Forest stand structure, productivity, and age mediate climatic effects on aspen decline

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Bell, David M.; Bradford, John B.; Lauenroth, William K.

2014-01-01

Because forest stand structure, age, and productivity can mediate the impacts of climate on quaking aspen (Populus tremuloides) mortality, ignoring stand-scale factors limits inference on the drivers of recent sudden aspen decline. Using the proportion of aspen trees that were dead as an index of recent mortality at 841 forest inventory plots, we examined the relationship of this mortality index to forest structure and climate in the Rocky Mountains and Intermountain Western United States. We found that forest structure explained most of the patterns in mortality indices, but that variation in growing-season vapor pressure deficit and winter precipitation over the last 20 years was important. Mortality index sensitivity to precipitation was highest in forests where aspen exhibited high densities, relative basal areas, quadratic mean diameters, and productivities, whereas sensitivity to vapor pressure deficit was highest in young forest stands. These results indicate that the effects of drought on mortality may be mediated by forest stand development, competition with encroaching conifers, and physiological vulnerabilities of large trees to drought. By examining mortality index responses to both forest structure and climate, we show that forest succession cannot be ignored in studies attempting to understand the causes and consequences of sudden aspen decline.

Elevated Rocky Mountain elk numbers prevent positive effects of fire on quaking aspen (Populus tremuloides) recruitment

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Smith, David Solance; Fettig, Stephen M.; Bowker, Matthew A.

2016-01-01

Quaking aspen (Populus tremuloides) is the most widespread tree species in North America and has supported a unique ecosystem for tens of thousands of years, yet is currently threatened by dramatic loss and possible local extinctions. While multiple factors such as climate change and fire suppression are thought to contribute to aspen’s decline, increased browsing by elk (Cervus elaphus), which have experienced dramatic population increases in the last ∼80 years, may severely inhibit aspen growth and regeneration. Fires are known to favor aspen recovery, but in the last several decades the spatial scale and intensity of wildfires has greatly increased, with poorly understood ramifications for aspen growth. Here, focusing on the 2000 Cerro Grande fire in central New Mexico – one of the earliest fires described as a “mega-fire” - we use three methods to examine the impact of elk browsing on aspen regeneration after a mega-fire. First, we use an exclosure experiment to show that aspen growing in the absence of elk were 3× taller than trees growing in the presence of elk. Further, aspen that were both protected from elk and experienced burning were 8.5× taller than unburned trees growing in the presence of elk, suggesting that the combination of release from herbivores and stimulation from fire creates the largest aspen growth rates. Second, using surveys at the landscape level, we found a correlation between elk browsing intensity and aspen height, such that where elk browsing was highest, aspen were shortest. This relationship between elk browsing intensity and aspen height was stronger in burned (r = −0.53) compared to unburned (r = −0.24) areas. Third, in conjunction with the landscape-level surveys, we identified possible natural refugia, microsites containing downed logs, shrubs etc. that may inhibit elk browsing by physically blocking aspen from elk or by impeding elk’s ability to move through the forest patch. We did not find any

Fire regimes of quaking aspen in the Mountain West

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Shinneman, Douglas J.; Baker, William L.; Rogers, Paul C.; Kulakowski, Dominik

2013-01-01

Quaking aspen (Populus tremuloides Michx.) is the most widespread tree species in North America, and it is found throughout much of the Mountain West (MW) across a broad range of bioclimatic regions. Aspen typically regenerates asexually and prolifically after fire, and due to its seral status in many western conifer forests, aspen is often considered dependent upon disturbance for persistence. In many landscapes, historical evidence for post-fire aspen establishment is clear, and following extended fire-free periods senescing or declining aspen overstories sometimes lack adequate regeneration and are succeeding to conifers. However, aspen also forms relatively stable stands that contain little or no evidence of historical fire. In fact, aspen woodlands range from highly fire-dependent, seral communities to relatively stable, self-replacing, non-seral communities that do not require fire for persistence. Given the broad geographic distribution of aspen, fire regimes in these forests likely co-vary spatially with changing community composition, landscape setting, and climate, and temporally with land use and climate – but relatively few studies have explicitly focused on these important spatiotemporal variations. Here we reviewed the literature to summarize aspen fire regimes in the western US and highlight knowledge gaps. We found that only about one-fourth of the 46 research papers assessed for this review could be considered fire history studies (in which mean fire intervals were calculated), and all but one of these were based primarily on data from fire-scarred conifers. Nearly half of the studies reported at least some evidence of persistent aspen in the absence of fire. We also found that large portions of the MW have had little or no aspen fire history research. As a result of this review, we put forth a classification framework for aspen that is defined by key fire regime parameters (fire severity and probability), and that reflects underlying biophysical

Long-term monitoring of western aspen--lessons learned.

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Strand, E K; Bunting, S C; Starcevich, L A; Nahorniak, M T; Dicus, G; Garrett, L K

2015-08-01

Aspen woodland is an important ecosystem in the western United States. Aspen is currently declining in western mountains; stressors include conifer expansion due to fire suppression, drought, disease, heavy wildlife and livestock use, and human development. Forecasting of tree species distributions under future climate scenarios predicts severe losses of western aspen within the next 50 years. As a result, aspen has been selected as one of 14 vital signs for long-term monitoring by the National Park Service Upper Columbia Basin Network. This article describes the development of a monitoring protocol for aspen including inventory mapping, selection of sampling locations, statistical considerations, a method for accounting for spatial dependence, field sampling strategies, and data management. We emphasize the importance of collecting pilot data for use in statistical power analysis and semi-variogram analysis prior to protocol implementation. Given the spatial and temporal variability within aspen stem size classes, we recommend implementing permanent plots that are distributed spatially within and among stands. Because of our careful statistical design, we were able to detect change between sampling periods with desired confidence and power. Engaging a protocol development and implementation team with necessary and complementary knowledge and skills is critical for success. Besides the project leader, we engaged field sampling personnel, GIS specialists, statisticians, and a data management specialist. We underline the importance of frequent communication with park personnel and network coordinators.

Vertical and horizontal root distribution of mature aspen clones: mechanisms for resource acquisition

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Landhäusser, S. M.; Snedden, J.; Silins, U.; Devito, K. J.

2012-04-01

Spatial root distribution, root morphology, and intra- and inter-clonal connections of mature boreal trembling aspen clones (Populus tremuloides Michx.) were explored to shed light on the functional relationships between vertical and horizontal distribution of roots and the variation in soil water availability along hill slopes. Root systems of mature aspen were hydraulically excavated in large plots (6 m wide and 12 m long) and to a depth of 30 cm. Most aspen roots were located in the upper 20 cm of the soil and fine and coarse root occupancy was highest in the lower slope positions and lowest towards the upper hill slope position likely because of soil moisture availability. Observation of the root system distribution along the hill slope correlated well with the observation of greater leaf area carried by trees growing at the lower portion of the hill slope. Interestingly, trees growing at the bottom of the slope required also less sapwood area to support the same amount of leaf area of trees growing at the top of a slope. These observations appear to be closely related to soil moisture availability and with that greater productivity at the bottom of the slope. However, trees growing on the upper slope tended to have long lateral roots extending downslope, which suggests long distance water transport through these lateral feeder roots. Genetic analysis indicated that both intra- and inter-clonal root connections occur in aspen, which can play a role in the sharing of resources along moisture gradients. Root systems of boreal aspen growing on upper slope positions exhibited a combination of three attributes (1) asymmetric lateral root systems, that are skewed downslope, (2) deeper taproots, and (3) intra and inter-clonal root connections, which can all be considered adaptive strategies to avoid drought stress in upper slope positions.

Initial soil respiration response to biomass harvesting and green-tree retention in aspen-dominated forests of the Great Lakes region

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Kurth, Valerie J.; Bradford, John B.; Slesak, Robert A.; D'Amato, Anthony W.

2014-01-01

Contemporary forest management practices are increasingly designed to optimize novel objectives, such as maximizing biomass feedstocks and/or maintaining ecological legacies, but many uncertainties exist regarding how these practices influence forest carbon (C) cycling. We examined the responses of soil respiration (Rs) to biomass harvesting and green-tree retention in an effort to empirically assess their impacts on C cycling. We measured Rs and soil microclimatic variables over four growing seasons following implementation of these management practices using a fully replicated, operational-scale experiment in aspen-dominated forests in northern Minnesota. Treatments included three levels of biomass removal within harvested areas: whole-tree harvest (no slash deliberately retained), 20% slash retained, and stem-only harvest (all slash retained), and two levels of green-tree retention: 0.1 ha aggregate or none. The relative amount of biomass removed had a negligible effect on Rs in harvested areas, but treatment effects were probably obscured by heterogeneous slash configurations and rapid post-harvest regeneration of aspen in all of the treatments. Discrete measurements of Rs and soil temperature within green-tree aggregates were not discernible from surrounding harvested areas or unharvested control stands until the fourth year following harvest, when Rs was higher in unharvested controls than in aggregates and harvested stands. Growing season estimates of Rs showed that unharvested control stands had higher Rs than both harvested stands and aggregates in the first and third years following harvest. Our results suggest that retention of larger forest aggregates may be necessary to maintain ecosystem-level responses similar to those in unharvested stands. Moreover, they highlight the innate complexity of operational-scale research and suggest that the initial impacts of biomass harvest on Rs may be indiscernible from traditional harvest in systems where incidental

Habitone analysis of quaking aspen in the Utah Book Cliffs: Effects of site water demand and conifer cover

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Joseph O. Sexton; R. Douglas Ramsey; Dale L. Bartos

2006-01-01

Quaking aspen (Populus tremuloides Michx.) is the most widely distributed tree species in North America, but its presence is declining across much of the Western United States. Aspen decline is complex, but results largely from two factors widely divergent in temporal scale: (1) Holocene climatic drying of the region has led to water limitation of aspen seedling...

Allozyme and microsatellite data reveal small clone size and high genetic diversity in aspen in the southern Cascade Mountains

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Jennifer DeWoody; Thomas H. Rickman; Bobette E. Jones; Valerie D. Hipkins

2009-01-01

The most widely distributed tree in North America, quaking aspen (Populus tremuloides, Michx.), reproduces sexually via seed and clonally via suckers. The size of aspen clones varies geographically, generally smaller in the east and large in the arid Intermountain West. In order to describe clone size and genetic structure of aspen in the southern Cascade...

Are wolves saving Yellowstone's aspen? A landscape-level test of a behaviorally mediated trophic cascade.

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Kauffman, Matthew J; Brodie, Jedediah F; Jules, Erik S

2010-09-01

Behaviorally mediated trophic cascades (BMTCs) occur when the fear of predation among herbivores enhances plant productivity. Based primarily on systems involving small-bodied predators, BMTCs have been proposed as both strong and ubiquitous in natural ecosystems. Recently, however, synthetic work has suggested that the existence of BMTCs may be mediated by predator hunting mode, whereby passive (sit-and-wait) predators have much stronger effects than active (coursing) predators. One BMTC that has been proposed for a wide-ranging active predator system involves the reintroduction of wolves (Canis lupus) to Yellowstone National Park, USA, which is thought to be leading to a recovery of trembling aspen (Populus tremuloides) by causing elk (Cervus elaphus) to avoid foraging in risky areas. Although this BMTC has been generally accepted and highly popularized, it has never been adequately tested. We assessed whether wolves influence aspen by obtaining detailed demographic data on aspen Stands using tree rings and by monitoring browsing levels in experimental elk exclosures arrayed across a gradient of predation risk for three years. Our study demonstrates that the historical failure of aspen to regenerate varied widely among stands (last recruitment year ranged from 1892 to 1956), and our data do not indicate an abrupt cessation of recruitment. This pattern of recruitment failure appears more consistent with a gradual increase in elk numbers rather than a rapid behavioral shift in elk foraging following wolf extirpation. In addition, our estimates of relative survivorship of young browsable aspen indicate that aspen are not currently recovering in Yellowstone, even in the presence of a large wolf population. Finally, in an experimental test of the BMTC hypothesis we found that the impacts of elk browsing on aspen demography are not diminished in sites where elk are at higher risk of predation by wolves. These findings suggest the need to further evaluate how trophic

Bryophyte species richness on retention aspens recovers in time but community structure does not.

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Oldén, Anna; Ovaskainen, Otso; Kotiaho, Janne S; Laaka-Lindberg, Sanna; Halme, Panu

2014-01-01

Green-tree retention is a forest management method in which some living trees are left on a logged area. The aim is to offer 'lifeboats' to support species immediately after logging and to provide microhabitats during and after forest re-establishment. Several studies have shown immediate decline in bryophyte diversity after retention logging and thus questioned the effectiveness of this method, but longer term studies are lacking. Here we studied the epiphytic bryophytes on European aspen (Populus tremula L.) retention trees along a 30-year chronosequence. We compared the bryophyte flora of 102 'retention aspens' on 14 differently aged retention sites with 102 'conservation aspens' on 14 differently aged conservation sites. We used a Bayesian community-level modelling approach to estimate the changes in bryophyte species richness, abundance (area covered) and community structure during 30 years after logging. Using the fitted model, we estimated that two years after logging both species richness and abundance of bryophytes declined, but during the following 20-30 years both recovered to the level of conservation aspens. However, logging-induced changes in bryophyte community structure did not fully recover over the same time period. Liverwort species showed some or low potential to benefit from lifeboating and high potential to re-colonise as time since logging increases. Most moss species responded similarly, but two cushion-forming mosses benefited from the logging disturbance while several weft- or mat-forming mosses declined and did not re-colonise in 20-30 years. We conclude that retention trees do not function as equally effective lifeboats for all bryophyte species but are successful in providing suitable habitats for many species in the long-term. To be most effective, retention cuts should be located adjacent to conservation sites, which may function as sources of re-colonisation and support the populations of species that require old-growth forests.

Bryophyte species richness on retention aspens recovers in time but community structure does not.

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Anna Oldén

Full Text Available Green-tree retention is a forest management method in which some living trees are left on a logged area. The aim is to offer 'lifeboats' to support species immediately after logging and to provide microhabitats during and after forest re-establishment. Several studies have shown immediate decline in bryophyte diversity after retention logging and thus questioned the effectiveness of this method, but longer term studies are lacking. Here we studied the epiphytic bryophytes on European aspen (Populus tremula L. retention trees along a 30-year chronosequence. We compared the bryophyte flora of 102 'retention aspens' on 14 differently aged retention sites with 102 'conservation aspens' on 14 differently aged conservation sites. We used a Bayesian community-level modelling approach to estimate the changes in bryophyte species richness, abundance (area covered and community structure during 30 years after logging. Using the fitted model, we estimated that two years after logging both species richness and abundance of bryophytes declined, but during the following 20-30 years both recovered to the level of conservation aspens. However, logging-induced changes in bryophyte community structure did not fully recover over the same time period. Liverwort species showed some or low potential to benefit from lifeboating and high potential to re-colonise as time since logging increases. Most moss species responded similarly, but two cushion-forming mosses benefited from the logging disturbance while several weft- or mat-forming mosses declined and did not re-colonise in 20-30 years. We conclude that retention trees do not function as equally effective lifeboats for all bryophyte species but are successful in providing suitable habitats for many species in the long-term. To be most effective, retention cuts should be located adjacent to conservation sites, which may function as sources of re-colonisation and support the populations of species that require old

Moderate-scale mapping methods of aspen stand types: a case study for Cedar Mountain in southern Utah

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Chad M. Oukrop; David M. Evans; Dale L. Bartos; R. Douglas Ramsey; Ronald J. Ryel

2011-01-01

Quaking aspen (Populus tremuloides Michx.) are the most widely distributed tree species across North America, but its dominance is declining in many areas of the western United States, with certain areas experiencing rapid mortality events over the past decade. The loss of aspen from western landscapes will continue to profoundly impact biological, commercial, and...

Factors Influencing the Tissue Culture and the Agrobacterium tumefaciens-Mediated Transformation of Hybrid Aspen and Poplar Clones.

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De Block, M

1990-07-01

Tissue culture conditions and transformation have been established for both aspen and poplar. The use of previously described culture conditions resulted in shoot tip necrosis in the shoot cultures and necrosis of stem and leaf explants. Shoot tip necrosis could be overcome by buffering the medium with 2-(N-morpholino)ethanesulfonic acid and Ca-gluconate and by growing the shoots below 25 degrees C. Necrosis of the explants was probably due to an accumulation of ammonium in the explants and could be overcome by adapting the NO(3) (-)/NH(4) (+) ratio of the media. Stem explants of established shoot cultures of the aspen hybrid Populus alba x P. tremula and of the poplar hybrid Populus trichocarpa x P. deltoides were cocultivated with Agrobacterium strains having chimeric bar and neo genes on their disarmed tDNAs. Transformed aspen shoots were obtained from 30 to 40% of the explants, while transformed poplar shoots were obtained from 10% of the explants. Extracts from the transformed trees contained high phosphinotricin acetyltransferase and neomycin phosphotransferase activities, and the trees contained one to three copies of the chimeric genes. The transformed trees were completely resistant to the commercial preparations of the herbicide phosphinotricin (glufosinate), while control trees were not.

Genetic Variation in Functional Traits Influences Arthropod Community Composition in Aspen (Populus tremula L.)

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Robinson, Kathryn M.; Ingvarsson, Pär K.; Jansson, Stefan; Albrectsen, Benedicte R.

2012-01-01

We conducted a study of natural variation in functional leaf traits and herbivory in 116 clones of European aspen, Populus tremula L., the Swedish Aspen (SwAsp) collection, originating from ten degrees of latitude across Sweden and grown in a common garden. In surveys of phytophagous arthropods over two years, we found the aspen canopy supports nearly 100 morphospecies. We identified significant broad-sense heritability of plant functional traits, basic plant defence chemistry, and arthropod community traits. The majority of arthropods were specialists, those coevolved with P. tremula to tolerate and even utilize leaf defence compounds. Arthropod abundance and richness were more closely related to plant growth rates than general chemical defences and relationships were identified between the arthropod community and stem growth, leaf and petiole morphology, anthocyanins, and condensed tannins. Heritable genetic variation in plant traits in young aspen was found to structure arthropod community; however no single trait drives the preferences of arthropod folivores among young aspen genotypes. The influence of natural variation in plant traits on the arthropod community indicates the importance of maintaining genetic variation in wild trees as keystone species for biodiversity. It further suggests that aspen can be a resource for the study of mechanisms of natural resistance to herbivores. PMID:22662190

Genetic variation in functional traits influences arthropod community composition in aspen (Populus tremula L..

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Kathryn M Robinson

Full Text Available We conducted a study of natural variation in functional leaf traits and herbivory in 116 clones of European aspen, Populus tremula L., the Swedish Aspen (SwAsp collection, originating from ten degrees of latitude across Sweden and grown in a common garden. In surveys of phytophagous arthropods over two years, we found the aspen canopy supports nearly 100 morphospecies. We identified significant broad-sense heritability of plant functional traits, basic plant defence chemistry, and arthropod community traits. The majority of arthropods were specialists, those coevolved with P. tremula to tolerate and even utilize leaf defence compounds. Arthropod abundance and richness were more closely related to plant growth rates than general chemical defences and relationships were identified between the arthropod community and stem growth, leaf and petiole morphology, anthocyanins, and condensed tannins. Heritable genetic variation in plant traits in young aspen was found to structure arthropod community; however no single trait drives the preferences of arthropod folivores among young aspen genotypes. The influence of natural variation in plant traits on the arthropod community indicates the importance of maintaining genetic variation in wild trees as keystone species for biodiversity. It further suggests that aspen can be a resource for the study of mechanisms of natural resistance to herbivores.

Global transcriptomic profiling of aspen trees under elevated [CO2] to identify potential molecular mechanisms responsible for enhanced radial growth.

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Wei, Hairong; Gou, Jiqing; Yordanov, Yordan; Zhang, Huaxin; Thakur, Ramesh; Jones, Wendy; Burton, Andrew

2013-03-01

Aspen (Populus tremuloides) trees growing under elevated [CO(2)] at a free-air CO(2) enrichment (FACE) site produced significantly more biomass than control trees. We investigated the molecular mechanisms underlying the observed increase in biomass by producing transcriptomic profiles of the vascular cambium zone (VCZ) and leaves, and then performed a comparative study to identify significantly changed genes and pathways after 12 years exposure to elevated [CO(2)]. In leaves, elevated [CO(2)] enhanced expression of genes related to Calvin cycle activity and linked pathways. In the VCZ, the pathways involved in cell growth, cell division, hormone metabolism, and secondary cell wall formation were altered while auxin conjugation, ABA synthesis, and cytokinin glucosylation and degradation were inhibited. Similarly, the genes involved in hemicellulose and pectin biosynthesis were enhanced, but some genes that catalyze important steps in lignin biosynthesis pathway were inhibited. Evidence from systemic analysis supported the functioning of multiple molecular mechanisms that underpin the enhanced radial growth in response to elevated [CO(2)].

Can Carbon Fluxes Explain Differences in Soil Organic Carbon Storage under Aspen and Conifer Forest Overstories?

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Antra Boča

2017-04-01

Full Text Available Climate- and management-induced changes in tree species distributions are raising questions regarding tree species-specific effects on soil organic carbon (SOC storage and stability. Quaking aspen (Populus tremuloides Michx. is the most widespread tree species in North America, but fire exclusion often promotes the succession to conifer dominated forests. Aspen in the Western US have been found to store more SOC in the mineral soil than nearby conifers, but we do not yet fully understand the source of this differential SOC accumulation. We measured total SOC storage (0–50 cm, characterized stable and labile SOC pools, and quantified above- and belowground litter inputs and dissolved organic carbon (DOC fluxes during snowmelt in plots located in N and S Utah, to elucidate the role of foliage vs. root detritus in SOC storage and stabilization in both ecosystems. While leaf litterfall was twice as high under aspen as under conifers, input of litter-derived DOC with snowmelt water was consistently higher under conifers. Fine root (<2 mm biomass, estimated root detritus input, and root-derived DOC fluxes were also higher under conifers. A strong positive relationship between root and light fraction C content suggests that root detritus mostly fueled the labile fraction of SOC. Overall, neither differences in above- and belowground detritus C inputs nor in detritus-derived DOC fluxes could explain the higher and more stable SOC pools under aspen. We hypothesize that root–microbe–soil interactions in the rhizosphere are more likely to drive these SOC pool differences.

Testing Transgenic Aspen Plants with bar Gene for Herbicide Resistance under Semi-natural Conditions.

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Lebedev, V G; Faskhiev, V N; Kovalenko, N P; Shestibratov, K A; Miroshnikov, A I

2016-01-01

Obtaining herbicide resistant plants is an important task in the genetic engineering of forest trees. Transgenic European aspen plants (Populus tremula L.) expressing the bar gene for phosphinothricin resistance have been produced using Agrobacterium tumefaciens-mediated transformation. Successful genetic transformation was confirmed by PCR analysis for thirteen lines derived from two elite genotypes. In 2014-2015, six lines were evaluated for resistance to herbicide treatment under semi-natural conditions. All selected transgenic lines were resistant to the herbicide Basta at doses equivalent to 10 l/ha (twofold normal field dosage) whereas the control plants died at 2.5 l/ha. Foliar NH4-N concentrations in transgenic plants did not change after treatment. Extremely low temperatures in the third ten-day period of October 2014 revealed differences in freeze tolerance between the lines obtained from Pt of f2 aspen genotypes. Stable expression of the bar gene after overwintering outdoors was confirmed by RT-PCR. On the basis of the tests, four transgenic aspen lines were selected. The bar gene could be used for retransformation of transgenic forest trees expressing valuable traits, such as increased productivity.

Variable performance of outbreak defoliators on aspen clones exposed to elevated CO2 and O3

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Daniel A. Herms; William J. Mattson; David N. Karowe; Mark D. Coleman; Terry M. Trier; Bruce A. Birr; J. G. Isebrands

1996-01-01

Increasing atmospheric concentrations of ozone and CO2 affect many aspects of tree physiology. However, their effects on tree resistance to insects have received relatively little attention. The objectives of this study were to test the effects of elevated CO2 and ozone on the resistance of three quaking aspen (...

ASPEN Version 3.0

Science.gov (United States)

Rabideau, Gregg; Chien, Steve; Knight, Russell; Schaffer, Steven; Tran, Daniel; Cichy, Benjamin; Sherwood, Robert

2006-01-01

The Automated Scheduling and Planning Environment (ASPEN) computer program has been updated to version 3.0. ASPEN is a modular, reconfigurable, application software framework for solving batch problems that involve reasoning about time, activities, states, and resources. Applications of ASPEN can include planning spacecraft missions, scheduling of personnel, and managing supply chains, inventories, and production lines. ASPEN 3.0 can be customized for a wide range of applications and for a variety of computing environments that include various central processing units and random access memories.

Assessing aspen using remote sensing

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Randy Hamilton; Kevin Megown; Jeff DiBenedetto; Dale Bartos; Anne Mileck

2009-01-01

Large areas of aspen (Populus tremuloides) have disappeared and continue to disappear from western forests due to successional decline and sudden aspen decline (SAD). This loss of aspen ecosystems negatively impacts watersheds, wildlife, plants, and recreation. Much can still be done to restore aspen if timely and appropriate action is taken. However, land managers...

The yield of natural trembling aspen (populus tremula L.) stands (northern and eastern anatolia)

International Nuclear Information System (INIS)

Misir, M.; Misir, N.

2013-01-01

Trembling aspen (Populus tremula L.) is one of the most resistant to cold natural species in Turkey. In spite of its importance, there is no research on the yield. Hence, site productivity was determined and yield Table for undisturbed natural trembling aspen stands in Turkey was developed. Data were obtained from a total of 46 plots ranging in age from 17 to 82 years. Yield Table indicates that trembling aspen is very slow growing in young and middle age and Current Annual Increment (CAI) and Mean Annual Increment (MAI) values do not reach its maximum value, even at age 70. This is a proof that trembling aspen is not a fast growing species as expected. The reason for its slow growth is attributed to very short period of growth at very high altitudes. However, in the event of 50 years rotation age, mean annual volume increments of 8.0, 3.6 and 1.1 m3 are estimated for trembling aspen for site classes I, II and III, respectively. At extended rotations, trees of pole sizes could be obtained on all site classes. (author)

Tree species traits influence soil physical, chemical, and biological properties in high elevation forests.

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Edward Ayres

Full Text Available BACKGROUND: Previous studies have shown that plants often have species-specific effects on soil properties. In high elevation forests in the Southern Rocky Mountains, North America, areas that are dominated by a single tree species are often adjacent to areas dominated by another tree species. Here, we assessed soil properties beneath adjacent stands of trembling aspen, lodgepole pine, and Engelmann spruce, which are dominant tree species in this region and are distributed widely in North America. We hypothesized that soil properties would differ among stands dominated by different tree species and expected that aspen stands would have higher soil temperatures due to their open structure, which, combined with higher quality litter, would result in increased soil respiration rates, nitrogen availability, and microbial biomass, and differences in soil faunal community composition. METHODOLOGY/PRINCIPAL FINDINGS: We assessed soil physical, chemical, and biological properties at four sites where stands of aspen, pine, and spruce occurred in close proximity to one-another in the San Juan Mountains, Colorado. Leaf litter quality differed among the tree species, with the highest nitrogen (N concentration and lowest lignin:N in aspen litter. Nitrogen concentration was similar in pine and spruce litter, but lignin:N was highest in pine litter. Soil temperature and moisture were highest in aspen stands, which, in combination with higher litter quality, probably contributed to faster soil respiration rates from stands of aspen. Soil carbon and N content, ammonium concentration, and microbial biomass did not differ among tree species, but nitrate concentration was highest in aspen soil and lowest in spruce soil. In addition, soil fungal, bacterial, and nematode community composition and rotifer, collembolan, and mesostigmatid mite abundance differed among the tree species, while the total abundance of nematodes, tardigrades, oribatid mites, and prostigmatid

Spring leaf flush in aspen (Populus tremuloides) clones is altered by long-term growth at elevated carbon dioxide and elevated ozone concentration

International Nuclear Information System (INIS)

McGrath, Justin M.; Karnosky, David F.; Ainsworth, Elizabeth A.

2010-01-01

Early spring leaf out is important to the success of deciduous trees competing for light and space in dense forest plantation canopies. In this study, we investigated spring leaf flush and how long-term growth at elevated carbon dioxide concentration ([CO 2 ]) and elevated ozone concentration ([O 3 ]) altered leaf area index development in a closed Populus tremuloides (aspen) canopy. This work was done at the Aspen FACE experiment where aspen clones have been grown since 1997 in conditions simulating the [CO 2 ] and [O 3 ] predicted for ∼2050. The responses of two clones were compared during the first month of spring leaf out when CO 2 fumigation had begun, but O 3 fumigation had not. Trees in elevated [CO 2 ] plots showed a stimulation of leaf area index (36%), while trees in elevated [O 3 ] plots had lower leaf area index (-20%). While individual leaf area was not significantly affected by elevated [CO 2 ], the photosynthetic operating efficiency of aspen leaves was significantly improved (51%). There were no significant differences in the way that the two aspen clones responded to elevated [CO 2 ]; however, the two clones responded differently to long-term growth at elevated [O 3 ]. The O 3 -sensitive clone, 42E, had reduced individual leaf area when grown at elevated [O 3 ] (-32%), while the tolerant clone, 216, had larger mature leaf area at elevated [O 3 ] (46%). These results indicate a clear difference between the two clones in their long-term response to elevated [O 3 ], which could affect competition between the clones, and result in altered genotypic composition in future atmospheric conditions. - Spring leaf flush is stimulated by elevated [CO 2 ] and suppressed by elevated [O 3 ] in aspen (Populus tremuloides).

Factors affecting fall down rates of dead aspen (Populus tremuloides) biomass following severe drought in west-central Canada.

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Ted Hogg, Edward H; Michaelian, Michael

2015-05-01

Increases in mortality of trembling aspen (Populus tremuloides Michx.) have been recorded across large areas of western North America following recent periods of exceptionally severe drought. The resultant increase in standing, dead tree biomass represents a significant potential source of carbon emissions to the atmosphere, but the timing of emissions is partially driven by dead-wood dynamics which include the fall down and breakage of dead aspen stems. The rate at which dead trees fall to the ground also strongly influences the period over which forest dieback episodes can be detected by aerial surveys or satellite remote sensing observations. Over a 12-year period (2000-2012), we monitored the annual status of 1010 aspen trees that died during and following a severe regional drought within 25 study areas across west-central Canada. Observations of stem fall down and breakage (snapping) were used to estimate woody biomass transfer from standing to downed dead wood as a function of years since tree death. For the region as a whole, we estimated that >80% of standing dead aspen biomass had fallen after 10 years. Overall, the rate of fall down was minimal during the year following stem death, but thereafter fall rates followed a negative exponential equation with k = 0.20 per year. However, there was high between-site variation in the rate of fall down (k = 0.08-0.37 per year). The analysis showed that fall down rates were positively correlated with stand age, site windiness, and the incidence of decay fungi (Phellinus tremulae (Bond.) Bond. and Boris.) and wood-boring insects. These factors are thus likely to influence the rate of carbon emissions from dead trees following periods of climate-related forest die-off episodes. © 2014 Her Majesty the Queen in Right of Canada Global Change Biology © 2014 John Wiley & Sons Ltd Reproduced with the permission of the Minister of Natural Resources Canada.

The potential of aspen clonal forestry in Alberta: breeding regions and estimates of genetic gain from selection.

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Tim Gylander

Full Text Available BACKGROUND: Aspen naturally grows in large, single-species, even-aged stands that regenerate clonally after fire disturbance. This offers an opportunity for an intensive clonal forestry system that closely emulates the natural life history of the species. In this paper, we assess the potential of genetic tree improvement and clonal deployment to enhance the productivity of aspen forests in Alberta. We further investigate geographic patterns of genetic variation in aspen and infer forest management strategies under uncertain future climates. METHODOLOGY/PRINCIPAL FINDINGS: Genetic variation among 242 clones from Alberta was evaluated in 13 common garden trials after 5-8 growing seasons in the field. Broad-sense heritabilities for height and diameter at breast height (DBH ranged from 0.36 to 0.64, allowing 5-15% genetic gains in height and 9-34% genetic gains in DBH. Geographic partitioning of genetic variance revealed predominant latitudinal genetic differentiation. We further observed that northward movement of clones almost always resulted in increased growth relative to local planting material, while southward movement had a strong opposite effect. CONCLUSION/SIGNIFICANCE: Aspen forests are an important natural resource in western Canada that is used for pulp and oriented strandboard production, accounting for ~40% of the total forest harvest. Moderate to high broad-sense heritabilities in growth traits suggest good potential for a genetic tree improvement program with aspen. Significant productivity gains appear possible through clonal selection from existing trials. We propose two breeding regions for Alberta, and suggest that well-tested southern clones may be used in the northern breeding region, accounting for a general warming trend observed over the last several decades in Alberta.

The Potential of Aspen Clonal Forestry in Alberta: Breeding Regions and Estimates of Genetic Gain from Selection

Science.gov (United States)

Gylander, Tim; Hamann, Andreas; Brouard, Jean S.; Thomas, Barb R.

2012-01-01

Background Aspen naturally grows in large, single-species, even-aged stands that regenerate clonally after fire disturbance. This offers an opportunity for an intensive clonal forestry system that closely emulates the natural life history of the species. In this paper, we assess the potential of genetic tree improvement and clonal deployment to enhance the productivity of aspen forests in Alberta. We further investigate geographic patterns of genetic variation in aspen and infer forest management strategies under uncertain future climates. Methodology/Principal Findings Genetic variation among 242 clones from Alberta was evaluated in 13 common garden trials after 5–8 growing seasons in the field. Broad-sense heritabilities for height and diameter at breast height (DBH) ranged from 0.36 to 0.64, allowing 5–15% genetic gains in height and 9–34% genetic gains in DBH. Geographic partitioning of genetic variance revealed predominant latitudinal genetic differentiation. We further observed that northward movement of clones almost always resulted in increased growth relative to local planting material, while southward movement had a strong opposite effect. Conclusion/Significance Aspen forests are an important natural resource in western Canada that is used for pulp and oriented strandboard production, accounting for ∼40% of the total forest harvest. Moderate to high broad-sense heritabilities in growth traits suggest good potential for a genetic tree improvement program with aspen. Significant productivity gains appear possible through clonal selection from existing trials. We propose two breeding regions for Alberta, and suggest that well-tested southern clones may be used in the northern breeding region, accounting for a general warming trend observed over the last several decades in Alberta. PMID:22957006

Tree Hazards Recognition and Reduction in Recreation Sites

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David W. Johnson

1981-01-01

Defective trees are potential hazards to people and property in recreation areas. Most reported tree failures within recreation sites in the Rocky Mountain Region occur in lodgepole pine. Defective root systems account for the greatest percentage of failures. External indicators of defects are used to identify trees that may fail. Some tree species, particularly aspen...

Growth, leaf traits and litter decomposition of roadside hybrid aspen (Populus tremula L. x P. tremuloides Michx.) clones

International Nuclear Information System (INIS)

Nikula, Suvi; Manninen, Sirkku; Vapaavuori, Elina; Pulkkinen, Pertti

2011-01-01

Road traffic contributes considerably to ground-level air pollution and is therefore likely to affect roadside ecosystems. Differences in growth and leaf traits among 13 hybrid aspen (Populus tremula x P. tremuloides) clones were studied in relation to distance from a motorway. The trees sampled were growing 15 and 30 m from a motorway and at a background rural site in southern Finland. Litter decomposition was also measured at both the roadside and rural sites. Height and diameter growth rate and specific leaf area were lowest, and epicuticular wax amount highest in trees growing 15 m from the motorway. Although no significant distance x clone interactions were detected, clone-based analyses indicated differences in genotypic responses to motorway proximity. Leaf N concentration did not differ with distance from the motorway for any of the clones. Leaf litter decomposition was only temporarily retarded in the roadside environment, suggesting minor effects on nutrient cycling. - Highlights: → Roadside hybrid aspen displayed xeromorphic leaf traits and reduction in growth rate. → These responses were limited to trees close to the motorway and only to some clones. → Leaf litter decomposition was only temporarily retarded in the roadside environment. - Hybrid aspen had more xeromorphic leaves, displayed reduced growth, and showed retarded litter decomposition at an early stage in the roadside environment.

Transcriptome responses to aluminum stress in roots of aspen (Populus tremula

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Grisel Nadine

2010-08-01

Full Text Available Abstract Background Ionic aluminum (mainly Al3+ is rhizotoxic and can be present in acid soils at concentrations high enough to inhibit root growth. Many forest tree species grow naturally in acid soils and often tolerate high concentrations of Al. Previously, we have shown that aspen (Populus tremula releases citrate and oxalate from roots in response to Al exposure. To obtain further insights into the root responses of aspen to Al, we investigated root gene expression at Al conditions that inhibit root growth. Results Treatment of the aspen roots with 500 μM Al induced a strong inhibition of root growth within 6 h of exposure time. The root growth subsequently recovered, reaching growth rates comparable to that of control plants. Changes in gene expression were determined after 6 h, 2 d, and 10 d of Al exposure. Replicated transcriptome analyses using the Affymetrix poplar genome array revealed a total of 175 significantly up-regulated and 69 down-regulated genes, of which 70% could be annotated based on Arabidopsis genome resources. Between 6 h and 2 d, the number of responsive genes strongly decreased from 202 to 26, and then the number of changes remained low. The responses after 6 h were characterized by genes involved in cell wall modification, ion transport, and oxidative stress. Two genes with prolonged induction were closely related to the Arabidopsis Al tolerance genes ALS3 (for Al sensitive 3 and MATE (for multidrug and toxin efflux protein, mediating citrate efflux. Patterns of expression in different plant organs and in response to Al indicated that the two aspen genes are homologs of the Arabidopsis ALS3 and MATE. Conclusion Exposure of aspen roots to Al results in a rapid inhibition of root growth and a large change in root gene expression. The subsequent root growth recovery and the concomitant reduction in the number of responsive genes presumably reflect the success of the roots in activating Al tolerance mechanisms. The

Landscape dynamics of aspen and conifer forests

Science.gov (United States)

Dale L. Bartos

2001-01-01

Quaking aspen (Populus tremuloides Michx.) is widely dispersed across the landscape of North America. Seventy-five percent of the aspen in the western United States occurs in the states of Colorado (50%) and Utah (25%). Reproduction in aspen is primarily by asexual means, e.g., root sprouts that are generally referred to as suckers. An aspen clone consists of numerous...

Heavy metals uptake by the hybrid aspen and rowan-tree clones

Czech Academy of Sciences Publication Activity Database

Malá, J.; Máchová, P.; Cvrčková, H.; Vaněk, Tomáš

2007-01-01

Roč. 53, č. 11 (2007), s. 491-497 ISSN 1212-4834 R&D Projects: GA ČR GA526/04/0135; GA MŠk 2B06187 Grant - others:Výzkumný ústav lesního hospodářství a myslivosti, v.v (CZ) OC 118 Institutional research plan: CEZ:AV0Z50380511 Source of funding: V - iné verejné zdroje ; V - iné verejné zdroje Keywords : phytoremediation * heavy metals * hybrid aspen Subject RIV: EB - Genetics ; Molecular Biology http://journals.uzpi.cz:8050/uniqueFiles/00437.pdf

Climatic Sensitivity of a Mixed Forest Association of White Spruce and Trembling Aspen at Their Southern Range Limit

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Sophan Chhin

2016-10-01

Full Text Available Climatic sensitivity of white spruce (Picea glauca (Moench Voss was examined growing in association with trembling aspen (Populus tremuloides Michx. at their southern limit of distribution in a transitional ecotone between the southern boreal forest and northern prairie region. The study was carried out in the Spruce Woods Provincial Park (SWPP located in southwestern Manitoba, Canada. The dry regional climate restricted trembling aspen growth during the growing season via moisture deficiency and temperature induced drought stress. Warm, mild winters also negatively affected radial growth of trembling aspen. Growth of white spruce was moderated by conditions within the aspen stands as radial growth patterns showed low variability from year to year, a low common growth signal, and a stronger response to temperature than to precipitation. Nonetheless, the dry regional climate still restricted growth of white spruce during the growing season via temperature induced drought stress. The findings of the study for white spruce support the stress gradient hypothesis in which facilitative interactions between tree species are expected under harsher environmental conditions.

Gibberellins inhibit adventitious rooting in hybrid aspen and Arabidopsis by affecting auxin transport.

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Mauriat, Mélanie; Petterle, Anna; Bellini, Catherine; Moritz, Thomas

2014-05-01

Knowledge of processes involved in adventitious rooting is important to improve both fundamental understanding of plant physiology and the propagation of numerous plants. Hybrid aspen (Populus tremula × tremuloïdes) plants overexpressing a key gibberellin (GA) biosynthesis gene (AtGA20ox1) grow rapidly but have poor rooting efficiency, which restricts their clonal propagation. Therefore, we investigated the molecular basis of adventitious rooting in Populus and the model plant Arabidopsis. The production of adventitious roots (ARs) in tree cuttings is initiated from the basal stem region, and involves the interplay of several endogenous and exogenous factors. The roles of several hormones in this process have been characterized, but the effects of GAs have not been fully investigated. Here, we show that a GA treatment negatively affects the numbers of ARs produced by wild-type hybrid aspen cuttings. Furthermore, both hybrid aspen plants and intact Arabidopsis seedlings overexpressing AtGA20ox1, PttGID1.1 or PttGID1.3 genes (with a 35S promoter) produce few ARs, although ARs develop from the basal stem region of hybrid aspen and the hypocotyl of Arabidopsis. In Arabidopsis, auxin and strigolactones are known to affect AR formation. Our data show that the inhibitory effect of GA treatment on adventitious rooting is not mediated by perturbation of the auxin signalling pathway, or of the strigolactone biosynthetic and signalling pathways. Instead, GAs appear to act by perturbing polar auxin transport, in particular auxin efflux in hybrid aspen, and both efflux and influx in Arabidopsis. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

Root growth and physiology of potted and field-grown trembling aspen exposed to tropospheric ozone

Science.gov (United States)

M.D. Coleman; R.E. Dickson; J.G. Isebrands; D.F. Karnosky

1996-01-01

We studied root growth and respiration of potted plants and field-grown aspen trees (Populus tremuloides Michx.) exposed to ambient or twice-ambient ozone. Root dry weight of potted plants decreased up to 45% after 12 weeks of ozone treatment, and root system respiration decreased by 27%. The ozone-induced decrease in root system respiration of...

A single European aspen (Populus tremula) tree individual may potentially harbour dozens of Cenococcum geophilum ITS genotypes and hundreds of species of ectomycorrhizal fungi.

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Bahram, Mohammad; Põlme, Sergei; Kõljalg, Urmas; Tedersoo, Leho

2011-02-01

Ectomycorrhizal fungi (EcMF) form diverse communities and link different host plants into mycorrhizal networks, yet little is known about the magnitude of mycobiont diversity of a single tree individual. This study addresses species richness and spatial structure of EcMF in the root system of a single European aspen (Populus tremula) individual in an old-growth boreal mixed forest ecosystem in Estonia. Combining morphological and molecular identification methods for both plant and fungi, 122 species of EcMF were recovered from 103 root samples of the single tree. Richness estimators predicted the total EcMF richness to range from 182 to 207 species, reflecting the observation of 62.3% singletons and doubletons within the community. Fine-scale genetic diversity in Cenococcum geophilum indicates the presence of 23 internal transcribed spacer genotypes. EcMF community was significantly spatially autocorrelated only at the lineage level up to 3 m distance, but not at the species level. Proximity of other hosts had a significant effect on the spatial distribution of EcMF lineages. This study demonstrates that a single tree may host as many EcMF species and individuals as recovered on multiple hosts in diverse communities over larger areas. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Influence of stocking, site quality, stand age, low-severity canopy disturbance, and forest composition on sub-boreal aspen mixedwood carbon stocks

Science.gov (United States)

Reinikainen, Michael; D’Amato, Anthony W.; Bradford, John B.; Fraver, Shawn

2014-01-01

Low-severity canopy disturbance presumably influences forest carbon dynamics during the course of stand development, yet the topic has received relatively little attention. This is surprising because of the frequent occurrence of such events and the potential for both the severity and frequency of disturbances to increase as a result of climate change. We investigated the impacts of low-severity canopy disturbance and average insect defoliation on forest carbon stocks and rates of carbon sequestration in mature aspen mixedwood forests of varying stand age (ranging from 61 to 85 years), overstory composition, stocking level, and site quality. Stocking level and site quality positively affected the average annual aboveground tree carbon increment (CAAI), while stocking level, site quality, and stand age positively affected tree carbon stocks (CTREE) and total ecosystem carbon stocks (CTOTAL). Cumulative canopy disturbance (DIST) was reconstructed using dendroecological methods over a 29-year period. DIST was negatively and significantly related to soil carbon (CSOIL), and it was negatively, albeit marginally, related to CTOTAL. Minima in the annual aboveground carbon increment of trees (CAI) occurred at sites during defoliation of aspen (Populus tremuloides Michx.) by forest tent caterpillar (Malacosoma disstria Hubner), and minima were more extreme at sites dominated by trembling aspen than sites mixed with conifers. At sites defoliated by forest tent caterpillar in the early 2000s, increased sequestration by the softwood component (Abies balsamea (L.) Mill. and Picea glauca (Moench) Voss) compensated for overall decreases in CAI by 17% on average. These results underscore the importance of accounting for low-severity canopy disturbance events when developing regional forest carbon models and argue for the restoration and maintenance of historically important conifer species within aspen mixedwoods to enhance stand-level resilience to disturbance agents and maintain

Modelling growth-competition relationships in trembling aspen and white spruce mixed boreal forests of Western Canada.

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Huang, Jian-Guo; Stadt, Kenneth J; Dawson, Andria; Comeau, Philip G

2013-01-01

We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA), the sum of stem diameter at breast height (SDBH), and density (N) for the broadleaf and coniferous species, as well as similar indices considering only trees with diameters greater than each subject (BAGR, SDBHGR, and NGR), were evaluated. We used a nonlinear mixed model to characterize the basal area increment over the past 5, 10, 15, 20, 25, 30, and 35 years as a function of growth of nearby dominant trees, the size of the subject trees, deciduous and coniferous competition indices, and ecoregions. SDBHGR and BAGR were better predictors for spruce, and SDBHGR and NGR were better for aspen, respectively, than other indices. Results showed strongest correlations with long-term stem growth, as the best models integrated growth for 10-25 years for aspen and ≥ 25 for spruce. Our model demonstrated a remarkable capability (adjusted R(2)>0.67) to represent this complex variation in growth as a function of site, size and competition.

Modelling growth-competition relationships in trembling aspen and white spruce mixed boreal forests of Western Canada.

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Jian-Guo Huang

Full Text Available We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA, the sum of stem diameter at breast height (SDBH, and density (N for the broadleaf and coniferous species, as well as similar indices considering only trees with diameters greater than each subject (BAGR, SDBHGR, and NGR, were evaluated. We used a nonlinear mixed model to characterize the basal area increment over the past 5, 10, 15, 20, 25, 30, and 35 years as a function of growth of nearby dominant trees, the size of the subject trees, deciduous and coniferous competition indices, and ecoregions. SDBHGR and BAGR were better predictors for spruce, and SDBHGR and NGR were better for aspen, respectively, than other indices. Results showed strongest correlations with long-term stem growth, as the best models integrated growth for 10-25 years for aspen and ≥ 25 for spruce. Our model demonstrated a remarkable capability (adjusted R(2>0.67 to represent this complex variation in growth as a function of site, size and competition.

Ecophysiology of Trembling Aspen in Response to Root-Zone Conditions and Competition on Reclaimed Mine Soil.

Science.gov (United States)

Bockstette, S.; Landhäusser, S.; Pinno, B.; Dyck, M. F.

2014-12-01

Reclaimed soils are typically characterized by increased bulk densities, penetration resistances and poor soil structure as well as associated problems with hydrology and aeration. As a result, available rooting space for planted tree seedlings is often restricted to a shallow layer of topsoil, which is usually of higher quality and is cultivated prior to planting. This may hinder the development of healthy root systems, thus drastically increasing the risk for plant stress by limiting access to soil resources such as water, nutrients and oxygen. These problems are exacerbated when herbaceous plants compete for the same resources within this limited root-zone. To understand how limited rooting space affects the physiology of young trees, we experimentally manipulated soil conditions and levels of competition at a reclaimed mine site in central Alberta, Canada. The site was characterized by heavily compacted, fine textured subsoil (~2.0 Mg ha-1), capped with 15 cm of topsoil (~1.5 Mg ha-1). In a replicated study (n=6) half the plots were treated with a subsoil plow to a depth of about 60 cm to increase available rooting spece. Subsequently, trembling aspen (Populus tremuloides Michx.) and smooth brome (Bromus inermis L.) were planted to create four vegetation covers: aspen (a), brome (b), aspen + brome (ab) and control (c) (no vegetation). Various soil properties, including texture, bulk density, penetration resistance and water availability, in conjunction with plant parameters such as root and shoot growth, leaf area development, sap flow, and stomatal conductance have since been monitored, both in-situ and through destructive sampling. Our results indicate that the soil treatment was effective in lowering bulk densities and penetration resistance, while improving moisture retention characteristics. Tree seedling growth and leaf area development were significantly greater without competition, but did not differ between soil treatments. The soil treatment generally

Repeated Prescribed Burning in Aspen

Science.gov (United States)

Donald A. Perala

1974-01-01

Infrequent burning weather, low flammability of the aspen-hardwood association, and prolific sprouting and seeding of shrubs and hardwoods made repeated dormant season burning a poor tool to convert good site aspen to conifers. Repeat fall burns for wildlife habitat maintenance is workable if species composition changes are not important.

Manipulations to regenerate aspen ecosystems

Science.gov (United States)

Wayne D. Shepperd

2001-01-01

Vegetative regeneration of aspen can be initiated through manipulations that provide hormonal stimulation, proper growth environment, and sucker protection - the three elements of the aspen regeneration triangle. The correct course of action depends upon a careful evaluation of the size, vigor, age, and successional status of the existing clone. Soils and site...

Decay of aspen in Colorado

Science.gov (United States)

Ross W. Davidson; Thomas E. Hinds; Frank G. Hawksworth

1959-01-01

Quaking aspen (Populus tremuloides Michx.) stands are extensive in the central Rocky Mountains. The species reaches its maximum development in the mountains and high mesas west of the Continental Divide in Colorado (Baker, 1925). On the better sites aspen yields a greater volume of wood in a shorter period than most of the conifers growing at comparable elevations. The...

Widespread triploidy in Western North American aspen (Populus tremuloides.

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Karen E Mock

Full Text Available We document high rates of triploidy in aspen (Populus tremuloides across the western USA (up to 69% of genets, and ask whether the incidence of triploidy across the species range corresponds with latitude, glacial history (as has been documented in other species, climate, or regional variance in clone size. Using a combination of microsatellite genotyping, flow cytometry, and cytology, we demonstrate that triploidy is highest in unglaciated, drought-prone regions of North America, where the largest clone sizes have been reported for this species. While we cannot completely rule out a low incidence of undetected aneuploidy, tetraploidy or duplicated loci, our evidence suggests that these phenomena are unlikely to be significant contributors to our observed patterns. We suggest that the distribution of triploid aspen is due to a positive synergy between triploidy and ecological factors driving clonality. Although triploids are expected to have low fertility, they are hypothesized to be an evolutionary link to sexual tetraploidy. Thus, interactions between clonality and polyploidy may be a broadly important component of geographic speciation patterns in perennial plants. Further, cytotypes are expected to show physiological and structural differences which may influence susceptibility to ecological factors such as drought, and we suggest that cytotype may be a significant and previously overlooked factor in recent patterns of high aspen mortality in the southwestern portion of the species range. Finally, triploidy should be carefully considered as a source of variance in genomic and ecological studies of aspen, particularly in western U.S. landscapes.

Acute O3 damage on first year coppice sprouts of aspen and maple sprouts in an open-air experiment

Science.gov (United States)

Joseph N.T. Darbah; Wendy S. Jones; Andrew J. Burton; John Nagy; Mark E. Kubiske

2011-01-01

We studied the effect of high ozone (O3) concentration (110-490 nmol mol-1) on regenerating aspen (Populus tremuloides) and maple (Acer saccharum) trees at an open-air O3 pollution experiment near Rhinelander WI USA. This study is the first of its kind to examine...

Aspen Delineation - Inyo National Forest [ds366

Data.gov (United States)

California Natural Resource Agency — The database represents delineations of known aspen stands where aspen assessments were collected in the Inyo National Forest, Inyo County, California. The Inyo...

Aspen Delineation - Klamath National Forest [ds370

Data.gov (United States)

California Natural Resource Agency — The database represents polygons of aspen stands in the Klamath National Forest, Siskiyou County, California. The Klamath National Forest Region 5 Vegetation aspen...

Aspen Delineation - Sierra State Parks [ds380

Data.gov (United States)

California Natural Resource Agency — The database represents delineations of aspen stands associated with stand assessment data (SIERRA_SP_PTS) collected in aspen stands on lands administered by the...

Aspen Delineation - Sequoia National Forest [ds378

Data.gov (United States)

California Natural Resource Agency — The database represents delineations of aspen stands associated with stand assessment data (SEQUOIA_NF_PTS) collected in aspen stands in the Cannell Meadows Ranger...

Quantitative Evaluation of Hybrid Aspen Xylem and Immunolabeling Patterns Using Image Analysis and Multivariate Statistics

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David Sandquist

2015-06-01

Full Text Available A new method is presented for quantitative evaluation of hybrid aspen genotype xylem morphology and immunolabeling micro-distribution. This method can be used as an aid in assessing differences in genotypes from classic tree breeding studies, as well as genetically engineered plants. The method is based on image analysis, multivariate statistical evaluation of light, and immunofluorescence microscopy images of wood xylem cross sections. The selected immunolabeling antibodies targeted five different epitopes present in aspen xylem cell walls. Twelve down-regulated hybrid aspen genotypes were included in the method development. The 12 knock-down genotypes were selected based on pre-screening by pyrolysis-IR of global chemical content. The multivariate statistical evaluations successfully identified comparative trends for modifications in the down-regulated genotypes compared to the unmodified control, even when no definitive conclusions could be drawn from individual studied variables alone. Of the 12 genotypes analyzed, three genotypes showed significant trends for modifications in both morphology and immunolabeling. Six genotypes showed significant trends for modifications in either morphology or immunocoverage. The remaining three genotypes did not show any significant trends for modification.

Aspen Delineation - Lassen National Forest [ds372

Data.gov (United States)

California Natural Resource Agency — The database represents delineations of aspen stands associated with stand assessment data (LASSEN_NF_EAGLELAKE_PTS) collected in aspen stands in the in the Eagle...

Moderation of [CO2]-induced gas exchange responses by elevated tropospheric O3 in trembling aspen and sugar maple

Science.gov (United States)

Pooja Sharma; Anu Sober; Jaak Sober; Gopi P. Podila; Mark E. Kubiske; William J. Mattson; Judson G. Isebrands; David F. Karnosky

2003-01-01

The greenhouse gases CO2 and 03 are increasing in the earth's atmosphere. Little is known about long-term impacts of these two co-occurring gases on forest trees. We have been examining the impacts of these two gases on the physiology and growth of trembling aspen (Populus tremuloides) and sugar...

Changes in avian and plant communities of aspen woodlands over 12 years after livestock removal in the northwestern Great Basin

Science.gov (United States)

Earnst, Susan L.; Dobkin, David S.; Ballard, Jennifer A.

2012-01-01

Riparian and quaking aspen (Populus tremuloides) woodlands are centers of avian abundance and diversity in the western United States, but they have been affected adversely by land use practices, particularly livestock grazing. In 1990, cattle were removed from a 112,500-ha national wildlife refuge in southeastern Oregon. Thereafter, we monitored changes in vegetation and bird abundance in years 1–3 (phase 1) and 10–12 (phase 2) in 17 riparian and 9 snow-pocket aspen plots. On each 1.5-ha plot, we sampled vegetation in 6 transects. Three times during each breeding season, observers recorded all birds 50 m to each side of the plot's 150-m centerline for 25 minutes. We analyzed data with multivariate analysis of variance and paired t tests with p values adjusted for multiple comparisons. In both periods, riparian and snow-pocket aspen produced extensive regeneration of new shoots (x̄ = 2646 stems/ha and 7079 stems/ha, respectively). By phase 2, a 64% increase in medium-diameter trees in riparian stands indicated successful recruitment into the overstory, but this pattern was not seen in snow-pocket stands, where the density of trees was over 2 times greater. By phase 2 in riparian and snow-pocket stands, native forb cover had increased by 68% and 57%, respectively, mesic shrub cover had increased by 29% and 58%, and sagebrush cover had decreased by 24% and 31%. Total avian abundance increased by 33% and 39% in riparian and snow-pocket aspen, respectively, ground or understory nesters increased by 133% and 67% and overstory nesters increased by 34% and 33%. Similarly, ground or understory foragers increased by 25% and 32%, aerial foragers by 55% and 57%, and overstory foragers by 66% and 43%. We interpreted the substantial regeneration of aspen shoots, increased densities of riparian forbs and shrubs, and increased avian abundances as a multitrophic-level response to the total removal of livestock and as substantial movement toward recovery of biological integrity.

Implementing ASPEN on the CRAY computer

International Nuclear Information System (INIS)

Duerre, K.H.; Bumb, A.C.

1981-01-01

This paper describes our experience in converting the ASPEN program for use on our CRAY computers at the Los Alamos National Laboratory. The CRAY computer is two-to-five times faster than a CDC-7600 for scalar operations, is equipped with up to two million words of high-speed storage, and has vector processing capability. Thus, the CRAY is a natural candidate for programs that are the size and complexity of ASPEN. Our approach to converting ASPEN and the conversion problems are discussed, including our plans for optimizing the program. Comparisons of run times for test problems between the CRAY and IBM 370 computer versions are presented

AspenTech shows specific tools for refiners; AspenTech deploie des outils specifiques pour les raffineurs

Energy Technology Data Exchange (ETDEWEB)

Legros, E

2003-10-01

The supplier of integrated softwares AspenTech has organized last May, the 7 in Gelsenkirchen, on the site of the Veba Oel refinery, a seminar 'refining' intended to show the specificities of its products: Hysys, Aspen Utilities, Icarus...About fifty German engineers and responsible persons coming from refining and engineering firms have participated to this studies day. (O.M.)

Contrasting drivers and trends of coniferous and deciduous tree growth in interior Alaska.

Science.gov (United States)

Cahoon, Sean M P; Sullivan, Patrick F; Brownlee, Annalis H; Pattison, Robert R; Andersen, Hans-Erik; Legner, Kate; Hollingsworth, Teresa N

2018-03-22

The boreal biome represents approximately one third of the world's forested area and plays an important role in global biogeochemical and energy cycles. Numerous studies in boreal Alaska have concluded that growth of black and white spruce is declining as a result of temperature-induced drought stress. The combined evidence of declining spruce growth and changes in the fire regime that favor establishment of deciduous tree species has led some investigators to suggest the region may be transitioning from dominance by spruce to dominance by deciduous forests and/or grasslands. Although spruce growth trends have been extensively investigated, few studies have evaluated long-term radial growth trends of the dominant deciduous species (Alaska paper birch and trembling aspen) and their sensitivity to moisture availability. We used a large and spatially extensive sample of tree cores from interior Alaska to compare long-term growth trends among contrasting tree species (white and black spruce vs. birch and aspen). All species showed a growth peak in the mid-1940s, although growth following the peak varied strongly across species. Following an initial decline from the peak, growth of white spruce showed little evidence of a trend, while black spruce and birch growth showed slight growth declines from ~1970 to present. Aspen growth was much more variable than the other species and showed a steep decline from ~1970 to present. Growth of birch, black and white spruce was sensitive to moisture availability throughout most of the tree-ring chronologies, as evidenced by negative correlations with air temperature and positive correlations with precipitation. However, a positive correlation between previous July precipitation and aspen growth disappeared in recent decades, corresponding with a rise in the population of the aspen leaf miner (Phyllocnistis populiella), an herbivorous moth, which may have driven growth to a level not seen since the early 20th century. Our results

Drought's legacy: multiyear hydraulic deterioration underlies widespread aspen forest die-off and portends increased future risk.

Science.gov (United States)

Anderegg, William R L; Plavcová, Lenka; Anderegg, Leander D L; Hacke, Uwe G; Berry, Joseph A; Field, Christopher B

2013-04-01

Forest mortality constitutes a major uncertainty in projections of climate impacts on terrestrial ecosystems and carbon-cycle feedbacks. Recent drought-induced, widespread forest die-offs highlight that climate change could accelerate forest mortality with its diverse and potentially severe consequences for the global carbon cycle, ecosystem services, and biodiversity. How trees die during drought over multiple years remains largely unknown and precludes mechanistic modeling and prediction of forest die-off with climate change. Here, we examine the physiological basis of a recent multiyear widespread die-off of trembling aspen (Populus tremuloides) across much of western North America. Using observations from both native trees while they are dying and a rainfall exclusion experiment on mature trees, we measure hydraulic performance over multiple seasons and years and assess pathways of accumulated hydraulic damage. We test whether accumulated hydraulic damage can predict the probability of tree survival over 2 years. We find that hydraulic damage persisted and increased in dying trees over multiple years and exhibited few signs of repair. This accumulated hydraulic deterioration is largely mediated by increased vulnerability to cavitation, a process known as cavitation fatigue. Furthermore, this hydraulic damage predicts the probability of interyear stem mortality. Contrary to the expectation that surviving trees have weathered severe drought, the hydraulic deterioration demonstrated here reveals that surviving regions of these forests are actually more vulnerable to future droughts due to accumulated xylem damage. As the most widespread tree species in North America, increasing vulnerability to drought in these forests has important ramifications for ecosystem stability, biodiversity, and ecosystem carbon balance. Our results provide a foundation for incorporating accumulated drought impacts into climate-vegetation models. Finally, our findings highlight the

Growing Season Conditions Mediate the Dependence of Aspen on Redistributed Snow Under Climate Change.

Science.gov (United States)

Soderquist, B.; Kavanagh, K.; Link, T. E.; Seyfried, M. S.; Strand, E. K.

2016-12-01

Precipitation regimes in many semiarid ecosystems are becoming increasingly dominated by winter rainfall as a result of climate change. Across these regions, snowpack plays a vital role in the distribution and timing of soil moisture availability. Rising temperatures will result in a more uniform distribution of soil moisture, advanced spring phenology, and prolonged growing seasons. Productive and wide ranging tree species like aspen, Populus tremuloides, may experience increased vulnerability to drought and mortality resulting from both reduced snowpack and increased evaporative demand during the growing season. We simulated the net primary production (NPP) of aspen stands spanning the rain:snow transition zone in the Reynolds Creek Critical Zone Observatory (RCCZO) in southwest Idaho, USA. Within the RCCZO, the total amount of precipitation has remained unchanged over the past 50 years, however the percentage of the precipitation falling as snow has declined by approximately 4% per decade at mid-elevation sites. The biogeochemical process model Biome-BGC was used to simulate aspen NPP at three stands located directly below snowdrifts that provide melt water late into the spring. After adjusting precipitation inputs to account for the redistribution of snow, we assessed climate change impacts on future aspen productivity. Mid-century (2046-2065) aspen NPP was simulated using temperature projections from a multi-model average under high emission conditions using the Multivariate Adaptive Constructed Analogs (MACA) data set. While climate change simulations indicated over a 20% decrease in annual NPP for some years, NPP rates for other mid-century years remained relatively unchanged due to variations in growing season conditions. Mid-century years with the largest decreases in NPP typically showed increased spring transpiration rates resulting from earlier leaf flush combined with warmer spring conditions. During these years, the onset of drought stress occurred

Aspen Delineation - Klamath National Forest, EUI [ds368

Data.gov (United States)

California Natural Resource Agency — The database represents delineations of known aspen stands where aspen assessments were collected in the Klamath National Forest, Siskiyou County, California. The...

Aspen Delineation - Plumas National Forest, FRRD [ds376

Data.gov (United States)

California Natural Resource Agency — The database represents delineations of aspen stands associated with stand assessment data (PLUMAS_NF_FEATHERRIVER_PTS) collected in aspen stands in the Plumas...

New exposure-based metric approach for evaluating O3 risk to North American aspen forests

International Nuclear Information System (INIS)

Percy, K.E.; Nosal, M.; Heilman, W.; Dann, T.; Sober, J.; Legge, A.H.; Karnosky, D.F.

2007-01-01

The United States and Canada currently use exposure-based metrics to protect vegetation from O 3 . Using 5 years (1999-2003) of co-measured O 3 , meteorology and growth response, we have developed exposure-based regression models that predict Populus tremuloides growth change within the North American ambient air quality context. The models comprised growing season fourth-highest daily maximum 8-h average O 3 concentration, growing degree days, and wind speed. They had high statistical significance, high goodness of fit, include 95% confidence intervals for tree growth change, and are simple to use. Averaged across a wide range of clonal sensitivity, historical 2001-2003 growth change over most of the 26 M ha P. tremuloides distribution was estimated to have ranged from no impact (0%) to strong negative impacts (-31%). With four aspen clones responding negatively (one responded positively) to O 3 , the growing season fourth-highest daily maximum 8-h average O 3 concentration performed much better than growing season SUM06, AOT40 or maximum 1 h average O 3 concentration metrics as a single indicator of aspen stem cross-sectional area growth. - A new exposure-based metric approach to predict O 3 risk to North American aspen forests has been developed

Evaluation of burned aspen communities in Jackson Hole, Wyoming

Science.gov (United States)

Charles E. Kay

2001-01-01

Aspen has been declining in Jackson Hole for many years, a condition generally attributed to the fact that lightning fires have been aggressively suppressed since the early 1900s. It is also believed that burning will successfully regenerate aspen stands despite high elk numbers. To test this hypothesis, I evaluated 467 burned and 495 adjacent, unburned aspen stands at...

Biomass production in forest plantations used as raw material for industry and energy. Final report. Biomasseproduktion in forstlichen Plantagen fuer die Rohstoff- und Energiegewinnung. Schlussbericht

Energy Technology Data Exchange (ETDEWEB)

Ahuja, M.R.; Muhs, H.J.

1986-10-01

European aspen (Populus tremula), quaking aspen (Populus tremuloides), and their hybrids (hybrid aspen) are short-rotation, fast growing forest tree species, that apparently hold potential for biomass and energy production. Because of inherent difficulties in vegetative propagation in aspen, it has not been possible to propagate selected aspen and hybrid aspen tress on a large scale. Therefore, the aim of this project was to develop unconventional methods of vegetative propagation in aspen that can easily be adapted to nursery practices and are also cost-effective. Explants from buds, leaves, stems, and roots were cultured on a modified Woody Plant Medium for the purposes of microvegetative propagation. Protoplasts were also cultured for regenerative studies. Mainly the bud explants were employed for microvegetative propagation. A 2-step micropropagation method, which is commmercially feasible, has been developed for aspen. This method involves: (1) culture of bud explants on a medium for bud conditioning and microshoot proliferation, and (2) rooting of microshoots in peat-perlite mix. By employing this 2-step micropropagation method, several thousand plants have been regenerated from about 50 mature selected aspen and hybrid aspen trees ranging from 1 to 40 years of age. Following transfer to field conditions, tissue culture derived plants exhibited vigorous growth and attained a height of 1.5-2 meters in the first growing season. (orig.) With 23 refs., 1 tab., 20 figs.

Fast growing aspens in the development of a plant micropropagation system based on plant-produced ethylene action

International Nuclear Information System (INIS)

Žiauka, Jonas; Kuusienė, Sigutė; Šilininkas, Mindaugas

2013-01-01

Representatives of the genus Populus (poplars), such as Populus tremula L. (European aspen) and its fast-growing hybrids, are recognized as being among the most suitable tree species for short rotation coppicing in Northern Europe. Several technologies have been developed for fast propagation of selected aspen genotypes, including laboratory (in vitro) micropropagation, which is usually based on the action of exogenous plant hormones. Seeking to minimize the use of the latter, the present study was designed to test if the conditions suitable for increased accumulation of plant-produced gas, including the gaseous plant hormone ethylene, inside a culture vessel could contribute to commercially desirable changes in aspen development. Shoot cultures of several European and hybrid (Populus tremuloides Michx. × P. tremula) aspen genotypes were studied using two different types of culture vessels: tightly sealed Petri dishes (15 × 54 mm) designed to provide restricted gas exchange (RGE) conditions, and capped (but not sealed) test tubes (150 × 18 mm) providing control conditions. Under RGE conditions, not only the positive impact of the ethylene precursors 1-aminocyclopropane-1-carboxylic-acid (ACC) and ethephon on shoot proliferation was demonstrated but also a several-fold increase, compared to the control conditions, in the mean shoot number per explant was recorded even on the hormone-free nutrient medium. Moreover, the shoots developed under RGE conditions were distinguished by superior rooting ability in the subsequent culture. These results suggest that a plant micropropagation system based on the action of plant-produced ethylene rather than of exogenous hormones is possible. -- Highlights: ► Aspen in vitro cultures were grown in different vessels. ► Small-volume vessels were used for restriction of gas exchange. ► Aspen explants produced most shoots in small-volume vessels. ► Shoot proliferation was increased due to explant response to ethylene. �

Impact of Canopy Coupling on Canopy Average Stomatal Conductance Across Seven Tree Species in Northern Wisconsin

Science.gov (United States)

Ewers, B. E.; Mackay, D. S.; Samanta, S.; Ahl, D. E.; Burrows, S. S.; Gower, S. T.

2001-12-01

Land use changes over the last century in northern Wisconsin have resulted in a heterogeneous landscape composed of the following four main forest types: northern hardwoods, northern conifer, aspen/fir, and forested wetland. Based on sap flux measurements, aspen/fir has twice the canopy transpiration of northern hardwoods. In addition, daily transpiration was only explained by daily average vapor pressure deficit across the cover types. The objective of this study was to determine if canopy average stomatal conductance could be used to explain the species effects on tree transpiration. Our first hypothesis is that across all of the species, stomatal conductance will respond to vapor pressure deficit so as to maintain a minimum leaf water potential to prevent catostrophic cavitiation. The consequence of this hypothesis is that among species and individuals there is a proportionality between high stomatal conductance and the sensitivity of stomatal conductance to vapor pressure deficit. Our second hypothesis is that species that do not follow the proportionality deviate because the canopies are decoupled from the atmosphere. To test our two hypotheses we calculated canopy average stomatal conductance from sap flux measurements using an inversion of the Penman-Monteith equation. We estimated the canopy coupling using a leaf energy budget model that requires leaf transpiration and canopy aerodynamic conductance. We optimized the parameters of the aerodynamic conductance model using a Monte Carlo technique across six parameters. We determined the optimal model for each species by selecting parameter sets that resulted in the proportionality of our first hypothesis. We then tested the optimal energy budget models of each species by comparing leaf temperature and leaf width predicted by the models to measurements of each tree species. In red pine, sugar maple, and trembling aspen trees under high canopy coupling conditions, we found the hypothesized proportionality

Aquatic ecosystem response to timber harvesting for the purpose of restoring aspen.

Directory of Open Access Journals (Sweden)

Bobette E Jones

Full Text Available The removal of conifers through commercial timber harvesting has been successful in restoring aspen, however many aspen stands are located near streams, and there are concerns about potential aquatic ecosystem impairment. We examined the effects of management-scale conifer removal from aspen stands located adjacent to streams on water quality, solar radiation, canopy cover, temperature, aquatic macroinvertebrates, and soil moisture. This 8-year study (2003-2010 involved two projects located in Lassen National Forest. The Pine-Bogard Project consisted of three treatments adjacent to Pine and Bogard Creeks: (i Phase 1 in January 2004, (ii Phase 2 in August 2005, and (iii Phase 3 in January 2008. The Bailey Project consisted of one treatment adjacent to Bailey Creek in September 2006. Treatments involved whole tree removal using track-laying harvesters and rubber tire skidders. More than 80% of all samples analyzed for NO₃-N, NH₄-N, and PO₄-P at Pine, Bogard, and Bailey Creeks were below the detection limit, with the exception of naturally elevated PO₄-P in Bogard Creek. All nutrient concentrations (NO₃-N, NH₄-N, PO₄-P, K, and SO₄-S showed little variation within streams and across years. Turbidity and TSS exhibited annual variation, but there was no significant increase in the difference between upstream and downstream turbidity and TSS levels. There was a significant decrease in stream canopy cover and increase in the potential fraction of solar radiation reaching the streams in response to the Pine-Bogard Phase 3 and Bailey treatments; however, there was no corresponding increase in stream temperatures. Macroinvertebrate metrics indicated healthy aquatic ecosystem conditions throughout the course of the study. Lastly, the removal of vegetation significantly increased soil moisture in treated stands relative to untreated stands. These results indicate that, with careful planning and implementation of site-specific best management

Aspen biology, community classification, and management in the Blue Mountains

Science.gov (United States)

David K. Swanson; Craig L. Schmitt; Diane M. Shirley; Vicky Erickson; Kenneth J. Schuetz; Michael L. Tatum; David C. Powell

2010-01-01

Quaking aspen (Populus tremuloides Michx.) is a valuable species that is declining in the Blue Mountains of northeastern Oregon. This publication is a compilation of over 20 years of aspen management experience by USDA Forest Service workers in the Blue Mountains. It includes a summary of aspen biology and occurrence in the Blue Mountains, and a...

ASPEN simulation of cogeneration plants

Energy Technology Data Exchange (ETDEWEB)

Ligang Zheng [CANMET Energy Technology Center, Natural Resources Canada, Nepean, ONT (Canada); Furimsky, E. [IMAG Group, Ottawa, ONT (Canada)

2003-07-01

A detailed flow sheet of the combined cycle cogeneration plant fuelled by natural gas was prepared. The model for simulation of this plant was developed using the ASPEN PLUS software. The results generated using this model were compared with the operating data of the commercial plant generating about 43.6 MW of electricity by gas turbine and 28.6 MW of electricity by steam turbine. The electricity is supplied to the grid, whereas the low pressure steam is utilised locally for heating purposes. The key data generated using the ASPEN model are in good agreement with the operating data. (author)

ASPEN simulation of cogeneration plants

Energy Technology Data Exchange (ETDEWEB)

Zheng Ligang E-mail: lzheng@nrcan.gc.ca; Furimsky, Edward

2003-07-01

A detailed flow sheet of the combined cycle cogeneration plant fuelled by natural gas was prepared. The model for simulation of this plant was developed using the ASPEN PLUS software. The results generated using this model were compared with the operating data of the commercial plant generating about 43.6 MW of electricity by gas turbine and 28.6 MW of electricity by steam turbine. The electricity is supplied to the grid, whereas the low pressure steam is utilised locally for heating purposes. The key data generated using the ASPEN model are in good agreement with the operating data.

ASPEN simulation of cogeneration plants

International Nuclear Information System (INIS)

Zheng Ligang; Furimsky, Edward

2003-01-01

A detailed flow sheet of the combined cycle cogeneration plant fuelled by natural gas was prepared. The model for simulation of this plant was developed using the ASPEN PLUS software. The results generated using this model were compared with the operating data of the commercial plant generating about 43.6 MW of electricity by gas turbine and 28.6 MW of electricity by steam turbine. The electricity is supplied to the grid, whereas the low pressure steam is utilised locally for heating purposes. The key data generated using the ASPEN model are in good agreement with the operating data

Tree and shrub expansion over the past 34 years at the tree-line near Abisko, Sweden.

Science.gov (United States)

Rundqvist, Sara; Hedenås, Henrik; Sandström, Anneli; Emanuelsson, Urban; Eriksson, Håkan; Jonasson, Christer; Callaghan, Terry V

2011-09-01

Shrubs and trees are expected to expand in the sub-Arctic due to global warming. Our study was conducted in Abisko, sub-arctic Sweden. We recorded the change in coverage of shrub and tree species over a 32- to 34-year period, in three 50 x 50 m plots; in the alpine-tree-line ecotone. The cover of shrubs and trees (tree stems (> or =3.5 cm) were noted and positions determined. There has been a substantial increase of cover of shrubs and trees, particularly dwarf birch (Betula nana), and mountain birch (Betula pubescens ssp. czerepanovii), and an establishment of aspen (Populus tremula). The other species willows (Salix spp.), juniper (Juniperus communis), and rowan (Sorbus aucuparia) revealed inconsistent changes among the plots. Although this study was unable to identify the causes for the change in shrubs and small trees, they are consistent with anticipated changes due to climate change and reduced herbivory.

Iterative Repair Planning for Spacecraft Operations Using the Aspen System

Science.gov (United States)

Rabideau, G.; Knight, R.; Chien, S.; Fukunaga, A.; Govindjee, A.

2000-01-01

This paper describes the Automated Scheduling and Planning Environment (ASPEN). ASPEN encodes complex spacecraft knowledge of operability constraints, flight rules, spacecraft hardware, science experiments and operations procedures to allow for automated generation of low level spacecraft sequences. Using a technique called iterative repair, ASPEN classifies constraint violations (i.e., conflicts) and attempts to repair each by performing a planning or scheduling operation. It must reason about which conflict to resolve first and what repair method to try for the given conflict. ASPEN is currently being utilized in the development of automated planner/scheduler systems for several spacecraft, including the UFO-1 naval communications satellite and the Citizen Explorer (CX1) satellite, as well as for planetary rover operations and antenna ground systems automation. This paper focuses on the algorithm and search strategies employed by ASPEN to resolve spacecraft operations constraints, as well as the data structures for representing these constraints.

Using inventory data to determine the impact of drought on tree mortality

Science.gov (United States)

Greg C. Liknes; Christopher W. Woodall; Charles H. Perry

2012-01-01

Drought has been the subject of numerous recent studies that hint at an acceleration of tree mortality due to climate change. In particular, a recent global survey of tree mortality events implicates drought as the cause of quaking aspen mortality in Minnesota, USA in 2007. In this study, data from the Forest Inventory and Analysis program of the USDA Forest Service...

Drought stress limits the geographic ranges of two tree species via different physiological mechanisms.

Science.gov (United States)

Anderegg, Leander D L; HilleRisLambers, Janneke

2016-03-01

Range shifts are among the most ubiquitous ecological responses to anthropogenic climate change and have large consequences for ecosystems. Unfortunately, the ecophysiological forces that constrain range boundaries are poorly understood, making it difficult to mechanistically project range shifts. To explore the physiological mechanisms by which drought stress controls dry range boundaries in trees, we quantified elevational variation in drought tolerance and in drought avoidance-related functional traits of a widespread gymnosperm (ponderosa pine - Pinus ponderosa) and angiosperm (trembling aspen - Populus tremuloides) tree species in the southwestern USA. Specifically, we quantified tree-to-tree variation in growth, water stress (predawn and midday xylem tension), drought avoidance traits (branch conductivity, leaf/needle size, tree height, leaf area-to-sapwood area ratio), and drought tolerance traits (xylem resistance to embolism, hydraulic safety margin, wood density) at the range margins and range center of each species. Although water stress increased and growth declined strongly at lower range margins of both species, ponderosa pine and aspen showed contrasting patterns of clinal trait variation. Trembling aspen increased its drought tolerance at its dry range edge by growing stronger but more carbon dense branch and leaf tissues, implying an increased cost of growth at its range boundary. By contrast, ponderosa pine showed little elevational variation in drought-related traits but avoided drought stress at low elevations by limiting transpiration through stomatal closure, such that its dry range boundary is associated with limited carbon assimilation even in average climatic conditions. Thus, the same climatic factor (drought) may drive range boundaries through different physiological mechanisms - a result that has important implications for process-based modeling approaches to tree biogeography. Further, we show that comparing intraspecific patterns of

Using Aspen plus in thermodynamics instruction a step-by-step guide

CERN Document Server

Sandler, Stanley I

2015-01-01

A step-by-step guide for students (and faculty) on the use of Aspen in teaching thermodynamics Used for a wide variety of important engineering tasks, Aspen Plus software is a modeling tool used for conceptual design, optimization, and performance monitoring of chemical processes. After more than twenty years, it remains one of the most popular and powerful chemical engineering simulation programs used both industrially and academically. Using Aspen Plus in Thermodynamics Instruction: A Step by Step Guide introduces the reader to the use of Aspen Plus in courses in thermodynamics. It prov

Aspen in the Sierra Nevada: Regional conservation of a continental species

Science.gov (United States)

Paul C. Rogers; Wayne D. Shepperd; Dale L. Bartos

2007-01-01

Quaking aspen (Populus tremuloides Michx.) a common species in North America, is a minor species in the Sierra Nevada of California. However, the limited coverage of aspen in this area appears to carry a disproportionate biodiversity load: numerous species are dependent on the unique components of aspen forests habitat. Land managers in the region...

Simulation of quaking aspen potential fire behavior in Northern Utah, USA

Science.gov (United States)

R. Justin DeRose; A. Joshua Leffler

2014-01-01

Current understanding of aspen fire ecology in western North America includes the paradoxical characterization that aspen-dominated stands, although often regenerated following fire, are “fire-proof”. We tested this idea by predicting potential fire behavior across a gradient of aspen dominance in northern Utah using the Forest Vegetation Simulator and the Fire and...

Winning and losing tree species of reassembly in Minnesota's mixed and broadleaf forests.

Directory of Open Access Journals (Sweden)

Brice B Hanberry

Full Text Available We examined reassembly of winning and losing tree species, species traits including shade and fire tolerance, and associated disturbance filters and forest ecosystem types due to rapid forest change in the Great Lakes region since 1850. We identified winning and losing species by changes in composition, distribution, and site factors between historical and current surveys in Minnesota's mixed and broadleaf forests. In the Laurentian Mixed Forest, shade-intolerant aspen replaced shade-intolerant tamarack as the most dominant tree species. Fire-tolerant white pine and jack pine decreased, whereas shade-tolerant ashes, maples, and white cedar increased. In the Eastern Broadleaf Forest, fire-tolerant white oaks and red oaks decreased, while shade-tolerant ashes, American basswood, and maples increased. Tamarack, pines, and oaks have become restricted to sites with either wetter or sandier and drier soils due to increases in aspen and shade-tolerant, fire-sensitive species on mesic sites. The proportion of shade-tolerant species increased in both regions, but selective harvest reduced the applicability of functional groups alone to specify winners and losers. Harvest and existing forestry practices supported aspen dominance in mixed forests, although without aspen forestry and with fire suppression, mixed forests will transition to a greater composition of shade-tolerant species, converging to forests similar to broadleaf forests. A functional group framework provided a perspective of winning and losing species and traits, selective filters, and forest ecosystems that can be generalized to other regions, regardless of species identity.

Winning and losing tree species of reassembly in Minnesota's mixed and broadleaf forests.

Science.gov (United States)

Hanberry, Brice B; Palik, Brian J; He, Hong S

2013-01-01

We examined reassembly of winning and losing tree species, species traits including shade and fire tolerance, and associated disturbance filters and forest ecosystem types due to rapid forest change in the Great Lakes region since 1850. We identified winning and losing species by changes in composition, distribution, and site factors between historical and current surveys in Minnesota's mixed and broadleaf forests. In the Laurentian Mixed Forest, shade-intolerant aspen replaced shade-intolerant tamarack as the most dominant tree species. Fire-tolerant white pine and jack pine decreased, whereas shade-tolerant ashes, maples, and white cedar increased. In the Eastern Broadleaf Forest, fire-tolerant white oaks and red oaks decreased, while shade-tolerant ashes, American basswood, and maples increased. Tamarack, pines, and oaks have become restricted to sites with either wetter or sandier and drier soils due to increases in aspen and shade-tolerant, fire-sensitive species on mesic sites. The proportion of shade-tolerant species increased in both regions, but selective harvest reduced the applicability of functional groups alone to specify winners and losers. Harvest and existing forestry practices supported aspen dominance in mixed forests, although without aspen forestry and with fire suppression, mixed forests will transition to a greater composition of shade-tolerant species, converging to forests similar to broadleaf forests. A functional group framework provided a perspective of winning and losing species and traits, selective filters, and forest ecosystems that can be generalized to other regions, regardless of species identity.

Aspen Winter Conferences on High Energy

Energy Technology Data Exchange (ETDEWEB)

None, None

2011-02-12

The 2011 Aspen Winter Conference on Particle Physics was held at the Aspen Center for Physics from February 12 to February 18, 2011. Ninety-four participants from ten countries, and several universities and national labs attended the workshop titled, "New Data From the Energy Frontier." There were 54 formal talks, and a considerable number of informal discussions held during the week. The week's events included a public lecture ("The Hunt for the Elusive Higgs Boson" given by Ben Kilminster from Ohio State University) and attended by 119 members of the public, and a physics cafe geared for high schoolers that is a discussion with physicists. The 2011 Aspen Winter Conference on Astroparticle physics held at the Aspen Center for Physics was "Indirect and Direct Detection of Dark Matter." It was held from February 6 to February 12, 2011. The 70 participants came from 7 countries and attended 53 talks over five days. Late mornings through the afternoon are reserved for informal discussions. In feedback received from participants, it is often these unplanned chats that produce the most excitement due to working through problems with fellow physicists from other institutions and countries or due to incipient collaborations. In addition, Blas Cabrera of Stanford University gave a public lecture titled "What Makes Up Dark Matter." There were 183 members of the general public in attendance. Before the lecture, 45 people attended the physics cafe to discuss dark matter. This report provides the attendee lists, programs, and announcement posters for each event.

Winning and Losing Tree Species of Reassembly in Minnesota’s Mixed and Broadleaf Forests

Science.gov (United States)

Hanberry, Brice B.; Palik, Brian J.; He, Hong S.

2013-01-01

We examined reassembly of winning and losing tree species, species traits including shade and fire tolerance, and associated disturbance filters and forest ecosystem types due to rapid forest change in the Great Lakes region since 1850. We identified winning and losing species by changes in composition, distribution, and site factors between historical and current surveys in Minnesota’s mixed and broadleaf forests. In the Laurentian Mixed Forest, shade-intolerant aspen replaced shade-intolerant tamarack as the most dominant tree species. Fire-tolerant white pine and jack pine decreased, whereas shade-tolerant ashes, maples, and white cedar increased. In the Eastern Broadleaf Forest, fire-tolerant white oaks and red oaks decreased, while shade-tolerant ashes, American basswood, and maples increased. Tamarack, pines, and oaks have become restricted to sites with either wetter or sandier and drier soils due to increases in aspen and shade-tolerant, fire-sensitive species on mesic sites. The proportion of shade-tolerant species increased in both regions, but selective harvest reduced the applicability of functional groups alone to specify winners and losers. Harvest and existing forestry practices supported aspen dominance in mixed forests, although without aspen forestry and with fire suppression, mixed forests will transition to a greater composition of shade-tolerant species, converging to forests similar to broadleaf forests. A functional group framework provided a perspective of winning and losing species and traits, selective filters, and forest ecosystems that can be generalized to other regions, regardless of species identity. PMID:23613911

Molecular tools and aspen management: A primer and prospectus

Science.gov (United States)

Karen E. Mock; Bryce A. Richardson; Paul G. Wolf

2013-01-01

Aspen (Populus tremuloides) isaniconic species in North American landscapes, highly valued for recreation, fiber, wildlife and livestock forage, carbon sequestration, biodiversity, and as a fuelbreak. However, there are rising concerns about the ability of aspen to persist in portions of its range, based on bioclimatic modeling, physiological thresholds and mortality...

Recovering aspen follow changing elk dynamics in Yellowstone: evidence of a trophic cascade?

Science.gov (United States)

Painter, Luke E; Beschta, Robert L; Larsen, Eric J; Ripple, William J

2015-01-01

To investigate the extent and causes of recent quaking aspen (Populus tremuloides) recruitment in northern Yellowstone National Park, we measured browsing intensity and height of young aspen in 87 randomly selected aspen stands in 2012, and compared our results to similar data collected in 1997-1998. We also examined the relationship between aspen recovery and the distribution of Rocky Mountain elk (Cervus elaphus) and bison (Bison bison) on the Yellowstone northern ungulate winter range, using ungulate fecal pile densities and annual elk count data. In 1998, 90% of young aspen were browsed and none were taller-than 200 cm, the height at which aspen begin to escape from elk browsing. In 2012, only 37% in the east and 63% in the west portions of the winter range were browsed, and 65% of stands in the east had young aspen taller than 200 cm. Heights of young aspen were inversely related to browsing intensity, with the least browsing and greatest heights in the eastern portion of the range, corresponding with recent changes in elk density and distribution. In contrast with historical elk distribution (1930s-1990s), the greatest densities of elk recently (2006-2012) have been north of the park boundary (approximately 5 elk/km2), and in the western part of the range (2-4 elk/km2), with relatively few elk in the eastern portion of the range (wolves (Canis lupius) in 1995-1996 played a role in these changing elk population dynamics, interacting with other influences including increased predation by bears (Ursus spp.), competition with an expanding bison population, and shifting patterns of human land use and hunting outside the park. The resulting new aspen recruitment is evidence of a landscape-scale trophic cascade in which a resurgent large carnivore community, combined with other ecological changes, has benefited aspen through effects on ungulate prey.

Adverse Influence of Radio Frequency Background on Trembling Aspen Seedlings: Preliminary Observations

Directory of Open Access Journals (Sweden)

Katie Haggerty

2010-01-01

Full Text Available Numerous incidents of aspen decline have been recorded in North America over the past half century, and incidents of very rapid mortality of aspen clones have been observed in Colorado since 2004. The radio frequency (RF environment of the earth has undergone major changes in the past two centuries due to the development and use of electricity in power and communications applications, and the anthropogenic RF background continues to increase in intensity and complexity. This study suggests that the RF background may have strong adverse effects on growth rate and fall anthocyanin production in aspen, and may be an underlying factor in aspen decline.

The influence of recent climate change on tree height growth differs with species and spatial environment.

Science.gov (United States)

Messaoud, Yassine; Chen, Han Y H

2011-02-16

Tree growth has been reported to increase in response to recent global climate change in controlled and semi-controlled experiments, but few studies have reported response of tree growth to increased temperature and atmospheric carbon dioxide (CO₂) concentration in natural environments. This study addresses how recent global climate change has affected height growth of trembling aspen (Populus tremuloides Michx) and black spruce (Picea mariana Mill B.S.) in their natural environments. We sampled 145 stands dominated by aspen and 82 dominated by spruce over the entire range of their distributions in British Columbia, Canada. These stands were established naturally after fire between the 19th and 20th centuries. Height growth was quantified as total heights of sampled dominant and co-dominant trees at breast-height age of 50 years. We assessed the relationships between 50-year height growth and environmental factors at both spatial and temporal scales. We also tested whether the tree growth associated with global climate change differed with spatial environment (latitude, longitude and elevation). As expected, height growth of both species was positively related to temperature variables at the regional scale and with soil moisture and nutrient availability at the local scale. While height growth of trembling aspen was not significantly related to any of the temporal variables we examined, that of black spruce increased significantly with stand establishment date, the anomaly of the average maximum summer temperature between May-August, and atmospheric CO₂ concentration, but not with the Palmer Drought Severity Index. Furthermore, the increase of spruce height growth associated with recent climate change was higher in the western than in eastern part of British Columbia. This study demonstrates that the response of height growth to recent climate change, i.e., increasing temperature and atmospheric CO₂ concentration, did not only differ with tree species, but

Aspen increase soil moisture, nutrients, organic matter and respiration in Rocky Mountain forest communities.

Science.gov (United States)

Buck, Joshua R; St Clair, Samuel B

2012-01-01

Development and change in forest communities are strongly influenced by plant-soil interactions. The primary objective of this paper was to identify how forest soil characteristics vary along gradients of forest community composition in aspen-conifer forests to better understand the relationship between forest vegetation characteristics and soil processes. The study was conducted on the Fishlake National Forest, Utah, USA. Soil measurements were collected in adjacent forest stands that were characterized as aspen dominated, mixed, conifer dominated or open meadow, which includes the range of vegetation conditions that exist in seral aspen forests. Soil chemistry, moisture content, respiration, and temperature were measured. There was a consistent trend in which aspen stands demonstrated higher mean soil nutrient concentrations than mixed and conifer dominated stands and meadows. Specifically, total N, NO(3) and NH(4) were nearly two-fold higher in soil underneath aspen dominated stands. Soil moisture was significantly higher in aspen stands and meadows in early summer but converged to similar levels as those found in mixed and conifer dominated stands in late summer. Soil respiration was significantly higher in aspen stands than conifer stands or meadows throughout the summer. These results suggest that changes in disturbance regimes or climate scenarios that favor conifer expansion or loss of aspen will decrease soil resource availability, which is likely to have important feedbacks on plant community development.

Interspecific variation in growth responses to tree size, competition and climate of western Canadian boreal mixed forests.

Science.gov (United States)

Jiang, Xinyu; Huang, Jian-Guo; Cheng, Jiong; Dawson, Andria; Stadt, Kenneth J; Comeau, Philip G; Chen, Han Y H

2018-08-01

Tree growth of boreal forest plays an important role on global carbon (C) cycle, while tree growth in the western Canadian boreal mixed forests has been predicted to be negatively affected by regional drought. Individual tree growth can be controlled by many factors, such as competition, climate, tree size and age. However, information about contributions of different factors to tree growth is still limited in this region. In order to address this uncertainty, tree rings of two dominant tree species, trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench.) Voss), were sampled from boreal mixed forest stands distributed across Alberta, Canada. Tree growth rates over different time intervals (10years interval, 1998-2007; 20years interval, 1988-2007; 30years interval, 1978-2007) were calculated to study the effects of different factors (tree size, competition, climate, and age) on tree growth. Results indicated that tree growth of two species were both primarily affected by competition or tree size, while climatic indices showed less effects on tree growth. Growth of trembling aspen was significantly affected by inter- and intraspecific competition, while growth of white spruce was primarily influenced by tree size, followed by competition. Positive relationship was found between growth of white spruce and competition index of coniferous group, suggesting an intraspecific mutualism mechanism within coniferous group. Our results further suggested that competition driven succession was the primary process of forest composition shift in the western Canadian boreal mixed forest. Although drought stress increased tree mortality, decline of stem density under climate change released competition stress of surviving trees, which in turn sustained growth of surviving trees. Therefore, climatic indices showed fewer effects on growth of dominant tree species compared to other factors in our study. Copyright © 2018 Elsevier B.V. All rights reserved.

Mycorrhizal fungi of aspen forests: Natural occurrence and potential applications

Science.gov (United States)

Cathy L. Cripps

2001-01-01

Native mycorrhizal fungi associated with aspen were surveyed on three soil types in the north-central Rocky Mountains. Selected isolates were tested for the ability to enhance aspen seedling growth in vitro. Over 50 species of ectomycorrhizal fungi occur with Populus tremuloides in this region, primarily basidiomycete fungi in the Agaricales. Almost one-third (30%)...

Synergetic hydrothermal co-liquefaction of crude glycerol and aspen wood

DEFF Research Database (Denmark)

Pedersen, Thomas Helmer; Jasiunas, Lukas; Casamassima, Luca

2015-01-01

quality were all invariant to the reaction temperature. By increasing the crude glycerol to aspen wood mass ratio from 0:1 to 3:1, char yield was decreased from 18.3% (only aspen wood) to 3.4%. Furthermore, the biocrude quality in terms of the effective hydrogen-to-carbon ratio (H/Ceff) was significantly...

Defensive effects of extrafloral nectaries in quaking aspen differ with scale.

Science.gov (United States)

Mortensen, Brent; Wagner, Diane; Doak, Patricia

2011-04-01

The effects of plant defenses on herbivory can differ among spatial scales. This may be particularly common with indirect defenses, such as extrafloral nectaries (EFNs), that attract predatory arthropods and are dependent on predator distribution, abundance, and behavior. We tested the defensive effects of EFNs in quaking aspen (Populus tremuloides Michx.) against damage by a specialist herbivore, the aspen leaf miner (Phyllocnistis populiella Cham.), at the scale of individual leaves and entire ramets (i.e., stems). Experiments excluding crawling arthropods revealed that the effects of aspen EFNs differed at the leaf and ramet scales. Crawling predators caused similar reductions in the percent leaf area mined on individual leaves with and without EFNs. However, the extent to which crawling predators increased leaf miner mortality and, consequently, reduced mining damage increased with EFN expression at the ramet scale. Thus, aspen EFNs provided a diffuse defense, reducing damage to leaves across a ramet regardless of leaf-scale EFN expression. We detected lower leaf miner damage and survival unassociated with crawling predators on EFN-bearing leaves, suggesting that direct defenses (e.g., chemical defenses) were stronger on leaves with than without EFNs. Greater direct defenses on EFN-bearing leaves may reduce the probability of losing these leaves and thus weakening ramet-scale EFN defense. Aspen growth was not related to EFN expression or the presence of crawling predators over the course of a single season. Different effects of aspen EFNs at the leaf and ramet scales suggest that future studies may benefit from examining indirect defenses simultaneously at multiple scales.

Aspen: A microsimulation model of the economy

Energy Technology Data Exchange (ETDEWEB)

Basu, N.; Pryor, R.J.; Quint, T.; Arnold, T.

1996-10-01

This report presents, Aspen. Sandia National Laboratories is developing this new agent-based microeconomic simulation model of the U.S. economy. The model is notable because it allows a large number of individual economic agents to be modeled at a high level of detail and with a great degree of freedom. Some features of Aspen are (a) a sophisticated message-passing system that allows individual pairs of agents to communicate, (b) the use of genetic algorithms to simulate the learning of certain agents, and (c) a detailed financial sector that includes a banking system and a bond market. Results from runs of the model are also presented.

Design and simulation of heat exchangers using Aspen HYSYS, and Aspen exchanger design and rating for paddy drying application

Science.gov (United States)

Janaun, J.; Kamin, N. H.; Wong, K. H.; Tham, H. J.; Kong, V. V.; Farajpourlar, M.

2016-06-01

Air heating unit is one of the most important parts in paddy drying to ensure the efficiency of a drying process. In addition, an optimized air heating unit does not only promise a good paddy quality, but also save more for the operating cost. This study determined the suitable and best specifications heating unit to heat air for paddy drying in the LAMB dryer. In this study, Aspen HYSYS v7.3 was used to obtain the minimum flow rate of hot water needed. The resulting data obtained from Aspen HYSYS v7.3 were used in Aspen Exchanger Design and Rating (EDR) to generate heat exchanger design and costs. The designs include shell and tubes and plate heat exchanger. The heat exchanger was designed in order to produce various drying temperatures of 40, 50, 60 and 70°C of air with different flow rate, 300, 2500 and 5000 LPM. The optimum condition for the heat exchanger were found to be plate heat exchanger with 0.6 mm plate thickness, 198.75 mm plate width, 554.8 mm plate length and 11 numbers of plates operating at 5000 LPM air flow rate.

IMPACTS OF INTERACTING ELEVATED ATMOSPHERIC CO2 AND O3 ON THE STRUCTURE AND FUNCTIONING OF A NORTHERN FOREST ECOSYSTEM: OPERATING AND DECOMMISSIONING THE ASPEN FACE PROJECT

Energy Technology Data Exchange (ETDEWEB)

Burton, Andrew J. [Michigan Technological University; Zak, Donald R. [University of Michigan; Kubiske, Mark E. [USDA Forest Service; Pregitzer, Kurt S. [University of Idaho

2014-06-30

Two of the most important and pervasive greenhouse gases driving global change and impacting forests in the U.S. and around the world are atmospheric CO2 and tropospheric O3. As the only free air, large-scale manipulative experiment studying the interaction of elevated CO2 and O3 on forests, the Aspen FACE experiment was uniquely designed to address the long-term ecosystem level impacts of these two greenhouse gases on aspen-birch-maple forests, which dominate the richly forested Lake States region. The project was established in 1997 to address the overarching scientific question: “What are the effects of elevated [CO2] and [O3], alone and in combination, on the structure and functioning of northern hardwood forest ecosystems?” From 1998 through the middle of the 2009 growing season, we examined the interacting effects of elevated CO2 and O3 on ecosystem processes in an aggrading northern forest ecosystem to compare the responses of early-successional, rapid-growing shade intolerant trembling aspen and paper birch to those of a late successional, slower growing shade tolerant sugar maple. Fumigations with elevated CO2 (560 ppm during daylight hours) and O3 (approximately 1.5 x ambient) were conducted during the growing season from 1998 to 2008, and in 2009 through harvest date. Response variables quantified during the experiment included growth, competitive interactions and stand dynamics, physiological processes, plant nutrient status and uptake, tissue biochemistry, litter quality and decomposition rates, hydrology, soil respiration, microbial community composition and respiration, VOC production, treatment-pest interactions, and treatment-phenology interactions. In 2009, we conducted a detailed harvest of the site. The harvest included detailed sampling of a subset of trees by component (leaves and buds, fine branches, coarse branches and stem, coarse roots, fine roots) and excavation of soil to a depth of 1 m. Throughout the experiment, aspen and birch

Metal and nutrient dynamics in decomposing tree litter on a metal contaminated site

International Nuclear Information System (INIS)

Van Nevel, Lotte; Mertens, Jan; Demey, Andreas; De Schrijver, An; De Neve, Stefaan; Tack, Filip M.G.; Verheyen, Kris

2014-01-01

In a forest on sandy, metal polluted soil, we examined effects of six tree species on litter decomposition rates and accompanied changes in metal (Cd, Zn) and nutrient (base cations, N, C) amounts. Decomposition dynamics were studied by means of a litterbag experiment lasting for 30 months. The decomposition peak occurred within the first year for all tree species, except for aspen. During litter decomposition, high metal litter types released part of their accumulated metals, whereas low metal litter types were characterized by a metal enrichment. Base cations, N and C were released from all litter types. Metal release from contaminated litter might involve risks for metal dispersion towards the soil. On the other hand, metal enrichment of uncontaminated litter may be ecologically relevant as it can be easily transported or serve as food source. - Highlights: • Litter decomposition peak occurred within the first year for all tree species, except for aspen. • Base cations, N and C were released from all litter types during decomposition. • Cd and Zn were released from the high metal litter types. • Low metal litter types were characterized by a net Cd and Zn enrichment. • Metal and nutrient releases were reflected in topsoil characteristics. - Litter decomposition rates, as well as enrichment and release dynamics of metals and nutrients in decomposing litter were divergent under the different tree species

Simulating the Dependence of Aspen on Redistributed Snow

Science.gov (United States)

Soderquist, B.; Kavanagh, K.; Link, T. E.; Seyfried, M. S.; Winstral, A. H.

2013-12-01

In mountainous regions across the western USA, the distribution of aspen (Populus tremuloides) is often directly related to heterogeneous soil moisture subsidies resulting from redistributed snow. With decades of climate and precipitation data across elevational and precipitation gradients, the Reynolds Creek Experimental Watershed (RCEW) in southwest Idaho provides a unique opportunity to study the relationship between aspen and redistributed snow. Within the RCEW, the total amount of precipitation has not changed in the past 50 years, but there are sharp declines in the percentage of the precipitation falling as snow. As shifts in the distribution of available moisture continue, future trends in aspen net primary productivity (NPP) remain uncertain. In order to assess the importance of snowdrift subsidies, NPP of three aspen stands was simulated at sites spanning elevational and precipitation gradients using the biogeochemical process model BIOME-BGC. At the aspen site experiencing the driest climate and lowest amount of precipitation from snow, approximately 400 mm of total precipitation was measured from November to March of 2008. However, peak measured snow water equivalent (SWE) held in drifts directly upslope of this stand was approximately 2100 mm, 5 times more moisture than the uniform winter precipitation layer initially assumed by BIOME-BGC. BIOME-BGC simulations in dry years forced by adjusted precipitation data resulted in NPP values approximately 30% higher than simulations assuming a uniform precipitation layer. Using BIOME-BGC and climate data from 1985-2011, the relationship between simulated NPP and measured basal area increments (BAI) improved after accounting for redistributed snow, indicating increased simulation representation. In addition to improved simulation capabilities, soil moisture data, diurnal branch water potential, and stomatal conductance observations at each site detail the use of soil moisture in the rooting zone and the onset

Stand development of trembling aspen in Canaan Valley, West Virginia

Science.gov (United States)

James S. Rentch; James T. Anderson

2008-01-01

In wetlands of Canaan Valley, West Virginia, trembling aspen occurs as a disjunct population well south of its primary natural range. Based on sample data from 15 stands, we found that aspen occurs as nearly monospecific stands or clones. Eight stands had median ages between 30 and 40 yrs, and we suggest that stand initiation was related to changes in land use after...

Lichen community change in response to succession in aspen forests of the southern Rocky Mountains

Science.gov (United States)

Paul C. Rogers; Ronald J. Ryel

2008-01-01

In western North America, quaking aspen (Populus tremuloides) is the most common hardwood in montane landscapes. Fire suppression, grazing and wildlife management practices, and climate patterns of the past century are all potential threats to aspen coverage in this region. If aspen-dependent species are losing habitat, this raises concerns about...

Trembling aspen response to a mixed-severity wildfire in the Black Hills, South Dakota, USA

Science.gov (United States)

Tara L. Keyser; Frederick W. Smith; Wayne D. Shepperd

2005-01-01

Trembling aspen (Populus tremuloides Michx.) regeneration dynamics including sprout production, growth, and clone size were measured to determine the effects of fire on small aspen clone persistence following a mixedseverity wildfire in the Black Hills, South Dakota. Four years postfire, 10 small, isolated aspen clones per low and high fire severity...

Aspen Characteristics - Plumas National Forest [ds373

Data.gov (United States)

California Natural Resource Agency — The database represents point locations and associated stand assessment data collected within aspen stands in the Plumas National Forest, Beckwourth Ranger District...

Aspen Characteristics - Klamath National Forest [ds369

Data.gov (United States)

California Natural Resource Agency — The database represents point locations and associated stand assessment data collected with known aspen stands in the Klamath National Forest, Siskiyou County,...

Aspen Characteristics - Sequoia National Forest [ds377

Data.gov (United States)

California Natural Resource Agency — The database represents point locations and associated stand assessment data collected within aspen stands in the Cannell Meadows Ranger District, Sequoia National...

Effect of Different Tree canopies on the Brightness Temperature of Snowpack

Science.gov (United States)

Mousavi, S.; De Roo, R. D.; Brucker, L.

2017-12-01

Snow stores the water we drink and is essential to grow food that we eat. But changes in snow quantities such as snow water equivalent (SWE) are underway and have serious consequences. So, effective management of the freshwater reservoir requires to monitor frequently (weekly or better) the spatial distribution of SWE and snowpack wetness. Both microwave radar and radiometer systems have long been considered as relevant remote sensing tools in retrieving globally snow physical parameters of interest thanks to their all-weather operation capability. However, their observations are sensitive to the presence of tree canopies, which in turns impacts SWE estimation. To address this long-lasting challenge, we parked a truck-mounted microwave radiometer system for an entire winter in a rare area where it exists different tree types in the different cardinal directions. We used dual-polarization microwave radiometers at three different frequencies (1.4, 19, and 37 GHz), mounted on a boom truck to observe continuously the snowpack surrounding the truck. Observations were recorded at different incidence angles. These measurements have been collected in Grand Mesa National Forest, Colorado as part of the NASA SnowEx 2016-17. In this presentation, the effect of Engelmann Spruce and Aspen trees on the measured brightness temperature of snow is discussed. It is shown that Engelmann Spruce trees increases the brightness temperature of the snowpack more than Aspen trees do. Moreover, the elevation angular dependence of the measured brightness temperatures of snowpack with and without tree canopies is investigated in the context of SWE retrievals. A time-lapse camera was monitoring a snow post installed in the sensors' field of view to characterize the brightness temperature change as snow depth evolved. Also, our study takes advantage of the snowpit measurements that were collected near the radiometers' field of view.

Optimization of composition and technology for tablets containing aspen bark extract

Directory of Open Access Journals (Sweden)

O. I. Onуshkiv

2015-04-01

Full Text Available Summary. Influence of quantitativefactorsof basic quality parameters has been investigated for tabletscontainingextractofaspenbark, receivedbydirect pressingmethodand mathematicalplanningof experiment.To set the optimal composition of tablets containingaspen bark extract the proportion ofProsolv 90, Ludiflash and Polyplasdone XL 10 has been studied. The relationship between the studied factors and parameters of tablets’ regression models has been described. As a result tablets containing aspen bark extractwith mentioned above formula match necessary pharmaco-technological parameters of State Pharmacopoeia of Ukraine. Introduction.Peptic and duodenal ulcer are serious problems in modern medicine. According to statistics this disease is found in 12,83 % of the adult population in Ukraine [1]. Among the remedies for treatment and prevention of peptic ulcers we can find herbal medicines that may be used in the treatment of pre-peptic conditions and during an acute period as a means of adjuvant therapy in combination with strong remedies [2]. An antacid, cytoprotective, anti-inflammatory and reparative actions of aspen bark extract were proved by the researches of domestic and foreign scientists [3, 4]. Previously, we researched the mutual influence of excipients on the main indicators of quality of aspen bark extract tablets obtained by direct compression method. Due to these researches the best excipientshave been selected. It is necessary to establish the optimal quantitative proportion of excipients in order to obtain the tablets with suitable parameters that satisfy the requirements of the State Pharmacopoeia of Ukraine (SPU [5, 6]. Rational selection of excipients requires wide range of studies to obtain the optimal composition of the tablets containing aspen bark extract. Using mathematical planning of the experiment gives the possibility to reduce the number of experiments and to obtain the most detailed results of researches about effects

PERACETIC ACID PRETREATMENT OF ALFALFA STEM AND ASPEN BIOMASS

OpenAIRE

Lei Xu,; Ulrike W. Tschirner

2011-01-01

Alfalfa stems and ground aspen were exposed to peracetic acid (0.5 to 9% on biomass) at temperatures ranging from 40 to 100° C and reaction times from 1 to 5 hours. Glucose release as a percentage of total cellulose content was determined using subsequent standard enzymatic hydrolysis. Statistical analysis confirmed that aspen showed a strong response to peracetic acid addition rate. 9% peracetic acid removed 14% of the original lignin and increased the rate of glucose release from 23% to 44%...

Aspen Characteristics - Lassen National Forest [ds371

Data.gov (United States)

California Natural Resource Agency — The database represents point locations and associated stand assessment data collected in aspen stands in the in the Eagle Lake Ranger District, Lassen National...

Aspen Grupp võitis RKASi / Lemmi Kann

Index Scriptorium Estoniae

Kann, Lemmi

2008-01-01

Ehitusfirma Aspen Grupp OÜ võitis Tallinna ringkonnakohtus Riigi Kinnisvara AS-i, kes diskvalifitseeris ehitusfirma riigihankelt seaduses olnud maksevõlgnevuse keelu tõttu. Vt. samas: Lahendust ootavad veel kaks kohtuasja

Enhanced model for integrated simulation of an entrained bed gasifier implemented as Aspen Hysys extension

Energy Technology Data Exchange (ETDEWEB)

Perez-Fortes, M; Bojarski, A; Ferrer-Nadal, S; Kopanos, G; Mitta, N; Pinilla, C A; Nougues, J M; Velo, E; Puigjaner, L [Universitat Politecnica de Catalunya, Barcelona (Spain). Dept. of Chemical Engineering-CEPIMA

2007-07-01

In this work an enhanced mathematical model of an entrained bed gasifier has been developed for improved synthesis gas production. The gasification model considers five stages: pyrolysis, volatiles combustion, char combustion, gasification and a final gas equilibrium zone. Mathematical simulations are carried out to help finding out feasible operating conditions of the process to achieve improved process performance. Visual Basic (VB) is tested as tool for modelling, by using the Aspen Hysys Extension (AHE) interface standards. This standard provides a suitable environment for this purpose, since it allows the creation of completely custom modules which are easy to plug and use thus facilitating the handling of complex models ready to interact with commercial simulation platforms. In this work, integration of different models is accomplished in Aspen Hysys (AH), which provides the basic connectivity within models components, and the thermodynamic framework needed. The integrated modules simulation environment platform uses data from ELCOGAS for validation purposes with excellent preliminary results. 9 refs., 2 figs.

Dying piece by piece: carbohydrate dynamics in aspen seedlings under severe carbon stress and starvation

Science.gov (United States)

Wiley, Erin; Chow, Pak; Landhäusser, Simon

2016-04-01

Carbon stress and starvation remain poorly understood in trees, despite their potential role in mortality from a variety of agents. To explore the effects of carbon stress on nonstructural carbohydrate (NSC) dynamics and recovery potential and to examine the process of starvation, we grew aspen seedlings under one of three levels of shade: 40% (light shade), 8% (medium shade), and 4% (dark shade) of full sunlight. We then exposed seedlings to 24 hours darkness at either 20° or 28° C until trees had died. Periodically, seedlings were harvested for NSC analysis and to measure stem and root respiration. In addition, some seedlings were moved back into the light to determine if recovery was possible at certain points during starvation. Specifically, we sought to address the following questions: 1) Do NSC concentrations or mass influence tree survival under carbon stress? 2) At what carbohydrate levels do trees fail to recover and starve? 3) Does temperature affect the NSC level at which trees starve? Increasing shade reduced growth, but surprisingly did not reduce NSC levels, except in a portion of deep shade seedlings that experienced dieback. Once in darkness, leaves died first, with final NSC levels ranging from ~4% (Medium shade, 28 degrees) to 7.5% (Light shade). Stem death generally occurred gradually down the stem. Stem tissues retained ~1-2% NSC when dead. Recovery was still possible when only the upper half of the stem had died; at this point, seedlings had relatively high root NSC levels in their remaining roots (7-10%), with 1-3% starch. No trees recovered after the whole stem had died, at which point, some trees root systems were completely dead. However, most retained substantial amounts of live roots, averaging 5-6% NSC, with 0.25-1.5% starch. Despite the initially similar NSC concentrations, light shade seedlings took longer to reach half stem and whole stem death than seedlings from medium and dark shade. Longer survival times were associated with

Aspen SUCROSE TRANSPORTER3 Allocates Carbon into Wood Fibers1[C][W

Science.gov (United States)

Mahboubi, Amir; Ratke, Christine; Gorzsás, András; Kumar, Manoj; Mellerowicz, Ewa J.; Niittylä, Totte

2013-01-01

Wood formation in trees requires carbon import from the photosynthetic tissues. In several tree species, including Populus species, the majority of this carbon is derived from sucrose (Suc) transported in the phloem. The mechanism of radial Suc transport from phloem to developing wood is not well understood. We investigated the role of active Suc transport during secondary cell wall formation in hybrid aspen (Populus tremula × Populus tremuloides). We show that RNA interference-mediated reduction of PttSUT3 (for Suc/H+ symporter) during secondary cell wall formation in developing wood caused thinner wood fiber walls accompanied by a reduction in cellulose and an increase in lignin. Suc content in the phloem and developing wood was not significantly changed. However, after 13CO2 assimilation, the SUT3RNAi lines contained more 13C than the wild type in the Suc-containing extract of developing wood. Hence, Suc was transported into developing wood, but the Suc-derived carbon was not efficiently incorporated to wood fiber walls. A yellow fluorescent protein:PttSUT3 fusion localized to plasma membrane, suggesting that reduced Suc import into developing wood fibers was the cause of the observed cell wall phenotype. The results show the importance of active Suc transport for wood formation in a symplasmically phloem-loading tree species and identify PttSUT3 as a principal transporter for carbon delivery into secondary cell wall-forming wood fibers. PMID:24170204

Aspen Forest Cover by Stratum/Plot (SNF)

Data.gov (United States)

National Aeronautics and Space Administration — Average percent coverage and standard deviation of each canopy stratum from subplots at each aspen site during the SNF study in the Superior National Forest, Minnesota

Understanding the role of the cytoskeleton in wood formation in angiosperm trees: hybrid aspen (Populus tremula x P. tremuloides) as a model species

Energy Technology Data Exchange (ETDEWEB)

Chaffey, N.; Barlow, P. [Bristol Univ., Dept. of Agricultural Sciences, Long Ashton, (United Kingdom); Sundberg, B. [Swedish Univ. of Agricultural Sciences, Dept. of Forest Genetics and Plant Physiology, Umea (Sweden)

2002-03-01

The involvement of microfilaments (MFs) and microtubules (MTs) in the development of the radial and axial components of secondary wood in hybrid aspen (Populus tremula X P. tremuloides) was studied by indirect immunofluorescent localization techniques in order to elucidate a consensus view of the roles of the cytoskeleton during wood formation in angiosperm trees. Early and late vessel elements, axial parenchyma, normal-wood fibres and contact and isolation cells were included in addition to cambial cells. Microfilaments were found to be rare in cambial cells, but were abundant and axially arranged in their derivatives once cell elongation begun. Microtubules were randomly oriented in ray and fusiform cells of the cambial zone. Ellipses of microfilaments were associated with pit development in fiber cells and isolation ray cells. Rings of localized microtubules and microfilaments were associated with developing inter-vessel bordered pits and vessel-contact ray cell contact pits. Although only microtubules were seen in the periphery of the perforation plate of vessel elements, a prominent meshwork of microfilaments overlaid the perforation plate itself. These observations indicate that there are corresponding subcellular control points whose manipulation could lead to the development of 'designer wood'. However, such development would require a better understanding of the physiological basis for the behaviour of microtubule and microfibre cytoskeletons during wood formation. 44 refs., 6 figs.

Predation risk, elk, and aspen: tests of a behaviorally mediated trophic cascade in the Greater Yellowstone Ecosystem.

Science.gov (United States)

Winnie, John A

2012-12-01

Aspen in the Greater Yellowstone Ecosystem are hypothesized to be recovering from decades of heavy browsing by elk due to a behaviorally mediated trophic cascade (BMTC). Several authors have suggested that wolves interact with certain terrain features, creating places of high predation risk at fine spatial scales, and that elk avoid these places, which creates refugia for plants. This hypothesized BMTC could release aspen from elk browsing pressure, leading to a patchy recovery in places of high risk. I tested whether four specific, hypothesized fine-scale risk factors are correlated with changes in current elk browsing pressure on aspen, or with aspen recruitment since wolf reintroduction, in the Daly Creek drainage in Yellowstone National Park, and near two aspen enclosures outside of the park boundary. Aspen were not responding to hypothesized fine-scale risk factors in ways consistent with the current BMTC hypothesis.

Chemical changes to leaf litter from trees grown under elevated CO2 and the implications for microbial utilization in a stream ecosystem

International Nuclear Information System (INIS)

Rier, S. T.; Tuchman, N. C.; Wetzel, R. G.

2005-01-01

The effects of elevated carbon dioxide on the chemistry and subsequent response of stream microorganisms growing on leaf litter of three riparian tree species (quaking aspen, white willow and sugar maple) were studied. Results showed that the effects were species-specific, i.e. aspen leaves contained high concentrations of lignin, maple leafs contained higher concentrations of soluble phenolic compounds and willow leaves contained higher concentrations of carbohydrate-bound condensed tannins. Initially, the higher concentrations of soluble phenolic compounds in maple leaves were rapidly leached in stream water, but overall, the impact of altered leaf chemistry on riparian trees grown under elevated carbon dioxide was clearly variable; no strongly suppressed microbial activity during stream incubation was observed. Any evidence of suppression observed, was species-specific. 49 refs., 2 tabs., 3 figs

Using Aspen simulation package to determine solubility of mixed salts in TRU waste evaporator bottoms

Energy Technology Data Exchange (ETDEWEB)

Hatchell, J.L.

1998-03-01

Nitric acid from plutonium process waste is a candidate for waste minimization by recycling. Process simulation software packages, such as Aspen, are valuable tools to estimate how effective recovery processes can be, however, constants in equations of state for many ionic components are not in their data libraries. One option is to combine single salt solubility`s in the Aspen model for mixed salt system. Single salt solubilities were regressed in Aspen within 0.82 weight percent of literature values. These were combined into a single Aspen model and used in the mixed salt studies. A simulated nitric acid waste containing mixed aluminum, calcium, iron, magnesium and sodium nitrate was tested to determine points of solubility between 25 and 100 C. Only four of the modeled experimental conditions, at 50 C and 75 C, produced a saturated solution. While experimental results indicate that sodium nitrate is the first salt to crystallize out, the Aspen computer model shows that the most insoluble salt, magnesium nitrate, the first salt to crystallize. Possible double salt formation is actually taking place under experimental conditions, which is not captured by the Aspen model.

Orbital Express mission operations planning and resource management using ASPEN

Science.gov (United States)

Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Daniel

2008-04-01

As satellite equipment and mission operations become more costly, the drive to keep working equipment running with less labor-power rises. Demonstrating the feasibility of autonomous satellite servicing was the main goal behind the Orbital Express (OE) mission. Like a tow-truck delivering gas to a car on the road, the "servicing" satellite of OE had to find the "client" from several kilometers away, connect directly to the client, and transfer fluid (or a battery) autonomously, while on earth-orbit. The mission met 100% of its success criteria, and proved that autonomous satellite servicing is now a reality for space operations. Planning the satellite mission operations for OE required the ability to create a plan which could be executed autonomously over variable conditions. As the constraints for execution could change weekly, daily, and even hourly, the tools used create the mission execution plans needed to be flexible and adaptable to many different kinds of changes. At the same time, the hard constraints of the plans needed to be maintained and satisfied. The Automated Scheduling and Planning Environment (ASPEN) tool, developed at the Jet Propulsion Laboratory, was used to create the schedule of events in each daily plan for the two satellites of the OE mission. This paper presents an introduction to the ASPEN tool, an overview of the constraints of the OE domain, the variable conditions that were presented within the mission, and the solution to operations that ASPEN provided. ASPEN has been used in several other domains, including research rovers, Deep Space Network scheduling research, and in flight operations for the NASA's Earth Observing One mission's EO1 satellite. Related work is discussed, as are the future of ASPEN and the future of autonomous satellite servicing.

Evaluation of Whole Tree Growth Increment Derived from Tree-Ring Series for Use in Assessments of Changes in Forest Productivity across Various Spatial Scales

Directory of Open Access Journals (Sweden)

Juha M. Metsaranta

2016-12-01

Full Text Available The inherent predictability of inter-annual variation in forest productivity remains unknown. Available field-based data sources for understanding this variability differ in their spatial resolution, temporal resolution, and typical units of measure. Nearly all other tree and forest characteristics are in practice derived from measurements of diameter at breast height (DBH. Therefore, diameter increment reconstructed annually from tree-ring data can be used to estimate annual growth increments of wood volume, but the accuracy and precision of these estimates requires assessment. Annual growth estimates for n = 170 trees sampled for whole stem analysis from five tree species (jack pine, lodgepole pine, black spruce, white spruce, and trembling aspen in Western Canada were compared against increments derived from breast height measurements only. Inter-annual variability of breast height and whole tree growth increments was highly correlated for most trees. Relative errors varied by species, diameter class, and the equation used to estimate volume (regional vs. national. A simple example of the possible effect of this error when propagated to the stand level is provided.

Age-related patterns of forest complexity and carbon storage in pine and aspen-birch ecosystems of northern Minnesota, USA

International Nuclear Information System (INIS)

Bradford, J.B.; Kastendick, D.N.

2010-01-01

Forest managers are now developing strategies to mitigate increases in atmospheric carbon dioxide (CO 2 ) and help stands to adapt to new climatic conditions. This study characterized the influence of stand age on carbon storage and sequestration in chronosequences of even-aged red pine and aspen-birch stands in northern Minnesota. The aim of the study was to determine the impact of age-related management strategies on carbon storage and forest complexity. The pine chronosequences ranged from 7 to 160 years. Aspen chronosequences ranged from 6 to 133 years. Field measurements of the trees were compiled into 5 carbon pools. Carbon storage variables were averaged within each stand in order to conduct a regression analysis. The study showed that forest complexity was positively related to stand age in all of the measured response variables except species richness. Relationships between compositional complexity and stand age depended on forest type. Total carbon storage also increased with age. Results of the study showed that age plays an important role in overall ecosystem carbon storage. The study can be used to provide insights into the overall costs and benefits of forest management strategies that favour younger or older forests. 45 refs., 2 figs.

Aspen Characteristics - Plumas National Forest, FRRD [ds375

Data.gov (United States)

California Natural Resource Agency — The database represents point locations and associated stand assessment data collected within aspen stands in the Plumas National Forest, Feather River Ranger...

Factors influencing epiphytic lichen communities in aspen-associated forests of the Bear River Range, Idaho and Utah

Science.gov (United States)

Paul C. Rogers

2007-01-01

In western North America, quaking aspen (Populus tremuloides Michx.) is the most common hardwood in montane landscapes. Fire suppression, grazing, wildlife management practices, and climate patterns of the past century are some of the threats to aspen coverage in this region. Researchers are concerned that aspen-dependent species may be losing...

Fibrillation of Aspen by Alkaline Cold Pre-treatment and Vibration Milling

Directory of Open Access Journals (Sweden)

Kärt KÄRNER

2016-09-01

Full Text Available In this article an attempt to fibrillate aspen bleached chemi-thermo mechanical pulp (BCTMP fibre in an environmentally friendly way is reported. The effects of various NaOH, KOH, urea and ethanol aqueous solutions at lowered temperature were tested for pre-treatment. The pre-treatment was followed by vibration milling aiming to peel off outer cell wall layers and to fibrillate S2 layer of the aspen wood fibre. The effects of the treatments were evaluated by scanning electron microscopy (SEM. The results show that it is possible to fibrillate BCTMP aspen fibres by using alkaline aqueous solutions at low temperatures followed by a mechanical treatment. A strong dependence on fibrillation of cellulose on temperature, time and alkali concentration was established.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.7412

Using user models in Matlab® within the Aspen Plus® interface with an Excel® link

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Javier Fontalvo Alzate

2014-05-01

Full Text Available Process intensification and new technologies require tools for process design that can be integrated into well-known simulation software, such as Aspen Plus®. Thus, unit operations that are not included in traditional Aspen Plus software packages can be simulated with Matlab® and integrated within the Aspen Plus interface. In this way, the user can take advantage of all of the tools of Aspen Plus, such as optimization, sensitivity analysis and cost estimation. This paper gives a detailed description of how to implement this integration. The interface between Matlab and Aspen Plus is accomplished by sending the relevant information from Aspen Plus to Excel, which feeds the information to a Matlab routine. Once the Matlab routine processes the information, it is returned to Excel and to Aspen Plus. This paper includes the Excel and Matlab template files so the reader can implement their own simulations. By applying the protocol described here, a hybrid distillation-vapor permeation system has been simulated as an example of the applications that can be implemented. For the hybrid system, the effect of membrane selectivity on membrane area and reboiler duty for the partial dehydration of ethanol is studied. Very high selectivities are not necessarily required for an optimum hybrid distillation and vapor permeation system.

Nest-site selection and nest survival of Lewis's woodpecker in aspen riparian woodlands

Science.gov (United States)

Karen R. Newlon; Victoria A. Saab

2011-01-01

Riparian woodlands of aspen (Populus tremuloides) provide valuable breeding habitat for several cavity-nesting birds. Although anecdotal information for this habitat is available for Lewis's Woodpecker (Melanerpes lewis), no study has previously examined the importance of aspen woodlands to this species' breeding biology. From 2002 to 2004, we monitored 76...

Comparison of tree types of models for the prediction of final academic achievement

Directory of Open Access Journals (Sweden)

Silvana Gasar

2002-12-01

Full Text Available For efficient prevention of inappropriate secondary school choices and by that academic failure, school counselors need a tool for the prediction of individual pupil's final academic achievements. Using data mining techniques on pupils' data base and expert modeling, we developed several models for the prediction of final academic achievement in an individual high school educational program. For data mining, we used statistical analyses, clustering and two machine learning methods: developing classification decision trees and hierarchical decision models. Using an expert system shell DEX, an expert system, based on a hierarchical multi-attribute decision model, was developed manually. All the models were validated and evaluated from the viewpoint of their applicability. The predictive accuracy of DEX models and decision trees was equal and very satisfying, as it reached the predictive accuracy of an experienced counselor. With respect on the efficiency and difficulties in developing models, and relatively rapid changing of our education system, we propose that decision trees are used in further development of predictive models.

Diet preference of Eurasian Beaver (Castor Fiber L., 1758 in the environment of Oderské vrchy and its influence on the tree species composition of river bank stands

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Jan Dvořák

2013-01-01

Full Text Available This paper deals with the dietary behaviour and the tree species preference in the river bank stands in the diet of established population Eurasian Beaver (Castor fiber L., 1758 in the environment of Oderské vrchy; the objective is to assess the suitability of this environment for future development of the Eurasian Beaver and to asses the influence of the beaver’s dietary behaviour on the river bank stands. In the monitored area, the total of 5 tree species with the following preference were recorded: willow (Salix 42.2%, aspen (Populus 28%, dogwood (Comus 15.5%, birch (Betula 7.4% and alder (Alnus 6.9%. The most damaged diameter interval recorded within the all damaged tree species ranges from 2.6 to 6 cm, followed by the interval 6.1–12 cm. Over 61% of the trees felled by the beaver had a bigger diameter. The most sensitive reaction to beaver’s dietary behaviour was shown by aspen (reduction of numbers by 27.6% and by willow (reduction of numbers by 16.6% on the monitored area.

Identifying and Characterizing Important Trembling Aspen Competitors with Juvenile Lodgepole Pine in Three South-Central British Columbia Ecosystems

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Teresa A. Newsome

2012-01-01

Full Text Available Critical height ratios for predicting competition between trembling aspen and lodgepole pine were identified in six juvenile stands in three south-central British Columbia ecosystems. We used a series of regression analyses predicting pine stem diameter from the density of neighbouring aspen in successively shorter relative height classes to identify the aspen-pine height ratio that maximized R2. Critical height ratios varied widely among sites when stands were 8–12 years old but, by age 14–19, had converged at 1.25–1.5. Maximum R2 values at age 14–19 ranged from 13.4% to 69.8%, demonstrating that the importance of aspen competition varied widely across a relatively small geographic range. Logistic regression also indicated that the risk of poor pine vigour in the presence of aspen varied between sites. Generally, the degree of competition, risk to pine vigour, and size of individual aspen contributing to the models declined along a gradient of decreasing ecosystem productivity.

The aspen mortality summit; December 18 and 19, 2006; Salt Lake City, UT

Science.gov (United States)

Dale L. Bartos; Wayne D. Shepperd

2010-01-01

The USDA Forest Service Rocky Mountain Research Station sponsored an aspen summit meeting in Salt Lake City, Utah, on December 18 and19, 2006, to discuss the rapidly increasing mortality of aspen (Populus tremuloides) throughout the western United States. Selected scientists, university faculty, and managers from Federal, State, and non-profit agencies with experience...

76 FR 69279 - Notice of Intent to Prepare an Environmental Impact Statement for the Quaking Aspen Wind Energy...

Science.gov (United States)

2011-11-08

... Intent to Prepare an Environmental Impact Statement for the Quaking Aspen Wind Energy Project, Wyoming... Statement (EIS) for the Quaking Aspen Wind Energy Project (Quaking Aspen). By this notice, BLM is: (1..._Wind_Energy[email protected] ; or Mail: 280 Highway 191 N., Rock Springs, WY 82901. Documents pertinent to...

Chemical studies on oils derived from aspen poplar wood, cellulose, and an isolated aspen poplar lignin

Energy Technology Data Exchange (ETDEWEB)

Eager, R L; Pepper, J M; Roy, J C; Mathews, J F

1983-01-01

An initial study has been made of the chemical nature of the oil phase resulting from the conversion of aspen poplar wood, cellulose, and an isolated lignin from the aspen poplar as a result of their interactions with water and carbon monoxide in the presence of sodium carbonate at 360 degrees C. Gas chromatographic analysis of the sodium hydroxide soluble fractions from each substrate revealed similar spectra of alkyl-substituted phenols. The relative abundance of identified low molecular weight phenolic compounds decreased from lignin to wood to cellulose. This was in agreement with the known phenolic nature of lignin. As well, it confirmed the synthesis during reaction of such compounds from a carbohydrate substrate. Gas chromatographic analysis of the whole oils also revealed the presence in each case of several alkyl-substituted cyclopentanones whose relative abundance decreased from cellulose to wood to lignin. Silica gel column separation of the oils, after a charcoal treatment, followed by capillary gas chromatographic - mass spectrometric analyses of the resulting fraction indicated the presence of other higher molecular weight phenols, napthols, cycloalkanols, and polycyclic and long chain alkanes and alkenes.

Evaluation to the aspen for the air pollution monitoring

International Nuclear Information System (INIS)

De La Rosa, D.; Lima, L.; Santana, J.L.; Olivares, S.; Martin, R.; Garcia, M.

2003-01-01

Aspen is not often used in bio monitoring programs, but when it is, several interacting and confounding variables have to be considered. Biomass of leaves, and height changes are not easy linked with air pollution, whereas dry weight and leaf abscission are. Visible injury diagnosis and crown thinning are useful records for bio monitoring programs to consider, but skill and understanding of air pollution effects versus seasonal effects are very important. Understanding of actual air pollution symptoms and elemental ratios are especially important. Clonal response and heritability is discuses below, and has to be considered in any bio monitoring program. Above all, integration of aspen response with other key variables is key

Experimental Study of Impregnation Birch and Aspen Samples

Directory of Open Access Journals (Sweden)

Igor Vladislavovich Grigorev

2014-10-01

Full Text Available An experimental study of wood impregnation was implemented by applying centrifugal methods. The impregnants were a 10% aqueous solution of potassium chloride and a 2% aqueous solution of borax. Birch (Betula pendula and aspen (Populus tremula wood samples in different moisture content were tested. The impregnation time in the centrifugal device were 30 seconds repeated 21 times, and the samples were measured after every 30 seconds. The experimental results were fitted to a nonlinear filtration law, which indicated that the centrifugal wood impregnation was dependent on wood species, wood moisture, rotational speed, and radius. Determination of rotational speed and centrifuge radius for impregnating aspen and birch at varying lengths and humidity under conditions of the nonlinear impregnant filtration law can be done using the example charts that were developed and presented in this study.

Understanding the role of the cytoskeleton in wood formation in angiosperm trees: hybrid aspen (Populus tremula x P. tremuloides) as the model species.

Science.gov (United States)

Chaffey, Nigel; Barlow, Peter; Sundberg, Björn

2002-03-01

The involvement of microfilaments and microtubules in the development of the radial and axial components of secondary xylem (wood) in hybrid aspen (Populus tremula L. x P. tremuloides Michx.) was studied by indirect immunofluorescent localization techniques. In addition to cambial cells, the differentiated cell types considered were early- and late-wood vessel elements, axial parenchyma, normal-wood fibers and gelatinous fibers, and contact and isolation ray cells. Microfilaments were rare in ray cambial cells, but were abundant and axially arranged in their derivatives once cell elongation had begun, and persisted in that orientation in mature ray cells. Microfilaments were axially arranged in fusiform cambial cells and persisted in that orientation in all xylem derivatives of those cells. Microtubules were randomly oriented in ray and fusiform cells of the cambial zone. Dense arrays of parallel-aligned microtubules were oriented near axially in the developing gelatinous fibers, but at a wide range of angles in normal-wood fibers. Ellipses of microfilaments were associated with pit development in fiber cells and isolation ray cells. Rings of co-localized microtubules and microfilaments were associated with developing inter-vessel bordered pits and vessel-contact ray cell contact pits, and, in the case of bordered pits, these rings decreased in diameter as the over-arching pit border increased in size. Although only microtubules were seen at the periphery of the perforation plate of vessel elements, a prominent meshwork of microfilaments overlaid the perforation plate itself. A consensus view of the roles of the cytoskeleton during wood formation in angiosperm trees is presented.

Aspen HYSYS process simulation and Aspen ICARUS cost estimation of CO2 removal plant

OpenAIRE

Vozniuk, Ievgeniia Oleksandrivna

2010-01-01

An Aspen HYSYS model of CO2 removal was developed and modified with a split-stream configuration in order to reduce energy consumption in the reboiler. The model has been calculated with variation of parameters to optimize the process and find an optimum solution. For the selected base cases the heat exchanger minimum temperature difference was specified to 10K and the removal efficiency was 85%. The reboiler duty of 3.8 MJ/kg CO2 removed for the standard process without split-stream was ...

Modeling the Removal of Xenon from Lithium Hydrate with Aspen HYSYS

Science.gov (United States)

Efthimion, Phillip; Gentile, Charles

2011-10-01

The Laser Inertial Fusion Engine (LIFE) project mission is to provide a long-term, carbon-free source of sustainable energy, in the form of electricity. A conceptual xenon removal system has been modeled with the aid of Aspen HYSYS, a chemical process simulator. Aspen HYSYS provides excellent capability to model chemical flow processes, which generates outputs which includes specific variables such as temperature, pressure, and molar flow. The system is designed to strip out hydrogen isotopes deuterium and tritium. The base design bubbles plasma exhaust laden with x filled with liquid helium. The system separates the xenon from the hydrogen, deuterium, and tritium with a lithium hydrate and a lithium bubbler. After the removal of the hydrogen and its isotopes, the xenon is then purified by way of the process of cryogenic distillation. The pure hydrogen, deuterium, and tritium are then sent to the isotope separation system (ISS). The removal of xenon is an integral part of the laser inertial fusion engine and Aspen HYSYS is an excellent tool to calculate how to create pure xenon.

Effects of genotype, elevated CO2 and elevated O3 on aspen phytochemistry and aspen leaf beetle Chrysomela crotchi performance

Science.gov (United States)

Leanne M. Vigue; Richard L. Lindroth

2010-01-01

Trembling aspen Populus tremuloides Michaux is an important forest species in the Great Lakes region and displays tremendous genetic variation in foliar chemistry. Elevated carbon dioxide (CO2) and ozone (O3) may also influence phytochemistry and thereby alter the performance of insect herbivores such as...

Dying piece by piece: carbohydrate dynamics in aspen (Populus tremuloides) seedlings under severe carbon stress.

Science.gov (United States)

Wiley, Erin; Hoch, Günter; Landhäusser, Simon M

2017-11-02

Carbon starvation as a mechanism of tree mortality is poorly understood. We exposed seedlings of aspen (Populus tremuloides) to complete darkness at 20 or 28 °C to identify minimum non-structural carbohydrate (NSC) concentrations at which trees die and to see if these levels vary between organs or with environmental conditions. We also first grew seedlings under different shade levels to determine if size affects survival time under darkness due to changes in initial NSC concentration and pool size and/or respiration rates. Darkness treatments caused a gradual dieback of tissues. Even after half the stem had died, substantial starch reserves were still present in the roots (1.3-3% dry weight), indicating limitations to carbohydrate remobilization and/or transport during starvation in the absence of water stress. Survival time decreased with increased temperature and with increasing initial shade level, which was associated with smaller biomass, higher respiration rates, and initially smaller NSC pool size. Dead tissues generally contained no starch, but sugar concentrations were substantially above zero and differed between organs (~2% in stems up to ~7.5% in leaves) and, at times, between temperature treatments and initial, pre-darkness shade treatments. Minimum root NSC concentrations were difficult to determine because dead roots quickly began to decompose, but we identify 5-6% sugar as a potential threshold for living roots. This variability may complicate efforts to identify critical NSC thresholds below which trees starve. © Society for Experimental Biology 2017.

Modeling of existing cooling towers in ASPEN PLUS using an equilibrium stage method

International Nuclear Information System (INIS)

Queiroz, João A.; Rodrigues, Vitor M.S.; Matos, Henrique A.; Martins, F.G.

2012-01-01

Highlights: ► Simulation of cooling tower performance under different operating conditions. ► Cooling tower performance is simulated using ASPEN PLUS. ► Levenberg–Marquardt method used to adjust model parameters. ► Air and water outlet temperatures are in good accordance with experimental data. - Abstract: Simulation of cooling tower performance considering operating conditions away from design is typically based on the geometrical parameters provided by the cooling tower vendor, which are often unavailable or outdated. In this paper a different approach for cooling tower modeling based on equilibrium stages and Murphree efficiencies to describe heat and mass transfer is presented. This approach is validated with published data and with data collected from an industrial application. Cooling tower performance is simulated using ASPEN PLUS. Murphree stage efficiency values for the process simulator model were optimized by minimizing the squared difference between the experimental and calculated data using the Levenberg–Marquardt method. The minimization algorithm was implemented in Microsoft Excel with Visual Basic for Applications, integrated with the process simulator (ASPEN PLUS) using Aspen Simulation Workbook. The simulated cooling tower air and water outlet temperatures are in good accordance with experimental data when applying only the outlet water temperature to calibrate the model. The methodology is accurate for simulating cooling towers at different operational conditions.

2012 Aspen Winter Conferences on High Energy and Astrophysics

Energy Technology Data Exchange (ETDEWEB)

Campbell, John [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Olivier, Dore [California Inst. of Technology (CalTech), Pasadena, CA (United States); Fox, Patrick [Aspen Center for Physics, CO (United States); Furic, Ivan [Univ. of Florida, Gainesville, FL (United States); Halkiadakis, Eva [Rutgers Univ., Piscataway, NJ (United States); Schmidt, Fabian [California Inst. of Technology (CalTech), Pasadena, CA (United States); Senatore, Leonardo [Stanford Univ., CA (United States); Smith, Kendrick M. [Princeton Univ., NJ (United States); Whiteson, Daniel [Univ. of California, Irvine, CA (United States)

2012-05-01

Aspen Center for Physics Project Summary DE-SC0007313 Budget Period: 1/1/2012 to 12/31/2012 The Hunt for New Particles, from the Alps to the Plains to the Rockies The 2012 Aspen Winter Conference on Particle Physics was held at the Aspen Center for Physics from February 11 to February 17, 2012. Sixty-seven participants from nine countries, and several universities and national labs attended the workshop titled, The Hunt for New Particles, from the Alps to the Plains to the Rockies. There were 53 formal talks, and a considerable number of informal discussions held during the week. The weeks events included a public lecture-Hunting the Dark Universe given by Neal Weiner from New York University) and attended by 237 members of the public, and a physics cafe geared for high schoolers that is a discussion with physicists conducted by Spencer Chang (University of Oregon), Matthew Reece (Harvard University) and Julia Shelton (Yale University) and attended by 67 locals and visitors. While there were no published proceedings, some of the talks are posted online and can be Googled. The workshop was organized by John Campbell (Fermilab), Patrick Fox (Fermilab), Ivan Furic (University of Florida), Eva Halkiadakis (Rutgers University) and Daniel Whiteson (University of California Irvine). Additional information is available at http://indico.cern.ch/conferenceDisplay.py?confId=143360. Inflationary Theory and its Confrontation with Data in the Planck Era The 2012 Aspen Winter Conference on Astroparticle physics held at the Aspen Center for Physics was Inflationary Theory and its Confrontation with Data in the Planck Era. It was held from January 30 to February 4, 2012. The 62 participants came from 7 countries and attended 43 talks over five days. Late mornings through the afternoon are reserved for informal discussions. In feedback received from participants, it is often these unplanned chats that produce the most excitement due to working through problems with fellow physicists

Aspen Ecology in Rocky Mountain National Park: Age Distribution, Genetics, and the Effects of Elk Herbivory

Energy Technology Data Exchange (ETDEWEB)

Tuskan, Gerald A [ORNL; Yin, Tongming [ORNL

2008-10-01

Lack of aspen (Populus tremuloides) recruitment and canopy replacement of aspen stands that grow on the edges of grasslands on the low-elevation elk (Cervus elaphus) winter range of Rocky Mountain National Park (RMNP) in Colorado has been a cause of concern for more than 70 years (Packard, 1942; Olmsted, 1979; Stevens, 1980; Hess, 1993; R.J. Monello, T.L. Johnson, and R.G. Wright, Rocky Mountain National Park, 2006, written commun.). These aspen stands are a significant resource since they are located close to the park's road system and thus are highly visible to park visitors. Aspen communities are integral to the ecological structure of montane and subalpine landscapes because they contain high native species richness of plants, birds, and butterflies (Chong and others, 2001; Simonson and others, 2001; Chong and Stohlgren, 2007). These low-elevation, winter range stands also represent a unique component of the park's plant community diversity since most (more than 95 percent) of the park's aspen stands grow in coniferous forest, often on sheltered slopes and at higher elevations, while these winter range stands are situated on the low-elevation ecotone between the winter range grasslands and some of the park's drier coniferous forests.

Increased saccharification yields from aspen biomass upon treatment with enzymatically generated peracetic acid.

Science.gov (United States)

Duncan, Shona; Jing, Qing; Katona, Adrian; Kazlauskas, Romas J; Schilling, Jonathan; Tschirner, Ulrike; Aldajani, Waleed Wafa

2010-03-01

The recalcitrance of lignocellulosic biomass to enzymatic release of sugars (saccharification) currently limits its use as feedstock for biofuels. Enzymatic hydrolysis of untreated aspen wood releases only 21.8% of the available sugars due primarily to the lignin barrier. Nature uses oxidative enzymes to selectively degrade lignin in lignocellulosic biomass, but thus far, natural enzymes have been too slow for industrial use. In this study, oxidative pretreatment with commercial peracetic acid (470 mM) removed 40% of the lignin (from 19.9 to 12.0 wt.% lignin) from aspen and enhanced the sugar yields in subsequent enzymatic hydrolysis to about 90%. Increasing the amount of lignin removed correlated with increasing yields of sugar release. Unfortunately, peracetic acid is expensive, and concentrated forms can be hazardous. To reduce costs and hazards associated with using commercial peracetic acid, we used a hydrolase to catalyze the perhydrolysis of ethyl acetate generating 60-70 mM peracetic acid in situ as a pretreatment to remove lignin from aspen wood. A single pretreatment was insufficient, but multiple cycles (up to eight) removed up to 61.7% of the lignin enabling release of >90% of the sugars during saccharification. This value corresponds to a predicted 581 g of fermentable sugars from 1 kg of aspen wood. Improvements in the enzyme stability are needed before the enzymatically generated peracetic acid is a commercially viable alternative.

The 2013 Aspen Prize for Community College Excellence

Science.gov (United States)

Perlstein, Linda

2013-01-01

For millions of Americans, community colleges provide an essential pathway to well-paying jobs and continuing higher education. The Aspen Prize for Community College Excellence honors those institutions that strive for and achieve exceptional levels of success for all students, while they are in college and after they graduate. Community colleges…

Analysis of Cryogenic Cycle with Process Modeling Tool: Aspen HYSYS

Science.gov (United States)

Joshi, D. M.; Patel, H. K.

2015-10-01

Cryogenic engineering deals with the development and improvement of low temperature techniques, processes and equipment. A process simulator such as Aspen HYSYS, for the design, analysis, and optimization of process plants, has features that accommodate the special requirements and therefore can be used to simulate most cryogenic liquefaction and refrigeration processes. Liquefaction is the process of cooling or refrigerating a gas to a temperature below its critical temperature so that liquid can be formed at some suitable pressure which is below the critical pressure. Cryogenic processes require special attention in terms of the integration of various components like heat exchangers, Joule-Thompson Valve, Turbo expander and Compressor. Here, Aspen HYSYS, a process modeling tool, is used to understand the behavior of the complete plant. This paper presents the analysis of an air liquefaction plant based on the Linde cryogenic cycle, performed using the Aspen HYSYS process modeling tool. It covers the technique used to find the optimum values for getting the maximum liquefaction of the plant considering different constraints of other parameters. The analysis result so obtained gives clear idea in deciding various parameter values before implementation of the actual plant in the field. It also gives an idea about the productivity and profitability of the given configuration plant which leads to the design of an efficient productive plant.

Analysis of Cryogenic Cycle with Process Modeling Tool: Aspen HYSYS

International Nuclear Information System (INIS)

Joshi, D.M.; Patel, H.K.

2015-01-01

Cryogenic engineering deals with the development and improvement of low temperature techniques, processes and equipment. A process simulator such as Aspen HYSYS, for the design, analysis, and optimization of process plants, has features that accommodate the special requirements and therefore can be used to simulate most cryogenic liquefaction and refrigeration processes. Liquefaction is the process of cooling or refrigerating a gas to a temperature below its critical temperature so that liquid can be formed at some suitable pressure which is below the critical pressure. Cryogenic processes require special attention in terms of the integration of various components like heat exchangers, Joule-Thompson Valve, Turbo expander and Compressor. Here, Aspen HYSYS, a process modeling tool, is used to understand the behavior of the complete plant. This paper presents the analysis of an air liquefaction plant based on the Linde cryogenic cycle, performed using the Aspen HYSYS process modeling tool. It covers the technique used to find the optimum values for getting the maximum liquefaction of the plant considering different constraints of other parameters. The analysis result so obtained gives clear idea in deciding various parameter values before implementation of the actual plant in the field. It also gives an idea about the productivity and profitability of the given configuration plant which leads to the design of an efficient productive plant

Summary and abstracts from Sudden Aspen Decline (SAD) Meeting; Fort Collins, Colorado, February 12-13, 2008

Science.gov (United States)

Paul C. Rogers

2008-01-01

In recent years the aspen research and management community has witnessed increasing accounts of unexplained aspen die-offs across the Rocky Mountain region. In response, two meetings were held to address the issue; this paper summarizes the most recent gathering, a symposium held in Fort Collins at the USDA Forest Service, Rocky Mountain Research Station, on February...

Bio energy production in birch and hybrid aspen after addition of residue based fertilizers - establishment of fertilization trials; Bioenergiproduktion hos bjoerk och hybridasp vid tillfoersel av restproduktbaserade goedselmedel - etablering av goedslingsfoersoek

Energy Technology Data Exchange (ETDEWEB)

Thelin, Gunnar (EkoBalans Fenix AB, Malmoe (Sweden))

2009-03-15

Sewage sludge and wood ashes could be used as fertilizers in order to increase forest tree production. In southern Sweden forest growth normally increases with approximately 10 % after ash recycling due to increased N and/or P availability. P is added with the ashes and the pH-increasing effect of the wood ash can lead to increased N net mineralization. Other positive effects of wood ash recycling are improved nutrient sustainability and less acid run-off water. Possible negative effects are heavy metal accumulation, if the content of one or more heavy metals of the recycled ash exceeds the heavy metal content of the harvested biomass, and nitrate leaching if the vegetation cannot take up nitrified N. It is important to evaluate the sustainability of fertilization systems based on residues such as sludge and wood ash. Wood ash does not contain N and the P concentration often is too low for the ashes to function as an NP fertilizer. Thus N and sometimes P must be added. Sludge is an interesting alternative. The main purpose of the project is to study sustainable production of forest bio energy in intensively cultivated birch and hybrid aspen stands. Another purpose is to establish experiments that can be used for long term studies and as demonstration objects. In the first few years the goal is to study the short term effects of residue based fertilization compared to conventional NPK fertilization on tree nutrient uptake, nutrient leaching, sustainability and economy. In the long term the goal is to design appropriate fertilization strategies in a residue based fertilization system for the intensive cultivation of birch and hybrid aspen without negative side effects such as large scale nutrient leaching. Four field experiments were established in 2008 and one additional experiment in hybrid aspen will be established in the spring of 2009. Elevated bud N and P concentrations after fertilization with both Ashes+N and NPK means good possibilities for future growth

Ectopic expression of a horseradish peroxidase enhances growth rate and increases oxidative stress resistance in hybrid aspen.

Science.gov (United States)

Kawaoka, Akiyoshi; Matsunaga, Etsuko; Endo, Saori; Kondo, Shinkichi; Yoshida, Kazuya; Shinmyo, Atsuhiko; Ebinuma, Hiroyasu

2003-07-01

We previously demonstrated that overexpression of the horseradish (Armoracia rusticana) peroxidase prxC1a gene stimulated the growth rate of tobacco (Nicotiana tabacum) plants. Here, the cauliflower mosaic virus 35S::prxC1a construct was introduced into hybrid aspen (Populus sieboldii x Populus grandidentata). The growth rate of these transformed hybrid aspen plants was substantially increased under greenhouse conditions. The average stem length of transformed plants was 25% greater than that of control plants. There was no other obvious phenotypic difference between the transformed and control plants. Fast-growing transformed hybrid aspen showed high levels of expression of prxC1a and had elevated peroxidase activities toward guaiacol and ascorbate. However, there was no increase of the endogenous class I ascorbate peroxidase activities in the transformed plants by separate assay and activity staining of native polyacrylamide gel electrophoresis. Furthermore, calli derived from the transformed hybrid aspen grew faster than those from control plants and were resistant to the oxidative stress imposed by hydrogen peroxide. Therefore, enhanced peroxidase activity affects plant growth rate and oxidative stress resistance.

Bioenergy harvest impacts to biodiversity and resilience vary across aspen-dominated forest ecosystems in the Lake States region, USA

Science.gov (United States)

Miranda T. Curzon; Anthony W. D' Amato; Brian J. Palik; Kris Verheyen

2016-01-01

Questions: Does the increase in disturbance associated with removing harvest residues negatively impact biodiversity and resilience in aspen-dominated forest ecosystems? How do responses of functional diversity measures relate to community recovery and standing biomass? Location: Aspen (Populus tremuloides, Michx.) mixedwood forests in Minnesota...

Defining Excellence: Lessons from the 2013 Aspen Prize Finalists

Science.gov (United States)

Aspen Institute, 2013

2013-01-01

In many respects, one couldn't find a group of 10 schools more diverse than the finalists for the 2013 Aspen Prize for Community College Excellence. One community college serves 1,500 students, another 56,000. There are institutions devoted primarily--even solely--to technical degrees, and ones devoted mainly to preparing students for further…

Regional Models of Diameter as a Function of Individual Tree Attributes, Climate and Site Characteristics for Six Major Tree Species in Alberta, Canada

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Dan A. MacIsaac

2011-09-01

Full Text Available We investigated the relationship of stem diameter to tree, site and stand characteristics for six major tree species (trembling aspen, white birch, balsam fir, lodgepole pine, black spruce, and white spruce in Alberta (Canada with data from Alberta Sustainable Resource Development Permanent Sample Plots. Using non-linear mixed effects modeling techniques, we developed models to estimate diameter at breast height using height, crown and stand attributes. Mixed effects models (with plot as subject using height, crown area, and basal area of the larger trees explained on average 95% of the variation in diameter at breast height across the six species with a root mean square error of 2.0 cm (13.4% of mean diameter. Fixed effects models (without plot as subject including the Natural Sub-Region (NSR information explained on average 90% of the variation in diameter at breast height across the six species with a root mean square error equal to 2.8 cm (17.9% of mean diameter. Selected climate variables provided similar results to models with NSR information. The inclusion of nutrient regime and moisture regime did not significantly improve the predictive ability of these models.

Effect of Tree Species on Enzyme Secretion by the Shiitake Medicinal Mushroom, Lentinus edodes (Agaricomycetes).

Science.gov (United States)

Plotnikov, Evgeny V; Glukhova, Lubov B; Sokolyanskaya, Ludmila O; Karnachuk, Olga V; Solioz, Marc

2016-01-01

We compared cold and hot wood extracts of 3 endemic Siberian trees-namely, Prunus padus (bird cherry), Populus tremula (aspen), and Betula sp. (birch)-on biomass production and laccase and peroxidase secretion in submerged cultures by the medicinal mushroom Lentinus edodes. Of the conditions tested, only hot Prunus extracts stimulated biomass production, whereas all extracts stimulated laccase and peroxidase secretion, albeit to different extents. A large, differential stimulation of manganese peroxidase was observed by hot Prunus extracts. The results highlight important differences between tree species in the stimulation of biomass and enzyme production by L. edodes and point to potentially interesting stimulatory factors present in hot Prunus extracts. These findings are of relevance in the use of L. edodes for medicinal or biotechnological applications.

Genetic, morphological, and spectral characterization of relictual Niobrara River hybrid aspens (Populus × smithii).

Science.gov (United States)

Deacon, Nicholas John; Grossman, Jake Joseph; Schweiger, Anna Katharina; Armour, Isabella; Cavender-Bares, Jeannine

2017-12-01

Aspen groves along the Niobrara River in Nebraska have long been a biogeographic curiosity due to morphological differences from nearby remnant Populus tremuloides populations. Pleistocene hybridization between P. tremuloides and P. grandidentata has been proposed, but the nearest P. grandidentata populations are currently several hundred kilometers east. We tested the hybrid-origin hypothesis using genetic data and characterized putative hybrids phenotypically. We compared nuclear microsatellite loci and chloroplast sequences of Niobrara River aspens to their putative parental species. Parental species and putative hybrids were also grown in a common garden for phenotypic comparison. On the common garden plants, we measured leaf morphological traits and leaf-level spectral reflectance profiles, from which chemical traits were derived. The genetic composition of the three unique Niobrara aspen genotypes is consistent with the hybridization hypothesis and with maternal chloroplast inheritance from P. grandidentata . Leaf margin dentition and abaxial pubescence differentiated taxa, with the hybrids showing intermediate values. Spectral profiles allowed statistical separation of taxa in short-wave infrared wavelengths, with hybrids showing intermediate values, indicating that traits associated with internal structure of leaves and water absorption may vary among taxa. However, reflectance values in the visible region did not differentiate taxa, indicating that traits related to pigments are not differentiated. Both genetic and phenotypic results support the hypothesis of a hybrid origin for these genetically unique aspens. However, low genetic diversity and ongoing ecological and climatic threats to the hybrid taxon present a challenge for conservation of these relictual boreal communities. © 2017 Botanical Society of America.

Different growth strategies determine the carbon gain and productivity of aspen collectives to be used in short-rotation plantations

International Nuclear Information System (INIS)

Müller, Annika; Horna, Viviana; Zhang, Chunxia; Leuschner, Christoph

2012-01-01

Populus tremula is a favoured tree species in short-rotation forestry with a recognised large intraspecific variation in productivity. We compared the growth potential of 1-yr-old saplings of four Central European aspen collectives with different climate adaptation on a low-fertility site and searched for growth-determining physiological and morphological traits and their dependence on genetic constitution. Among the 35 investigated traits were photosynthetic capacity and mean assimilation rate, quantum yield and carboxylation efficiency, leaf water potential, leaf phaenology and the ratio of leaves lost to leaves produced (LP ratio), leaf size and total leaf area, axes length growth and canopy carbon gain as an estimate of productivity. The collectives differed by more than 30% in cumulative carbon gain with a large genotype effect, while mean assimilation rate and most photosynthetic and water status traits showed a relatively small intraspecific variation with no significant influence on the variation in C gain. The timing of the beginning of net leaf loss (leaf abscission > leaf production) in August differed between the four collectives and resulted in different maximum leaf areas and LP ratios, which were identified as key factors controlling C gain. Mean assimilation rate, though not related to cumulative C gain, was positively correlated with the light, CO 2 and water use efficiencies of photosynthesis. We conclude that genotype selection for high-yielding aspen in short-rotation forestry at low-fertility sites should focus on the parameters leaf phaenology, LP ratio at the end of the growing season, and the resulting total leaf area as key traits.

Tree Regeneration Spatial Patterns in Ponderosa Pine Forests Following Stand-Replacing Fire: Influence of Topography and Neighbors

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Justin P. Ziegler

2017-10-01

Full Text Available Shifting fire regimes alter forest structure assembly in ponderosa pine forests and may produce structural heterogeneity following stand-replacing fire due, in part, to fine-scale variability in growing environments. We mapped tree regeneration in eighteen plots 11 to 15 years after stand-replacing fire in Colorado and South Dakota, USA. We used point pattern analyses to examine the spatial pattern of tree locations and heights as well as the influence of tree interactions and topography on tree patterns. In these sparse, early-seral forests, we found that all species were spatially aggregated, partly attributable to the influence of (1 aspect and slope on conifers; (2 topographic position on quaking aspen; and (3 interspecific attraction between ponderosa pine and other species. Specifically, tree interactions were related to finer-scale patterns whereas topographic effects influenced coarse-scale patterns. Spatial structures of heights revealed conspecific size hierarchies with taller trees in denser neighborhoods. Topography and heterospecific tree interactions had nominal effect on tree height spatial structure. Our results demonstrate how stand-replacing fires create heterogeneous forest structures and suggest that scale-dependent, and often facilitatory, rather than competitive, processes act on regenerating trees. These early-seral processes will establish potential pathways of stand development, affecting future forest dynamics and management options.

Slow lifelong growth predisposes Populus tremuloides to tree mortality

Science.gov (United States)

Kathryn B. Ireland; Margaret M. Moore; Peter Z. Fule; Thomas J. Zegler; Robert E. Keane

2014-01-01

Widespread dieback of aspen forests, sometimes called sudden aspen decline, has been observed throughout much of western North America, with the highest mortality rates in the southwestern United States. Recent aspen mortality has been linked to drought stress and elevated temperatures characteristic of conditions expected under climate change, but the role of...

Effect of Auxins and Associated Metabolic Changes on Cuttings of Hybrid Aspen

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Shao Peng Yan

2017-04-01

Full Text Available In the present study, an attempt was made to induce rooting from single-node cuttings of hybrid aspen (Populus tremula L. × P. tremuloides Michx. with different concentrations of Indole-3-acetic acid (IAA, Indole-3-Butytric acid (IBA and 1-Naphthylacetic acid (NAA. Among the three auxins used, 0.54 mM NAA showed more effective induction on rooting as compared to IAA and IBA at the whole level. Thereafter, 0.54 mM NAA was used further for the anatomical and biochemical investigation. The results showed that it took 12 days from the differentiation of primordium to the appearance of young adventitious roots under NAA application. It was found that endogenous IAA, Zeatin riboside (ZR and Gibberellic Acid (GA3 levels increased, but Abscisic acid (ABA decreased in cuttings with NAA treatment. In contrast to the endogenous IAA level, NAA resulted in a decrease in IAA-oxidase (IAAO activity. Similarly, the decreased peroxidase (POD activity, consistent with down-regulation of expressed levels of POD1 and POD2, was observed in NAA-treated cuttings. Moreover, NAA resulted in a higher activity in polyphenol oxidase (PPO compared with control cuttings. Collectively, the study highlighted that 0.54 mM NAA is efficient on rooting in hybrid aspen, and its effect on metabolic changes during rooting was discussed, which can provide valuable information for propagating hybrid aspen.

Earthworms, arthropods and plant litter decomposition in aspen (Populus tremuloides) and lodgepole pine(Pinus contorta) forests in Colorado, USA

Science.gov (United States)

Grizelle Gonzalez; Timothy R. Seastedt; Zugeily Donato

2003-01-01

We compared the abundance and community composition of earthworms, soil macroarthropods, and litter microarthropods to test faunal effects on plant litter decomposition rates in two forests in the subalpine in Colorado, USA. Litterbags containing recently senesced litter of Populus tremuloides (aspen) and Pinus contorta (lodgepole pine) were placed in aspen and pine...

Historical patterns in lichen communities of montane quaking aspen forests

Science.gov (United States)

Paul C. Rogers; Dale L. Bartos; Ronald J. Ryel

2011-01-01

Climate shifts and resource exploitation in Rocky Mountain forests have caused profound changes in quaking aspen (Populus tremuloides Michx.) structure and function since Euro-American settlement. It therefore seems likely that commensurate shifts in dependent epiphytes would follow major ecological transitions. In the current study, we merge several lines of inquiry...

Establishment of Alleycropped Hybrid Aspen “Crandon” in Central Iowa, USA: Effects of Topographic Position and Fertilizer Rate on Aboveground Biomass Production and Allocation

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Richard B. Hall

2013-07-01

Full Text Available Hybrid poplars have demonstrated high productivity as short rotation woody crops (SRWC in the Midwest USA, and the hybrid aspen “Crandon” (Populus alba L. × P. grandidenta Michx. has exhibited particularly promising yields on marginal lands. However, a key obstacle for wider deployment is the lack of economic returns early in the rotation. Alleycropping has the potential to address this issue, especially when paired with crops such as winter triticale which complete their growth cycle early in the summer and therefore are expected to exert minimal competition on establishing trees. In addition, well-placed fertilizer in low rates at planting has the potential to improve tree establishment and shorten the rotation, which is also economically desirable. To test the potential productivity of “Crandon” alleycropped with winter triticale, plots were established on five topographic positions with four different rates of fertilizer placed in the planting hole. Trees were then harvested from the plots after each of the first three growing seasons. Fertilization resulted in significant increases in branch, stem, and total aboveground biomass across all years, whereas the effects of topographic position varied by year. Allocation between branches and stems was found to be primarily a function of total aboveground biomass.

Elevated CO2 response of photosynthesis depends on ozone concentration in aspen

Science.gov (United States)

Asko Noormets; Olevi Kull; Anu Sober; Mark E. Kubiske; David F. Karnosky

2010-01-01

The effect of elevated CO2 and O3 on apparent quantum yield (ø), maximum photosynthesis (Pmax), carboxylation efficiency (Vcmax) and electron transport capacity (Jmax) at different canopy locations was studied in two aspen (Populus...

Development and validation of the activity significance personal evaluation (ASPEn) scale.

Science.gov (United States)

Mallinson, Trudy; Schepens Niemiec, Stacey L; Carlson, Mike; Leland, Natalie; Vigen, Cheryl; Blanchard, Jeanine; Clark, Florence

2014-12-01

Engagement in desired occupations can promote health and wellbeing in older adults. Assessments of engagement often measure frequency, amount or importance of specific activities. This study aimed to develop a scale to measure older adults' evaluation of the extent to which their everyday activities are contributing to their health and wellness. Eighteen items, each scored with a seven-point rating scale, were initially developed by content experts, covering perceptions of how daily activities contribute to physical and mental health, as well as satisfaction and activity participation in the last six months. Rasch analysis methods were used to refine the scale using the pencil and paper responses of 460 community-living older adults. Initial Rasch analysis indicated three unlabelled rating scale categories were seldom used, reducing measurement precision. Five items were conceptually different by misfit statistics and principal component analysis. Subsequently, those items were removed and the number of rating scale steps reduced to 4. The remaining 13-item, 4-step scale, termed the Activity Significance Personal Evaluation (ASPEn), formed a unidimensional hierarchy with good fit statistics and targeting. Person separation reliability (2.7) and internal consistency (.91) indicated the tool is appropriate for individual person measurement. Relative validity indicated equivalence between Rasch measures and total raw scores. ASPEn is a brief, easily administered assessment of older adults' perception of the contribution of everyday activities to personal health and wellness. ASPEn may facilitate occupational therapy practice by enabling clinicians to assess change in meaning of an older adult's activity over time. © 2014 Occupational Therapy Australia.

Physical property parameter set for modeling ICPP aqueous wastes with ASPEN electrolyte NRTL model

International Nuclear Information System (INIS)

Schindler, R.E.

1996-09-01

The aqueous waste evaporators at the Idaho Chemical Processing Plant (ICPP) are being modeled using ASPEN software. The ASPEN software calculates chemical and vapor-liquid equilibria with activity coefficients calculated using the electrolyte Non-Random Two Liquid (NRTL) model for local excess Gibbs free energies of interactions between ions and molecules in solution. The use of the electrolyte NRTL model requires the determination of empirical parameters for the excess Gibbs free energies of the interactions between species in solution. This report covers the development of a set parameters, from literature data, for the use of the electrolyte NRTL model with the major solutes in the ICPP aqueous wastes

Analyzing tree cores to detect petroleum hydrocarbon-contaminated groundwater at a former landfill site in the community of Happy Valley-Goose Bay, eastern Canadian subarctic

DEFF Research Database (Denmark)

Fonkwe, Merline L D; Trapp, Stefan

2016-01-01

-gas chromatography-mass spectrometry. BTEX compounds were detected in tree cores, corroborating known groundwater contamination. A zone of anomalously high concentrations of total BTEX constituents was identified and recommended for monitoring by groundwater wells. Tree cores collected outside the landfill site......This research examines the feasibility of analyzing tree cores to detect benzene, toluene, ethylbenzene, and m, p, o-xylene (BTEX) compounds and methyl tertiary-butyl ether (MTBE) in groundwater in eastern Canada subarctic environments, using a former landfill site in the remote community of Happy...... Valley-Goose Bay, Labrador. Petroleum hydrocarbon contamination at the landfill site is the result of environmentally unsound pre-1990s disposal of households and industrial solid wastes. Tree cores were taken from trembling aspen, black spruce, and white birch and analyzed by headspace...

A study of polymerization of aspen (Populus) wood lipophilic extractives by SEC and Py-GC/MS

CSIR Research Space (South Africa)

Sithole, Bruce

2013-03-01

Full Text Available ) Orig inal manuscript received 13 June 2012, revision accepted 31 October 2012 Vol 66 No 1 January - March 2013 1 PEER REVIEWED A study of polymerization of aspen (Populus) wood lipophilic extractives by SEC and Py-GC/MS BRUCE SITHOLE1*, LUC... of polymerized wood resin that will be difficult to remove if present in pulp and paper products. On the other hand, these problems may be minor compared to using unseasoned wood. KEYWORDS: Aspen, extractives, polymerization, size exclusion chromatography, Py...

Response Surface Methodology and Aspen Plus Integration for the Simulation of the Catalytic Steam Reforming of Ethanol

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Bernay Cifuentes

2017-01-01

Full Text Available The steam reforming of ethanol (SRE on a bimetallic RhPt/CeO2 catalyst was evaluated by the integration of Response Surface Methodology (RSM and Aspen Plus (version 9.0, Aspen Tech, Burlington, MA, USA, 2016. First, the effect of the Rh–Pt weight ratio (1:0, 3:1, 1:1, 1:3, and 0:1 on the performance of SRE on RhPt/CeO2 was assessed between 400 to 700 °C with a stoichiometric steam/ethanol molar ratio of 3. RSM enabled modeling of the system and identification of a maximum of 4.2 mol H2/mol EtOH (700 °C with the Rh0.4Pt0.4/CeO2 catalyst. The mathematical models were integrated into Aspen Plus through Excel in order to simulate a process involving SRE, H2 purification, and electricity production in a fuel cell (FC. An energy sensitivity analysis of the process was performed in Aspen Plus, and the information obtained was used to generate new response surfaces. The response surfaces demonstrated that an increase in H2 production requires more energy consumption in the steam reforming of ethanol. However, increasing H2 production rebounds in more energy production in the fuel cell, which increases the overall efficiency of the system. The minimum H2 yield needed to make the system energetically sustainable was identified as 1.2 mol H2/mol EtOH. According to the results of the integration of RSM models into Aspen Plus, the system using Rh0.4Pt0.4/CeO2 can produce a maximum net energy of 742 kJ/mol H2, of which 40% could be converted into electricity in the FC (297 kJ/mol H2 produced. The remaining energy can be recovered as heat.

Distribution

Science.gov (United States)

John R. Jones

1985-01-01

Quaking aspen is the most widely distributed native North American tree species (Little 1971, Sargent 1890). It grows in a great diversity of regions, environments, and communities (Harshberger 1911). Only one deciduous tree species in the world, the closely related Eurasian aspen (Populus tremula), has a wider range (Weigle and Frothingham 1911)....

Ozone-induced H2O2 accumulation in field-grown aspen and birch is linked to foliar ultrastructure and peroxisomal activity

Science.gov (United States)

E. Oksanen; E. Häikiö; J. Sober; D.F. Karnosky

2003-01-01

Saplings of three aspen (Populus tremuloides) genotypes and seedlings of paper birch (Betula papyrifera) were exposed to elevated ozone (1.5x ambient) and 560 p.p.m. CO2, singly and in combination, from 1998 at the Aspen-FACE (free-air CO2 enrichment) site (Rhinelander, USA).

TreePics: visualizing trees with pictures

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Nicolas Puillandre

2017-09-01

Full Text Available While many programs are available to edit phylogenetic trees, associating pictures with branch tips in an efficient and automatic way is not an available option. Here, we present TreePics, a standalone software that uses a web browser to visualize phylogenetic trees in Newick format and that associates pictures (typically, pictures of the voucher specimens to the tip of each branch. Pictures are visualized as thumbnails and can be enlarged by a mouse rollover. Further, several pictures can be selected and displayed in a separate window for visual comparison. TreePics works either online or in a full standalone version, where it can display trees with several thousands of pictures (depending on the memory available. We argue that TreePics can be particularly useful in a preliminary stage of research, such as to quickly detect conflicts between a DNA-based phylogenetic tree and morphological variation, that may be due to contamination that needs to be removed prior to final analyses, or the presence of species complexes.

Insufficient Chilling Effects Vary among Boreal Tree Species and Chilling Duration

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Rongzhou Man

2017-08-01

Full Text Available Insufficient chilling resulting from rising winter temperatures associated with climate warming has been an area of particular interest in boreal and temperate regions where a period of cool temperatures in fall and winter is required to break plant dormancy. In this study, we examined the budburst and growth of trembling aspen (Populus tremuloides Michx., balsam poplar (Populus balsamifera L., white birch (Betula papyrifera Marsh., black spruce (Picea mariana (Mill. B.S.P., white spruce (Picea glauca (Moench Voss, jack pine (Pinus banksiana Lamb., and lodgepole pine (Pinus contorta Dougl. ex. Loud. seedlings subjected to typical northern Ontario, Canada, spring conditions in climate chambers after different exposures to natural chilling. Results indicate that chilling requirements (cumulative weighted chilling hours differed substantially among the seven species, ranging from 300 to 500 h for spruce seedlings to more than 1100 h for trembling aspen and lodgepole pine. Only spruce seedlings had fulfilled their chilling requirements before December 31, whereas the other species continued chilling well into March and April. Species with lower chilling requirements needed more heat accumulation for budburst and vice versa. Insufficient chilling delayed budburst but only extremely restricted chilling hours (<400 resulted in abnormal budburst and growth, including reduced needle and shoot expansion, early budburst in lower crowns, and erratic budburst on lower stems and roots. Effects, however, depended on both the species’ chilling requirements and the chilling–heat relationship. Among the seven tree species examined, trembling aspen is most likely to be affected by reduced chilling accumulation possible under future climate scenarios, followed by balsam poplar, white birch, lodgepole pine, and jack pine. Black and white spruce are least likely to be affected by changes in chilling hours.

Effects of elevated CO2 and ozone on phenolic glycosides of trembling aspen

Science.gov (United States)

James K. Nitao; Muraleedharan G. Nair; William J. Mattson; Daniel A. Herms; Bruce A. Birr; Mark D. Coleman; Terry M. Trier; J. G. Isebrands

1996-01-01

We tested the effects of elevated CO2 and ozone on concentrations of the phenolic glycosides salicortin and tremulacin in immature and mature foliage of the trembling aspen (Populus tremuloides) clones 216, 259, and 271.

Vegetation of birch and aspen forests in the Pinega State Reserve

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Sergey Yu. Popov

2017-05-01

Full Text Available The Pinega State Nature Reserve (Russia is located in the Arkhangelsk region in the northern taiga subzone. Together with spruce forests and mires, birch forests represent one of the most wide-spread plant communities of its territory. Birch forests cover 24.6% of the Reserve's area. Aspen forests are rare plant communities in the Pinega Reserve. These forests cover only 0.9% of the whole Reserve's area. The birch and aspen forests vegetation has been classified based on 82 relevès. Eleven associations could be distinguished, which represent six groups of associations. Detailed characteristics of these syntaxa are provided including their biodiversity analysis. The analysis allowed establishing that the revealed syntaxa differ in relation to habitat environmental conditions: e.g., soil moisture, trophicity, nitrogen saturation and soil acidity. Sphagnum and blueberry birch forests proved to be the poorest in nitrogen, in contrast to the richest humidoherbaceous and broad-grassed groups of birch forest associations. Broad-grassed birch forests in the Pinega Reserve inhabit the most drained locations, while humidoherbaceous and Sphagnum forests occur in lesser drained locations.

The role of phytochrome A and gibberellins in growth under long and short day conditions: Studies in hybrid aspen

Energy Technology Data Exchange (ETDEWEB)

Eriksson, M.E. [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden). Dept. of Forest Genetics and Plant Physiology

2000-07-01

This thesis addresses questions concerning the regulation of growth and, specifically, the cessation of growth in response to short days in deciduous tree species. The model tree used in the studies was hybrid aspen (Populus tremula L. x P. tremuloides Michx.). We have exploited the possibility of transforming this species to modulate the level of expression of target genes using over-expression and antisense techniques. The target genes in the studies were the photoreceptor phytochrome A (phyA) and gibberellin 20-oxidase (GA 20-oxidase), the latter being a highly regulated enzyme involved in the biosynthesis of gibberellins (GAs). The photoreceptor phyA has been implicated in photoperiodic regulation of growth, while GAs may regulate the physiological response further downstream. The endogenous expression of these genes has been investigated in parallel with studies of various plants with ectopic and reduced levels of expression. The main focus has been on the early stages of induction of growth cessation and its physiological and molecular mechanisms. Studies of hybrid aspen plants with an increased or reduced expression of phyA, show this receptor to mediate the photoperiodic regulation of growth. Plants with ectopic expression could not stop growing despite drastically shortened photoperiods, while the antisense plants showed the reverse phenotype, with a higher sensitivity resulting in earlier cessation of growth. The role of GAs in growth inhibition was also addressed using plants with a reduction in GA levels. These plants showed early cessation of growth and dormancy, and thus an increased sensitivity toward daylength. Conversely, plants with increased rates of GA biosynthesis showed increased growth and stopped growing much later. Furthermore, increases in GA biosynthesis, resulting in high levels of GAs have a major impact on growth. Plants with high GA levels have increased elongation and diameter growth, due to higher rates of cell production in the

Phylogenetic trees

OpenAIRE

Baños, Hector; Bushek, Nathaniel; Davidson, Ruth; Gross, Elizabeth; Harris, Pamela E.; Krone, Robert; Long, Colby; Stewart, Allen; Walker, Robert

2016-01-01

We introduce the package PhylogeneticTrees for Macaulay2 which allows users to compute phylogenetic invariants for group-based tree models. We provide some background information on phylogenetic algebraic geometry and show how the package PhylogeneticTrees can be used to calculate a generating set for a phylogenetic ideal as well as a lower bound for its dimension. Finally, we show how methods within the package can be used to compute a generating set for the join of any two ideals.

Aging in a long-lived clonal tree.

Directory of Open Access Journals (Sweden)

Dilara Ally

2010-08-01

Full Text Available From bacteria to multicellular animals, most organisms exhibit declines in survivorship or reproductive performance with increasing age ("senescence". Evidence for senescence in clonal plants, however, is scant. During asexual growth, we expect that somatic mutations, which negatively impact sexual fitness, should accumulate and contribute to senescence, especially among long-lived clonal plants. We tested whether older clones of Populus tremuloides (trembling aspen from natural stands in British Columbia exhibited significantly reduced reproductive performance. Coupling molecular-based estimates of clone age with male fertility data, we observed a significant decline in the average number of viable pollen grains per catkin per ramet with increasing clone age in trembling aspen. We found that mutations reduced relative male fertility in clonal aspen populations by about 5.8 x 10(-5 to 1.6 x 10(-3 per year, leading to an 8% reduction in the number of viable pollen grains, on average, among the clones studied. The probability that an aspen lineage ultimately goes extinct rises as its male sexual fitness declines, suggesting that even long-lived clonal organisms are vulnerable to senescence.

Liquefaction of aspen poplar wood

Energy Technology Data Exchange (ETDEWEB)

Eager, R L; Mathews, J F; Pepper, J M

1982-01-01

Dried and green aspen poplar wood suspended in water containing alkali catalysts was converted completely to an oil, water-soluble chemical, and gases by heating for 1 hour in the presence of CO in a rocking batch reactor. Within the ranges of parameters studied: temperature of 593-633 K; nominal reaction times of less than or equal to 1 hour; water-to-wood ratio of 0.5:1-5:1; Na/sub 2/CO/sub 3/, K/sub 2/CO/sub 3/, and NaOH catalysts; amount of catalyst 7.0-12.5%; and initial H-CO ratios of 2:1-0:1, the water-to-wood ratio was most important. Oil yields of approximately 50% with a C plus H content of approximately 80% and representing a C recovery of approximately 66% were obtained. The higher heats of combustion were 32.2-36.0 MJ/kg.

Results of growing relatively smoke resistant types of trees and their practical use. [German Democratic Republic

Energy Technology Data Exchange (ETDEWEB)

Tzschacksch, O.

1985-01-01

Achievements in cultivating sulfur dioxide resistant conifers in the German Democratic Republic are summarized. These conifers will be planted in afforestation programs in smoke damage zones I, i.e. in conifer forests at high elevations with maximum pollution damage. Nurseries with the most promising tree types have been established for harvesting seeds for propagation. Cultivation of cuttings and tree grafting is carried out in experimental nurseries along with laboratory gas treatment tests. Smoke resistant varieties of the common spruce Picae abies (L.) show vigorous growth in smoke damage zone I. Other spruce types suitable for cultivation are Picea pungens Engelm., Picea omorica (Panc.) Purk. with the highest vitality in 15 to 20 year old trial plantings in smoke damage zone I extreme, and Picea glanca, rubens and orientalis. Suitable pines are Pinus contorta Dougl. ex Loud. (Murray pine), Pinus mugo Turra, and others; resistant larches are Larix decidua and Larix leptolepis. Deciduous trees being cultivated for afforestation are aspens (Populus tremula L.) and mountain ash (Sorbus aucuparia L.). 11 references.

Simulation of a tubular solid oxide fuel cell stack using AspenPlusTM unit operation models

International Nuclear Information System (INIS)

Zhang, W.; Croiset, E.; Douglas, P.L.; Fowler, M.W.; Entchev, E.

2005-01-01

The design of a fuel cell system involves both optimization of the fuel cell stack and the balance of plant with respect to efficiency and economics. Many commercially available process simulators, such as AspenPlus TM , can facilitate the analysis of a solid oxide fuel cell (SOFC) system. A SOFC system may include fuel pre-processors, heat exchangers, turbines, bottoming cycles, etc., all of which can be very effectively modelled in process simulation software. The current challenge is that AspenPlus TM or any other commercial process simulators do not have a model of a basic SOFC stack. Therefore, to enable performing SOFC system simulation using one of these simulators, one must construct an SOFC stack model that can be implemented in them. The most common approach is to develop a complete SOFC model in a programming language, such as Fortran, Visual Basic or C++, first and then link it to a commercial process simulator as a user defined model or subroutine. This paper introduces a different approach to the development of a SOFC model by utilizing existing AspenPlus TM functions and existing unit operation modules. The developed ''AspenPlus TM SOFC'' model is able to provide detailed thermodynamic and parametric analyses of the SOFC operation and can easily be extended to study the entire power plant consisting of the SOFC and the balance of plant without the requirement for linking with other software. Validation of this model is performed by comparison to a Siemens-Westinghouse 100 kW class tubular SOFC stack. Sensitivity analyses of major operating parameters, such as utilization factor (U f ), current density (I c ) and steam-carbon ratio (S/C), were performed using the developed model, and the results are discussed in this paper

Preliminary Investigation into Tree Dryness in Hevea brasiliensis (Wild. Ex Adr. De Juss Muell. Arg. by Path Analysis of Tree Dryness and Latex Parameters

Directory of Open Access Journals (Sweden)

Omokhafe, KO.

2001-01-01

Full Text Available The correlative path analysis between tree dryness and four latex parameters was studied in eleven clones of Hevea brasiliensis. The latex parameters used for evaluation were initial volume, initial flow rate, final volume and plugging index with tree dryness as the dependent factor. Estimates of direct and indirect effects of each of the latex parameters on tree dryness were calculated through linear correlation and path analysis. The correlation coefficient between initial volume and initial flow rate was 1.00 and both characters had the same correlation coefficients with other latex parameters and tree dryness. This implies that initial volume and initial flow rate are alternatives for evaluation of correlation between latex parameters and tree dryness. There was significant correlation between initial volume, initial flow rate and tree dryness at V = -0.52 and high indirect effect of initial volume and initial flow rate through final volume. In addition, despite the low correlation coefficient of V = -0.20 between final volume and tree dryness, the direct effect of final volume on tree dryness was high at 0.812. Final volume is therefore an important factor in the incidence of tree dryness.

77 FR 60373 - Monroe Mountain Aspen Ecosystems Restoration Project Fishlake National Forest; Sevier and Piute...

Science.gov (United States)

2012-10-03

....u s. In addition, an Open House will be held at the Sevier County Administrative Building in... continual maintenance, fencing is not a long term sustainable response option for protecting aspen sprouts...

Is the wide distribution of aspen a result of its stress tolerance?

Science.gov (United States)

V. J. Lieffers; S. M. Landhausser; E. H. Hogg

2001-01-01

Populus tremuloides is distributed from drought-prone fringes of the Great Plains to extremely cold sites at arctic treeline. To occupy these conditions aspen appears to be more tolerant of stress than the other North American species of the genus Populus. Cold winters, cold soil conditions during the growing season, periodic drought, insect defoliation, and...

Testing a hydraulic trait based model of stomatal control: results from a controlled drought experiment on aspen (Populus tremuloides, Michx.) and ponderosa pine (Pinus ponderosa, Douglas)

Science.gov (United States)

Love, D. M.; Venturas, M.; Sperry, J.; Wang, Y.; Anderegg, W.

2017-12-01

Modeling approaches for tree stomatal control often rely on empirical fitting to provide accurate estimates of whole tree transpiration (E) and assimilation (A), which are limited in their predictive power by the data envelope used to calibrate model parameters. Optimization based models hold promise as a means to predict stomatal behavior under novel climate conditions. We designed an experiment to test a hydraulic trait based optimization model, which predicts stomatal conductance from a gain/risk approach. Optimal stomatal conductance is expected to maximize the potential carbon gain by photosynthesis, and minimize the risk to hydraulic transport imposed by cavitation. The modeled risk to the hydraulic network is assessed from cavitation vulnerability curves, a commonly measured physiological trait in woody plant species. Over a growing season garden grown plots of aspen (Populus tremuloides, Michx.) and ponderosa pine (Pinus ponderosa, Douglas) were subjected to three distinct drought treatments (moderate, severe, severe with rehydration) relative to a control plot to test model predictions. Model outputs of predicted E, A, and xylem pressure can be directly compared to both continuous data (whole tree sapflux, soil moisture) and point measurements (leaf level E, A, xylem pressure). The model also predicts levels of whole tree hydraulic impairment expected to increase mortality risk. This threshold is used to estimate survivorship in the drought treatment plots. The model can be run at two scales, either entirely from climate (meteorological inputs, irrigation) or using the physiological measurements as a starting point. These data will be used to study model performance and utility, and aid in developing the model for larger scale applications.

Soil properties and aspen development five years after compaction and forest floor removal

Science.gov (United States)

Douglas M. Stone; John D. Elioff

1998-01-01

Forest management activities that decrease soil porosity and remove organic matter have been associated with declines in site productivity. In the northern Lake States region, research is in progress in the aspen (Populus tremuloides Michx. and P. grandidentata Michx.) forest type to determine effects of soil compaction and organic...

Prehydrolysis of aspen wood with water and with dilute aqueous sulfuric acid

Science.gov (United States)

Edward L. Springer; John F. Harris

1982-01-01

Water prehydrolysis of aspen wood was compared with 0.40% sulfuric acid prehydrolysis at a reaction temperature of 170°C. Acid prehydrolysis gave much higher yields of total anhydroxylose units in the prehydrolyzate and removed significantly less anhydroglucose from the wood than did the water treatment. At maximum yields of total anhydroxylose units in the...

The Future of Community and Personal Identity in the Coming Electronic Culture. A Report of the Annual Aspen Institute Roundtable on Information Technology (3rd, Aspen, Colorado, August 18-21, 1994).

Science.gov (United States)

Bollier, David

The 1994 Aspen Institute Roundtable on Information Technology began as a look at the changing nature of the home. In building scenarios of the "new home," the participants expressed many significant insights into issues of personal identity, community-building, and setting boundaries in our lives and environments. This report captures…

Model estimates of leaf area and reference canopy stomatal conductance suggest correlation between phenology and physiology in both trembling aspen and red pine

Science.gov (United States)

Mackay, D. S.; Ewers, B. E.; Kruger, E. L.

2006-12-01

Phenological variations impact water and carbon fluxes, as evidenced by the large interannual variability of net ecosystem exchange of carbon dioxide and evapotranspiration (ET). In northern Wisconsin we observed daily variations of canopy transpiration from hardwoods from 1.0 to 1.7 mm/day during the leaf unfolding period and 1.7 to 2.6 mm/day with leaves fully out. Correlations between such flux rates and phenology have not been extensively tested and mechanistic connections are in their infancy. Some data suggest that stomatal conductance and photosynthesis increases up to full expansion. Moreover, in conifers, the interaction of phenology and physiology is more complicated than in deciduous trees because needles are retained for several years. Using inverse modeling with a coupled photosynthesis-transpiration model we estimated reference canopy stomatal conductance, Gsref, for red pine (Pinus resinosa), and Gsref and leaf area index, L, for trembling aspen (Populus tremuloides), using 30-min continuous sap flux data spanning a period from just prior to the start of leaf expansion to just after leaf senescence. The red pine showed Gsref ramp up from 105 to 179 mmol m-2 leaf s-1, which represented a 37 to 50 percent increase in Gsref after accounting for maximum possible changes in L. After full leaf out, the trembling aspen were almost immediately defoliated, and then reflushed after three weeks. Model estimates of L reflected this pattern and were consistent with measurements. However, Gsref never exceeded 45 mmol m-2 s-1 prior to defoliation, but peaked at 112 mmol m-2 s-1 after reflushing. These results support the need for further work that aims to separate phenology and physiology.

Preparation of Highly Porous Binderless Active Carbon Monoliths from Waste Aspen Sawdust

Directory of Open Access Journals (Sweden)

Dawei Li

2014-01-01

Full Text Available Waste aspen sawdust was used as a precursor to prepare binderless active carbon monoliths (ACMs with high porosities. The ACMs were prepared by activation with H3PO4 at different activation temperatures (500 to 700 °C and retention times (1 to 3 h. Their morphologies, yields, textural properties, and microcrystalline structures were investigated using scanning electron microscopy (SEM, an analytical balance, N2 adsorption/desorption techniques, and X-ray diffraction (XRD. The results indicated that waste aspen sawdust could be successfully converted into highly porous binderless ACMs. The apparent specific surface area (SSA and yield of ACMs were in the range of 688 to 951 m2/g and 26.6 to 36.2%, respectively. Highly microporous ACMs with a micropore percentage of 91.1%, apparent specific surface area of 951 m2/g, pore volume of 0.481 mL/g, and bulk density of 0.56 g/mL could be produced by activation at 700 °C for 1 h. Increasing the activation temperature or retention time increased the specific surface area, pore volume, and turbostratic degree, but decreased the yield.

Effects of long-term (10 years) exposure to elevated CO2 and O3 on trembling Aspen carbon and nitrogen metabolism at the aspen FACE (Free-Air Carbon Dioxide Enrichment) study site

Science.gov (United States)

Rakesh Minocha; Stephanie Long; Subhash Minocha; Paula Marquardt; Neil Nelson; Mark. Kubiske

2010-01-01

This study was conducted at the Aspen Free-Air Carbon Dioxide Enrichment (FACE) experimental site, Rhinelander, WI, (USA). Since 1998, 12 experimental rings planted in 1997 underwent four different treatments: control; elevated CO2 (560 ppm); elevated O3 (1.5X ambient) and elevated CO2 (560 ppm) + O...

Modelling and testing the performance of a commercial ammonia/water absorption chiller using Aspen-Plus platform

International Nuclear Information System (INIS)

Mansouri, Rami; Boukholda, Ismail; Bourouis, Mahmoud; Bellagi, Ahmed

2015-01-01

A steady-state simulation model of a commercial 3-ton ammonia/water absorption chiller is developed and validated using the flow-sheeting software Aspen-Plus. First an appropriate thermodynamic property model for the ammonia/water fluid mixture is selected. To this purpose nine methods from the software library are pre-selected and tested, but none of the methods predicts the VLE (vapour–liquid equilibrium) with sufficient accuracy. The interaction parameters of these models are then determined by fitting the equations of state (EOS) to VLE data. It is finally found that the Boston–Mathias modified Peng–Robinson EOS with fitted parameters predicts most accurately the VLE for the temperature and pressure ranges encountered in commercial chillers. A simulation model of the machine is then developed. The simulation results are found to be in good agreement with data from literature at a cooling air temperature of 35 ºC. The heat transfer characteristics (UA) of the various heat exchangers of the machine are then determined and the model modified to make it accept these (UA) as input parameters. The comparison of the simulation predictions at cooling air temperatures of 26.7 and 38 ºC with the bibliographical data showed good concordance. The proposed model could be very useful for the analysis and performance prediction of the commercial absorption chiller. - Highlights: • A commercial NH 3 /H 2 O absorption chiller is simulated using the software Aspen-Plus. • Peng-Robinson-Boston-Mathias equation of state is used to predict VLE of NH 3 /H 2 O fluid mixture. • A steady-state model describing the chiller operation is developed. • The model predicts the internal operating conditions and COP of the chiller.

Modelling and Simulation of Gas Engines Using Aspen HYSYS

Directory of Open Access Journals (Sweden)

M. C. Ekwonu

2013-12-01

Full Text Available In this paper gas engine model was developed in Aspen HYSYS V7.3 and validated with Waukesha 16V275GL+ gas engine. Fuel flexibility, fuel types and part load performance of the gas engine were investigated. The design variability revealed that the gas engine can operate on poor fuel with low lower heating value (LHV such as landfill gas, sewage gas and biogas with biogas offering potential integration with bottoming cycles when compared to natural gas. The result of the gas engine simulation gave an efficiency 40.7% and power output of 3592kW.

Continental-scale assessment of genetic diversity and population structure in quaking aspen (Populus tremuloides)

Science.gov (United States)

Colin M. Callahan; Carol A. Rowe; Ronald J. Ryel; John D. Shaw; Michael D. Madritch; Karen E. Mock

2013-01-01

Aspen populations in the south-western portion of the range are consistent with expectations for a historically stable edge, with low within-population diversity, significant geographical population structuring, and little evidence of northward expansion. Structuring within the southwestern cluster may result from distinct gene pools separated during the Pleistocene...

Organo-mineral interactions promote greater soil organic carbon stability under aspen in semi-arid montane forests in Utah

Science.gov (United States)

Van Miegroet, H.; Roman Dobarco, M.

2014-12-01

Forest species influence soil organic carbon (SOC) storage through litter input, which in interaction with soil microclimate, texture and mineralogy, lead to different SOC stabilization and storage patterns. We sampled mineral soil (0-15 cm) across the ecotone between aspen (Populus tremuloides) and mixed conifers stands (Abies lasiocarpa and Pseudotsuga menziesii) in semi-arid montane forests from Utah, to investigate the influence of vegetation vs. site characteristics on SOC stabilization, storage and chemistry. SOC was divided into light fraction (LF), mineral-associated SOC in the silt and clay fraction (MoM), and a dense subfraction > 53 μm (SMoM) using wet sieving and electrostatic attraction. SOC decomposability and solubility was derived from long term laboratory incubations and hot water extractions (HWE). Fourier transform infrared spectroscopy (FTIR) was used to study differences in chemical functional groups in LF and MoM. Vegetation cover did not affect SOC storage (47.0 ± 16.5 Mg C ha-1), SOC decomposability (cumulative CO2-C release of 93.2 ± 65.4 g C g-1 C), or SOC solubility (9.8 ± 7.2 mg C g-1 C), but MoM content increased with presence of aspen [pure aspen (31.2 ± 15.1 Mg C ha-1) > mixed (25.7 ± 8.8 Mg C ha-1) > conifer (22.8 ± 9.0 Mg C ha-1)]. Organo-mineral complexes reduced biological availability of SOC, indicated by the negative correlation between silt+clay (%) and decomposable SOC per gram of C (r = -0.48, p = 0.001) or soluble SOC (r = -0.59, p plant or microbial origin. FTIR spectra clustered by sites with similar parent material rather than by vegetation cover. This suggests that initial differences in litter chemistry between aspen and conifers converged into similar MoM chemistry within sites.

The effect of warming and enhanced ultraviolet radiation on gender-specific emissions of volatile organic compounds from European aspen

Energy Technology Data Exchange (ETDEWEB)

Maja, Mengistu M., E-mail: mengistu.maja@uef.fi [University of Eastern Finland, Department of Environmental Science, P.O.Box 1627, 70211 Kuopio (Finland); Kasurinen, Anne; Holopainen, Toini [University of Eastern Finland, Department of Environmental Science, P.O.Box 1627, 70211 Kuopio (Finland); Julkunen-Tiitto, Riitta [University of Eastern Finland, Department of Biology, P.O. Box 111, 80101 Joensuu (Finland); Holopainen, Jarmo K. [University of Eastern Finland, Department of Environmental Science, P.O.Box 1627, 70211 Kuopio (Finland)

2016-03-15

Different environmental stress factors often occur together but their combined effects on plant secondary metabolism are seldom considered. We studied the effect of enhanced ultraviolet (UV-B) (31% increase) radiation and temperature (ambient + 2 °C) singly and in combination on gender-specific emissions of volatile organic compounds (VOCs) from 2-year-old clones of European aspen (Populus tremula L.). Plants grew in 36 experimental plots (6 replicates for Control, UV-A, UV-B, T, UV-A + T and UV-B + T treatments), in an experimental field. VOCs emitted from shoots were sampled from two (1 male and 1 female) randomly selected saplings (total of 72 saplings), per plot on two sampling occasions (June and July) in 2014. There was a significant UV-B × temperature interaction effect on emission rates of different VOCs. Isoprene emission rate was increased due to warming, but warming also modified VOC responses to both UV-A and UV-B radiation. Thus, UV-A increased isoprene emissions without warming, whereas UV-B increased emissions only in combination with warming. Warming-modified UV-A and UV-B responses were also seen in monoterpenes (MTs), sesquiterpenes (SQTs) and green leaf volatiles (GLVs). MTs showed also a UV × gender interaction effect as females had higher emission rates under UV-A and UV-B than males. UV × gender and T × gender interactions caused significant differences in VOC blend as there was more variation (more GLVs and trans-β-caryophyllene) in VOCs from female saplings compared to male saplings. VOCs from the rhizosphere were also collected from each plot in two exposure seasons, but no significant treatment effects were observed. Our results suggest that simultaneous warming and elevated-UV-radiation increase the emission of VOCs from aspen. Thus the contribution of combined environmental factors on VOC emissions may have a greater impact to the photochemical reactions in the atmosphere compared to the impact of individual factors acting alone

The effect of warming and enhanced ultraviolet radiation on gender-specific emissions of volatile organic compounds from European aspen

International Nuclear Information System (INIS)

Maja, Mengistu M.; Kasurinen, Anne; Holopainen, Toini; Julkunen-Tiitto, Riitta; Holopainen, Jarmo K.

2016-01-01

Different environmental stress factors often occur together but their combined effects on plant secondary metabolism are seldom considered. We studied the effect of enhanced ultraviolet (UV-B) (31% increase) radiation and temperature (ambient + 2 °C) singly and in combination on gender-specific emissions of volatile organic compounds (VOCs) from 2-year-old clones of European aspen (Populus tremula L.). Plants grew in 36 experimental plots (6 replicates for Control, UV-A, UV-B, T, UV-A + T and UV-B + T treatments), in an experimental field. VOCs emitted from shoots were sampled from two (1 male and 1 female) randomly selected saplings (total of 72 saplings), per plot on two sampling occasions (June and July) in 2014. There was a significant UV-B × temperature interaction effect on emission rates of different VOCs. Isoprene emission rate was increased due to warming, but warming also modified VOC responses to both UV-A and UV-B radiation. Thus, UV-A increased isoprene emissions without warming, whereas UV-B increased emissions only in combination with warming. Warming-modified UV-A and UV-B responses were also seen in monoterpenes (MTs), sesquiterpenes (SQTs) and green leaf volatiles (GLVs). MTs showed also a UV × gender interaction effect as females had higher emission rates under UV-A and UV-B than males. UV × gender and T × gender interactions caused significant differences in VOC blend as there was more variation (more GLVs and trans-β-caryophyllene) in VOCs from female saplings compared to male saplings. VOCs from the rhizosphere were also collected from each plot in two exposure seasons, but no significant treatment effects were observed. Our results suggest that simultaneous warming and elevated-UV-radiation increase the emission of VOCs from aspen. Thus the contribution of combined environmental factors on VOC emissions may have a greater impact to the photochemical reactions in the atmosphere compared to the impact of individual factors acting alone

2012 Aspen Winter Conference New Paradigms for Low-Dimensional Electronic Materials, February 5-10, 2012

Energy Technology Data Exchange (ETDEWEB)

Moore, Joel; Rabe, Karin; Nayak, Chetan; Troyer, Matthias

2012-05-01

Aspen Center for Physics Project Summary DOE Budget Period: 10/1/2011 to 9/30/2012 Contract # DE-SC0007479 New Paradigms for Low-Dimensional Electronic Materials The 2012 Aspen Winter Conference on Condensed Matter Physics was held at the Aspen Center for Physics from February 5 to 10, 2012. Seventy-four participants from seven countries, and several universities and national labs attended the workshop titled, New Paradigms for Low-Dimensional Electronic Materials. There were 34 formal talks, and a number of informal discussions held during the week. Talks covered a variety of topics related to DOE BES priorities, including, for example, advanced photon techniques (Hasan, Abbamonte, Orenstein, Shen, Ghosh) and predictive theoretical modeling of materials properties (Rappe, Pickett, Balents, Zhang, Vanderbilt); the full conference schedule is provided with this report. The week's events included a public lecture (Quantum Matters given by Chetan Nayak from Microsoft Research) and attended by 234 members of the public, and a physics caf© geared for high schoolers that is a discussion with physicists conducted by Kathryn Moler (Stanford University) and Andrew M. Rappe (University of Pennsylvania) and attended by 67 locals and visitors. While there were no published proceedings, some of the talks are posted online and can be Googled. The workshop was organized by Joel Moore (University of California Berkeley), Chetan Nayak (Microsoft Research), Karin Rabe (Rutgers University), and Matthias Troyer (ETH Zurich). Two organizers who did not attend the conference were Gabriel Aeppli (University College London & London Centre for Nanotechnology) and Andrea Cavalleri (Oxford University & Max Planck Hamburg).

Microscale Ocean Biophysics, Aspen Center for Physics: January 11-16 2015

Science.gov (United States)

2017-04-19

dissolved   organic  matter  persist  in  the  deep  ocean:  Is  the  solution   dilution ?”     8.45  –  Kwangmin  Son...AUTHORS 7. PERFORMING ORGANIZATION NAMES AND ADDRESSES 15. SUBJECT TERMS b. ABSTRACT 2. REPORT TYPE 17. LIMITATION OF ABSTRACT 15. NUMBER OF PAGES...Microscale Ocean Biophysics, Aspen Center for Physics, January 11-16, 2015 Microscopic organisms control ocean processes at global scales. However

Standardized Competencies for Parenteral Nutrition Order Review and Parenteral Nutrition Preparation, Including Compounding: The ASPEN Model.

Science.gov (United States)

Boullata, Joseph I; Holcombe, Beverly; Sacks, Gordon; Gervasio, Jane; Adams, Stephen C; Christensen, Michael; Durfee, Sharon; Ayers, Phil; Marshall, Neil; Guenter, Peggi

2016-08-01

Parenteral nutrition (PN) is a high-alert medication with a complex drug use process. Key steps in the process include the review of each PN prescription followed by the preparation of the formulation. The preparation step includes compounding the PN or activating a standardized commercially available PN product. The verification and review, as well as preparation of this complex therapy, require competency that may be determined by using a standardized process for pharmacists and for pharmacy technicians involved with PN. An American Society for Parenteral and Enteral Nutrition (ASPEN) standardized model for PN order review and PN preparation competencies is proposed based on a competency framework, the ASPEN-published interdisciplinary core competencies, safe practice recommendations, and clinical guidelines, and is intended for institutions and agencies to use with their staff. © 2016 American Society for Parenteral and Enteral Nutrition.

Effect of steam treatment on the hydrolysis of aspen by commerical enzymes

Energy Technology Data Exchange (ETDEWEB)

Macdonald, D G; Mathews, J F

1979-06-01

Steam treatment renders aspen wood more susceptible to hydrolysis by commerical enzyme preparations such as the Onozuka variety. The main products of enzymatic hydrolysis are glucose, xylose, and xylobiose. Cellobiose may have been another product but it could not be measured due to interference by lactose, a sugar found in the enzyme. The hemicellulose fraction of the wood is relatively more rapidly hydrolyzed by the enzymes than the cellulose fraction.

Phosphate removal by refined aspen wood fiber treated with carboxymethyl cellulose and ferrous chloride

Science.gov (United States)

Thomas L. Eberhardt; Soo-Hong Min; James S. Han

2006-01-01

Biomass-based filtration media are of interest as an economical means to remove pollutants and nutrients found in stormwater runoff. Refined aspen wood fiber samples treated with iron salt solutions demonstrated limited capacities to remove (ortho)phosphate from test solutions. To provide additional sites for iron complex formation, and thereby impart a greater...

WAMCUT, a computer code for fault tree evaluation. Final report

International Nuclear Information System (INIS)

Erdmann, R.C.

1978-06-01

WAMCUT is a code in the WAM family which produces the minimum cut sets (MCS) for a given fault tree. The MCS are useful as they provide a qualitative evaluation of a system, as well as providing a means of determining the probability distribution function for the top of the tree. The program is very efficient and will produce all the MCS in a very short computer time span. 22 figures, 4 tables

Effect of citric acid modification of aspen wood on sorption of copper ion

Science.gov (United States)

James D. McSweeny; Roger M. Rowell; Soo Hong Min

2006-01-01

Milled aspen wood was thermochemically modified with citric acid for the purpose of improving the copper (Cu2+) ion sorption capacity of the wood when tested in 24-hour equilibrium batch tests. The wood-citric acid adducts provided additional carboxyl groups to those in the native wood and substantially increased Cu2+ ion uptake of the modified wood compared with that...

Refining discordant gene trees.

Science.gov (United States)

Górecki, Pawel; Eulenstein, Oliver

2014-01-01

Evolutionary studies are complicated by discordance between gene trees and the species tree in which they evolved. Dealing with discordant trees often relies on comparison costs between gene and species trees, including the well-established Robinson-Foulds, gene duplication, and deep coalescence costs. While these costs have provided credible results for binary rooted gene trees, corresponding cost definitions for non-binary unrooted gene trees, which are frequently occurring in practice, are challenged by biological realism. We propose a natural extension of the well-established costs for comparing unrooted and non-binary gene trees with rooted binary species trees using a binary refinement model. For the duplication cost we describe an efficient algorithm that is based on a linear time reduction and also computes an optimal rooted binary refinement of the given gene tree. Finally, we show that similar reductions lead to solutions for computing the deep coalescence and the Robinson-Foulds costs. Our binary refinement of Robinson-Foulds, gene duplication, and deep coalescence costs for unrooted and non-binary gene trees together with the linear time reductions provided here for computing these costs significantly extends the range of trees that can be incorporated into approaches dealing with discordance.

Urbanization-related changes in European aspen (Populus tremula L.): Leaf traits and litter decomposition

International Nuclear Information System (INIS)

Nikula, Suvi; Vapaavuori, Elina; Manninen, Sirkku

2010-01-01

We investigated foliar and litter responses of European aspen (Populus tremula L.) to urbanization, including factors such as increased temperature, moisture stress and nitrogen (N) deposition. Leaf samples were collected in 2006-2008 from three urban and three rural forest stands in the Helsinki Metropolitan Area, southern Finland, and reciprocal litter transplantations were established between urban and rural sites. Urban leaves exhibited a higher amount of epicuticular waxes and N concentration, and a lower C:N ratio than rural ones, but there was no difference in specific leaf area. Urban litter had a slightly higher N concentration, lower concentrations of lignin and total phenolics, and was more palatable to a macrofaunal decomposer. Moreover, litter decay was faster at the urban site and for urban litter. Urbanization thus resulted in foliar acclimatization in terms of increased amount of epicuticular waxes, as well as in accelerated decomposition of the N-richer leaf litter. - Urbanization can modify leaf traits of aspen and accelerate litter decomposition through changes in litter traits as well as in environmental conditions at the decomposition site.

Making CSB + -Trees Processor Conscious

DEFF Research Database (Denmark)

Samuel, Michael; Pedersen, Anders Uhl; Bonnet, Philippe

2005-01-01

of the CSB+-tree. We argue that it is necessary to consider a larger group of parameters in order to adapt CSB+-tree to processor architectures as different as Pentium and Itanium. We identify this group of parameters and study how it impacts the performance of CSB+-tree on Itanium 2. Finally, we propose......Cache-conscious indexes, such as CSB+-tree, are sensitive to the underlying processor architecture. In this paper, we focus on how to adapt the CSB+-tree so that it performs well on a range of different processor architectures. Previous work has focused on the impact of node size on the performance...... a systematic method for adapting CSB+-tree to new platforms. This work is a first step towards integrating CSB+-tree in MySQL’s heap storage manager....

Figured grain in aspen is heritable and not affected by graft-transmissible signals

Science.gov (United States)

Youran Fan; Kendal Rupert; Alex C. Wiedenhoeft; Keith Woeste; Christian Lexer; Richard. Meilan

2013-01-01

Figure can add value to wood products, but its occurrence is unpredictable. A first step in reliably producing figured wood is determining whether it is faithfully transmitted to progeny via sexual and asexual reproduction. We describe a 26-year-old male aspen genotype, designated ‘Curly Poplar’, which was shown to be a Populus × canescens hybrid using microsatellite...

Using Aspen to Teach Chromatographic Bioprocessing: A Case Study in Weak Partitioning Chromatography for Biotechnology Applications

Science.gov (United States)

Evans, Steven T.; Huang, Xinqun; Cramer, Steven M.

2010-01-01

The commercial simulator Aspen Chromatography was employed to study and optimize an important new industrial separation process, weak partitioning chromatography. This case study on antibody purification was implemented in a chromatographic separations course. Parametric simulations were performed to investigate the effect of operating parameters…

Polypropylene /Aspen/ liquid polybutadienes composites: maximization of impact strength, tensile and modulus by statistical experimental design

Czech Academy of Sciences Publication Activity Database

Kokta, B. V.; Fortelný, Ivan; Kruliš, Zdeněk; Horák, Zdeněk; Michálková, Danuše

2005-01-01

Roč. 99, - (2005), s. 10-11 ISSN 0009-2770. [International Conference on Polymeric Materials in Automotive , Slovak Rubber Conference /17./. 10.5.2005-12.5.2005, Bratislava] Institutional research plan: CEZ:AV0Z40500505 Keywords : polypropylene * Aspen-PP composite Subject RIV: CD - Macromolecular Chemistry

ASPEN+ and economic modeling of equine waste utilization for localized hot water heating via fast pyrolysis

Science.gov (United States)

ASPEN Plus based simulation models have been developed to design a pyrolysis process for the on-site production and utilization of pyrolysis oil from equine waste at the Equine Rehabilitation Center at Morrisville State College (MSC). The results indicate that utilization of all available Equine Reh...

Utilization of steam- and explosion-decompressed aspen wood by some anaerobes

Energy Technology Data Exchange (ETDEWEB)

Khan, A W; Asther, M; Giuliano, C

1984-01-01

Tests made to study the suitability of using steam- and explosion-decompressed aspen wood as a substrate in anaerobic fermentations indicated that after washing with dilute NaOH it becomes less than 80% accessible to both mesophilic and thermophilic cellulolytic anaerobes and cellulases, compared with delignified, ball-milled pulp. After washing, this material was also suitable for the single-step conversion of cellulose to EtOH using cocultures consisting of cellulolytic and EtOH-producing saccharolytic anaerobes; and without and after washing by the use of cellulolytic enzymes and ethanologenic anaerobes.

Response of a forest ecotone to ionizing radiation. Progress report, October 15, 1979-October 14, 1980

International Nuclear Information System (INIS)

Murphy, P.G.; Sharitz, R.R.

1980-07-01

Compositional and structural characteristics of three forest types, including aspen dominated, maple-birch dominated, and an intervening ecotone, were studied before and after irradiation in northern Wisconsin. Irradiation occurred during the summer of 1972. By the summer of 1973 the density of viable tree seedlings at 10 m from the radiation source was substantially reduced in all three areas relative to the preirradiation densities of 1971. As of the summer of 1979, establishment of tree seedlings continued to be inhibited by the vigorous development of ground vegetation. In most respects, the ecotone has shown properties and responses to radiation intermediate to those observed in the aspen and maple-birch areas. The rate and compositional characteristics of succession in the ecotone relative to aspen and maple-birch forest types is presently under study

Converting partially-stocked aspen stands to fully-stocked stands in the Lake States: an economic analysis.

Science.gov (United States)

Jeffrey T. Olson; Allen L. Lundgren

1978-01-01

The 1968 Wisconsin Forest Survey showed large areas of aspen type that are not considered fully stocked. The economic feasibility of converting partially-stocked stands to full stocking is examined, and a rule presented for determining when a partially-stocked stand should be harvested to maximize its present value.

Mapping Tree Density in Forests of the Southwestern USA Using Landsat 8 Data

Directory of Open Access Journals (Sweden)

Kamal Humagain

2017-08-01

Full Text Available The increase of tree density in forests of the American Southwest promotes extreme fire events, understory biodiversity losses, and degraded habitat conditions for many wildlife species. To ameliorate these changes, managers and scientists have begun planning treatments aimed at reducing fuels and increasing understory biodiversity. However, spatial variability in tree density across the landscape is not well-characterized, and if better known, could greatly influence planning efforts. We used reflectance values from individual Landsat 8 bands (bands 2, 3, 4, 5, 6, and 7 and calculated vegetation indices (difference vegetation index, simple ratios, and normalized vegetation indices to estimate tree density in an area planned for treatment in the Jemez Mountains, New Mexico, characterized by multiple vegetation types and a complex topography. Because different vegetation types have different spectral signatures, we derived models with multiple predictor variables for each vegetation type, rather than using a single model for the entire project area, and compared the model-derived values to values collected from on-the-ground transects. Among conifer-dominated areas (73% of the project area, the best models (as determined by corrected Akaike Information Criteria (AICc included Landsat bands 2, 3, 4, and 7 along with simple ratios, normalized vegetation indices, and the difference vegetation index (R2 values for ponderosa: 0.47, piñon-juniper: 0.52, and spruce-fir: 0.66. On the other hand, in aspen-dominated areas (9% of the project area, the best model included individual bands 4 and 2, simple ratio, and normalized vegetation index (R2 value: 0.97. Most areas dominated by ponderosa, pinyon-juniper, or spruce-fir had more than 100 trees per hectare. About 54% of the study area has medium to high density of trees (100–1000 trees/hectare, and a small fraction (4.5% of the area has very high density (>1000 trees/hectare. Our results provide a

Recursive Trees for Practical ORAM

Directory of Open Access Journals (Sweden)

Moataz Tarik

2015-06-01

Full Text Available We present a new, general data structure that reduces the communication cost of recent tree-based ORAMs. Contrary to ORAM trees with constant height and path lengths, our new construction r-ORAM allows for trees with varying shorter path length. Accessing an element in the ORAM tree results in different communication costs depending on the location of the element. The main idea behind r-ORAM is a recursive ORAM tree structure, where nodes in the tree are roots of other trees. While this approach results in a worst-case access cost (tree height at most as any recent tree-based ORAM, we show that the average cost saving is around 35% for recent binary tree ORAMs. Besides reducing communication cost, r-ORAM also reduces storage overhead on the server by 4% to 20% depending on the ORAM’s client memory type. To prove r-ORAM’s soundness, we conduct a detailed overflow analysis. r-ORAM’s recursive approach is general in that it can be applied to all recent tree ORAMs, both constant and poly-log client memory ORAMs. Finally, we implement and benchmark r-ORAM in a practical setting to back up our theoretical claims.

Maintaining ecosystem resilience: functional responses of tree cavity nesters to logging in temperate forests of the Americas.

Science.gov (United States)

Ibarra, José Tomás; Martin, Michaela; Cockle, Kristina L; Martin, Kathy

2017-06-30

Logging often reduces taxonomic diversity in forest communities, but little is known about how this biodiversity loss affects the resilience of ecosystem functions. We examined how partial logging and clearcutting of temperate forests influenced functional diversity of birds that nest in tree cavities. We used point-counts in a before-after-control-impact design to examine the effects of logging on the value, range, and density of functional traits in bird communities in Canada (21 species) and Chile (16 species). Clearcutting, but not partial logging, reduced diversity in both systems. The effect was much more pronounced in Chile, where logging operations removed critical nesting resources (large decaying trees), than in Canada, where decaying aspen Populus tremuloides were retained on site. In Chile, logging was accompanied by declines in species richness, functional richness (amount of functional niche occupied by species), community-weighted body mass (average mass, weighted by species densities), and functional divergence (degree of maximization of divergence in occupied functional niche). In Canada, clearcutting did not affect species richness but nevertheless reduced functional richness and community-weighted body mass. Although some cavity-nesting birds can persist under intensive logging operations, their ecosystem functions may be severely compromised unless future nest trees can be retained on logged sites.

Portraits of Non-Tree Families

NARCIS (Netherlands)

Balgooy, van M.M.J.

2001-01-01

This is the third and final volume of the series ‘Malesian Seed Plants’. It contains the ‘portraits’ of 124 non-tree families, i.e. families which are mainly herbaceous, climbing, shrubby, or trees with a stem diameter at breast height of less than 10 cm or a height of less than 10 m. Users of the

ASPEN-AND-ESPEN: A postacute-care comparison of the basic definition of malnutrition from the American Society of Parenteral and Enteral Nutrition and Academy of Nutrition and Dietetics with the European Society for Clinical Nutrition and Metabolism definition.

Science.gov (United States)

Sánchez-Rodríguez, Dolores; Marco, Ester; Ronquillo-Moreno, Natalia; Maciel-Bravo, Liev; Gonzales-Carhuancho, Abel; Duran, Xavier; Guillén-Solà, Anna; Vázquez-Ibar, Olga; Escalada, Ferran; Muniesa, Josep M

2018-01-25

The aim of this study was to assess the prevalence of malnutrition by applying the ASPEN/AND definition and the ESPEN consensus definition in a postacute-care population, and secondly, to determine the metrological properties of the set of six clinical characteristics that constitute the ASPEN/AND basic diagnosis, compared to the ESPEN consensus, based mostly on objective anthropometric measurements. Prospective study of 84 consecutive deconditioned older inpatients (85.4 ± 6.2; 59.5% women) admitted for rehabilitation in postacute care. ASPEN/AND diagnosis of malnutrition was considered in presence of at least two of the following: low energy intake, fluid accumulation, diminished handgrip strength, and loss of weight, muscle mass, or subcutaneous fat. Sensitivity, specificity, positive and negative predictive values, accuracy, likelihood ratios, and kappa statistics were calculated for ASPEN/AND criteria and compared with ESPEN consensus. The prevalence of malnutrition by ASPEN/AND criteria was 63.1% and by ESPEN consensus, 20.2%; both diagnoses were associated with significantly longer length of stay, but the ESPEN definition was significantly associated with poorer functional outcomes after the rehabilitation program. Compared to ESPEN consensus, ASPEN/AND diagnosis showed fair validity (sensitivity = 94.1%; specificity = 44.8%); kappa statistic was 2.217. Applying the ASPEN/AND definition obtained a higher prevalence of malnutrition in a postacute-care population than was identified by the ESPEN definition. ASPEN/AND criteria had fair validity and agreement compared with the ESPEN definition. A simple, evidence-based, unified malnutrition definition might improve geriatric care. Copyright © 2018 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Nonbinary Tree-Based Phylogenetic Networks.

Science.gov (United States)

Jetten, Laura; van Iersel, Leo

2018-01-01

Rooted phylogenetic networks are used to describe evolutionary histories that contain non-treelike evolutionary events such as hybridization and horizontal gene transfer. In some cases, such histories can be described by a phylogenetic base-tree with additional linking arcs, which can, for example, represent gene transfer events. Such phylogenetic networks are called tree-based. Here, we consider two possible generalizations of this concept to nonbinary networks, which we call tree-based and strictly-tree-based nonbinary phylogenetic networks. We give simple graph-theoretic characterizations of tree-based and strictly-tree-based nonbinary phylogenetic networks. Moreover, we show for each of these two classes that it can be decided in polynomial time whether a given network is contained in the class. Our approach also provides a new view on tree-based binary phylogenetic networks. Finally, we discuss two examples of nonbinary phylogenetic networks in biology and show how our results can be applied to them.

Why do trees die? Characterizing the drivers of background tree mortality

Science.gov (United States)

Das, Adrian J.; Stephenson, Nathan L.; Davis, Kristin P.

2016-01-01

one another. Finally, beyond the current emphasis on folivory and leaf defenses, studies of broad-scale gradients in the nature and strength of biotic interactions should also include biotic attacks on, and defenses of, tree stems and roots.

Estimation of Physical Properties for Hydrogen Isotopes Using Aspen Plus Simulator

International Nuclear Information System (INIS)

Cho, Jung Ho; Yun, Sei Hun; Cho, Seung Yon; Chang, Min Ho; Kang, Hyun Goo; Jung, Ki Jung; Kim, Dong Min

2009-01-01

Hydrogen isotopes are H 2 , HD, D 2 , H 2 , HD, D 2 , HT, DT and T 2 . Among the hydrogen isotopes, the physical properties of H2, HD and D+2 are included in the Aspen Plus, however HT, D T and T 2 are not included. In this study, various thermodynamic properties were estimated for six components of isotopes by use of the fixed properties and temperature-dependent properties. To estimate thermodynamic properties, Soave modified Redlich-Kwong equation of state and Aspenplus simulator was used. The results were verified and compared with by PRO/II with PROVISION of Invensys

Mechanistic simulation of batch acetone-butanol-ethanol (ABE) fermentation with in situ gas stripping using Aspen Plus™.

Science.gov (United States)

Darkwah, Kwabena; Nokes, Sue E; Seay, Jeffrey R; Knutson, Barbara L

2018-05-22

Process simulations of batch fermentations with in situ product separation traditionally decouple these interdependent steps by simulating a separate "steady state" continuous fermentation and separation units. In this study, an integrated batch fermentation and separation process was simulated for a model system of acetone-butanol-ethanol (ABE) fermentation with in situ gas stripping, such that the fermentation kinetics are linked in real-time to the gas stripping process. A time-dependent cell growth, substrate utilization, and product production is translated to an Aspen Plus batch reactor. This approach capitalizes on the phase equilibria calculations of Aspen Plus to predict the effect of stripping on the ABE fermentation kinetics. The product profiles of the integrated fermentation and separation are shown to be sensitive to gas flow rate, unlike separate steady state fermentation and separation simulations. This study demonstrates the importance of coupled fermentation and separation simulation approaches for the systematic analyses of unsteady state processes.

Growth

Science.gov (United States)

John R. Jones; George A. Schier

1985-01-01

This chapter considers aspen growth as a process, and discusses some characteristics of the growth and development of trees and stands. For the most part, factors affecting growth are discussed elsewhere, particularly in the GENETICS AND VARIATION chapter and in chapters in PART 11. ECOLOGY. Aspen growth as it relates to wood production is examined in the WOOD RESOURCE...

A coinductive calculus of binary trees

NARCIS (Netherlands)

A.M. Silva (Alexandra); J.J.M.M. Rutten (Jan)

2007-01-01

htmlabstractWe study the set T_A of infinite binary trees with nodes labelled in a semiring A from a coalgebraic perspective. We present coinductive definition and proof principles based on the fact that T_A carries a final coalgebra structure. By viewing trees as formal power series, we develop a

Analyzing tree cores to detect petroleum hydrocarbon-contaminated groundwater at a former landfill site in the community of Happy Valley-Goose Bay, eastern Canadian subarctic.

Science.gov (United States)

Fonkwe, Merline L D; Trapp, Stefan

2016-08-01

This research examines the feasibility of analyzing tree cores to detect benzene, toluene, ethylbenzene, and m, p, o-xylene (BTEX) compounds and methyl tertiary-butyl ether (MTBE) in groundwater in eastern Canada subarctic environments, using a former landfill site in the remote community of Happy Valley-Goose Bay, Labrador. Petroleum hydrocarbon contamination at the landfill site is the result of environmentally unsound pre-1990s disposal of households and industrial solid wastes. Tree cores were taken from trembling aspen, black spruce, and white birch and analyzed by headspace-gas chromatography-mass spectrometry. BTEX compounds were detected in tree cores, corroborating known groundwater contamination. A zone of anomalously high concentrations of total BTEX constituents was identified and recommended for monitoring by groundwater wells. Tree cores collected outside the landfill site at a local control area suggest the migration of contaminants off-site. Tree species exhibit different concentrations of BTEX constituents, indicating selective uptake and accumulation. Toluene in wood exhibited the highest concentrations, which may also be due to endogenous production. Meanwhile, MTBE was not found in the tree cores and is considered to be absent in the groundwater. The results demonstrate that tree-core analysis can be useful for detecting anomalous concentrations of petroleum hydrocarbons, such as BTEX compounds, in subarctic sites with shallow unconfined aquifers and permeable soils. This method can therefore aid in the proper management of contamination during landfill operations and after site closures.

Response of a forest ecotone to ionizing radiation. Progress report, October 15, 1978-October 14, 1979

International Nuclear Information System (INIS)

Murphy, P.G.; Sharitz, R.R.

1979-07-01

Compositional and structural characteristics of three forest types, including aspen dominated, maple-birch dominated, and an intervening ecotone, were studied before and after irradiation in northern Wisconsin. Irradiation occurred during the summer of 1972. As of the summer of 1978, establishment of tree seedlings at 10 m from the radiation source continued to be inhibited by the vigorous development of ground vegetation except, in part, in the aspen area where seedling density increased sharply relative to 1977 because of an influx of Acer rubrum. By 1974 many of the seedlings at 20 m had reached the sapling size-class. At the present time it appears that recolonization of the 10 m irradiated zone by the original tree flora will be a very slow process, largely because of a dense growth of Rubus sp. and other heliophytes. As of 1978 the recovery of leaf litter production appeared to be continuing in all three areas although the ratios of tree to shrub litter were still well below preirradiation levels at 10 m and slightly below at 20 m. In most respects, the ecotone has shown properties and responses to radiation intermediate to those observed in the aspen and maple-birch areas. The rate and compositional characteristics of succession in the ecotone relative to aspen and maple-birch forest types is presently under study

Response of a forest ecotone to ionizing radiation. Progress report, April 15, 1983-April 14, 1984

International Nuclear Information System (INIS)

Murphy, P.G.; Sharitz, R.R.

1983-11-01

Compositional and structural characteristics of three forest types, including aspen dominated, maple-birch dominated, and an intervening ecotone (midecotone), were studied before and after irradiation in northern Wisconsin. In all three areas, the density of seedlings at 10 m was greatly reduced within a year following the 1972 radiation event. In the maple-birch area seedlings were virtually absent at 10 m until 1982 and 1983 when their numbers were comparable to preirradiation levels. In the aspen and midecotone areas 1983 seedling densities at 10 m were only 50 and 17%, respectively, of the preirradiation levels. Woody plants of tree stature were eliminated at 10 m in all three areas within two years of irradiation but by 1982 only the aspen area lacked plants in this size class. In 1982 total leaf litter production was 26 and 63% below 1971 preirradiation levels at 10 m in the aspen and maple-birch areas, respectively. But at 10 m in the midecotone, it had increased, relative to 1971, by 27%. The ratio of shrub to tree leaf litter continues to decline as the heavily irradiated zone of all three areas continues to be recolonized by tree species and the canopy at 20 m continues to fill out. Present studeis emphasize the rate at which the three areas continue to be recolonized, and the composition of the recolonizing flora, relative to the preirradiation forest

Soil Organic Carbon Storage and Stability in the Aspen-Conifer Ecotone in Montane Forests in Utah, USA

Directory of Open Access Journals (Sweden)

Mercedes Román Dobarco

2014-04-01

Full Text Available To assess the potential impact of conifer encroachment on soil organic carbon (SOC dynamics and storage in montane aspen-conifer forests from the interior western US, we sampled mineral soils (0–15 cm across the aspen-conifer ecotones in southern and northern Utah and quantified total SOC stocks, stable SOC (i.e., mineral-associated SOC (MoM, labile SOC (i.e., light fraction (LF, decomposable (CO2 release during long-term aerobic incubations and soluble SOC (hot water extractable organic carbon (HWEOC. Total SOC storage (47.0 ± 16.5 Mg C ha−1 and labile SOC as LF (14.0 ± 7.10 Mg C ha−1, SOC decomposability (cumulative released CO2-C of 5.6 ± 3.8 g C g−1 soil or HWEOC (0.6 ± 0.6 mg C g−1 soil did not differ substantially with vegetation type, although a slight increase in HWEOC was observed with increasing conifer in the overstory. There were statistically significant differences (p = 0.035 in stable MoM storage, which was higher under aspen (31.2 ± 15.1 Mg C ha−1 than under conifer (22.8 ± 9.0 Mg C ha−1, with intermediate values under mixed (25.7 ± 8.8 Mg C ha−1. Texture had the greatest impact on SOC distribution among labile and stable fractions, with increasing stabilization in MoM and decreasing bio-availability of SOC with increasing silt + clay content. Only at lower silt + clay contents (40%–70% could we discern the influence of vegetation on MoM content. This highlights the importance of chemical protection mechanisms for long-term C sequestration.

Downregulation of RWA genes in hybrid aspen affects xylan acetylation and wood saccharification.

Science.gov (United States)

Pawar, Prashant Mohan-Anupama; Ratke, Christine; Balasubramanian, Vimal K; Chong, Sun-Li; Gandla, Madhavi Latha; Adriasola, Mathilda; Sparrman, Tobias; Hedenström, Mattias; Szwaj, Klaudia; Derba-Maceluch, Marta; Gaertner, Cyril; Mouille, Gregory; Ezcurra, Ines; Tenkanen, Maija; Jönsson, Leif J; Mellerowicz, Ewa J

2017-06-01

High acetylation of angiosperm wood hinders its conversion to sugars by glycoside hydrolases, subsequent ethanol fermentation and (hence) its use for biofuel production. We studied the REDUCED WALL ACETYLATION (RWA) gene family of the hardwood model Populus to evaluate its potential for improving saccharification. The family has two clades, AB and CD, containing two genes each. All four genes are expressed in developing wood but only RWA-A and -B are activated by master switches of the secondary cell wall PtNST1 and PtMYB21. Histochemical analysis of promoter::GUS lines in hybrid aspen (Populus tremula × tremuloides) showed activation of RWA-A and -B promoters in the secondary wall formation zone, while RWA-C and -D promoter activity was diffuse. Ectopic downregulation of either clade reduced wood xylan and xyloglucan acetylation. Suppressing both clades simultaneously using the wood-specific promoter reduced wood acetylation by 25% and decreased acetylation at position 2 of Xylp in the dimethyl sulfoxide-extracted xylan. This did not affect plant growth but decreased xylose and increased glucose contents in the noncellulosic monosaccharide fraction, and increased glucose and xylose yields of wood enzymatic hydrolysis without pretreatment. Both RWA clades regulate wood xylan acetylation in aspen and are promising targets to improve wood saccharification. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Simulation of the gasification of animal wastes in a dual gasifier using Aspen Plus®

International Nuclear Information System (INIS)

Fernandez-Lopez, M.; Pedroche, J.; Valverde, J.L.; Sanchez-Silva, L.

2017-01-01

Highlights: • The gasification of manure was evaluated using the software Aspen Plus®. • Composition and LHV of the obtained syngas depends on the operating conditions. • CO 2 net emissions for the steam and CO 2 gasification processes were calculated. • Manure steam gasification can be used as feedstock for Fischer-Tropsch. • Manure CO 2 gasification lead to a syngas suitable for energy production. - Abstract: The gasification of an animal waste biomass (manure) in a dual gasifier was studied using the software Aspen Plus®. For this purpose, a model based on a Gibbs free energy reactor was considered. Effects of the gasification temperature, the gasifying/biomass ratio and the use of steam and CO 2 as the gasifying agents on the composition and the low heating value (LHV) of the produced syngas were evaluated. In this sense, the H 2 /CO ratio and the LHV were the parameters calculated to stablish the best operating conditions for the production of either hydrocarbons via Fischer-Tropsch or energy. Furthermore, the CO 2 net emissions generated by the gasification process were also important in the selection of the best operating conditions from an environmental point of view. The obtained results showed that for both gasifying agents the H 2 and CO production was favoured at high temperatures whereas the production of CH 4 and CO 2 was favoured at low ones. On the other hand, the H 2 production was higher when steam was used as the gasifying agent and the formation of CO was enhanced when CO 2 was considered as gasification agent. An increase of the gasifying agent/biomass ratio had a negatively influence on the production of CH 4 , leading to a decrease of the LHV. Therefore, steam as the gasifying agent and high temperatures favoured the obtaining of a syngas suitable for the Fischer-Tropsch process whereas CO 2 and low gasification temperatures enhanced a syngas with a high LHV which could be used for energy production. Finally, the net CO 2

Simulación y validación de modelos de destilación por lotes usando Aspen Batch Modeler: recuperación de epóxido de limoneno

OpenAIRE

Yeison Agudelo; Rolando Barrera Zapata

2016-01-01

Se desarrolló el modelado y simulación de una columna de destilación por lotes para la recuperación de epóxido de limoneno de una mezcla multicomponente, usando el software especializado Aspen Batch Modeler. Para la validación de los modelos se desarrolló el proceso experimental en un equipo de roto-evaporación, donde se varió la composición inicial de la mezcla, temperatura y presión de operación. La composición final de fondos y destilado se determinó a través de cromatografía de gases. Los...

Orbital Express Mission Operations Planning and Resource Management using ASPEN

Science.gov (United States)

Chouinard, Caroline; Knight, Russell; Jones, Grailing; Tran, Danny

2008-01-01

The Orbital Express satellite servicing demonstrator program is a DARPA program aimed at developing "a safe and cost-effective approach to autonomously service satellites in orbit". The system consists of: a) the Autonomous Space Transport Robotic Operations (ASTRO) vehicle, under development by Boeing Integrated Defense Systems, and b) a prototype modular next-generation serviceable satellite, NEXTSat, being developed by Ball Aerospace. Flexibility of ASPEN: a) Accommodate changes to procedures; b) Accommodate changes to daily losses and gains; c) Responsive re-planning; and d) Critical to success of mission planning Auto-Generation of activity models: a) Created plans quickly; b) Repetition/Re-use of models each day; and c) Guarantees the AML syntax. One SRP per day vs. Tactical team

Thermal analysis of wood of the main tree species of Central Siberia

Directory of Open Access Journals (Sweden)

S. R. Loskutov

2015-12-01

Full Text Available Thermal decomposition of wood from coniferous and deciduous species of Siberia has been studied using thermogravimetry (TG and differential scanning calorimetry (DSC. The tree species were larch Larix sibirica Ledeb., Scots pine Pinus sylvestris L., spruce Picea obovata Ledeb., fir Abies sibirica Ledeb., Siberian pine Pinus sibirica Du Tour., birch Betula pendula Roth., and aspen Populus tremula L. Thermal analysis of wood samples was carried out under oxidative (air and inert (argon atmospheres from 25 to 700 °С at heating rates 10, 20, 40 °С • min–1 (TG/DTG and from 25 to 590 °С at heating rates 10, 40 °С • min–1 (DSC. The stages of thermal decomposition, the temperature intervals, the mass loss, the mass loss rate, the temperature of DTG/DSC peaks, and heating effects were determined for each tree species. The kinetic thermal degradation parameters of wood were obtained by the Broido and Ozawa–Flynn–Wall models. The wood of coniferous and deciduous species of Siberia was characterized on the base of analysis of activation energy values at various stages of thermal decomposition and the relations of activation energy on conversion level of wood substance of different tree species, and also the comparison of mass loss at the same stages of thermal destruction, heating effects, residual mass and other parameters of TG/DTG, DSC. In our opinion, the results of this work present interest for researchers and specialists in the field of forest pyrology, wood science, dendrochemistry.

Market-based approaches to tree valuation

Science.gov (United States)

Geoffrey H. Donovan; David T. Butry

2008-01-01

A recent four-part series in Arborist News outlined different appraisal processes used to value urban trees. The final article in the series described the three generally accepted approaches to tree valuation: the sales comparison approach, the cost approach, and the income capitalization approach. The author, D. Logan Nelson, noted that the sales comparison approach...

A system for predicting the amount of Phellinus (Fomes) igniarius rot in trembling aspen stands

Science.gov (United States)

Robert L. Anderson; Arthur L. Jr. Schipper

1978-01-01

The occurrence of Phellinus (Fomes) igniarius white trunk rot in 45- to 50-year-old trembling aspen stands can be predicted by applying a constant to the stand basal area with P. igniarius conks to estimate the total basal area with P. igniarius rot. Future decay projections can be made by reapplying the basal area of hidden decay for each 6 years projected. This paper...

Decision tree modeling using R.

Science.gov (United States)

Zhang, Zhongheng

2016-08-01

In machine learning field, decision tree learner is powerful and easy to interpret. It employs recursive binary partitioning algorithm that splits the sample in partitioning variable with the strongest association with the response variable. The process continues until some stopping criteria are met. In the example I focus on conditional inference tree, which incorporates tree-structured regression models into conditional inference procedures. While growing a single tree is subject to small changes in the training data, random forests procedure is introduced to address this problem. The sources of diversity for random forests come from the random sampling and restricted set of input variables to be selected. Finally, I introduce R functions to perform model based recursive partitioning. This method incorporates recursive partitioning into conventional parametric model building.

Aspen Simulation of Diesel-Biodiesel Blends Combustion

Directory of Open Access Journals (Sweden)

Pérez-Sánchez Armando

2015-01-01

Full Text Available Biodiesel is a fuel produced by transesterification of vegetable oils or animal fats, which currently is gaining attention as a diesel substitute. It represents an opportunity to reduce CO2, SO2, CO, HC, PAH and PM emissions and contributes to the diversification of fuels in Mexico's energetic matrix. The results of the simulation of the combustion process are presented in this paper with reference to an engine specification KUBOTA D600-B, operated with diesel-biodiesel blends. The physicochemical properties of the compounds and the operating conditions of equipment were developed using the simulator Aspen® and supplementary information. The main aspects of the engine working conditions were considered such as diesel-biodiesel ratio, air/fuel mixture, temperature of the combustion gases and heat load. Diesel physicochemical specifications were taken from reports of PEMEX and SENER. Methyl esters corresponding to the transesterification of fatty acids that comprise castor oil were regarded as representative molecules of biodiesel obtained from chromatographic analysis. The results include CO2, water vapor, combustion efficiency, power and lower calorific value of fuels.

Wood-inhabiting, polyporoid fungi in aspen-dominated forests managed for biomass in the U.S. Lake States

Science.gov (United States)

Nicholas J. Brazee; Daniel L. Lindner; Shawn Fraver; Anthony W. D' Amato; Amy M. Milo

2012-01-01

To better understand the potential long-term effects of biomass harvesting on biodiversity, the polyporoid fungi community was characterized from 120 plots in four aspen-dominated forests in Minnesota. Four deadwood variables (substratum species, substratum type, decay class and diameter class) were recorded for each polyporoid species occurrence. A total of 2358...

The stopping rules for winsorized tree

Science.gov (United States)

Ch'ng, Chee Keong; Mahat, Nor Idayu

2017-11-01

Winsorized tree is a modified tree-based classifier that is able to investigate and to handle all outliers in all nodes along the process of constructing the tree. It overcomes the tedious process of constructing a classical tree where the splitting of branches and pruning go concurrently so that the constructed tree would not grow bushy. This mechanism is controlled by the proposed algorithm. In winsorized tree, data are screened for identifying outlier. If outlier is detected, the value is neutralized using winsorize approach. Both outlier identification and value neutralization are executed recursively in every node until predetermined stopping criterion is met. The aim of this paper is to search for significant stopping criterion to stop the tree from further splitting before overfitting. The result obtained from the conducted experiment on pima indian dataset proved that the node could produce the final successor nodes (leaves) when it has achieved the range of 70% in information gain.

Logging methods and peeling of Aspen

Science.gov (United States)

T. Schantz-Hansen

1948-01-01

The logging of forest products is influenced by many factors, including the size of the trees, density of the stand, the soundness of the trees, size of the area logged, topography and soil, weather conditions, the degree of utilization, the skill of the logger and the equipment used, the distance from market, etc. Each of these factors influences not only the method...

Accounting for density reduction and structural loss in standing dead trees: Implications for forest biomass and carbon stock estimates in the United States

Directory of Open Access Journals (Sweden)

Domke Grant M

2011-11-01

Full Text Available Abstract Background Standing dead trees are one component of forest ecosystem dead wood carbon (C pools, whose national stock is estimated by the U.S. as required by the United Nations Framework Convention on Climate Change. Historically, standing dead tree C has been estimated as a function of live tree growing stock volume in the U.S.'s National Greenhouse Gas Inventory. Initiated in 1998, the USDA Forest Service's Forest Inventory and Analysis program (responsible for compiling the Nation's forest C estimates began consistent nationwide sampling of standing dead trees, which may now supplant previous purely model-based approaches to standing dead biomass and C stock estimation. A substantial hurdle to estimating standing dead tree biomass and C attributes is that traditional estimation procedures are based on merchantability paradigms that may not reflect density reductions or structural loss due to decomposition common in standing dead trees. The goal of this study was to incorporate standing dead tree adjustments into the current estimation procedures and assess how biomass and C stocks change at multiple spatial scales. Results Accounting for decay and structural loss in standing dead trees significantly decreased tree- and plot-level C stock estimates (and subsequent C stocks by decay class and tree component. At a regional scale, incorporating adjustment factors decreased standing dead quaking aspen biomass estimates by almost 50 percent in the Lake States and Douglas-fir estimates by more than 36 percent in the Pacific Northwest. Conclusions Substantial overestimates of standing dead tree biomass and C stocks occur when one does not account for density reductions or structural loss. Forest inventory estimation procedures that are descended from merchantability standards may need to be revised toward a more holistic approach to determining standing dead tree biomass and C attributes (i.e., attributes of tree biomass outside of sawlog

Effects of elevated atmospheric CO2 and/or O3 on intra- and interspecific competitive ability of aspen

Science.gov (United States)

M. E. Kubiske; V. S. Quinn; P. E. Marquardt; D. F. Karnosky

2007-01-01

Three model communities of trembling aspen (monoculture, and mixed with either paper birch or sugar maple) were grown for seven years in elevated atmospheric CO2 and O3 using Free Air CO2 Enrichment (FACE) technology. We utilized trends in species' importance, calculated as an index of volume...

Mathematical foundations of event trees

International Nuclear Information System (INIS)

Papazoglou, Ioannis A.

1998-01-01

A mathematical foundation from first principles of event trees is presented. The main objective of this formulation is to offer a formal basis for developing automated computer assisted construction techniques for event trees. The mathematical theory of event trees is based on the correspondence between the paths of the tree and the elements of the outcome space of a joint event. The concept of a basic cylinder set is introduced to describe joint event outcomes conditional on specific outcomes of basic events or unconditional on the outcome of basic events. The concept of outcome space partition is used to describe the minimum amount of information intended to be preserved by the event tree representation. These concepts form the basis for an algorithm for systematic search for and generation of the most compact (reduced) form of an event tree consistent with the minimum amount of information the tree should preserve. This mathematical foundation allows for the development of techniques for automated generation of event trees corresponding to joint events which are formally described through other types of graphical models. Such a technique has been developed for complex systems described by functional blocks and it is reported elsewhere. On the quantification issue of event trees, a formal definition of a probability space corresponding to the event tree outcomes is provided. Finally, a short discussion is offered on the relationship of the presented mathematical theory with the more general use of event trees in reliability analysis of dynamic systems

Effects of elevated CO2 leaf diets on gypsy moth (Lepidoptera: Lymantriidae) respiration rates.

Science.gov (United States)

Foss, Anita R; Mattson, William J; Trier, Terry M

2013-06-01

Elevated levels of CO2 affect plant growth and leaf chemistry, which in turn can alter host plant suitability for insect herbivores. We examined the suitability of foliage from trees grown from seedlings since 1997 at Aspen FACE as diet for the gypsy moth (Lymantria dispar L.) Lepidoptera: Lymantriidae: paper birch (Betula papyrifera Marshall) in 2004-2005, and trembling aspen (Populus tremuloides Michaux) in 2006-2007, and measured consequent effects on larval respiration. Leaves were collected for diet and leaf chemistry (nutritional and secondary compound proxies) from trees grown under ambient (average 380 ppm) and elevated CO2 (average 560 ppm) conditions. Elevated CO2 did not significantly alter birch or aspen leaf chemistry compared with ambient levels with the exception that birch percent carbon in 2004 and aspen moisture content in 2006 were significantly lowered. Respiration rates were significantly higher (15-59%) for larvae reared on birch grown under elevated CO2 compared with ambient conditions, but were not different on two aspen clones, until larvae reached the fifth instar, when those consuming elevated CO2 leaves on clone 271 had lower (26%) respiration rates, and those consuming elevated CO2 leaves on clone 216 had higher (36%) respiration rates. However, elevated CO2 had no apparent effect on the respiration rates of pupae derived from larvae fed either birch or aspen leaves. Higher respiration rates for larvae fed diets grown under ambient or elevated CO2 demonstrates their lower efficiency of converting chemical energy of digested food stuffs extracted from such leaves into their biosynthetic processes.

Using aspen for artist stretcher frames: adding value through quality service, direct marketing, and careful material selection

Science.gov (United States)

Chris Polson

2001-01-01

Aspen wood, when carefully selected and kiln dried, makes excellent stock for artist stretcher frames. Direct marketing techniques including the Internet and word of mouth give access to national markets, providing a more diverse and stable customer base for operations from a rural area. High-quality service, as shown by product performance and rapid order fulfillment...

New perspectives on the ecology of tree structure and tree communities through terrestrial laser scanning.

Science.gov (United States)

Malhi, Yadvinder; Jackson, Tobias; Patrick Bentley, Lisa; Lau, Alvaro; Shenkin, Alexander; Herold, Martin; Calders, Kim; Bartholomeus, Harm; Disney, Mathias I

2018-04-06

Terrestrial laser scanning (TLS) opens up the possibility of describing the three-dimensional structures of trees in natural environments with unprecedented detail and accuracy. It is already being extensively applied to describe how ecosystem biomass and structure vary between sites, but can also facilitate major advances in developing and testing mechanistic theories of tree form and forest structure, thereby enabling us to understand why trees and forests have the biomass and three-dimensional structure they do. Here we focus on the ecological challenges and benefits of understanding tree form, and highlight some advances related to capturing and describing tree shape that are becoming possible with the advent of TLS. We present examples of ongoing work that applies, or could potentially apply, new TLS measurements to better understand the constraints on optimization of tree form. Theories of resource distribution networks, such as metabolic scaling theory, can be tested and further refined. TLS can also provide new approaches to the scaling of woody surface area and crown area, and thereby better quantify the metabolism of trees. Finally, we demonstrate how we can develop a more mechanistic understanding of the effects of avoidance of wind risk on tree form and maximum size. Over the next few years, TLS promises to deliver both major empirical and conceptual advances in the quantitative understanding of trees and tree-dominated ecosystems, leading to advances in understanding the ecology of why trees and ecosystems look and grow the way they do.

Flambeau Mining Corporation, Ladysmith, Rusk County, Wisconsin. Proposed Open Pit Copper Mine and Waste Containment Area, Draft Environmental Impact Statement.

Science.gov (United States)

1976-08-01

American elm Lonicera tatarica - tartarian honeysuckle Ulmus rubra - slippery elm Siiibucus canadenis - common elder Ulmus thoiii~sii - cork elm ...community borders the marshes and swamps. 2.060 The predominant species are the trembling aspen (Populus tremuloides), red maple (Acer rubrum), the elms ...succession. The most numerous trees (in descending order) are: white birch, red maple, aspen, sugar maple, black ash, basswood, elm (Ulmus sp.), hemlock

Semi-Interpenetrating polymer network hydrogels based on aspen hemicellulose and chitosan: Effect of crosslinking sequence on hydrogel properties

Science.gov (United States)

Muzaffer Ahmet Karaaslan; Mandla A. Tshabalala; Gisela Buschle-Diller

2012-01-01

Semi-interpenetrating network hydrogel films were prepared using hemicellulose and chemically crosslinked chitosan. Hemicellulose was extracted from aspen by using a novel alkaline treatment and characterized by HPSEC, and consisted of a mixture of high and low molecular weight polymeric fractions. HPLC analysis of the acid hydrolysate of the hemicellulose showed that...

Circadian patterns of xylem sap properties and their covariation with plant hydraulic traits in hybrid aspen.

Science.gov (United States)

Meitern, Annika; Õunapuu-Pikas, Eele; Sellin, Arne

2017-06-01

Physiological processes taking place in plants are subject to diverse circadian patterns but some of them are poorly documented in natural conditions. The daily dynamics of physico-chemical properties of xylem sap and their covariation with tree hydraulic traits were investigated in hybrid aspen (Populus tremula L.×P. tremuloides Michx) in field conditions in order to clarify which environmental drivers govern the daily variation in these parameters. K + concentration ([K + ]), electrical conductivity (σ sap ), osmolality (Osm) and pH of the xylem sap, as well as branch hydraulic traits, were measured in the field over 24-h cycles. All studied xylem sap properties and hydraulic characteristics including whole-branch (K wb ), leaf blade (K lb ) and petiole hydraulic conductances (K P ) showed clear daily dynamics. Air temperature (T A ) and photosynthetic photon flux density (PPFD), but also water vapour pressure deficit (VPD) and relative humidity (RH), had significant impacts on K wb K lb , K P , [K + ] and σ sap . Osm varied only with light intensity, while K B varied depending on atmospheric evaporative demand expressed as T A , VPD or RH. Xylem sap pH depended inversely on soil water potential (Ψ S ) and during daylight also on VPD. Although soil water content was close to saturation during the study period, Ψ S influenced also [K + ] and σ sap . The present study presents evidence of coupling between circadian patterns of xylem sap properties and plant hydraulic conductance providing adequate water supply to foliage under environmental conditions characterised by diurnal variation. Copyright © 2017 Elsevier GmbH. All rights reserved.

Software development to assist in fault tree construction

International Nuclear Information System (INIS)

Simic, Z.; Mikulicic, V.

1992-01-01

This paper reviews and classifies fault tree construction methods developed for system safety and reliability. We have outlined two generally different approaches: automatic and interactive fault tree construction. Automatic fault tree approach is no jet enough developed to covering various uses in practice. Interactive approach is intending to be support to the analyst (not vice verse like in automatic approach). The aim is not so high as automatic one but it is accessible. We have favored interactive approach as well because to our opinion the process of fault tree construction is very important for better system understanding. We have described our example of interactive fault tree construction approach. Computer code GIFFT (Graphical Interactive Fault Tree Tool) is in phase of intensive testing and final developing. (author) [hr

Response of a forest ecotone to ionizing radiation. Progress report, October 15, 1981-April 14, 1983

International Nuclear Information System (INIS)

Murphy, P.G.; Sharitz, R.R.

1982-11-01

Compositional and structural characteristics of three forest types, including aspen dominated, maple-birch dominated, and an intervening ecotone (midecotone), were studied before and after irradiation in northern Wisconsin. In all three areas, the density of seedlings at 10 m was greatly reduced within a year following the 1972 radiation event. Woody plants of tree stature were eliminated at 10 m in all three areas within two years of irradiation but by 1982 only the aspen area lacked plants in this size class. The low densities of young trees in the other two areas at 10 m were of successional species rather than the original species killed by radiation. In 1981 total leaf litter production was 42 and 61% below 1971 preirradiation levels at 10 m in the aspen and maple-birch areas, respectively. But at 10 m in the midecotone, it had increased, relative to 1971, by 23%. The ratio of shrub to tree leaf litter continues to decline as the heavily irradiated zone of all three areas continues to be recolonized by tree species and the canopy at 20 m continues to fill out. Our present studies emphasize the rate at which the three areas continue to be recolonized and the composition of the recolonizing flora, relative to the preirradiation forest. Influences of the successional shrub species within 10 m are of particular interest and are also under study

Pectin methyl esterase inhibits intrusive and symplastic cell growth in developing wood cells of Populus.

Science.gov (United States)

Siedlecka, Anna; Wiklund, Susanne; Péronne, Marie-Amélie; Micheli, Fabienne; Lesniewska, Joanna; Sethson, Ingmar; Edlund, Ulf; Richard, Luc; Sundberg, Björn; Mellerowicz, Ewa J

2008-02-01

Wood cells, unlike most other cells in plants, grow by a unique combination of intrusive and symplastic growth. Fibers grow in diameter by diffuse symplastic growth, but they elongate solely by intrusive apical growth penetrating the pectin-rich middle lamella that cements neighboring cells together. In contrast, vessel elements grow in diameter by a combination of intrusive and symplastic growth. We demonstrate that an abundant pectin methyl esterase (PME; EC 3.1.1.11) from wood-forming tissues of hybrid aspen (Populus tremula x tremuloides) acts as a negative regulator of both symplastic and intrusive growth of developing wood cells. When PttPME1 expression was up- and down-regulated in transgenic aspen trees, the PME activity in wood-forming tissues was correspondingly altered. PME removes methyl ester groups from homogalacturonan (HG) and transgenic trees had modified HG methylesterification patterns, as demonstrated by two-dimensional nuclear magnetic resonance and immunostaining using PAM1 and LM7 antibodies. In situ distributions of PAM1 and LM7 epitopes revealed changes in pectin methylesterification in transgenic trees that were specifically localized in expanding wood cells. The results show that en block deesterification of HG by PttPME1 inhibits both symplastic growth and intrusive growth. PttPME1 is therefore involved in mechanisms determining fiber width and length in the wood of aspen trees.

Decision trees in epidemiological research.

Science.gov (United States)

Venkatasubramaniam, Ashwini; Wolfson, Julian; Mitchell, Nathan; Barnes, Timothy; JaKa, Meghan; French, Simone

2017-01-01

In many studies, it is of interest to identify population subgroups that are relatively homogeneous with respect to an outcome. The nature of these subgroups can provide insight into effect mechanisms and suggest targets for tailored interventions. However, identifying relevant subgroups can be challenging with standard statistical methods. We review the literature on decision trees, a family of techniques for partitioning the population, on the basis of covariates, into distinct subgroups who share similar values of an outcome variable. We compare two decision tree methods, the popular Classification and Regression tree (CART) technique and the newer Conditional Inference tree (CTree) technique, assessing their performance in a simulation study and using data from the Box Lunch Study, a randomized controlled trial of a portion size intervention. Both CART and CTree identify homogeneous population subgroups and offer improved prediction accuracy relative to regression-based approaches when subgroups are truly present in the data. An important distinction between CART and CTree is that the latter uses a formal statistical hypothesis testing framework in building decision trees, which simplifies the process of identifying and interpreting the final tree model. We also introduce a novel way to visualize the subgroups defined by decision trees. Our novel graphical visualization provides a more scientifically meaningful characterization of the subgroups identified by decision trees. Decision trees are a useful tool for identifying homogeneous subgroups defined by combinations of individual characteristics. While all decision tree techniques generate subgroups, we advocate the use of the newer CTree technique due to its simplicity and ease of interpretation.

Sustainable cultivation of broadleaved trees in a recycling community

International Nuclear Information System (INIS)

Christersson, L.

1996-01-01

In the future, with problems of global warming and acidification and with an increasing need to recirculate wastes of the community in an ecologically acceptable and economically sound manner, the cultivation of broadleaved species (birch, aspen, poplar, alder and willow in particular) on suitable forest land and on former agricultural land is of utmost interest if following the recycling philosophy. The wood produced could be used primarily for short fibres and for energy. Also of interest is the production of methanol, biogas and electricity, chipboard and laminates, in the context of a forest industry concerned with the further development of the raw materials. The main advantages of cultivating fast-growing, broadleaved trees on former agricultural land are that: * in Sweden it has been shown possible to produce 10-12 tonnes of dry matter of woody biomass per hectare and year by cultivating willows and hybrid poplars, * in such plantations, the energy efficiency ratio will be 1 to 15-20, meaning that for every energy unit used, 15-20 can be harvested, and * some residual products from society, such as sludges, ashes, and wastewaters can be used as fertilizers in such plantations. 16 refs

Steiner trees for fixed orientation metrics

DEFF Research Database (Denmark)

Brazil, Marcus; Zachariasen, Martin

2009-01-01

We consider the problem of constructing Steiner minimum trees for a metric defined by a polygonal unit circle (corresponding to s = 2 weighted legal orientations in the plane). A linear-time algorithm to enumerate all angle configurations for degree three Steiner points is given. We provide...... a simple proof that the angle configuration for a Steiner point extends to all Steiner points in a full Steiner minimum tree, such that at most six orientations suffice for edges in a full Steiner minimum tree. We show that the concept of canonical forms originally introduced for the uniform orientation...... metric generalises to the fixed orientation metric. Finally, we give an O(s n) time algorithm to compute a Steiner minimum tree for a given full Steiner topology with n terminal leaves....

Simulation of SOFCs based power generation system using Aspen

Directory of Open Access Journals (Sweden)

Pianko-Oprych Paulina

2017-12-01

Full Text Available This study presents a thermodynamic Aspen simulation model for Solid Oxide Fuel Cells, SOFCs, based power generation system. In the first step, a steady-state SOFCs system model was developed. The model includes the electrochemistry and the diffusion phenomena. The electrochemical model gives good agreement with experimental data in a wide operating range. Then, a parametric study has been conducted to estimate effects of the oxygen to carbon ratio, O/C, on reformer temperature, fuel cell temperature, fuel utilization, overall fuel cell performance, and the results are discussed in this paper. In the second step, a dynamic analysis of SOFCs characteristic has been developed. The aim of dynamic modelling was to find the response of the system against the fuel utilization and the O/C ratio variations. From the simulations, it was concluded that both developed models in the steady and dynamic state were reasonably accurate and can be used for system level optimization studies of the SOFC based power generation system.

Elevated [CO2] magnifies isoprene emissions under heat and improves thermal resistance in hybrid aspen

OpenAIRE

Sun, Zhihong; H?ve, Katja; Vislap, Vivian; Niinemets, ?lo

2013-01-01

Isoprene emissions importantly protect plants from heat stress, but the emissions become inhibited by instantaneous increase of [CO2], and it is currently unclear how isoprene-emitting plants cope with future more frequent and severe heat episodes under high [CO2]. Hybrid aspen (Populus tremula x Populus tremuloides) saplings grown under ambient [CO2] of 380 ?mol mol?1 and elevated [CO2] of 780 ?mol mol?1 were used to test the hypothesis that acclimation to elevated [CO2] reduces the inhibito...

Simulation and validation of chemical-looping combustion using ASPEN plus

Energy Technology Data Exchange (ETDEWEB)

Zhou, Ling [Research Center of Fluid Machinery Engineering and Technology, Jiangsu University, Zhenjiang 212013 (China); Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States); Zhang, Zheming; Agarwal, Ramesh K. [Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130 (United States)

2013-07-01

Laboratory-scale experimental studies have demonstrated that Chemical-Looping Combustion (CLC) is an advanced technology which holds great potential for high-efficiency low-cost carbon capture. The generated syngas in CLC is subsequently oxidized to CO2 and H2O by reaction with an oxygen carrier. In this paper, process-level models of CLC are established in ASPEN Plus code for detailed simulations. The entire CLC process, from the beginning of coal gasification to reduction and oxidation of the oxygen carrier is modeled. The heat content of each major component such as fuel and air reactors and air/flue gas heat exchangers is carefully examined. Large amount of energy is produced in the fuel reactor, but energy needs to be supplied to the air reactor. The overall performance and efficiency of the modeled CLC systems are also evaluated.

Date palm waste gasification in downdraft gasifier and simulation using ASPEN HYSYS

International Nuclear Information System (INIS)

Bassyouni, M.; Waheed ul Hasan, Syed; Abdel-Aziz, M.H.; Abdel-hamid, S.M.-S.; Naveed, Shahid; Hussain, Ahmed; Ani, Farid Nasir

2014-01-01

Highlights: • Simulation of date palm waste gasification using ASPEN HYSYS was studied. • A steady state simulation of downdraft gasifier has been developed. • The results were used to predict synthesis gas composition. • Simulation results and experimental results are in good agreement. - Abstract: The present research aims to study the simulation of date palm waste gasification using ASPEN HYSYS. A steady state simulation of downdraft gasifier firing date palm leaves has been developed. The model is able to predict syngas composition with sound accuracy and can be used to find optimal operating conditions of the gasifier. Biomass is defined as an unconventional hypothetical solid component in HYSYS. A set of six reactor models simulates various reaction zones of the downdraft gasifier in accordance with its hydrodynamics. Biomass decomposition into constituents in the pyrolysis zone is modeled with a conversion reactor. The combustion of char and volatiles in the combustion zone are modeled with equilibrium and Gibbs reactor models respectively. The gasification zone is modeled with a Gibbs and equilibrium reactor. The results of simulation are validated against experimental results of a parametric variability study on a lab scale gasifier. The proportion of synthesis gas increase as temperature increases (concentration, molar fraction, and partial pressure). CO 2 and CH 4 in the product gases were also found to decrease with increasing temperature. At 800 °C, the exit gas reaches a stable molar composition (H 2 = 56.27%, CO = 21.71%, CO 2 = 18.24%, CH 4 = 3.78%). Increasing steam to biomass ratio increases CO 2 and H 2 at the expense of CO, governed by shift reaction. Steam induction increases the methane contents, thereby improves the heating value of the product gas

Date palm waste gasification in downdraft gasifier and simulation using ASPEN HYSYS

Energy Technology Data Exchange (ETDEWEB)

Bassyouni, M. [Department of Chemical and Materials Engineering, King Abdulaziz University, Rabigh 21911 (Saudi Arabia); Department of Chemical Engineering, Higher Technological Institute, Tenth of Ramdan City (Egypt); Waheed ul Hasan, Syed [Department of Chemical and Materials Engineering, King Abdulaziz University, Rabigh 21911 (Saudi Arabia); Abdel-Aziz, M.H., E-mail: helmy2002@gmail.com [Department of Chemical and Materials Engineering, King Abdulaziz University, Rabigh 21911 (Saudi Arabia); Chemical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria (Egypt); Abdel-hamid, S. M.-S. [Department of Chemical Engineering, Higher Technological Institute, Tenth of Ramdan City (Egypt); Naveed, Shahid [Punjab Institute of Contemporary Sciences, 5.5 KM Raiwind Road, Lahore (Pakistan); Hussain, Ahmed [Department of Nuclear Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Ani, Farid Nasir [Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, UTM 81310 Johor Bahru (Malaysia)

2014-12-15

Highlights: • Simulation of date palm waste gasification using ASPEN HYSYS was studied. • A steady state simulation of downdraft gasifier has been developed. • The results were used to predict synthesis gas composition. • Simulation results and experimental results are in good agreement. - Abstract: The present research aims to study the simulation of date palm waste gasification using ASPEN HYSYS. A steady state simulation of downdraft gasifier firing date palm leaves has been developed. The model is able to predict syngas composition with sound accuracy and can be used to find optimal operating conditions of the gasifier. Biomass is defined as an unconventional hypothetical solid component in HYSYS. A set of six reactor models simulates various reaction zones of the downdraft gasifier in accordance with its hydrodynamics. Biomass decomposition into constituents in the pyrolysis zone is modeled with a conversion reactor. The combustion of char and volatiles in the combustion zone are modeled with equilibrium and Gibbs reactor models respectively. The gasification zone is modeled with a Gibbs and equilibrium reactor. The results of simulation are validated against experimental results of a parametric variability study on a lab scale gasifier. The proportion of synthesis gas increase as temperature increases (concentration, molar fraction, and partial pressure). CO{sub 2} and CH{sub 4} in the product gases were also found to decrease with increasing temperature. At 800 °C, the exit gas reaches a stable molar composition (H{sub 2} = 56.27%, CO = 21.71%, CO{sub 2} = 18.24%, CH{sub 4} = 3.78%). Increasing steam to biomass ratio increases CO{sub 2} and H{sub 2} at the expense of CO, governed by shift reaction. Steam induction increases the methane contents, thereby improves the heating value of the product gas.

Decision trees in epidemiological research

Directory of Open Access Journals (Sweden)

Ashwini Venkatasubramaniam

2017-09-01

Full Text Available Abstract Background In many studies, it is of interest to identify population subgroups that are relatively homogeneous with respect to an outcome. The nature of these subgroups can provide insight into effect mechanisms and suggest targets for tailored interventions. However, identifying relevant subgroups can be challenging with standard statistical methods. Main text We review the literature on decision trees, a family of techniques for partitioning the population, on the basis of covariates, into distinct subgroups who share similar values of an outcome variable. We compare two decision tree methods, the popular Classification and Regression tree (CART technique and the newer Conditional Inference tree (CTree technique, assessing their performance in a simulation study and using data from the Box Lunch Study, a randomized controlled trial of a portion size intervention. Both CART and CTree identify homogeneous population subgroups and offer improved prediction accuracy relative to regression-based approaches when subgroups are truly present in the data. An important distinction between CART and CTree is that the latter uses a formal statistical hypothesis testing framework in building decision trees, which simplifies the process of identifying and interpreting the final tree model. We also introduce a novel way to visualize the subgroups defined by decision trees. Our novel graphical visualization provides a more scientifically meaningful characterization of the subgroups identified by decision trees. Conclusions Decision trees are a useful tool for identifying homogeneous subgroups defined by combinations of individual characteristics. While all decision tree techniques generate subgroups, we advocate the use of the newer CTree technique due to its simplicity and ease of interpretation.

Simulation of Synthesis Gas Production from Steam Oxygen Gasification of Colombian Coal Using Aspen Plus®

Directory of Open Access Journals (Sweden)

Jorge E. Preciado

2012-11-01

Full Text Available A steady state simulation of syngas production from a Steam Oxygen Gasification process using commercial technologies was performed using Aspen Plus®. For the simulation, the average proximate and ultimate compositions of bituminous coal obtained from the Colombian Andean region were employed. The simulation was applied to conduct sensitivity analyses in the O2 to coal mass ratio, coal slurry concentration, WGS operating temperature and WGS steam to dry gas molar ratio (SDG over the key parameters: syngas molar composition, overall CO conversion in the WGS reactors, H2 rich-syngas lower heating value (LHV and thermal efficiency. The achieved information allows the selection of critical operating conditions leading to improve system efficiency and environmental performance. The results indicate that the oxygen to carbon ratio is a key variable as it affects significantly both the LHV and thermal efficiency. Nevertheless, the process becomes almost insensitive to SDG values higher than 2. Finally, a thermal efficiency of 62.6% can be reached. This result corresponds to a slurry solid concentration of 0.65, a WGS process SDG of 0.59, and a LTS reactor operating temperature of 473 K. With these fixed variables, a syngas with H2 molar composition of 92.2% and LHV of 12 MJ Nm−3 was attained.

[Understory effects on overstory trees: A review.

Science.gov (United States)

Du, Zhong; Cai, Xiao Hu; Bao, Wei Kai; Chen, Huai; Pan, Hong Li

2016-03-01

Plant-plant interactions play a key role in regulating the composition and structure of communities and ecosystems. Studies of plant-plant interactions in forest ecosystems have traditionally concentrated on either tree-tree interactions or overstory species' impacts on understory plants. The possible effects of understory species on overstory trees have received less attention. We summarized the effects of understory species on soil physiological properties, soil fauna activities, leaf litter decomposition, and ecophysiology and growth of the overstory species. Then the effects of distur-bance on understory-overstory interactions were discussed. Finally, an ecophysiology-based concept model of understory effects on overstory trees was proposed. Understory removal experiments showed that the study area, overstory species age, soil fertility and understory species could significantly affect the understory-overstory interactions.

Aspen Global Change Institute Summer Science Sessions

Energy Technology Data Exchange (ETDEWEB)

Katzenberger, John; Kaye, Jack A

2006-10-01

The Aspen Global Change Institute (AGCI) successfully organized and convened six interdisciplinary meetings over the course of award NNG04GA21G. The topics of the meetings were consistent with a range of issues, goals and objectives as described within the NASA Earth Science Enterprise Strategic Plan and more broadly by the US Global Change Research Program/Our Changing Planet, the more recent Climate Change Program Strategic Plan and the NSF Pathways report. The meetings were chaired by two or more leaders from within the disciplinary focus of each session. 222 scholars for a total of 1097 participants-days were convened under the auspices of this award. The overall goal of each AGCI session is to further the understanding of Earth system science and global environmental change through interdisciplinary dialog. The format and structure of the meetings allows for presentation by each participant, in-depth discussion by the whole group, and smaller working group and synthesis activities. The size of the group is important in terms of the group dynamics and interaction, and the ability for each participant's work to be adequately presented and discussed within the duration of the meeting, while still allowing time for synthesis

FTAP, Minimal Cut Sets of Arbitrary Fault Trees. FRTPLT, Fault Tree Structure and Logical Gates Plot for Program FTAP. FRTGEN, Fault Trees by Sub-tree Generator from Parent Tree for Program FTAP

International Nuclear Information System (INIS)

Willie, Randall R.; Rabien, U.

1997-01-01

1 - Description of problem or function: FTAP is a general-purpose program for deriving minimal reliability cut and path set families from the fault tree for a complex system. The program has a number of useful features that make it well-suited to nearly all fault tree applications. An input fault tree may specify the system state as any logical function of subsystem or component state variables or complements of these variables; thus, for instance, 'exclusive-or' type relations may be formed. When fault tree logical relations involve complements of state variables, the analyst may instruct FTAP to produce a family of prime implicants, a generalization of the minimal cut set concept. The program offers the flexibility of several distinct methods of generating cut set families. FTAP can also identify certain subsystems as system modules and provide a collection of minimal cut set families that essentially expresses the system state as a function of these module state variables. Another feature allows a useful subfamily to be obtained when the family of minimal cut sets or prime implicants is too large to be found in its entirety; this subfamily may consist of only those sets not containing more than some fixed number of elements or only those sets 'interesting' to the analyst in some special sense. Finally, the analyst can modify the input fault tree in various ways by declaring state variables identically true or false. 2 - Method of solution: Fault tree methods are based on the observation that the system state, either working or failed, can usually be expressed as a Boolean relation between states of several large, readily identifiable subsystems. The state of each subsystem in turn depends on states of simpler subsystems and components which compose it, so that the state of the system itself is determined by a hierarchy of logical relationships between states of subsystems. A fault tree is a graphical representation of these relationships. 3 - Restrictions on the

Assessing urban forest effects and values, Scranton's urban forest

Science.gov (United States)

David J. Nowak; Robert E. III Hoehn; Daniel E. Crane; Jack C. Stevens; Vincent. Cotrone

2010-01-01

An analysis of trees in the urbanized portion of Scranton, PA, reveals that this area has about 1.2 million trees with canopies that cover 22.0 percent of the area. The most common tree species are red maple, gray birch, black cherry, northern red oak, and quaking aspen. Scranton's urban forest currently store about 93,300 tons of carbon valued at $1.9 million. In...

Genomics-assisted breeding in fruit trees.

Science.gov (United States)

Iwata, Hiroyoshi; Minamikawa, Mai F; Kajiya-Kanegae, Hiromi; Ishimori, Motoyuki; Hayashi, Takeshi

2016-01-01

Recent advancements in genomic analysis technologies have opened up new avenues to promote the efficiency of plant breeding. Novel genomics-based approaches for plant breeding and genetics research, such as genome-wide association studies (GWAS) and genomic selection (GS), are useful, especially in fruit tree breeding. The breeding of fruit trees is hindered by their long generation time, large plant size, long juvenile phase, and the necessity to wait for the physiological maturity of the plant to assess the marketable product (fruit). In this article, we describe the potential of genomics-assisted breeding, which uses these novel genomics-based approaches, to break through these barriers in conventional fruit tree breeding. We first introduce the molecular marker systems and whole-genome sequence data that are available for fruit tree breeding. Next we introduce the statistical methods for biparental linkage and quantitative trait locus (QTL) mapping as well as GWAS and GS. We then review QTL mapping, GWAS, and GS studies conducted on fruit trees. We also review novel technologies for rapid generation advancement. Finally, we note the future prospects of genomics-assisted fruit tree breeding and problems that need to be overcome in the breeding.

Decision tree methods: applications for classification and prediction.

Science.gov (United States)

Song, Yan-Yan; Lu, Ying

2015-04-25

Decision tree methodology is a commonly used data mining method for establishing classification systems based on multiple covariates or for developing prediction algorithms for a target variable. This method classifies a population into branch-like segments that construct an inverted tree with a root node, internal nodes, and leaf nodes. The algorithm is non-parametric and can efficiently deal with large, complicated datasets without imposing a complicated parametric structure. When the sample size is large enough, study data can be divided into training and validation datasets. Using the training dataset to build a decision tree model and a validation dataset to decide on the appropriate tree size needed to achieve the optimal final model. This paper introduces frequently used algorithms used to develop decision trees (including CART, C4.5, CHAID, and QUEST) and describes the SPSS and SAS programs that can be used to visualize tree structure.

Using fuzzy arithmetic in containment event trees

International Nuclear Information System (INIS)

Rivera, S.S.; Baron, Jorge H.

2000-01-01

The use of fuzzy arithmetic is proposed for the evaluation of containment event trees. Concepts such as improbable, very improbable, and so on, which are subjective by nature, are represented by fuzzy numbers. The quantitative evaluation of containment event trees is based on the extension principle, by which operations on real numbers are extended to operations on fuzzy numbers. Expert knowledge is considered as state of the base variable with a normal distribution, which is considered to represent the membership function. Finally, this paper presents results of an example calculation of a containment event tree for the CAREM-25 nuclear power plant, presently under detailed design stage at Argentina. (author)

3D Visualization of Trees Based on a Sphere-Board Model

Directory of Open Access Journals (Sweden)

Jiangfeng She

2018-01-01

Full Text Available Because of the smooth interaction of tree systems, the billboard and crossed-plane techniques of image-based rendering (IBR have been used for tree visualization for many years. However, both the billboard-based tree model (BBTM and the crossed-plane tree model (CPTM have several notable limitations; for example, they give an impression of slicing when viewed from the top side, and they produce an unimpressive stereoscopic effect and insufficient lighted effects. In this study, a sphere-board-based tree model (SBTM is proposed to eliminate these defects and to improve the final visual effects. Compared with the BBTM or CPTM, the proposed SBTM uses one or more sphere-like 3D geometric surfaces covered with a virtual texture, which can present more details about the foliage than can 2D planes, to represent the 3D outline of a tree crown. However, the profile edge presented by a continuous surface is overly smooth and regular, and when used to delineate the outline of a tree crown, it makes the tree appear very unrealistic. To overcome this shortcoming and achieve a more natural final visual effect of the tree model, an additional process is applied to the edge of the surface profile. In addition, the SBTM can better support lighted effects because of its cubic geometrical features. Interactive visualization effects for a single tree and a grove are presented in a case study of Sabina chinensis. The results show that the SBTM can achieve a better compromise between realism and performance than can the BBTM or CPTM.

The impact of tree age on biomass growth and carbon accumulation capacity: A retrospective analysis using tree ring data of three tropical tree species grown in natural forests of Suriname.

Science.gov (United States)

Köhl, Michael; Neupane, Prem R; Lotfiomran, Neda

2017-01-01

The world's forests play a pivotal role in the mitigation of global climate change. By photosynthesis they remove CO2 from the atmosphere and store carbon in their biomass. While old trees are generally acknowledged for a long carbon residence time, there is no consensus on their contribution to carbon accumulation due to a lack of long-term individual tree data. Tree ring analyses, which use anatomical differences in the annual formation of wood for dating growth zones, are a retrospective approach that provides growth patterns of individual trees over their entire lifetime. We developed time series of diameter growth and related annual carbon accumulation for 61 trees of the species Cedrela odorata L. (Meliacea), Hymenaea courbaril L. (Fabacea) and Goupia glabra Aubl. (Goupiacea). The trees grew in unmanaged tropical wet-forests of Suriname and reached ages from 84 to 255 years. Most of the trees show positive trends of diameter growth and carbon accumulation over time. For some trees we observed fluctuating growth-periods of lower growth alternate with periods of increased growth. In the last quarter of their lifetime trees accumulate on average between 39 percent (C. odorata) and 50 percent (G. glabra) of their final carbon stock. This suggests that old-growth trees in tropical forests do not only contribute to carbon stocks by long carbon resistance times, but maintain high rates of carbon accumulation at later stages of their life time.

Drivers of variability in tree transpiration in a Boreal Black Spruce Forest Chronosequence

Science.gov (United States)

Angstmann, J. L.; Ewers, B. E.; Kwon, H.

2009-12-01

Boreal forests are of particular interest in climate change studies because of their large land area and ability to sequester and store carbon, which is controlled by water availability. Heterogeneity of these forests is predicted to increase with climate change through the impact of more frequent wildfires, warmer, longer growing seasons, and potential drainage of forested wetlands. This study aims to quantify the influence of stand age, drainage condition, and species on tree transpiration and its drivers in a central Canadian black spruce boreal forest. Heat dissipation sensors were installed in 113 trees (69 Picea mariana (black spruce), 25 Populus tremuloides (trembling aspen), and 19 Pinus banksiana (jack pine) at four stand ages, each containing a well- and poorly-drained site over three growing seasons (2006-2008). Sap flux per unit xylem area, JS, was expressed as transpiration per unit ground area, EC, and transpiration per unit leaf area, EL, using site- and species-specific allometry to obtain sapwood area (AS)and leaf area(AL)per unit ground area. Well-drained, younger Picea mariana daily JS was 47-64% greater than the older well-drained burn ages and younger poorly-drained stands were 64-68% greater than the two oldest poorly-drained stands. Daily EL in the well-drained Picea mariana stands was on average 12-33% higher in younger stand than in the two oldest stands whereas young, poorly-drained Picea mariana had 71% greater daily EL than the older stands. Well-drained Picea mariana trees had 52% higher daily EC than older trees and poorly-drained Picea mariana in the 1964 burn had 42-81% higher daily EC than the oldest stands. Populus tremuloides located in the two youngest stands had daily JS 38-58% greater rates than the 1930 burn, whereas daily EL and EC had no distint differences due to high interannual variability. Pinus banksiana experienced 21-33% greater daily JS in the 1989 burn than in the older 1964 burn for well- and poorly-drained sites

Effects of Tropospheric O3 on Trembling Aspen and Interaction with CO2: Results From An O3-Gradient and a Face Experiment

Science.gov (United States)

D.F. Karnosky; B. Mankovska; K. Percy; R.E. Dickson; G.K. Podila; J. Sober; A. Noormets; G. Hendrey; Mark D. Coleman; M. Kubiske; K.S. Pregitzer; J.G. Isebrands

1999-01-01

Abstract. Over the years, a series of trembling aspen (Populus tremuloides Michx.) clones differing in O3 sensitivity have been identified from OTC studies. Three clones (216 and 271[(O3 tolerant] and 259 [O3 sensitive]) have been characterized for O3...

Possibilities for the Use of Wood Ashes in Agriculture

OpenAIRE

Barbara Symanowicz; Marcin Becher; Dawid Jaremko; Korneliusz Skwarek

2018-01-01

The aim of the study was to determine the agricultural usefulness of the ashes obtained following the combustion of wood of fourteen tree species (pear tree, apple tree, aspen, ash, alder, birch, poplar, hornbeam, pine, common walnut, oak, hazel, bird cherry and spruce) in home fireplaces. The following physical properties of the ashes were determined: colour, solubility, porosity, absorbability, compression strength, degree of fineness, moisture content and spreadability. In the ashes...

Laser scanning measurements on trees for logging harvesting operations.

Science.gov (United States)

Zheng, Yili; Liu, Jinhao; Wang, Dian; Yang, Ruixi

2012-01-01

Logging harvesters represent a set of high-performance modern forestry machinery, which can finish a series of continuous operations such as felling, delimbing, peeling, bucking and so forth with human intervention. It is found by experiment that during the process of the alignment of the harvesting head to capture the trunk, the operator needs a lot of observation, judgment and repeated operations, which lead to the time and fuel losses. In order to improve the operation efficiency and reduce the operating costs, the point clouds for standing trees are collected with a low-cost 2D laser scanner. A cluster extracting algorithm and filtering algorithm are used to classify each trunk from the point cloud. On the assumption that every cross section of the target trunk is approximate a standard circle and combining the information of an Attitude and Heading Reference System, the radii and center locations of the trunks in the scanning range are calculated by the Fletcher-Reeves conjugate gradient algorithm. The method is validated through experiments in an aspen forest, and the optimized calculation time consumption is compared with the previous work of other researchers. Moreover, the implementation of the calculation result for automotive capturing trunks by the harvesting head during the logging operation is discussed in particular.

ETE: a python Environment for Tree Exploration.

Science.gov (United States)

Huerta-Cepas, Jaime; Dopazo, Joaquín; Gabaldón, Toni

2010-01-13

Many bioinformatics analyses, ranging from gene clustering to phylogenetics, produce hierarchical trees as their main result. These are used to represent the relationships among different biological entities, thus facilitating their analysis and interpretation. A number of standalone programs are available that focus on tree visualization or that perform specific analyses on them. However, such applications are rarely suitable for large-scale surveys, in which a higher level of automation is required. Currently, many genome-wide analyses rely on tree-like data representation and hence there is a growing need for scalable tools to handle tree structures at large scale. Here we present the Environment for Tree Exploration (ETE), a python programming toolkit that assists in the automated manipulation, analysis and visualization of hierarchical trees. ETE libraries provide a broad set of tree handling options as well as specific methods to analyze phylogenetic and clustering trees. Among other features, ETE allows for the independent analysis of tree partitions, has support for the extended newick format, provides an integrated node annotation system and permits to link trees to external data such as multiple sequence alignments or numerical arrays. In addition, ETE implements a number of built-in analytical tools, including phylogeny-based orthology prediction and cluster validation techniques. Finally, ETE's programmable tree drawing engine can be used to automate the graphical rendering of trees with customized node-specific visualizations. ETE provides a complete set of methods to manipulate tree data structures that extends current functionality in other bioinformatic toolkits of a more general purpose. ETE is free software and can be downloaded from http://ete.cgenomics.org.

ETE: a python Environment for Tree Exploration

Directory of Open Access Journals (Sweden)

Gabaldón Toni

2010-01-01

Full Text Available Abstract Background Many bioinformatics analyses, ranging from gene clustering to phylogenetics, produce hierarchical trees as their main result. These are used to represent the relationships among different biological entities, thus facilitating their analysis and interpretation. A number of standalone programs are available that focus on tree visualization or that perform specific analyses on them. However, such applications are rarely suitable for large-scale surveys, in which a higher level of automation is required. Currently, many genome-wide analyses rely on tree-like data representation and hence there is a growing need for scalable tools to handle tree structures at large scale. Results Here we present the Environment for Tree Exploration (ETE, a python programming toolkit that assists in the automated manipulation, analysis and visualization of hierarchical trees. ETE libraries provide a broad set of tree handling options as well as specific methods to analyze phylogenetic and clustering trees. Among other features, ETE allows for the independent analysis of tree partitions, has support for the extended newick format, provides an integrated node annotation system and permits to link trees to external data such as multiple sequence alignments or numerical arrays. In addition, ETE implements a number of built-in analytical tools, including phylogeny-based orthology prediction and cluster validation techniques. Finally, ETE's programmable tree drawing engine can be used to automate the graphical rendering of trees with customized node-specific visualizations. Conclusions ETE provides a complete set of methods to manipulate tree data structures that extends current functionality in other bioinformatic toolkits of a more general purpose. ETE is free software and can be downloaded from http://ete.cgenomics.org.

Information Literacy: Advancing Opportunities for Learning in the Digital Age. A Report of The Aspen Institute Forum on Communications and Society.

Science.gov (United States)

Adler, Richard P.; Breivik, Patricia Senn

This report is an informed observer's interpretation of the discussions that took place at the 1998 annual meeting of the Aspen Institute's Forum on Communications and Society (FOCAS). It summarizes the inquiry made by FOCAS members into the many issues surrounding information literacy, including what information literacy is, why we need an…

Allometries for Widely Spaced Populus ssp. and Betula ssp. in Nurse Crop Systems

Directory of Open Access Journals (Sweden)

Hendrik Stark

2013-11-01

Full Text Available Nurse crops of widely spaced pioneer trees are a silvicultural approach to protect the regeneration of frost sensitive target tree species. If overstorey nurse crops are harvested, they can provide additional short-term benefits through increased biomass production, e.g., for bioenergy. However, the intensification of biomass exports from forests might impact negatively on ecosystem nutrient pools. Thus, precise allometric biomass equations are required to quantify biomass and nutrient removals. Since an analysis of published allometric equations developed for typical, dense aspen or birch forests showed that the tree height-to-diameter ratio correlated positively and the proportion of branch biomass negatively with stand density, we developed new allometric biomass equations for widely spaced aspen and birch growing at 4 x 4 m spacing. These equations yielded a root mean squared error of 13% when predicting total aboveground woody biomass for our sample trees. In contrast, the corresponding root mean squared error produced by allometric biomass equations from the literature ranged between 17% to 106% of actual dry biomass. Our results show that specific allometric biomass equations are needed for widely spaced pioneer trees both for accurate estimates of biomass and the nutrients contained within.

A knowledge-based approach to the evaluation of fault trees

International Nuclear Information System (INIS)

Hwang, Yann-Jong; Chow, Louis R.; Huang, Henry C.

1996-01-01

A list of critical components is useful for determining the potential problems of a complex system. However, to find this list through evaluating the fault trees is expensive and time consuming. This paper intends to propose an integrated software program which consists of a fault tree constructor, a knowledge base, and an efficient algorithm for evaluating minimal cut sets of a large fault tree. The proposed algorithm uses the approaches of top-down heuristic searching and the probability-based truncation. That makes the evaluation of fault trees obviously efficient and provides critical components for solving the potential problems in complex systems. Finally, some practical fault trees are included to illustrate the results

Molecular and physiological responses to abiotic stress in forest trees and their relevance to tree improvement.

Science.gov (United States)

Harfouche, Antoine; Meilan, Richard; Altman, Arie

2014-11-01

Abiotic stresses, such as drought, salinity and cold, are the major environmental stresses that adversely affect tree growth and, thus, forest productivity, and play a major role in determining the geographic distribution of tree species. Tree responses and tolerance to abiotic stress are complex biological processes that are best analyzed at a systems level using genetic, genomic, metabolomic and phenomic approaches. This will expedite the dissection of stress-sensing and signaling networks to further support efficient genetic improvement programs. Enormous genetic diversity for stress tolerance exists within some forest-tree species, and due to advances in sequencing technologies the molecular genetic basis for this diversity has been rapidly unfolding in recent years. In addition, the use of emerging phenotyping technologies extends the suite of traits that can be measured and will provide us with a better understanding of stress tolerance. The elucidation of abiotic stress-tolerance mechanisms will allow for effective pyramiding of multiple tolerances in a single tree through genetic engineering. Here we review recent progress in the dissection of the molecular basis of abiotic stress tolerance in forest trees, with special emphasis on Populus, Pinus, Picea, Eucalyptus and Quercus spp. We also outline practices that will enable the deployment of trees engineered for abiotic stress tolerance to land owners. Finally, recommendations for future work are discussed. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Safety validation of decision trees for hepatocellular carcinoma.

Science.gov (United States)

Wang, Xian-Qiang; Liu, Zhe; Lv, Wen-Ping; Luo, Ying; Yang, Guang-Yun; Li, Chong-Hui; Meng, Xiang-Fei; Liu, Yang; Xu, Ke-Sen; Dong, Jia-Hong

2015-08-21

To evaluate a different decision tree for safe liver resection and verify its efficiency. A total of 2457 patients underwent hepatic resection between January 2004 and December 2010 at the Chinese PLA General Hospital, and 634 hepatocellular carcinoma (HCC) patients were eligible for the final analyses. Post-hepatectomy liver failure (PHLF) was identified by the association of prothrombin time 50 μmol/L (the "50-50" criteria), which were assessed at day 5 postoperatively or later. The Swiss-Clavien decision tree, Tokyo University-Makuuchi decision tree, and Chinese consensus decision tree were adopted to divide patients into two groups based on those decision trees in sequence, and the PHLF rates were recorded. The overall mortality and PHLF rate were 0.16% and 3.0%. A total of 19 patients experienced PHLF. The numbers of patients to whom the Swiss-Clavien, Tokyo University-Makuuchi, and Chinese consensus decision trees were applied were 581, 573, and 622, and the PHLF rates were 2.75%, 2.62%, and 2.73%, respectively. Significantly more cases satisfied the Chinese consensus decision tree than the Swiss-Clavien decision tree and Tokyo University-Makuuchi decision tree (P decision trees. The Chinese consensus decision tree expands the indications for hepatic resection for HCC patients and does not increase the PHLF rate compared to the Swiss-Clavien and Tokyo University-Makuuchi decision trees. It would be a safe and effective algorithm for hepatectomy in patients with hepatocellular carcinoma.

Categorizing ideas about trees: a tree of trees.

Science.gov (United States)

Fisler, Marie; Lecointre, Guillaume

2013-01-01

The aim of this study is to explore whether matrices and MP trees used to produce systematic categories of organisms could be useful to produce categories of ideas in history of science. We study the history of the use of trees in systematics to represent the diversity of life from 1766 to 1991. We apply to those ideas a method inspired from coding homologous parts of organisms. We discretize conceptual parts of ideas, writings and drawings about trees contained in 41 main writings; we detect shared parts among authors and code them into a 91-characters matrix and use a tree representation to show who shares what with whom. In other words, we propose a hierarchical representation of the shared ideas about trees among authors: this produces a "tree of trees." Then, we categorize schools of tree-representations. Classical schools like "cladists" and "pheneticists" are recovered but others are not: "gradists" are separated into two blocks, one of them being called here "grade theoreticians." We propose new interesting categories like the "buffonian school," the "metaphoricians," and those using "strictly genealogical classifications." We consider that networks are not useful to represent shared ideas at the present step of the study. A cladogram is made for showing who is sharing what with whom, but also heterobathmy and homoplasy of characters. The present cladogram is not modelling processes of transmission of ideas about trees, and here it is mostly used to test for proximity of ideas of the same age and for categorization.

Wood properties of Populus and Betula in long-term exposure to elevated CO₂ and O₃.

Science.gov (United States)

Kostiainen, Katri; Saranpää, Pekka; Lundqvist, Sven-Olof; Kubiske, Mark E; Vapaavuori, Elina

2014-06-01

We studied the interactive effects of elevated concentrations of CO2 and O3 on radial growth and wood properties of four trembling aspen (Populus tremuloides Michx.) clones and paper birch (Betula papyrifera Marsh.) saplings. The material for the study was collected from the Aspen FACE (free-air CO2 enrichment) experiment in Rhinelander (WI, USA). Trees had been exposed to four treatments [control, elevated CO2 (560 ppm), elevated O3 (1.5 times ambient) and combined CO2 + O3 ] during growing seasons 1998-2008. Most treatment responses were observed in the early phase of experiment. Our results show that the CO2- and O3-exposed aspen trees displayed a differential balance between efficiency and safety of water transport. Under elevated CO2, radial growth was enhanced and the trees had fewer but hydraulically more efficient larger diameter vessels. In contrast, elevated O3 decreased radial growth and the diameters of vessels and fibres. Clone-specific decrease in wood density and cell wall thickness was observed under elevated CO2 . In birch, the treatments had no major impacts on wood anatomy or wood density. Our study indicates that short-term impact studies conducted with young seedlings may not give a realistic view of long-term ecosystem responses. © 2013 John Wiley & Sons Ltd.

A simulation study of Solid Oxide fuel cell for IGCC power generation using Aspen Plus

DEFF Research Database (Denmark)

Rudra, Souman; Kim, Hyung Taek

2010-01-01

operating conditions and using diverse fuels. The SOFC stack model developed using the chemical process flow sheet simulator Aspen Plus which is of equilibrium type and is based on Gibbs free energy minimization. The SOFC model performs heat and mass balances and considers the ohmic, activation...... with respect to a variety of SOFC inputs. SOFC stack operation on syn-gas is compared to operation on different coal properties and as expected there is a drop in performance, which is attributed to increased input fuel and air flow due to the lower quality of the fuel gas....

The dynamics of strangling among forest trees.

Science.gov (United States)

Okamoto, Kenichi W

2015-11-07

Strangler trees germinate and grow on other trees, eventually enveloping and potentially even girdling their hosts. This allows them to mitigate fitness costs otherwise incurred by germinating and competing with other trees on the forest floor, as well as minimize risks associated with host tree-fall. If stranglers can themselves host other strangler trees, they may not even seem to need non-stranglers to persist. Yet despite their high fitness potential, strangler trees neither dominate the communities in which they occur nor is the strategy particularly common outside of figs (genus Ficus). Here we analyze how dynamic interactions between strangling and non-strangling trees can shape the adaptive landscape for strangling mutants and mutant trees that have lost the ability to strangle. We find a threshold which strangler germination rates must exceed for selection to favor the evolution of strangling, regardless of how effectively hemiepiphytic stranglers may subsequently replace their hosts. This condition describes the magnitude of the phenotypic displacement in the ability to germinate on other trees necessary for invasion by a mutant tree that could potentially strangle its host following establishment as an epiphyte. We show how the relative abilities of strangling and non-strangling trees to occupy empty sites can govern whether strangling is an evolutionarily stable strategy, and obtain the conditions for strangler coexistence with non-stranglers. We then elucidate when the evolution of strangling can disrupt stable coexistence between commensal epiphytic ancestors and their non-strangling host trees. This allows us to highlight parallels between the invasion fitness of strangler trees arising from commensalist ancestors, and cases where strangling can arise in concert with the evolution of hemiepiphytism among free-standing ancestors. Finally, we discuss how our results can inform the evolutionary ecology of antagonistic interactions more generally

An efficient and extensible approach for compressing phylogenetic trees.

Science.gov (United States)

Matthews, Suzanne J; Williams, Tiffani L

2011-10-18

Biologists require new algorithms to efficiently compress and store their large collections of phylogenetic trees. Our previous work showed that TreeZip is a promising approach for compressing phylogenetic trees. In this paper, we extend our TreeZip algorithm by handling trees with weighted branches. Furthermore, by using the compressed TreeZip file as input, we have designed an extensible decompressor that can extract subcollections of trees, compute majority and strict consensus trees, and merge tree collections using set operations such as union, intersection, and set difference. On unweighted phylogenetic trees, TreeZip is able to compress Newick files in excess of 98%. On weighted phylogenetic trees, TreeZip is able to compress a Newick file by at least 73%. TreeZip can be combined with 7zip with little overhead, allowing space savings in excess of 99% (unweighted) and 92%(weighted). Unlike TreeZip, 7zip is not immune to branch rotations, and performs worse as the level of variability in the Newick string representation increases. Finally, since the TreeZip compressed text (TRZ) file contains all the semantic information in a collection of trees, we can easily filter and decompress a subset of trees of interest (such as the set of unique trees), or build the resulting consensus tree in a matter of seconds. We also show the ease of which set operations can be performed on TRZ files, at speeds quicker than those performed on Newick or 7zip compressed Newick files, and without loss of space savings. TreeZip is an efficient approach for compressing large collections of phylogenetic trees. The semantic and compact nature of the TRZ file allow it to be operated upon directly and quickly, without a need to decompress the original Newick file. We believe that TreeZip will be vital for compressing and archiving trees in the biological community.

Boosted classification trees result in minor to modest improvement in the accuracy in classifying cardiovascular outcomes compared to conventional classification trees

Science.gov (United States)

Austin, Peter C; Lee, Douglas S

2011-01-01

Purpose: Classification trees are increasingly being used to classifying patients according to the presence or absence of a disease or health outcome. A limitation of classification trees is their limited predictive accuracy. In the data-mining and machine learning literature, boosting has been developed to improve classification. Boosting with classification trees iteratively grows classification trees in a sequence of reweighted datasets. In a given iteration, subjects that were misclassified in the previous iteration are weighted more highly than subjects that were correctly classified. Classifications from each of the classification trees in the sequence are combined through a weighted majority vote to produce a final classification. The authors' objective was to examine whether boosting improved the accuracy of classification trees for predicting outcomes in cardiovascular patients. Methods: We examined the utility of boosting classification trees for classifying 30-day mortality outcomes in patients hospitalized with either acute myocardial infarction or congestive heart failure. Results: Improvements in the misclassification rate using boosted classification trees were at best minor compared to when conventional classification trees were used. Minor to modest improvements to sensitivity were observed, with only a negligible reduction in specificity. For predicting cardiovascular mortality, boosted classification trees had high specificity, but low sensitivity. Conclusions: Gains in predictive accuracy for predicting cardiovascular outcomes were less impressive than gains in performance observed in the data mining literature. PMID:22254181

A Minimum Spanning Tree Representation of Anime Similarities

OpenAIRE

Wibowo, Canggih Puspo

2016-01-01

In this work, a new way to represent Japanese animation (anime) is presented. We applied a minimum spanning tree to show the relation between anime. The distance between anime is calculated through three similarity measurements, namely crew, score histogram, and topic similarities. Finally, the centralities are also computed to reveal the most significance anime. The result shows that the minimum spanning tree can be used to determine the similarity anime. Furthermore, by using centralities c...

Water, gravity and trees: Relationship of tree-ring widths and total water storage dynamics

Science.gov (United States)

Creutzfeldt, B.; Heinrich, I.; Merz, B.; Blume, T.; Güntner, A.

2012-04-01

Water stored in the subsurface as groundwater or soil moisture is the main fresh water source not only for drinking water and food production but also for the natural vegetation. In a changing environment water availability becomes a critical issue in many different regions. Long-term observations of the past are needed to improve the understanding of the hydrological system and the prediction of future developments. Tree ring data have repeatedly proved to be valuable sources for reconstructing long-term climate dynamics, e.g. temperature, precipitation and different hydrological variables. In water-limited environments, tree growth is primarily influenced by total water stored in the subsurface and hence, tree-ring records usually contain information about subsurface water storage. The challenge is to retrieve the information on total water storage from tree rings, because a training dataset of water stored in the sub-surface is required for calibration against the tree-ring series. However, measuring water stored in the subsurface is notoriously difficult. We here present high-precision temporal gravimeter measurements which allow for the depth-integrated quantification of total water storage dynamics at the field scale. In this study, we evaluate the relationship of total water storage change and tree ring growth also in the context of the complex interactions of other meteorological forcing factors. A tree-ring chronology was derived from a Norway spruce stand in the Bavarian Forest, Germany. Total water storage dynamics were measured directly by the superconducting gravimeter of the Geodetic Observatory Wettzell for a 9-years period. Time series were extended to 63-years period by a hydrological model using gravity data as the only calibration constrain. Finally, water storage changes were reconstructed based on the relationship between the hydrological model and the tree-ring chronology. Measurement results indicate that tree-ring growth is primarily

Interactive tree of life (iTOL) v3: an online tool for the display and annotation of phylogenetic and other trees.

Science.gov (United States)

Letunic, Ivica; Bork, Peer

2016-07-08

Interactive Tree Of Life (http://itol.embl.de) is a web-based tool for the display, manipulation and annotation of phylogenetic trees. It is freely available and open to everyone. The current version was completely redesigned and rewritten, utilizing current web technologies for speedy and streamlined processing. Numerous new features were introduced and several new data types are now supported. Trees with up to 100,000 leaves can now be efficiently displayed. Full interactive control over precise positioning of various annotation features and an unlimited number of datasets allow the easy creation of complex tree visualizations. iTOL 3 is the first tool which supports direct visualization of the recently proposed phylogenetic placements format. Finally, iTOL's account system has been redesigned to simplify the management of trees in user-defined workspaces and projects, as it is heavily used and currently handles already more than 500,000 trees from more than 10,000 individual users. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

Commercial application of fault tree analysis

International Nuclear Information System (INIS)

Crosetti, P.A.; Bruce, R.A.

1970-01-01

The potential for general application of Fault Tree Analysis to commercial products appears attractive based not only on the successful extension from the aerospace safety technology to the nuclear reactor reliability and availability technology, but also because combinatorial hazards are common to commercial operations and therefore lend themselves readily to evaluation by Fault Tree Analysis. It appears reasonable to conclude that the technique has application within the commercial industrial community where the occurrence of a specified consequence or final event would be of sufficient concern to management to justify such a rigorous analysis as an aid to decision making. (U.S.)

Deterministic Automata for Unordered Trees

Directory of Open Access Journals (Sweden)

Adrien Boiret

2014-08-01

Full Text Available Automata for unordered unranked trees are relevant for defining schemas and queries for data trees in Json or Xml format. While the existing notions are well-investigated concerning expressiveness, they all lack a proper notion of determinism, which makes it difficult to distinguish subclasses of automata for which problems such as inclusion, equivalence, and minimization can be solved efficiently. In this paper, we propose and investigate different notions of "horizontal determinism", starting from automata for unranked trees in which the horizontal evaluation is performed by finite state automata. We show that a restriction to confluent horizontal evaluation leads to polynomial-time emptiness and universality, but still suffers from coNP-completeness of the emptiness of binary intersections. Finally, efficient algorithms can be obtained by imposing an order of horizontal evaluation globally for all automata in the class. Depending on the choice of the order, we obtain different classes of automata, each of which has the same expressiveness as CMso.

PROVIDING R-TREE SUPPORT FOR MONGODB

Directory of Open Access Journals (Sweden)

L. Xiang

2016-06-01

Full Text Available Supporting large amounts of spatial data is a significant characteristic of modern databases. However, unlike some mature relational databases, such as Oracle and PostgreSQL, most of current burgeoning NoSQL databases are not well designed for storing geospatial data, which is becoming increasingly important in various fields. In this paper, we propose a novel method to provide R-tree index, as well as corresponding spatial range query and nearest neighbour query functions, for MongoDB, one of the most prevalent NoSQL databases. First, after in-depth analysis of MongoDB’s features, we devise an efficient tabular document structure which flattens R-tree index into MongoDB collections. Further, relevant mechanisms of R-tree operations are issued, and then we discuss in detail how to integrate R-tree into MongoDB. Finally, we present the experimental results which show that our proposed method out-performs the built-in spatial index of MongoDB. Our research will greatly facilitate big data management issues with MongoDB in a variety of geospatial information applications.

Providing R-Tree Support for Mongodb

Science.gov (United States)

Xiang, Longgang; Shao, Xiaotian; Wang, Dehao

2016-06-01

Supporting large amounts of spatial data is a significant characteristic of modern databases. However, unlike some mature relational databases, such as Oracle and PostgreSQL, most of current burgeoning NoSQL databases are not well designed for storing geospatial data, which is becoming increasingly important in various fields. In this paper, we propose a novel method to provide R-tree index, as well as corresponding spatial range query and nearest neighbour query functions, for MongoDB, one of the most prevalent NoSQL databases. First, after in-depth analysis of MongoDB's features, we devise an efficient tabular document structure which flattens R-tree index into MongoDB collections. Further, relevant mechanisms of R-tree operations are issued, and then we discuss in detail how to integrate R-tree into MongoDB. Finally, we present the experimental results which show that our proposed method out-performs the built-in spatial index of MongoDB. Our research will greatly facilitate big data management issues with MongoDB in a variety of geospatial information applications.

Detecting early warning signals of tree mortality in boreal North America using multiscale satellite data.

Science.gov (United States)

Rogers, Brendan M; Solvik, Kylen; Hogg, Edward H; Ju, Junchang; Masek, Jeffrey G; Michaelian, Michael; Berner, Logan T; Goetz, Scott J

2018-02-26

Increasing tree mortality from global change drivers such as drought and biotic infestations is a widespread phenomenon, including in the boreal zone where climate changes and feedbacks to the Earth system are relatively large. Despite the importance for science and management communities, our ability to forecast tree mortality at landscape to continental scales is limited. However, two independent information streams have the potential to inform and improve mortality forecasts: repeat forest inventories and satellite remote sensing. Time series of tree-level growth patterns indicate that productivity declines and related temporal dynamics often precede mortality years to decades before death. Plot-level productivity, in turn, has been related to satellite-based indices such as the Normalized difference vegetation index (NDVI). Here we link these two data sources to show that early warning signals of mortality are evident in several NDVI-based metrics up to 24 years before death. We focus on two repeat forest inventories and three NDVI products across western boreal North America where productivity and mortality dynamics are influenced by periodic drought. These data sources capture a range of forest conditions and spatial resolution to highlight the sensitivity and limitations of our approach. Overall, results indicate potential to use satellite NDVI for early warning signals of mortality. Relationships are broadly consistent across inventories, species, and spatial resolutions, although the utility of coarse-scale imagery in the heterogeneous aspen parkland was limited. Longer-term NDVI data and annually remeasured sites with high mortality levels generate the strongest signals, although we still found robust relationships at sites remeasured at a typical 5 year frequency. The approach and relationships developed here can be used as a basis for improving forest mortality models and monitoring systems. © 2018 John Wiley & Sons Ltd.

The impact of vessel size on vulnerability curves: data and models for within-species variability in saplings of aspen, Populus tremuloides Michx.

Science.gov (United States)

Cai, Jing; Tyree, Melvin T

2010-07-01

The objective of this study was to quantify the relationship between vulnerability to cavitation and vessel diameter within a species. We measured vulnerability curves (VCs: percentage loss hydraulic conductivity versus tension) in aspen stems and measured vessel-size distributions. Measurements were done on seed-grown, 4-month-old aspen (Populus tremuloides Michx) grown in a greenhouse. VCs of stem segments were measured using a centrifuge technique and by a staining technique that allowed a VC to be constructed based on vessel diameter size-classes (D). Vessel-based VCs were also fitted to Weibull cumulative distribution functions (CDF), which provided best-fit values of Weibull CDF constants (c and b) and P(50) = the tension causing 50% loss of hydraulic conductivity. We show that P(50) = 6.166D(-0.3134) (R(2) = 0.995) and that b and 1/c are both linear functions of D with R(2) > 0.95. The results are discussed in terms of models of VCs based on vessel D size-classes and in terms of concepts such as the 'pit area hypothesis' and vessel pathway redundancy.

A new methodology for the computer-aided construction of fault trees

International Nuclear Information System (INIS)

Salem, S.L.; Apostolakis, G.E.; Okrent, D.

1977-01-01

A methodology for systematically constructing fault trees for general complex systems is developed. A means of modeling component behaviour via decision tables is presented, and a procedure, and a procedure for constructing and editing fault trees, either manually or by computer, is developed. The techniques employed result in a complete fault tree in standard form. In order to demonstrate the methodology, the computer program CAT was developed and is used to construct trees for a nuclear system. By analyzing and comparing these fault trees, several conclusions are reached. First, such an approach can be used to produce fault trees that accurately describe system behaviour. Second, multiple trees can be rapidly produced by defining various TOP events, including system success. Finally, the accuracy and utility of such trees is shown to depend upon the careful development of the decision table models by the analyst, and of the overall system definition itself. Thus the method is seen to be a tool for assisting in the work of fault tree construction rather than a replacement for the careful work of the fault tree analyst. (author)

Posbist fault tree analysis of coherent systems

International Nuclear Information System (INIS)

Huang, H.-Z.; Tong Xin; Zuo, Ming J.

2004-01-01

When the failure probability of a system is extremely small or necessary statistical data from the system is scarce, it is very difficult or impossible to evaluate its reliability and safety with conventional fault tree analysis (FTA) techniques. New techniques are needed to predict and diagnose such a system's failures and evaluate its reliability and safety. In this paper, we first provide a concise overview of FTA. Then, based on the posbist reliability theory, event failure behavior is characterized in the context of possibility measures and the structure function of the posbist fault tree of a coherent system is defined. In addition, we define the AND operator and the OR operator based on the minimal cut of a posbist fault tree. Finally, a model of posbist fault tree analysis (posbist FTA) of coherent systems is presented. The use of the model for quantitative analysis is demonstrated with a real-life safety system

Multimodel simulations of forest harvesting effects on long‐term productivity and CN cycling in aspen forests.

Science.gov (United States)

Wang, Fugui; Mladenoff, David J; Forrester, Jodi A; Blanco, Juan A; Schelle, Robert M; Peckham, Scott D; Keough, Cindy; Lucash, Melissa S; Gower, Stith T

The effects of forest management on soil carbon (C) and nitrogen (N) dynamics vary by harvest type and species. We simulated long-term effects of bole-only harvesting of aspen (Populus tremuloides) on stand productivity and interaction of CN cycles with a multiple model approach. Five models, Biome-BGC, CENTURY, FORECAST, LANDIS-II with Century-based soil dynamics, and PnET-CN, were run for 350 yr with seven harvesting events on nutrient-poor, sandy soils representing northwestern Wisconsin, United States. Twenty CN state and flux variables were summarized from the models' outputs and statistically analyzed using ordination and variance analysis methods. The multiple models' averages suggest that bole-only harvest would not significantly affect long-term site productivity of aspen, though declines in soil organic matter and soil N were significant. Along with direct N removal by harvesting, extensive leaching after harvesting before canopy closure was another major cause of N depletion. These five models were notably different in output values of the 20 variables examined, although there were some similarities for certain variables. PnET-CN produced unique results for every variable, and CENTURY showed fewer outliers and similar temporal patterns to the mean of all models. In general, we demonstrated that when there are no site-specific data for fine-scale calibration and evaluation of a single model, the multiple model approach may be a more robust approach for long-term simulations. In addition, multimodeling may also improve the calibration and evaluation of an individual model.

Colocalization of low-methylesterified pectins and Pb deposits in the apoplast of aspen roots exposed to lead

International Nuclear Information System (INIS)

Rabęda, Irena; Bilski, Henryk; Mellerowicz, Ewa J.; Napieralska, Anna; Suski, Szymon; Woźny, Adam; Krzesłowska, Magdalena

2015-01-01

Low-methylesterified homogalacturonans have been suggested to play a role in the binding and immobilization of Pb in CW. Using root apices of hybrid aspen, a plant with a high phytoremediation potential, as a model, we demonstrated that the in situ distribution pattern of low-methylesterified homogalacturonan, pectin epitope (JIM5-P), reflects the pattern of Pb occurrence. The region which indicated high JIM5-P level corresponded with “Pb accumulation zone”. Moreover, JIM5-P was especially abundant in cell junctions, CWs lining the intercellular spaces and the corners of intercellular spaces indicating the highest accumulation of Pb. Furthermore, JIM5-P and Pb commonly co-localized. The observations indicate that low-methylesterified homogalacturonan is the CW polymer that determines the capacity of CW for Pb sequestration. Our results suggest a promising directions for CW modification for enhancing the efficiency of plant roots in Pb accumulation, an important aspect in the phytoremediation of soils contaminated with trace metals. - Highlights: • Co-localization of low-methylesterified pectins and Pb was analysed in situ. • The pattern of Pb accumulation matched low-methylesterified pectins distribution. • Low-methylesterified pectins and Pb commonly co-localized in cell walls. • Low-methylesterified pectins revealed an important compound in Pb sequestration. • We suggest a new direction in enhancing plant efficiency for phytoremediation. - The distribution of lead in developing tissues of aspen root tips exposed to short-term lead treatment mimics the distribution of low-methylesterified pectin epitope

An efficient and extensible approach for compressing phylogenetic trees

KAUST Repository

Matthews, Suzanne J

2011-01-01

Background: Biologists require new algorithms to efficiently compress and store their large collections of phylogenetic trees. Our previous work showed that TreeZip is a promising approach for compressing phylogenetic trees. In this paper, we extend our TreeZip algorithm by handling trees with weighted branches. Furthermore, by using the compressed TreeZip file as input, we have designed an extensible decompressor that can extract subcollections of trees, compute majority and strict consensus trees, and merge tree collections using set operations such as union, intersection, and set difference.Results: On unweighted phylogenetic trees, TreeZip is able to compress Newick files in excess of 98%. On weighted phylogenetic trees, TreeZip is able to compress a Newick file by at least 73%. TreeZip can be combined with 7zip with little overhead, allowing space savings in excess of 99% (unweighted) and 92%(weighted). Unlike TreeZip, 7zip is not immune to branch rotations, and performs worse as the level of variability in the Newick string representation increases. Finally, since the TreeZip compressed text (TRZ) file contains all the semantic information in a collection of trees, we can easily filter and decompress a subset of trees of interest (such as the set of unique trees), or build the resulting consensus tree in a matter of seconds. We also show the ease of which set operations can be performed on TRZ files, at speeds quicker than those performed on Newick or 7zip compressed Newick files, and without loss of space savings.Conclusions: TreeZip is an efficient approach for compressing large collections of phylogenetic trees. The semantic and compact nature of the TRZ file allow it to be operated upon directly and quickly, without a need to decompress the original Newick file. We believe that TreeZip will be vital for compressing and archiving trees in the biological community. © 2011 Matthews and Williams; licensee BioMed Central Ltd.

Dual RBFNNs-Based Model-Free Adaptive Control With Aspen HYSYS Simulation.

Science.gov (United States)

Zhu, Yuanming; Hou, Zhongsheng; Qian, Feng; Du, Wenli

2017-03-01

In this brief, we propose a new data-driven model-free adaptive control (MFAC) method with dual radial basis function neural networks (RBFNNs) for a class of discrete-time nonlinear systems. The main novelty lies in that it provides a systematic design method for controller structure by the direct usage of I/O data, rather than using the first-principle model or offline identified plant model. The controller structure is determined by equivalent-dynamic-linearization representation of the ideal nonlinear controller, and the controller parameters are tuned by the pseudogradient information extracted from the I/O data of the plant, which can deal with the unknown nonlinear system. The stability of the closed-loop control system and the stability of the training process for RBFNNs are guaranteed by rigorous theoretical analysis. Meanwhile, the effectiveness and the applicability of the proposed method are further demonstrated by the numerical example and Aspen HYSYS simulation of distillation column in crude styrene produce process.

Utilization of steam- and explosion-decompressed aspen wood by some anaerobes. [Acetivibrio cellulolyticus, Clostridium saccharolyticum, Zymomonas anaerobia

Energy Technology Data Exchange (ETDEWEB)

Khan, A W; Asther, M; Giuliano, C

1984-01-01

Tests made to study the suitability of using steam- and explosion-decompressed aspen wood as substrate in anaerobic fermentations indicated that after washing with dilute NaOH it becomes over 80% accessible to both mesophilic and thermophilic cellulolytic anaerobes and cellulases, compared with delignified, ball-milled pulp. After washing, this material was also found to be suitable for the single-step conversion of cellulose to ethanol using cocultures consisting of cellylolytic and ethanol-producing saccharolytic anaerobes; and without and after washing by the use of cellulolytic enzymes and ethanologenic anaerobes. 16 references, 3 tables.

Section-Based Tree Species Identification Using Airborne LIDAR Point Cloud

Science.gov (United States)

Yao, C.; Zhang, X.; Liu, H.

2017-09-01

The application of LiDAR data in forestry initially focused on mapping forest community, particularly and primarily intended for largescale forest management and planning. Then with the smaller footprint and higher sampling density LiDAR data available, detecting individual tree overstory, estimating crowns parameters and identifying tree species are demonstrated practicable. This paper proposes a section-based protocol of tree species identification taking palm tree as an example. Section-based method is to detect objects through certain profile among different direction, basically along X-axis or Y-axis. And this method improve the utilization of spatial information to generate accurate results. Firstly, separate the tree points from manmade-object points by decision-tree-based rules, and create Crown Height Mode (CHM) by subtracting the Digital Terrain Model (DTM) from the digital surface model (DSM). Then calculate and extract key points to locate individual trees, thus estimate specific tree parameters related to species information, such as crown height, crown radius, and cross point etc. Finally, with parameters we are able to identify certain tree species. Comparing to species information measured on ground, the portion correctly identified trees on all plots could reach up to 90.65 %. The identification result in this research demonstrate the ability to distinguish palm tree using LiDAR point cloud. Furthermore, with more prior knowledge, section-based method enable the process to classify trees into different classes.

Statistically Consistent k-mer Methods for Phylogenetic Tree Reconstruction.

Science.gov (United States)

Allman, Elizabeth S; Rhodes, John A; Sullivant, Seth

2017-02-01

Frequencies of k-mers in sequences are sometimes used as a basis for inferring phylogenetic trees without first obtaining a multiple sequence alignment. We show that a standard approach of using the squared Euclidean distance between k-mer vectors to approximate a tree metric can be statistically inconsistent. To remedy this, we derive model-based distance corrections for orthologous sequences without gaps, which lead to consistent tree inference. The identifiability of model parameters from k-mer frequencies is also studied. Finally, we report simulations showing that the corrected distance outperforms many other k-mer methods, even when sequences are generated with an insertion and deletion process. These results have implications for multiple sequence alignment as well since k-mer methods are usually the first step in constructing a guide tree for such algorithms.

Tree compression with top trees

DEFF Research Database (Denmark)

Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

2013-01-01

We introduce a new compression scheme for labeled trees based on top trees [3]. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

Tree compression with top trees

DEFF Research Database (Denmark)

Bille, Philip; Gørtz, Inge Li; Landau, Gad M.

2015-01-01

We introduce a new compression scheme for labeled trees based on top trees. Our compression scheme is the first to simultaneously take advantage of internal repeats in the tree (as opposed to the classical DAG compression that only exploits rooted subtree repeats) while also supporting fast...

Size-mediated tree transpiration along soil drainage gradients in a boreal black spruce forest wildfire chronosequence.

Science.gov (United States)

Angstmann, J L; Ewers, B E; Kwon, H

2012-05-01

Boreal forests are crucial to climate change predictions because of their large land area and ability to sequester and store carbon, which is controlled by water availability. Heterogeneity of these forests is predicted to increase with climate change through more frequent wildfires, warmer, longer growing seasons and potential drainage of forested wetlands. This study aims at quantifying controls over tree transpiration with drainage condition, stand age and species in a central Canadian black spruce boreal forest. Heat dissipation sensors were installed in 2007 and data were collected through 2008 on 118 trees (69 Picea mariana (Mill.) Britton, Sterns & Poggenb. (black spruce), 25 Populus tremuloides Michx. (trembling aspen), 19 Pinus banksiana Lamb. (jack pine), 3 Larix laricina (Du Roi) K. Koch (tamarack) and 2 Salix spp. (willow)) at four stand ages (18, 43, 77 and 157 years old) each containing a well- and poorly-drained stand. Transpiration estimates from sap flux were expressed per unit xylem area, J(S), per unit ground area, E(C) and per unit leaf area, E(L), using sapwood (A(S)) and leaf (A(L)) area calculated from stand- and species-specific allometry. Soil drainage differences in transpiration were variable; only the 43- and 157-year-old poorly-drained stands had ∼ 50% higher total stand E(C) than well-drained locations. Total stand E(C) tended to decrease with stand age after an initial increase between the 18- and 43-year-old stands. Soil drainage differences in transpiration were controlled primarily by short-term physiological drivers such as vapor pressure deficit and soil moisture whereas stand age differences were controlled by successional species shifts and changes in tree size (i.e., A(S)). Future predictions of boreal climate change must include stand age, species and soil drainage heterogeneity to avoid biased estimates of forest water loss and latent energy exchanges.

Online community marketing of ski resorts : an in-depth best practice study of aspen/snowmass and breckenridge ski resort

OpenAIRE

Kráľ, Branislav

2013-01-01

Online brand community is a novel phenomenon that carries a number of benefits, but lack of clarity in antecedents of its effectiveness as a marketing alternative. Aspen/Snowmass and Breckenridge Ski Resort are two leading players in the ski industry, and this paper analyzes their activity in-depth in order to bring clarity by extracting implications on best practice. For the purpose, a tailor-made methodology is constructed. It consists of combining two analytical frameworks, interviews with...

Recent drought-induced decline of forests along a water-balance tipping point for ecosystems in western Canada

Science.gov (United States)

Hogg, E. H.; Michaelian, M.

2017-12-01

In western Canada, the forest-prairie boundary corresponds to a hydrologically-defined ecosystem "tipping point" where long-term precipitation is barely sufficient to meet the water use requirements of healthy, closed-canopy forests. In the province of Alberta, the severe subcontinental drought of 2001-2002 heralded the beginning of a 15-year dry period, representing a northward incursion of prairie-like climates into boreal and cordilleran forests. This poses a significant concern for ecosystem functioning of these forests, given GCM projections for continued warming and drying under anthropogenic climate change during this century. Through a multi-scale monitoring approach, we have examined the regional-scale impacts of recent droughts and associated climatic drying on the productivity and health of two important boreal tree species: aspen (Populus tremuloides) and white spruce (Picea glauca). For aspen, the 2016 re-measurement of a regional network of 150 ground plots revealed that tree mortality has escalated, especially in stands exposed to the combined impacts of multi-year drought and insect defoliation. On average, mortality losses exceeded growth gains during 2000-2016 for the 54 aspen plots in Alberta, leading to a net multi-year decline in the aboveground biomass of these stands. For white spruce, tree-ring analysis of 40 stands across Alberta revealed that the prolonged dry period led to a 38% decline in average, tree-level growth in aboveground biomass. In both species, stand age was not a significant factor affecting forest sensitivity to drought and climatic drying, suggesting that these forests are at risk if the trend toward more frequent, severe drought continues in the region.

Persistent Effects of Fire Severity on Early Successional Forests in Interior Alaska

Science.gov (United States)

Shenoy, Aditi; Johnstone, Jill F.; Kasischke, Eric S.; Kielland, Knut

2011-01-01

There has been a recent increase in the frequency and extent of wildfires in interior Alaska, and this trend is predicted to continue under a warming climate. Although less well documented, corresponding increases in fire severity are expected. Previous research from boreal forests in Alaska and western Canada indicate that severe fire promotes the recruitment of deciduous tree species and decreases the relative abundance of black spruce (Picea mariana) immediately after fire. Here we extend these observations by (1) examining changes in patterns of aspen and spruce density and biomass that occurred during the first two decades of post-fire succession, and (2) comparing patterns of tree composition in relation to variations in post-fire organic layer depth in four burned black spruce forests in interior Alaska after 10-20 years of succession.Wefound that initial effects of fire severity on recruitment and establishment of aspen and black spruce were maintained by subsequent effects of organic layer depth and initial plant biomass on plant growth during post-fire succession. The proportional contribution of aspen (Populus tremuloides) to total stand biomass remained above 90% during the first and second decades of succession in severely burned sites, while in lightly burned sites the proportional contribution of aspen was reduced due to a 40- fold increase in spruce biomass in these sites. Relationships between organic layer depth and stem density and biomass were consistently negative for aspen, and positive or neutral for black spruce in all four burns. Our results suggest that initial effects of post-fire organic layer depths on deciduous recruitment are likely to translate into a prolonged phase of deciduous dominance during post-fire succession in severely burned stands. This shift in vegetation distribution has important implications for climate-albedo feedbacks, future fire regime, wildlife habitat quality and natural resources for indigenous subsistence

Building of fuzzy decision trees using ID3 algorithm

Science.gov (United States)

Begenova, S. B.; Avdeenko, T. V.

2018-05-01

Decision trees are widely used in the field of machine learning and artificial intelligence. Such popularity is due to the fact that with the help of decision trees graphic models, text rules can be built and they are easily understood by the final user. Because of the inaccuracy of observations, uncertainties, the data, collected in the environment, often take an unclear form. Therefore, fuzzy decision trees becoming popular in the field of machine learning. This article presents a method that includes the features of the two above-mentioned approaches: a graphical representation of the rules system in the form of a tree and a fuzzy representation of the data. The approach uses such advantages as high comprehensibility of decision trees and the ability to cope with inaccurate and uncertain information in fuzzy representation. The received learning method is suitable for classifying problems with both numerical and symbolic features. In the article, solution illustrations and numerical results are given.

Experimental Design for CMIP6: Aerosol, Land Use, and Future Scenarios Final Report

Energy Technology Data Exchange (ETDEWEB)

Arnott, James [AGCI

2015-10-30

The Aspen Global Change Institute hosted a technical science workshop entitled, “Experimental design for CMIP6: Aerosol, Land Use, and Future Scenarios,” on August 3-8, 2014 in Aspen, CO. Claudia Tebaldi (NCAR) and Brian O’Neill (NCAR) served as co-chairs for the workshop. The Organizing committee also included Dave Lawrence (NCAR), Jean-Francois Lamarque (NCAR), George Hurtt (University of Maryland), & Detlef van Vuuren (PBL Netherlands Environmental Change). The meeting included the participation of 22 scientists representing many of the major climate modeling centers for a total of 110 participant days.

Generalising tree traversals and tree transformations to DAGs

DEFF Research Database (Denmark)

Bahr, Patrick; Axelsson, Emil

2017-01-01

We present a recursion scheme based on attribute grammars that can be transparently applied to trees and acyclic graphs. Our recursion scheme allows the programmer to implement a tree traversal or a tree transformation and then apply it to compact graph representations of trees instead. The resul......We present a recursion scheme based on attribute grammars that can be transparently applied to trees and acyclic graphs. Our recursion scheme allows the programmer to implement a tree traversal or a tree transformation and then apply it to compact graph representations of trees instead...... as the complementing theory with a number of examples....

An enhanced component connection method for conversion of fault trees to binary decision diagrams

International Nuclear Information System (INIS)

Remenyte-Prescott, R.; Andrews, J.D.

2008-01-01

Fault tree analysis (FTA) is widely applied to assess the failure probability of industrial systems. Many computer packages are available, which are based on conventional kinetic tree theory methods. When dealing with large (possibly non-coherent) fault trees, the limitations of the technique in terms of accuracy of the solutions and the efficiency of the processing time become apparent. Over recent years, the binary decision diagram (BDD) method has been developed that solves fault trees and overcomes the disadvantages of the conventional FTA approach. First of all, a fault tree for a particular system failure mode is constructed and then converted to a BDD for analysis. This paper analyses alternative methods for the fault tree to BDD conversion process. For most fault tree to BDD conversion approaches, the basic events of the fault tree are placed in an ordering. This can dramatically affect the size of the final BDD and the success of qualitative and quantitative analyses of the system. A set of rules is then applied to each gate in the fault tree to generate the BDD. An alternative approach can also be used, where BDD constructs for each of the gate types are first built and then merged to represent a parent gate. A powerful and efficient property, sub-node sharing, is also incorporated in the enhanced method proposed in this paper. Finally, a combined approach is developed taking the best features of the alternative methods. The efficiency of the techniques is analysed and discussed

Modeling the Ecosystem Services Provided by Trees in Urban Ecosystems: Using Biome-BGC to Improve i-Tree Eco

Science.gov (United States)

Brown, Molly E.; McGroddy, Megan; Spence, Caitlin; Flake, Leah; Sarfraz, Amna; Nowak, David J.; Milesi, Cristina

2012-01-01

As the world becomes increasingly urban, the need to quantify the effect of trees in urban environments on energy usage, air pollution, local climate and nutrient run-off has increased. By identifying, quantifying and valuing the ecological activity that provides services in urban areas, stronger policies and improved quality of life for urban residents can be obtained. Here we focus on two radically different models that can be used to characterize urban forests. The i-Tree Eco model (formerly UFORE model) quantifies ecosystem services (e.g., air pollution removal, carbon storage) and values derived from urban trees based on field measurements of trees and local ancillary data sets. Biome-BGC (Biome BioGeoChemistry) is used to simulate the fluxes and storage of carbon, water, and nitrogen in natural environments. This paper compares i-Tree Eco's methods to those of Biome-BGC, which estimates the fluxes and storage of energy, carbon, water and nitrogen for vegetation and soil components of the ecosystem. We describe the two models and their differences in the way they calculate similar properties, with a focus on carbon and nitrogen. Finally, we discuss the implications of further integration of these two communities for land managers such as those in Maryland.

Creating ensembles of oblique decision trees with evolutionary algorithms and sampling

Science.gov (United States)

Cantu-Paz, Erick [Oakland, CA; Kamath, Chandrika [Tracy, CA

2006-06-13

A decision tree system that is part of a parallel object-oriented pattern recognition system, which in turn is part of an object oriented data mining system. A decision tree process includes the step of reading the data. If necessary, the data is sorted. A potential split of the data is evaluated according to some criterion. An initial split of the data is determined. The final split of the data is determined using evolutionary algorithms and statistical sampling techniques. The data is split. Multiple decision trees are combined in ensembles.

Surface tree languages and parallel derivation trees

NARCIS (Netherlands)

Engelfriet, Joost

1976-01-01

The surface tree languages obtained by top-down finite state transformation of monadic trees are exactly the frontier-preserving homomorphic images of sets of derivation trees of ETOL systems. The corresponding class of tree transformation languages is therefore equal to the class of ETOL languages.

Response of the soil microbial community and soil nutrient bioavailability to biomass harvesting and reserve tree retention in northern Minnesota aspen-dominated forests

Science.gov (United States)

Tera E. Lewandowski; Jodi A. Forrester; David J. Mladenoff; Anthony W. D' Amato; Brian J. Palik

2016-01-01

Intensive forest biomass harvesting, or the removal of harvesting slash (woody debris from tree branches and tops) for use as biofuel, has the potential to negatively affect the soil microbial community (SMC) due to loss of carbon and nutrient inputs from the slash, alteration of the soil microclimate, and increased nutrient leaching. These effects could result in...

Investigation on electrical tree propagation in polyethylene based on etching method

Directory of Open Access Journals (Sweden)

Zexiang Shi

2017-11-01

Full Text Available To investigate the characteristic of electrical tree propagation in semi-crystalline polymers, the low-density polyethylene (LDPE samples containing electrical trees are cut into slices by using ultramicrotome. Then the slice samples are etched by potassium permanganate etchant. Finally, the crystalline structure and the electrical tree propagation path in samples are observed by polarized light microscopy (PLM. According to the observation, the LDPE spherocrystal structure model is established on the basis of crystallization kinetics and morphology of polymers. And the electrical tree growth process in LDPE is discussed based on the free volume breakdown theory, the molecular chain relaxation theory, the electromechanical force theory, the thermal expansion effect and the space charge shielding effect.

Analysis of event tree with imprecise inputs by fuzzy set theory

International Nuclear Information System (INIS)

Ahn, Kwang Il; Chun, Moon Hyun

1990-01-01

Fuzzy set theory approach is proposed as a method to analyze event trees with imprecise or linguistic input variables such as 'likely' or 'improbable' instead of the numerical probability. In this paper, it is shown how the fuzzy set theory can be applied to the event tree analysis. The result of this study shows that the fuzzy set theory approach can be applied as an acceptable and effective tool for analysis of the event tree with fuzzy type of inputs. Comparisons of the fuzzy theory approach with the probabilistic approach of computing probabilities of final states of the event tree through subjective weighting factors and LHS technique show that the two approaches have common factors and give reasonable results

Phylogenetic affinity of tree shrews to Glires is attributed to fast evolution rate.

Science.gov (United States)

Lin, Jiannan; Chen, Guangfeng; Gu, Liang; Shen, Yuefeng; Zheng, Meizhu; Zheng, Weisheng; Hu, Xinjie; Zhang, Xiaobai; Qiu, Yu; Liu, Xiaoqing; Jiang, Cizhong

2014-02-01

Previous phylogenetic analyses have led to incongruent evolutionary relationships between tree shrews and other suborders of Euarchontoglires. What caused the incongruence remains elusive. In this study, we identified 6845 orthologous genes between seventeen placental mammals. Tree shrews and Primates were monophyletic in the phylogenetic trees derived from the first or/and second codon positions whereas tree shrews and Glires formed a monophyly in the trees derived from the third or all codon positions. The same topology was obtained in the phylogeny inference using the slowly and fast evolving genes, respectively. This incongruence was likely attributed to the fast substitution rate in tree shrews and Glires. Notably, sequence GC content only was not informative to resolve the controversial phylogenetic relationships between tree shrews, Glires, and Primates. Finally, estimation in the confidence of the tree selection strongly supported the phylogenetic affiliation of tree shrews to Primates as a monophyly. Copyright © 2013 Elsevier Inc. All rights reserved.

Comparative analysis of the effect of pretreating aspen wood with aqueous and aqueous-organic solutions of sulfuric and nitric acid on its reactivity during enzymatic hydrolysis

DEFF Research Database (Denmark)

Dotsenko, Gleb; Osipov, D. O.; Zorov, I. N.

2016-01-01

The effect of aspen wood pretreatment methods with the use of both aqueous solutions of sulfuric and nitric acids and aqueous-organic solutions (ethanol, butanol) of sulfuric acid (organosolv) on the limiting degree of conversion of this type of raw material into simple sugars during enzymatic...

Infinite dimensional spherical analysis and harmonic analysis for groups acting on homogeneous trees

DEFF Research Database (Denmark)

Axelgaard, Emil

In this thesis, we study groups of automorphisms for homogeneous trees of countable degree by using an inductive limit approach. The main focus is the thourough discussion of two Olshanski spherical pairs consisting of automorphism groups for a homogeneous tree and a homogeneous rooted tree, resp...... finite. Finally, we discuss conditionally positive definite functions on the groups and use the generalized Bochner-Godement theorem for Olshanski spherical pairs to prove Levy-Khinchine formulas for both of the considered pairs....

Utilization of fault tree analysis techniques in fire protection work

International Nuclear Information System (INIS)

Crass, E.R.

1986-01-01

This paper describes the development of a fault tree model for a typical pressurized water reactor (PWR), and the subsequent use of this model to perform a safe shutdown analysis and determine conformance with Section IIIG of 10 CFR 50, Appendix R. The paper describes the rationale for choosing this analytical tool, the development of the fault tree model, the analysis of the model using the PREP code, disposition of the results, and finally, application of the results to determine the need for plant modifications. It concludes with a review of the strengths and weaknesses of the use of Fault Tree Methodology for this application

ColorTree: a batch customization tool for phylogenic trees.

Science.gov (United States)

Chen, Wei-Hua; Lercher, Martin J

2009-07-31

Genome sequencing projects and comparative genomics studies typically aim to trace the evolutionary history of large gene sets, often requiring human inspection of hundreds of phylogenetic trees. If trees are checked for compatibility with an explicit null hypothesis (e.g., the monophyly of certain groups), this daunting task is greatly facilitated by an appropriate coloring scheme. In this note, we introduce ColorTree, a simple yet powerful batch customization tool for phylogenic trees. Based on pattern matching rules, ColorTree applies a set of customizations to an input tree file, e.g., coloring labels or branches. The customized trees are saved to an output file, which can then be viewed and further edited by Dendroscope (a freely available tree viewer). ColorTree runs on any Perl installation as a stand-alone command line tool, and its application can thus be easily automated. This way, hundreds of phylogenic trees can be customized for easy visual inspection in a matter of minutes. ColorTree allows efficient and flexible visual customization of large tree sets through the application of a user-supplied configuration file to multiple tree files.

Sequence Algebra, Sequence Decision Diagrams and Dynamic Fault Trees

International Nuclear Information System (INIS)

Rauzy, Antoine B.

2011-01-01

A large attention has been focused on the Dynamic Fault Trees in the past few years. By adding new gates to static (regular) Fault Trees, Dynamic Fault Trees aim to take into account dependencies among events. Merle et al. proposed recently an algebraic framework to give a formal interpretation to these gates. In this article, we extend Merle et al.'s work by adopting a slightly different perspective. We introduce Sequence Algebras that can be seen as Algebras of Basic Events, representing failures of non-repairable components. We show how to interpret Dynamic Fault Trees within this framework. Finally, we propose a new data structure to encode sets of sequences of Basic Events: Sequence Decision Diagrams. Sequence Decision Diagrams are very much inspired from Minato's Zero-Suppressed Binary Decision Diagrams. We show that all operations of Sequence Algebras can be performed on this data structure.

Assessing and Improving Student Understanding of Tree-Thinking

Science.gov (United States)

Kummer, Tyler A.

Evolution is the unifying theory of biology. The importance of understanding evolution by those who study the origins, diversification and diversity life cannot be overstated. Because of its importance, in addition to a scientific study of evolution, many researchers have spent time studying the acceptance and the teaching of evolution. Phylogenetic Systematics is the field of study developed to understand the evolutionary history of organisms, traits, and genes. Tree-thinking is the term by which we identify concepts related to the evolutionary history of organisms. It is vital that those who undertake a study of biology be able to understand and interpret what information these phylogenies are meant to convey. In this project, we evaluated the current impact a traditional study of biology has on the misconceptions students hold by assessing tree-thinking in freshman biology students to those nearing the end of their studies. We found that the impact of studying biology was varied with some misconceptions changing significantly while others persisted. Despite the importance of tree-thinking no appropriately developed concept inventory exists to measure student understanding of these important concepts. We developed a concept inventory capable of filling this important need and provide evidence to support its use among undergraduate students. Finally, we developed and modified activities as well as courses based on best practices to improve teaching and learning of tree-thinking and organismal diversity. We accomplished this by focusing on two key questions. First, how do we best introduce students to tree-thinking and second does tree-thinking as a course theme enhance student understanding of not only tree-thinking but also organismal diversity. We found important evidence suggesting that introducing students to tree-thinking via building evolutionary trees was less successful than introducing the concept via tree interpretation and may have in fact introduced or

Project whole tree utilization. Final summary report 1977

Energy Technology Data Exchange (ETDEWEB)

1977-01-01

The emerging shortage of wood fiber and the energy crisis in 1973 initiated this study to analyze the prospect of fuller utilization of the wood fiber resources. At a foreseen gross removal 75 million m/sup 3/sk, corresponding to around 62 million m/sup 3/ solid merchantable wood under bark, around 50 million m/sup 3/ solid volume, including needles, leaves, etc., is left in the forest, corresponding to around 30 million m/sup 3/ wood fiber. In general, these additional quantities are relatively more expensive than the normal wood, and of an inferior quality. Continued developments of machines and systems are urgent if the cost of harvesting is to be reduced. The ecological impact is varied. Stump extraction involves favorable soil preparation and diminishes the risk of insect infestations. Wood residues and stumps should not be removed on unfertile soils, poor in organic matter. On other forest soils it is unlikely that whole tree utilization will have any long term negative effect on soil fertility. However, needles, leaves, small branches, and roots should preferably be left since they are especially rich in nutrients. It was concluded that the short rotation energy forest will produce a fuel which is more expensive than available logging waste.

Tree Colors: Color Schemes for Tree-Structured Data.

Science.gov (United States)

Tennekes, Martijn; de Jonge, Edwin

2014-12-01

We present a method to map tree structures to colors from the Hue-Chroma-Luminance color model, which is known for its well balanced perceptual properties. The Tree Colors method can be tuned with several parameters, whose effect on the resulting color schemes is discussed in detail. We provide a free and open source implementation with sensible parameter defaults. Categorical data are very common in statistical graphics, and often these categories form a classification tree. We evaluate applying Tree Colors to tree structured data with a survey on a large group of users from a national statistical institute. Our user study suggests that Tree Colors are useful, not only for improving node-link diagrams, but also for unveiling tree structure in non-hierarchical visualizations.

Response of a forest ecotone to ionizing radiation. Progress report, October 15, 1976--October 14, 1977

International Nuclear Information System (INIS)

Murphy, P.G.; Sharitz, R.R.

1977-07-01

Compositional and structural characteristics of three forest types, including aspen dominated, maple-birch dominated, and an intervening ecotone, were studied before and after irradiation in northern Wisconsin. Irradiation occurred during the summer of 1972. By the summer of 1973 the density of viable tree seedlings at 10 m from the radiation source was substantially reduced in all three areas relative to the preirradiation densities of 1971. As of the summer of 1976, establishment of tree seedlings continued to be inhibited by the vigorous development of ground vegetation. At 20 m, the density of seedlings in the three areas increased during the period from 1971 to 1973 in response to the partially opened canopy. The overall density of seedlings of Populus tremuloides and Acer rubrum increased markedly in the three areas and P. tremuloides invaded some areas in which it had not been found prior to irradiation. By 1974 many of the seedlings at 20 m had reached the sapling size-class. Viable trees greater than 2.5 cm in dbh were eliminated at 10 m in all three areas by June of 1974 and were reduced in density at 20 m. At the present time it appears that recolonization of the 10 m irradiated zone by the original tree flora will be a very slow process. Leaf litter production was reduced by up to 92 percent at 10 m and 62 percent at 20 m during the period from 1971 to 1973 in the irradiated areas. In most respects the ecotone has shown properties and responses to radiation intermediate to those observed in the aspen and maple-birch areas. The rate and compositional characteristics of succession in the ecotone relative to aspen and maple-birch forest types is presently under study

TreePOD: Sensitivity-Aware Selection of Pareto-Optimal Decision Trees.

Science.gov (United States)

Muhlbacher, Thomas; Linhardt, Lorenz; Moller, Torsten; Piringer, Harald

2018-01-01

Balancing accuracy gains with other objectives such as interpretability is a key challenge when building decision trees. However, this process is difficult to automate because it involves know-how about the domain as well as the purpose of the model. This paper presents TreePOD, a new approach for sensitivity-aware model selection along trade-offs. TreePOD is based on exploring a large set of candidate trees generated by sampling the parameters of tree construction algorithms. Based on this set, visualizations of quantitative and qualitative tree aspects provide a comprehensive overview of possible tree characteristics. Along trade-offs between two objectives, TreePOD provides efficient selection guidance by focusing on Pareto-optimal tree candidates. TreePOD also conveys the sensitivities of tree characteristics on variations of selected parameters by extending the tree generation process with a full-factorial sampling. We demonstrate how TreePOD supports a variety of tasks involved in decision tree selection and describe its integration in a holistic workflow for building and selecting decision trees. For evaluation, we illustrate a case study for predicting critical power grid states, and we report qualitative feedback from domain experts in the energy sector. This feedback suggests that TreePOD enables users with and without statistical background a confident and efficient identification of suitable decision trees.

Synergistic Use of Citizen Science and Remote Sensing for Continental-Scale Measurements of Forest Tree Phenology

Directory of Open Access Journals (Sweden)

Andrew J. Elmore

2016-06-01

Full Text Available There is great potential value in linking geographically dispersed multitemporal observations collected by lay volunteers (or “citizen scientists” with remotely-sensed observations of plant phenology, which are recognized as useful indicators of climate change. However, challenges include a large mismatch in spatial scale and diverse sources of uncertainty in the two measurement types. These challenges must be overcome if the data from each source are to be compared and jointly used to understand spatial and temporal variation in phenology, or if remote observations are to be used to predict ground-based observations. We investigated the correlation between land surface phenology derived from Moderate Resolution Imaging Spectrometer (MODIS data and citizen scientists’ phenology observations from the USA National Phenology Network (NPN. The volunteer observations spanned 2004 to 2013 and represented 25 plant species and nine phenophases. We developed quality control procedures that removed observations outside of an a priori determined acceptable period and observations that were made more than 10 days after a preceding observation. We found that these two quality control steps improved the correlation between ground- and remote-observations, but the largest improvement was achieved when the analysis was restricted to forested MODIS pixels. These results demonstrate a high degree of correlation between the phenology of individual trees (particularly dominant forest trees such as quaking aspen, white oak, and American beech and the phenology of the surrounding forested landscape. These results provide helpful guidelines for the joint use of citizen scientists’ observations and remote sensing phenology in work aimed at understanding continental scale variation and temporal trends.

Two Trees: Migrating Fault Trees to Decision Trees for Real Time Fault Detection on International Space Station

Science.gov (United States)

Lee, Charles; Alena, Richard L.; Robinson, Peter

2004-01-01

We started from ISS fault trees example to migrate to decision trees, presented a method to convert fault trees to decision trees. The method shows that the visualizations of root cause of fault are easier and the tree manipulating becomes more programmatic via available decision tree programs. The visualization of decision trees for the diagnostic shows a format of straight forward and easy understands. For ISS real time fault diagnostic, the status of the systems could be shown by mining the signals through the trees and see where it stops at. The other advantage to use decision trees is that the trees can learn the fault patterns and predict the future fault from the historic data. The learning is not only on the static data sets but also can be online, through accumulating the real time data sets, the decision trees can gain and store faults patterns in the trees and recognize them when they come.

Application of Infrared and Raman Spectroscopy for the Identification of Disease Resistant Trees.

Science.gov (United States)

Conrad, Anna O; Bonello, Pierluigi

2015-01-01

New approaches for identifying disease resistant trees are needed as the incidence of diseases caused by non-native and invasive pathogens increases. These approaches must be rapid, reliable, cost-effective, and should have the potential to be adapted for high-throughput screening or phenotyping. Within the context of trees and tree diseases, we summarize vibrational spectroscopic and chemometric methods that have been used to distinguish between groups of trees which vary in disease susceptibility or other important characteristics based on chemical fingerprint data. We also provide specific examples from the literature of where these approaches have been used successfully. Finally, we discuss future application of these approaches for wide-scale screening and phenotyping efforts aimed at identifying disease resistant trees and managing forest diseases.

The value of information in conservation planning: Selecting retention trees for lichen conservation

Science.gov (United States)

Karin Perhans; Robert G. Haight; Lena Gustafsson

2014-01-01

Conservation planning studies at small scales such as forest stands and below are uncommon. However, for retention forestry, developed during the last two decades and with current wide and increasing application in boreal and temperate regions, the need for cost-effective selection of individual trees is evident. In retention forestry certain trees are left at final...

Woody tissue analysis using an element ratio technique (DRIS)

Science.gov (United States)

Kurt H. Riitters; L.F. Ohmann; D.F. Grigal

1991-01-01

The diagnosis and recommendation integrated system (DRIS) was used to describe the variation of 12 elements in woody tree tissue and balsam fir (Abies balsamae (L.) Mill.), sugar maple (Acer saccharum Marsh.), jack pine (Pinus banksiana Lamb.), red pine (Pinus resinosa alt.), and aspen (

Tree Classification with Fused Mobile Laser Scanning and Hyperspectral Data

Science.gov (United States)

Puttonen, Eetu; Jaakkola, Anttoni; Litkey, Paula; Hyyppä, Juha

2011-01-01

Mobile Laser Scanning data were collected simultaneously with hyperspectral data using the Finnish Geodetic Institute Sensei system. The data were tested for tree species classification. The test area was an urban garden in the City of Espoo, Finland. Point clouds representing 168 individual tree specimens of 23 tree species were determined manually. The classification of the trees was done using first only the spatial data from point clouds, then with only the spectral data obtained with a spectrometer, and finally with the combined spatial and hyperspectral data from both sensors. Two classification tests were performed: the separation of coniferous and deciduous trees, and the identification of individual tree species. All determined tree specimens were used in distinguishing coniferous and deciduous trees. A subset of 133 trees and 10 tree species was used in the tree species classification. The best classification results for the fused data were 95.8% for the separation of the coniferous and deciduous classes. The best overall tree species classification succeeded with 83.5% accuracy for the best tested fused data feature combination. The respective results for paired structural features derived from the laser point cloud were 90.5% for the separation of the coniferous and deciduous classes and 65.4% for the species classification. Classification accuracies with paired hyperspectral reflectance value data were 90.5% for the separation of coniferous and deciduous classes and 62.4% for different species. The results are among the first of their kind and they show that mobile collected fused data outperformed single-sensor data in both classification tests and by a significant margin. PMID:22163894

DECISION TREE CLASSIFIERS FOR STAR/GALAXY SEPARATION

International Nuclear Information System (INIS)

Vasconcellos, E. C.; Ruiz, R. S. R.; De Carvalho, R. R.; Capelato, H. V.; Gal, R. R.; LaBarbera, F. L.; Frago Campos Velho, H.; Trevisan, M.

2011-01-01

We study the star/galaxy classification efficiency of 13 different decision tree algorithms applied to photometric objects in the Sloan Digital Sky Survey Data Release Seven (SDSS-DR7). Each algorithm is defined by a set of parameters which, when varied, produce different final classification trees. We extensively explore the parameter space of each algorithm, using the set of 884,126 SDSS objects with spectroscopic data as the training set. The efficiency of star-galaxy separation is measured using the completeness function. We find that the Functional Tree algorithm (FT) yields the best results as measured by the mean completeness in two magnitude intervals: 14 ≤ r ≤ 21 (85.2%) and r ≥ 19 (82.1%). We compare the performance of the tree generated with the optimal FT configuration to the classifications provided by the SDSS parametric classifier, 2DPHOT, and Ball et al. We find that our FT classifier is comparable to or better in completeness over the full magnitude range 15 ≤ r ≤ 21, with much lower contamination than all but the Ball et al. classifier. At the faintest magnitudes (r > 19), our classifier is the only one that maintains high completeness (>80%) while simultaneously achieving low contamination (∼2.5%). We also examine the SDSS parametric classifier (psfMag - modelMag) to see if the dividing line between stars and galaxies can be adjusted to improve the classifier. We find that currently stars in close pairs are often misclassified as galaxies, and suggest a new cut to improve the classifier. Finally, we apply our FT classifier to separate stars from galaxies in the full set of 69,545,326 SDSS photometric objects in the magnitude range 14 ≤ r ≤ 21.

Tree Nut Allergies

Science.gov (United States)

... Blog Vision Awards Common Allergens Tree Nut Allergy Tree Nut Allergy Learn about tree nut allergy, how ... a Tree Nut Label card . Allergic Reactions to Tree Nuts Tree nuts can cause a severe and ...

Molecular fundamentals of nitrogen uptake and transport in trees.

Science.gov (United States)

Castro-Rodríguez, Vanessa; Cañas, Rafael A; de la Torre, Fernando N; Pascual, Ma Belén; Avila, Concepción; Cánovas, Francisco M

2017-05-01

Nitrogen (N) is frequently a limiting factor for tree growth and development. Because N availability is extremely low in forest soils, trees have evolved mechanisms to acquire and transport this essential nutrient along with biotic interactions to guarantee its strict economy. Here we review recent advances in the molecular basis of tree N nutrition. The molecular characteristics, regulation, and biological significance of membrane proteins involved in the uptake and transport of N are addressed. The regulation of N uptake and transport in mycorrhized roots and transcriptome-wide studies of N nutrition are also outlined. Finally, several areas of future research are suggested. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Big trees, old trees, and growth factor tables

Science.gov (United States)

Kevin T. Smith

2018-01-01

The potential for a tree to reach a great size and to live a long life frequently captures the public's imagination. Sometimes the desire to know the age of an impressively large tree is simple curiosity. For others, the date-of-tree establishment can make a big diff erence for management, particularly for trees at historic sites or those mentioned in property...

A Suffix Tree Or Not a Suffix Tree?

DEFF Research Database (Denmark)

Starikovskaya, Tatiana; Vildhøj, Hjalte Wedel

2015-01-01

In this paper we study the structure of suffix trees. Given an unlabeled tree r on n nodes and suffix links of its internal nodes, we ask the question “Is r a suffix tree?”, i.e., is there a string S whose suffix tree has the same topological structure as r? We place no restrictions on S, in part...

Bibliography on Cold Regions Science and Technology, Volume 46, Part 1, 1992

Science.gov (United States)

1992-01-01

analysis, snose cover is depleted and a bhoswl-shaped depression (a tree Ecology, Nutrient cycle. Bitmass.46-3969 well) forms. Around aspen and birch...ibscrsatuons ori heteroigenrerus asterlee hysis an miromehanis: arevew o selctedItow and siome attcmptS 1 tomidel percirlattirn in (%o moirds Ice hyscs

Report on AECB consultative document C-70: The use of fault trees in licensing submissions

International Nuclear Information System (INIS)

1984-01-01

The Atomic Energy Control Board (AECB) has issued Consultative Document C-70, 'The Use of Fault Trees in Licensing Submissions', for public comment. The Advisory Committee on Nuclear Safety (ACNS) has examined this document and ACNS members have met with AECB staff and representatives of the nuclear industry to discuss it. The ACNS presents its comments and recommendations in this report. The consultative document defines a fault tree as a hierarchically-structured graphical representation of system failures and their potential causes. The document then states certain basic characteristics or attributes which fault trees should possess, and certain conditions affecting the use of fault trees. It defines fault tree fundamentals, sets criteria for the application of fault trees to systems and defines ground rules for a fault tree format. Finally, in two appendices, it includes specific rules for fault tree symbols and fault tree description files for computer use. The appendices are referred to in the text as 'acceptable' standards or methods

Measuring urban tree loss dynamics across residential landscapes.

Science.gov (United States)

Ossola, Alessandro; Hopton, Matthew E

2018-01-15

The spatial arrangement of urban vegetation depends on urban morphology and socio-economic settings. Urban vegetation changes over time because of human management. Urban trees are removed due to hazard prevention or aesthetic preferences. Previous research attributed tree loss to decreases in canopy cover. However, this provides little information about location and structural characteristics of trees lost, as well as environmental and social factors affecting tree loss dynamics. This is particularly relevant in residential landscapes where access to residential parcels for field surveys is limited. We tested whether multi-temporal airborne LiDAR and multi-spectral imagery collected at a 5-year interval can be used to investigate urban tree loss dynamics across residential landscapes in Denver, CO and Milwaukee, WI, covering 400,705 residential parcels in 444 census tracts. Position and stem height of trees lost were extracted from canopy height models calculated as the difference between final (year 5) and initial (year 0) vegetation height derived from LiDAR. Multivariate regression models were used to predict number and height of tree stems lost in residential parcels in each census tract based on urban morphological and socio-economic variables. A total of 28,427 stems were lost from residential parcels in Denver and Milwaukee over 5years. Overall, 7% of residential parcels lost one stem, averaging 90.87 stems per km 2 . Average stem height was 10.16m, though trees lost in Denver were taller compared to Milwaukee. The number of stems lost was higher in neighborhoods with higher canopy cover and developed before the 1970s. However, socio-economic characteristics had little effect on tree loss dynamics. The study provides a simple method for measuring urban tree loss dynamics within and across entire cities, and represents a further step toward high resolution assessments of the three-dimensional change of urban vegetation at large spatial scales. Published by

Genome sequence of the olive tree, Olea europaea.

Science.gov (United States)

Cruz, Fernando; Julca, Irene; Gómez-Garrido, Jèssica; Loska, Damian; Marcet-Houben, Marina; Cano, Emilio; Galán, Beatriz; Frias, Leonor; Ribeca, Paolo; Derdak, Sophia; Gut, Marta; Sánchez-Fernández, Manuel; García, Jose Luis; Gut, Ivo G; Vargas, Pablo; Alioto, Tyler S; Gabaldón, Toni

2016-06-27

The Mediterranean olive tree (Olea europaea subsp. europaea) was one of the first trees to be domesticated and is currently of major agricultural importance in the Mediterranean region as the source of olive oil. The molecular bases underlying the phenotypic differences among domesticated cultivars, or between domesticated olive trees and their wild relatives, remain poorly understood. Both wild and cultivated olive trees have 46 chromosomes (2n). A total of 543 Gb of raw DNA sequence from whole genome shotgun sequencing, and a fosmid library containing 155,000 clones from a 1,000+ year-old olive tree (cv. Farga) were generated by Illumina sequencing using different combinations of mate-pair and pair-end libraries. Assembly gave a final genome with a scaffold N50 of 443 kb, and a total length of 1.31 Gb, which represents 95 % of the estimated genome length (1.38 Gb). In addition, the associated fungus Aureobasidium pullulans was partially sequenced. Genome annotation, assisted by RNA sequencing from leaf, root, and fruit tissues at various stages, resulted in 56,349 unique protein coding genes, suggesting recent genomic expansion. Genome completeness, as estimated using the CEGMA pipeline, reached 98.79 %. The assembled draft genome of O. europaea will provide a valuable resource for the study of the evolution and domestication processes of this important tree, and allow determination of the genetic bases of key phenotypic traits. Moreover, it will enhance breeding programs and the formation of new varieties.

Tree-growth analyses to estimate tree species' drought tolerance

NARCIS (Netherlands)

Eilmann, B.; Rigling, A.

2012-01-01

Climate change is challenging forestry management and practices. Among other things, tree species with the ability to cope with more extreme climate conditions have to be identified. However, while environmental factors may severely limit tree growth or even cause tree death, assessing a tree

Dendrochronological Investigations of Valonia Oak Trees in Western Greece

Directory of Open Access Journals (Sweden)

Andreas Papadopoulos

2016-06-01

Full Text Available Background and Purpose: Valonia oak (Quercus ithaburensis subsp. macrolepis (Kotschy Hedge & Yalt. is an east Mediterranean endemic, xerothermic and deciduous tree of particular interest in forestry. There has been a growing demand lately to include the species in reforestations in Greece which also increased the interest to investigate its response to climate change. The main purpose of this research is to study valonia oak from a dendrochronological – dendroclimatological point of view within its Mediterranean distribution range. Materials and Methods: Sampling took place in characteristic valonia oak stands where cross sections or tree-cores were taken from 40 trees. The cross sections and the tree-cores were prepared and cross-dated using standard dendrochronological methods and tree-ring widths were measured to the nearest 0.001 mm using the Windendro software program. The ARSTAN program was used to standardize the tree-ring data and to calculate dendrochronological statistical parameters. The inter-annual variability of tree-ring width and the radial growth trend were examined. Finally, tree-ring widths to climate relationships were calculated by orthogonal regression in combination with the bootstrap procedure using master residual chronology and monthly precipitation, temperature data and scPDSI drought index, from October of the n-1 year up to November of the n year. Results: The master chronology of valonia oak trees in Western Greece reaches 365 years, with an average ring width of 0.89 mm and with mean sensitivity being 0.21. The variation of the tree-ring widths indicates the influence of climate and human intervention in the past. Tree-ring to climate relationships show that valonia oak growth is positively affected by precipitations in January and March and by drought reduction during June and July. Conclusions: Valonia oak in Western Greece is a species of great interest for dendrochronological and dendroclimatological studies

Distributed Merge Trees

Energy Technology Data Exchange (ETDEWEB)

Morozov, Dmitriy; Weber, Gunther

2013-01-08

Improved simulations and sensors are producing datasets whose increasing complexity exhausts our ability to visualize and comprehend them directly. To cope with this problem, we can detect and extract significant features in the data and use them as the basis for subsequent analysis. Topological methods are valuable in this context because they provide robust and general feature definitions. As the growth of serial computational power has stalled, data analysis is becoming increasingly dependent on massively parallel machines. To satisfy the computational demand created by complex datasets, algorithms need to effectively utilize these computer architectures. The main strength of topological methods, their emphasis on global information, turns into an obstacle during parallelization. We present two approaches to alleviate this problem. We develop a distributed representation of the merge tree that avoids computing the global tree on a single processor and lets us parallelize subsequent queries. To account for the increasing number of cores per processor, we develop a new data structure that lets us take advantage of multiple shared-memory cores to parallelize the work on a single node. Finally, we present experiments that illustrate the strengths of our approach as well as help identify future challenges.

TreeNetViz: revealing patterns of networks over tree structures.

Science.gov (United States)

Gou, Liang; Zhang, Xiaolong Luke

2011-12-01

Network data often contain important attributes from various dimensions such as social affiliations and areas of expertise in a social network. If such attributes exhibit a tree structure, visualizing a compound graph consisting of tree and network structures becomes complicated. How to visually reveal patterns of a network over a tree has not been fully studied. In this paper, we propose a compound graph model, TreeNet, to support visualization and analysis of a network at multiple levels of aggregation over a tree. We also present a visualization design, TreeNetViz, to offer the multiscale and cross-scale exploration and interaction of a TreeNet graph. TreeNetViz uses a Radial, Space-Filling (RSF) visualization to represent the tree structure, a circle layout with novel optimization to show aggregated networks derived from TreeNet, and an edge bundling technique to reduce visual complexity. Our circular layout algorithm reduces both total edge-crossings and edge length and also considers hierarchical structure constraints and edge weight in a TreeNet graph. These experiments illustrate that the algorithm can reduce visual cluttering in TreeNet graphs. Our case study also shows that TreeNetViz has the potential to support the analysis of a compound graph by revealing multiscale and cross-scale network patterns. © 2011 IEEE

Electrical treeing behaviors in silicone rubber under an impulse voltage considering high temperature

Science.gov (United States)

Yunxiao, ZHANG; Yuanxiang, ZHOU; Ling, ZHANG; Zhen, LIN; Jie, LIU; Zhongliu, ZHOU

2018-05-01

In this paper, work was conducted to reveal electrical tree behaviors (initiation and propagation) of silicone rubber (SIR) under an impulse voltage with high temperature. Impulse frequencies ranging from 10 Hz to 1 kHz were applied and the temperature was controlled between 30 °C and 90 °C. Experimental results show that tree initiation voltage decreases with increasing pulse frequency, and the descending amplitude is different in different frequency bands. As the pulse frequency increases, more frequent partial discharges occur in the channel, increasing the tree growth rate and the final shape intensity. As for temperature, the initiation voltage decreases and the tree shape becomes denser as the temperature gets higher. Based on differential scanning calorimetry results, we believe that partial segment relaxation of SIR at high temperature leads to a decrease in the initiation voltage. However, the tree growth rate decreases with increasing temperature. Carbonization deposition in the channel under high temperature was observed under microscope and proven by Raman analysis. Different tree growth models considering tree channel characteristics are proposed. It is believed that increasing the conductivity in the tree channel restrains the partial discharge, holding back the tree growth at high temperature.

TREE SELECTING AND TREE RING MEASURING IN DENDROCHRONOLOGICAL INVESTIGATIONS

Directory of Open Access Journals (Sweden)

Sefa Akbulut

2004-04-01

Full Text Available Dendrochronology is a method of dating which makes use of the annual nature of tree growth. Dendrochronology may be divided into a number of subfields, each of which covers one or more aspects of the use of tree ring data: dendroclimatology, dendrogeomorphology, dendrohydrology, dendroecology, dendroarchaelogy, and dendrogylaciology. Basic of all form the analysis of the tree rings. The wood or tree rings can aid to dating past events about climatology, ecology, geology, hydrology. Dendrochronological studies are conducted either on increment cores or on discs. It may be seen abnormalities on tree rings during the measurement like that false rings, missing rings, reaction wood. Like that situation, increment cores must be extracted from four different sides of each tree and be studied as more as on tree.

Aspen Plus® and economic modeling of equine waste utilization for localized hot water heating via fast pyrolysis.

Science.gov (United States)

Hammer, Nicole L; Boateng, Akwasi A; Mullen, Charles A; Wheeler, M Clayton

2013-10-15

Aspen Plus(®) based simulation models have been developed to design a pyrolysis process for on-site production and utilization of pyrolysis oil from equine waste at the Equine Rehabilitation Center at Morrisville State College (MSC). The results indicate that utilization of all the available waste from the site's 41 horses requires a 6 oven dry metric ton per day (ODMTPD) pyrolysis system but it will require a 15 ODMTPD system for waste generated by an additional 150 horses at the expanded area including the College and its vicinity. For this a dual fluidized bed combustion reduction integrated pyrolysis system (CRIPS) developed at USDA's Agricultural Research Service (ARS) was identified as the technology of choice for pyrolysis oil production. The Aspen Plus(®) model was further used to consider the combustion of the produced pyrolysis oil (bio-oil) in the existing boilers that generate hot water for space heating at the Equine Center. The model results show the potential for both the equine facility and the College to displace diesel fuel (fossil) with renewable pyrolysis oil and alleviate a costly waste disposal problem. We predict that all the heat required to operate the pyrolyzer could be supplied by non-condensable gas and about 40% of the biochar co-produced with bio-oil. Techno-economic Analysis shows neither design is economical at current market conditions; however the 15 ODMTPD CRIPS design would break even when diesel prices reach $11.40/gal. This can be further improved to $7.50/gal if the design capacity is maintained at 6 ODMTPD but operated at 4950 h per annum. Published by Elsevier Ltd.

Visualizing Individual Tree Differences in Tree-Ring Studies

Directory of Open Access Journals (Sweden)

Mario Trouillier

2018-04-01

Full Text Available Averaging tree-ring measurements from multiple individuals is one of the most common procedures in dendrochronology. It serves to filter out noise from individual differences between trees, such as competition, height, and micro-site effects, which ideally results in a site chronology sensitive to regional scale factors such as climate. However, the climate sensitivity of individual trees can be modulated by factors like competition, height, and nitrogen deposition, calling attention to whether average chronologies adequately assess climatic growth-control. In this study, we demonstrate four simple but effective methods to visually assess differences between individual trees. Using individual tree climate-correlations we: (1 employed jitter plots with superimposed metadata to assess potential causes for these differences; (2 plotted the frequency distributions of climate correlations over time as heat maps; (3 mapped the spatial distribution of climate sensitivity over time to assess spatio-temporal dynamics; and (4 used t-distributed Stochastic Neighborhood Embedding (t-SNE to assess which trees were generally more similar in terms of their tree-ring pattern and their correlation with climate variables. This suite of exploratory methods can indicate if individuals in tree-ring datasets respond differently to climate variability, and therefore, should not solely be explored with climate correlations of the mean population chronology.

Isotope studies to determine dry deposition of sulfate to deciduous and coniferous trees: Final draft

International Nuclear Information System (INIS)

Garten, C.T. Jr.

1988-01-01

Experiments have been conducted at two locations near Oak Ridge, Tennessee, with radioactive 35 S (87 day half-life) to examine the cycling behavior of sulfur in yellow poplar (Liriodendron tulipifera), red maple (Acer rubrum), and loblolly pine (Pinus taeda) trees. Some findings pertain to methods development for estimating dry deposition of sulfur to forest canopies and the magnitude of sulfur emissions from natural sources (Task II). We will determine through field studies, the internal cycling, storage, and biogenic emission of sulfur, as traced by 35 SO 4 2- , in environments impacted by atmospheric sulfate deposition; and will determine through isotope dilution studies, the contribution of foliar leaching and dry deposition to net throughfall (NTF) sulfate concentrations beneath deciduous and coniferous trees in such environments. 3 refs., 2 figs., 1 tab

Fault tree handbook

International Nuclear Information System (INIS)

Haasl, D.F.; Roberts, N.H.; Vesely, W.E.; Goldberg, F.F.

1981-01-01

This handbook describes a methodology for reliability analysis of complex systems such as those which comprise the engineered safety features of nuclear power generating stations. After an initial overview of the available system analysis approaches, the handbook focuses on a description of the deductive method known as fault tree analysis. The following aspects of fault tree analysis are covered: basic concepts for fault tree analysis; basic elements of a fault tree; fault tree construction; probability, statistics, and Boolean algebra for the fault tree analyst; qualitative and quantitative fault tree evaluation techniques; and computer codes for fault tree evaluation. Also discussed are several example problems illustrating the basic concepts of fault tree construction and evaluation

MARRT: Medial Axis biased rapidly-exploring random trees

KAUST Repository

Denny, Jory

2014-05-01

© 2014 IEEE. Motion planning is a difficult and widely studied problem in robotics. Current research aims not only to find feasible paths, but to ensure paths have certain properties, e.g., shortest or safest paths. This is difficult for current state-of-the-art sampling-based techniques as they typically focus on simply finding any path. Despite this difficulty, sampling-based techniques have shown great success in planning for a wide range of applications. Among such planners, Rapidly-Exploring Random Trees (RRTs) search the planning space by biasing exploration toward unexplored regions. This paper introduces a novel RRT variant, Medial Axis RRT (MARRT), which biases tree exploration to the medial axis of free space by pushing all configurations from expansion steps towards the medial axis. We prove that this biasing increases the tree\\'s clearance from obstacles. Improving obstacle clearance is useful where path safety is important, e.g., path planning for robots performing tasks in close proximity to the elderly. Finally, we experimentally analyze MARRT, emphasizing its ability to effectively map difficult passages while increasing obstacle clearance, and compare it to contemporary RRT techniques.

Variation in Linked Selection and Recombination Drive Genomic Divergence during Allopatric Speciation of European and American Aspens.

Science.gov (United States)

Wang, Jing; Street, Nathaniel R; Scofield, Douglas G; Ingvarsson, Pär K

2016-07-01

Despite the global economic and ecological importance of forest trees, the genomic basis of differential adaptation and speciation in tree species is still poorly understood. Populus tremula and Populus tremuloides are two of the most widespread tree species in the Northern Hemisphere. Using whole-genome re-sequencing data of 24 P. tremula and 22 P. tremuloides individuals, we find that the two species diverged ∼2.2-3.1 million years ago, coinciding with the severing of the Bering land bridge and the onset of dramatic climatic oscillations during the Pleistocene. Both species have experienced substantial population expansions following long-term declines after species divergence. We detect widespread and heterogeneous genomic differentiation between species, and in accordance with the expectation of allopatric speciation, coalescent simulations suggest that neutral evolutionary processes can account for most of the observed patterns of genetic differentiation. However, there is an excess of regions exhibiting extreme differentiation relative to those expected under demographic simulations, which is indicative of the action of natural selection. Overall genetic differentiation is negatively associated with recombination rate in both species, providing strong support for a role of linked selection in generating the heterogeneous genomic landscape of differentiation between species. Finally, we identify a number of candidate regions and genes that may have been subject to positive and/or balancing selection during the speciation process. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Dimension yields from short logs of low-quality hardwood trees.

Science.gov (United States)

Howard N. Rosen; Harold A. Stewart; David J. Polak

1980-01-01

Charts are presented for determining yields of 4/4 dimension cuttings from short hardwood logs of aspen, soft maple, black cherry, yellow-poplar, and black walnut for several cutting grades and bolt sizes. Cost comparisons of short log and standard grade mixes show sizes. Cost comparisons of short log and standard grade mixes show the estimated least expensive...

Weathering the storm: how lodgepole pine trees survive mountain pine beetle outbreaks.

Science.gov (United States)

Erbilgin, Nadir; Cale, Jonathan A; Hussain, Altaf; Ishangulyyeva, Guncha; Klutsch, Jennifer G; Najar, Ahmed; Zhao, Shiyang

2017-06-01

Recent mountain pine beetle outbreaks in western North America killed millions of lodgepole pine trees, leaving few survivors. However, the mechanism underlying the ability of trees to survive bark beetle outbreaks is unknown, but likely involve phytochemicals such as monoterpenes and fatty acids that can drive beetle aggregation and colonization on their hosts. Thus, we conducted a field survey of beetle-resistant lodgepole pine (Pinus contorta) trees to retrospectively deduce whether these phytochemicals underlie their survival by comparing their chemistry to that of non-attacked trees in the same stands. We also compared beetle attack characteristics between resistant and beetle-killed trees. Beetle-killed trees had more beetle attacks and longer ovipositional galleries than resistant trees, which also lacked the larval establishment found in beetle-killed trees. Resistant trees contained high amounts of toxic and attraction-inhibitive compounds and low amounts of pheromone-precursor and synergist compounds. During beetle host aggregation and colonization, these compounds likely served three critical roles in tree survival. First, low amounts of pheromone-precursor (α-pinene) and synergist (mycrene, terpinolene) compounds reduced or prevented beetles from attracting conspecifics to residual trees. Second, high amounts of 4-allyanisole further inhibited beetle attraction to its pheromone. Finally, high amounts of toxic limonene, 3-carene, 4-allyanisole, α-linolenic acid, and linoleic acid inhibited beetle gallery establishment and oviposition. We conclude that the variation of chemotypic expression of local plant populations can have profound ecological consequences including survival during insect outbreaks.

Response trees and expert systems for nuclear reactor operations

International Nuclear Information System (INIS)

Nelson, W.R.

1984-02-01

The United States Nuclear Regulatory Commission is sponsoring a project performed by EG and G Idaho, Inc., at the Idaho National Engineering Laboratory (INEL) to evaluate different display concepts for use in nuclear reactor control rooms. Included in this project is the evaluation of the response tree computer based decision aid and its associated displays. This report serves as an overview of the response tree methodology and how it has been implemented as a computer based decision aid utilizing color graphic displays. A qualitative assessment of the applicability of the response tree aid in the reactor control room is also made. Experience gained in evaluating the response tree aid is generalized to address a larger category of computer aids, those known as knowledge based expert systems. General characteristics of expert systems are discussed, as well as examples of their application in other domains. A survey of ongoing work on expert systems in the nuclear industry is presented, and an assessment of their potential applicability is made. Finally, recommendations for the design and evaluation of computer based decision aids are presented

A Domain-Specific Languane for Regular Sets of Strings and Trees

DEFF Research Database (Denmark)

Schwartzbach, Michael Ignatieff; Klarlund, Nils

1999-01-01

We propose a new high-level progr amming notation, called FIDO, that we have designed to concisely express regular sets of strings or trees. In particular, it can be viewed as a domain-specific language for the expression of finite-state automata on large alphabets (of sometimes astronomical size......, called the Monadic Second-order Logic (M2L) on trees. FIDO is translated first into pure M2L via suitable encodings, and finally into finite-state automata through the MONA tool....

A Hybrid Shared-Memory Parallel Max-Tree Algorithm for Extreme Dynamic-Range Images.

Science.gov (United States)

Moschini, Ugo; Meijster, Arnold; Wilkinson, Michael H F

2018-03-01

Max-trees, or component trees, are graph structures that represent the connected components of an image in a hierarchical way. Nowadays, many application fields rely on images with high-dynamic range or floating point values. Efficient sequential algorithms exist to build trees and compute attributes for images of any bit depth. However, we show that the current parallel algorithms perform poorly already with integers at bit depths higher than 16 bits per pixel. We propose a parallel method combining the two worlds of flooding and merging max-tree algorithms. First, a pilot max-tree of a quantized version of the image is built in parallel using a flooding method. Later, this structure is used in a parallel leaf-to-root approach to compute efficiently the final max-tree and to drive the merging of the sub-trees computed by the threads. We present an analysis of the performance both on simulated and actual 2D images and 3D volumes. Execution times are about better than the fastest sequential algorithm and speed-up goes up to on 64 threads.

Priority effects of early successional insects influence late successional fungi in dead wood.

Science.gov (United States)

Jacobsen, Rannveig Margrete; Birkemoe, Tone; Sverdrup-Thygeson, Anne

2015-11-01

Community assembly is an integral process in all ecosystems, producing patterns of species distributions, biodiversity, and ecosystem functioning. Environmental filters and colonization history govern the assembly process, but their relative importance varies depending on the study system. Dead wood decomposition is a slow process, allowing decomposer communities to develop within a slowly changing substrate for decades. Despite this, there are few long-term studies of priority effects from colonization history in this ecosystem. In this study, we investigate the importance of insects in early succession of dead wood on the fungal community present one decade later. Sixty aspen trees were killed in two study landscapes, each tree producing one aspen high stump and log. Insects were sampled with flight interception traps during the first 4 years after tree death, and fungal fruiting bodies were registered in year twelve. We found positive priority effects of two fungivorous beetles, the sap beetle Glischrochilus quadripunctatus and the round fungus beetle Agathidium nigripenne, on the Artist's bracket (Ganoderma applanatum) and a positive priority effect of wood-boring beetles on the ascomycete Yellow fairy cup (Bisporella citrina). The Aspen bracket (Phellinus tremulae) did not respond to insects in early succession of the dead wood. Our results suggest that early successional insects can have significant, long-lasting effects on the late successional fungal community in dead wood. Also, the effect can be specific, with one fungus species depending on one or a few fungivorous beetle species. This has implications for decomposition and biodiversity in dead wood, as loss of early colonizing beetles may also affect the successional pathways they seem to initiate.

Contribution of competition for light to within-species variability in stomatal conductance

Science.gov (United States)

Loranty, Michael M.; Mackay, D. Scott; Ewers, Brent E.; Traver, Elizabeth; Kruger, Eric L.

2010-05-01

Sap flux (JS) measurements were collected across two stands dominated by either trembling aspen or sugar maple in northern Wisconsin. Observed canopy transpiration (EC-obs) values derived from JS were used to parameterize the Terrestrial Regional Ecosystem Exchange Simulator ecosystem model. Modeled values of stomatal conductance (GS) were used to determine reference stomatal conductance (GSref), a proxy for GS that removes the effects of temporal responses to vapor pressure deficit (D) on spatial patterns of GS. Values of GSref were compared to observations of soil moisture, several physiological variables, and a competition index (CI) derived from a stand inventory, to determine the underlying cause of observed variability. Considerable variability in GSref between individual trees was found, with values ranging from 20 to 200 mmol m-2 s-1 and 20 to 100 mmol m-2 s-1 at the aspen and maple stands, respectively. Model-derived values of GSref and a sensitivity to D parameter (m) showed good agreement with a known empirical relationship for both stands. At both sites, GSref did not vary with topographic position, as indicated by surface soil moisture. No relationships were observed between GSref and tree height (HT), and a weak correlation with sapwood area (AS) was only significant for aspen. Significant nonlinear inverse relationships between GSref and CI were observed at both stands. Simulations with uniform reductions in incident photosynthetically active radiation (Q0) resulted in better agreement between observed and simulated EC. Our results suggest a link between photosynthesis and plant hydraulics whereby individual trees subject to photosynthetic limitation as a result of competitive shading exhibit a dynamic stomatal response resulting in a more conservative strategy for managing hydrologic resources.

Modular tree automata

DEFF Research Database (Denmark)

Bahr, Patrick

2012-01-01

Tree automata are traditionally used to study properties of tree languages and tree transformations. In this paper, we consider tree automata as the basis for modular and extensible recursion schemes. We show, using well-known techniques, how to derive from standard tree automata highly modular...

Rate of tree carbon accumulation increases continuously with tree size.

Science.gov (United States)

Stephenson, N L; Das, A J; Condit, R; Russo, S E; Baker, P J; Beckman, N G; Coomes, D A; Lines, E R; Morris, W K; Rüger, N; Alvarez, E; Blundo, C; Bunyavejchewin, S; Chuyong, G; Davies, S J; Duque, A; Ewango, C N; Flores, O; Franklin, J F; Grau, H R; Hao, Z; Harmon, M E; Hubbell, S P; Kenfack, D; Lin, Y; Makana, J-R; Malizia, A; Malizia, L R; Pabst, R J; Pongpattananurak, N; Su, S-H; Sun, I-F; Tan, S; Thomas, D; van Mantgem, P J; Wang, X; Wiser, S K; Zavala, M A

2014-03-06

Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

Novel information theory-based measures for quantifying incongruence among phylogenetic trees.

Science.gov (United States)

Salichos, Leonidas; Stamatakis, Alexandros; Rokas, Antonis

2014-05-01

Phylogenies inferred from different data matrices often conflict with each other necessitating the development of measures that quantify this incongruence. Here, we introduce novel measures that use information theory to quantify the degree of conflict or incongruence among all nontrivial bipartitions present in a set of trees. The first measure, internode certainty (IC), calculates the degree of certainty for a given internode by considering the frequency of the bipartition defined by the internode (internal branch) in a given set of trees jointly with that of the most prevalent conflicting bipartition in the same tree set. The second measure, IC All (ICA), calculates the degree of certainty for a given internode by considering the frequency of the bipartition defined by the internode in a given set of trees in conjunction with that of all conflicting bipartitions in the same underlying tree set. Finally, the tree certainty (TC) and TC All (TCA) measures are the sum of IC and ICA values across all internodes of a phylogeny, respectively. IC, ICA, TC, and TCA can be calculated from different types of data that contain nontrivial bipartitions, including from bootstrap replicate trees to gene trees or individual characters. Given a set of phylogenetic trees, the IC and ICA values of a given internode reflect its specific degree of incongruence, and the TC and TCA values describe the global degree of incongruence between trees in the set. All four measures are implemented and freely available in version 8.0.0 and subsequent versions of the widely used program RAxML.

A bijection between phylogenetic trees and plane oriented recursive trees

OpenAIRE

Prodinger, Helmut

2017-01-01

Phylogenetic trees are binary nonplanar trees with labelled leaves, and plane oriented recursive trees are planar trees with an increasing labelling. Both families are enumerated by double factorials. A bijection is constructed, using the respective representations a 2-partitions and trapezoidal words.

Effects of elevated CO2 leaf diet on gypsy moth (Lepidoptera: Lymantriidae) respiration rates

Science.gov (United States)

Anita R. Foss; William J. Mattson; Terry M. Trier

2013-01-01

Elevated levels of CO2 affect plant growth and leaf chemistry, which in turn can alter host plant suitability for insect herbivores. We examined the suitability of foliage from trees grown from seedlings since 1997 at Aspen FACE as diet for the gypsy moth (Lymantria dispar L.) Lepidoptera: Lymantriidae: paper birch (...

Rate of tree carbon accumulation increases continuously with tree size

Science.gov (United States)

Stephenson, N.L.; Das, A.J.; Condit, R.; Russo, S.E.; Baker, P.J.; Beckman, N.G.; Coomes, D.A.; Lines, E.R.; Morris, W.K.; Rüger, N.; Álvarez, E.; Blundo, C.; Bunyavejchewin, S.; Chuyong, G.; Davies, S.J.; Duque, Á.; Ewango, C.N.; Flores, O.; Franklin, J.F.; Grau, H.R.; Hao, Z.; Harmon, M.E.; Hubbell, S.P.; Kenfack, D.; Lin, Y.; Makana, J.-R.; Malizia, A.; Malizia, L.R.; Pabst, R.J.; Pongpattananurak, N.; Su, S.-H.; Sun, I-F.; Tan, S.; Thomas, D.; van Mantgem, P.J.; Wang, X.; Wiser, S.K.; Zavala, M.A.

2014-01-01

Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle—particularly net primary productivity and carbon storage - increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree’s total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to understand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

HERB RECOVERY IN DEGRADED CAATINGA SITES ENRICHED WITH NATIVE TREES

Directory of Open Access Journals (Sweden)

Juliana Matos Figueiredo

2017-01-01

Full Text Available Herb recovery was evaluated in degraded Caatinga sites protected from grazing and enriched with native trees, in Patos-PB state, Brazil . Treatments were randomized according to a block design with five treatments (no tree planting –T 0 – or tree planting of three tree species in pure –T 1 = Poincianella pyramidalis , T 2 = Mimosa tenuiflora and T 3 = Cnidoscolus quercifolius – or mixed balanced stands –T 4 and five replications of squared-144-m 2 plots with 36 seedlings developing in planting holes enriched with manure and chemical fertilizers, arranged in a 2 m x 2 m grid. Data were collected from September 2008 to October 2009. After this period, natural tree regeneration was still not observed, and tree canopy covered 15 to 49% of the soil and did not affect herb growth and species composition. Initial and final herb cover were 16% and 100%, respectively. The number of dicot herbs increased from five, mainly two Sida species, to 13 species, monocots were represented by one species only (Aristida sp ., and quantity of herb forage reached 3 ton/ha (2:1, dicot:monocot. Adjacent overgrazed plots kept the initial low level of herb cover and species composition. Animal deferment during one year allowed the increase in soil cover and plant diversity in degraded Caatinga sites into which planted tree seedlings established successfully. This management practice could be implemented to avoid further environmental degradation and recover degraded areas.

An object-oriented classification method of high resolution imagery based on improved AdaTree

International Nuclear Information System (INIS)

Xiaohe, Zhang; Liang, Zhai; Jixian, Zhang; Huiyong, Sang

2014-01-01

With the popularity of the application using high spatial resolution remote sensing image, more and more studies paid attention to object-oriented classification on image segmentation as well as automatic classification after image segmentation. This paper proposed a fast method of object-oriented automatic classification. First, edge-based or FNEA-based segmentation was used to identify image objects and the values of most suitable attributes of image objects for classification were calculated. Then a certain number of samples from the image objects were selected as training data for improved AdaTree algorithm to get classification rules. Finally, the image objects could be classified easily using these rules. In the AdaTree, we mainly modified the final hypothesis to get classification rules. In the experiment with WorldView2 image, the result of the method based on AdaTree showed obvious accuracy and efficient improvement compared with the method based on SVM with the kappa coefficient achieving 0.9242

IcyTree: rapid browser-based visualization for phylogenetic trees and networks.

Science.gov (United States)

Vaughan, Timothy G

2017-08-01

IcyTree is an easy-to-use application which can be used to visualize a wide variety of phylogenetic trees and networks. While numerous phylogenetic tree viewers exist already, IcyTree distinguishes itself by being a purely online tool, having a responsive user interface, supporting phylogenetic networks (ancestral recombination graphs in particular), and efficiently drawing trees that include information such as ancestral locations or trait values. IcyTree also provides intuitive panning and zooming utilities that make exploring large phylogenetic trees of many thousands of taxa feasible. IcyTree is a web application and can be accessed directly at http://tgvaughan.github.com/icytree . Currently supported web browsers include Mozilla Firefox and Google Chrome. IcyTree is written entirely in client-side JavaScript (no plugin required) and, once loaded, does not require network access to run. IcyTree is free software, and the source code is made available at http://github.com/tgvaughan/icytree under version 3 of the GNU General Public License. tgvaughan@gmail.com. © The Author(s) 2017. Published by Oxford University Press.

TreeScaper: Visualizing and Extracting Phylogenetic Signal from Sets of Trees.

Science.gov (United States)

Huang, Wen; Zhou, Guifang; Marchand, Melissa; Ash, Jeremy R; Morris, David; Van Dooren, Paul; Brown, Jeremy M; Gallivan, Kyle A; Wilgenbusch, Jim C

2016-12-01

Modern phylogenomic analyses often result in large collections of phylogenetic trees representing uncertainty in individual gene trees, variation across genes, or both. Extracting phylogenetic signal from these tree sets can be challenging, as they are difficult to visualize, explore, and quantify. To overcome some of these challenges, we have developed TreeScaper, an application for tree set visualization as well as the identification of distinct phylogenetic signals. GUI and command-line versions of TreeScaper and a manual with tutorials can be downloaded from https://github.com/whuang08/TreeScaper/releases TreeScaper is distributed under the GNU General Public License. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Selection the Optimum Suppliers Compound Using a Mixed Model of MADM and Fault Tree Analysis

Directory of Open Access Journals (Sweden)

Meysam Azimian

2017-03-01

Full Text Available In this paper, an integrated approach of MADM and fault tree analysis (FTA is provided for determining the most reliable combination of suppliers for a strategic product in IUT University. At first, risks of suppliers is estimated by defining the indices for evaluating them, determining their relative status indices and using satisfying and SAW methods. Then, intrinsic risks of utilized equipments in the products are qualified and the final integrated risk for equipments is determined. Finally, through all the different scenarios, the best composition of equipment suppliers is selected by defining the palpable top events and fault tree analysis. The contribution of this paper is about proposing an integrated method of MADM and FTA to determine the most reliable suppliers in order to minimize the final risk of providing a product.

Flowering Trees

Indian Academy of Sciences (India)

IAS Admin

Flowering Trees. Ailanthus excelsa Roxb. (INDIAN TREE OF. HEAVEN) of Simaroubaceae is a lofty tree with large pinnately compound alternate leaves, which are ... inflorescences, unisexual and greenish-yellow. Fruits are winged, wings many-nerved. Wood is used in making match sticks. 1. Male flower; 2. Female flower.

Surface fluxes and water balance of spatially varying vegetation within a small mountainous headwater catchment

Directory of Open Access Journals (Sweden)

G. N. Flerchinger

2010-06-01

Full Text Available Precipitation variability and complex topography often create a mosaic of vegetation communities in mountainous headwater catchments, creating a challenge for measuring and interpreting energy and mass fluxes. Understanding the role of these communities in modulating energy, water and carbon fluxes is critical to quantifying the variability in energy, carbon, and water balances across landscapes. The focus of this paper was: (1 to demonstrate the utility of eddy covariance (EC systems in estimating the evapotranspiration component of the water balance of complex headwater mountain catchments; and (2 to compare and contrast the seasonal surface energy and carbon fluxes across a headwater catchment characterized by large variability in precipitation and vegetation cover. Eddy covariance systems were used to measure surface fluxes over sagebrush (Artemesia arbuscula and Artemesia tridentada vaseyana, aspen (Populus tremuloides and the understory of grasses and forbs beneath the aspen canopy. Peak leaf area index of the sagebrush, aspen, and aspen understory was 0.77, 1.35, and 1.20, respectively. The sagebrush and aspen canopies were subject to similar meteorological forces, while the understory of the aspen was sheltered from the wind. Missing periods of measured data were common and made it necessary to extrapolate measured fluxes to the missing periods using a combination of measured and simulated data. Estimated cumulative evapotranspiratation from the sagebrush, aspen trees, and aspen understory were 384 mm, 314 mm and 185 mm. A water balance of the catchment indicated that of the 699 mm of areal average precipitation, 421 mm was lost to evapotranspiration, and 254 mm of streamflow was measured from the catchment; water balance closure for the catchment was within 22 mm. Fluxes of latent heat and carbon for all sites were minimal through the winter. Growing season fluxes of latent heat and carbon were consistently higher

Elevated CO2 response of photosynthesis depends on ozone concentration in aspen

International Nuclear Information System (INIS)

Noormets, Asko; Kull, Olevi; Sober, Anu; Kubiske, Mark E.; Karnosky, David F.

2010-01-01

The effect of elevated CO 2 and O 3 on apparent quantum yield (φ), maximum photosynthesis (P max ), carboxylation efficiency (V cmax ) and electron transport capacity (J max ) at different canopy locations was studied in two aspen (Populus tremuloides) clones of contrasting O 3 tolerance. Local light climate at every leaf was characterized as fraction of above-canopy photosynthetic photon flux density (%PPFD). Elevated CO 2 alone did not affect φ or P max , and increased J max in the O 3 -sensitive, but not in the O 3 -tolerant clone. Elevated O 3 decreased leaf chlorophyll content and all photosynthetic parameters, particularly in the lower canopy, and the negative impact of O 3 increased through time. Significant interaction effect, whereby the negative impact of elevated O 3 was exaggerated by elevated CO 2 was seen in Chl, N and J max , and occurred in both O 3 -tolerant and O 3 -sensitive clones. The clonal differences in the level of CO 2 x O 3 interaction suggest a relationship between photosynthetic acclimation and background O 3 concentration. - Photosynthetic acclimation to elevated CO 2 depends on the background oxidant levels.

Recovery of crown mass for energy with whole-tree skidding methods; Puupolttoaineen tuottaminen kokopuujuontomenetelmillae

Energy Technology Data Exchange (ETDEWEB)

Nousiainen, I [Finntech Ltd Oy, Jyvaeskylae (Finland); Vesisenaho, T [VTT Energy, Jyvaeskylae (Finland)

1997-12-31

The main aim of the project `Recovery of crown mass for energy with whole-tree skidding methods` was to develop the integrated harvesting method of wood raw material and wood fuel based on whole-tree skidding. The developed method gives also the possibility to deliver to sawmills raw material in the form of log section. In the harvesting chain under development whole-trees are felled and bunched with a normal one-grip harvester. The whole-trees are skidded to the roadside by a forwarder equipped with a clam bunk. At the roadside the trees are delimbed and cut with the one-grip harvester used for felling and bunching. According to the results of the field tests the harvesting costs of logging residues are in certain final cutting conditions even under 10 FIM/m{sup 3}, when the average stem size is over 0,500 m{sup 3}. In the developed method felling and bunching of whole trees with the one-grip harvester and skidding of whole-trees with the clam skidder succeeded well. The problems of the method concentrate on delimbing and bucking of whole-trees in landing site

Recovery of crown mass for energy with whole-tree skidding methods; Puupolttoaineen tuottaminen kokopuujuontomenetelmillae

Energy Technology Data Exchange (ETDEWEB)

Nousiainen, I. [Finntech Ltd Oy, Jyvaeskylae (Finland); Vesisenaho, T. [VTT Energy, Jyvaeskylae (Finland)

1996-12-31

The main aim of the project `Recovery of crown mass for energy with whole-tree skidding methods` was to develop the integrated harvesting method of wood raw material and wood fuel based on whole-tree skidding. The developed method gives also the possibility to deliver to sawmills raw material in the form of log section. In the harvesting chain under development whole-trees are felled and bunched with a normal one-grip harvester. The whole-trees are skidded to the roadside by a forwarder equipped with a clam bunk. At the roadside the trees are delimbed and cut with the one-grip harvester used for felling and bunching. According to the results of the field tests the harvesting costs of logging residues are in certain final cutting conditions even under 10 FIM/m{sup 3}, when the average stem size is over 0,500 m{sup 3}. In the developed method felling and bunching of whole trees with the one-grip harvester and skidding of whole-trees with the clam skidder succeeded well. The problems of the method concentrate on delimbing and bucking of whole-trees in landing site

Monitoring the Soil Water Availability of Young Urban Trees in Hamburg, Germany

Science.gov (United States)

Titel, Selina; Gröngröft, Alexander; Eschenbach, Annette

2017-04-01

In large cities numerous trees have to be planted each year to replace died off or cut down trees or for greening of constructed roads and newly built quarters. The typical age of planted trees is between five and fifteen years. Often the planting takes place in special planting pits to stimulate the tree growth under the restricted urban conditions. Consequently, trees are surrounded by different soil substrates: the soil from the nursery in the root ball, the special planting pit substrate and the surrounding urban soil which is often anthropogenic influenced. Being relocated in the city, trees have to cope with the warmer urban climate, the soil sealing and compaction and the low water storage capacity of the substrate. All factors together increase the probability of dry phases for roadside trees. The aim of this study is to monitor the soil water availability at sites of planted roadside trees during the first years after planting. Therefore, a measuring design was developed, which works automatically and takes the complex below ground structure of the soil into account. This approach consists of 13 soil water tension sensors inside and outside of each planting pit up to one meter depth connected to a data logger. The monitoring devices will finally be installed at 20 roadside trees (amongst others Quercus cerris, Quercus robur, Acer platanoides 'Fairview') in Hamburg, Germany, to identify phases of drought stress. The young trees were mainly planted in spring 2016. Data of the first year of measurements show, that the water tension varied between the different soil substrates and the depth. In the first year of tree growth in the city, soil in the tree root ball became significantly drier than the surrounding soil material. In late summer 2016 the water tension in the topsoil had the potential to cause drought stress below some trees.

Tree detection in urban regions from aerial imagery and DSM based on local maxima points

Science.gov (United States)

Korkmaz, Özgür; Yardımcı ćetin, Yasemin; Yilmaz, Erdal

2017-05-01

In this study, we propose an automatic approach for tree detection and classification in registered 3-band aerial images and associated digital surface models (DSM). The tree detection results can be used in 3D city modelling and urban planning. This problem is magnified when trees are in close proximity to each other or other objects such as rooftops in the scenes. This study presents a method for locating individual trees and estimation of crown size based on local maxima from DSM accompanied by color and texture information. For this purpose, segment level classifier trained for 10 classes and classification results are improved by analyzing the class probabilities of neighbour segments. Later, the tree classes under a certain height were eliminated using the Digital Terrain Model (DTM). For the tree classes, local maxima points are obtained and the tree radius estimate is made from the vertical and horizontal height profiles passing through these points. The final tree list containing the centers and radius of the trees is obtained by selecting from the list of tree candidates according to the overlapping and selection parameters. Although the limited number of train sets are used in this study, tree classification and localization results are competitive.

Growth-climate relationships across topographic gradients in the northern Great Lakes

Science.gov (United States)

Dymond, S.F.; D'Amato, A.W.; Kolka, R.K.; Bolstad, P.V.; Sebestyen, S.D.; Bradford, John B.

2016-01-01

Climatic conditions exert important control over the growth, productivity, and distribution of forests, and characterizing these relationships is essential for understanding how forest ecosystems will respond to climate change. We used dendrochronological methods to develop climate–growth relationships for two dominant species, Populus tremuloides (quaking aspen) and Pinus resinosa (red pine), in the upper Great Lakes region to understand how climate and water availability influence annual forest productivity. Trees were sampled along a topographic gradient at the Marcell Experimental Forest (Minnesota, USA) to assess growth response to variations in temperature and different water availability metrics (precipitation, potential evapotranspiration (PET), cumulative moisture index (CMI), and soil water storage). Climatic variables were able to explain 33–58% of the variation in annual growth (as measured by ring-width increment) for quaking aspen and 37–74% of the variation for red pine. Climate–growth relationships were influenced by topography for quaking aspen but not for red pine. Annual ring growth for quaking aspen decreased with June CMI on ridges, decreased with temperature in the November prior to the growing season on sideslopes, and decreased with June PET on toeslopes. Red pine growth increased with increasing July PET across all topographic positions. These results indicate the sensitivity of both quaking aspen and red pine to local climate and show several vulnerabilities of these species to shifts in water supply and temperature because of climate change.

Flowering Trees

Indian Academy of Sciences (India)

Flowering Trees. Gyrocarpus americanus Jacq. (Helicopter Tree) of Hernandiaceae is a moderate size deciduous tree that grows to about 12 m in height with a smooth, shining, greenish-white bark. The leaves are ovate, rarely irregularly ... flowers which are unpleasant smelling. Fruit is a woody nut with two long thin wings.

Photosynthesis and carbon isotope discrimination in boreal forest ecosystems: A comparison of functional characteristics in plants from three mature forest types

Science.gov (United States)

Flanagan, Lawrence B.; Brooks, J. Renee; Ehleringer, James R.

1997-12-01

In this paper we compare measurements of photosynthesis and carbon isotope discrimination characteristics among plants from three mature boreal forest types (Black spruce, Jack pine, and aspen) in order to help explain variation in ecosystem-level gas exchange processes. Measurements were made at the southern study area (SSA) and northern study area (NSA) of the boreal forest in central Canada as part of the Boreal Ecosystem-Atmosphere Study (BOREAS). In both the NSA and the SSA there were significant differences in photosynthesis among the major tree species, with aspen having the highest CO2 assimilation rates and spruce the lowest. Within a species, photosynthetic rates in the SSA were approximately twice those measured in the NSA, and this was correlated with similar variations in stomatal conductance. Calculations of the ratio of leaf intercellular to ambient CO2 concentration (ci/ca) from leaf carbon isotope discrimination (Δ) values indicated a relatively low degree of stomatal limitation of photosynthesis, despite the low absolute values of stomatal conductance in these boreal tree species. Within each ecosystem, leaf Δ values were strongly correlated with life-form groups (trees, shrubs, forbs, and mosses), and these differences are maintained between years. Although we observed significant variation in the 13C content of tree rings at the old Jack pine site in the NSA during the past decade (indicating interannual variation in the degree of stomatal limitation), changes in summer precipitation and temperature accounted for only 44% of the isotopic variance. We scaled leaf-level processes to the ecosystem level through analyses of well-mixed canopy air. On average, all three forest types had similar ecosystem-level Δ values (average value ± standard deviation, 19.1‰±0.5‰), calculated from measurements of change in the concentration and carbon isotope ratio of atmospheric CO2 during a diurnal cycle within a forest canopy. However, there were

Cache-Oblivious Search Trees via Binary Trees of Small Height

DEFF Research Database (Denmark)

Brodal, G.S.; Fagerberg, R.; Jacob, R.

2002-01-01

We propose a version of cache oblivious search trees which is simpler than the previous proposal of Bender, Demaine and Farach-Colton and has the same complexity bounds. In particular, our data structure avoids the use of weight balanced B-trees, and can be implemented as just a single array......, and range queries in worst case O(logB n + k/B) memory transfers, where k is the size of the output.The basic idea of our data structure is to maintain a dynamic binary tree of height log n+O(1) using existing methods, embed this tree in a static binary tree, which in turn is embedded in an array in a cache...... oblivious fashion, using the van Emde Boas layout of Prokop.We also investigate the practicality of cache obliviousness in the area of search trees, by providing an empirical comparison of different methods for laying out a search tree in memory....

Review of the severe accident risk reduction program (SARRP) containment event trees

International Nuclear Information System (INIS)

1986-05-01

A part of the Severe Accident Risk Reduction Program, researchers at Sandia National Laboratories have constructed a group of containment event trees to be used in the analysis of key accident sequences for light water reactors (LWR) during postulated severe accidents. The ultimate goal of the program is to provide to the NRC staff a current assessment of the risk from severe reactor accidents for a group of five light water reactors. This review specifically focuses on the development and construction of the containment event trees and the results for containment failure probability, modes and timing. The report first gives the background on the program, the review criteria, and a summary of the observations, findings and recommendations. secondly, the individual reviews of each committee member on the event trees is presented. Finally, a review is provided on the computer model used to construct and evaluate the event trees

Flowering Trees

Indian Academy of Sciences (India)

Flowering Trees. Boswellia serrata Roxb. ex Colebr. (Indian Frankincense tree) of Burseraceae is a large-sized deciduous tree that is native to India. Bark is thin, greenish-ash-coloured that exfoliates into smooth papery flakes. Stem exudes pinkish resin ... Fruit is a three-valved capsule. A green gum-resin exudes from the ...

Automatic fault tree generation in the EPR PSA project

International Nuclear Information System (INIS)

Villatte, N; Nonclercq, P.; Taupy, S.

2012-01-01

Tools (KB3 and Atelier EPS) have been developed at EDF to assist the analysts in building fault trees for PSA (Probabilistic Safety Assessment) and importing them into RiskSpectrum (RiskSpectrum is a Swedish code used at EDF for PSA). System modelling is performed using KB3 software with a knowledge base describing generic classes of components with their behaviour and failure modes. Using these classes of components, the analyst can describe (using a graphical system editor): a simplified system diagram from the mechanical system drawings and functional descriptions, the missions of the studied system (in a form of high level fault trees) and its different configurations for the missions. He can also add specific knowledge about the system. Then, the analyst chooses missions and configurations to specify and launch fault trees generations. From the system description, KB3 produces by backward-chaining on rules, detailed system fault trees. These fault trees are finally imported into RiskSpectrum (they are converted by Atelier EPS into a format readable by RiskSpectrum). KB3 and Atelier EPS have been used to create the majority of the fault trees for the EDF EPR Probabilistic Safety Analysis conducted from November 2009 to March 2010. 25 systems were modelled, and 127 fault trees were automatically generated in a rather short time by different analysts with the help of these tools. A feedback shows a lot of advantages to use KB3 and Atelier EPS: homogeneity and consistency between the different generated fault trees, traceability of modelling, control of modelling and last but not least: the automation of detailed fault tree creation relieves the human analyst of this tedious task so that he can focus his attention on more important tasks: modelling the failure of a function. This industrial application has also helped us gather an interesting feedback from the analysts that should help us improve the handling of the tools. We propose in this paper indeed some

Systolic trees and systolic language recognition by tree automata

Energy Technology Data Exchange (ETDEWEB)

Steinby, M

1983-01-01

K. Culik II, J. Gruska, A. Salomaa and D. Wood have studied the language recognition capabilities of certain types of systolically operating networks of processors (see research reports Cs-81-32, Cs-81-36 and Cs-82-01, Univ. of Waterloo, Ontario, Canada). In this paper, their model for systolic VLSI trees is formalised in terms of standard tree automaton theory, and the way in which some known facts about recognisable forests and tree transductions can be applied in VLSI tree theory is demonstrated. 13 references.

DupTree: a program for large-scale phylogenetic analyses using gene tree parsimony.

Science.gov (United States)

Wehe, André; Bansal, Mukul S; Burleigh, J Gordon; Eulenstein, Oliver

2008-07-01

DupTree is a new software program for inferring rooted species trees from collections of gene trees using the gene tree parsimony approach. The program implements a novel algorithm that significantly improves upon the run time of standard search heuristics for gene tree parsimony, and enables the first truly genome-scale phylogenetic analyses. In addition, DupTree allows users to examine alternate rootings and to weight the reconciliation costs for gene trees. DupTree is an open source project written in C++. DupTree for Mac OS X, Windows, and Linux along with a sample dataset and an on-line manual are available at http://genome.cs.iastate.edu/CBL/DupTree

Rare itemsets mining algorithm based on RP-Tree and spark framework

Science.gov (United States)

Liu, Sainan; Pan, Haoan

2018-05-01

For the issues of the rare itemsets mining in big data, this paper proposed a rare itemsets mining algorithm based on RP-Tree and Spark framework. Firstly, it arranged the data vertically according to the transaction identifier, in order to solve the defects of scan the entire data set, the vertical datasets are divided into frequent vertical datasets and rare vertical datasets. Then, it adopted the RP-Tree algorithm to construct the frequent pattern tree that contains rare items and generate rare 1-itemsets. After that, it calculated the support of the itemsets by scanning the two vertical data sets, finally, it used the iterative process to generate rare itemsets. The experimental show that the algorithm can effectively excavate rare itemsets and have great superiority in execution time.

Mapping Urban Tree Canopy Cover Using Fused Airborne LIDAR and Satellite Imagery Data

Science.gov (United States)

Parmehr, Ebadat G.; Amati, Marco; Fraser, Clive S.

2016-06-01

Urban green spaces, particularly urban trees, play a key role in enhancing the liveability of cities. The availability of accurate and up-to-date maps of tree canopy cover is important for sustainable development of urban green spaces. LiDAR point clouds are widely used for the mapping of buildings and trees, and several LiDAR point cloud classification techniques have been proposed for automatic mapping. However, the effectiveness of point cloud classification techniques for automated tree extraction from LiDAR data can be impacted to the point of failure by the complexity of tree canopy shapes in urban areas. Multispectral imagery, which provides complementary information to LiDAR data, can improve point cloud classification quality. This paper proposes a reliable method for the extraction of tree canopy cover from fused LiDAR point cloud and multispectral satellite imagery data. The proposed method initially associates each LiDAR point with spectral information from the co-registered satellite imagery data. It calculates the normalised difference vegetation index (NDVI) value for each LiDAR point and corrects tree points which have been misclassified as buildings. Then, region growing of tree points, taking the NDVI value into account, is applied. Finally, the LiDAR points classified as tree points are utilised to generate a canopy cover map. The performance of the proposed tree canopy cover mapping method is experimentally evaluated on a data set of airborne LiDAR and WorldView 2 imagery covering a suburb in Melbourne, Australia.

Tree-rings and climate: Implications for Great Basin paleoenvironmental studies

International Nuclear Information System (INIS)

Graybill, D.A.; Rose, M.R.; Nials, F.L.

1994-01-01

The Quaternary Sciences Center of the Desert Research Institute is currently conducting a multi-phased study of floral, faunal, and geomorphic response to long- and short-term climate change and extremes in assessing Yucca Mountain's suitability as a high-level nuclear waste repository. Preliminary results of these studies indicate synchronous responses in late Holocene tree-ring, palynology and geomorphic records. A tree-ring chronology for paleoclimatic reconstruction is developed by collection of multiple cores from 20-60 living trees and a similar number of dead trees in a climate-sensitive location. Samples are cross-dated and every growth layer in each specimen is measured to the nearest .001 mm. The measured ring width series potentially contain a variety of climatic, biological, and anthropogenic signals. Each ring width series is subjected to a numerical standarization procedure that removes an age-related biological growth trend, reduces endogeneous and exogenous stand disturbance factors, and maximizes any climatic signal that is present. Each of these empirically defined components can be graphically portrayed and subjected to further analyses. The geophysical signal analysis techniques involved in the standarized protocol are well-documented and established. The final result is a tree-ring chronology that represents regional paleoclimatic variability over the time represented by the sample population

Flowering Trees

Indian Academy of Sciences (India)

More Details Fulltext PDF. Volume 8 Issue 8 August 2003 pp 112-112 Flowering Trees. Zizyphus jujuba Lam. of Rhamnaceae · More Details Fulltext PDF. Volume 8 Issue 9 September 2003 pp 97-97 Flowering Trees. Moringa oleifera · More Details Fulltext PDF. Volume 8 Issue 10 October 2003 pp 100-100 Flowering Trees.

Barrier to gene flow between two ecologically divergent Populus species, P. alba (white poplar) and P. tremula (European aspen): the role of ecology and life history in gene introgression.

Science.gov (United States)

Lexer, C; Fay, M F; Joseph, J A; Nica, M-S; Heinze, B

2005-04-01

The renewed interest in the use of hybrid zones for studying speciation calls for the identification and study of hybrid zones across a wide range of organisms, especially in long-lived taxa for which it is often difficult to generate interpopulation variation through controlled crosses. Here, we report on the extent and direction of introgression between two members of the "model tree" genus Populus: Populus alba (white poplar) and Populus tremula (European aspen), across a large zone of sympatry located in the Danube valley. We genotyped 93 hybrid morphotypes and samples from four parental reference populations from within and outside the zone of sympatry for a genome-wide set of 20 nuclear microsatellites and eight plastid DNA restriction site polymorphisms. Our results indicate that introgression occurs preferentially from P. tremula to P. alba via P. tremula pollen. This unidirectional pattern is facilitated by high levels of pollen vs. seed dispersal in P. tremula (pollen/seed flow = 23.9) and by great ecological opportunity in the lowland floodplain forest in proximity to P. alba seed parents, which maintains gene flow in the direction of P. alba despite smaller effective population sizes (N(e)) in this species (P. alba N(e)c. 500-550; P. tremula N(e)c. 550-700). Our results indicate that hybrid zones will be valuable tools for studying the genetic architecture of the barrier to gene flow between these two ecologically divergent Populus species.

Embedding complete ternary tree in hypercubes using AVL trees

NARCIS (Netherlands)

S.A. Choudum; I. Raman (Indhumathi)

2008-01-01

htmlabstractA complete ternary tree is a tree in which every non-leaf vertex has exactly three children. We prove that a complete ternary tree of height h, TTh, is embeddable in a hypercube of dimension . This result coincides with the result of [2]. However, in this paper, the embedding utilizes

Ghost-tree: creating hybrid-gene phylogenetic trees for diversity analyses.

Science.gov (United States)

Fouquier, Jennifer; Rideout, Jai Ram; Bolyen, Evan; Chase, John; Shiffer, Arron; McDonald, Daniel; Knight, Rob; Caporaso, J Gregory; Kelley, Scott T

2016-02-24

Fungi play critical roles in many ecosystems, cause serious diseases in plants and animals, and pose significant threats to human health and structural integrity problems in built environments. While most fungal diversity remains unknown, the development of PCR primers for the internal transcribed spacer (ITS) combined with next-generation sequencing has substantially improved our ability to profile fungal microbial diversity. Although the high sequence variability in the ITS region facilitates more accurate species identification, it also makes multiple sequence alignment and phylogenetic analysis unreliable across evolutionarily distant fungi because the sequences are hard to align accurately. To address this issue, we created ghost-tree, a bioinformatics tool that integrates sequence data from two genetic markers into a single phylogenetic tree that can be used for diversity analyses. Our approach starts with a "foundation" phylogeny based on one genetic marker whose sequences can be aligned across organisms spanning divergent taxonomic groups (e.g., fungal families). Then, "extension" phylogenies are built for more closely related organisms (e.g., fungal species or strains) using a second more rapidly evolving genetic marker. These smaller phylogenies are then grafted onto the foundation tree by mapping taxonomic names such that each corresponding foundation-tree tip would branch into its new "extension tree" child. We applied ghost-tree to graft fungal extension phylogenies derived from ITS sequences onto a foundation phylogeny derived from fungal 18S sequences. Our analysis of simulated and real fungal ITS data sets found that phylogenetic distances between fungal communities computed using ghost-tree phylogenies explained significantly more variance than non-phylogenetic distances. The phylogenetic metrics also improved our ability to distinguish small differences (effect sizes) between microbial communities, though results were similar to non

An upper bound on the number of independent sets in a tree

DEFF Research Database (Denmark)

Pedersen, Anders Sune

2007-01-01

The main result of this paper is an upper bound on the number of independent sets in a tree in terms of the order and diameter of the tree. This new upper bound is a refinement of the bound given by Prodinger and Tichy [ Fibonacci Q., 20 (1982), no. 1, 16-21]. Finally, we give a sufficient...... condition for the new upper bound to be better thatn the upper bound given by Brigham, Chandrasekharan and Dutton [ Fibonacci Q., 31 (1993), no. 2, 98-104]....

An upper bound on the number of independent sets in a tree

DEFF Research Database (Denmark)

Vestergaard, Preben Dahl; Pedersen, Anders Sune

The main result of this paper is an upper bound on the number of independent sets in a tree in terms of the order and diameter of the tree. This new upper bound is a refinement of the bound given by Prodinger and Tichy [Fibonacci Q., 20 (1982), no. 1, 16-21]. Finally, we give a sufficient condition...... for the new upper bound to be better than the upper bound given by Brigham, Chandrasekharan and Dutton [Fibonacci Q., 31 (1993), no. 2, 98-104]....

Trees are good, but…

Science.gov (United States)

E.G. McPherson; F. Ferrini

2010-01-01

We know that “trees are good,” and most people believe this to be true. But if this is so, why are so many trees neglected, and so many tree wells empty? An individual’s attitude toward trees may result from their firsthand encounters with specific trees. Understanding how attitudes about trees are shaped, particularly aversion to trees, is critical to the business of...

Multiple-purpose trees for pastoral farming in New Zealand: with emphasis on tree legumes. [Lucerne Tree: Medick Tree

Energy Technology Data Exchange (ETDEWEB)

Davies, D J.G.; Macfarlane, R P

1979-01-01

The potential for soil conservation and agroforestry of several native and exotic legumes is discussed. Flowering period, chemical composition of leaves/pods, hardiness to frost and drought, timber value, forage potential for livestock and bees, ornamental value and other products are tabulated with information on up to 38 species. Two low-growing species that have proved useful for slope stabilization as well as forage are tree lucerne (Cytisus palmensis) and tree medick (Medicago arborea), the latter being shrubby and more suitable for cold districts. Gleditsia triacanthos is recommended as a shade and fodder tree for farm pasture.

Development and Validation of Spatially Explicit Habitat Models for Cavity-nesting Birds in Fishlake National Forest, Utah

Science.gov (United States)

Randall A., Jr. Schultz; Thomas C., Jr. Edwards; Gretchen G. Moisen; Tracey S. Frescino

2005-01-01

The ability of USDA Forest Service Forest Inventory and Analysis (FIA) generated spatial products to increase the predictive accuracy of spatially explicit, macroscale habitat models was examined for nest-site selection by cavity-nesting birds in Fishlake National Forest, Utah. One FIA-derived variable (percent basal area of aspen trees) was significant in the habitat...

Shedding light on tree growth : ring analysis of juvenile tropical trees

NARCIS (Netherlands)

Soliz Gamboa, C.C.

2010-01-01

In the understory of tropical forests light is believed to be the main limiting growth factor for the newly established trees. Trees growing in shade of the understory may experience periods of slow radial growth. It is expected that gaps created by tree or branch fall will provoke tree growth

Inferring species trees from incongruent multi-copy gene trees using the Robinson-Foulds distance

Science.gov (United States)

2013-01-01

Background Constructing species trees from multi-copy gene trees remains a challenging problem in phylogenetics. One difficulty is that the underlying genes can be incongruent due to evolutionary processes such as gene duplication and loss, deep coalescence, or lateral gene transfer. Gene tree estimation errors may further exacerbate the difficulties of species tree estimation. Results We present a new approach for inferring species trees from incongruent multi-copy gene trees that is based on a generalization of the Robinson-Foulds (RF) distance measure to multi-labeled trees (mul-trees). We prove that it is NP-hard to compute the RF distance between two mul-trees; however, it is easy to calculate this distance between a mul-tree and a singly-labeled species tree. Motivated by this, we formulate the RF problem for mul-trees (MulRF) as follows: Given a collection of multi-copy gene trees, find a singly-labeled species tree that minimizes the total RF distance from the input mul-trees. We develop and implement a fast SPR-based heuristic algorithm for the NP-hard MulRF problem. We compare the performance of the MulRF method (available at http://genome.cs.iastate.edu/CBL/MulRF/) with several gene tree parsimony approaches using gene tree simulations that incorporate gene tree error, gene duplications and losses, and/or lateral transfer. The MulRF method produces more accurate species trees than gene tree parsimony approaches. We also demonstrate that the MulRF method infers in minutes a credible plant species tree from a collection of nearly 2,000 gene trees. Conclusions Our new phylogenetic inference method, based on a generalized RF distance, makes it possible to quickly estimate species trees from large genomic data sets. Since the MulRF method, unlike gene tree parsimony, is based on a generic tree distance measure, it is appealing for analyses of genomic data sets, in which many processes such as deep coalescence, recombination, gene duplication and losses as

A time-dependent event tree technique for modelling recovery operations

International Nuclear Information System (INIS)

Kohut, P.; Fitzpatrick, R.

1991-01-01

The development of a simplified time dependent event tree methodology is presented. The technique is especially applicable to describe recovery operations in nuclear reactor accident scenarios initiated by support system failures. The event tree logic is constructed using time dependent top events combined with a damage function that contains information about the final state time behavior of the reactor core. Both the failure and the success states may be utilized for the analysis. The method is illustrated by modeling the loss of service water function with special emphasis on the RCP [reactor coolant pump] seal LOCA [loss of coolant accident] scenario. 5 refs., 2 figs., 2 tabs

Microcomputer applications of, and modifications to, the modular fault trees

International Nuclear Information System (INIS)

Zimmerman, T.L.; Graves, N.L.; Payne, A.C. Jr.; Whitehead, D.W.

1994-10-01

The LaSalle Probabilistic Risk Assessment was the first major application of the modular logic fault trees after the IREP program. In the process of performing the analysis, many errors were discovered in the fault tree modules that led to difficulties in combining the modules to form the final system fault trees. These errors are corrected in the revised modules listed in this report. In addition, the application of the modules in terms of editing them and forming them into the system fault trees was inefficient. Originally, the editing had to be done line by line and no error checking was performed by the computer. This led to many typos and other logic errors in the construction of the modular fault tree files. Two programs were written to help alleviate this problem: (1) MODEDIT - This program allows an operator to retrieve a file for editing, edit the file for the plant specific application, perform some general error checking while the file is being modified, and store the file for later use, and (2) INDEX - This program checks that the modules that are supposed to form one fault tree all link up appropriately before the files are,loaded onto the mainframe computer. Lastly, the modules were not designed for relay type logic common in BWR designs but for solid state type logic. Some additional modules were defined for modeling relay logic, and an explanation and example of their use are included in this report

Trees

Science.gov (United States)

Al-Khaja, Nawal

2007-01-01

This is a thematic lesson plan for young learners about palm trees and the importance of taking care of them. The two part lesson teaches listening, reading and speaking skills. The lesson includes parts of a tree; the modal auxiliary, can; dialogues and a role play activity.

An object-based approach for tree species extraction from digital orthophoto maps

Science.gov (United States)

Jamil, Akhtar; Bayram, Bulent

2018-05-01

Tree segmentation is an active and ongoing research area in the field of photogrammetry and remote sensing. It is more challenging due to both intra-class and inter-class similarities among various tree species. In this study, we exploited various statistical features for extraction of hazelnut trees from 1 : 5000 scaled digital orthophoto maps. Initially, the non-vegetation areas were eliminated using traditional normalized difference vegetation index (NDVI) followed by application of mean shift segmentation for transforming the pixels into meaningful homogeneous objects. In order to eliminate false positives, morphological opening and closing was employed on candidate objects. A number of heuristics were also derived to eliminate unwanted effects such as shadow and bounding box aspect ratios, before passing them into the classification stage. Finally, a knowledge based decision tree was constructed to distinguish the hazelnut trees from rest of objects which include manmade objects and other type of vegetation. We evaluated the proposed methodology on 10 sample orthophoto maps obtained from Giresun province in Turkey. The manually digitized hazelnut tree boundaries were taken as reference data for accuracy assessment. Both manually digitized and segmented tree borders were converted into binary images and the differences were calculated. According to the obtained results, the proposed methodology obtained an overall accuracy of more than 85 % for all sample images.

Spectra of chemical trees

International Nuclear Information System (INIS)

Balasubramanian, K.

1982-01-01

A method is developed for obtaining the spectra of trees of NMR and chemical interests. The characteristic polynomials of branched trees can be obtained in terms of the characteristic polynomials of unbranched trees and branches by pruning the tree at the joints. The unbranched trees can also be broken down further until a tree containing just two vertices is obtained. The effectively reduces the order of the secular determinant of the tree used at the beginning to determinants of orders atmost equal to the number of vertices in the branch containing the largest number of vertices. An illustrative example of a NMR graph is given for which the 22 x 22 secular determinant is reduced to determinants of orders atmost 4 x 4 in just the second step of the algorithm. The tree pruning algorithm can be applied even to trees with no symmetry elements and such a factoring can be achieved. Methods developed here can be elegantly used to find if two trees are cospectral and to construct cospectral trees

Decision trees and decision committee applied to star/galaxy separation problem

Science.gov (United States)

Vasconcellos, Eduardo Charles

Vasconcellos et al [1] study the efficiency of 13 diferente decision tree algorithms applied to photometric data in the Sloan Digital Sky Digital Survey Data Release Seven (SDSS-DR7) to perform star/galaxy separation. Each algorithm is defined by a set fo parameters which, when varied, produce diferente final classifications trees. In that work we extensively explore the parameter space of each algorithm, using the set of 884,126 SDSS objects with spectroscopic data as the training set. We find that Functional Tree algorithm (FT) yields the best results by the mean completeness function (galaxy true positive rate) in two magnitude intervals:14=19 (82.1%). We compare FT classification to the SDSS parametric, 2DPHOT and Ball et al (2006) classifications. At the faintest magnitudes (r > 19), our classifier is the only one that maintains high completeness (>80%) while simultaneously achieving low contamination ( 2.5%). We also examine the SDSS parametric classifier (psfMag - modelMag) to see if the dividing line between stars and galaxies can be adjusted to improve the classifier. We find that currently stars in close pairs are often misclassified as galaxies, and suggest a new cut to improve the classifier. Finally, we apply our FT classifier to separate stars from galaxies in the full set of 69,545,326 SDSS photometric objects in the magnitude range 14 train six FT classifiers with random selected objects from the same 884,126 SDSS-DR7 objects with spectroscopic data that we use before. Both, the decision commitee and our previous single FT classifier will be applied to the new ojects from SDSS data releses eight, nine and ten. Finally we will compare peformances of both methods in this new data set. [1] Vasconcellos, E. C.; de Carvalho, R. R.; Gal, R. R.; LaBarbera, F. L.; Capelato, H. V.; Fraga Campos Velho, H.; Trevisan, M.; Ruiz, R. S. R.. Decision Tree Classifiers for Star/Galaxy Separation. The Astronomical Journal, Volume 141, Issue 6, 2011.

MeshTree: A Delay optimised Overlay Multicast Tree Building Protocol

OpenAIRE

Tan, Su-Wei; Waters, A. Gill; Crawford, John

2005-01-01

We study decentralised low delay degree-constrained overlay multicast tree construction for single source real-time applications. This optimisation problem is NP-hard even if computed centrally. We identify two problems in traditional distributed solutions, namely the greedy problem and delay-cost trade-off. By offering solutions to these problems, we propose a new self-organising distributed tree building protocol called MeshTree. The main idea is to embed the delivery tree in a degree-bound...

Minimum variance rooting of phylogenetic trees and implications for species tree reconstruction.

Science.gov (United States)

Mai, Uyen; Sayyari, Erfan; Mirarab, Siavash

2017-01-01

Phylogenetic trees inferred using commonly-used models of sequence evolution are unrooted, but the root position matters both for interpretation and downstream applications. This issue has been long recognized; however, whether the potential for discordance between the species tree and gene trees impacts methods of rooting a phylogenetic tree has not been extensively studied. In this paper, we introduce a new method of rooting a tree based on its branch length distribution; our method, which minimizes the variance of root to tip distances, is inspired by the traditional midpoint rerooting and is justified when deviations from the strict molecular clock are random. Like midpoint rerooting, the method can be implemented in a linear time algorithm. In extensive simulations that consider discordance between gene trees and the species tree, we show that the new method is more accurate than midpoint rerooting, but its relative accuracy compared to using outgroups to root gene trees depends on the size of the dataset and levels of deviations from the strict clock. We show high levels of error for all methods of rooting estimated gene trees due to factors that include effects of gene tree discordance, deviations from the clock, and gene tree estimation error. Our simulations, however, did not reveal significant differences between two equivalent methods for species tree estimation that use rooted and unrooted input, namely, STAR and NJst. Nevertheless, our results point to limitations of existing scalable rooting methods.

Decomposing the Site Frequency Spectrum: The Impact of Tree Topology on Neutrality Tests.

Science.gov (United States)

Ferretti, Luca; Ledda, Alice; Wiehe, Thomas; Achaz, Guillaume; Ramos-Onsins, Sebastian E

2017-09-01

We investigate the dependence of the site frequency spectrum on the topological structure of genealogical trees. We show that basic population genetic statistics, for instance, estimators of θ or neutrality tests such as Tajima's D , can be decomposed into components of waiting times between coalescent events and of tree topology. Our results clarify the relative impact of the two components on these statistics. We provide a rigorous interpretation of positive or negative values of an important class of neutrality tests in terms of the underlying tree shape. In particular, we show that values of Tajima's D and Fay and Wu's H depend in a direct way on a peculiar measure of tree balance, which is mostly determined by the root balance of the tree. We present a new test for selection in the same class as Fay and Wu's H and discuss its interpretation and power. Finally, we determine the trees corresponding to extreme expected values of these neutrality tests and present formulas for these extreme values as a function of sample size and number of segregating sites. Copyright © 2017 by the Genetics Society of America.

Final Report on Regulation of Guaiacyl and Syringyl Monolignol Biosynthesis

Energy Technology Data Exchange (ETDEWEB)

Vincent L. Chiang

2006-03-09

The focus of this research is to understand syringyl monolignol biosynthesis that leads to the formation of syringyl lignin, a type of lignin that can be easily removed during biomass conversion. We have achieved the three originally proposed goals for this project. (1) SAD and CAD genes (enzyme catalytic and kinetic properties) and their functional relevance to CAld5H/AldOMT pathway, (2) spatiotemporal expression patterns of Cald5H, AldOMT, SAD and CAD genes, and (3) functions of CAld5H, AldOMT, and SAD genes in vivo using transgenic aspen. Furthermore, we also found that microRNA might be involved in the upstream regulatory network of lignin biosynthesis and wood formation. The achievements are as below. (1) Based on biochemical and molecular studies, we discovered a novel syringyl-specific alcohol dehydrogenase (SAD) involved in monolignol biosynthesis in angiosperm trees. Through CAld5H/OMT/SAD mediation, syringyl monolignol biosynthesis branches out from guaiacyl pathway at coniferaldehyde; (2) The function of CAld5H gene in this syringyl monolignol biosynthesis pathway also was confirmed in vivo in transgenic Populus; (3) The proposed major monolignol biosynthesis pathways were further supported by the involving biochemical functions of CCR based on a detailed kinetic study; (4) Gene promoter activity analysis also supported the cell-type specific expression of SAD and CAD genes in xylem tissue, consistent with the cell-specific locations of SAD and CAD proteins and with the proposed pathways; (5) We have developed a novel small interfering RNA (siRNA)-mediated stable gene-silencing system in transgenic plants; (6) Using the siRNA and P. trichocarpa transformation/regeneration systems we are currently producing transgenic P. trichocarpa to investigate the interactive functions of CAD and SAD in regulating guaiacyl and syringyl lignin biosynthesis; (7) We have cloned for the first time from a tree species, P. trichocarpa, small regulatory RNAs termed micro

TreePlus: interactive exploration of networks with enhanced tree layouts.

Science.gov (United States)

Lee, Bongshin; Parr, Cynthia S; Plaisant, Catherine; Bederson, Benjamin B; Veksler, Vladislav D; Gray, Wayne D; Kotfila, Christopher

2006-01-01

Despite extensive research, it is still difficult to produce effective interactive layouts for large graphs. Dense layout and occlusion make food webs, ontologies, and social networks difficult to understand and interact with. We propose a new interactive Visual Analytics component called TreePlus that is based on a tree-style layout. TreePlus reveals the missing graph structure with visualization and interaction while maintaining good readability. To support exploration of the local structure of the graph and gathering of information from the extensive reading of labels, we use a guiding metaphor of "Plant a seed and watch it grow." It allows users to start with a node and expand the graph as needed, which complements the classic overview techniques that can be effective at (but often limited to) revealing clusters. We describe our design goals, describe the interface, and report on a controlled user study with 28 participants comparing TreePlus with a traditional graph interface for six tasks. In general, the advantage of TreePlus over the traditional interface increased as the density of the displayed data increased. Participants also reported higher levels of confidence in their answers with TreePlus and most of them preferred TreePlus.

Growth effects after whole-tree harvest in final cut of Scots pine and Norway spruce forest. Final report; Tillvaexteffekternas storlek och uthaallighet efter skogsbraensleuttag i slutavverkning av tall och gran. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

Valinger, E. [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden). Dept. of Silviculture

2001-12-01

A great concern in forestry today is whether whole-tree harvesting influence site productivity and whether it is consistent with the principle of sustainable use of forest resources. To evaluate this a randomised field experiment established 24 years ago in Scots pine (Pinus sylvestris L.) in Southern Sweden was used. The field experiment was established in fall 1975 as a naturally regenerated mixed forest with Scots pine and Norway spruce (Picea abies (L.) Karst.) with a growing stock of 305 m{sup 3}/ha was clear-cut near Kosta (56 deg 52' N, 15 deg 50' E, 240 m.a.s.l.). The site was a mesic dwarf-shrub type of medium fertility, with an average precipitation of 600 mm yr-1 and the soil was an orthic podzol. Treatments were conventional stem harvest (CH), whole-tree harvest (WTH), and branch and stem harvest (BSH). Scots pine seedlings of local provenance were planted in spring 1977 at the beginning of the second growing season following the harvest. The seedlings were planted in exposed mineral soil in manually scarified patches (40 x 40 cm) at 1.7 m spacing (144 seedlings per assessment plot, i.e. 3 600 seedlings/ha). Based on calliper data, the diameter for the mean basal area per tree (db) was calculated for each plot after 24 years using the formula: db = ({sigma} b{sup 3}/{sigma} b{sup 2}), where b is basal area at breast height for each tree. Three undamaged sample trees with a diameter equal or close to the diameter of the mean basal area per tree were selected on each plot giving 36 stems that were felled for destructive measurements in 2000. Total tree height ({+-} 0.01 m) was measured on every tree felled. Stem biomass was estimated by sampling of stem discs, 2 cm thick, at stump height (1 % of tree height), breast height (1.3 m), and at every meter along the bole. Crown biomass was estimated by sampling live and dead branches on the felled trees. From every whorl of branches one living branch was sampled and all branches were counted. Stem

Density, size and distribution of stomata in 35 rainforest trees species in Central Amazonia

OpenAIRE

Miguel Angelo Branco Camargo; Ricardo Antonio Marenco

2011-01-01

Stomata are turgor-operated valves that control water loss and CO2 uptake during photosynthesis, and thereby water relation and plant biomass accumulation is closely related to stomatal functioning. The aims of this work were to document how stomata are distributed on the leaf surface and to determine if there is any significant variation in stomatal characteristics among Amazonian tree species, and finally to study the relationship between stomatal density (S D) and tree height. Thirty five ...

Density, size and distribution of stomata in 35 rainforest tree species in Central Amazonia

OpenAIRE

Camargo, Miguel Angelo Branco; Marenco, Ricardo Antonio

2011-01-01

Stomata are turgor-operated valves that control water loss and CO2 uptake during photosynthesis, and thereby water relation and plant biomass accumulation is closely related to stomatal functioning. The aims of this work were to document how stomata are distributed on the leaf surface and to determine if there is any significant variation in stomatal characteristics among Amazonian tree species, and finally to study the relationship between stomatal density (S D) and tree height. Thirty five ...

Simple street tree sampling

Science.gov (United States)

David J. Nowak; Jeffrey T. Walton; James Baldwin; Jerry. Bond

2015-01-01

Information on street trees is critical for management of this important resource. Sampling of street tree populations provides an efficient means to obtain street tree population information. Long-term repeat measures of street tree samples supply additional information on street tree changes and can be used to report damages from catastrophic events. Analyses of...

TreeFam: a curated database of phylogenetic trees of animal gene families

DEFF Research Database (Denmark)

Li, Heng; Coghlan, Avril; Ruan, Jue

2006-01-01

TreeFam is a database of phylogenetic trees of gene families found in animals. It aims to develop a curated resource that presents the accurate evolutionary history of all animal gene families, as well as reliable ortholog and paralog assignments. Curated families are being added progressively......, based on seed alignments and trees in a similar fashion to Pfam. Release 1.1 of TreeFam contains curated trees for 690 families and automatically generated trees for another 11 646 families. These represent over 128 000 genes from nine fully sequenced animal genomes and over 45 000 other animal proteins...

Biodiversity promotes tree growth during succession in subtropical forest.

Directory of Open Access Journals (Sweden)

Martin Barrufol

Full Text Available Losses of plant species diversity can affect ecosystem functioning, with decreased primary productivity being the most frequently reported effect in experimental plant assemblages, including tree plantations. Less is known about the role of biodiversity in natural ecosystems, including forests, despite their importance for global biogeochemical cycling and climate. In general, experimental manipulations of tree diversity will take decades to yield final results. To date, biodiversity effects in natural forests therefore have only been reported from sample surveys or meta-analyses with plots not initially selected for diversity. We studied biomass and growth of subtropical forests stands in southeastern China. Taking advantage of variation in species recruitment during secondary succession, we adopted a comparative study design selecting forest plots to span a gradient in species richness. We repeatedly censored the stem diameter of two tree size cohorts, comprising 93 species belonging to 57 genera and 33 families. Tree size and growth were analyzed in dependence of species richness, the functional diversity of growth-related traits, and phylogenetic diversity, using both general linear and structural equation modeling. Successional age covaried with diversity, but differently so in the two size cohorts. Plot-level stem basal area and growth were positively related with species richness, while growth was negatively related to successional age. The productivity increase in species-rich, functionally and phylogenetically diverse plots was driven by both larger mean sizes and larger numbers of trees. The biodiversity effects we report exceed those from experimental studies, sample surveys and meta-analyses, suggesting that subtropical tree diversity is an important driver of forest productivity and re-growth after disturbance that supports the provision of ecological services by these ecosystems.

Drought stress, growth and nonstructural carbohydrate dynamics of pine trees in a semi-arid forest.

Science.gov (United States)

Klein, Tamir; Hoch, Günter; Yakir, Dan; Körner, Christian

2014-09-01

In trees exposed to prolonged drought, both carbon uptake (C source) and growth (C sink) typically decrease. This correlation raises two important questions: (i) to what degree is tree growth limited by C availability; and (ii) is growth limited by concurrent C storage (e.g., as nonstructural carbohydrates, NSC)? To test the relationships between drought, growth and C reserves, we monitored the changes in NSC levels and constructed stem growth chronologies of mature Pinus halepensis Miller trees of three drought stress levels growing in Yatir forest, Israel, at the dry distribution limit of forests. Moderately stressed and stressed trees showed 34 and 14% of the stem growth, 71 and 31% of the sap flux density, and 79 and 66% of the final needle length of healthy trees in 2012. In spite of these large reductions in growth and sap flow, both starch and soluble sugar concentrations in the branches of these trees were similar in all trees throughout the dry season (2-4% dry mass). At the same time, the root starch concentrations of moderately stressed and stressed trees were 47 and 58% of those of healthy trees, but never drought there is more than one way for a tree to maintain a positive C balance. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Tree-space statistics and approximations for large-scale analysis of anatomical trees

DEFF Research Database (Denmark)

Feragen, Aasa; Owen, Megan; Petersen, Jens

2013-01-01

parametrize the relevant parts of tree-space well. Using the developed approximate statistics, we illustrate how the structure and geometry of airway trees vary across a population and show that airway trees with Chronic Obstructive Pulmonary Disease come from a different distribution in tree-space than...

Relating phylogenetic trees to transmission trees of infectious disease outbreaks.

Science.gov (United States)

Ypma, Rolf J F; van Ballegooijen, W Marijn; Wallinga, Jacco

2013-11-01

Transmission events are the fundamental building blocks of the dynamics of any infectious disease. Much about the epidemiology of a disease can be learned when these individual transmission events are known or can be estimated. Such estimations are difficult and generally feasible only when detailed epidemiological data are available. The genealogy estimated from genetic sequences of sampled pathogens is another rich source of information on transmission history. Optimal inference of transmission events calls for the combination of genetic data and epidemiological data into one joint analysis. A key difficulty is that the transmission tree, which describes the transmission events between infected hosts, differs from the phylogenetic tree, which describes the ancestral relationships between pathogens sampled from these hosts. The trees differ both in timing of the internal nodes and in topology. These differences become more pronounced when a higher fraction of infected hosts is sampled. We show how the phylogenetic tree of sampled pathogens is related to the transmission tree of an outbreak of an infectious disease, by the within-host dynamics of pathogens. We provide a statistical framework to infer key epidemiological and mutational parameters by simultaneously estimating the phylogenetic tree and the transmission tree. We test the approach using simulations and illustrate its use on an outbreak of foot-and-mouth disease. The approach unifies existing methods in the emerging field of phylodynamics with transmission tree reconstruction methods that are used in infectious disease epidemiology.

Decision-Tree Program

Science.gov (United States)

Buntine, Wray

1994-01-01

IND computer program introduces Bayesian and Markov/maximum-likelihood (MML) methods and more-sophisticated methods of searching in growing trees. Produces more-accurate class-probability estimates important in applications like diagnosis. Provides range of features and styles with convenience for casual user, fine-tuning for advanced user or for those interested in research. Consists of four basic kinds of routines: data-manipulation, tree-generation, tree-testing, and tree-display. Written in C language.

Tree-growth analyses to estimate tree species' drought tolerance.

Science.gov (United States)

Eilmann, Britta; Rigling, Andreas

2012-02-01

Climate change is challenging forestry management and practices. Among other things, tree species with the ability to cope with more extreme climate conditions have to be identified. However, while environmental factors may severely limit tree growth or even cause tree death, assessing a tree species' potential for surviving future aggravated environmental conditions is rather demanding. The aim of this study was to find a tree-ring-based method suitable for identifying very drought-tolerant species, particularly potential substitute species for Scots pine (Pinus sylvestris L.) in Valais. In this inner-Alpine valley, Scots pine used to be the dominating species for dry forests, but today it suffers from high drought-induced mortality. We investigate the growth response of two native tree species, Scots pine and European larch (Larix decidua Mill.), and two non-native species, black pine (Pinus nigra Arnold) and Douglas fir (Pseudotsuga menziesii Mirb. var. menziesii), to drought. This involved analysing how the radial increment of these species responded to increasing water shortage (abandonment of irrigation) and to increasingly frequent drought years. Black pine and Douglas fir are able to cope with drought better than Scots pine and larch, as they show relatively high radial growth even after irrigation has been stopped and a plastic growth response to drought years. European larch does not seem to be able to cope with these dry conditions as it lacks the ability to recover from drought years. The analysis of trees' short-term response to extreme climate events seems to be the most promising and suitable method for detecting how tolerant a tree species is towards drought. However, combining all the methods used in this study provides a complete picture of how water shortage could limit species.

Disentangling the Effects of Water Stress on Carbon Acquisition, Vegetative Growth, and Fruit Quality of Peach Trees by Means of the QualiTree Model

Directory of Open Access Journals (Sweden)

Mitra Rahmati

2018-01-01

Full Text Available Climate change projections predict warmer and drier conditions. In general, moderate to severe water stress reduce plant vegetative growth and leaf photosynthesis. However, vegetative and reproductive growths show different sensitivities to water deficit. In fruit trees, water restrictions may have serious implications not only on tree growth and yield, but also on fruit quality, which might be improved. Therefore, it is of paramount importance to understand the complex interrelations among the physiological processes involved in within-tree carbon acquisition and allocation, water uptake and transpiration, organ growth, and fruit composition when affected by water stress. This can be studied using process-based models of plant functioning, which allow assessing the sensitivity of various physiological processes to water deficit and their relative impact on vegetative growth and fruit quality. In the current study, an existing fruit-tree model (QualiTree was adapted for describing the water stress effects on peach (Prunus persica L. Batsch vegetative growth, fruit size and composition. First, an energy balance calculation at the fruit-bearing shoot level and a water transfer formalization within the plant were integrated into the model. Next, a reduction function of vegetative growth according to tree water status was added to QualiTree. Then, the model was parameterized and calibrated for a late-maturing peach cultivar (“Elberta” under semi-arid conditions, and for three different irrigation practices. Simulated vegetative and fruit growth variability over time was consistent with observed data. Sugar concentrations in fruit flesh were well simulated. Finally, QualiTree allowed for determining the relative importance of photosynthesis and vegetative growth reduction on carbon acquisition, plant growth and fruit quality under water constrains. According to simulations, water deficit impacted vegetative growth first through a direct effect on

Disentangling the Effects of Water Stress on Carbon Acquisition, Vegetative Growth, and Fruit Quality of Peach Trees by Means of the QualiTree Model.

Science.gov (United States)

Rahmati, Mitra; Mirás-Avalos, José M; Valsesia, Pierre; Lescourret, Françoise; Génard, Michel; Davarynejad, Gholam H; Bannayan, Mohammad; Azizi, Majid; Vercambre, Gilles

2018-01-01

Climate change projections predict warmer and drier conditions. In general, moderate to severe water stress reduce plant vegetative growth and leaf photosynthesis. However, vegetative and reproductive growths show different sensitivities to water deficit. In fruit trees, water restrictions may have serious implications not only on tree growth and yield, but also on fruit quality, which might be improved. Therefore, it is of paramount importance to understand the complex interrelations among the physiological processes involved in within-tree carbon acquisition and allocation, water uptake and transpiration, organ growth, and fruit composition when affected by water stress. This can be studied using process-based models of plant functioning, which allow assessing the sensitivity of various physiological processes to water deficit and their relative impact on vegetative growth and fruit quality. In the current study, an existing fruit-tree model (QualiTree) was adapted for describing the water stress effects on peach ( Prunus persica L. Batsch) vegetative growth, fruit size and composition. First, an energy balance calculation at the fruit-bearing shoot level and a water transfer formalization within the plant were integrated into the model. Next, a reduction function of vegetative growth according to tree water status was added to QualiTree. Then, the model was parameterized and calibrated for a late-maturing peach cultivar ("Elberta") under semi-arid conditions, and for three different irrigation practices. Simulated vegetative and fruit growth variability over time was consistent with observed data. Sugar concentrations in fruit flesh were well simulated. Finally, QualiTree allowed for determining the relative importance of photosynthesis and vegetative growth reduction on carbon acquisition, plant growth and fruit quality under water constrains. According to simulations, water deficit impacted vegetative growth first through a direct effect on its sink strength

Are trees long-lived?

Science.gov (United States)

Kevin T. Smith

2009-01-01

Trees and tree care can capture the best of people's motivations and intentions. Trees are living memorials that help communities heal at sites of national tragedy, such as Oklahoma City and the World Trade Center. We mark the places of important historical events by the trees that grew nearby even if the original tree, such as the Charter Oak in Connecticut or...

Gravitino Dark Matter in Tree Level Gauge Mediation with and without R-parity

DEFF Research Database (Denmark)

Arcadi, G.; Di Luzio, L.; Nardecchia, M.

2011-01-01

We investigate the cosmological aspects of Tree Level Gauge Mediation, a recently proposed mechanism in which the breaking of supersymmetry is communicated to the soft scalar masses by extra gauge interactions at the tree level. Embedding the mechanism in a Grand Unified Theory and requiring...... the observability of sfermion masses at the Large Hadron Collider, it follows that the Lightest Supersymmetric Particle is a gravitino with a mass of the order of 10 GeV. The analysis in the presence of R-parity shows that a typical Tree Level Gauge Mediation spectrum leads to an overabundance of the Dark Matter...... operators. We finally analyze the cosmological implications of this setup by identifying the phenomenologically viable regions of the parameter space....

Simulation and statistical analysis for the optimization of nitrogen liquefaction plant with cryogenic Claude cycle using process modeling tool: ASPEN HYSYS

International Nuclear Information System (INIS)

Joshi, D.M.

2017-01-01

Cryogenic technology is used for liquefaction of many gases and it has several applications in food process engineering. Temperatures below 123 K are considered to be in the field of cryogenics. Extreme low temperatures are a basic need for many industrial processes and have several applications, such as superconductivity of magnets, space, medicine and gas industries. Several methods can be used to obtain the low temperatures required for liquefaction of gases. The process of cooling or refrigerating a gas to a temperature below its critical temperature so that liquid can be formed at some suitable pressure, which is below the critical pressure, is the basic liquefaction process. Different cryogenic cycle configurations are designed for getting the liquefied form of gases at different temperatures. Each of the cryogenic cycles like Linde cycle, Claude cycle, Kapitza cycle or modified Claude cycle has its own advantages and disadvantages. The placement of heat exchangers, Joule-Thompson valve and turboexpander decides the configuration of a cryogenic cycle. Each configuration has its own efficiency according to the application. Here, a nitrogen liquefaction plant is used for the analysis purpose. The process modeling tool ASPEN HYSYS can provide a software simulation approach before the actual implementation of the plant in the field. This paper presents the simulation and statistical analysis of the Claude cycle with the process modeling tool ASPEN HYSYS. It covers the technique used to optimize the liquefaction of the plant. The simulation results so obtained can be used as a reference for the design and optimization of the nitrogen liquefaction plant. Efficient liquefaction will give the best performance and productivity to the plant.

Simulation and statistical analysis for the optimization of nitrogen liquefaction plant with cryogenic Claude cycle using process modeling tool: ASPEN HYSYS

Science.gov (United States)

Joshi, D. M.

2017-09-01

Cryogenic technology is used for liquefaction of many gases and it has several applications in food process engineering. Temperatures below 123 K are considered to be in the field of cryogenics. Extreme low temperatures are a basic need for many industrial processes and have several applications, such as superconductivity of magnets, space, medicine and gas industries. Several methods can be used to obtain the low temperatures required for liquefaction of gases. The process of cooling or refrigerating a gas to a temperature below its critical temperature so that liquid can be formed at some suitable pressure, which is below the critical pressure, is the basic liquefaction process. Different cryogenic cycle configurations are designed for getting the liquefied form of gases at different temperatures. Each of the cryogenic cycles like Linde cycle, Claude cycle, Kapitza cycle or modified Claude cycle has its own advantages and disadvantages. The placement of heat exchangers, Joule-Thompson valve and turboexpander decides the configuration of a cryogenic cycle. Each configuration has its own efficiency according to the application. Here, a nitrogen liquefaction plant is used for the analysis purpose. The process modeling tool ASPEN HYSYS can provide a software simulation approach before the actual implementation of the plant in the field. This paper presents the simulation and statistical analysis of the Claude cycle with the process modeling tool ASPEN HYSYS. It covers the technique used to optimize the liquefaction of the plant. The simulation results so obtained can be used as a reference for the design and optimization of the nitrogen liquefaction plant. Efficient liquefaction will give the best performance and productivity to the plant.

There's Life in Hazard Trees

Science.gov (United States)

Mary Torsello; Toni McLellan

The goals of hazard tree management programs are to maximize public safety and maintain a healthy sustainable tree resource. Although hazard tree management frequently targets removal of trees or parts of trees that attract wildlife, it can take into account a diversity of tree values. With just a little extra planning, hazard tree management can be highly beneficial...

Fast Tree: Computing Large Minimum-Evolution Trees with Profiles instead of a Distance Matrix

Energy Technology Data Exchange (ETDEWEB)

N. Price, Morgan; S. Dehal, Paramvir; P. Arkin, Adam

2009-07-31

Gene families are growing rapidly, but standard methods for inferring phylogenies do not scale to alignments with over 10,000 sequences. We present FastTree, a method for constructing large phylogenies and for estimating their reliability. Instead of storing a distance matrix, FastTree stores sequence profiles of internal nodes in the tree. FastTree uses these profiles to implement neighbor-joining and uses heuristics to quickly identify candidate joins. FastTree then uses nearest-neighbor interchanges to reduce the length of the tree. For an alignment with N sequences, L sites, and a different characters, a distance matrix requires O(N^2) space and O(N^2 L) time, but FastTree requires just O( NLa + N sqrt(N) ) memory and O( N sqrt(N) log(N) L a ) time. To estimate the tree's reliability, FastTree uses local bootstrapping, which gives another 100-fold speedup over a distance matrix. For example, FastTree computed a tree and support values for 158,022 distinct 16S ribosomal RNAs in 17 hours and 2.4 gigabytes of memory. Just computing pairwise Jukes-Cantor distances and storing them, without inferring a tree or bootstrapping, would require 17 hours and 50 gigabytes of memory. In simulations, FastTree was slightly more accurate than neighbor joining, BIONJ, or FastME; on genuine alignments, FastTree's topologies had higher likelihoods. FastTree is available at http://microbesonline.org/fasttree.

TreeRipper web application: towards a fully automated optical tree recognition software

Directory of Open Access Journals (Sweden)

Hughes Joseph

2011-05-01

Full Text Available Abstract Background Relationships between species, genes and genomes have been printed as trees for over a century. Whilst this may have been the best format for exchanging and sharing phylogenetic hypotheses during the 20th century, the worldwide web now provides faster and automated ways of transferring and sharing phylogenetic knowledge. However, novel software is needed to defrost these published phylogenies for the 21st century. Results TreeRipper is a simple website for the fully-automated recognition of multifurcating phylogenetic trees (http://linnaeus.zoology.gla.ac.uk/~jhughes/treeripper/. The program accepts a range of input image formats (PNG, JPG/JPEG or GIF. The underlying command line c++ program follows a number of cleaning steps to detect lines, remove node labels, patch-up broken lines and corners and detect line edges. The edge contour is then determined to detect the branch length, tip label positions and the topology of the tree. Optical Character Recognition (OCR is used to convert the tip labels into text with the freely available tesseract-ocr software. 32% of images meeting the prerequisites for TreeRipper were successfully recognised, the largest tree had 115 leaves. Conclusions Despite the diversity of ways phylogenies have been illustrated making the design of a fully automated tree recognition software difficult, TreeRipper is a step towards automating the digitization of past phylogenies. We also provide a dataset of 100 tree images and associated tree files for training and/or benchmarking future software. TreeRipper is an open source project licensed under the GNU General Public Licence v3.

Energy-efficient multicast traffic grooming strategy based on light-tree splitting for elastic optical networks

Science.gov (United States)

Liu, Huanlin; Yin, Yarui; Chen, Yong

2017-07-01

In order to address the problem of optimizing the spectrum resources and power consumption in elastic optical networks (EONs), we investigate the potential gains by jointly employing the light-tree splitting and traffic grooming for multicast requests. An energy-efficient multicast traffic grooming strategy based on light-tree splitting (EED-MTGS-LS) is proposed in this paper. Firstly, we design a traffic pre-processing mechanism to decide the multicast requests' routing order, which considers the request's bandwidth requirement and physical hops synthetically. Then, by dividing a light-tree to some sub-light-trees and grooming the request to these sub-light-trees, the light-tree sharing ratios of multicast requests can be improved. What's more, a priority scheduling vector is constructed, which aims to improve the success rate of spectrum assignment for grooming requests. Finally, a grooming strategy is designed to optimize the total power consumption by reducing the use of transponders and IP routers during routing. Simulation results show that the proposed strategy can significantly improve the spectrum utilization and save the power consumption.

MixtureTree annotator: a program for automatic colorization and visual annotation of MixtureTree.

Directory of Open Access Journals (Sweden)

Shu-Chuan Chen

Full Text Available The MixtureTree Annotator, written in JAVA, allows the user to automatically color any phylogenetic tree in Newick format generated from any phylogeny reconstruction program and output the Nexus file. By providing the ability to automatically color the tree by sequence name, the MixtureTree Annotator provides a unique advantage over any other programs which perform a similar function. In addition, the MixtureTree Annotator is the only package that can efficiently annotate the output produced by MixtureTree with mutation information and coalescent time information. In order to visualize the resulting output file, a modified version of FigTree is used. Certain popular methods, which lack good built-in visualization tools, for example, MEGA, Mesquite, PHY-FI, TreeView, treeGraph and Geneious, may give results with human errors due to either manually adding colors to each node or with other limitations, for example only using color based on a number, such as branch length, or by taxonomy. In addition to allowing the user to automatically color any given Newick tree by sequence name, the MixtureTree Annotator is the only method that allows the user to automatically annotate the resulting tree created by the MixtureTree program. The MixtureTree Annotator is fast and easy-to-use, while still allowing the user full control over the coloring and annotating process.

On Determining if Tree-based Networks Contain Fixed Trees.

Science.gov (United States)

Anaya, Maria; Anipchenko-Ulaj, Olga; Ashfaq, Aisha; Chiu, Joyce; Kaiser, Mahedi; Ohsawa, Max Shoji; Owen, Megan; Pavlechko, Ella; St John, Katherine; Suleria, Shivam; Thompson, Keith; Yap, Corrine

2016-05-01

We address an open question of Francis and Steel about phylogenetic networks and trees. They give a polynomial time algorithm to decide if a phylogenetic network, N, is tree-based and pose the problem: given a fixed tree T and network N, is N based on T? We show that it is [Formula: see text]-hard to decide, by reduction from 3-Dimensional Matching (3DM) and further that the problem is fixed-parameter tractable.

Whole-tree distribution and temporal variation of non-structural carbohydrates in broadleaf evergreen trees.

Science.gov (United States)

Smith, Merryn G; Miller, Rebecca E; Arndt, Stefan K; Kasel, Sabine; Bennett, Lauren T

2018-04-01

Non-structural carbohydrates (NSCs) form a fundamental yet poorly quantified carbon pool in trees. Studies of NSC seasonality in forest trees have seldom measured whole-tree NSC stocks and allocation among organs, and are not representative of all tree functional types. Non-structural carbohydrate research has primarily focussed on broadleaf deciduous and coniferous evergreen trees with distinct growing seasons, while broadleaf evergreen trees remain under-studied despite their different growth phenology. We measured whole-tree NSC allocation and temporal variation in Eucalyptus obliqua L'Hér., a broadleaf evergreen tree species typically occurring in mixed-age temperate forests, which has year-round growth and the capacity to resprout after fire. Our overarching objective was to improve the empirical basis for understanding the functional importance of NSC allocation and stock changes at the tree- and organ-level in this tree functional type. Starch was the principal storage carbohydrate and was primarily stored in the stem and roots of young (14-year-old) trees rather than the lignotuber, which did not appear to be a specialized starch storage organ. Whole-tree NSC stocks were depleted during spring and summer due to significant decreases in starch mass in the roots and stem, seemingly to support root and crown growth but potentially exacerbated by water stress in summer. Seasonality of stem NSCs differed between young and mature trees, and was not synchronized with stem basal area increments in mature trees. Our results suggest that the relative magnitude of seasonal NSC stock changes could vary with tree growth stage, and that the main drivers of NSC fluctuations in broadleaf evergreen trees in temperate biomes could be periodic disturbances such as summer drought and fire, rather than growth phenology. These results have implications for understanding post-fire tree recovery via resprouting, and for incorporating NSC pools into carbon models of mixed

The effect of contaminated groundwater on tree growth: A tree-ring analysis

International Nuclear Information System (INIS)

LeBlanc, D.C.; Loehle, C.

1990-10-01

A study was conducted on the effect of contaminated groundwater seepage on tree growth downslope from F- and H-Area seepage basins of the Savannah River Site. Trees in wetlands along Four Mile Creek began to show localized stress and mortality in the late 1970s. Extreme winter temperatures and high rainfall were ruled out as potential causal factors of tree stress. Drought was shown to affect trees in both contaminated and uncontaminated zones, but trees in uncontaminated areas exhibit better recovery after drought than trees in contaminated areas. Pollution-mediated alteration of soil acidity and aluminum, sodium, and heavy metal concentrations likely acted to predispose trees to decline, with severe drought acting as the trigger for decline initiation and tree death. Thus, a moderate pollution loading, not sufficient to cause visible damage of itself, may create conditions in which sudden, severe decline could result from natural stresses. This mechanism of forest decline is common, and should be considered in evaluations of the impact of pollution on wetland forest systems. 28 refs., 4 figs., 6 tabs

SILVA tree viewer: interactive web browsing of the SILVA phylogenetic guide trees.

Science.gov (United States)

Beccati, Alan; Gerken, Jan; Quast, Christian; Yilmaz, Pelin; Glöckner, Frank Oliver

2017-09-30

Phylogenetic trees are an important tool to study the evolutionary relationships among organisms. The huge amount of available taxa poses difficulties in their interactive visualization. This hampers the interaction with the users to provide feedback for the further improvement of the taxonomic framework. The SILVA Tree Viewer is a web application designed for visualizing large phylogenetic trees without requiring the download of any software tool or data files. The SILVA Tree Viewer is based on Web Geographic Information Systems (Web-GIS) technology with a PostgreSQL backend. It enables zoom and pan functionalities similar to Google Maps. The SILVA Tree Viewer enables access to two phylogenetic (guide) trees provided by the SILVA database: the SSU Ref NR99 inferred from high-quality, full-length small subunit sequences, clustered at 99% sequence identity and the LSU Ref inferred from high-quality, full-length large subunit sequences. The Tree Viewer provides tree navigation, search and browse tools as well as an interactive feedback system to collect any kinds of requests ranging from taxonomy to data curation and improving the tool itself.