) P. Karst. were next in frequency, in that order. An additional 26 Basidiomycetes were associated with lesser amounts of root rot in the three species. Armillariaostoyae infected, and remained mostly below ground in all three species, averaging less than 0.3 m in height up the stem in living trees, while most of the other major fungi advanced more than 0.5 m up the stem in average infected trees. The frequency of A. ostoyae in white spruce and black spruce increased with tree age to about 90 and 130 years, respectively, then leveled off, probably because of diseased trees falling from the stand. An age relationship was not found with this fungus in balsam fir. The other fungi generally increased in frequency of occurrence with tree age. The only major fungus that attacked living tissues (sapwood) exclusively to any extent was A. ostoyae. Some less frequent fungi such as Resiniciumbicolor (Albertini & Schwein.:Fr.) Parmasto and Serpulahimantioides (Fr.:Fr.) P. Karst. indicated pathogenicity by attacking sapwood initially. Armillariaostoyae infected significantly higher numbers of black spruce and balsam fir growing on dryer sites (soil moisture regimes (SMR) 1–3) than on wet sites (SMR 5–7). The only other fungus apparently related to moisture regime was unknown F, which infected black spruce more on wet than on dry sites. Significantly higher proportions of root and buttwood of all three species were infected with A. ostoyae and I. tomentosus in northwestern Ontario than in northeastern Ontario. Heavy to severe root rot caused tree height or diameter growth reductions when trees were infected by either A. ostoyae or I. tomentosus. An Ascomycete, Ascocorynesarcoides (Jacq.) Groves & D.E. Wilson, was associated with pink or faint brown stains, often near bark seams, in white spruce and black spruce. It was isolated from roots of 20 and 28% of these species, respectively.
Influence of carbon and nitrogen on cellulose and lignin degradation in forest soils
Authors: Entry James A. , Backman Carole B.
Published: October 2008

The concentration of lignin in plant tissue is a major factor controlling organic matter decomposition rates in terrestrial ecosystems. Microcosms were used to determine the influence of C and N additions on active bacterial and active fungal biomass, cellulose degradation, and lignin degradation at 4, 8, and 12 weeks in soils from the Tuskeege National Forest in southern Alabama. Active bacterial and active fungal biomass was determined by direct microscopy; cellulose and lignin degradation were measured radiometrically. The experimental design was a 33 latin square. Treatments were as follows: soil type, soil C (soils amended with the equivalent of 0, 400, or 800 kg C•ha−1 as cellulose), and soil N (soils amended with the equivalent of 0, 250, or 500 kg N•ha−1 as NH4NO3). Active bacterial biomass, active fungal biomass, and cellulose and lignin degradation did not differ with soil type. Active bacterial biomass was not affected by N or C additions. As C and N concentrations increased, active fungal biomass as well as cellulose and lignin degradation increased. The concentration of C and N (together) in the soil correlated with both cellulose and lignin degradation (r2 = 0.76, p < 0.001; r2 = 0.44, p < 0.001, respectively). Active fungal biomass correlated curvilinearly with both cellulose and lignin degradation (r2 = 0.38, p < 0.001; r2 = 0.33, p < 0.001, respectively). The lignin:N ratio is often used to predict organic matter decomposition rates in terrestrial ecosystems. These results lead us to conclude that a cellulose:lignin:N ratio may be a more accurate predictor of organic matter decomposition rates than C:N ratio or lignin:N ratios.
Effects of elevated CO2 and N fertilization on soil respiration from ponderosa pine (Pinusponderosa) in open-top chambers
Authors: Vose James M. , Elliott Katherine J. , Johnson Dale W. , Walker Roger F. , Johnson Mark G. , Tingey David T.
Published: October 2008

We measured growing season soil CO2 evolution under elevated atmospheric CO2 and soil nitrogen (N) additions. Our objectives were to determine treatment effects, quantify seasonal variation, and determine regulating mechanisms. Elevated CO2 treatments were applied in open-top chambers containing 3-year-old ponderosa pine (Pinusponderosa Dougl. ex Laws.) seedlings. Nitrogen applications were made annually in early spring. The experimental design was a replicated factorial combination of CO2 (ambient, + 175, and + 350 μL•L−1 CO2) and N (0, 10, and 20 g•m−2 N as ammonium sulfate). Soils were irrigated to maintain soil moisture at >25%. Soil CO2 evolution was measured over diurnal periods (20–22 h) in April, June, and October 1993 using a flow-through, infrared gas analyzer measurement system. To examine regulating mechanisms, we linked our results with other studies measuring root biomass with destructive sampling and root studies using minirhizotron techniques. Significantly higher soil CO2 evolution was observed in the elevated CO2 treatments in April and October; N effects were not significant. In October, integrated daily values for CO2 evolution rang ed from 3.73 to 15.68 g CO2•m−2•day−1 for the ambient CO2 + 0 N and 525 μL•L−1 CO2 + 20 g m−2 N, respectively. Soil CO2 flux among treatments was correlated with coarse root biomass (r2 = 0.40; p >F = 0.0380), indicating that at least some of the variation observed among treatments was related to variation in root respiration. Across all sample periods and treatments, there was a significant correlation (r2 = 0.63; p >F = 0.0001) between soil CO2 evolution and percent fungal hyphae observed in minirhizotron tubes. Hence, some of the seasonal and treatment variation was also related to differences in heterotrophic activity.
Effect of aluminum on the growth, anatomy, and nutrient content of ectomycorrhizal and nonmycorrhizal eastern white pine seedlings
Authors: Schier George A. , Mcquattie Carolyn J.
Published: October 2008

Effect of aluminum (Al) on the growth, anatomy, and nutrient content of eastern white pine (Pinusstrobus L.) was determined by growing newly germinated seedlings for 12 weeks in sand irrigated with nutrient solution (pH 3.8) containing 0, 12.5, 25, 50, 75, or 100 mg/L of Al. To determine the influence of mycorrhizal infection on Al toxicity, half of the seedlings were inoculated with the ectomycorrhizal fungus Pisolithustinctorius (Pers.) Coker & Couch. Across Al concentrations, shoot growth (height, needle length, biomass) but not root growth (lateral root length, biomass) was significantly greater in ectomycorrhizal (ECT) than nonmycorrhizal (NM) seedlings. Aluminum significantly decreased shoot and root growth in ECT and NM seedlings but had less effect on growth in ECT seedlings. Foliar symptoms of Al toxicity (chlorosis, tip necrosis) were more pronounced in NM than in ECT seedlings. Cellular and ultrastructural injury to needles and root meristematic tissues was observed at lower concentrations of Al in NM seedlings than in ECT seedlings. Amelioration of Al toxicity by mycorrhizal colonization appeared to result from enhanced uptake of nutrients, especially P, rather than to reduced uptake of Al.
Nutrient management in a Pinusradiata plantation after thinning: the effect of thinning and residues on nutrient distribution, mineral nitrogen fluxes, and extractable phosphorus
Authors: Carlyle J. Clive
Published: October 2008

The effects of thinning and residues on nutrient distribution, N fluxes, and extractable P were studied for 3 years after the first thinning of a 10-year-old Pinusradiata D. Don plantation. Treatments were (i) unthinned, (ii) thinned to 52% of basal area with all residues removed (zero residue; ZR), (iii) thinned with all residues retained and spread uniformly (normal residue; NR), and (iv) thinned with all residues retained plus the addition of those removed from the ZR treatment, approximately doubling the amount of residue in treatment NR (high residue; HR). The total nutrient contents of trees (above ground), residues, forest floor, and the top 0.30 m of mineral soil were 1206 kg N•ha−1, 126 kg P•ha−1, 828 kg K•ha−1, and 1272 kg Ca•ha−1 after thinning. Residues contained 11, 10, 10, and 7% of site N, P, K, and Ca, respectively. Thinning without residue retention (unthinned cf. ZR) elevated mean monthly maximum soil temperatures at a depth of 50 mm by up to 5.3 °C in summer and 1 °C in winter. Thinning had no effect on forest floor or mineral soil (0–0.30 m) moisture content. In the unthinned treatment an average of 25 kg N•ha−1•year−1 was mineralized, all of which was taken up by the trees, and there was no leaching. Thinning caused a 10% increase in rates of N mineralization and uptake and a small transient increase in soil mineral N concentrations, but had no effect on leaching. Maintenance of prethinning levels of N uptake by the remaining trees (after a 48% reduction in basal area) suggests that uptake per tree was approximately doubled. Maintenance of N uptake after thinning was consistent with maintenance of basal area growth (m2•ha−1) and an increase in foliar N concentrations. Thinning had no effect on extractable P in the forest floor or mineral soil. The retention of residues (NR and HR) decreased mean monthly maximum and elevated mean monthly minimum soil temperatures relative to the ZR treatment, and the effect increased with the amount of residue. Forest floor moisture content increased with the amount of residue, but residue retention had no effect on mineral soil moisture. Rates of mineralization were higher in the presence of residue and annual averages were 28, 33, and 42 kg N•ha−1•year−1 for ZR, NR, and HR treatments, respectively. Despite increased N mineralization in the presence of residue there was no leaching and all the additional N was taken up by the trees. Basal area increment increased in the presence of residue (P = 0.235) and was 10.7 (ZR), 11.1 (NR), and 11.8 (HR) m2•ha−1 over 4 years of measurement.
Relations entre des indicateurs de croissance du sapin baumier en début d'épidémie et sa vulnérabilité à la tordeuse des bourgeons de l'épinette
Authors: Thibault Denis , Bégin Jean , Bélanger Louis
Published: October 2008

Integrated pest management strategies for the spruce budworm (Choristoneurafumiferana (Clem.)) give high priority to preventive silvicultural treatments that increase the vigour of balsam fir stands to decrease their vulnerability. The aim of this study was to determine to which extent the survival probability of individual balsam firs (Abiesbalsamea L.), during the last budworm outbreak (1974–1986), was related to some growth rate indicators evaluated at the beginning of the outbreak. The study was carried out in two permanent study sites, established initially to follow the impact of precommercial thinnings on growth and yield in young boreal fir stands in eastern Quebec: the area of Lake Matapédia, thinned in 1968 and protected by chemical insecticides, and the area of Lake Huit-Milles, thinned in 1960 and not protected. Discriminant logistic models, based on tree diameters in 1976 and diameter growth rates between 1968 and 1976, were used to determine if it was possible to discriminate the state of the trees (living or dead) at the end of the outbreak. Using Dagnelie's transformation of the logistic model, we produced linear probability models that were called survival thresholds. In the protected study area (Lake Matapédia), the models correctly predicted the state of 81% of the individual trees in 1989 for the validation sample. In the unprotected stands (Lake Huit-Milles), we observed a higher position of the survival thresholds following higher defoliation levels. The relationship between tree growth indicators and tree vulnerability is stronger when defoliation levels are low to moderate, but is clearly weaker when defoliation is severe. At high levels of defoliation and without insecticide spraying programs, even vigourous trees become vulnerable.
Comparaison de différentes approches, modèles et tailles d'échantillons pour l'établissement de relations hauteur-diamètre locales
Authors: Bégin Jean , Raulier Frédéric
Published: October 2008

This study compares the predictability of 3 approaches, 4 models, and 10 different sample sizes to determine local relationships between total height and diameter at breast height in balsam fir stands less than 50 years old. The results show that a system of height–diameter curves based on the mean diameter and mean height of the sampled trees (approach 3) gives the most precise estimations in comparison with curves resulting from pooling all sampled trees in a single height–diameter model (approach 1) and with those resulting from the application of a height–diameter model for each of the combinations of sample plot–measurement periods (approach 2). Depending on the sample size, the residual variance of the total height or the total volume is reduced 2 to 2.5 times for the individual stems and 2 to 15 times for the mean stem, when using approach 3 instead of approach 1. Approach 3 is more precise than approach 2 for sample sizes that vary between three and five sampled trees per plot. However, this gain in precision becomes negligible when the sample size approaches 10 sampled trees per plot.
Acid-rain-induced changes in cuticles and Ca distribution in Scots pine and Norway spruce seedlings
Authors: Turunen Minna , Huttunen Satu , Back Jaana , Lamppu Jukka
Published: October 2008

Seedlings of Scots pine (Pinussylvestris L.) and Norway spruce (Piceaabies (L.) Karst.) were subjected to acid rain irrigation at pH 7, pH 4, and pH 3 three times a week during the growing seasons of 1986–1989 in a field experiment. Scanning and transmission electron microscopy, energy dispersive spectrometry, contact angle measurements, and chloroform extraction of waxes were used to detect physicochemical changes in the needle cuticles. The first detectable symptoms of acid rain were observed after 5 weeks of acid rain treatment at pH 3 and pH 4, which resulted in few CaSO4 crystallites on visibly undamaged pine and spruce needle surfaces. After 7 weeks of acid rain treatment there were CaSO4 crystallites scattered over the whole needle surface area and erosion of the epicuticular waxes could be observed occasionally. CaSO4 crystal formation later decreased, especially on the needles of seedlings treated at pH 3. Ca concentrations in the needles and roots of the seedlings and in the soil in the boxes were higher in the pH 3 treatments than elsewhere. The more abundant deposition of Ca oxalate crystallites on the inner walls of the epidermal and hypodermal cells of the spruce needles than on their outer walls was probably also connected with Ca leaching, caused by acid rain. Acid rain also delayed wax synthesis, as 2-month-old pine needles exposed to pH 3 and pH 4 had about 50% less wax than the water controls in early August. The needle surfaces of the southern provenances of spruce and pine seedlings were slightly less wettable after pH 4 treatment than after the control water treatment, because they probably benefited from N and S compounds in the irrigation water. The needle surfaces were more wettable in the pH 3 and water control seedlings than in the other treatments.
Spatial variation in tree regeneration in the forest-tundra ecotone, Rocky Mountain National Park, Colorado
Authors: Weisberg Peter J. , Baker William L.
Published: October 2008

Ecotone vegetation may be especially sensitive to climate change. In particular, the invasion of subalpine meadows by tree seedlings has been well documented. However, there has been no systematic analysis of tree regeneration across the environmental heterogeneity of the alpine forest–tundra ecotone (FTE). Also, the position of the FTE may be relictual from more favorable climates of the past and therefore unresponsive to changing climate. To assess the environmental controls on FTE tree regeneration, to determine whether the ecotone might be relictual, and to determine whether tree invasion of nonforested FTE areas is occurring, we measured tree regeneration in various environments within the FTE of Rocky Mountain National Park, Colorado. Generally, seedling establishment appears to be controlled by patterns of soil moisture. Little seedling establishment was observed in krummholz openings, except for high seedling densities in willow wetlands. Tree seedling invasion of tundra is rare. Therefore, the upper limits of the FTE in Rocky Mountain National Park may be relictual from more favorable climates of the past. Abundant seedling establishment in patch forest openings suggests that patch forest may be poised to change to closed forest.
Tomato mosaic virus infection of red spruce on Whiteface Mountain, New York: prevalence and potential impact
Authors: Castello John D. , Bachand George D. , Wargo Philip M. , Jacobi Volker , Tobi Donald R. , Rogers Mary A.M.
Published: October 2008

Tomato mosaic tobamovirus (ToMV) was detected by enzyme-linked immunosorbent assay in the roots of red spruce (Picearubens Sarg.) on Whiteface Mountain, New York. Both virus incidence and concentration in the roots of red spruce vary by site and were greater in trees with little to moderate crown dieback than in trees with severe dieback. There was no significant association between virus incidence or concentration in the roots of red spruce and elevation on Whiteface Mountain. Multiple regression analysis of virus concentration in the roots, as the dependent variable, was performed against nine selected crown and root variables. In the final regression model, the number of live second-order nonwoody roots per length of first-order nonwoody root and length of the live crown were positively and negatively correlated, respectively, with virus concentration in the roots. These results suggest a complex epidemiology and a potentially significant impact of ToMV infection on the growth of red spruce on Whiteface Mountain.
Soil nitrogen status 8 years after whole-tree clear-cutting
Authors: Johnson Chris E.
Published: October 2008

Previous research on chronosequences of even-aged northern hardwood stands has suggested that forest clearing is accompanied by large losses of nitrogen from the forest floor. The timing of the losses and the fate of a large fraction of the lost nitrogen are unclear. The purpose of this investigation was to study these questions through direct measurement of soil nitrogen concentrations and pools through time on an experimental catchment cleared in a whole-tree harvest in 1983–1984. Nitrogen losses from the forest floor at the site, the Hubbard Brook Experimental Forest, New Hampshire, were lower than predictions based on previous research. The mean forest floor nitrogen pool was 17% lower 8 years after clear-cutting of the site (P = 0.18). Predictions based on chronosequence studies suggest that 25–40% of the forest floor nitrogen would be lost after 8 years. Mechanical disturbance during logging may play a role in limiting short-term nitrogen losses. The steep midsection of the catchment experienced the greatest losses of nitrogen and carbon, while pools in the relatively flat spruce-fir zone at the upper elevations were unchanged. Carbon was preferentially lost from soil organic matter, relative to nitrogen, resulting in significant decreases in the C/N and C/organic matter ratios in the soil. The N/organic matter ratio was generally unchanged. Nitrogen losses can be limited after clear-cutting by minimizing organic matter losses and promoting rapid regrowth.
Field performance of outplanted Norway spruce: effects of organic matter amendments and site preparation
Authors: Hallsby Goran
Published: October 2008

Norway spruce (Piceaabies (L.) Karst.) seedling survival and growth response to site preparation methods involving different utilization of humus (forest floor material from the F- and H-layers) and chipped slash were studied on a recently clear-felled spruce site in northern Sweden. Five mounding treatments (pure mineral soil, mineral mound covered by or mixed with either of the two types of organic matter) and two unscarified treatments (with or without a chipped slash mulch) were applied in a randomized block design. Half of the blocks were planted in the year of clear-felling (1990) and the remaining blocks in 1991. Containerized (1/0) seedlings mechanically protected against Hylobiusabietis L. were used. For both planting occasions, seedling survival after 3 years exceeded 90% in most treatments and the occurrence of injuries was significantly (p < 0.05) affected by soil treatments only in the 1990 plantation. In general, the largest seedlings (height, dry weight, needle weight, needle length, leading shoot terminal bud diameter) developed in mounds containing humus, and mounds containing chipped slash produced the smallest seedlings. Mixing chipped slash with mineral soil appeared to suppress seedling growth. The results also indicate that planting delay should be avoided to permit Norway spruce seedlings to benefit fully from the growth-stimulating potential of humus. Successful planting without site preparation might depend on the avoidance of planting delay.