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PubMed2004

Techniques for accuracy assessment of tree locations extracted from remotely sensed imagery.

Remotely sensed imagery is becoming a common source of environmental data. Consequently, there is an increasing need for tools to assess the accuracy and information content of such data. Particularly when the spatial resolution of imagery is fine, the accuracy of image processing is determined by comparisons with field data. However, the nature of error is more difficult to assess. In this paper we describe a set of tools intended for such an assessment when tree objects are extracted and field data are available for comparison. These techniques are demonstrated on individual tree locations extracted from an IKONOS image via local maximum filtering. The locations of the extracted trees are compared with field data to determine the number of found and missed trees. Aspatial and spatial (Voronoi) analysis methods are used to examine the nature of errors by searching for trends in characteristics of found and missed trees. As well, analysis is conducted to assess the information content of found trees.

Automation↗

PubMed2004

Self-organization of tree form: a model for complex social systems.

The branches of a tree can be viewed as redundant organs: they have the same functional roles and the same unlimited developmental potential. The most prominent aspect of tree form, here considered as an example of dynamic self-organization, is the relations among these branches. A branch is a source of information about its size, state and environment. A response to this information is the oriented vascular differentiation which connects the branch with the rest of the plant. A known phytohormone, auxin, is formed by shoot tissues and replaces this orienting influence of a shoot. This accounts for neighboring branches having specific, even competing, effects without any other branch specificity. The same phytohormone also elicits different processes throughout the plant, integrating their occurrence without recourse to a central control. Self-organization requires a positive feedback that enhances the development of a successful branch, and an inhibitory influence that reduces similar branch growth. Both roles could depend on the oriented vascular differentiation that is specified by auxin. Actual tree form at any given time is a transient dynamic state. One reason for this is that competition between branches is a long-term, gradual process. A second reason is that a periodic surfeit of root supplies enhances a seasonal formation of many branches which 'search' environmental possibilities, and most of these branches decline only gradually. The various aspects of tree form could thus depend on remarkably simple and robust principles, requiring only limited genetic information. Much of the necessary information about the details of tree form is generated by a Darwinian-like process of developmental selection, reaching a predictable overall outcome without following any strict plan. It is a case of self-organization in which the component structures, the tree branches, do not move, but do undergo long term developmental changes.

Animals↗

PubMed2006

An analytical model of stand dynamics as a function of tree growth, mortality and recruitment: the shade tolerance-stand structure hypothesis revisited.

Light competition and interspecific differences in shade tolerance are considered key determinants of forest stand structure and dynamics. Specifically two main stand diameter distribution types as a function of shade tolerance have been proposed based on empirical observations. All-aged stands of shade tolerant species tend to have steeply descending, monotonic diameter distributions (inverse J-shaped curves). Shade intolerant species in contrast typically exhibit normal (unimodal) tree diameter distributions due to high mortality rates of smaller suppressed trees. In this study we explore the generality of this hypothesis which implies a causal relationship between light competition or shade tolerance and stand structure. For this purpose we formulate a partial differential equation system of stand dynamics as a function of individual tree growth, recruitment and mortality which allows us to explore possible individual-based mechanisms--e.g. light competition-underlying observed patterns of stand structure--e.g. unimodal or inverse J-shaped equilibrium diameter curves. We find that contrary to expectations interspecific differences in growth patterns can result alone in any of the two diameter distributions types observed in the field. In particular, slow growing species can present unimodal equilibrium curves even in the absence of light competition. Moreover, light competition and shade intolerance evaluated both at the tree growth and mortality stages did not have a significant impact on stand structure that tended to converge systematically towards an inverse J-shaped curves for most tree growth scenarios. Realistic transient stand dynamics for even aged stands of shade intolerant species (unimodal curves) were only obtained when recruitment was completely suppressed, providing further evidence on the critical role played by juvenile stages of tree development (e.g. the sampling stage) on final forest structure and composition. The results also point out the relevance of partial differential equations systems as a tool for exploring the individual-level mechanisms underpinning forest structure, particularly in relation to more complex forest simulation models that are more difficult to analyze and to interpret from a biological point of view.

Computer Simulation↗

PubMed2002

Historical changes in lead concentrations in tree-rings of sycamore, oak and Scots pine in north-west England.

Lead concentrations in tree rings of sycamore (Acer pseudoplatanus L.), oak (Quercus robur L.) and Scots pine (Pinus sylvestris L.) sampled at a parkland in north-west England were measured in wood formed since the mid-1800s. Concentrations of Pb in Scots pine and oak peaked in wood formed between 1900 and 1940, most likely because of Pb accumulation in heartwood, indicating that oak and Scots pine are unsuitable for monitoring temporal changes in Pb deposition at the study site. In contrast, Pb concentrations in sycamore, a species that has similar heartwood and sapwood chemistry, were relatively constant in wood formed between the mid-1800s and 1950. Lead concentrations decreased steadily in sycamore tree rings formed after the 1950s, and decreased more abruptly in wood formed after 1985. This sharp decrease in wood Pb cannot be due to decreases in soil Pb concentration. Stable Pb isotope analysis was used to further investigate Pb patterns in sycamore wood. Excess 206Pb/207Pb ratios in tree-rings of sycamore were relatively constant, approximately 1.17, in wood formed prior to the 1930s, but decreased steadily thereafter reaching a minimum value of approximately 1.16 in wood formed between 1975 and 1985 after which time 206Pb/207Pb ratios increased. This pattern is consistent with changes in Pb isotope ratios measured in peat, sediment and aerosol samples in the UK. However, the magnitude of the decrease in 206Pb/207Pb (largely due to gasoline Pb) is considerably lower than in other studies and our estimates indicate that less than 20% of the total Pb in sycamore wood measured since the mid-1800s is derived from gasoline emissions. A more likely explanation for the pattern of Pb observed in sycamore tree rings is that soil Pb accumulates within rings of the diffuse porous wood over a number of years. Such uptake patterns would result in lower Pb concentrations in the outer (more recently formed) tree rings, which coincide with recent reductions in Pb deposition in the UK. Overall, this study indicates that tree ring chemistry is unsuitable for monitoring historical changes in Pb deposition at the study site.

Air Pollutants↗

PubMed2003

Plant self-defense mechanisms against oxidative injury and protection of the forest by planting trees of triploids and tetraploids.

The depletion of the ozone layer, and the resulting substantial increase in incident ultraviolet (UV) irradiation and subsequent oxygen radical formation on the Earth, have caused an extensive variety of damage to the world's forests. Superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px), which scavenge harmful oxygen radicals and inhibit lipid peroxides, were examined in two types of Japanese cedars, black pines, and cypresses, namely those with leaves showing premature withering, shedding, or dying and those with leaves not showing these effects prematurely. The effect of homogenates from these trees on lipid peroxide formation in a reaction system which UV light induces was also studied. The results indicate that strong black pines have significantly higher SOD activities than ordinary black pines, the leaves of which prematurely wither or die. Remarkably, trees that had triploid or tetraploid chromosomes showed higher SOD levels than diploid trees and markedly inhibited lipid peroxide formation since the SOD gene resides on a chromosome. This was especially true of plus trees of Japanese cypress, some of which had five times higher SOD activities than common Japanese cypresses although GSH-Px appears to play less of a role in this regard. Rice leaves and osmunda which are resistant to UV damage showed markedly higher SOD and GSH-Px activity. Our experiments suggest that the trees that have high SOD can protect themselves by scavenging oxygen radicals induced by UV irradiation and inhibit harmful lipid peroxide formation. In order to protect forests from oxidative damage by UV light, we should plant trees of natural mutants and artificially crossed triploids and tetraploids.

Adaptation, Physiological↗

PubMed2004

Staphylococcus aureus and wounds: a review of tea tree oil as a promising antimicrobial.

Antibiotic-resistant bacteria continue to be a major health concern worldwide. In particular, Staphylococcus aureus, both methicillin-resistant and -sensitive, are of concern in their ability to cause difficult skin and underlying tissue infections. Melaleuca alternifolia oil (tea tree oil), an essential oil, has demonstrated promising efficacy in treating these infections. Tea tree oil has been used for centuries as a botanical medicine, and has only in recent decades surfaced in the scientific literature as a promising adjunctive wound treatment. Tea tree oil is antimicrobial, anti-inflammatory, and has demonstrated ability to activate monocytes. There are few apparent side effects to using tea tree oil topically in low concentrations, with contact dermatitis being the most common. Tea tree oil has been effective as an adjunctive therapy in treating osteomyelitis and infected chronic wounds in case studies and small clinical trials. There is a need for larger clinical trials to further examine efficacy of tea tree oil as an adjunctive wound therapy, as well as improved guidelines for developing plant-based medicines.

Anti-Infective Agents, Local↗

PubMed2001

The influence of the development of temperate fruit tree species on the potential for their uptake of radionuclides.

This paper reviews the published literature that describes the phenological development of above and below ground organs of temperate fruit trees (top fruit), particularly with respect to apple (Malus domestica). Critical information is presented which is considered appropriate in developing an understanding of the potential for top fruit species to take up radionuclide contaminants from the atmosphere and the soil. Information is cited on how climatic and edaphic factors influence the growth and development of temperate fruit trees, the phenological production of their leaf area and the development and growth of their fruit and hence the potential for foliar and fruit uptake of radionuclides from the atmosphere. The study also reports on the importance of the distribution and phenological development of roots in the soil and the potential for their uptake of radionuclides from the soil. The effects of above and below ground management procedures, within temperate fruit orchards, on potential radionuclide uptake are also considered. It is concluded that the potential for the uptake of radionuclides by temperate fruit tree species will depend on a number of phenological and physiological factors. For uptake from the soil these factors include; root distribution and density in the soil profile, seasonal changes in the production and distribution of roots, and the presence and amount of water in the soil. These factors are themselves influenced by rootstock type and its growth vigour, scion type and its growth vigour, tree age, spacing of trees in the orchard, orchard management practices (presence or absence of weeds or grass under the trees) and soil type and depth. Direct uptake by the shoot, however, will be influenced by the climatic conditions at the time of exposure and the presence of foliage. Deposition and uptake are likely to change with leaf area development and the ability of radionuclides to penetrate the cuticle of the leaf changes with seasonal development. Transport of radionuclides to the fruit may also depend on the time of season, as the importance of the xylem and phloem transport routes can change with the growth and development of the fruit.

Agriculture↗

PubMed1999

Effect of tree and grass pollens and fungal spores on spring allergic rhinitis: a comparative study.

BACKGROUND: Current literature indicates tree pollen is less important than grass pollen as the cause of spring allergic rhinitis. The role of fungal spores is secondary and uncertain. OBJECTIVE: To assess the relative allergenicity of tree and grass pollen and fungal spores as the cause of spring allergic rhinitis in central Indiana. METHODS: (1) Chart review of 189 Indiana natives with seasonal allergic rhinitis to ascertain clinical sensitivity to tree or grass pollens. (2) A prospective study conducted in the spring of 1997 in 51 patients, correlating patients' symptom and medication scores with daily pollen and spore counts, obtained with a Burkard spore trap. RESULTS: One hundred thirty of 189 patients (69%) reported symptoms before May with positive prick test to at least one tree pollen. One hundred thirty-four patients (71%) had symptoms in May and June with positive test to grass pollen. The ratio between the two groups is 1:1, in contrast to a ratio of 1:4 derived from the literature. The prospective study revealed a symptom score increase parallel to the rise of tree pollen counts beginning in mid-March and reaching a plateau in early May prior to the onset of grass season. Medication use continued to increase and peaked at the height of grass pollination. Spore counts increased in late May and stayed at high levels throughout June, yet symptom and medication scores steadily declined following the peak of grass pollination in early June. CONCLUSIONS: This study suggests that in central Indiana, tree pollen is more important as the cause of spring allergic rhinitis than that suggested by the literature. This study confirmed previous observations that fungal spores are substantially less allergenic than pollens.

Adolescent↗

PubMed2001

Finding the right decision tree's induction strategy for a hard real world problem.

Decision trees have been already successfully used in medicine, but as in traditional statistics, some hard real world problems can not be solved successfully using the traditional way of induction. In our experiments we tested various methods for building univariate decision trees in order to find the best induction strategy. On a hard real world problem of the Orthopaedic fracture data with 2637 cases, described by 23 attributes and a decision with three possible values, we built decision trees with four classical approaches, one hybrid approach where we combined neural networks and decision trees, and with an evolutionary approach. The results show that all approaches had problems with either accuracy, sensitivity, or decision tree size. The comparison shows that the best compromise in hard real world problem decision trees building is the evolutionary approach.

Algorithms↗

PubMed2005

Development and application of an urban tree air quality score for photochemical pollution episodes using the Birmingham, United Kingdom, area as a case study.

An atmospheric chemistry model (CiTTyCAT) is used to quantify the effects of trees on urban air quality in scenarios of high photochemical pollution. The combined effects of both pollutant deposition to and emission of biogenic volatile organic compounds (BVOC) from the urban forest are considered, and the West Midlands, metropolitan area in the UK is used as a case study. While all trees can be beneficial to air quality in terms of the deposition of O3, NO2, CO, and HNO3, some trees have the potential to contribute to the formation of O3 due to the reaction of BVOC and NOx. A number of model scenarios are used to develop an urban tree air quality score (UTAQS) that ranks trees in order of their potential to improve air quality. Of the 30 species considered, pine, larch, and silver birch have the greatest potential to improve urban air quality, while oaks, willows, and poplars can worsen downwind air quality if planted in very large numbers. The UTAQS classification is designed with practitioners in mind, to help them achieve sustainable urban air quality. The UTAQS classification is applicable to all urban areas of the UK and other mid-latitude, temperate climate zones that have tree species common to those found in UK urban areas. The modeling approach used here is directly applicable to all areas of the world given the appropriate input data. It provides a tool that can help to achieve future sustainable urban air quality.

Air↗

PubMed1988

Probability and category redefinition in the fault tree paradigm.

Fault trees have been advocated as aids for problem solvers. However, research has suggested limitations in their usefulness. Fischhoff, Slovic, and Lichtenstein (1978) found that subjects given incomplete (pruned) trees were insensitive to omissions; these authors hypothesized that Tversky and Kahneman's (1974) availability heuristic was the mediating factor. Using a within-subjects design, subjects in Experiment 1 received both full and pruned trees and estimated probabilities for various reasons why a car would fail to start. To increase the availability of omissions, some Experiment 1 subjects first generated possible causes of starting failure. The basic Fischhoff et al. findings were replicated, but several aspects of the results argued against the availability hypothesis as the mechanism for judgment. Instead, subjects appeared to idiosyncratically redefine category membership when making judgments based upon pruned trees. By employing a sorting task in Experiment 2 we corroborated the results of Experiment 1: Subjects do redefine the actual contents of the categories when faced with an omission from the fault tree. The implications of these results for the use of fault trees as a problem solving aid are discussed.

Decision Trees↗

PubMed2000

Soil pathogens and spatial patterns of seedling mortality in a temperate tree.

The Janzen-Connell hypothesis proposes that host-specific, distance- and/or density-dependent predators and herbivores maintain high tree diversity in tropical forests. Negative feedback between plant and soil communities could be a more effective mechanism promoting species coexistence because soil pathogens can increase rapidly in the presence of their host, causing conditions unfavourable for local conspecific recruitment. Here we show that a soil pathogen leads to patterns of seedling mortality in a temperate tree (Prunus serotina) as predicted by the Janzen-Connell hypothesis. In the field, the mean distance to parent of seedling cohorts shifted away from maternal trees over a period of 3 years. Seedlings were grown in soil collected 0-5 m or 25-30 m from Prunus trees. Sterilization of soil collected beneath trees improved seedling survival relative to unsterilized soil, whereas sterilization of distant soil did not affect survival. Pythium spp., isolated from roots of dying seedlings and used to inoculate healthy seedlings, decreased survival by 65% relative to controls. Our results provide the most complete evidence that native pathogens influence tree distributions, as predicted by the Janzen-Connell hypothesis, and suggest that similar ecological mechanisms operate in tropical and temperate forests.

Biological Evolution↗

PubMed2004

Pervasive alteration of tree communities in undisturbed Amazonian forests.

Amazonian rainforests are some of the most species-rich tree communities on earth. Here we show that, over the past two decades, forests in a central Amazonian landscape have experienced highly nonrandom changes in dynamics and composition. Our analyses are based on a network of 18 permanent plots unaffected by any detectable disturbance. Within these plots, rates of tree mortality, recruitment and growth have increased over time. Of 115 relatively abundant tree genera, 27 changed significantly in population density or basal area--a value nearly 14 times greater than that expected by chance. An independent, eight-year study in nearby forests corroborates these shifts in composition. Contrary to recent predictions, we observed no increase in pioneer trees. However, genera of faster-growing trees, including many canopy and emergent species, are increasing in dominance or density, whereas genera of slower-growing trees, including many subcanopy species, are declining. Rising atmospheric CO2 concentrations may explain these changes, although the effects of this and other large-scale environmental alterations remain uncertain. These compositional changes could have important impacts on the carbon storage, dynamics and biota of Amazonian forests.

Atmosphere↗

PubMed2000

Estimation of gene flow in the tropical-rainforest tree Neobalanocarpus heimii (Dipterocarpaceae), inferred from paternity analysis.

Pollen flow and population genetic structure among 30 potentially flowering individuals of Neobalanocarpus heimii, a tropical emergent tree, were investigated in a lowland tropical rainforest of Malaysia using microsatellite polymorphism. The 248 offspring in the vicinity of five reproductive trees of the 30 potentially flowering trees were used in paternity analysis for pollen-flow study. Four primer pairs, developed in different species of dipterocarps, were adopted to detect microsatellite polymorphism. Based upon microsatellite polymorphism, pollen flow and seed migration were detected. Pollen-flow events of more than 400 m were observed directly, based on paternity analysis in the study plot. The estimated average mating distance of the five reproductive trees was 524 m. This result suggests that reproduction of this species is mediated by a long-distance pollinator. The haplotypes of some offspring were not compatible with the nearest reproductive tree. Thus, the results suggest that some seeds are dispersed by a seed dispersal vector. Investigation of genetic structure showed significant and negative correlation of genetic relatedness and spatial distances between the 30 potentially flowering trees, but this correlation was weak. We suggest that long-distance gene flow and seed migration are responsible for the poorly developed genetic structure of this species.

Ecosystem↗

PubMed2000

Treatment of epileptic seizures as medical emergencies: a prospective analysis of a decision tree for nonmedically trained staff.

The aim of this study was to evaluate the benefit of treating every epileptic seizure as an emergency and to propose a decision tree for use by nonmedical staff. Published literature on emergency medical treatment for seizures was reviewed. A detailed decision tree was developed for use by nonmedical staff. Its effectiveness was prospectively analysed over 16 months. Each seizure was logged, and its duration and severity were recorded. Type, dose, and time of antiepileptic treatment were noted. Results were compared with a 6-month retrospective review. Initiation of antiepileptic drug treatment 5 or 7 minutes after seizure onset was indicated in the tree. Rectal diazepam or lorazepam, or fast-dissolving lorazepam was used. Use of the decision tree resulted in decreased duration of seizures, which lasted up to 18 hours in the retrospective review compared with only 37 minutes in the prospective study. Using this tree, nonmedical staff can appropriately treat adults experiencing seizures. Duration, severity, and frequency of seizures decreased when every seizure was treated as a medical emergency. Implementation of a decision tree is recommended for establishments with patients prone to seizures. It can also be taught to caregivers and parents of patients with well-known epilepsy.

Anticonvulsants↗

PubMed2003

The use of stable isotopes to evaluate water mixing and water use by flood plain trees along the Garonne valley.

Before the confluence of the Tarn, the Garonne valley was the driest area in the entire south-west of France, due to the relatively low rainfall and low summer discharge of the Garonne River and its tributaries. The natural abundance of the stable isotope of oxygen (18O) and ionic charge of surface and ground water were used to estimate the water source for the Garonne River and phreatic subsurface water. We also measured these constituents in the sap of trees at several flood plain sites to better understand the source of water used by these trees. 18O signatures and conductivity in the Garonne River indicated that the predominance of water was from high altitude surface runoff from the Pyrenees Mountains. Tributary inputs had little effect on isotopic identity, but had a small effect on the conductivity. The isotopic signature and ionic conductivity of river water (delta18O: -9.1 per thousand to -9.0 per thousand, conductivity: 217-410 microS/cm) was distinctly different from groundwater (delta18O: -7.1 per thousand to -6.6 per thousand, conductivity: 600-900 microS/cm). Isotopic signatures from the sap of trees on the flood plain showed that the water source was shallow subsurface water (<30 cm), whereas trees further from the river relied on deeper ground water (>1 m). Trees at both locations maintained sap with ionic charges much greater (2.3-3.7x) than that of source water. The combined use of 18O signatures and ionic conductivity appears to be a potent tool to determine water sources on geographic scales, and source and use patterns by trees at the local forest scale. These analyses also show promise for better understanding of the effects of anthropogenic land-use and water-use changes on flood plain forest dynamics.

Disasters↗

PubMed2000

Testing hybridization hypotheses based on incongruent gene trees.

Hybridization is an important evolutionary mechanism in plants and has been increasingly documented in animals. Difficulty in reconstruction of reticulate evolution, however, has been a long-standing problem in phylogenetics. Consequently, hybrid speciation may play a major role in causing topological incongruence between gene trees. The incongruence, in turn, offers an opportunity to detect hybrid speciation. Here we characterized certain distinctions between hybridization and other biological processes, including lineage sorting, paralogy, and lateral gene transfer, that are responsible for topological incongruence between gene trees. Consider two incongruent gene trees with three taxa, A, B, and C, where B is a sister group of A on gene tree 1 but a sister group of C on gene tree 2. With a theoretical model based on the molecular clock, we demonstrate that time of divergence of each gene between taxa A and C is nearly equal in the case of hybridization (B is a hybrid) or lateral gene transfer, but differs significantly in the case of lineage sorting or paralogy. After developing a bootstrap test to test these alternative hypotheses, we extended the model and test to account for incongruent gene trees with numerous taxa. Computer simulation studies supported the validity of the theoretical model and bootstrap test when each gene evolved at a constant rate. The computer simulation also suggested that the model remained valid as long as the rate heterogeneity was occurring proportionally in the same taxa for both genes. Although the model could not test hypotheses of hybridization versus lateral gene transfer as the cause of incongruence, these two processes may be distinguished by comparing phylogenies of multiple unlinked genes.

Biological Evolution↗

PubMed2002

Impacts of climate change on the tree line.

The possible effects of climate change on the advance of the tree line are considered. As temperature, elevated CO(2) and nitrogen deposition co-vary, it is impossible to disentangle their impacts without performing experiments. However, it does seem very unlikely that photosynthesis per se and, by implication, factors that directly influence photosynthesis, such as elevated CO(2), will be as important as those factors which influence the capacity of the tree to use the products of photosynthesis, such as temperature. Moreover, temperature limits growth more severely than it limits photosynthesis over the temperature range 5-20 degrees C. If it is assumed that growth and reproduction are controlled by temperature, a rapid advance of the tree line would be predicted. Indeed, some authors have provided photographic evidence and remotely sensed data that suggest this is, in fact, occurring. In regions inhabited by grazing animals, the advance of the tree line will be curtailed, although growth of trees below the tree line will of course increase substantially.

Climate↗