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PubMed2006

Trees as reservoirs for amphibole fibers in Libby, Montana.

Tree bark and core samples were collected from areas surrounding the asbestos-contaminated vermiculite mine in Libby, MT. These samples were collected to provide preliminary data in support of a proposed study to determine if trees can serve as reservoirs for amphibole fibers and to determine if there is a potential for exposure to those that harvest contaminated wood in the Libby mine area, specifically during firewood harvesting and commercial logging. Initially, three sets of samples were taken both within and directly outside of the EPA restricted area surrounding the mine site. Based on the results of the initial samples, a follow-up sampling program was conducted both in the town of Libby and directly outside the city limits. Gravimetric reduction of a tree core sample did not indicate the presence of amphibole fibers. However, transmission electron microscopy analysis of bark samples collected near the vermiculite mine yielded substantial amphibole fiber concentrations ranging from 41 million to 530 million fibers/g of bark. In addition, a bark sample collected approximately 7 miles west of the town next to a railroad line had concentrations of 19 million fibers/g. A conversion of these mass-based concentrations to areal concentrations (to reflect surface area contamination) revealed concentrations in excess of 100 million amphibole fibers/cm(2). These preliminary results suggest that trees in the Libby valley and along vermiculite shipping corridors can serve as reservoirs for amphibole fibers, and that a potential for exposure exists for those who harvest contaminated wood.

Asbestos, Amphibole↗
PubMed2006

The use of compost in afforestation of Mediterranean areas: Effects on soil properties and young tree seedlings.

In Mediterranean frequently burnt areas, fire and erosion result in the decrease of soil fertility, so afforestation is a major concern. We carried out an in situ experiment of compost amendment to improve survival and growth of planted tree seedlings. One-year-tree seedlings of native species (Quercus ilex, Pinus halepensis and Pinus pinea) were planted on a frequently burnt calcareous site. Three rates of fresh co-composted sewage sludge and greenwastes (control without compost, 20 and 40 kg m(-2) of compost) were incorporated into the soil at each seedling stem. Changes of soil properties and tree development were studied during 3 years (2001-2003) and 2 years (2002-2003) respectively. The compost improved survival of Quercus ilex and Pinus pinea seedlings in severe drought conditions, but had no effect on Pinus halepensis. For all species seedling length and radial growth and NPK nutrition were increased for both rates of amendment. Amendment improved soil fertility, but available P concentration increased 13 fold in the neighbouring soil of seedlings amended at the maximal rate compared to control. However, amendment did not significantly increase concentrations of Cd, Cr, Ni and Pb in soils or tree seedlings. It increased Cu and Zn total and available concentrations in soils, while foliar Cu and Zn concentrations in the seedlings remained similar in all plots. Compost can efficiently help afforestation of dry soils with low organic matter content. However, sewage sludge concentrations in P, and to a lesser extent in Cu and Zn, limit rates of application that can be applied without environmental hazard.

Agriculture↗
PubMed2005

Ultrasonic techniques for nondestructive testing of standing trees.

The aim of this study is to assess wood quality of standing trees with ultrasonic velocity methods. The ultrasonic techniques currently used are: scattering based techniques that use travel time and other wave parameters for measuring the elastic constants of wood, and ultrasonic tomographic imaging techniques which seek to provide a high resolution picture of the defect. Scattering based techniques were firstly used as nondestructive techniques with increment cores of 5 mm diameter. On these specimens measurements with bulk waves--longitudinal and shear were used to detect the influence of sylvicultural treatment (pruning) on wood quality and also to detect defects (slope of grain, wavy figures). High resolution imaging techniques were developed for imaging abnormalities induced by biological attacks of fungi or insects in standing trees. In this case, ultrasonic tomography refers to cross-sectional imaging of trees from data collected by illuminating the tree from different directions. Ultrasonic images were reconstructed from the time of flight. The images were reconstructed from 120 measurements in situ and through the bark with direct transmission technique, using 1 MHz transducers. The resolution is 5 cm.

Animals↗
PubMed2003

Cost-effective treatment for ureteropelvic junction obstruction: a decision tree analysis.

PURPOSE: We determined the optimal treatment for primary ureteropelvic junction obstruction based on cost using a decision tree model. MATERIALS AND METHODS: A comprehensive literature search for articles addressing surgical correction of ureteropelvic junction obstruction was performed and data were abstracted on operative time, hospital stay, complications and success rate. The overall cost and individual cost centers at our institution for antegrade endopyelotomy, retrograde ureteroscopic endopyelotomy, Acucise (Applied Medical Resources, Laguna Hills, California) endopyelotomy, laparoscopic pyeloplasty and open pyeloplasty were compared. A decision tree model estimated the cost of treatment and followup for each modality using commercially available software. Sensitivity analyses were performed to evaluate the effect of individual treatment variables on overall cost. RESULTS: Based on cost center review retrograde ureteroscopic endopyelotomy was the least costly procedure ($2,891). In the decision tree model the rank order of overall treatment costs was: retrograde ureteroscopic endopyelotomy ($3,842), Acucise endopyelotomy ($4,427), antegrade endopyelotomy ($5,297), laparoscopic pyeloplasty ($7,026) and open pyeloplasty ($7,119). Despite various hospital stay, operative time, equipment cost and success rate data 1-way sensitivity analysis revealed that antegrade endopyelotomy, laparoscopic pyeloplasty and open pyeloplasty were never cost effective compared with retrograde ureteroscopic endopyelotomy or Acucise endopyelotomy, while 2-way sensitivity analysis favored retrograde ureteroscopic endopyelotomy. CONCLUSIONS: Primary cost variables for ureteropelvic junction obstruction treatments include operative time, hospital stay, equipment cost and success rate. Decision tree analysis showed that retrograde ureteroscopic or Acucise endopyelotomy is the most cost-effective treatment modality at our institution. However, cost is only 1 of a number of factors that are considered when deciding on an optimal course of treatment.

Cost-Benefit Analysis↗
PubMed2003

Effect of global climate change and human disturbances on tree diversity of the forest regenerating from clear-cuts of mixed broadleaved Korean pine forest in Northeast China.

Studies on the combined effects of global climate change and human disturbances are important for biodiversity conservation and natural resources management. Here we use the modified forest dynamics model to simulate the tree diversity change of a typical mixed broadleaved Korean pine forest regenerating from clear-cuts in Northeast China in response to global climate change, double concentration of CO(2) and human disturbances during the next 50 years. We consider the following climate change scenario: the annual temperature will increase 2 degrees C, the annual precipitation will increase 10% and CO(2) concentration will increase to 700 microll(-1) linearly in 50 years. Five kinds of human disturbances under climate change are considered: logging which removes all trees with diameter at the breast height of more than 50 cm; removing all individuals of any one species; and removing all individuals of shade tolerant, shade intolerant and medium type tree species, respectively. We find that the index of proportional representation of species (alpha index) for the forest growing from clear-cuts increases significantly under climate change, but decreases under climate change plus logging. The index of changing representation of species (beta(c) index) increases significantly under climate change and climate change plus logging. When any one species is removed alpha diversity of the forest growing from clear-cuts changes significantly under climate change, but beta(c) index remains almost the same. When all individuals of shade tolerant species, shade intolerant species, or medium type species are removed, respectively, alpha diversity decreases, but beta(c) diversity changes in more complicated ways. The implications of these results for preserving tree diversity in this type of forest are also discussed.

China↗
PubMed2002

Mercury levels in lichens from different host trees around a chlor-alkali plant in New Brunswick, Canada.

Mercury concentrations were determined in the epiphytic lichen Hypogymnia physodes along five transects starting from a chlor-alkali plant located at Dalhousie, New Brunswick, a landfill site and a nearby electricity generating station. Lichen samples were collected from white birch (Betula papyrifera) and spruce (Picea sp.) or balsam fir (Abies balsamea). Average lichen background mercury values were 0.088+/-0.005 microg/g from white birch and 0.148+/-0.046 microg/g from spruce trees, with a detection limit of 0.05 microg/g. The chlor-alkali plant and a power plant were identified, respectively, as a major source and a minor source of elevated mercury levels in lichens. At 125 m north-west of the New Brunswick Power plant, 0.28 microg/g Hg were found in Hypogymnia physodes from spruce trees, while at 250 m west (downwind) of the chlor-alkali plant, 3.66 microg/g of mercury were determined. High values, 0.98 microg/g in lichens from spruce trees and 0.79 microg/g in lichen samples from white birch were also measured at 125 m south of the chlor-alkali plant and decreased exponentially with distance. The sphere of influence of the chlor-alkali plant with respect to mercury deposition was estimated to extend 2.4-3.4 km from the plant. The mercury concentrations in Hypogymnia physodes collected from white birch were significantly lower than the concentrations in the same lichen from spruce trees in areas with elevated levels of mercury, but not in areas with low mercury levels. The magnitude of this difference dropped with distance from the source.

Air Pollutants↗
PubMed2001

Recent advances in the genetic transformation of trees.

As the commercial production of transgenic annual crops becomes a reality in many parts of the world, many people wonder if the genetic engineering of perennial trees will allow their eventual commercialization. Not long ago, trees were considered to be recalcitrant material for most molecular biology techniques, including genetic transformation. However, transgenes for shortening the juvenile phase or for phytoremediation purposes have now been incorporated, and the alteration of lignin biosynthesis and increased cellulose accumulation in forest trees have also been accomplished. For long-lived tree species, new questions arise regarding the stability of integration and expression of foreign genes. Biosafety considerations, including transgene dispersion through the pollen and advances in strategies to avoid this, are also important.

Biodegradation, Environmental↗
PubMed2001

Spectral shade ratios on horizontal and sun normal surfaces for single trees and relatively cloud free sky.

Spectral shade ratios, defined as the ratios of the spectral irradiances on horizontal and sun normal planes in the tree shade to those on a horizontal plane in sunlight, were calculated. These planes were in the shade of an isolated medium canopy density tree and a sparse canopy density tree at the tree shade sites of the centre, edge and trunk. The sun normal plane was employed as there are some activities that have exposures to parts of the body that are orientated in a sun normal plane. The horizontal plane shade ratios for the medium density canopy dropped by 47-56% from the ratios in the range 301 to 310 nm to the ratios in the range 391 to 400 nm. In absolute terms, the largest change in the shade ratio of 0.28 was for the centre and edge sites compared to 0.07 for the trunk. Similarly, for the sun normal plane, the ratio dropped by 40-49% with an absolute reduction of 0.19 for the edge and 0.04 for the trunk. For the sparse density canopy, the decrease in the shade ratios over the same wavelength range was a drop by 37-42% on a horizontal plane or, in absolute terms, a reduction by 0.22 for the edge and 0.13 for the trunk. Similarly, the decrease was 34-39% on the sun normal plane or, in absolute terms, a reduction by 0.19 for the edge and 0.12 for the trunk.

Spectrophotometry, Ultraviolet↗
PubMed2002

Why do trees live so long?

A long life multiplies a tree's reproductive opportunities, thus increasing its fitness. Therefore, characteristics that prolong life should be naturally selected. Longevity in trees is achieved by means of numerous behaviors and characteristics, some of which are unique to trees. These include the retention of stem-cell-like meristematic cells after each growth cycle; the ability to replace non-vigorous, lost, or damaged organs, both above and below ground, in the presence or absence of trauma; a sectored vascular system that allows part of a tree to survive where a whole one cannot; formation of clones; a mechanical structure that can react to forces tending to de-optimize it; a hormonal control system that coordinates the above behaviors; and synthesis of defensive compounds.

Environment↗
PubMedDate not supplied

Genetic programming for the induction of decision trees to model ecotoxicity data.

Automatic induction of decision trees and production rules from data to develop structure-activity models for toxicity prediction has recently received much attention, and the majority of methodologies reported in the literature are based upon recursive partitioning employing greedy searches to choose the best splitting attribute and value at each node. These approaches can be successful; however, the greedy search will necessarily miss regions of the search space. Recent literature has demonstrated the applicability of genetic programming to decision tree induction to overcome this problem. This paper presents a variant of this novel approach, using fewer mutation options and a simpler fitness function, demonstrating its utility in inducing decision trees for ecotoxicity data, via a case study of two data sets giving improved accuracy and generalization ability over a popular decision tree inducer.

Algorithms↗
PubMed2003

Accurate estimation of forest carbon stocks by 3-D remote sensing of individual trees.

Forests are one of the most important carbon sinks on Earth. However, owing to the complex structure, variable geography, and large area of forests, accurate estimation of forest carbon stocks is still a challenge for both site surveying and remote sensing. For these reasons, the Kyoto Protocol requires the establishment of methodologies for estimating the carbon stocks of forests (Kyoto Protocol, Article 5). A possible solution to this challenge is to remotely measure the carbon stocks of every tree in an entire forest. Here, we present a methodology for estimating carbon stocks of a Japanese cedar forest by using a high-resolution, helicopter-borne 3-dimensional (3-D) scanning lidar system that measures the 3-D canopy structure of every tree in a forest. Results show that a digital image (10-cm mesh) of woody canopy can be acquired. The treetop can be detected automatically with a reasonable accuracy. The absolute error ranges for tree height measurements are within 42 cm. Allometric relationships of height to carbon stocks then permit estimation of total carbon storage by measurement of carbon stocks of every tree. Thus, we suggest that our methodology can be used to accurately estimate the carbon stocks of Japanese cedar forests at a stand scale. Periodic measurements will reveal changes in forest carbon stocks.

Automation↗
PubMed2006

Brominated flame retardants in tree bark from North America.

Brominated flame retardants were measured in 87 tree bark samples from 29 locations in North America. The concentrations of total polybrominated diphenyl ethers (PBDEs) ranged from 2.3 to 5700 ng/g lipid weight, with the highest concentrations found near or in Arkansas. A simple radial dilution model nicely describes the distribution of total PBDE concentrations in these samples and indicates the likely sources ofthese chemicals are emissions from the two brominated flame retardant manufacturing facilities, operated by Great Lakes Chemicals and Albemarle, located in southern Arkansas. The congener profiles of PBDEs are similar for all the tree bark samples and can be described by a mixture of the congener profiles of the penta- and deca-BDE commercial products combined in a ratio of 1:2. Two unusual BFRs, 1,2-bis(2,4,6-tribromophenoxy)ethane and decabromodiphenyl ethane, were also detected in tree bark samples collected in Arkansas, suggesting the two manufacturing facilities are the sources of these compounds as well. A polybrominated biphenyl congener (BB-153) was present in most tree bark samples at low levels relative to the PBDEs.

Air Pollutants↗
PubMed2006

Isotopic evidence in tree rings for historical changes in atmospheric sulfur sources.

Little is understood about the usefulness of sulfur isotopic ratios (sigma 34S) in tree rings because the sulfur content in rings is generally insufficient for analysis using conventional methods. We present sigma 34S values of the water-soluble and the organically bound sulfur fractions in rings of coniferous trees grown in Japan, analyzed using a large-volume oxygen bomb. Comparing the sigma 34S values of the organically bound fraction in tree rings with past atmospheric sulfur concentrations and with those of their sources, we find clear evidence that the sigma 34S values of the organically bound fraction in the rings are dependent upon the values of the atmospheric sulfur sources. The evidence suggests that the sigma 34S values in tree rings are a useful chronological proxy for evaluating possible causes of past atmospheric sulfur pollution.

Air Pollutants↗
PubMed2006

Application of an enzyme-linked immunosorbent assay for the analysis of imidacloprid in wiliwili tree, Erythrina sandwicensis O. Deg, for control of the wasp Quadrastichus erythrinae.

A monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) for the neonicotinoid insecticide imidacloprid was evaluated for its reproducibility, accuracy, and comparability to results from a conventional high-performance liquid chromatography (HPLC) for the analysis of imidacloprid in the endemic wiliwili tree (Erythrina sandwicensis O. Deg) found in dryland forests and landscapes in Hawaii. Imidacloprid was applied to these wiliwili trees in an attempt to control the newly introduced erythrina gall wasp, Quadrastichus erythrinae Kim. Leaf samples were freeze-dried and extracted with acidic aqueous methanol followed by methylene chloride partitioning. After solvent removal, the extract residue was reconstituted in 1 mL of water/methanol (1:1, v/v) for ELISA; no significant matrix interference was observed at 10-fold or more dilution. The average recoveries of imidacloprid from fortified samples ranged from 78% to 100% by ELISA. The correlation between the ELISA and HPLC results was excellent (r2 = 0.98). Imidacloprid was detected with the ELISA in all treated samples and its level varied in the samples among different treatments and in those from different parts of the trees. The infestation severity rating of leaf samples was inversely related to the concentration of imidacloprid. It is clear that imidacloprid effectively controls the wasps. The ELISA is a suitable method for quantitative and reliable determination of imidacloprid in wiliwili trees and the application provides information to understand how to control the wasps.

Chromatography, High Pressure Liquid↗
PubMed2000

The art of building decision trees.

Decision support systems that help physicians are becoming a very important part of medical decision making. They are based on different models and the best of them are providing an explanation together with an accurate, reliable, and quick response. One of the most viable among models are decision trees, already successfully used for many medical decision-making purposes. Although effective and reliable, the traditional decision tree construction approach still contains several deficiencies. Therefore we decided to develop and compare several decision support models using four different approaches. We took statistical analysis, a MtDeciT, in our laboratory developed tool for building decision trees with a classical method, the well-known C5.0 tool and a self-adapting evolutionary decision support model that uses evolutionary principles for the induction of decision trees. Several solutions were evolved for the classification of metabolic and respiratory acidosis (MRA). A comparison between developed models and obtained results has shown that our approach can be considered as a good choice for different kinds of real-world medical decision making.

Acidosis, Respiratory↗
PubMed2003

Novel gene expression profiles define the metabolic and physiological processes characteristic of wood and its extractive formation in a hardwood tree species, Robinia pseudoacacia.

Wood is of critical importance to humans as a primary feedstock for biofuel, fiber, solid wood products, and various natural compounds including pharmaceuticals. The trunk wood of most tree species has two distinctly different regions: sapwood and heartwood. In addition to the major constituents, wood contains extraneous chemicals that can be removed by extraction with various solvents. The composition and the content of the extractives vary depending on such factors as, species, growth conditions, and time of year when the tree is cut. Despite the great commercial and keen scientific interest, little is known about the tree-specific biology of the formation of heartwood and its extractives. In order to gain insight on the molecular regulations of heartwood and its extractive formation, we carried out global examination of gene expression profiles across the trunk wood of black locust (Robinia pseudoacacia L.) trees. Of the 2,915 expressed sequenced tags (ESTs) that were generated and analyzed in the current study, 55.3% showed no match to known sequences. Cluster analysis of the ESTs identified a total of 2278 unigene sets, which were used to construct cDNA microarrays. Microarray hybridization analyses were then performed to survey the changes in gene expression profiles of trunk wood. The gene expression profiles of wood formation differ according to the region of trunk wood sampled, with highly expressed genes defining the metabolic and physiological processes characteristic of each region. For example, the gene encoding sugar transport had the highest expression in the sapwood, while the structural genes for flavonoid biosynthesis were up-regulated in the sapwood-heartwood transition zone. This analysis also established the expression patterns of 341 previously unknown genes.

DNA, Complementary↗
PubMed2002

Antifungal effect of Australian tea tree oil on Malassezia pachydermatis isolated from canines suffering from cutaneous skin disease.

The lipophilic yeast Malassezia pachydermatis is part of the normal skin flora of most warm-blooded organisms. In a number of surveys it could be demonstrated that this yeast species might be involved in different skin diseases like seborrhoeic dermatitis, especially in dogs and cats. In order to look for an alternative therapeutic agent to the commonly used antimycotic and antiseptic synthetic substances the in vitro activity of Australian tea tree oil, the essential oil of Melaleuca alternifolia, against several strains of Malassezia pachydermatis was examined. All tested strains showed remarkably high susceptibility to tea tree oil. With these results the excellent antibacterial activity of tea tree oil is extended to a new group of fungal pathogens colonizing mainly mammals' skin. During the last ten years there was an increasing popularity of tea tree oil containing human health care products. The presented data open up new horizons for this essential oil as a promising alternative agent for topical use in veterinary medicine as well.

Animals↗
PubMed2002

Phytotherapy of chronic dermatitis and pruritus of dogs with a topical preparation containing tea tree oil (Bogaskin).

Localised dermatitis, for example unspecific eczema or skinfold pyoderma, is a very common diagnosis in dogs. Typical and impressive complaints are pruritus, erythema, erosion and oozing surface. With respect to the underlying disease dermatological treatment is indicated, usually based on antimicrobial and antipruriginous active substances, it can include transient glucocorticoids. An effective and safe alternative might be a phytotherapeutic topical preparation containing tea tree oil. Tea tree oil exerts both antimicrobial and antipruriginous effects. In an open multicenter study efficacy and safety of a standardized 10% tea tree oil cream applied thinly and twice daily for 4 weeks was tested in 53 dogs with chronic dermatitis, particularly non-specific eczema, allergic dermatitis, interdigital pyoderma, acral lick dermatitis and skinfold pyoderma. Analysis of efficacy assessed by investigating veterinarians showed a good or very good response to treatment for 82% of the dogs, significant at a 5% level (p = 0.05). At the end of the study a strong and significant reduction (p = 0.001) as well as disappearance of major symptoms were observed. Only two adverse events (local reactions) possibly related to tea tree oil occurred during therapy. Consequently the tested study medication (Bogaskin) can be considered an alternative for uncomplicated and localised dermatitis in dogs. Bogaskin might allow reduction of other pharmaceutical products, perhaps even replace standard therapy.

Administration, Topical↗