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Sample records for annual growth rings

  1. Occurrence of annual growth rings in Rhizophora mangle in a region with low climate seasonality.

    PubMed

    Souza, Brunna T; Estrada, Gustavo C D; Soares, Mário L G; Callado, Cátia H

    2016-01-01

    The formation of annual growth rings has been confirmed for several mangrove species in the last decade, among which is the Rhizophora mangle. However, the record of annual rings for this species was made in a region with high hydric seasonality, a widely recognized induction factor of annual rings in tropical species. In this sense, the present study aimed to verify the occurrence of annual growth rings in R. mangle in the mangroves of Guaratiba (Rio de Janeiro, Southeastern Brazil), a region with low hydric seasonality. For this purpose, the crossdating technique was applied in ten trees collected with known age (seven years). The growth rings are characterized by alternating layers of low vessel density (earlywood) and high vessel density (latewood). Multiple regression analysis indicated that growth rings width variation is driven by precipitation, water surplus, water deficit and water storage. Crossdating analysis confirmed the existence of annual growth rings in the R. mangle in Guaratiba. This discovery in a region with low hydric seasonality increases the dendrocronological potential of this species and suggests the importance of biological factors (eg. phenological behavior) as complementary inductors for the formation of growth rings in this species. PMID:27142552

  2. Radiocarbon evidence for annual growth rings in a deep sea octocoral (Primnoa resedaeformis)

    SciTech Connect

    Sherwood, O A; Scott, D B; Risk, M J; Guilderson, T P

    2005-04-05

    The deep-sea gorgonian octocoral Primnoa resedaeformis is distributed throughout the Atlantic and Pacific Oceans at depths of 65-3200 m. It has a two-part skeleton of calcite and gorgonin. Towards the inside of the axial skeleton gorgonin and calcite are deposited in concentric growth rings, similar to tree rings. Colonies were collected from the Northeast Channel (northwest Atlantic Ocean, southwest of Nova Scotia, Canada) from depths of 250-475 m. Radiocarbon was measured in individual rings isolated from sections of each colony, after dissolution of calcite. Each {Delta}{sup 14}C measurement was paired with a ring age determined by three amateur ring counters. The precision of ring counts averaged better than {+-} 2 years. Accurate reconstruction of 20th century bomb-radiocarbon shows that (1) the growth rings are formed annually, (2) the gorgonin is derived from surface particulate organic matter (POM) and (3) useful environmental data are recorded in the organic endoskeletons of deep-sea octocorals. These results support the use of Primnoa resedaeformis as a long-term, high resolution monitor of surface ocean conditions, particularly in temperate and boreal environments where proxy data are lacking.

  3. The suitability of annual tree growth rings as environmental archives: Evidence from Sr, Nd, Pb and Ca isotopes in spruce growth rings from the Strengbach watershed

    NASA Astrophysics Data System (ADS)

    Stille, Peter; Schmitt, Anne-Désirée; Labolle, François; Pierret, Marie-Claire; Gangloff, Sophie; Cobert, Florian; Lucot, Eric; Guéguen, Florence; Brioschi, Laure; Steinmann, Marc; Chabaux, François

    2012-05-01

    The combination of the Sr, Nd and Pb isotope systems, recognized as tracers of sources, with the Ca isotope system, known to reveal biology-related fractionations, allowed us to test the reliability of spruce (Picea abies) growth rings as environmental archives through time (from 1916 to 1983) in a forest ecosystem affected by acid atmospheric deposition. Sr and Pb isotopes have already been applied in former tree-ring studies, whereas the suitability of Nd and Ca isotope systems is checked in the present article. Our Sr and Nd isotope data indicate an evolution in the cation origin with a geogenic origin for the oldest rings and an atmospheric origin for the youngest rings. Ca isotopes show, for their part, an isotopic homogeneity which could be linked to the very low weathering flux of Ca. Since this flux is weak the spruces' root systems have pumped the Ca mainly from the organic matter-rich top-soil over the past century. In contrast, the annual growth rings studied are not reliable and suitable archives of past Pb pollution.

  4. An ecological study on air pollution: Changes in annual ring growth of the Japanese cedar and prevalence of respiratory symptoms in schoolchildren in Japanese rural districts

    SciTech Connect

    Kagamimori, S.; Katoh, T.; Naruse, Y.; Kakiuchi, H.; Matsubara, I.; Kasuya, M.; Kawano, S. )

    1990-06-01

    The effect of air pollution caused by oil-fired electricity-generating stations on the annual ring growth of the Japanese cedar (Cryptomeria japonica, D. Don) and prevalence of respiratory symptoms in schoolchildren were investigated. By retrospective analysis the annual ring growth has been demonstrated to show good agreement with the general trend in air pollution. In addition it was found to be related to the prevalence of respiratory symptoms. The reduction in annual ring growth and increase in the prevalence of respiratory symptoms followed a deterioration in air pollution. Following upgrading of the power station and an improvement in air pollution, the annual ring growth and prevalence of respiratory symptoms showed opposite changes, respectively. Concerning the latter, the prevalence of wheezing and respiratory symptoms associated with school absence in schoolchildren with a positive skin test to house dust extract showed a closer correlation with the annual ring growth when compared with those who had never had a positive skin test.

  5. Fluctuations of cambial activity in relation to precipitation result in annual rings and intra-annual growth zones of xylem and phloem in teak (Tectona grandis) in Ivory Coast

    PubMed Central

    Dié, Agathe; Kitin, Peter; Kouamé, François N'Guessan; Van den Bulcke, Jan; Van Acker, Joris; Beeckman, Hans

    2012-01-01

    Background and Aims Teak forms xylem rings that potentially carry records of carbon sequestration and climate in the tropics. These records are only useful when the structural variations of tree rings and their periodicity of formation are known. Methods The seasonality of ring formation in mature teak trees was examined via correlative analysis of cambial activity, xylem and phloem formation, and climate throughout 1·5 years. Xylem and phloem differentiation were visualized by light microscopy and scanning electron microscopy. Key Results A 3 month dry season resulted in semi-deciduousness, cambial dormancy and formation of annual xylem growth rings (AXGRs). Intra-annual xylem and phloem growth was characterized by variable intensity. Morphometric features of cambium such as cambium thickness and differentiating xylem layers were positively correlated. Cambium thickness was strongly correlated with monthly rainfall (R2 = 0·7535). In all sampled trees, xylem growth zones (XGZs) were formed within the AXGRs during the seasonal development of new foliage. When trees achieved full leaf, the xylem in the new XGZs appeared completely differentiated and functional for water transport. Two phloem growth rings were formed in one growing season. Conclusions The seasonal formation pattern and microstructure of teak xylem suggest that AXGRs and XGZs can be used as proxies for analyses of the tree history and climate at annual and intra-annual resolution. PMID:22805529

  6. Annual Growth Bands in Hymenaea courbaril

    SciTech Connect

    Westbrook, J A; Guilderson, T P; Colinvaux, P A

    2004-02-09

    One significant source of annual temperature and precipitation data arises from the regular annual secondary growth rings of trees. Several tropical tree species are observed to form regular growth bands that may or may not form annually. Such growth was observed in one stem disk of the tropical legume Hymenaea courbaril near the area of David, Panama. In comparison to annual reference {Delta}{sup 14}C values from wood and air, the {Delta}{sup 14}C values from the secondary growth rings formed by H. courbaril were determined to be annual in nature in this one stem disk specimen. During this study, H. courbaril was also observed to translocate recently produced photosynthate into older growth rings as sapwood is converted to heartwood. This process alters the overall {Delta}{sup 14}C values of these transitional growth rings as cellulose with a higher {Delta}{sup 14}C content is translocated into growth rings with a relatively lower {Delta}{sup 14}C content. Once the annual nature of these growth rings is established, further stable isotope analyses on H. courbaril material in other studies may help to complete gaps in the understanding of short and of long term global climate patterns.

  7. Directional variance analysis of annual rings

    NASA Astrophysics Data System (ADS)

    Kumpulainen, P.; Marjanen, K.

    2010-07-01

    The wood quality measurement methods are of increasing importance in the wood industry. The goal is to produce more high quality products with higher marketing value than is produced today. One of the key factors for increasing the market value is to provide better measurements for increased information to support the decisions made later in the product chain. Strength and stiffness are important properties of the wood. They are related to mean annual ring width and its deviation. These indicators can be estimated from images taken from the log ends by two-dimensional power spectrum analysis. The spectrum analysis has been used successfully for images of pine. However, the annual rings in birch, for example are less distinguishable and the basic spectrum analysis method does not give reliable results. A novel method for local log end variance analysis based on Radon-transform is proposed. The directions and the positions of the annual rings can be estimated from local minimum and maximum variance estimates. Applying the spectrum analysis on the maximum local variance estimate instead of the original image produces more reliable estimate of the annual ring width. The proposed method is not limited to log end analysis only. It is usable in other two-dimensional random signal and texture analysis tasks.

  8. Climatic response of annual tree-rings

    NASA Astrophysics Data System (ADS)

    Ageev, Boris G.; Gruzdev, Aleksandr N.; Ponomarev, Yurii N.; Sapozhnikova, Valeria A.

    2014-11-01

    Extensive literature devoted to investigations into the influence of environmental conditions on the plant respiration and respiration rate. It is generally accepted that the respired CO2 generated in a stem completely diffuses into the atmosphere. Results obtained from explorations into the CO2 content in disc tree rings by the method proposed in this work shows that a major part of CO2 remains in tree stems and exhibits inter-annual variability. Different methods are used to describe of CO2 and H2O distributions in disc tree rings. The relation of CO2 and H2O variations in a Siberian stone pine disc to meteorological parameters are analyzed with use of wavelet, spectral and cross-spectral techniques. According to a multiple linear regression model, the time evolution of the width of Siberian stone pine rings can be partly explained by a combined influence of air temperature, precipitation, cloudiness and solar activity. Conclusions are made regarding the response of the CO2 and H2O content in coniferous tree disc rings to various climatic factors. Suggested method of CO2, (CO2+H2O) detection can be used for studying of a stem respiration in ecological risk areas.

  9. Validating the Assumption of Annual Shell Ring Deposition in Freshwater Mussels

    NASA Astrophysics Data System (ADS)

    Commens, A. M.; Haag, W. R.

    2005-05-01

    We evaluated the assumption of annual shell ring deposition by freshwater mussels in three rivers (Little Tallahatchie, Mississippi, 2000 and 2003; Sipsey, Alabama, 2000; St. Frances, Arkansas, 2003) using 14 species (Amblema plicata, Elliptio arca, Fusconaia cerina, F. flava, Lampsilis cardium, L. teres, Leptodea fragilis, Obliquaria reflexa, Potamilus purpuratus, Quadrula asperata, Q. pustulosa, Q. quadrula, Q, rumphiana, Tritogonia verrucosa). In 2000 we filed a notch in the shell margin, returned animals to the water, and retrieved them one year later. In 2003 we measured shell length and affixed numbered tags, returned animals to the water, and retrieved them one year later. After retrieval, we examined external and internal shell rings using thin-sections. For both methods, all species at all sites grew and deposited a single winter rest line between times of initial and final collection. Handling produced a conspicuous disturbance ring in all species. Characteristics of annual rings, disturbance rings, and false annuli differed qualitatively. Growth of some individuals was reduced after handling but negative growth occurred only in a few large individuals. Annual shell ring formation occurs consistently across species, space, and time. Formation of disturbance rings associated with collection indicates that mussels are extremely sensitive to handling.

  10. Past break-monsoon conditions detectable by high resolution intra-annual δ18O analysis of teak rings

    NASA Astrophysics Data System (ADS)

    Managave, S. R.; Sheshshayee, M. S.; Borgaonkar, H. P.; Ramesh, R.

    2010-03-01

    Intra-annual variations in the cellulose oxygen isotopic composition (δ18O) of several annual growth rings of three teak (Tectona grandis L.F.) trees from central India show a clear seasonal cycle with higher values in the early and late growing seasons and lower values in the middle. This cycle is useful to identify growth occurring during different phases of the growing season. Relative humidity (RH) appears to control the intra-annual δ18O variations rather than rainfall, and therefore past break-monsoon conditions associated with lower RH, could be detected by high resolution sub-sampling of annual rings for δ18O analysis.

  11. A test of "Annual resolution" in stalagmites using tree rings

    USGS Publications Warehouse

    Betancourt, J.L.; Grissino-Mayer, H. D.; Salzer, M.W.; Swetnam, T.W.

    2002-01-01

    So-called annual banding has been identified in a number of speleothems in which the number of bands approximates the time interval between successive U-series dates. The apparent annual resolution of speleothem records, however, remains largely untested. Here we statistically compare variations in band thickness from a late Holocene stalagmite in Carlsbad Cavern, Southern New Mexico, USA, with three independent tree-ring chronologies form the same region. We found no correspondence. Although there may be various explanations for the discordance, this limited exercise suggests that banded stalagmites should be held to the same rigorous standards in chronology building and climatic inference as annually resolved tree rings, corals, and ice cores. ?? 2002 University of Washington.

  12. Trees annual rings and "Sun-Climate" connection

    NASA Astrophysics Data System (ADS)

    Komitov, Boris; Duchlev, Peter; Bjandov, Georgy; Kirilova, Daniela

    The subject of the present work is an investigation of the relationship "Sun-Climate" for the territory of Central Bulgaria for the period from the end of 18th to the beginning of 21st century, based on dendro-chronoligical data. For this purpose the smoothed time series of the widths of annual rings of two beech samples from the region of Central Balkan Range are used. Special attention is paid to the 22 yr oscillations in the growth of tree mass and the relationship between the oscillation amplitude and the phase of solar cycles with sub-century and two-century duration. It is shown that the attenuation of 20-22 yr magnetic solar cycle during the hyper-centurial Dalton minimum (1795-1825/1830) is accompanied by strong drying and warming of the summers in Central Southern Bulgaria during this time. The onset of new Dalton-type hyper-centurial minimum in the beginning of the 21st century corresponds to an analogous climatic situation.

  13. The Annual North American Dendroecological Fieldweek: A workweek in applied tree-ring research

    SciTech Connect

    Brown, P.M.; Krusic, P.J.

    1995-12-31

    Trees record many events or processes that influence annual growth patterns. Dendrochronology is concerned with how environment and physiology affect tree growth as recorded within tree rings. The most basic principle of dendrochronology is that of crossdating, in which calendrical years are assigned to individual rings within a tree. Once crossdated, each ring is then a reflection of the climate or other environmental conditions that influenced that tree for that year. The Annual North American Dendroecological Fieldweek is a workweek in applied tree-ring research, designed to give both beginners to the discipline an introduction to its basic methodology and applications and more experienced users a change to work with and learn from others in the field in an informal group setting. The Fieldweek has had an outstanding history to date, with almost 250 participants in the five Fieldweeks from 1990 to 1994. The 6th Fieldweek is scheduled for 30 June to 8 July, 1995, at the Kananaskis Field Station in the Canadian Rockies near Calgary, Alberta.

  14. Growth cessation uncouples isotopic signals in leaves and tree rings of drought-exposed oak trees.

    PubMed

    Pflug, Ellen E; Siegwolf, R; Buchmann, N; Dobbertin, M; Kuster, T M; Günthardt-Goerg, M S; Arend, M

    2015-10-01

    An increase in temperature along with a decrease in summer precipitation in Central Europe will result in an increased frequency of drought events and gradually lead to a change in species composition in forest ecosystems. In the present study, young oaks (Quercus robur L. and Quercus petraea (Matt.) Liebl.) were transplanted into large mesocosms and exposed for 3 years to experimental warming and a drought treatment with yearly increasing intensities. Carbon and oxygen isotopic (δ(13)C and δ(18)O) patterns were analysed in leaf tissue and tree-ring cellulose and linked to leaf physiological measures and tree-ring growth. Warming had no effect on the isotopic patterns in leaves and tree rings, while drought increased δ(18)O and δ(13)C. Under severe drought, an unexpected isotopic pattern, with a decrease in δ(18)O, was observed in tree rings but not in leaves. This decrease in δ(18)O could not be explained by concurrent physiological analyses and is not supported by current physiological knowledge. Analysis of intra-annual tree-ring growth revealed a drought-induced growth cessation that interfered with the record of isotopic signals imprinted on recently formed leaf carbohydrates. This missing record indicates isotopic uncoupling of leaves and tree rings, which may have serious implications for the interpretation of tree-ring isotopes, particularly from trees that experienced growth-limiting stresses. PMID:26377873

  15. Annual growth bands in Hymenaea courbaril: implications for utilization in tropical paleoclimate reconstructions.

    NASA Astrophysics Data System (ADS)

    Westbrook, J. A.; Guilderson, T.; Colinvaux, P. A.; D'Arrigo, R.

    2004-12-01

    Instrumental records of environmental variables such as temperature and precipitation are necessary to understand climate patterns and variability. In general, such observations from the tropics do not exist prior to the late 19th century, and existing records contain large spatial and temporal gaps and are sparsely distributed. An important source of annual temperature and precipitation proxy-data comes from the regular annual growth rings of wood formed by trees. Tree growth rings occur in response to periodic seasonal changes in the environment. Although expansive and diverse in number and ecology, a vast majority of tropical trees do not produce distinct annual growth rings. Because of this, tropical dendrochronology and paleoclimate reconstructions have lagged behind their temperate and higher latitude cousins. Distinct secondary growth rings were investigated in a single individual of the tropical hardwood legume Hymenaea courbaril felled within the City of David, Republic of Panama. Rings that maintained circuitry were considered annual and were sampled for 14C. Radiocarbon values from the secondary growth rings from this specimen were compared with annual reference radiocarbon values from wood and air in North America, New Zealand and Germany. This comparison demonstrated that the secondary growth rings formed by H. courbaril were determined to be annual in nature in this one stem disk specimen. To confirm the consistency of the annual nature of the secondary growth rings in H. courbaril, nine (9) additional specimens were recovered from the small hamlet of San Carlos y Algarobbo in western Panama between the town of David and the cordillera approximately ~30km from the site of the first tree sample. Of the nine specimens, four were chosen for ring counts and isotope analyses. "Annual" rings were counted and samples corresponding to the equivalent time of the bomb-14C peak were sampled. In addition a small subset of years within one tree specimen were sub-annually

  16. Parameterization of tree-ring growth in Siberia

    NASA Astrophysics Data System (ADS)

    Tychkov, Ivan; Popkova, Margarita; Shishov, Vladimir; Vaganov, Eugene

    2016-04-01

    No doubt, climate-tree growth relationship is an one of the useful and interesting subject of studying in dendrochronology. It provides an information of tree growth dependency on climatic environment, but also, gives information about growth conditions and whole tree-ring growth process for long-term periods. New parameterization approach of the Vaganov-Shashkin process-based model (VS-model) is developed to described critical process linking climate variables with tree-ring formation. The approach (co-called VS-Oscilloscope) is presented as a computer software with graphical interface. As most process-based tree-ring models, VS-model's initial purpose is to describe variability of tree-ring radial growth due to variability of climatic factors, but also to determinate principal factors limiting tree-ring growth. The principal factors affecting on the growth rate of cambial cells in the VS-model are temperature, day light and soil moisture. Detailed testing of VS-Oscilloscope was done for semi-arid area of southern Siberia (Khakassian region). Significant correlations between initial tree-ring chronologies and simulated tree-ring growth curves were obtained. Direct natural observations confirm obtained simulation results including unique growth characteristic for semi-arid habitats. New results concerning formation of wide and narrow rings under different climate conditions are considered. By itself the new parameterization approach (VS-oscilloscope) is an useful instrument for better understanding of various processes in tree-ring formation. The work was supported by the Russian Science Foundation (RSF # 14-14-00219).

  17. Relating tree growth to rainfall in Bolivian rain forests: a test for six species using tree ring analysis.

    PubMed

    Brienen, Roel J W; Zuidema, Pieter A

    2005-11-01

    Many tropical regions show one distinct dry season. Often, this seasonality induces cambial dormancy of trees, particularly if these belong to deciduous species. This will often lead to the formation of annual rings. The aim of this study was to determine whether tree species in the Bolivian Amazon region form annual rings and to study the influence of the total amount and seasonal distribution of rainfall on diameter growth. Ring widths were measured on stem discs of a total of 154 trees belonging to six rain forest species. By correlating ring width and monthly rainfall data we proved the annual character of the tree rings for four of our study species. For two other species the annual character was proved by counting rings on trees of known age and by radiocarbon dating. The results of the climate-growth analysis show a positive relationship between tree growth and rainfall in certain periods of the year, indicating that rainfall plays a major role in tree growth. Three species showed a strong relationship with rainfall at the beginning of the rainy season, while one species is most sensitive to the rainfall at the end of the previous growing season. These results clearly demonstrate that tree ring analysis can be successfully applied in the tropics and that it is a promising method for various research disciplines. PMID:16012820

  18. Sensitivity of ring growth and carbon allocation to climatic variation vary within ponderosa pine trees.

    PubMed

    Kerhoulas, Lucy P; Kane, Jeffrey M

    2012-01-01

    Most dendrochronological studies focus on cores sampled from standard positions (main stem, breast height), yet vertical gradients in hydraulic constraints and priorities for carbon allocation may contribute to different growth sensitivities with position. Using cores taken from five positions (coarse roots, breast height, base of live crown, mid-crown branch and treetop), we investigated how radial growth sensitivity to climate over the period of 1895-2008 varies by position within 36 large ponderosa pines (Pinus ponderosa Dougl.) in northern Arizona. The climate parameters investigated were Palmer Drought Severity Index, water year and monsoon precipitation, maximum annual temperature, minimum annual temperature and average annual temperature. For each study tree, we generated Pearson correlation coefficients between ring width indices from each position and six climate parameters. We also investigated whether the number of missing rings differed among positions and bole heights. We found that tree density did not significantly influence climatic sensitivity to any of the climate parameters investigated at any of the sample positions. Results from three types of analyses suggest that climatic sensitivity of tree growth varied with position height: (i) correlations of radial growth and climate variables consistently increased with height; (ii) model strength based on Akaike's information criterion increased with height, where treetop growth consistently had the highest sensitivity and coarse roots the lowest sensitivity to each climatic parameter; and (iii) the correlation between bole ring width indices decreased with distance between positions. We speculate that increased sensitivity to climate at higher positions is related to hydraulic limitation because higher positions experience greater xylem tensions due to gravitational effects that render these positions more sensitive to climatic stresses. The low sensitivity of root growth to all climatic variables

  19. Graphene Layer Growth Chemistry: Five-Six-Ring Flip Reaction

    SciTech Connect

    Whitesides, R.; Domin, D.; Salomon-Ferrer, R.; Lester Jr., W.A.; Frenklach, M.

    2007-12-01

    Reaction pathways are presented for hydrogen-mediated isomerization of a five and six member carbon ring complex on the zigzag edge of a graphene layer. A new reaction sequence that reverses orientation of the ring complex, or 'flips' it, was identified. Competition between the flip reaction and 'ring separation' was examined. Ring separation is the reverse of the five and six member ring complex formation reaction, previously reported as 'ring collision'. The elementary steps of the pathways were analyzed using density-functional theory (DFT). Rate coefficients were obtained by solution of the energy master equation and classical transition state theory utilizing the DFT energies, frequencies, and geometries. The results indicate that the flip reaction pathway dominates the separation reaction and should be competitive with other pathways important to the graphene zigzag edge growth in high temperature environments.

  20. Interpretation of tree-ring data with a model for primary production, carbon allocation and growth

    NASA Astrophysics Data System (ADS)

    Li, G.; Wang, H.; Harrison, S. P.; Prentice, I. C.

    2013-12-01

    We present a simple, generic model of annual tree growth, called ';T'. This model accepts input from a generic light-use efficiency model which is known to provide good simulations of terrestrial carbon exchange. The light-use efficiency model provides values for Gross Primary Production (GPP) per unit of absorbed photosynthetically active radiation (PAR). Absorbed PAR is estimated from the current leaf area. GPP is allocated to foliage, transport-tissue, and fine-root production and respiration, in such a way as to satisfy well-understood dimensional relationships. The result is a model that can represent both ontogenetic effects and the effects of environmental variations and trends on growth. The model has been applied to simulate ring-width series from multiple individual trees in temperature- and drought-limited contexts. Each tree is initialized at its actual diameter at the time when local climate records started. These records are used to drive the trees' subsequent growth. Realistic simulations of the pattern of interannual variability of ring-width are generated, and shown to relate statistically to climate. An upward trend in ring-width during 1958-2007 is shown to be present in the primary observations, and in the simulations; but not in the standard, detrended ring-width series. This approach combines two modelling approaches previously developed in the global carbon cycle and forest science literature respectively. Neither has been widely applied in the context of tree-ring based climate reconstruction. This combination of methods offers promise, however, because it could provide a way to sidestep several known problems. These include: reliance on correlations for the interpretation of ring-width variations in terms of climate; the necessity of detrending using empirical functions (which can remove trends caused by variations in the environment as well as those that are ontogenetic); and the difficulty of assessing effects of extrinsic, non

  1. Missing Rings, Synchronous Growth, and Ecological Disturbance in a 36-Year Pitch Pine (Pinus rigida) Provenance Study.

    PubMed

    Leland, Caroline; Hom, John; Skowronski, Nicholas; Ledig, F Thomas; Krusic, Paul J; Cook, Edward R; Martin-Benito, Dario; Martin-Fernandez, Javier; Pederson, Neil

    2016-01-01

    Provenance studies are an increasingly important analog for understanding how trees adapted to particular climatic conditions might respond to climate change. Dendrochronological analysis can illuminate differences among trees from different seed sources in terms of absolute annual growth and sensitivity to external growth factors. We analyzed annual radial growth of 567 36-year-old pitch pine (Pinus rigida Mill.) trees from 27 seed sources to evaluate their performance in a New Jersey Pine Barrens provenance experiment. Unexpectedly, missing rings were prevalent in most trees, and some years-1992, 1999, and 2006-had a particularly high frequency of missing rings across the plantation. Trees from local seed sources (<55 km away from the plantation) had a significantly smaller percentage of missing rings from 1980-2009 (mean: 5.0%), relative to northernmost and southernmost sources (mean: 9.3% and 7.9%, respectively). Some years with a high frequency of missing rings coincide with outbreaks of defoliating insects or dry growing season conditions. The propensity for missing rings synchronized annual variations in growth across all trees and might have complicated the detection of potential differences in interannual variability among seed sources. Average ring width was significantly larger in seed sources from both the southernmost and warmest origins compared to the northernmost and coldest seed sources in most years. Local seed sources had the highest average radial growth. Adaptation to local environmental conditions and disturbances might have influenced the higher growth rate found in local seed sources. These findings underscore the need to understand the integrative impact of multiple environmental drivers, such as disturbance agents and climate change, on tree growth, forest dynamics, and the carbon cycle. PMID:27182599

  2. Missing Rings, Synchronous Growth, and Ecological Disturbance in a 36-Year Pitch Pine (Pinus rigida) Provenance Study

    PubMed Central

    Leland, Caroline; Hom, John; Skowronski, Nicholas; Krusic, Paul J.; Cook, Edward R.; Martin-Benito, Dario; Martin-Fernandez, Javier; Pederson, Neil

    2016-01-01

    Provenance studies are an increasingly important analog for understanding how trees adapted to particular climatic conditions might respond to climate change. Dendrochronological analysis can illuminate differences among trees from different seed sources in terms of absolute annual growth and sensitivity to external growth factors. We analyzed annual radial growth of 567 36-year-old pitch pine (Pinus rigida Mill.) trees from 27 seed sources to evaluate their performance in a New Jersey Pine Barrens provenance experiment. Unexpectedly, missing rings were prevalent in most trees, and some years—1992, 1999, and 2006—had a particularly high frequency of missing rings across the plantation. Trees from local seed sources (<55 km away from the plantation) had a significantly smaller percentage of missing rings from 1980–2009 (mean: 5.0%), relative to northernmost and southernmost sources (mean: 9.3% and 7.9%, respectively). Some years with a high frequency of missing rings coincide with outbreaks of defoliating insects or dry growing season conditions. The propensity for missing rings synchronized annual variations in growth across all trees and might have complicated the detection of potential differences in interannual variability among seed sources. Average ring width was significantly larger in seed sources from both the southernmost and warmest origins compared to the northernmost and coldest seed sources in most years. Local seed sources had the highest average radial growth. Adaptation to local environmental conditions and disturbances might have influenced the higher growth rate found in local seed sources. These findings underscore the need to understand the integrative impact of multiple environmental drivers, such as disturbance agents and climate change, on tree growth, forest dynamics, and the carbon cycle. PMID:27182599

  3. Downsag calderas, ring faults, caldera sizes, and incremental caldera growth

    NASA Astrophysics Data System (ADS)

    Walker, G. P. L.

    1984-09-01

    According to present concepts, a caldera is a more or less circular volcanic depression larger than a crater which is caused by subsidence. It is commonly considered that the subsided mass consists of a block or blocks encircled by a ring fracture. Caldera collapse is generally correlated with a major explosive eruption. The present investigation is concerned with six features which do not conform well with the favored caldera model. Attention is given to downsagged calderas, the distribution of postcaldera vents in calderas, vent rings, the size of calderas and cauldrons, incremental caldera growth, and caldera-forming events. It is found that no single structural or genetic model applies to all calderas. Thus, the fact of subsidence may be the only common feature. It is pointed out that most known ring dikes occur in Precambrian crust. This may mean that the subsiding piston mechanism operates best where the crust is sufficiently rigid and strong.

  4. Tree growth inference and prediction from diameter censuses and ring widths.

    PubMed

    Clark, James S; Wolosin, Michael; Dietze, Michael; Ibáñez, Inés; LaDeau, Shannon; Welsh, Miranda; Kloeppel, Brian

    2007-10-01

    Estimation of tree growth is based on sparse observations of tree diameter, ring widths, or increments read from a dendrometer. From annual measurements on a few trees (e.g., increment cores) or sporadic measurements from many trees (e.g., diameter censuses on mapped plots), relationships with resources, tree size, and climate are extrapolated to whole stands. There has been no way to formally integrate different types of data and problems of estimation that result from (1) multiple sources of observation error, which frequently result in impossible estimates of negative growth, (2) the fact that data are typically sparse (a few trees or a few years), whereas inference is needed broadly (many trees over many years), (3) the fact that some unknown fraction of the variance is shared across the population, and (4) the fact that growth rates of trees within competing stands are not independent. We develop a hierarchical Bayes state space model for tree growth that addresses all of these challenges, allowing for formal inference that is consistent with the available data and the assumption that growth is nonnegative. Prediction follows directly, incorporating the full uncertainty from inference with scenarios for "filling the gaps" for past growth rates and for future conditions affecting growth. An example involving multiple species and multiple stands with tree-ring data and up to 14 years of tree census data illustrates how different levels of information at the tree and stand level contribute to inference and prediction. PMID:17974333

  5. Radial growth of an extended spoke in Saturn's B ring

    NASA Technical Reports Server (NTRS)

    Eplee, R. E., Jr.; Smith, B. A.

    1985-01-01

    An analysis is reported of the pattern of radial growth of an extended spoke observed in the Voyager 2 low-resolution Saturn ring 'movie'. The feature is atypical in that it orbits Saturn at the corotational rate for 1-1/2 hours after the onset of its formation and then undergoes a 40-min acceleration to sustained Keplerian velocities. A correlation between the dynamical phases and the radial growth modes of the spoke is observed, one that seems consistent with the plasma cloud model of spoke formation and evolution proposed by Goertz and Morfill (1983), taken in the limit of high charge density.

  6. Radial growth of an extended spoke in Saturn's B ring

    SciTech Connect

    Eplee, R.E.,JR.; Smith, B.A.

    1985-08-01

    An analysis is reported of the pattern of radial growth of an extended spoke observed in the Voyager 2 low-resolution Saturn ring movie. The feature is atypical in that it orbits Saturn at the corotational rate for 1-1/2 hours after the onset of its formation and then undergoes a 40-min acceleration to sustained Keplerian velocities. A correlation between the dynamical phases and the radial growth modes of the spoke is observed, one that seems consistent with the plasma cloud model of spoke formation and evolution proposed by Goertz and Morfill (1983), taken in the limit of high charge density. 13 references.

  7. Influence of wood density in tree-ring based annual productivity assessments and its errors in Norway spruce

    NASA Astrophysics Data System (ADS)

    Bouriaud, O.; Teodosiu, M.; Kirdyanov, A. V.; Wirth, C.

    2015-04-01

    Estimations of tree annual biomass increments are used by a variety of studies related to forest productivity or carbon fluxes. Biomass increment estimations can be easily obtained from diameter surveys or historical diameter reconstructions based on tree rings records. However, the biomass models rely on the assumption of a constant wood density. Converting volume increment into biomass also requires assumptions on the wood density. Wood density has been largely reported to vary both in time and between trees. In Norway spruce, wood density is known to increase with decreasing ring width. This could lead to underestimating the biomass or carbon deposition in bad years. The variations between trees of wood density has never been discussed but could also contribute to deviations. A modelling approach could attenuate these effects but will also generate errors. Here were developed a model of wood density variations in Norway spruce, and an allometric model of volume growth. We accounted for variations in wood density both between years and between trees, based on specific measurements. We compared the effects of neglecting each variation source on the estimations of annual biomass increment. We also assessed the errors of the biomass increment predictions at tree level, and of the annual productivity at plot level. Our results showed a partial compensation of the decrease in ring width in bad years by the increase in wood density. The underestimation of the biomass increment in those years reached 15%. The errors related to the use of an allometric model of volume growth were modest, around ±15%. The errors related to variations in wood density were much larger, the biggest component being the inter-tree variability. The errors in plot-level annual biomass productivity reached up to 40%, with a full account of all the error sources.

  8. Influence of wood density in tree-ring-based annual productivity assessments and its errors in Norway spruce

    NASA Astrophysics Data System (ADS)

    Bouriaud, O.; Teodosiu, M.; Kirdyanov, A. V.; Wirth, C.

    2015-10-01

    Estimations of tree annual biomass increments are used by a variety of studies related to forest productivity or carbon fluxes. Biomass increment estimations can be easily obtained from diameter surveys or historical diameter reconstructions based on tree rings' records. However, the biomass models rely on the assumption that wood density is constant. Converting volume increment into biomass also requires assumptions about the wood density. Wood density has been largely reported to vary both in time and between trees. In Norway spruce, wood density is known to increase with decreasing ring width. This could lead to underestimating the biomass or carbon deposition in bad years. The variations between trees of wood density have never been discussed but could also contribute to deviations. A modelling approach could attenuate these effects but will also generate errors. Here a model of wood density variations in Norway spruce, and an allometric model of volume growth were developed. We accounted for variations in wood density both between years and between trees, based on specific measurements. We compared the effects of neglecting each variation source on the estimations of annual biomass increment. We also assessed the errors of the biomass increment predictions at tree level, and of the annual productivity at plot level. Our results showed a partial compensation of the decrease in ring width in bad years by the increase in wood density. The underestimation of the biomass increment in those years reached 15 %. The errors related to the use of an allometric model of volume growth were modest, around ±15 %. The errors related to variations in wood density were much larger, the biggest component being the inter-tree variability. The errors in plot-level annual biomass productivity reached up to 40 %, with a full account of all the error sources.

  9. Simulation of tree ring-widths with a model for primary production, carbon allocation and growth

    NASA Astrophysics Data System (ADS)

    Li, G.; Harrison, S. P.; Prentice, I. C.; Falster, D.

    2014-07-01

    We present a simple, generic model of annual tree growth, called "T". This model accepts input from a first-principles light-use efficiency model (the P model). The P model provides values for Gross Primary Production (GPP) per unit of absorbed photosynthetically active radiation (PAR). Absorbed PAR is estimated from the current leaf area. GPP is allocated to foliage, transport-tissue, and fine root production and respiration, in such a way as to satisfy well-understood dimensional and functional relationships. Our approach thereby integrates two modelling approaches separately developed in the global carbon-cycle and forest-science literature. The T model can represent both ontogenetic effects (impact of ageing) and the effects of environmental variations and trends (climate and CO2) on growth. Driven by local climate records, the model was applied to simulate ring widths during 1958-2006 for multiple trees of Pinus koraiensis from the Changbai Mountain, northeastern China. Each tree was initialised at its actual diameter at the time when local climate records started. The model produces realistic simulations of the interannual variability in ring width for different age cohorts (young, mature, old). Both the simulations and observations show a significant positive response of tree-ring width to growing-season total photosynthetically active radiation (PAR0) and the ratio of actual to potential evapotranspiration (α), and a significant negative response to mean annual temperature (MAT). The slopes of the simulated and observed relationships with PAR0 and α are similar; the negative response to MAT is underestimated by the model. Comparison of simulations with fixed and changing atmospheric CO2 concentration shows that CO2 fertilization over the past 50 years is too small to be distinguished in the ring-width data given ontogenetic trends and interannual variability in climate.

  10. Simulation of tree-ring widths with a model for primary production, carbon allocation, and growth

    NASA Astrophysics Data System (ADS)

    Li, G.; Harrison, S. P.; Prentice, I. C.; Falster, D.

    2014-12-01

    We present a simple, generic model of annual tree growth, called "T". This model accepts input from a first-principles light-use efficiency model (the "P" model). The P model provides values for gross primary production (GPP) per unit of absorbed photosynthetically active radiation (PAR). Absorbed PAR is estimated from the current leaf area. GPP is allocated to foliage, transport tissue, and fine-root production and respiration in such a way as to satisfy well-understood dimensional and functional relationships. Our approach thereby integrates two modelling approaches separately developed in the global carbon-cycle and forest-science literature. The T model can represent both ontogenetic effects (the impact of ageing) and the effects of environmental variations and trends (climate and CO2) on growth. Driven by local climate records, the model was applied to simulate ring widths during the period 1958-2006 for multiple trees of Pinus koraiensis from the Changbai Mountains in northeastern China. Each tree was initialised at its actual diameter at the time when local climate records started. The model produces realistic simulations of the interannual variability in ring width for different age cohorts (young, mature, and old). Both the simulations and observations show a significant positive response of tree-ring width to growing-season total photosynthetically active radiation (PAR0) and the ratio of actual to potential evapotranspiration (α), and a significant negative response to mean annual temperature (MAT). The slopes of the simulated and observed relationships with PAR0 and α are similar; the negative response to MAT is underestimated by the model. Comparison of simulations with fixed and changing atmospheric CO2 concentration shows that CO2 fertilisation over the past 50 years is too small to be distinguished in the ring-width data, given ontogenetic trends and interannual variability in climate.

  11. Climate variability at the onset of the Younger Dryas as reflected in annually resolved tree-ring stable isotope chronologies

    NASA Astrophysics Data System (ADS)

    Pieper, H.; Helle, G.; Brauer, A.; Kaiser, K. F.; Miramont, C.

    2013-12-01

    The Younger Dryas interval during the Last Glacial Termination was an abrupt return to glacial-like conditions punctuating the transition to a warmer, interglacial climate. Despite recent advances in the layer counting of ice-core records of the termination, the timing and length of the Younger Dryas remain controversial. Late Glacial and early Holocene tree-ring chronologies are rare, however, they contain valuable information about past environmental conditions at annual time resolution. Changes in tree-ring growth rates can be related to past climate anomalies and changes in the carbon and oxygen isotope composition of tree-ring cellulose reflect atmospheric and hydrospheric changes. We are investigating a 860-year (13200 - 12340 cal BP) dated dendrochronological record of Late Glacial and Early Holocene chronologies of scots pine (Pinus sylvestris L.) from subfossil tree remnants from Barbiers River (Moyenne Durance, Southern French Alps), as well as from Swiss (Dättnau, Landikon and Gänziloh) sites. Dendro-ecological parameters, such as ring width and stable isotope variations (δ 13C und δ 18O) are used to infer past environmental conditions. We will present our first carbon and oxygen isotope records from tree rings reflecting the environmental changes at the Alleröd/Younger Dryas -transition.

  12. Long Tree-Ring Chronologies Provide Evidence of Recent Tree Growth Decrease in a Central African Tropical Forest

    PubMed Central

    Battipaglia, Giovanna; Zalloni, Enrica; Castaldi, Simona; Marzaioli, Fabio; Cazzolla- Gatti, Roberto; Lasserre, Bruno; Tognetti, Roberto; Marchetti, Marco; Valentini, Riccardo

    2015-01-01

    It is still unclear whether the exponential rise of atmospheric CO2 concentration has produced a fertilization effect on tropical forests, thus incrementing their growth rate, in the last two centuries. As many factors affect tree growth patterns, short -term studies might be influenced by the confounding effect of several interacting environmental variables on plant growth. Long-term analyses of tree growth can elucidate long-term trends of plant growth response to dominant drivers. The study of annual rings, applied to long tree-ring chronologies in tropical forest trees enables such analysis. Long-term tree-ring chronologies of three widespread African species were measured in Central Africa to analyze the growth of trees over the last two centuries. Growth trends were correlated to changes in global atmospheric CO2 concentration and local variations in the main climatic drivers, temperature and rainfall. Our results provided no evidence for a fertilization effect of CO2 on tree growth. On the contrary, an overall growth decline was observed for all three species in the last century, which appears to be significantly correlated to the increase in local temperature. These findings provide additional support to the global observations of a slowing down of C sequestration in the trunks of forest trees in recent decades. Data indicate that the CO2 increase alone has not been sufficient to obtain a tree growth increase in tropical trees. The effect of other changing environmental factors, like temperature, may have overridden the fertilization effect of CO2. PMID:25806946

  13. Looking for age-related growth decline in natural forests: unexpected biomass patterns from tree rings and simulated mortality

    USGS Publications Warehouse

    Foster, Jane R.; D'Amato, Anthony W.; Bradford, John B.

    2014-01-01

    Forest biomass growth is almost universally assumed to peak early in stand development, near canopy closure, after which it will plateau or decline. The chronosequence and plot remeasurement approaches used to establish the decline pattern suffer from limitations and coarse temporal detail. We combined annual tree ring measurements and mortality models to address two questions: first, how do assumptions about tree growth and mortality influence reconstructions of biomass growth? Second, under what circumstances does biomass production follow the model that peaks early, then declines? We integrated three stochastic mortality models with a census tree-ring data set from eight temperate forest types to reconstruct stand-level biomass increments (in Minnesota, USA). We compared growth patterns among mortality models, forest types and stands. Timing of peak biomass growth varied significantly among mortality models, peaking 20–30 years earlier when mortality was random with respect to tree growth and size, than when mortality favored slow-growing individuals. Random or u-shaped mortality (highest in small or large trees) produced peak growth 25–30 % higher than the surviving tree sample alone. Growth trends for even-aged, monospecific Pinus banksiana or Acer saccharum forests were similar to the early peak and decline expectation. However, we observed continually increasing biomass growth in older, low-productivity forests of Quercus rubra, Fraxinus nigra, and Thuja occidentalis. Tree-ring reconstructions estimated annual changes in live biomass growth and identified more diverse development patterns than previous methods. These detailed, long-term patterns of biomass development are crucial for detecting recent growth responses to global change and modeling future forest dynamics.

  14. [Paleoclimate of La Guajira, Colombia; by the growth rings of Capparis odoratissima (Capparidaceae)].

    PubMed

    Ramírez, Jorge Andrés; Ignacio del Valle, Jorge

    2011-09-01

    There is great concern about the effect of climate change in arid and subarid areas of the tropics. Climate change combined with other anthropogenic activities such as deforestation, fires and over-grazing can accelerate their degradation and, consequently, the increases in losses of biological and economic productivity. Climate models, both local and global, predict that rainfall in the arid Peninsula of La Guajira in the Colombian Caribbean would be reduced and temperature would be increased as a result of climate change. However, as there are only suitable climate records since 1972, it is not possible to verify if, indeed, this is happening. To try to verify the hypothesis of reducing rainfall and rising temperatures we developed a growth ring chronology of Capparis odoratissima in the Middle Peninsula of La Guajira with 17 trees and 45 series which attain 48 years back. We use standard dendrochronological methods that showed statistically significant linear relationship with local climatic variables such as air temperature, sea surface temperature (SST), annual precipitation and wind speed; we also reach to successful relationship of the chronology with global climatic variables as the indices SOI and MEI of the ENSO phenomenon. The transfer functions estimated with the time series (1955 and 2003) do not showed statistically significant trends, indicating that during this period of time the annual precipitation or temperatures have not changed. The annual nature of C. odoratissima growth rings, the possibility of cross-dated among the samples of this species, and the high correlation with local and global climatic variables indicate a high potential of this species for dendrochronological studies in this part of the American continent. PMID:22017140

  15. Regional climate pattern during two millennia estimated from annual tree rings of Yaku cedar trees: a hint for solar variability?

    NASA Astrophysics Data System (ADS)

    Muraki, Yasushi; Mitsutani, Takumi; Shibata, Shoichi; Kuramata, Syuichi; Masuda, Kimiaki; Nagaya, Kentaro

    2015-02-01

    We analyzed trees that have survived on Yaku island (Yakushima) for 2,000 years. Quite surprisingly, the Fourier and wavelet analyses of the annual growth rate identified 2 cycles of periodicities of 11 and (24 ± 4) years during the Oort, Wolf, Spörer, Maunder, and Dalton minima. The 11-year periodicity originated from solar activity, while the (24 ± 4)-year periodicity may be related to the Pacific Decadal Oscillation (PDO). In particular, we have discovered an 11-year periodicity in the meteorological daylight-hour data from Yakushima in the month of June during 1938 to 2013 and a 24-year periodicity in July. The growth rate of the tree rings may be affected by the variation of the daylight hour.

  16. A new serial pooling method of shifted tree ring blocks to construct millennia long tree ring isotope chronologies with annual resolution.

    PubMed

    Boettger, Tatjana; Friedrich, Michael

    2009-03-01

    The study presents a new serial pooling method of shifted tree ring blocks for the building of isotope chronologies. This method combines the advantages of traditional 'serial' and 'intertree' pooling, and can be recommended for the construction of sub-regional long isotope chronologies with sufficient replication, and on annual resolution, especially for the case of extremely narrow tree rings. For Scots pines (Pinus sylvestris L., Khibiny Low Mountains, NW Russia) and Silver firs (Abies alba Mill., Franconia, Southern Germany), serial pooling of five consecutive tree rings seems appropriate because the species- and site-specific particularities lead to blurs of climate linkages in their tree rings for the period up to ca. five years back. An equivalent to a five-year running means that curve gained on the base annual data sets of single trees can be derived from the analysis of yearly shifted five-year blocks of consecutive tree rings, and therefore, with approximately 20% of the expense. Good coherence of delta(13)C- and delta(18)O-values between calculated means of annual total rings or late wood data and means of five-year blocks of consecutive total tree rings analysed experimentally on most similar material confirms this assumption. PMID:19191128

  17. Graphene Layer Growth: Collision of Migrating Five-MemberRings

    SciTech Connect

    Whitesides, Russell; Kollias, Alexander C.; Domin, Dominik; Lester Jr., William A.; Frenklach, Michael

    2005-12-02

    A reaction pathway is explored in which two cyclopenta groups combine on the zigzag edge of a graphene layer. The process is initiated by H addition to a five-membered ring, followed by opening of that ring and the formation of a six-membered ring adjacent to another five-membered ring. The elementary steps of the migration pathway are analyzed using density functional theory to examine the region of the potential energy surface associated with the pathway. The calculations are performed on a substrate modeled by the zigzag edge of tetracene. Based on the obtained energetics, the dynamics of the system are analyzed by solving the energy transfer master equations. The results indicate energetic and reaction-rate similarity between the cyclopenta combination and migration reactions. Also examined in the present study are desorption rates of migrating cyclopenta rings which are found to be comparable to cyclopenta ring migration.

  18. [Anatomic characterization of growth-rings in 80 potential tree species for dendrocronological studies in the Central Forest, Perú].

    PubMed

    Beltrán Gutiérrez, Lizandro Adal; Valencia Ramos, Gina Mariela

    2013-09-01

    The knowledge about the existence of annual tree rings in tropical trees, which was already found at the beginning of the last century, was ignored by many scientists for a long time. Wood samples of 80 tree species from seven different sites belonging to Satipo and Chanchamayo provinces in Central Forest, Perú. Wood slices were taken at 1.30 m height, following the Peruvian Technical Norms (NTP) 251-008, COPANT norms 30:1-019 and IAWA (1989). Results showed that 24 of the 80 tree species analyzed showed a potential for dendrocronological studies, 25 had problems for growth-rings analysis, and 31 did not have potential. The problems most frequently found were: barely visible or irregular ring growth, parenchyma bands and multiseriate rays difficult to be identified in rings growth. The "T" Student test showed that the significant variation in vessel and fiber diameters between growth zones (Early-wood and late-wood) of species with potential for dendrocronology, do have a periodic cells production, so is possible to suggest the annual formation of each growth-ring. However, those species without potential to dendrocronology may be influenced by of a lot of factors, such as biotic and abiotic conditions of environment, as well as the genetic aspect of each species. PMID:24027905

  19. Ring chromosome 5 associated with severe growth retardation as the sole major physical abnormality

    SciTech Connect

    Migliori, M.V.; Pettinari, A.; Cherubini, V.; Bartolotta, E.; Pecora, R.

    1994-01-01

    The authors report on a case of ring chromosome 5 in a 36-month-old girl with severe growth retardation, clinodactyly, mild psychological abnormalities, and normal facial appearance. Endocrine tests showed partial growth hormone deficiency. Cytogenetic investigation failed to demonstrate any apparent microscopic deletion of either the short or long arm of chromosome 5 as a consequence of ring formation. In 12% of cells examined, the ring was either absent or present in multiple copies. Only 3 previous cases of ring chromosome 5 have been reported in association with short stature of prenatal onset and minor anomalies, without mental retardation. 12 refs., 3 figs.

  20. Tree-ring growth and wood chemistry response to manipulated precipitation variation for two temperate Quercus species

    SciTech Connect

    Wagner, Rebekah J.; Kaye, Margot W.; Abrams, Marc D.; Hanson, Paul J; Martin, Madhavi Z

    2012-01-01

    We examined the relationship among ambient and manipulated precipitation, wood chemistry, and their relationship with radial growth for two oak species in eastern Tennessee. The study took place on the Walker Branch Throughfall Displacement Experiment (TDE) site, located at the Oak Ridge National Laboratory in Oak Ridge, TN. Two dominant species, white oak (Quercus alba) and chestnut oak (Quercus prinus), were selected for study from a 13-year experiment of whole-stand precipitation manipulation (wet, ambient and dry). The relationships between tree-ring width and climate were compared for both species to determine the impact of precipitation manipulations on ring width index. This study used experimental spectroscopy techniques to measure the sensitivity of tree-ring responses to directional changes in precipitation over 13 years, and the results suggest that oaks at this study site are resilient to imposed changes, but sensitive to inter-annual variations in climate. Laser-induced breakdown spectroscopy (LIBS) allowed us to measure nutrient intensities (similar to element concentrations) at 0.5-1.0 mm spacing along the radial growth axis of trees growing in the wet, ambient, and dry treatment sites. A difference in stemwood nutrient levels was observed between the two oak species and among the three treatments. Significant variation in element intensity was observed across treatments for some elements (Ca, K, Mg, Na, N and P) suggesting the potential for long-term impacts on growth under a changing climate regimes for southeastern oaks.

  1. Mountain hemlock growth responds to climatic variability at annual and decadal time scales

    USGS Publications Warehouse

    Peterson, D.W.; Peterson, D.L.

    2001-01-01

    Improved understanding of tree growth responses to climate is needed to model and predict forest ecosystem responses to current and future climatic variability. We used dendroecological methods to study the effects of climatic variability on radial growth of a subalpine conifer, mountain hemlock (Tsuga mertensiana). Tree-ring chronologies were developed for 31 sites, spanning the latitudinal and elevational ranges of mountain hemlock in the Pacific Northwest. Factor analysis was used to identify common patterns of inter-annual growth variability among the chronologies, and correlation and regression analyses were used to identify climatic factors associated with that variability. Factor analysis identified three common growth patterns, representing groups of sites with different climate-growth relationships. At high-elevation and midrange sites in Washington and northern Oregon, growth was negatively correlated with spring snowpack depth, and positively correlated with growth-year summer temperature and the winter Pacific Decadal Oscillation index (PDO). In southern Oregon, growth was negatively correlated with spring snowpack depth and previous summer temperature, and positively correlated with previous summer precipitation. At the low-elevation sites, growth was mostly insensitive to annual climatic variability but displayed sensitivity to decadal variability in the PDO opposite to that found at high-elevation sites. Mountain hemlock growth appears to be limited by late snowmelt, short growing seasons, and cool summer temperatures throughout much of its range in the Pacific Northwest. Earlier snowmelt, higher summer temperatures, and lower summer precipitation in southern Oregon produce conditions under which growth is limited by summer temperature and/or soil water availability. Increasing atmospheric CO2 concentrations could produce warmer temperatures and reduced snowpack depths in the next century. Such changes would likely increase mountain hemlock growth

  2. Rings

    SciTech Connect

    Davis, R.L.

    1989-01-01

    The essence of vortex physics is that at certain low-energy scales elementary excitations of a point particle theory can behave like strings rather than particles. Vortices are the resulting string-like solutions; their thickness sets the distance scale beyond which physics is string-like rather than particle-like. String degrees of freedom are massless in the sense that excitations on a string can have an arbitrarily low frequency. Non-string degrees of freedom correspond to massive particles and are absent from the low energy spectrum. This article considers only field theories with vortices at low energies. The possible existence of a class of solitons in these vortex theories will be discussed. They are vortex rings: they are localized and finite in energy, and able to carry the quantum numbers of point particles. Rings are thus particle-like solutions of a vortex theory, which is itself a limit of a point particle field theory.

  3. Element concentrations in growth rings of trees near an abandoned wood-preserving plant site at Jackson, Tennessee

    USGS Publications Warehouse

    Yanosky, T.M.; Carmichael, J.K.

    1993-01-01

    Multielement analysis was performed on individual annual rings of trees growing at and near an abandoned wood-preserving plant site in Jackson, Tennessee, that operated from the early 1930's until 1981. Numerous organic compounds associated with the wood-preserving process have been detected in soils, ground water, and surface water within much of the site. Tree-ring investigations were conducted prior to investigations of ground water downgradient from the site to determine if trees preserved an areal and temporal record of contaminant movement into offsite areas. Increment cores were collected from trees on the abandoned plant site, in downgradient areas west and south of the site, and at two locations presumably unaffected by contamination from the site. Multielement analysis by proton-induced X-ray emission was performed on 5 to 15 individual growth rings from each of 34 trees that ranged in age from about 5 to 50 years. Concentrations of 16 elements were evaluated by analyzing average concentrations within the 1987, 1989, and 1990 rings of all trees; analyzing element-concentration trends along entire core radii; and analyzing element correlations between and among trees. Concentrations of some nutrients and trace metals were elevated in the outermost sapwood rings of some trees that grow south and southwest of the most contaminated part of the site; small trees on the main part of the site and larger trees to the west generally contained fewer rings with elevated concentrations, particularly of trace metals. Concentrations of several elements elevated in tree rings also were elevated in water samples collected from the reach of a stream that flows near the southwestern part of the site. Multielement analysis of each ring of a willow growing along the southern boundary of the site detected extremely large concentrations of chromium, nickel, and iron in rings that formed in 1986 and thereafter. Relative increases in the concentrations of these elements also

  4. 137Cs distribution among annual rings of different tree species contaminated after the Chernobyl accident.

    PubMed

    Soukhova, N V; Fesenko, S V; Klein, D; Spiridonov, S I; Sanzharova, N I; Badot, P M

    2003-01-01

    The distributions of 137Cs among annual rings of Pinus sylvestris and Betula pendula at four experimental sites located in the most contaminated areas in the Russian territory after the Chernobyl accident in 1986 were studied. Trees of different ages were sampled from four forest sites with different tree compositions and soil properties. The data analysis shows that 137Cs is very mobile in wood and the 1986 rings do not show the highest contamination. The difference between pine and birch in the pattern of radial 137Cs distribution can be satisfactorily explained by the difference in radial ray composition. 137Cs radial distribution in the wood can be described as the sum of two exponential functions for both species. The function parameters are height, age and species dependent. The distribution of 137Cs in birch wood reveals much more pronounced dependence on site characteristics and/or the age of trees than pines. The data obtained can be used to assess 137Cs content in wood. PMID:12683726

  5. Using Novel Approaches in Process-Based Modeling for Interpreting Inter-Annual Variability in Tree Ring Widths, Wood Density Profiles, and Cellulose Isotopic Ratios

    NASA Astrophysics Data System (ADS)

    Friend, A. D.; Babst, F.; Belmecheri, S.; Frank, D. C.; Hacket Pain, A. J.; Hayat, A.; Poulter, B.; Rademacher, T. T.; Trouet, V.

    2015-12-01

    Time series annual of tree ring width, density variation, and oxygen and carbon isotopic compositions have the potential to substantially increase our knowledge of forest responses to environmental variation. However, their interpretation is not straightforward due to the simultaneous influences of a number of confounding factors, including carry-over effects from previous years, variable resource allocation with size, age, and canopy position, species-specific physiologies, and complex interactions between forcings such as temperature, soil moisture, and atmospheric CO2. Here we attempt to tease these factors apart and so substantially improve the interpretability of tree ring archives through the construction and application of novel approaches within a process-based model of individual tree growth. The model incorporates descriptions of xylem cell division, expansion, and secondary wall thickening, apical and lateral meristem activities with internal controls from internal signals, internal carbon storage, and the dynamics of canopy photosynthesis, stomatal movements, evapotranspiration, canopy temperatures, and soil moisture. Alternative treatments of isotopic fractionation and growth controls are evaluated using measured datasets. We demonstrate how this new model approach can be used to assess the information contained in tree rings concerning the influence of increasing atmospheric CO2 over the past century on growth and water use efficiency at a range of sites.

  6. Double hexagonal graphene ring synthesized using a growth-etching method

    NASA Astrophysics Data System (ADS)

    Liu, Jinyang; Xu, Yangyang; Cai, Hongbing; Zuo, Chuandong; Huang, Zhigao; Lin, Limei; Guo, Xiaomin; Chen, Zhendong; Lai, Fachun

    2016-07-01

    Precisely controlling the layer number, stacking order, edge configuration, shape and structure of graphene is extremely challenging but highly desirable in scientific research. In this report, a new concept named the growth-etching method has been explored to synthesize a graphene ring using the chemical vapor deposition process. The graphene ring is a hexagonal structure, which contains a hexagonal exterior edge and a hexagonal hole in the centre region. The most important concept introduced here is that the oxide nanoparticle derived from annealing is found to play a dual role. Firstly, it acts as a nucleation site to grow the hexagonal graphene domain and then it works as a defect for etching to form a hole. The evolution process of the graphene ring with the etching time was carefully studied. In addition, a double hexagonal graphene ring was successfully synthesized for the first time by repeating the growth-etching process, which not only confirms the validity and repeatability of the method developed here but may also be further extended to grow unique graphene nanostructures with three, four, or even tens of graphene rings. Finally, a schematic model was drawn to illustrate how the double hexagonal graphene ring is generated and propagated. The results shown here may provide valuable guidance for the design and growth of unique nanostructures of graphene and other two-dimensional materials.

  7. Double hexagonal graphene ring synthesized using a growth-etching method.

    PubMed

    Liu, Jinyang; Xu, Yangyang; Cai, Hongbing; Zuo, Chuandong; Huang, Zhigao; Lin, Limei; Guo, Xiaomin; Chen, Zhendong; Lai, Fachun

    2016-08-01

    Precisely controlling the layer number, stacking order, edge configuration, shape and structure of graphene is extremely challenging but highly desirable in scientific research. In this report, a new concept named the growth-etching method has been explored to synthesize a graphene ring using the chemical vapor deposition process. The graphene ring is a hexagonal structure, which contains a hexagonal exterior edge and a hexagonal hole in the centre region. The most important concept introduced here is that the oxide nanoparticle derived from annealing is found to play a dual role. Firstly, it acts as a nucleation site to grow the hexagonal graphene domain and then it works as a defect for etching to form a hole. The evolution process of the graphene ring with the etching time was carefully studied. In addition, a double hexagonal graphene ring was successfully synthesized for the first time by repeating the growth-etching process, which not only confirms the validity and repeatability of the method developed here but may also be further extended to grow unique graphene nanostructures with three, four, or even tens of graphene rings. Finally, a schematic model was drawn to illustrate how the double hexagonal graphene ring is generated and propagated. The results shown here may provide valuable guidance for the design and growth of unique nanostructures of graphene and other two-dimensional materials. PMID:27387556

  8. Graphene Layer Growth Chemistry: Five-Six-Ring Flip Reaction

    SciTech Connect

    Whitesides, Russell; Domin, Dominik; Lester Jr., William A.; Frenklach, Michael

    2007-03-24

    A theoretical study revealed a new reaction pathway, in which a fused five and six-membered ring complex on the zigzag edge of a graphene layer isomerizes to reverse its orientation, or 'flips,' after activation by a gaseous hydrogen atom. The process is initiated by hydrogen addition to or abstraction from the surface complex. The elementary steps of the migration pathway were analyzed using density-functional theory (DFT) calculations to examine the region of the potential energy surface associated with the pathway. The DFT calculations were performed on substrates modeled by the zigzag edges of tetracene and pentacene. Rate constants for the flip reaction were obtained by the solution of energy master equation utilizing the DFT energies, frequencies, and geometries. The results indicate that this reaction pathway is competitive with other pathways important to the edge evolution of aromatic species in high temperature environments.

  9. Soil Warming and Fertilization Effects on Growth Ring Widths of Arctic Shrubs - Application of a Novel Dendroecological Approach.

    NASA Astrophysics Data System (ADS)

    Iturrate Garcia, M.; Heijmans, M.; Schweingruber, F. H.; Niklaus, P. A.; Schaepman-Strub, G.

    2015-12-01

    Climate warming is suggested as the main driver of shrub expansion in arctic tundra regions. Shrub expansion may have consequences on biodiversity and climate, especially through its feedbacks with the energy budget. A better understanding of shrub expansion mechanisms, including growth rate patterns and stem anatomy changes, and their sensitivity to climate is needed in order to quantify related feedbacks. We present a novel dendroecological approach to determine the response of three arctic shrub species to increased soil temperature and nutrients. A full factorial block-design experiment was run for four years with a total of thirty plots. Six individuals of each species were sampled from each plot to test for treatment effects on growth rate and stem anatomy. We compared the ring width of the four years of experiment with the one of the four previous years. The preliminary results for Betula nana and Salix pulchra suggest a significant effect of the treatments on the growth ring width. The response is stronger in Salix pulchra than in Betula nana individuals. And, while Salix pulchra is more sensitive to the combined soil warming and fertilization treatment, Betula nana is to the fertilization treatment. We could not observe an effect of treatment on the stem anatomy, likely because bark thickness co-varies with age. We found significant positive correlations of cork, cortex and phloem thickness with xylem thickness (used as a proxy of age), and a significant difference in stem anatomy between species. The results suggest species-specific growth sensitivity to soil warming and nutrient enhancement. The use of experimental dendroecology by manipulating environmental conditions according to future climate scenarios and testing effects on shrub anatomy and annual growth will increase our understanding on shrub expansion mechanisms. Ongoing plant trait analysis and consecutive application in a 3D radiative transfer model will allow to quantify the feedback of

  10. Detecting long-term growth trends using tree rings: a critical evaluation of methods.

    PubMed

    Peters, Richard L; Groenendijk, Peter; Vlam, Mart; Zuidema, Pieter A

    2015-05-01

    Tree-ring analysis is often used to assess long-term trends in tree growth. A variety of growth-trend detection methods (GDMs) exist to disentangle age/size trends in growth from long-term growth changes. However, these detrending methods strongly differ in approach, with possible implications for their output. Here, we critically evaluate the consistency, sensitivity, reliability and accuracy of four most widely used GDMs: conservative detrending (CD) applies mathematical functions to correct for decreasing ring widths with age; basal area correction (BAC) transforms diameter into basal area growth; regional curve standardization (RCS) detrends individual tree-ring series using average age/size trends; and size class isolation (SCI) calculates growth trends within separate size classes. First, we evaluated whether these GDMs produce consistent results applied to an empirical tree-ring data set of Melia azedarach, a tropical tree species from Thailand. Three GDMs yielded similar results - a growth decline over time - but the widely used CD method did not detect any change. Second, we assessed the sensitivity (probability of correct growth-trend detection), reliability (100% minus probability of detecting false trends) and accuracy (whether the strength of imposed trends is correctly detected) of these GDMs, by applying them to simulated growth trajectories with different imposed trends: no trend, strong trends (-6% and +6% change per decade) and weak trends (-2%, +2%). All methods except CD, showed high sensitivity, reliability and accuracy to detect strong imposed trends. However, these were considerably lower in the weak or no-trend scenarios. BAC showed good sensitivity and accuracy, but low reliability, indicating uncertainty of trend detection using this method. Our study reveals that the choice of GDM influences results of growth-trend studies. We recommend applying multiple methods when analysing trends and encourage performing sensitivity and reliability

  11. Mosaic ring chromosome 14 and monosomy 14 presenting with growth retardation, epilepsy, and blepharophimosis.

    PubMed

    Hou, Jia-Woei

    2004-05-01

    Ring chromosomes are rare chromosomal anomalies and usually not stable in nature. Patients carrying ring chromosome have various phenotypes depending on the degree of structural rearrangement. A 1-year-old boy, presenting with hypotonia, blepharophimosis, ptosis, a bulbous nose, mild psychomotor retardation, and epilepsy, was found to have mosaicism of chromosome ring 14 and monosomy 14. His karyotype is described as hitherto unreported mos 46, XY, r(14)(p11.2q32.31 or q32.2)[84]/45, XY,-14[10]/46, XY, dic r(14)[6]. His seizures responded well to phenobarbital. He has marked growth retardation but less serious delays in mental and motor development than those with ring 14 described in the literature. PMID:15366814

  12. Capturing spiral radial growth of conifers using the superellipse to model tree-ring geometric shape

    PubMed Central

    Shi, Pei-Jian; Huang, Jian-Guo; Hui, Cang; Grissino-Mayer, Henri D.; Tardif, Jacques C.; Zhai, Li-Hong; Wang, Fu-Sheng; Li, Bai-Lian

    2015-01-01

    Tree-rings are often assumed to approximate a circular shape when estimating forest productivity and carbon dynamics. However, tree rings are rarely, if ever, circular, thereby possibly resulting in under- or over-estimation in forest productivity and carbon sequestration. Given the crucial role played by tree ring data in assessing forest productivity and carbon storage within a context of global change, it is particularly important that mathematical models adequately render cross-sectional area increment derived from tree rings. We modeled the geometric shape of tree rings using the superellipse equation and checked its validation based on the theoretical simulation and six actual cross sections collected from three conifers. We found that the superellipse better describes the geometric shape of tree rings than the circle commonly used. We showed that a spiral growth trend exists on the radial section over time, which might be closely related to spiral grain along the longitudinal axis. The superellipse generally had higher accuracy than the circle in predicting the basal area increment, resulting in an improved estimate for the basal area. The superellipse may allow better assessing forest productivity and carbon storage in terrestrial forest ecosystems. PMID:26528316

  13. Integrating inter- and intra-annual tree-ring width, carbon isotopes and anatomy: responses to climate variability in a temperate oak forest

    NASA Astrophysics Data System (ADS)

    Granda, Elena; Bazot, Stéphane; Fresneau, Chantal; Boura, Anaïs; Faccioni, Georgia; Damesin, Claire

    2015-04-01

    While many forests are experiencing strong tree declines due to climate change in temperate ecosystems, others nearby to those declining show no apparent signs of decline. This could be due to particular microsite conditions or, for instance, to a higher plasticity of given traits that allow a better performance under stressful conditions. We studied oak functional mechanisms (Quercus petraea) leading to the apparently healthy status of the forest and their relation to the observed climatic variability. This study was conducted in the Barbeau Forest (northern France), where cores from mature trees were collected. Three types of functional traits (secondary growth, physiological variables - δ13C and derived Δ13C and iWUE- and several anatomical ones -e.g. vessel area, density-) were recorded for each ring for the 1991-2011 period, distinguishing EW from LW in all measured traits. Among the three types of functional traits, those related to growth experienced the highest variability both between years and between individuals, followed by anatomical and physiological ones. Secondary growth maintained a constant trend during the study period. Instead, ring, EW and LW δ13C slightly declined from 1991 to 2011. Additional intra-ring δ13C analyses allowed for a more detailed understanding of the seasonal dynamics within each year. In particular, the year 2007 (an especially favorable climatic year during the growing season) showed the lowest δ13C values during the EW-LW transition for the whole study period. Inter-annual anatomical traits varied in their responses, but in general, no temporal trends were found. The results from structural equation modeling (SEM) showed direct relationships of seasonal climate and growth, as well as indirect relationships mediated by anatomical and physiological traits. We further discuss the implications of these results on future forest responses to ongoing climate changes.

  14. Inequality of Size and Size Increment in Pinus banksiana in Relation to Stand Dynamics and Annual Growth Rate

    PubMed Central

    Metsaranta, Juha M.; Lieffers, Victor J.

    2008-01-01

    Background and Aims Changes in size inequality in tree populations are often attributed to changes in the mode of competition over time. The mode of competition may also fluctuate annually in response to variation in growing conditions. Factors causing growth rate to vary can also influence competition processes, and thus influence how size hierarchies develop. Methods Detailed data obtained by tree-ring reconstruction were used to study annual changes in size and size increment inequality in several even-aged, fire-origin jack pine (Pinus banksiana) stands in the boreal shield and boreal plains ecozones in Saskatchewan and Manitoba, Canada, by using the Gini and Lorenz asymmetry coefficients. Key Results The inequality of size was related to variables reflecting long-term stand dynamics (e.g. stand density, mean tree size and average competition, as quantified using a distance-weighted absolute size index). The inequality of size increment was greater and more variable than the inequality of size. Inequality of size increment was significantly related to annual growth rate at the stand level, and was higher when growth rate was low. Inequality of size increment was usually due primarily to large numbers of trees with low growth rates, except during years with low growth rate when it was often due to small numbers of trees with high growth rates. The amount of competition to which individual trees were subject was not strongly related to the inequality of size increment. Conclusions Differences in growth rate among trees during years of poor growth may form the basis for development of size hierarchies on which asymmetric competition can act. A complete understanding of the dynamics of these forests requires further evaluation of the way in which factors that influence variation in annual growth rate also affect the mode of competition and the development of size hierarchies. PMID:18089583

  15. Growth patterns and age validation from otolith ring deposition in New Zealand longfin eels Anguilla dieffenbachii recaptured after 10 years at large.

    PubMed

    Beentjes, M P; Jellyman, D J

    2015-03-01

    In 1998, 9500 juvenile New Zealand longfin eels Anguilla dieffenbachii (mean total length, LT , 42 cm) captured from the lower Clutha River were transferred upstream to Lake Hawea, a high-country oligotrophic lake in the same catchment where recruitment of juvenile eels has been prevented by hydroelectric dams since 1958. A total of 2010 of the transferred A. dieffenbachii were tagged with coded wire tags. Ten years later in 2008, the A. dieffenbachii population in Lake Hawea was sampled resulting in 399 recaptures (distinguishable by the presence of tags and by LT from the remnant resident population of large old A. dieffenbachii) of the 1998 transfers; 79 (19·2%) of the recaptured fish had tags compared with 21·3% at release, indicating good tag retention and low mortality due to tagging. All recaptured tagged A. dieffenbachii were female. Mean annual growth over the 10 years since release was 3·80 cm year(-1) for all recaptures and 3·65 cm year(-1) for tag recaptures, and both were significantly greater than the estimate of 2·38 cm year(-1) at release. After release, mean condition (K) increased significantly (P < 0·001) for all recaptures and tag recaptures. Annual length growth increment was linear. Tag recaptures showed significant increases in somatic growth rate post-transfer, and otoliths from the 2008 recaptured A. dieffenbachii were examined to see whether any similar enhanced growth after transfer was incorporated into the otolith structure that would serve as a date stamp. Measurement of otolith ring radii indicated that an increase in the radius occurred on most otoliths corresponding to the year after transfer. Because there was 9 years of completed growth following the observed growth inflection on the otoliths, this was strong evidence that opaque rings were formed annually. PMID:25644125

  16. National health expenditure projections: modest annual growth until coverage expands and economic growth accelerates.

    PubMed

    Keehan, Sean P; Cuckler, Gigi A; Sisko, Andrea M; Madison, Andrew J; Smith, Sheila D; Lizonitz, Joseph M; Poisal, John A; Wolfe, Christian J

    2012-07-01

    For 2011-13, US health spending is projected to grow at 4.0 percent, on average--slightly above the historically low growth rate of 3.8 percent in 2009. Preliminary data suggest that growth in consumers' use of health services remained slow in 2011, and this pattern is expected to continue this year and next. In 2014, health spending growth is expected to accelerate to 7.4 percent as the major coverage expansions from the Affordable Care Act begin. For 2011 through 2021, national health spending is projected to grow at an average rate of 5.7 percent annually, which would be 0.9 percentage point faster than the expected annual increase in the gross domestic product during this period. By 2021, federal, state, and local government health care spending is projected to be nearly 50 percent of national health expenditures, up from 46 percent in 2011, with federal spending accounting for about two-thirds of the total government share. Rising government spending on health care is expected to be driven by faster growth in Medicare enrollment, expanded Medicaid coverage, and the introduction of premium and cost-sharing subsidies for health insurance exchange plans. PMID:22692089

  17. Validating Annual Growth Bands of Deep Sea Corals from the Gulf of Mexico and Southeastern United States

    NASA Astrophysics Data System (ADS)

    Mohon, L. M.; Roark, E.; Guillemette, R. N.; Prouty, N.; Ross, S.

    2012-12-01

    The deep-water black corals, Leiopathes sp., have the potential to be used as an archive of historical oceanographic and biochemical changes. Deep-sea corals can extend our observations of ocean dynamics and climate well beyond the onset of instrumental records. In this study we investigate different methods of determining the growth rates and age distributions of deep-water black corals (Leiopathes sp.) in the Gulf of Mexico and the southeastern Unites States. Leiopathes sp. grow in a tree-like fashion by depositing growth rings resulting in decadally resolved and perhaps annually resolved paleoceanographic records. We use radiocarbon measurements to validate annual growth bands and annual variations in iodine concentrations. Radiocarbon results from five specimens show that these animals have been growing continuously for at least the last two millennia, with growth rates ranging from 8 to 22 μm yr-1. Results from scanning electron microscope (SEM) work to image growth rings (90x and 900x) in back-scattered electrons (BSE) mode and measure iodine by wavelength dispersive spectrometer (WDS). Ages were determined by the counting of growth bands by independent observes and counting of peaks of iodine and BSE measured with 1 μm spots shoulder to shoulder across the radius of the specimen. Peaks in iodine concentration associated with the glueing regions of the growth bands are also in excellent agreement with the radiocarbon results suggesting annual ring formation. For example in one specimen from the Gulf of Mexico (GOM-JSL04-4734-BC1), the 14C derived age (670 ± 40 yrs.) was in excellent agreement with the iodine derived age of (666 ± 65 yrs.), while the BSE counts (626 ± 60 yrs.) and the visual ring counts (783 ±78 yrs.) were only in good agreement. These results indicate that at a minimum, the iodine derived ages can be used as an independent chronology. Iodine derived ages were used to determine the atmospheric 14C age which was subtracted from the

  18. Annual precipitation in Liancheng, China, since 1777 AD derived from tree rings of Chinese pine ( Pinus tabulaeformis Carr.)

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Lei, Ying; Sun, Bo; Song, Huiming; Sun, Junyan

    2013-11-01

    Precipitation from the previous August to the current June over the last 232 years in Liancheng, China, was reconstructed by a transfer function based on the correlation between tree-ring widths and local meteorological data. The explained variance was 45.3 %, and fluctuations on both annual and decadal scales were captured. Wet periods with precipitation above the 232-year mean occurred from 1777 to 1785, 1802 to 1818, 1844 to 1861, 1889 to 1922 and 1939 to 1960. Dry periods (precipitation below the mean) occurred from 1786 to 1801, 1819 to 1843, 1862 to 1888 and 1923 to 1938. The reconstruction compares well with a tree-ring-based precipitation reconstruction at Mt. Xinglong; both of them showed the well-known severe drought in the late 1920s. The rainfall series also shows highly synchronous decreasing trends since the 1940s, suggesting that precipitation related to the East Asian summer monsoon at these two sites has decreased by large spatial and temporal (decadal) scales. Power spectrum analysis of the reconstruction showed remarkable 21.82-, 3.48-, 3.12-, 3.08- and 2.31-year cycles for the past 232 years; the 22-year cycle corresponds to the solar cycle and is expressed widely in tree ring/precipitation reconstructions on the China Loess Plateau. This may suggest a solar influence on the precipitation variations on the Loess Plateau, although the mechanisms are not well understood.

  19. Age trends in tree ring growth and isotopic archives: A case study of Pinus sylvestris L. from northwestern Norway

    NASA Astrophysics Data System (ADS)

    Young, Giles H. F.; Demmler, Joanne C.; Gunnarson, BjöRn E.; Kirchhefer, Andreas J.; Loader, Neil J.; McCarroll, Danny

    2011-06-01

    Measurements of tree ring width and relative density have contributed significantly to many of the large-scale reconstructions of past climatic change, but to extract the climate signal it is first necessary to remove any nonclimatic age-related trends. This detrending can limit the lower-frequency climate information that may be extracted from the archive (the "segment length curse"). This paper uses a data set of ring widths, maximum latewood density and stable carbon and oxygen isotopes from 28 annually resolved series of known-age Pinus sylvestris L. trees in northwestern Norway to test whether stable isotopes in tree rings require an equivalent statistical detrending. Results indicate that stable oxygen and carbon isotope ratios from tree rings whose cambial age exceeds c.50 years exhibit no significant age trends and thus may be used to reconstruct environmental variability and physiological processes at this site without the potential loss of low-frequency information associated with detrending.

  20. Growth rate and ring width variability of teak, Tectona grandis (Verbenaceae) in an unmanaged forest in East Timor.

    PubMed

    Sousa, Vicelina B; Cardoso, Sofia; Quilhó, Teresa; Pereira, Helena

    2012-03-01

    Teak (Tectona grandis) is one of the most valuable timbers in international trade and an important species for tropical forestry. Teak is found on the island of East Timor but no information is available on teak growth from this region. A pure stand planted in 1940-50 in the North of East Timor and left unmanaged was studied. Fifteen trees were sampled in October-November 2003 and stem discs taken at three height levels of its height (1.7m, 9.5m and 18.7m), and cores were collected at DBH. Transverse surfaces of the discs and cores were polished for ring identification. Core cross sections were first digitized and disc cross sections were observed under the microscope. Three randomly selected radii were analyzed in each disc. Ring width measurement and ring counting were done using image analysis software. The distinction between heartwood and sapwood was performed macroscopically by colour difference, and heartwood radius and sapwood width were measured. The relationship between stem and heartwood radius was studied for each disc and heartwood percentage by radius was determined. Radial ring width curves are presented for the different axial positions within the stem, and ring width variability was analyzed. Growth rates were calculated and age-radius relationships were estimated using cumulative growth curves. Growth rings were large and well defined in the juvenile phase, reflecting the specie's fast-growing character. The year-to-year variation of ring width showed a similar pattern among trees. Mean ring width ranged between 4.3-7.3mm for the first 20 years and 3.3-5.1mm for 30 to 45 years. Pith eccentricity was evident in the lower part of the stem and ring wedging occurred. On average, heartwood represented 84% of the radius and sapwood contained 6 to 11 rings. The age-related variation of ring width and the occurrence in the lower part of the tree stems of eccentricity and wedging rings, highlights the importance of appropriate stand management

  1. Responses of tree-ring growth and crop yield to drought indices in the Shanxi province, North China.

    PubMed

    Sun, Junyan; Liu, Yu

    2014-09-01

    In this paper, we analyze the relationships among the tree-ring chronology, meteorological drought (precipitation), agricultural drought (Palmer Drought Severity Index PDSI), hydrological drought (runoff), and agricultural data in the Shanxi province of North China. Correlation analyses indicate that the tree-ring chronology is significantly correlated with all of the drought indices during the main growing season from March to July. Sign test analyses further indicate that the tree-ring chronology shows variation similar to that of the drought indices in both high and low frequencies. Comparisons of the years with narrow tree rings to the severe droughts reflected in all three indices from 1957 to 2008 reveal that the radial growth of the trees in the study region can accurately record the severe drought for which all three indices were in agreement (1972, 1999, 2000, and 2001). Comparisons with the dryness/wetness index indicate that tree-ring growth can properly record the severe droughts in the history. Correlation analyses among agricultural data, tree-ring chronology, and drought indices indicate that the per-unit yield of summer crops is relatively well correlated with the agricultural drought, as indicated by the PDSI. The PDSI is the climatic factor that significantly influences both tree growth and per-unit yield of summer crops in the study region. These results indicate that the PDSI and tree-ring chronology have the potential to be used to monitor and predict the yield of summer crops. Tree-ring chronology is an important tool for drought research and for wider applications in agricultural and hydrological research. PMID:24162181

  2. Btk29A-mediated tyrosine phosphorylation of armadillo/β-catenin promotes ring canal growth in Drosophila oogenesis.

    PubMed

    Hamada-Kawaguchi, Noriko; Nishida, Yasuyoshi; Yamamoto, Daisuke

    2015-01-01

    Drosophila Btk29A is the ortholog of mammalian Btk, a Tec family nonreceptor tyrosine kinase whose deficit causes X-linked agammaglobulinemia in humans. The Btk29AficP mutation induces multiple abnormalities in oogenesis, including the growth arrest of ring canals, large intercellular bridges that allow the flow of cytoplasm carrying maternal products essential for embryonic development from the nurse cells to the oocyte during oogenesis. In this study, inactivation of Parcas, a negative regulator of Btk29A, was found to promote Btk29A accumulation on ring canals with a concomitant increase in the ring canal diameter, counteracting the Btk29AficP mutation. This mutation markedly reduced the accumulation of phosphotyrosine on ring canals and in the regions of cell-cell contact, where adhesion-supporting proteins such as DE-cadherin and β-catenin ortholog Armadillo (Arm) are located. Our previous in vitro and in vivo analyses revealed that Btk29A directly phosphorylates Arm, leading to its release from DE-cadherin. In the present experiments, immunohistological analysis revealed that phosphorylation at tyrosine 150 (Y150) and Y667 of Arm was diminished in Btk29AficP mutant ring canals. Overexpression of an Arm mutant with unphosphorylatable Y150 inhibited ring canal growth. Thus Btk29A-induced Y150 phosphorylation is necessary for the normal growth of ring canals. We suggest that the dissociation of tyrosine-phosphorylated Arm from DE-cadherin allows dynamic actin to reorganize, leading to ring canal expansion and cell shape changes during the course of oogenesis. PMID:25803041

  3. Understanding tree growth in response to moisture variability: Linking 32 years of satellite based soil moisture observations with tree rings

    NASA Astrophysics Data System (ADS)

    Albrecht, Franziska; Dorigo, Wouter; Gruber, Alexander; Wagner, Wolfgang; Kainz, Wolfgang

    2014-05-01

    Climate change induced drought variability impacts global forest ecosystems and forest carbon cycle dynamics. Physiological drought stress might even become an issue in regions generally not considered water-limited. The water balance at the soil surface is essential for forest growth. Soil moisture is a key driver linking precipitation and tree development. Tree ring based analyses are a potential approach to study the driving role of hydrological parameters for tree growth. However, at present two major research gaps are apparent: i) soil moisture records are hardly considered and ii) only a few studies are linking tree ring chronologies and satellite observations. Here we used tree ring chronologies obtained from the International Tree ring Data Bank (ITRDB) and remotely sensed soil moisture observations (ECV_SM) to analyze the moisture-tree growth relationship. The ECV_SM dataset, which is being distributed through ESA's Climate Change Initiative for soil moisture covers the period 1979 to 2010 at a spatial resolution of 0.25°. First analyses were performed for Mongolia, a country characterized by a continental arid climate. We extracted 13 tree ring chronologies suitable for our analysis from the ITRDB. Using monthly satellite based soil moisture observations we confirmed previous studies on the seasonality of soil moisture in Mongolia. Further, we investigated the relationship between tree growth (as reflected by tree ring width index) and remotely sensed soil moisture records by applying correlation analysis. In terms of correlation coefficient a strong response of tree growth to soil moisture conditions of current April to August was observed, confirming a strong linkage between tree growth and soil water storage. The highest correlation was found for current April (R=0.44), indicating that sufficient water supply is vital for trees at the beginning of the growing season. To verify these results, we related the chronologies to reanalysis precipitation and

  4. Reconstruction of Pacific salmon abundance from riparian tree-ring growth.

    PubMed

    Drake, D C; Naiman, Robert J

    2007-07-01

    We use relationships between modern Pacific salmon (Oncorhynchus spp.) escapement (migrating adults counted at weirs or dams) and riparian tree-ring growth to reconstruct the abundance of stream-spawning salmon over 150-350 years. After examining nine sites, we produced reconstructions for five mid-order rivers and four salmon species over a large geographic range in the Pacific Northwest: chinook (O. tschwatcha) in the Umpqua River, Oregon, USA; sockeye (O. nerka) in Drinkwater Creek, British Columbia, Canada; pink (O. gorbuscha) in Sashin Creek, southeastern Alaska, USA; chum (O. keta) in Disappearance Creek, southeastern Alaska, USA; and pink and chum in the Kadashan River, southeastern Alaska, USA. We first derived stand-level, non-climatic growth chronologies from riparian trees using standard dendroecology methods and differencing. When the chronologies were compared to 18-55 years of adult salmon escapement we detected positive, significant correlations at five of the nine sites. Regression models relating escapement to tree-ring growth at the five sites were applied to the differenced chronologies to reconstruct salmon abundance. Each reconstruction contains unique patterns characteristic of the site and salmon species. Reconstructions were validated by comparison to local histories (e.g., construction of dams and salmon canneries) and regional fisheries data such as salmon landings and aerial surveys and the Pacific Decadal Oscillation climate index. The reconstructions capture lower-frequency cycles better than extremes and are most useful for determination and comparison of relative abundance, cycles, and the effects of interventions. Reconstructions show lower population cycle maxima in both Umpqua River chinook and Sashin Creek pink salmon in recent decades. The Drinkwater Creek reconstruction suggests that sockeye abundance since the mid-1990s has been 15-25% higher than at any time since 1850, while no long-term deviations from natural cycles are

  5. Fish otoliths: daily growth layers and periodical patterns.

    PubMed

    Panella, G

    1971-09-17

    The early-stage annual rings in otoliths from some cold-temperate fish consist of thin growth bands, the number of which corresponds to that of the days in a year. This indicates that growth takes place by daily increments. Other recurrent patterns show a fortnightly and monthly periodicity. Spawning rings are microscopically distinguishable from winter rings. PMID:5098955

  6. Regime switch in karstic caves atmosphere; possible consequence on annual speleothem growth.

    NASA Astrophysics Data System (ADS)

    Bourges, F.; Genthon, P.; Mangin, A.; D'Hulst, D.

    2005-12-01

    Speleothem are usually considered as records of past climate, and are supposed to present annual growth rings. Yet, they grow inside caves that benefit from very stable environment. However, Bourges et al. 2001, have shown that the atmosphere of Aven d'Orgnac (South East France), was characterized by drop of CO2 concentration and 222Rn activity at the end of autumn and presented each year the succession of a winter and a summer regime. Temperature data are now used to constrain the climate of this cave system. Our data consist in 5 years monitoring with 0.01°C accuracy, three short thermal profiling campaigns, and sparser data gathered in different French painted caves. Near the opening of Aven d'Orgnac, the Salle de Jolys room records each year at the end of autumn the onset of the winter regime that is shown to be triggered by the inverse density stratification induced by the decrease of the outside night temperature. Comparison of summer and winter vertical temperature profiles point to a thermoconvective destabilization of this room atmosphere, involving the downward flow of cold outside bearing air near the cave floor during winter nights. The winter regime propagates then stepwise inside the Aven d'Orgnac cave system. In Salle Plane, which is situated more than one kilometer away from the entrance, the winter regime has never been observed. Our thermal profiling experiment shows there low amplitude (0.03°C) temperature changes, with major daily and half daily components, that are strongly correlated with the pressure first time derivative. Comparison with temperature records from other rooms of the Aven d'Orgnac cave system and with other caves monitored by our team suggest that a strong correlation between temperature changes and the pressure first time derivative could be considered as a clue to the confined character of a given cave room. We propose therefore that the Aven d'Orgnac cave system could be divided in two parts : the open system, where the

  7. Radiocarbon in annual coral rings from the eastern tropical Pacific ocean

    SciTech Connect

    Druffel, E.M.

    1981-01-01

    Sixty radiocarbon measurements were performed on aragonite from annually banded corals collected from three sites in the Galapagos Islands. Preanthropogenic ..delta../sup 14/C values of coral that grew around A.D. 1930 averaged -70%/sub 0/. This is substantially lower than average values previously reported (-51%/sub 0/) for corals from Florida and Belize in the western North Atlantic Ocean. A decrease of 6% was noticed in coral that grew from 1930 to 1954. This decrease could be interpreted as a Suess effect in surface ocean water. The 100%/sub 0/ increase in ..delta../sup 14/C for coral that grew from 1954 to 1973 is the result of bomb-produced /sup 14/C that was introduced to the surface ocean waters. The /sup 14/C levels in corals that grew during El Nino years were considerably higher than those for normal years. These higher values are attributed to the absence of upwelling at the equator during El Nino events.

  8. An Annual Plant Growth Proxy in the Mojave Desert Using MODIS-EVI Data

    PubMed Central

    Wallace, Cynthia S.A.; Thomas, Kathryn A.

    2008-01-01

    In the arid Mojave Desert, the phenological response of vegetation is largely dependent upon the timing and amount of rainfall, and maps of annual plant cover at any one point in time can vary widely. Our study developed relative annual plant growth models as proxies for annual plant cover using metrics that captured phenological variability in Moderate-Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) satellite images. We used landscape phenologies revealed in MODIS data together with ecological knowledge of annual plant seasonality to develop a suite of metrics to describe annual growth on a yearly basis. Each of these metrics was applied to temporally-composited MODIS-EVI images to develop a relative model of annual growth. Each model was evaluated by testing how well it predicted field estimates of annual cover collected during 2003 and 2005 at the Mojave National Preserve. The best performing metric was the spring difference metric, which compared the average of three spring MODIS-EVI composites of a given year to that of 2002, a year of record drought. The spring difference metric showed correlations with annual plant cover of R2 = 0.61 for 2005 and R2 = 0.47 for 2003. Although the correlation is moderate, we consider it supportive given the characteristics of the field data, which were collected for a different study in a localized area and are not ideal for calibration to MODIS pixels. A proxy for annual growth potential was developed from the spring difference metric of 2005 for use as an environmental data layer in desert tortoise habitat modeling. The application of the spring difference metric to other imagery years presents potential for other applications such as fuels, invasive species, and dust-emission monitoring in the Mojave Desert.

  9. An annual plant growth proxy in the Mojave Desert using MODIS-EVI data

    USGS Publications Warehouse

    Wallace, C.S.A.; Thomas, K.A.

    2008-01-01

    In the arid Mojave Desert, the phenological response of vegetation is largely dependent upon the timing and amount of rainfall, and maps of annual plant cover at any one point in time can vary widely. Our study developed relative annual plant growth models as proxies for annual plant cover using metrics that captured phenological variability in Moderate-Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) satellite images. We used landscape phenologies revealed in MODIS data together with ecological knowledge of annual plant seasonality to develop a suite of metrics to describe annual growth on a yearly basis. Each of these metrics was applied to temporally-composited MODIS-EVI images to develop a relative model of annual growth. Each model was evaluated by testing how well it predicted field estimates of annual cover collected during 2003 and 2005 at the Mojave National Preserve. The best performing metric was the spring difference metric, which compared the average of three spring MODIS-EVI composites of a given year to that of 2002, a year of record drought. The spring difference metric showed correlations with annual plant cover of R2 = 0.61 for 2005 and R 2 = 0.47 for 2003. Although the correlation is moderate, we consider it supportive given the characteristics of the field data, which were collected for a different study in a localized area and are not ideal for calibration to MODIS pixels. A proxy for annual growth potential was developed from the spring difference metric of 2005 for use as an environmental data layer in desert tortoise habitat modeling. The application of the spring difference metric to other imagery years presents potential for other applications such as fuels, invasive species, and dust-emission monitoring in the Mojave Desert.

  10. Seasonal variations in the stable oxygen isotope ratio of wood cellulose reveal annual rings of trees in a Central Amazon terra firme forest.

    PubMed

    Ohashi, Shinta; Durgante, Flávia M; Kagawa, Akira; Kajimoto, Takuya; Trumbore, Susan E; Xu, Xiaomei; Ishizuka, Moriyoshi; Higuchi, Niro

    2016-03-01

    In Amazonian non-flooded forests with a moderate dry season, many trees do not form anatomically definite annual rings. Alternative indicators of annual rings, such as the oxygen (δ(18)Owc) and carbon stable isotope ratios of wood cellulose (δ(13)Cwc), have been proposed; however, their applicability in Amazonian forests remains unclear. We examined seasonal variations in the δ(18)Owc and δ(13)Cwc of three common species (Eschweilera coriacea, Iryanthera coriacea, and Protium hebetatum) in Manaus, Brazil (Central Amazon). E. coriacea was also sampled in two other regions to determine the synchronicity of the isotopic signals among different regions. The annual cyclicity of δ(18)Owc variation was cross-checked by (14)C dating. The δ(18)Owc showed distinct seasonal variations that matched the amplitude observed in the δ(18)O of precipitation, whereas seasonal δ(13)Cwc variations were less distinct in most cases. The δ(18)Owc variation patterns were similar within and between some individual trees in Manaus. However, the δ(18)Owc patterns of E. coriacea differed by region. The ages of some samples estimated from the δ(18)Owc cycles were offset from the ages estimated by (14)C dating. In the case of E. coriacea, this phenomenon suggested that missing or wedging rings may occur frequently even in well-grown individuals. Successful cross-dating may be facilitated by establishing δ(18)Owc master chronologies at both seasonal and inter-annual scales for tree species with distinct annual rings in each region. PMID:26621690

  11. Development of a rainfall sensitive tree-ring chronology in Zimbabwe

    SciTech Connect

    Stahle, D.W.; Cleaveland, M.K.; Nicholson, S.E.

    1997-11-01

    This paper reports the discovery of annual tree ring formation in two species of trees in Zimbabwe and describes their paleoclimatic reconstruction potential. Due to the strong influence of El Nino-Southern Oscillation on the climate and crop yields of Zimbabwe and surrenting areas, and the rarity of annual tree ring chronologies in the tropics, the discovery of climatically sensitive growth rings is extremely significant. In particular, the Pterocarpus angolensis shows a strong correlation between the derived tree ring chronology and regional rainfall amounts. Based on sampling at the Sikumi Forest, it is speculated that P. angolensis may routinely achieve over 200 years in age. Four lines of evidence are identified which indicate that the semi-ring porous growth bands in P. angolensis are exactly annual growth rings. 18 refs., 3 figs.

  12. Growth Regulator Herbicides Prevent Invasive Annual Grass Seed Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Auxinic herbicides, such as 2,4-D and dicamba, that act as plant growth regulators are commonly used for broadleaf weed control in cereal crops (e.g. wheat, barley), grasslands, and non-croplands. If applied at later growth stages, while cereals are developing reproductive parts, the herbicides can...

  13. A general model of intra-annual tree growth using dendrometer bands.

    PubMed

    McMahon, Sean M; Parker, Geoffrey G

    2015-01-01

    Tree growth is an important indicator of forest health, productivity, and demography. Knowing precisely how trees' grow within a year, instead of across years, can lead to a finer understanding of the mechanisms that drive these larger patterns. The growing use of dendrometer bands in research forests has only rarely been used to measure growth at resolutions finer than yearly, but intra-annual growth patterns can be observed from dendrometer bands using precision digital calipers and weekly measurements. Here we present a workflow to help forest ecologists fit growth models to intra-annual measurements using standard optimization functions provided by the R platform. We explain our protocol, test uncertainty in parameter estimates with respect to sample sizes, extend the optimization protocol to estimate robust lower and upper annual diameter bounds, and discuss potential challenges to optimal fits. We offer R code to implement this workflow. We found that starting values and initial optimization routines are critical to fitting the best functional forms. After using a bounded, broad search method, a more focused search algorithm obtained consistent results. To estimate starting and ending annual diameters, we combined the growth function with early and late estimates of beginning and ending growth. Once we fit the functions, we present extension algorithms that estimate periodic reductions in growth, total growth, and present a method of controlling for the shifting allocation to girth during the growth season. We demonstrate that with these extensions, an analysis of growth response to weather (e.g., the water available to a tree) can be derived in a way that is comparable across trees, years, and sites. Thus, this approach, when applied across broader data sets, offers a pathway to build inference about the effects of seasonal weather on growth, size- and light-dependent patterns of growth, species-specific patterns, and phenology. PMID:25691954

  14. A general model of intra-annual tree growth using dendrometer bands

    PubMed Central

    McMahon, Sean M; Parker, Geoffrey G

    2015-01-01

    Tree growth is an important indicator of forest health, productivity, and demography. Knowing precisely how trees' grow within a year, instead of across years, can lead to a finer understanding of the mechanisms that drive these larger patterns. The growing use of dendrometer bands in research forests has only rarely been used to measure growth at resolutions finer than yearly, but intra-annual growth patterns can be observed from dendrometer bands using precision digital calipers and weekly measurements. Here we present a workflow to help forest ecologists fit growth models to intra-annual measurements using standard optimization functions provided by the R platform. We explain our protocol, test uncertainty in parameter estimates with respect to sample sizes, extend the optimization protocol to estimate robust lower and upper annual diameter bounds, and discuss potential challenges to optimal fits. We offer R code to implement this workflow. We found that starting values and initial optimization routines are critical to fitting the best functional forms. After using a bounded, broad search method, a more focused search algorithm obtained consistent results. To estimate starting and ending annual diameters, we combined the growth function with early and late estimates of beginning and ending growth. Once we fit the functions, we present extension algorithms that estimate periodic reductions in growth, total growth, and present a method of controlling for the shifting allocation to girth during the growth season. We demonstrate that with these extensions, an analysis of growth response to weather (e.g., the water available to a tree) can be derived in a way that is comparable across trees, years, and sites. Thus, this approach, when applied across broader data sets, offers a pathway to build inference about the effects of seasonal weather on growth, size- and light-dependent patterns of growth, species-specific patterns, and phenology. PMID:25691954

  15. Variations in Environmental Signals in Tree-Ring Indices in Trees with Different Growth Potential.

    PubMed

    Hafner, Polona; Gričar, Jožica; Skudnik, Mitja; Levanič, Tom

    2015-01-01

    We analysed two groups of Quercus robur trees, growing at nearby plots with different micro-location condition (W-wet and D-dry) in the floodplain Krakovo forest, Slovenia. In the study we compared the growth response of two different tree groups to environmental variables, the potential signal stored in earlywood (EW) structure and the potential difference of the information stored in carbon isotope discrimination of EW and latewood (LW). For that purpose EW and LW widths and carbon isotope discrimination for the period 1970-2008 AD were measured. EW and LW widths were measured on stained microscopic slides and chronologies were standardised using the ARSTAN program. α-cellulose was extracted from pooled EW and LW samples and homogenized samples were further analysed using an elemental analyser and IRMS. We discovered that W oaks grew significantly better over the whole analysed period. The difference between D and W oaks was significant in all analysed variables with the exception of stable carbon isotope discrimination in latewood. In W oaks, latewood widths correlated with summer (June to August) climatic variables, while carbon isotope discrimination was more connected to River Krka flow during the summer. EW discrimination correlated with summer and autumn River Krka flow of the previous year, while latewood discrimination correlated with flow during the current year. In the case of D oaks, the environmental signal appears to be vague, probably due to less favourable growth conditions resulting in markedly reduced increments. Our study revealed important differences in responses to environmental factors between the two oak groups of different physiological conditions that are preconditioned by environmental stress. Environmental information stored in tree-ring features may vary, even within the same forest stand, and largely depends on the micro-environment. Our analysis confirmed our assumptions that separate EW and LW analysis of widths and carbon isotope

  16. Variations in Environmental Signals in Tree-Ring Indices in Trees with Different Growth Potential

    PubMed Central

    Hafner, Polona; Gričar, Jožica; Skudnik, Mitja; Levanič, Tom

    2015-01-01

    We analysed two groups of Quercus robur trees, growing at nearby plots with different micro-location condition (W-wet and D-dry) in the floodplain Krakovo forest, Slovenia. In the study we compared the growth response of two different tree groups to environmental variables, the potential signal stored in earlywood (EW) structure and the potential difference of the information stored in carbon isotope discrimination of EW and latewood (LW). For that purpose EW and LW widths and carbon isotope discrimination for the period 1970–2008 AD were measured. EW and LW widths were measured on stained microscopic slides and chronologies were standardised using the ARSTAN program. α-cellulose was extracted from pooled EW and LW samples and homogenized samples were further analysed using an elemental analyser and IRMS. We discovered that W oaks grew significantly better over the whole analysed period. The difference between D and W oaks was significant in all analysed variables with the exception of stable carbon isotope discrimination in latewood. In W oaks, latewood widths correlated with summer (June to August) climatic variables, while carbon isotope discrimination was more connected to River Krka flow during the summer. EW discrimination correlated with summer and autumn River Krka flow of the previous year, while latewood discrimination correlated with flow during the current year. In the case of D oaks, the environmental signal appears to be vague, probably due to less favourable growth conditions resulting in markedly reduced increments. Our study revealed important differences in responses to environmental factors between the two oak groups of different physiological conditions that are preconditioned by environmental stress. Environmental information stored in tree-ring features may vary, even within the same forest stand, and largely depends on the micro-environment. Our analysis confirmed our assumptions that separate EW and LW analysis of widths and carbon

  17. 2004 ACAA survey reflects continued annual growth in ash utilization

    SciTech Connect

    2006-07-01

    The American Coal Ash Association's 38th Annual Coal Combustion Products (CCP) Production and Use Survey results were released in September for data year 2004. Beneficial CCP utilization tonnage went up by a noteworthy 4.5% from 2003 figures, while production showed very little change at only 0.6%. The estimated total coal ash used versus CCPs produced in 2004 was 40.1% an increase from 2003's 38.1%. The article summarises results of the survey. 1 tab., 5 charts.

  18. Increase in platinum group elements in Mexico City as revealed from growth rings of Taxodium mucronatum ten.

    PubMed

    Morton-Bermea, Ofelia; Beramendi-Orosco, Laura; Martínez-Reyes, Ángeles; Hernández-Álvarez, Elizabeth; González-Hernández, Galia

    2016-02-01

    Tree rings may be used as indicators of contamination events providing information on the chronology and the elemental composition of the contamination. In this framework, we report PGEs enrichment in growth rings of Taxodium mucronatum ten for trees growing in the central area of Mexico City as compared to trees growing in a non-urban environment. Concentrations of PGE were determined by ICP-MS analysis on microwave-digested tree rings. The element found in higher concentrations was Pd (1.13-87.98 μg kg(-1)), followed by Rh (0.28-36.81 μg kg(-1)) and Pt (0.106-7.21 μg kg(-1)). The concentration trends of PGEs in the tree-ring sequences from the urban area presented significant correlation values when comparing between trees (r between 0.618 and 0.98, P < 0.025) and between elements within individual trees (r between 0.76 and 0.994, P < 0.01). Furthermore, a clear increase was observed for rings after 1997, with enrichment of up to 60 times the mean concentration found for the sequence from the non-urban area and up to 40 times the mean concentration for the pre-1991 period in the urban trees. These results also demonstrate the feasibility of applying T. mucronatum ten to be used as a bioindicator of the increase in PGE in urban environments. PMID:25903068

  19. Parameterization of a multiagent system for roof edge detection: an application to growth ring detection on fish otoliths

    NASA Astrophysics Data System (ADS)

    Guillaud, Anne; Benzinou, Abdessalam; Troadec, Herve; Rodin, Vincent; Le Bihan, Jean

    2000-03-01

    In this paper we present a method of segmentation using a multiagent system, and an application to fish otolith growth ring detection. The otoliths images are composed of alternative concentric dark and light rings, the number of which increases with the age of the fish. Up to now, the identification of growth rings, for age estimation, is routinely achieved by human readers, but this task is tedious and depends on the reader's subjectivity. The system proposed here is composed of several agents whose individual task is to detect local extremes on a grayscale image. For this aim the agents are provided with sensors on the gray levels of the image. By computing the mean gray level of two sensors placed in front of it, the agent, if it searches for light rings (respectively dark) will decide to turn in the direction of the lighter (respectively darker) sensor. The path of the agents has been tested as a roof edge detector, using the Canny criteria: good detection, good localization, and low multiple response, in order to choose the best parameters ruling the agents behavior, according to the image structures. Tests have been first achieved on synthetic images, and then on otoliths images.

  20. Annual growth patterns of baldcypress (Taxodium distichum) along salinity gradients

    USGS Publications Warehouse

    Thomas, Brenda L.; Doyle, Thomas W.; Krauss, Ken W.

    2015-01-01

    The effects of salinity on Taxodium distichum seedlings have been well documented, but few studies have examined mature trees in situ. We investigated the environmental drivers of T. distichum growth along a salinity gradient on the Waccamaw (South Carolina) and Savannah (Georgia) Rivers. On each river, T. distichum increment cores were collected from a healthy upstream site (Upper), a moderately degraded mid-reach site (Middle), and a highly degraded downstream site (Lower). Chronologies were successfully developed for Waccamaw Upper and Middle, and Savannah Middle. Correlations between standardized chronologies and environmental variables showed significant relationships between T. distichum growth and early growing season precipitation, temperature, and Palmer Drought Severity Index (PDSI). Savannah Middle chronology correlated most strongly with August river salinity levels. Both lower sites experienced suppression/release events likely in response to local anthropogenic impacts rather than regional environmental variables. The factors that affect T. distichum growth, including salinity, are strongly synergistic. As sea-level rise pushes the freshwater/saltwater interface inland, salinity becomes more limiting to T. distichum growth in tidal freshwater swamps; however, salinity impacts are exacerbated by locally imposed environmental modifications.

  1. No evidence for consistent long-term growth stimulation of 13 tropical tree species: results from tree-ring analysis.

    PubMed

    Groenendijk, Peter; van der Sleen, Peter; Vlam, Mart; Bunyavejchewin, Sarayudh; Bongers, Frans; Zuidema, Pieter A

    2015-10-01

    The important role of tropical forests in the global carbon cycle makes it imperative to assess changes in their carbon dynamics for accurate projections of future climate-vegetation feedbacks. Forest monitoring studies conducted over the past decades have found evidence for both increasing and decreasing growth rates of tropical forest trees. The limited duration of these studies restrained analyses to decadal scales, and it is still unclear whether growth changes occurred over longer time scales, as would be expected if CO2 -fertilization stimulated tree growth. Furthermore, studies have so far dealt with changes in biomass gain at forest-stand level, but insights into species-specific growth changes - that ultimately determine community-level responses - are lacking. Here, we analyse species-specific growth changes on a centennial scale, using growth data from tree-ring analysis for 13 tree species (~1300 trees), from three sites distributed across the tropics. We used an established (regional curve standardization) and a new (size-class isolation) growth-trend detection method and explicitly assessed the influence of biases on the trend detection. In addition, we assessed whether aggregated trends were present within and across study sites. We found evidence for decreasing growth rates over time for 8-10 species, whereas increases were noted for two species and one showed no trend. Additionally, we found evidence for weak aggregated growth decreases at the site in Thailand and when analysing all sites simultaneously. The observed growth reductions suggest deteriorating growth conditions, perhaps due to warming. However, other causes cannot be excluded, such as recovery from large-scale disturbances or changing forest dynamics. Our findings contrast growth patterns that would be expected if elevated CO2 would stimulate tree growth. These results suggest that commonly assumed growth increases of tropical forests may not occur, which could lead to erroneous

  2. Ethylene evolution, radial growth and carbohydrate concentrations in Abies balsamea shoots ringed with Ethrel.

    PubMed

    Eklund, Leif; Little, C. H. Anthony

    1998-06-01

    The terminal (1-year-old) shoot of quiescent, 2-year-old Abies balsamea (L.) Mill. seedlings was either left untreated or ringed with 0, 1 or 10 mg Ethrel g(-1) lanolin. After 5 weeks of culture under environmental conditions favorable for growth, the shoots were harvested to measure ethylene evolution and carbohydrate concentrations by gas chromatography, and tracheid number and bark radial width by microscopy. In untreated shoots, the basal rate of ethylene evolution followed the order: cambial region > cortex + periderm = xylem + pith = needles. Wound-induced ethylene production was not detected until at least 4 h after excision, but was evident in all fractions 24 h after excision; the increase in wound-induced ethylene evolution followed the order: cambial region > cortex + periderm > xylem + pith > needles. Compared with untreated controls, the application of plain lanolin, which involved the removal of needles and periderm, increased bark radial width and wound-induced ethylene production by the cambial region and the cortex + periderm, but decreased cambial region concentrations of fructose, glucose and starch at the application point. At the application point, Ethrel concomitantly increased ethylene evolution from the cambial region and the cortex + periderm, tracheid number, bark radial width, and the cambial region concentrations of fructose, glucose, sucrose and starch. No effects of Ethrel treatment were detected above or below the application point, with the exception that the 10 mg g(-1) Ethrel treatment stimulated ethylene evolution and decreased starch concentration of the cambial region. The results indicate that: (1) the cambial region is the major source of endogenous ethylene in the 1-year-old shoot; (2) the magnitude of the difference in ethylene evolution between particular shoot fractions is different before and after the start of wound-induced ethylene production; (3) the Ethrel-induced increase in tracheid number and bark radial width at

  3. Population differentiation in tree-ring growth response of white fir (Abies concolor) to climate: Implications for predicting forest responses to climate change

    SciTech Connect

    Jensen, D.B.

    1993-10-01

    Forest succession models and correlative models have predicted 200--650 kilometer shifts in the geographic range of temperate forests and forest species as one response to global climate change. Few studies have investigated whether population differences may effect the response of forest species to climate change. This study examines differences in tree-ring growth, and in the phenotypic plasticity of tree-ring growth in 16-year old white fir, Abies concolor, from ten populations grown in four common gardens in the Sierra Nevada of California. For each population, tree-ring growth was modelled as a function of precipitation and degree-day sums. Tree-ring growth under three scenarios of doubled C0{sub 2} climates was estimated.

  4. Sensitivity of tree ring growth to local and large-scale climate variability in a region of Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Venegas-González, Alejandro; Chagas, Matheus Peres; Anholetto Júnior, Claudio Roberto; Alvares, Clayton Alcarde; Roig, Fidel Alejandro; Tomazello Filho, Mario

    2016-01-01

    We explored the relationship between tree growth in two tropical species and local and large-scale climate variability in Southeastern Brazil. Tree ring width chronologies of Tectona grandis (teak) and Pinus caribaea (Caribbean pine) trees were compared with local (Water Requirement Satisfaction Index—WRSI, Standardized Precipitation Index—SPI, and Palmer Drought Severity Index—PDSI) and large-scale climate indices that analyze the equatorial pacific sea surface temperature (Trans-Niño Index-TNI and Niño-3.4-N3.4) and atmospheric circulation variations in the Southern Hemisphere (Antarctic Oscillation-AAO). Teak trees showed positive correlation with three indices in the current summer and fall. A significant correlation between WRSI index and Caribbean pine was observed in the dry season preceding tree ring formation. The influence of large-scale climate patterns was observed only for TNI and AAO, where there was a radial growth reduction in months preceding the growing season with positive values of the TNI in teak trees and radial growth increase (decrease) during December (March) to February (May) of the previous (current) growing season with positive phase of the AAO in teak (Caribbean pine) trees. The development of a new dendroclimatological study in Southeastern Brazil sheds light to local and large-scale climate influence on tree growth in recent decades, contributing in future climate change studies.

  5. Stabilization of actin bundles by a dynamin 1/cortactin ring complex is necessary for growth cone filopodia.

    PubMed

    Yamada, Hiroshi; Abe, Tadashi; Satoh, Ayano; Okazaki, Nana; Tago, Shota; Kobayashi, Kinue; Yoshida, Yumi; Oda, Yoshiya; Watanabe, Masami; Tomizawa, Kazuhito; Matsui, Hideki; Takei, Kohji

    2013-03-01

    Dynamin GTPase, a key molecule in endocytosis, mechanically severs the invaginated membrane upon GTP hydrolysis. Dynamin functions also in regulating actin cytoskeleton, but the mechanisms are yet to be defined. Here we show that dynamin 1, a neuronal isoform of dynamin, and cortactin form ring complexes, which twine around F-actin bundles and stabilize them. By negative-staining EM, dynamin 1-cortactin complexes appeared as "open" or "closed" rings depending on guanine nucleotide conditions. By pyrene actin assembly assay, dynamin 1 stimulated actin assembly in mouse brain cytosol. In vitro incubation of F-actin with both dynamin 1 and cortactin led to the formation of long and thick actin bundles, on which dynamin 1 and cortactin were periodically colocalized in puncta. A depolymerization assay revealed that dynamin 1 and cortactin increased the stability of actin bundles, most prominently in the presence of GTP. In rat cortical neurons and human neuroblastoma cell line, SH-SY5Y, both dynamin 1 and cortactin localized on actin filaments and the bundles at growth cone filopodia as revealed by immunoelectron microscopy. In SH-SY5Y cell, acute inhibition of dynamin 1 by application of dynamin inhibitor led to growth cone collapse. Cortactin knockdown also reduced growth cone filopodia. Together, our results strongly suggest that dynamin 1 and cortactin ring complex mechanically stabilizes F-actin bundles in growth cone filopodia. Thus, the GTPase-dependent mechanochemical enzyme property of dynamin is commonly used both in endocytosis and regulation of F-actin bundles by a dynamin 1-cortactin complex. PMID:23467367

  6. Benchmarks for Expected Annual Academic Growth for Students in the Bottom Quartile of the Normative Distribution

    PubMed Central

    Scammacca, Nancy K.; Fall, Anna-Mária; Roberts, Greg

    2015-01-01

    Effect sizes are commonly reported for the results of educational interventions. However, researchers struggle with interpreting their magnitude in a way that transcends generic guidelines. Effect sizes can be interpreted in a meaningful context by benchmarking them against typical growth for students in the normative distribution. Such benchmarks are not currently available for students in the bottom quartile. This report remedies this by providing a comparative context for interventions involving these students. Annual growth effect sizes for K–12 students were computed from nationally normed assessments and a longitudinal study of students in special education. They reveal declining growth over time, especially for reading and math. These results allow researchers to better interpret the effects of their interventions and help practitioners by quantifying typical growth for struggling students. More longitudinal research is needed to show growth trajectories for students in the bottom quartile. PMID:26726300

  7. Comparison of signaling interactions determining annual and perennial plant growth in response to low temperature

    PubMed Central

    Wingler, Astrid

    2015-01-01

    Low temperature inhibits plant growth despite the fact that considerable rates of photosynthetic activity can be maintained. Instead of lower rates of photosynthesis, active inhibition of cell division and expansion is primarily responsible for reduced growth. This results in sink limitation and enables plants to accumulate carbohydrates that act as compatible solutes or are stored throughout the winter to enable re-growth in spring. Regulation of growth in response to temperature therefore requires coordination with carbon metabolism, e.g., via the signaling metabolite trehalose-6-phosphate. The phytohormones gibberellin (GA) and jasmonate (JA) play an important role in regulating growth in response to temperature. Growth restriction at low temperature is mainly mediated by DELLA proteins, whose degradation is promoted by GA. For annual plants, it has been shown that the GA/DELLA pathway interacts with JA signaling and C-repeat binding factor dependent cold acclimation, but these interactions have not been explored in detail for perennials. Growth regulation in response to seasonal factors is, however, particularly important in perennials, especially at high latitudes. In autumn, growth cessation in trees is caused by shortening of the daylength in interaction with phytohormone signaling. In perennial grasses seasonal differences in the sensitivity to GA may enable enhanced growth in spring. This review provides an overview of the signaling interactions that determine plant growth at low temperature and highlights gaps in our knowledge, especially concerning the seasonality of signaling responses in perennial plants. PMID:25628637

  8. Constrained growth flips the direction of optimal phenological responses among annual plants.

    PubMed

    Lindh, Magnus; Johansson, Jacob; Bolmgren, Kjell; Lundström, Niklas L P; Brännström, Åke; Jonzén, Niclas

    2016-03-01

    Phenological changes among plants due to climate change are well documented, but often hard to interpret. In order to assess the adaptive value of observed changes, we study how annual plants with and without growth constraints should optimize their flowering time when productivity and season length changes. We consider growth constraints that depend on the plant's vegetative mass: self-shading, costs for nonphotosynthetic structural tissue and sibling competition. We derive the optimal flowering time from a dynamic energy allocation model using optimal control theory. We prove that an immediate switch (bang-bang control) from vegetative to reproductive growth is optimal with constrained growth and constant mortality. Increasing mean productivity, while keeping season length constant and growth unconstrained, delayed the optimal flowering time. When growth was constrained and productivity was relatively high, the optimal flowering time advanced instead. When the growth season was extended equally at both ends, the optimal flowering time was advanced under constrained growth and delayed under unconstrained growth. Our results suggests that growth constraints are key factors to consider when interpreting phenological flowering responses. It can help to explain phenological patterns along productivity gradients, and links empirical observations made on calendar scales with life-history theory. PMID:26548947

  9. Understanding the growth rate patterns of ion Bernstein instabilities driven by ring-like proton velocity distributions

    NASA Astrophysics Data System (ADS)

    Min, Kyungguk; Liu, Kaijun

    2016-04-01

    Fast magnetosonic waves in Earth's inner magnetosphere, which have as their source ion Bernstein instabilities, are driven by hot proton velocity distributions (fp) with ∂fp(v⊥)/∂v⊥>0. Two typical types of distributions with such features are ring and shell velocity distributions. Both have been used in studies of ion Bernstein instabilities and fast magnetosonic waves, but the differences between instabilities driven by the two types of distributions have not been thoroughly addressed. The present study uses linear kinetic theory to examine and understand these differences. It is found that the growth rate pattern is primarily determined by the cyclotron resonance condition and the structure of the velocity distribution in gyroaveraged velocity space. For ring-driven Bernstein instabilities, as the parallel wave number (k∥) increases, the discrete unstable modes approximately follow the corresponding proton cyclotron harmonic frequencies while they become broader in frequency space. At sufficiently large k∥, the neighboring discrete modes merge into a continuum. In contrast, for shell-driven Bernstein instabilities, the curved geometry of the shell velocity distribution in gyroaveraged velocity space results in a complex alternating pattern of growth and damping rates in frequency and wave number space and confines the unstable Bernstein modes to relatively small k∥. In addition, when k∥ increases, the unstable modes are no longer limited to the proton cyclotron harmonic frequencies. The local growth rate peak near an exact harmonic at small k∥ bifurcates into two local peaks on both sides of the harmonic when k∥ becomes large.

  10. Do tree ring chronologies have missing rings that distort volcanic cooling signal?: Fixing tree ring chronologies yields closer agreement with models

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-09-01

    Climate models generally show that when a massive volcano erupts, scattering reflective aerosols across the globe, the planet's temperature declines for up to a few years. However, when researchers look at reconstructed temperature records built on annual tree ring measurements, this volcanic cooling often appeared much weaker than expected or was nonexistent. In a new study reanalyzing regional tree ring growth records, Mann et al. provide a possible explanation for the absence of the cooling effect.

  11. Sub-annual Fluctuations in Water Sources Utilised by Mediterranean RiparianTrees Determined Through Highly Resolved Oxygen Isotope Analysis of Tree-ring Cellulose

    NASA Astrophysics Data System (ADS)

    Sargeant, C. I.; Singer, M. B.

    2014-12-01

    The sensitivity of trees to water availability within their rooting zones is a major determinant of tree and forest health. Yet, we have a poor understanding of subterranean water availability and its fluctuations due to climate. Such shortcomings limit our ability to predict how climatic variability will impact water availability to trees, and corresponding forest health. Understanding of water partitioning within the 'critical zone' of riparian areas are particularly lacking, especially in the vulnerable Mediterranean climate regimes. A substantial body of research uses isotope dendrochronology to assess riparian forest-water relations at annual (tree-ring) timescales, which integrate variability in seasonal hydrology. However, the sub-annual variations in water availability have been largely overlooked, which may have important ramifications for riparian ecohydrology. We present a new method for determining the sub-annual hydrologic variability within a floodplain forest using two co-occurring Mediterranean tree species along the Rhône River, southern France. We conducted oxygen isotope (δ18O) analysis of cellulose for 11 microslices within each tree ring to detect sub-annual patterns in δ18O that reflect the variability in hydrological partitioning. We back-calculated the seasonal time series of source waters used by the trees via a mechanistic model. Differences in rooting between the species allow us to constrain fluctuations in water availability and use between the vadose and phreatic zones. The two different species of streamside trees use distinct water sources and their seasonal patterns of water use are also fundamentally different. We develop strong links between these sub-annual patterns of δ18O signatures and the climatic characteristics of the hydrological year. We also present isotopic analyses of source waters from the vadose and phreatic zones, precipitation, and the Rhône to bolster our interpretations of water partitioning. This research

  12. Confined growth of carbon nanoforms in one-dimension by fusion of anthracene rings inside the pores of MCM-41

    NASA Astrophysics Data System (ADS)

    Bosch-Navarro, Concha; Coronado, Eugenio; Martí-Gastaldo, Carlos; Amorós, Pedro

    2014-06-01

    We report a simple two-step procedure that uses anthracene, a cheap polyaromatic hydrocarbon with low melting point, as a molecular precursor to produce carbon nanoforms (CNFs). First, we describe the chemical synthesis of graphite from the fusion of anthracene rings at relatively low temperature (520 °C) followed by cyclodehydrogenation. Next, we extend this protocol to the synthesis of CNFs by confining the molecular precursor in a mesoporous host like MCM-41. The confined environment favors one-dimensional growth of CNFs with sizes controlled by the pores of the mesoporous host.We report a simple two-step procedure that uses anthracene, a cheap polyaromatic hydrocarbon with low melting point, as a molecular precursor to produce carbon nanoforms (CNFs). First, we describe the chemical synthesis of graphite from the fusion of anthracene rings at relatively low temperature (520 °C) followed by cyclodehydrogenation. Next, we extend this protocol to the synthesis of CNFs by confining the molecular precursor in a mesoporous host like MCM-41. The confined environment favors one-dimensional growth of CNFs with sizes controlled by the pores of the mesoporous host. Electronic supplementary information (ESI) available: Synthesis details, SEM and additional HR-TEM images, FT-IR spectra, EDAX microanalysis and pore distribution of loaded MCM41@anth. See DOI: 10.1039/c3nr06669j

  13. Annual Precipitation since A.D. 1460 reconstructed from the juniper growth of Qilian Mountains

    NASA Astrophysics Data System (ADS)

    Tian, Q.

    2009-04-01

    We present a century-scale annual precipitation reconstruction from previous August to current July over the past 540 years based on a tree ring-width chronology developed from juniper (Juniperus przewalskii Kom) on the Qilian Mountains. The reconstruction is verified with dependent data, and accounts for 41% of the instrument data variance during their common period (1960-2000). The full reconstruction indicates that the regional precipitation variability is relative stable except for the significant wetter epoch (1680-1760 A.D.) and an extreme drought event in the late 1920 over a large geographic area in northwestern China, which is corroborated by other paleoclimatic indicators. The wavelet analysis reveals the strong low frequency cycles (2.8, 2.1-2.6, 4.5, 5.5-6.1 yr) on the whole reconstructed period. The cycle of 16 yr is also examined, but it is discontinuous for the whole period. Overall, our reconstruction not only extends the regional precipitation history, and provides the valuable information to understand some proposed climate forcing. Keyword: Tree-ring Width Index Precipitation Qilian Mountains

  14. Radiocarbon content in the annual tree rings during last 150 years and time variation of cosmic rays

    NASA Technical Reports Server (NTRS)

    Kocharov, G. E.; Metskvarishvili, R. Y.; Tsereteli, S. L.

    1985-01-01

    The results of the high accuracy measurements of radiocarbon abundance in precisely dated tree rings in the interval 1800 to 1950 yrs are discussed. Radiocarbon content caused by solar activity is established. The temporal dependence of cosmic rays is constructed, by use of radio abundance data.

  15. Validating Annual Growth Bands of Deep-Sea Black Corals and Calculating Ocean Reservoir Ages in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Roark, E. B.; Mohon, M. L.; Prouty, N.; Guillemette, R. N.; Fallon, S.; Ross, S. W.

    2015-12-01

    Deep-sea black corals (Leiopathes sp.) are long-lived (up to 4,000 yrs old), and grow in a tree-like fashion depositing growth rings in their skeleton. Scanning electron microscopy at 900x magnification was used to image thin sections and identify peaks in iodine intensity using energy dispersive x-ray spectroscopy in three specimens from the Gulf of Mexico. Age determination by counting visual growth bands and iodine peaks were compared to both radiocarbon and U/Th-derived ages. The first specimen (GOM-JSL04-4734-BC1) has an iodine peak count age of 695 ±70, and growth band age of 785 ± 80 which compare quite well to the radiocarbon age of 670 ±40 years and a U/Th age of 780 ±16 years. There was similar agreement between the radiocarbon ages (1399 ±30 and 670 ±35 years) and the iodine peak count ages (1240 ±125 and 715±70 years) for the remaining two specimens with growth rates ranging from 11 ±3 to 16 ±2 µm yr-1 for all 3 specimens. Using the independent (iodine derived) age models in conjunction with the radiocarbon data, a high resolution ocean reservoir age record was developed for the last 600 years. Reservoir ages varied from 120 to 550 14C years on decadal to centennial time scales. The modern reservoir age in the GOM is 235 ±11 14C years. The preferred explanation for the variability found in these reservoir ages is related to changes in the strength of the Yucatan Current. This novel approach combines the identification of growth bands captured in high-resolution SEM in combination with synchronous peaks in skeleton iodine composition and is the first to validate that both can be used as annual chronometers. Using the independent iodine age models in conjunction with the radiocarbon records, ocean reservoir age records can be developed for the last ~500 to 1000 years.

  16. [Tree-ring growth responses of Mongolian oak (Quercus mongolica) to climate change in southern northeast: a case study in Qianshan Mountains].

    PubMed

    Teng, Li; Xing-Yuan, He; Zhen-Ju, Chen

    2014-07-01

    Mongolian oak is one of the most important broad-leaved tree species in forests, Northeast China. Based on the methodology of dendrochronology, the variations of tree ring radial growth of Mongolian oak in Qianshan Mountains, south of Northeast China, were analyzed. Combined with the temperature and precipitation data from meteorological stations since 1951, the relationships between standardized tree ring width chronology and main climatic factors were analyzed. In this region, the precipitation between April and July of the current year had an significant relationship with the tree ring width of Mongolian oak, and was the main factor limiting the radial growth. The extreme maximum temperature of May was also a key factor influencing the tree ring width, which had a significant on the tree ring width of Mongolian oak. The precipitation in April had a significant and stable relationship with the growth of Mongolian oak since the 1950s. The 'divergence problem' was found in the study area, which the sensitivity of tree growth to summer temperature reduced since the 1980s. The tree growth response to temperature showed a seasonal change from summer to spring. PMID:25345030

  17. Traffic pollution affects P. pinea growth according to tree ring width and C and N isotopic composition

    NASA Astrophysics Data System (ADS)

    Battipaglia, Giovanna; Marzaioli, Fabio; Lubritto, Carmine; Altieri, Simona; Strumia, Sandro; Cherubini, Paolo; Cotrufo, M. Francesca

    2010-05-01

    Urbanization and industrialization are rapidly growing, as a consequence roads and their associated vehicular traffic exerts major and increasing impacts on adjacent ecosystems. Various studies have shown the impact of vehicle exhausts on road side vegetation through their visible and non-visible effects (Farmer and Lyon 1977, Sarkar et al., 1986, Angold 1997, Nuhoglu 2005) but, presently there is little known about the long term effect of air pollution on vegetation and on trees, in particular. Developing proxies for atmospheric pollution that would be used to identify the physiological responses of trees under roadside car exhaust pollution stress is needed. In this context we propose a novel method to determine the effect of car exhaust pollution on tree growth, coupling classical dendrochronological analyses and analyses of 15N and 13C in tree rings, soils and leaves with tree ring radiocarbon (14C) data. Pinus pinea individuals, adjacent to main roads in the urban area of Caserta (South Italy) and exposed to large amounts of traffic exhausts since 1980, were sampled and the time-related trend in the growth residuals was estimated. We found a consistent decrease in the ring width starting from 1980, with a slight increase in δ13C value, which was considered to be a consequence of environmental stress. No clear pattern was identified in δ15N, while an increasing effect of the fossil fuel dilution on the atmospheric bomb-enriched 14C background was detected in tree rings, as a consequence of the increase in traffic exhausts. Our findings suggest that radiocarbon is a very sensitive tool to investigate small-scale (i.e. traffic exhaust at the level crossing) and large-scale (urban area pollution) induced disturbances. References Angold PG. Impact of a road upon adjacent heathland vegetations: effect on plant species compositions. J Appl Ecol 1997; 34 (2): 409-417. Farmer JC, Lyon TDB. Lead in Glasgow street dirt and soil. Sci Tot Environ 1977; 8: 89-93. Nuhoglu

  18. Relationship between the growth of the ring current and the interplanetary quantity. [solar wind energy-magnetospheric coupling parameter correlation with substorm AE index

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1979-01-01

    Akasofu (1979) has reported that the interplanetary parameter epsilon correlates reasonably well with the magnetospheric substorm index AE; in the first approximation, epsilon represents the solar wind coupled to the magnetosphere. The correlation between the interplanetary parameter, the auroral electrojet index and the ring current index is examined for three magnetic storms. It is shown that when the interplanetary parameter exceeds the amount that can be dissipated by the ionosphere in terms of the Joule heat production, the excess energy is absorbed by the ring current belt, producing an abnormal growth of the ring current index.

  19. Crystal growth mechanisms in miarolitic cavities in the Lake George ring complex and vicinity, Colorado

    USGS Publications Warehouse

    Kile, D.E.; Eberl, D.D.

    1999-01-01

    The Crystal Peak area of the Pikes Peak batholith, near Lake George in central Colorado, is world-renowned for its crystals of amazonite (the blue-green variety of microcline) and smoky quartz. Such crystals, collected from individual miarolitic pegmatites, have a remakably small variation in crystal size within each pegmatite, and the shapes of plots of their crystal size distributions (CSDs) are invariably lognormal or close to lognormal in all cases. These observations are explained by a crystal growth mechanism that was governed initially by surface-controlled kinetics, during which crystals tended to grow larger in proportion to their size, thereby establishing lognormal CSDs. Surface-controlled growth was followed by longer periods of supply controlled growth, during which growth rate was predominantly size-independent, consequently preserving the lognormal shapes of the CSDs and the small size variation. The change from surface- to supply controlled growth kinetics may have resulted from an increasing demand for nutrients that exceeded diffusion limitations of the system. The proposed model for crystal growth in this locality appears to be common in the geologic record, and can be used with other information, such as isotopic data, to deduce physico-chemical conditions during crystal formation.

  20. Emittance growth in heavy ion rings due to effects of space charge and dispersion

    SciTech Connect

    Barnard, J.J., LLNL

    1998-06-03

    We review the derivation of moment equations which include the effects of space charge and dispersion in bends first presented in ref [1]. These equations generalize the familiar envelope equations to include the dispersive effects of bends. We review the application of these equations to the calculation of the change in emittance resulting from a sharp transition from a straight section to a bend section, using an energy conservation constraint. Comparisons of detailed 2D and 3D simulations of intense beams in rings using the WARP code (refs [2,3]) are made with results obtained from the moment equations. We also compare the analysis carried out in ref [1], to more recent analyses, refs [4,5]. We further examine self-consistent distributions of beams in bends and discuss the relevance of these distributions to the moment equation formulation.

  1. Annual Glyphosate Treatments Alter Growth of Unaffected Bentgrass (Agrostis) Weeds and Plant Community Composition

    PubMed Central

    Ahrens, Collin W.; Auer, Carol A.

    2012-01-01

    Herbicide resistance is becoming more common in weed ecotypes and crop species including turfgrasses, but current gaps in knowledge limit predictive ecological risk assessments and risk management plans. This project examined the effect of annual glyphosate applications on the vegetative growth and reproductive potential of two weedy bentgrasses, creeping bentgrass (CB) and redtop (RT), where the glyphosate resistance (GR) trait was mimicked by covering the bentgrass plants during glyphosate application. Five field plots were studied in habitats commonly inhabited by weedy bentgrasses including an agricultural hayfield, natural meadow, and wasteland. Results showed that annual glyphosate treatment improved bentgrass survivorship, vegetative growth, and reproductive potential compared with bentgrass in unsprayed subplots. In the second year of growth, RT plants had an 86-fold increase in flower number in glyphosate-treated subplots versus controls, while CB plants had a 20-fold increase. At the end of the three year study, plant community composition had changed in glyphosate-treated subplots in hayfield and meadow plots compared to controls. Soils in subplots receiving glyphosate had higher nitrate concentrations than controls. This is the first study to mimic the GR trait in bentgrass plants with the goal of quantifying bentgrass response to glyphosate selection pressure and understanding the impacts on surrounding plant communities. PMID:23226530

  2. Annual glyphosate treatments alter growth of unaffected bentgrass (Agrostis) weeds and plant community composition.

    PubMed

    Ahrens, Collin W; Auer, Carol A

    2012-01-01

    Herbicide resistance is becoming more common in weed ecotypes and crop species including turfgrasses, but current gaps in knowledge limit predictive ecological risk assessments and risk management plans. This project examined the effect of annual glyphosate applications on the vegetative growth and reproductive potential of two weedy bentgrasses, creeping bentgrass (CB) and redtop (RT), where the glyphosate resistance (GR) trait was mimicked by covering the bentgrass plants during glyphosate application. Five field plots were studied in habitats commonly inhabited by weedy bentgrasses including an agricultural hayfield, natural meadow, and wasteland. Results showed that annual glyphosate treatment improved bentgrass survivorship, vegetative growth, and reproductive potential compared with bentgrass in unsprayed subplots. In the second year of growth, RT plants had an 86-fold increase in flower number in glyphosate-treated subplots versus controls, while CB plants had a 20-fold increase. At the end of the three year study, plant community composition had changed in glyphosate-treated subplots in hayfield and meadow plots compared to controls. Soils in subplots receiving glyphosate had higher nitrate concentrations than controls. This is the first study to mimic the GR trait in bentgrass plants with the goal of quantifying bentgrass response to glyphosate selection pressure and understanding the impacts on surrounding plant communities. PMID:23226530

  3. Engelmann spruce tree-ring chronologies from Fraser Experimental Forest, Colorado: Potential for a long-term temperature reconstruction in the central Rocky Mountains

    SciTech Connect

    Brown, P.M.; Shepperd, W.D.

    1995-12-31

    Tree-ring width chronologies from Engelmann spruce at two treeline sites in the central Rocky Mountains contain similar high and low frequency patterns in ring width, indicative of regional climate control on tree growth. Comparisons of annual ring widths with instrumental climate data show relationships with late spring temperature fluctuations on annual to century time scales. Ring width patterns in the earliest dated trees at one of the sites also infers upward migration in treeline at the site around A.D. 1250. No unusual growth increases were seen in recent years, suggesting that these trees have not recorded warmer conditions possibly associated with global climate change.

  4. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry

    2014-03-01

    Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

  5. miR-762 promotes porcine immature Sertoli cell growth via the ring finger protein 4 (RNF4) gene

    PubMed Central

    Ma, Changping; Song, Huibin; Yu, Lei; Guan, Kaifeng; Hu, Pandi; Li, Yang; Xia, Xuanyan; Li, Jialian; Jiang, Siwen; Li, Fenge

    2016-01-01

    A growing number of reports have revealed that microRNAs (miRNAs) play critical roles in spermatogenesis. Our previous study showed that miR-762 is differentially expressed in immature and mature testes of Large White boars. Our present data shows that miR-762 directly binds the 3′ untranslated region (3′UTR) of ring finger protein 4 (RNF4) and down-regulates RNF4 expression. A single nucleotide polymorphism (SNP) in the RNF4 3′UTR that is significantly associated with porcine sperm quality traits leads to a change in the miR-762 binding ability. Moreover, miR-762 promotes the proliferation of and inhibits apoptosis in porcine immature Sertoli cells, partly by accelerating DNA damage repair and by reducing androgen receptor (AR) expression. Taken together, these findings suggest that miR-762 may play a role in pig spermatogenesis by regulating immature Sertoli cell growth. PMID:27596571

  6. miR-762 promotes porcine immature Sertoli cell growth via the ring finger protein 4 (RNF4) gene.

    PubMed

    Ma, Changping; Song, Huibin; Yu, Lei; Guan, Kaifeng; Hu, Pandi; Li, Yang; Xia, Xuanyan; Li, Jialian; Jiang, Siwen; Li, Fenge

    2016-01-01

    A growing number of reports have revealed that microRNAs (miRNAs) play critical roles in spermatogenesis. Our previous study showed that miR-762 is differentially expressed in immature and mature testes of Large White boars. Our present data shows that miR-762 directly binds the 3' untranslated region (3'UTR) of ring finger protein 4 (RNF4) and down-regulates RNF4 expression. A single nucleotide polymorphism (SNP) in the RNF4 3'UTR that is significantly associated with porcine sperm quality traits leads to a change in the miR-762 binding ability. Moreover, miR-762 promotes the proliferation of and inhibits apoptosis in porcine immature Sertoli cells, partly by accelerating DNA damage repair and by reducing androgen receptor (AR) expression. Taken together, these findings suggest that miR-762 may play a role in pig spermatogenesis by regulating immature Sertoli cell growth. PMID:27596571

  7. Growth of ring ripple in a collisionless plasma in relativistic-ponderomotive regime and its effect on stimulated Raman backscattering process

    SciTech Connect

    Rawat, Priyanka; Purohit, Gunjan; Gauniyal, Rakhi

    2014-06-15

    A theoretical and numerical study has been made of the propagation of a ring rippled laser beam in collisionless plasma with dominant relativistic ponderomotive nonlinearity and its effect on the excitation of electron plasma wave and stimulated Raman backscattering process. The growth of ring ripple, riding on an intense Gaussian laser beam in plasma has also been studied. A paraxial-ray and WKB approximation has been invoked to understand the nature of propagation of the ring rippled Gaussian laser beam in plasma, electron plasma wave and back reflectivity under the influence of both nonlinearities. The growth rate and focusing of a ring rippled beam is found to be considerably affected by the power of the main beam and the phase angle between the electric vectors of the main beam and the ring ripple. It has also been observed that the focusing is released by the coupling of relativistic and ponderomotive nonlinearities, which significantly affected the dynamics of the excitation of electron plasma wave and back reflectivity of stimulated Raman scattering (SRS). Due to the strong coupling between ring rippled laser beam and the excited electron plasma wave, back reflectivity of SRS is enhanced. It has been observed from the computational results that the effect of the increased intensity leads to suppression of SRS back reflectivity. The results have been presented for established laser and plasma parameters.

  8. Design and synthesis of benzoylphenylureas with fluorinated substituents on the aniline ring as insect growth regulators.

    PubMed

    Sun, Ranfeng; Liu, Yuxiu; Zhang, Yonglin; Xiong, Lixia; Wang, Qingmin

    2011-03-23

    Enormous numbers of synthetic fluorine-containing compounds have been widely used in a variety of fields, especially in drug and pesticide design. To find novel insect growth regulators, a series of benzoylphenylureas with fluorinated substituents were designed and synthesized. The results of larvicidal activities of those novel fluoro-substituted benzoylphenylureas against oriental armyworm and mosquito revealed that most compounds exhibited excellent activities. It is worth mentioning that compounds 3 and 6 exhibited higher activities against oriental armyworm and mosquito than commercial Hexaflumuron. It can be further seen that the insecticidal activities would increase significantly by introducing fluorinated substituents into the structure of the designed benzoylphenylureas. PMID:21366291

  9. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.

    2011-07-01

    Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

  10. Tree-ring stable isotopes record the impact of a foliar fungal pathogen on CO2 assimilation and growth in Douglas-fir

    EPA Science Inventory

    Swiss needle cast (SNC) is a fungal disease of Douglas-fir (Pseudotsuga menziesii) that has recently become prevalent in coastal areas of the Pacific Northwest. We used growth measurements and stable isotopes of carbon and oxygen in tree-rings of Douglas-fir and a non-susceptible...

  11. Studies and calculations of transverse emittance growth in high-energy proton storage rings

    SciTech Connect

    Mane, S.R.; Jackson, G.

    1989-03-01

    In the operation of proton-antiproton colliders, an important goal is to maximize the integrated luminosity. During such operations in the Fermilab Tevatron, the transverse beam emittances were observed to grow unexpectedly quickly, thus causing a serious reduction of the luminosity. We have studied this phenomenon experimentally and theoretically. A formula for the emittance growth rate, due to random dipole kicks, is derived. In the experiment, RF phase noise of known amplitude was deliberately injected into the Tevatron to kick the beam randomly, via dispersion at the RF cavities. Theory and experiment are found to agree reasonably well. We also briefly discuss the problem of quadrupole kicks. 14 refs., 2 figs., 3 tabs.

  12. Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth

    PubMed Central

    Loyer, Nicolas; Kolotuev, Irina; Pinot, Mathieu; Le Borgne, Roland

    2015-01-01

    Intercellular bridges called “ring canals” (RCs) resulting from incomplete cytokinesis play an essential role in intercellular communication in somatic and germinal tissues. During Drosophila oogenesis, RCs connect the maturing oocyte to nurse cells supporting its growth. Despite numerous genetic screens aimed at identifying genes involved in RC biogenesis and maturation, how RCs anchor to the plasma membrane (PM) throughout development remains unexplained. In this study, we report that the clathrin adaptor protein 1 (AP-1) complex, although dispensable for the biogenesis of RCs, is required for the maintenance of the anchorage of RCs to the PM to withstand the increased membrane tension associated with the exponential tissue growth at the onset of vitellogenesis. Here we unravel the mechanisms by which AP-1 enables the maintenance of RCs’ anchoring to the PM during size expansion. We show that AP-1 regulates the localization of the intercellular adhesion molecule E-cadherin and that loss of AP-1 causes the disappearance of the E-cadherin–containing adhesive clusters surrounding the RCs. E-cadherin itself is shown to be required for the maintenance of the RCs’ anchorage, a function previously unrecognized because of functional compensation by N-cadherin. Scanning block-face EM combined with transmission EM analyses reveals the presence of interdigitated, actin- and Moesin-positive, microvilli-like structures wrapping the RCs. Thus, by modulating E-cadherin trafficking, we show that the sustained E-cadherin–dependent adhesion organizes the microvilli meshwork and ensures the proper attachment of RCs to the PM, thereby counteracting the increasing membrane tension induced by exponential tissue growth. PMID:26424451

  13. Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth.

    PubMed

    Loyer, Nicolas; Kolotuev, Irina; Pinot, Mathieu; Le Borgne, Roland

    2015-10-13

    Intercellular bridges called "ring canals" (RCs) resulting from incomplete cytokinesis play an essential role in intercellular communication in somatic and germinal tissues. During Drosophila oogenesis, RCs connect the maturing oocyte to nurse cells supporting its growth. Despite numerous genetic screens aimed at identifying genes involved in RC biogenesis and maturation, how RCs anchor to the plasma membrane (PM) throughout development remains unexplained. In this study, we report that the clathrin adaptor protein 1 (AP-1) complex, although dispensable for the biogenesis of RCs, is required for the maintenance of the anchorage of RCs to the PM to withstand the increased membrane tension associated with the exponential tissue growth at the onset of vitellogenesis. Here we unravel the mechanisms by which AP-1 enables the maintenance of RCs' anchoring to the PM during size expansion. We show that AP-1 regulates the localization of the intercellular adhesion molecule E-cadherin and that loss of AP-1 causes the disappearance of the E-cadherin-containing adhesive clusters surrounding the RCs. E-cadherin itself is shown to be required for the maintenance of the RCs' anchorage, a function previously unrecognized because of functional compensation by N-cadherin. Scanning block-face EM combined with transmission EM analyses reveals the presence of interdigitated, actin- and Moesin-positive, microvilli-like structures wrapping the RCs. Thus, by modulating E-cadherin trafficking, we show that the sustained E-cadherin-dependent adhesion organizes the microvilli meshwork and ensures the proper attachment of RCs to the PM, thereby counteracting the increasing membrane tension induced by exponential tissue growth. PMID:26424451

  14. Telemetry carrier ring and support

    NASA Technical Reports Server (NTRS)

    Wakeman, Thomas G. (Inventor)

    1992-01-01

    A telemetry carrier ring for use in a gas turbine engine includes an annular support ring connected to the engine and an annular carrier ring coupled to the support ring, each ring exhibiting different growth characteristics in response to thermal and mechanical loading. The carrier ring is coupled to the support ring by a plurality of circumferentially spaced web members which are relatively thin in an engine radial direction to provide a predetermined degree of radial flexibility. the web members have a circumferential width and straight axial line of action selected to transfer torque and thrust between the support ring and the carrier ring without substantial deflection. The use of the web members with radial flexibility provides compensation between the support ring and the carrier ring since the carrier ring grows at a different rate than the supporting ring.

  15. Rapid growth, early maturation and short generation time in African annual fishes

    PubMed Central

    2013-01-01

    Background Extreme environmental conditions can give rise to extreme adaptations. We document growth, sexual maturation and fecundity in two species of African annual fish inhabiting temporary savanna pools. Results Nothobranchius kadleci started to reproduce at the age of 17 days and size of 31 mm and Nothobranchius furzeri at 18 days and 32 mm. All four study populations demonstrated rapid growth rates of up to 2.72 mm/day (23.4% of their total length). Both species may produce diapausing embryos or embryos that are able to hatch in as few as 15 days, resulting in a minimum generation time as short as only one month. Incubation on the surface of damp peat moss results in high embryo survival (73%) and a high proportion of rapidly developing embryos (58%) that skip diapauses and hatch in less than 30 days. We further demonstrated that rapid growth and maturation do not compromise subsequent fecundity. Conclusions Our data suggest that both species have the most rapid sexual maturation and minimum generation time of any vertebrate species, and that rapid maturity does not involve paedogenesis. PMID:24007640

  16. Recent developments in annual growth lignocellulosics as reinforcing fillers in thermoplastics

    SciTech Connect

    Jacobson, R.E.; Caulfield, D.F.; Rowell, R.M.

    1995-11-01

    Recent interest in reducing the environmental impact of materials is leading to the development of newer agricultural based materials that can reduce the stress to the environment. Several billion pounds of fillers and reinforcements are used annually in the plastics industry and their use is likely to increase, to reduce the amount of plastics used in a product, with improved compounding technology and new coupling agents. The use of lignocellulosic fibers (eg. kenaf, jute, etc.) as reinforcing fillers in plastics has generated significant interest in recent years. The use of lignocellosic fibers permit the use of high volume fillings due to their lower densities and non-abrasive properties, and therefore reduces the use of plastics in a product. The specific tensile and flexural moduli of a 50% weight of glass fiber-PP injection molded composite and are superior to typical calcium carbonate or talc based PP composites. Results indicate that annual growth lignocellulosic wastes and fibers are viable reinforcing fillers as long as the right processing conditions and aids are used, and for applications where the higher water absorption of the agro-base fiber composite is not critical.

  17. Analysis of the differential response of five annuals to elevated CO sub 2 during growth

    SciTech Connect

    Garbutt, K. ); Williams, W.E. ); Bazzaz, F.A. )

    1990-06-01

    In order to investigate the effects, without competition, of CO{sub 2} on germination, growth, physiological response, and reproduction, the authors focussed on co-occurring species that are prominent members of an annual community in Illinois. Five species of old field annual plants - Abutilon theophrasti (C{sub 3}), Amaranthus retroflexus (C{sub 4}), Ambrosia artemisiifolia (C{sub 3}), Chenopodium album (C{sub 3}), and Setaria faberii (C{sub 4}) - were grown for their entire life cycle as individuals at CO{sub 2} concentration of 350 {mu}L/O, 500 {mu}L/L, and 700 {mu}L/L. Emergence time, growth rate, shoot water status, photosynthesis, conductance, flowering time, nitrogen content, and biomass and reproductive biomass were measured. There was no detectable effect of enhanced CO{sub 2} on timing of emergency in any of the species. The three levels of carbon dioxide concentration were shown to produce varying effects on remaining quantities measured in the five different plants. Some of these differences were not statistically significant. The response of most characters had a significant species {times} CO{sub 2} interaction. However, this was not simply caused by the C{sub 3}/C{sub 4} dichotomy. Reproductive biomass (seed, fruits, and flowers) increased with increasing CO{sub 2} in Amaranthus (C{sub 4}) and in Chenopodium and Ambrosia (both C{sub 3}), but there was no change in Setaria (C{sub 4}), and Abutilon (C{sub 3}) showed a peak at 500 {mu}L/L. Species of the same community differed in their response to CO{sub 2}, and these differences may help explain the outcome of competitive interactions among these species above ambient CO{sub 2} levels.

  18. Growth response of temperate mountain grasslands to inter-annual variations of snow cover duration

    NASA Astrophysics Data System (ADS)

    Choler, P.

    2015-02-01

    A remote sensing approach is used to examine the direct and indirect effects of snow cover duration and weather conditions on the growth response of mountain grasslands located above the tree line in the French Alps. Time-integrated normalized difference vegetation index (NDVIint), used as a surrogate for aboveground primary productivity, and snow cover duration were derived from a 13 year long time series of the Moderate Resolution Imaging Spectro-radiometer (MODIS). A regional-scale meteorological forcing that accounted for topographical effects was provided by the SAFRAN-Crocus-MEPRA model chain. A hierarchical path analysis was developed to analyze the multivariate causal relationships between forcing variables and proxies of primary productivity. Inter-annual variations in primary productivity were primarily governed by year-to-year variations in the length of the snow-free period and to a much lesser extent by temperature and precipitation during the growing season. A prolonged snow cover reduces the number and magnitude of frost events during the initial growth period but this has a negligeable impact on NDVIint as compared to the strong negative effect of a delayed snow melting. The maximum NDVI slightly responded to increased summer precipitation and temperature but the impact on productivity was weak. The period spanning from peak standing biomass to the first snowfall accounted for two thirds of NDVIint and this explained the high sensitivity of NDVIint to autumn temperature and autumn rainfall that control the timing of the first snowfall. The ability of mountain plants to maintain green tissues during the whole snow-free period along with the relatively low responsiveness of peak standing biomass to summer meteorological conditions led to the conclusion that the length of the snow-free period is the primary driver of the inter-annual variations in primary productivity of mountain grasslands.

  19. Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

    NASA Astrophysics Data System (ADS)

    Choler, P.

    2015-06-01

    A remote sensing approach is used to examine the direct and indirect effects of snow cover duration and weather conditions on the growth response of mountain grasslands located above the tree line in the French Alps. Time-integrated Normalized Difference Vegetation Index (NDVIint), used as a surrogate for aboveground primary productivity, and snow cover duration were derived from a 13-year long time series of the Moderate-resolution Imaging Spectroradiometer (MODIS). A regional-scale meteorological forcing that accounted for topographical effects was provided by the SAFRAN-CROCUS-MEPRA model chain. A hierarchical path analysis was developed to analyze the multivariate causal relationships between forcing variables and proxies of primary productivity. Inter-annual variations in primary productivity were primarily governed by year-to-year variations in the length of the snow-free period and to a much lesser extent by temperature and precipitation during the growing season. A prolonged snow cover reduces the number and magnitude of frost events during the initial growth period but this has a negligible impact on NDVIint as compared to the strong negative effect of a delayed snow melting. The maximum NDVI slightly responded to increased summer precipitation and temperature but the impact on productivity was weak. The period spanning from peak standing biomass to the first snowfall accounted for two-thirds of NDVIint and this explained the high sensitivity of NDVIint to autumn temperature and autumn rainfall that control the timing of the first snowfall. The ability of mountain plants to maintain green tissues during the whole snow-free period along with the relatively low responsiveness of peak standing biomass to summer meteorological conditions led to the conclusion that the length of the snow-free period is the primary driver of the inter-annual variations in primary productivity of mountain grasslands.

  20. Model-based analysis on the relationship between production and tree-ring growth in Japanese conifer-hardwood mixed forests

    NASA Astrophysics Data System (ADS)

    Koide, D.; Ito, A.

    2015-12-01

    Forest productivity is a basic and important component of terrestrial material flow and its importance increases according to recent climate warming and the increase in atmospheric-CO2 concentrations. Forest productivity study progresses through measurement by eddy-covariance data from flux tower and prediction by terrestrial ecosystem models. However, flux tower observation has spatiotemporal bias and limitation. On the other hand, tree-ring data have a close connection with forest ecosystem productivity. Compared to flux tower observation, we can collect tree-ring data from a larger number of sites and longer time scales. Comparisons between tree-ring observation and model-estimated productivity is important to reveal underlying mechanisms of forest ecosystem productivity and growth in wide spatiotemporal scale. This study aimed at revealing the relationship between temporal changes in tree-ring data and estimated forest ecosystem productivity in Japanese conifer-hardwood mixed forest. We also addressed climatic bias in the relationship by comparing between sites at different climatic conditions. Tree-ring data of Sakhalin spruce (Picea glehnii) were obtained from the International Tree Ring Data Bank. Six sites on the Hokkaido island (northern island of Japan) were selected for the present analysis. The Vegetation Integrated SImulator for Trace gasses (VISIT) model was validated by comparing with carbon flux data from Asia flux network sites. Past climatic parameters were obtained from ERA-20C reanalysis data from the European Center for Medium-range Weather Forecasts. Correlation between basal area increment and net ecosystem productivity was highest in the coldest site but this correlation weakened in warmer sites. This result implies that long-term growth trend was mainly restricted by cold stress associated with productivity reduction in colder sites but this factor is less important and other factors exert influence in warmer sites.

  1. Tree ring record chronicles major Mesoamerican droughts

    NASA Astrophysics Data System (ADS)

    Tretkoff, Ernie

    2011-05-01

    A new tree ring record chronicles major Mesoamerican droughts in the past millennium that may have contributed to the decline of some pre-Hispanic civilizations. Although there is other evidence of droughts during the past millennium, the paleoclimate record had gaps. Stahle et al. used core samples from Montezuma bald cypress trees found in Barranca de Amealco, Querétaro, Mexico, to develop a 1238-year tree ring chronology. They reconstructed the soil moisture record from the tree ring growth patterns. The new record provides the first dated, annually resolved climate record for Mexico and Central America spanning this time period.(Geophysical Research Letters, doi:10.1029/2010GL046472, 2011)

  2. The Influence of Precipitation-Driven Annual Plant Growth on Dust Emission in the Mojave Desert, USA

    NASA Astrophysics Data System (ADS)

    Urban, F. E.; Reynolds, R. L.; Fulton, R. E.

    2009-12-01

    Sparsely vegetated drylands are an important source for dust emission. However, little detail is known about dust generation in response to timing of precipitation and the consequent effects on soil and vegetation dynamics in these settings. This deficiency is especially acute at intermediate landscape scales, tens of meters to several hundred meters. It is essential to consider dust emission at this scale, because it links dust generation at scales of grains and wind tunnels with regional-scale dust examined using remotely sensed data from satellites. Three sites of slightly different geomorphic settings in the vicinity of Soda (dry) Lake were instrumented (in 1999) with meteorological and sediment transport sensors to measure wind erosion through saltating particle detection during high winds. Changes in vegetation in close proximity to the instrumented sites were bi-annually documented through measurements of plant type, cover, and repeat photographic imagery. Whereas high wind events are the dominant driver of saltation and dust emission, emissive conditions prevail only when annual plants are sparse or absent. Results show that wind erosion and dust emission at two study sites are highly variable and that such variability is dominantly related to vegetation type and cover as influenced by the amount and timing of antecedent precipitation. Secondary controls on dust emission are availability of new sediment related to flood deposits at the sites and seasonally differential wind strength. At sites where annual plants respond quickly and advantageously to precipitation, emissive conditions typically shut down because of vegetation growth within two to three months. This cover of annual plants, even when dead, persists in the desert landscape as a stabilizing agent for varying amounts of time, ten months to three years depending on the amount and vegetation type and subsequent input of precipitation and further annual plant growth. The lasting stabilization effect

  3. Measuring annual growth using written expression curriculum-based measurement: An examination of seasonal and gender differences.

    PubMed

    Keller-Margulis, Milena A; Mercer, Sterett H; Payan, Anita; McGee, Wendy

    2015-06-01

    The purpose of this study was to examine annual growth patterns and gender differences in written expression curriculum-based measurement (WE-CBM) when used in the context of universal screening. Students in second through fifth grade (n = 672) from 2 elementary schools that used WE-CBM as a universal screener participated in the study. Student writing samples were scored for production-dependent, production-independent, and accurate-production indicators. Results of latent growth models indicate that for most WE-CBM outcome indicators across most grade levels, average growth was curvilinear, with increasing curvilinearity on all indicators as grade level increased. Evidence of gender differences was mixed with girls having higher initial scores on all WE-CBM indicators except for total words written (second and third grades), correct minus incorrect writing sequences (fourth grade only), and percent correct writing sequences (second-fourth grades) where differences were not statistically significant. Despite differences in initial level, there were few gender differences in growth and limited overall between-student variability in linear slope. The results of this study extend research on annual patterns of growth and gender differences in WE-CBM by analyzing all 3 types of WE-CBM indicators, including upper elementary grades, and assessing skills more frequently (i.e., 4 to 5 times in 1 year) than in prior research on annual growth. The findings have implications for universal screening in WE-CBM and for understanding gender differences in writing performance. PMID:25133462

  4. Statistical methodologies for tree-ring research to understand the climate-growth relationships over time and space

    EPA Science Inventory

    The International Tree-Ring Database is a valuable resource for studying climate change and its effects on terrestrial ecosystems over time and space. We examine the statistical methods in current use in dendroclimatology and dendroecology to process the tree-ring data and make ...

  5. Nutrition and Child Growth and Development in Tunisia. Annual Progress Report, September 1, 1971--August 31, 1972.

    ERIC Educational Resources Information Center

    Young, Harben Boutourline

    This annual report of the Yale Project describes the progress made on the nutrition and growth study of Tunisian children from September 1, 1971 through August 31, 1972. The report details: (1) the progress in analysis of the cross-sectional study data, which was completed as of June 30, 1972, and (2) the development of the present longitudinal…

  6. Changes in Sahelian annual vegetation growth and phenology since 1960: A modeling approach

    NASA Astrophysics Data System (ADS)

    Pierre, C.; Grippa, M.; Mougin, E.; Guichard, F.; Kergoat, L.

    2016-08-01

    In semi-arid areas like the Sahel, vegetation is particularly sensitive to climate variability and can play an important role in surface-atmosphere coupling. After a wet period extending from 1950 to 1970, the Sahel experienced a severe drought in the 1970s and 1980s, followed by a partial recovery of rainfall and a "re-greening" of vegetation beginning in the 1990s. This study explores how the multidecadal variability of Sahelian rainfall and particularly the drought period have affected vegetation phenology and growth since 1960. The STEP model, which is specifically designed to simulate the Sahelian annual vegetation, including the dry season processes, is run over an area extending from 13°N to 18°N and from 20°W to 20°E. Mean values, interannual variability and phenological characteristics of the Sahelian annual grasslands simulated by STEP are in good agreement with MODIS derived production and phenology over the 2001-2014 period, which demonstrates the skill of the model and allows the analysis of vegetation changes and variability over the last 50 years. It was found that droughts in the 1970s and 1980s shortened the mean vegetation cycle and reduced its amplitude and that, despite the rainfall recovery since the 1990s, the current conditions for green and dry vegetation are still below pre-drought conditions. While the decrease in vegetation production has been largely homogeneous during droughts, vegetation recovery has been heterogeneous over the Sahel since 1990, with specific changes near the western coast and at the eastern edge of the West African monsoon area. Since 1970, the Sahel also experienced an increased interannual variability in vegetation mass and phenology. In terms of phenology, region-averaged End and Length of Season are the most variable, while maximum date and Start of Season are the least variable, although the latter displays a high variability locally.

  7. Intra-annual response of tree growth to climate in temperate forests: larger implications of fine-scale responses

    NASA Astrophysics Data System (ADS)

    McMahon, S.; Parker, G. G.

    2013-12-01

    Tree growth is a key component in the movement of carbon through terrestrial ecosystems. Although correlating annual growth rates to temperature an precipitation averages is the most common approach to extrapolating climate sensitivities, individual trees respond to weather at a much finer temporal scale. This response, further, is sensitive to many environmental factors and that sensitivity can depend on species, individual location in the species range, or size of the individual among other factors. Using weekly and bi-weekly measurements of dendrometer bands on 100 trees in three sites in the eastern US (Massachusetts, Virginia, and Maryland) over four years, we fit functional forms to intra-annual growth and compared patterns in productivity response to daily temperature and water balance information. We also determined phenological patterns in growth initiation, cessation, and maximum rate. We found that across size classes and species, trees respond to high temperatures and minor droughts by pausing in diameter increase. Although water retention may contribute some to this pattern, large differences in end-of-year biomass gain demonstrate a clear relationship between these pauses and overall annual carbon gain. Species did show some distinct patterns in this sensitivity and the overall phenology of growth. Further, the growing season as defined by when the majority of biomass increase actually occurred was much smaller than the leaf-out season indicating that droughts and heat-waves in a key subset of the green season can have a disproportionate effect on tree carbon uptake and forest carbon balance.

  8. Annual patterns within tree rings of the Arctic middle Eocene (ca. 45 Ma): Isotopic signatures of precipitation, relative humidity, and deciduousness

    NASA Astrophysics Data System (ADS)

    Jahren, A. Hope; Sternberg, Leonel S. L.

    2008-02-01

    The spectacular preservation of middle Eocene (ca. 45 Ma) woodallows for intraseason sampling of stable carbon, oxygen, andhydrogen in order to reconstruct the paleoseasonal environmentof this Arctic forest (paleolatitude 78.6° ± 1.6°N; present latitude 80° N). Carbon isotopes in bulk organicsand cellulose reveal striking annual patterns interpreted asthe seasonal switchover from stored to actively acquired carbonassociated with deciduous growth in these unusual conifers.Oxygen and hydrogen stable isotopes of cellulose and cellulosenitrate allow for the calculation of changes in relative humidityand in the isotopic value of plant-available water. Clear annualpatterns of increasing relative humidity resulting from tissuegrowth and concomitant transpiration are apparent, as is thesystematic increase in the reconstructed oxygen isotope valueof environmental water, reflecting progressively increasingtemperatures during the growing season.

  9. Etropus crossotus, an annual flatfish species; age and growth of the fringed flounder in South Carolina

    NASA Astrophysics Data System (ADS)

    Reichert, Marcel J. M.

    1998-12-01

    Fringed flounder, Etropus crossotus, a small flatfish common along the southeastern coast of the US, were collected along the South Carolina coast in the fall of 1992, and in the North Inlet estuary from August 1992 until July 1994. Standard length was 82% of total length and the relationship between standard length and wet weight showed near-isometric growth with no significant differences between males and females. Dry weight was 21% of wet weight and ash-free dry weight 14% of wet weight with no significant differences between sexes. Daily increments in the sagittal otoliths were used for age determination. No annual structures could be identified. The maximum age was about 14.5 months. Age-at-length was not different between the sexes. The relationship between age and length was exponential, with age (in days) equalling an e power of 4.242 + 0.135 × standard length (in cm). Back-calculated hatch dates and catches of early juveniles indicated a spawning season that lasted from March to October. Females started to be sexually mature at 7 to 7.5 cm standard length, but 50% maturity was reached at 8 to 8.5 cm. Females could grow to that size within one spawning season. Individuals hatched early in the spawning season could produce eggs in the latter portion of that season's spawning period.

  10. Growth and viability of Liaoning Cashmere goat hair follicles during the annual hair follicle cycle.

    PubMed

    Zhang, Q L; Li, J P; Chen, Y; Chang, Q; Li, Y M; Yao, J Y; Jiang, H Z; Zhao, Z H; Guo, D

    2014-01-01

    Here, we studied hair follicle development of Liaoning Cashmere goats. Every month for 1 year, skin samples were collected from five 1.5-year-old female goats, and made into paraffin sections. A number of parameters were measured of primary and secondary hair follicles via microscopic observation including follicle depth, hair bulb width, dermis and epidermis thickness, changes in follicle activity, and histology. The results showed the presence of three phases in the annual hair cycle: anagen, catagen, and telogen. Primary and secondary hair follicle depth varied across the months; however, no significant difference was obtained between adjacent months (P>0.05). Primary hair follicles had a bigger hair bulb width compared to secondary hair follicles; however, this difference declined during hair follicle developed in anagen. As hair follicle growth slowed, the hair bulb broadened, and hair root depth became shallower. During the entire hair cycle, hair follicle depth and dermis thickness were positively correlated; however, this relationship was not significant (P>0.05) for primary and secondary hair follicle density and the ratio of secondary hair follicle density and primary hair follicle density (S/P ratio). In addition, new and old primary hair follicles coexisted with secondary hair follicles. Finally, secondary hair follicles had a higher activity rate compared to primary hair follicle in adult Liaoning Cashmere goats in certain months. PMID:25036348

  11. iTREE: Long-term variability of tree growth in a changing environment - identifying physiological mechanisms using stable C and O isotopes in tree rings.

    NASA Astrophysics Data System (ADS)

    Siegwolf, R. T. W.; Buchmann, N.; Frank, D.; Joos, F.; Kahmen, A.; Treydte, K.; Leuenberger, M.; Saurer, M.

    2012-04-01

    Trees play are a critical role in the carbon cycle - their photosynthetic assimilation is one of the largest terrestrial carbon fluxes and their standing biomass represents the largest carbon pool of the terrestrial biosphere. Understanding how tree physiology and growth respond to long-term environmental change is pivotal to predict the magnitude and direction of the terrestrial carbon sink. iTREE is an interdisciplinary research framework to capitalize on synergies among leading dendroclimatologists, plant physiologists, isotope specialists, and global carbon cycle modelers with the objectives of reducing uncertainties related to tree/forest growth in the context of changing natural environments. Cross-cutting themes in our project are tree rings, stable isotopes, and mechanistic modelling. We will (i) establish a European network of tree-ring based isotope time-series to retrodict interannual to long-term tree physiological changes, (ii) conduct laboratory and field experiments to adapt a mechanistic isotope model to derive plant physiological variables from tree-ring isotopes, (iii) implement this model into a dynamic global vegetation model, and perform subsequent model-data validation exercises to refine model representation of plant physiological processes and (iv) attribute long-term variation in tree growth to plant physiological and environmental drivers, and identify how our refined knowledge revises predictions of the coupled carbon-cycle climate system. We will contribute to i) advanced quantifications of long-term variation in tree growth across Central Europe, ii) novel long-term information on key physiological processes that underlie variations in tree growth, and iii) improved carbon cycle models that can be employed to revise predictions of the coupled carbon-cycle climate system. Hence iTREE will significantly contribute towards a seamless understanding of the responses of terrestrial ecosystems to long-term environmental change, and ultimately

  12. Planetary rings

    SciTech Connect

    Greenberg, R.; Brahic, A.

    1984-01-01

    Among the topics discussed are the development history of planetary ring research, the view of planetary rings in astronomy and cosmology over the period 1600-1900, the characteristics of the ring systems of Saturn and Uranus, the ethereal rings of Jupiter and Saturn, dust-magnetosphere interactions, the effects of radiation forces on dust particles, the collisional interactions and physical nature of ring particles, transport effects due to particle erosion mechanisms, and collision-induced transport processes in planetary rings. Also discussed are planetary ring waves, ring particle dynamics in resonances, the dynamics of narrow rings, the origin and evolution of planetary rings, the solar nebula and planetary disk, future studies of the planetary rings by space probes, ground-based observatories and earth-orbiting satellites, and unsolved problems in planetary ring dynamics.

  13. Biomonitoring of environmental pollution using growth tree rings of Tipuana tipu: Quantification by synchrotron radiation total reflection X-ray fluorescence

    NASA Astrophysics Data System (ADS)

    Geraldo, S. M.; Canteras, F. B.; Moreira, S.

    2014-02-01

    Currently, many studies use the bioindicators to qualitatively and/or quantitatively measure pollution. The analyses of tree growth rings represent one such bioindicator as changes in the environment are often recorded as impressions in the wood. The main objective of the present study is to examine the growth rings of Tipuana tipu - a member of the Leguminosae family that is native to Argentina and Bolivia and was introduced in Brazil as an ornamental plant - for potentially toxic elements. T. tipu is one of the most common trees in the urban landscape of Sao Paulo city and would provide an accurate reflection of environment changes. Tree ring samples previously dated using Synchrotron Radiation Total Reflection X-ray Fluorescence were collected from strategic locations in Sao Paulo. These locations include Piracicaba (SP) that has little access and small flow traffic and the campus of the University of São Paulo. Some trace elements present concentrations higher than considered as normal in some periods. In São Paulo city, samples collected from the campus of University of São Paulo (Butantã), showed the highest toxicity, with concentrations above the tolerable limit for the elements: Cr, Cu, and Pb. For the samples collected in Piracicaba city, one sample presented highest concentrations for the majority of the elements when compared to the other four samples collected at the same place, exceeding the toxicity limits for: Cr, Ni, Cu, and Pb.

  14. Estimates of annual survival, growth, and recruitment of a white-tailed ptarmigan population in Colorado over 43 years

    USGS Publications Warehouse

    Wann, Greg; Aldridge, Cameron L.; Braun, Clait E.

    2014-01-01

    Long-term datasets for high-elevation species are rare, and considerable uncertainty exists in understanding how high-elevation populations have responded to recent climate warming. We present estimates of demographic vital rates from a 43-year population study of white-tailed ptarmigan (Lagopus leucura), a species endemic to alpine habitats in western North America. We used capture-recapture models to estimate annual rates of apparent survival, population growth, and recruitment for breeding-age ptarmigan, and we fit winter weather covariates to models in an attempt to explain annual variation. There were no trends in survival over the study period but there was strong support for age and sex effects. The average rate of annual growth suggests a relatively stable breeding-age population ( λ ¯ = 1.036), but there was considerable variation between years for both population growth and recruitment rates. Winter weather covariates only explained a small amount of variation in female survival and were not an important predictor of male survival. Cumulative winter precipitation was found to have a quadratic effect on female survival, with survival being highest during years of average precipitation. Cumulative winter precipitation was positively correlated with population growth and recruitment rates, although this covariate only explained a small amount of annual variation in these rates and there was considerable uncertainty among the models tested. Our results provide evidence for an alpine-endemic population that has not experienced extirpation or drastic declines. However, more information is needed to understand risks and vulnerabilities of warming effects on juveniles as our analysis was confined to determination of vital rates for breeding-age birds.

  15. The influence of summertime fog and overcast clouds on the growth of a coastal Californian pine: a tree-ring study.

    PubMed

    Williams, A Park; Still, Christopher J; Fischer, Douglas T; Leavitt, Steven W

    2008-06-01

    The coast of California is home to numerous rare, endemic conifers and other plants that are limited in distribution by drought sensitivity and the summer-dry climate that prevails across most of the state. Ecologists have long assumed that some coastal plant populations survived the early Pleistocene transition to a warmer and drier environment because they benefit from frequent fog and stratus clouds that provide water and shade during the rainless summer. One such population is that of Torrey pine (Pinus torreyana ssp. Insularis) on Santa Rosa Island in Channel Islands National Park. Here we report that the tree-ring width record from this population indicates strong growth sensitivities to summer fog drip and cloud shading. We quantified the effects of summer cloud cover by comparing ring-width indices to coastal airport cloud-frequency records (1944-2004). For the first time observed, summertime cloud frequency correlated positively with ring-width indices, regardless of whether the effect of rainfall was first removed from the ring-width record. The effect of ground-level fog was strongest in July early mornings (03:00 PST, R(2) = 0.262, P < 0.0002). The effect of clouds high enough to provide shade but not fog water was also strongest in July, but climbed steadily throughout the day before becoming strongest in late afternoon (16:00-18:00 PST, R(2) = 0.148, P < 0.004). Correlations were substantially stronger in years with higher soil moisture, suggesting that growth response to summer clouds is strongly affected by pre-summer rainfall. A change in the height and/or timing of coastal cloud formation with climate change would likely affect this and other populations of California's coastal vegetation. PMID:18368424

  16. The negative effect of biocrusts upon annual-plant growth on sand dunes during extreme droughts

    NASA Astrophysics Data System (ADS)

    Kidron, Giora J.

    2014-01-01

    The moisture content of crusted and non-crusted habitats on sand was measured.Higher available water characterized the non-crusted habitats during drought years.Non-crusted habitats had higher species diversity, density and biomass.Crusts exert a negative effect on annual plants during droughts.Mobile sand serve as fertility belts for annual plants during drought years.

  17. Discounting Report, 2012: Growth in Discounting Slows as Economy Improves. Ninth Annual Comparative Research Study

    ERIC Educational Resources Information Center

    Noel-Levitz, Inc, 2012

    2012-01-01

    This annual report summarizes the previous fall's outcomes and long-term trends for a sizable sample of private colleges and universities across the United States. The report is based on the annually aggregated freshman data of institutions that are currently partnering with Noel-Levitz to strategically manage more than $2 billion in institutional…

  18. Tree-ring based history of climate and disease in western Oregon forests

    EPA Science Inventory

    Annual tree-ring width data are often used to make inferences of past climate and the spatiotemporal climate-growth relationships. However, the climatic signal may be confounded with non-climatic signals such as disease or pest disturbances at unknown times in the past. Signal e...

  19. Saturn's rings

    NASA Technical Reports Server (NTRS)

    2000-01-01

    When seen from the unlit side, the rings of Saturn present a much different appearance from that familiar to telescopic observers. Relatively opaque areas like the B Ring turn black, while lightly populated zones, such as the C Ring and the Cassini Division, prove to excellent diffuse transmitters of sunlight. The A Ring, with intermediate opacity, is at an intermediate level of brightness.

  20. Time scaling of tree rings cell production in Siberia

    NASA Astrophysics Data System (ADS)

    Popkova, Margarita; Babushkina, Elena; Tychkov, Ivan; Shishov, Vladimir; Vaganov, Eugene

    2016-04-01

    It is assumed that an annual tree-ring growth is adequately determined by a linear function of local or regional precipitation and temperature with a set of coefficients that are temporally invariant. But often that relations are non-linear. The process-based tree-ring VS-model can be used to resolve the critical processes linking climate variables to tree-ring formation. This work describes a new block of VS-model which allows to estimate a cell production in tree rings and transfer it into time scale based on the simulated integral growth rates of the model. In the algorithm of time identification for cell production we used a integral growth rates simulated by the VS-model for each growing season. The obtained detailed approach with a calculation of the time of each cell formation improves significantly the date accuracy of new cell formation in growing season. As a result for each cell in the tree-ring we estimate the temporal moment of the cell production corresponded to the seasonal growth rate in the same time scale. The approach was applied and tested for the cell measurements obtained for Scots pine (Pinus sylvestris) for the period 1964-2013 in Malaya Minusa river (Khakassia, South Siberia). The work was supported by the Russian Science Foundation (RSF # 14-14-00219)

  1. Do tree ring chronologies have missing rings that distort volcanic cooling signal?: Tree ring records not distorted by missing rings

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-09-01

    Tree ring records are often used as a proxy for past climate. Trees form a new growth ring each year, and ring widths are related to temperature and other conditions at cold sites. Some recent studies have noted that tree ring width chronologies and resulting climate reconstructions do not appear to show the widespread cooling in the past millennium that would be expected following large volcanic eruptions. One hypothesis suggests that regional cooling after a volcanic eruption could be so severe that many trees do not form a ring at all, which leads researchers to misdate the tree ring chronology.

  2. [Annual variation of different phosphorus forms and response of algae growth in Meiliang bay of Taihu Lake].

    PubMed

    Wang, Ming; Wu, Xiao-fei; Li, Da-peng; Li, Xiang; Huang, Yong

    2015-01-01

    Based on the monthly investigations of different forms of phosphorus(P) and algae growth from January to December 2013 in Meiliang bay of Taihu Lake, the transformation of different P forms and the relationship between different P forms and algae growth was investigated under the dual conditions of disturbance due to wind and wave and algae growth. Results of the total P(TP), particulate P (PP), dissolved total P(DTP), dissolved inorganic P(DIP) and bioavailable P(BAP) showed that the monthly concentrations reached the maximum in summer and autumn while the minimum in winter and spring. In addition, the algae growth showed the same trends as above. However, no variation was found in the dissolved organic P(DOP) and bioavailable particulate P(BAPP). The bioavailability of PP was only 12.75% from June to October, which was obviously lower than the annual mean (37.14%). It was attributed to the acceleration on the transformation of PP to DTP due to the immobilization of sedimentary P under sediment disturbance and algae adsorption. The percentage of DTP in BAP was up to 69.33% (average), which was obviously higher than the percentage of bioavailable PP (30.66%, average) and the annual mean (56.63%) of DTP during the interval. In addition, the algae bloom appeared in the interval. PMID:25898650

  3. Inter-annual changes in detritus-based food chains can enhance plant growth response to elevated atmospheric CO2.

    PubMed

    Hines, Jes; Eisenhauer, Nico; Drake, Bert G

    2015-12-01

    Elevated atmospheric CO2 generally enhances plant growth, but the magnitude of the effects depend, in part, on nutrient availability and plant photosynthetic pathway. Due to their pivotal role in nutrient cycling, changes in abundance of detritivores could influence the effects of elevated atmospheric CO2 on essential ecosystem processes, such as decomposition and primary production. We conducted a field survey and a microcosm experiment to test the influence of changes in detritus-based food chains on litter mass loss and plant growth response to elevated atmospheric CO2 using two wetland plants: a C3 sedge (Scirpus olneyi) and a C4 grass (Spartina patens). Our field study revealed that organism's sensitivity to climate increased with trophic level resulting in strong inter-annual variation in detritus-based food chain length. Our microcosm experiment demonstrated that increased detritivore abundance could not only enhance decomposition rates, but also enhance plant growth of S. olneyi in elevated atmospheric CO2 conditions. In contrast, we found no evidence that changes in the detritus-based food chains influenced the growth of S. patens. Considered together, these results emphasize the importance of approaches that unite traditionally subdivided food web compartments and plant physiological processes to understand inter-annual variation in plant production response to elevated atmospheric CO2. PMID:25953075

  4. Ecotypic variation in growth responses to simulated herbivory: trade-off between maximum relative growth rate and tolerance to defoliation in an annual plant

    PubMed Central

    Camargo, Iván D.; Tapia-López, Rosalinda; Núñez-Farfán, Juan

    2015-01-01

    It has been hypothesized that slow-growing plants are more likely to maximize above-ground biomass and fitness when defoliated by herbivores than those with an already high relative growth rate (RGR). Some populations of the annual herb Datura stramonium L. can tolerate foliar damage better than others. The physiological basis of this difference is examined here in a comparative study of two ecotypes that differ in tolerance and maximum growth rate, using a growth analytical approach. One hundred and fifty-four plants of each ecotype grown under controlled conditions were suddenly defoliated (35 % of total leaf area removed) and a similar sample size of plants remained undefoliated (control). Ontogenetic plastic changes in RGR and its growth components [net assimilation rate (NAR), specific leaf area and leaf weight ratio (LWR)] after defoliation were measured to determine whether these plastic changes maximize plant growth and fitness. Different ontogenetic phases of the response were discerned and increased RGR of defoliated plants was detected at the end of the experimental period, but brought about by a different growth component (NAR or LWR) in each ecotype. These changes in RGR are putatively related to increases in fitness in defoliated environments. At the intra-specific scale, data showed a trade-off between the ability to grow under benign environmental conditions and the ability to tolerate resource limitation due to defoliation. PMID:25725085

  5. Annual Enrollment Report: Growth in Number of Students Studying Journalism and Mass Communication Slows.

    ERIC Educational Resources Information Center

    Becker, Lee B.; Vlad, Tudor; Huh, Jisu; Daniels, George L.

    2002-01-01

    Provides the key findings of the 2001 Annual Survey of Journalism and Mass Communication Enrollments. Shows that undergraduate enrollments continued to grow while graduate enrollments declined. Discusses degrees granted and race, ethnicity, and gender factors. (PM)

  6. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  7. Facile solvothermal synthesis of abnormal growth of one-dimensional ZnO nanostructures by ring-opening reaction of polyvinylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Xu, G.; Wang, X. L.; Liu, G. Z.

    2015-02-01

    Abnormal growth of one-dimensional (1-D) ZnO nanostructures (NSs) have been accomplished with the assistance of polyvinylpyrrolidone (PVP) under a super high alkaline alcoholic solvothermal condition. The products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The effect of synthetic conditions, such as reaction temperature and the addition of PVP, on the morphologies of ZnO products were investigated. The results show that PVP molecules had the significant role in the transformation of morphologies of ZnO NSs ranging from nanorods, nanoparticles to pyramids, as well as flower-like assembly features. The possible growth mechanism of ZnO pyramids was proposed based on ring-opening reaction of PVP.

  8. Arctic tree rings as recorders of variations in light availability

    PubMed Central

    Stine, A. R.; Huybers, P.

    2014-01-01

    Annual growth ring variations in Arctic trees are often used to reconstruct surface temperature. In general, however, the growth of Arctic vegetation is limited both by temperature and light availability, suggesting that variations in atmospheric transmissivity may also influence tree-ring characteristics. Here we show that Arctic tree-ring density is sensitive to changes in light availability across two distinct phenomena: explosive volcanic eruptions (P<0.01) and the recent epoch of global dimming (P<0.01). In each case, the greatest response is found in the most light-limited regions of the Arctic. Essentially no late 20th century decline in tree-ring density relative to temperature is seen in the least light-limited regions of the Arctic. Consistent results follow from analysis of tree-ring width and from individually analysing each of seven tree species. Light availability thus appears an important control, opening the possibility for using tree rings to reconstruct historical changes in surface light intensity. PMID:24805143

  9. Vascular ring

    MedlinePlus

    ... with aberrant subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... accounts for less than 1% of all congenital heart problems. The condition occurs as often in males ...

  10. Neptune's rings

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

  11. Intra-annual variability of anatomical structure and δ13C values within tree rings of spruce and pine in alpine, temperate and boreal Europe

    PubMed Central

    Vaganov, Eugene A.; Skomarkova, Marina V.; Knohl, Alexander; Brand, Willi A.; Roscher, Christiane

    2009-01-01

    Tree-ring width, wood density, anatomical structure and 13C/12C ratios expressed as δ13C-values of whole wood of Picea abies were investigated for trees growing in closed canopy forest stands. Samples were collected from the alpine Renon site in North Italy, the lowland Hainich site in Central Germany and the boreal Flakaliden site in North Sweden. In addition, Pinus cembra was studied at the alpine site and Pinus sylvestris at the boreal site. The density profiles of tree rings were measured using the DENDRO-2003 densitometer, δ13C was measured using high-resolution laser-ablation-combustion-gas chromatography-infra-red mass spectrometry and anatomical characteristics of tree rings (tracheid diameter, cell-wall thickness, cell-wall area and cell-lumen area) were measured using an image analyzer. Based on long-term statistics, climatic variables, such as temperature, precipitation, solar radiation and vapor pressure deficit, explained <20% of the variation in tree-ring width and wood density over consecutive years, while 29–58% of the variation in tree-ring width were explained by autocorrelation between tree rings. An intensive study of tree rings between 1999 and 2003 revealed that tree ring width and δ13C-values of whole wood were significantly correlated with length of the growing season, net radiation and vapor pressure deficit. The δ13C-values were not correlated with precipitation or temperature. A highly significant correlation was also found between δ13C of the early wood of one year and the late wood of the previous year, indicating a carry-over effect of the growing conditions of the previous season on current wood production. This latter effect may explain the high autocorrelation of long-term tree-ring statistics. The pattern, however, was complex, showing stepwise decreases as well as stepwise increases in the δ13C between late wood and early wood. The results are interpreted in the context of the biochemistry of wood formation and its linkage

  12. Ring-opening copolymerization of maleic anhydride with epoxides: a chain-growth approach to unsaturated polyesters.

    PubMed

    DiCiccio, Angela M; Coates, Geoffrey W

    2011-07-20

    We report the ring-opening copolymerization of maleic anhydride with a variety of epoxides catalyzed by a chromium(III) salen complex. Quantitative isomerization of the cis-maleate form of all polymers affords the trans-fumarate analogues. Addition of chain transfer reagents yields low M(n), narrow PDI polymer samples. This method provides access to a range of new unsaturated polyesters with versatile functionality, as well as the first synthesis of high molecular weight poly(propylene fumarate). PMID:21699247

  13. Soil bulk density and strength effects on seedling growth in annual ryegrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    No-till seeding is commonly found to delay establishment and inhibit early growth of forage grasses, compared with sowing after tillage. Among several possible causes of retarded growth following no-till planting of forage species, the effects of soil compaction have received little attention. Studi...

  14. Growth Regulator Herbicides Prevent Invasive Annual grass Seed Production Under Field Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growth regulator herbicides, such as 2,4-D, dicamba, picloram, and aminopyralid, are commonly used to control broadleaf weeds in grasslands, non-croplands and cereal crops (e.g. wheat, barley). If applied to cereals at late growth stages, while the grasses are developing reproductive parts, the her...

  15. Planetary Rings

    NASA Astrophysics Data System (ADS)

    Gordon, M. K.; Araki, S.; Black, G. J.; Bosh, A. S.; Brahic, A.; Brooks, S. M.; Charnoz, S.; Colwell, J. E.; Cuzzi, J. N.; Dones, L.; Durisen, R. H.; Esposito, L. W.; Ferrari, C.; Festou, M.; French, R. G.; Giuliatti-Winter, S. M.; Graps, A. L.; Hamilton, D. P.; Horanyi, M.; Karjalainen, R. M.; Krivov, A. V.; Krueger, H.; Larson, S. M.; Levison, H. F.; Lewis, M. C.; Lissauer, J. J.; Murray, C. D.; Namouni, F.; Nicholson, P. D.; Olkin, C. B.; Poulet, F.; Rappaport, N. J.; Salo, H. J.; Schmidt, J.; Showalter, M. R.; Spahn, F.; Spilker, L. J.; Srama, R.; Stewart, G. R.; Yanamandra-Fisher, P.

    2002-08-01

    The past two decades have witnessed dramatic changes in our view and understanding of planetary rings. We now know that each of the giant planets in the Solar System possesses a complex and unique ring system. Recent studies have identified complex gravitational interactions between the rings and their retinues of attendant satellites. Among the four known ring systems, we see elegant examples of Lindblad and corotation resonances (first invoked in the context of galactic disks), electromagnetic resonances, spiral density waves and bending waves, narrow ringlets which exhibit internal modes due to collective instabilities, sharp-edged gaps maintained via tidal torques from embedded moonlets, and tenuous dust belts created by meteoroid impact onto, or collisions between, parent bodies. Yet, as far as we have come, our understanding is far from complete. The fundamental questions confronting ring scientists at the beginning of the twenty-first century are those regarding the origin, age and evolution of the various ring systems, in the broadest context. Understanding the origin and age requires us to know the current ring properties, and to understand the dominant evolutionary processes and how they influence ring properties. Here we discuss a prioritized list of the key questions, the answers to which would provide the greatest improvement in our understanding of planetary rings. We then outline the initiatives, missions, and other supporting activities needed to address those questions, and recommend priorities for the coming decade in planetary ring science.

  16. The dynamic of annual carbon allocation to wood in European forests is consistent with a combined source-sink limitation of growth: implications for modelling

    NASA Astrophysics Data System (ADS)

    Guillemot, J.; Martin-StPaul, N. K.; Dufrêne, E.; François, C.; Soudani, K.; Ourcival, J. M.; Delpierre, N.

    2015-02-01

    The extent to which forest growth is limited by carbon (C) supply (source control) or by cambial activity (sink control) will condition the response of trees to global changes. However, the physiological processes responsible for the limitation of forest growth are still under debate. The aim of this study is to evaluate the key drivers of the annual carbon allocation to wood along large soil and climate regional gradients in five tree species representative of the main European forest biomes (Fagus sylvatica, Quercus petraea, Quercus ilex, Quercus robur and Picea abies). Combining field measurements and process-based simulations at 49 sites (931 site-years), we assessed the stand biomass growth dependences at both inter-site and inter-annual scales. Specifically, the relative influence of forest C balance (source control), direct environmental control (water and temperature controls of sink activity) and allocation adjustments related to age, past climate conditions, competition intensity and soil nutrient availability on growth were quantified. The inter-site variability in stand C allocation to wood was predominantly driven by an age-related decline. The direct control of temperature or water stress on sink activity (i.e. independently from their effects on C supply) exerted a strong influence on the annual stand woody growth in all the species considered, including deciduous temperate species. The lagged effect of the past environment conditions was a significant driver of the annual C allocation to wood. Carbon supply appeared to strongly limit growth only in deciduous temperate species. We provide an evaluation of the spatio-temporal dynamics of annual carbon allocation to wood in European forests. Our study supports the premise that European forest growth is under a complex control including both source and sink limitations. The relative influences of the different growth drivers strongly vary across years and spatial ecological gradients. We suggest a

  17. Field growth comparisons of invasive alien annual and native perennial grasses in monocultures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Medusahead is rapidly invading native grassland and cheatgrass dominated grassland throughout the western US. Understanding growth dynamics of medusahead relative to bluebunch wheatgrass and cheatgrass is central to predicting and managing medusahead invasion. We hypothesized that medusahead would...

  18. [Plant growth with limited water]. [Annual report, December 15, 1992--December 14, 1993

    SciTech Connect

    Not Available

    1993-12-01

    We used a soybean seedling system to explore the mechanism of growth limitation by water deficiency (low {Psi}{sub W}). Our prior work had show that (low {Psi}{sub W} inhibited plant growth initially because of a physical limitation to water uptake that appeared to result from a decrease in the {Psi}{sub W} gradient feeding water to the enlarging cells. The gradient was shown to originate from cell wall yielding and was altered primarily at the vascular tissue. In the present grant, we reported the detailed shape of the gradient. We also found that growth could mobilize water from mature tissues in the complete absence of external water using the gradient in {Psi}{sub W}. Growth was maintained by this mobilization. After growth has been inhibited a few hours, metabolic changes occur and a 28kD protein accumulates in the wall fraction of the growth-affected cells. In the present grant, we showed that the mRNA for the protein accumulated in a tissue-specific manner similar to that of the protein, and the accumulation was correlated with the growth response. Other investigators working independently with an acid phosphatase found a deduced amino acid sequence similar to that for the 28kD protein we had published. Biochemical tests showed that the 28kD protein and a related 3lkD protein expressed acid phosphatase activity. We found that the acid phosphatase Of the 28kD protein was in the cell walls of intact plants (in addition to being in the cytoplasm). Current work focuses on the role of this protein. Efforts were made to reverse the growth inhibition at low {Phi}{sub W} by treating growing tissues with low pH buffer, but the protons apparently failed to penetrate the cuticle.

  19. Directed Growth of Polymer Nanorods Using Surface-Initiated Ring-Opening Polymerization of N-Allyl N-Carboxyanhydride.

    PubMed

    Lu, Lu; Lahasky, Samuel H; Zhang, Donghui; Garno, Jayne C

    2016-02-17

    A stepwise chemistry route was used to prepare arrays of polymer nanostructures of poly(N-allyl glycine) on Si(111) using particle lithography. The nanostructures were used for studying surface reactions with advanced measurements of atomic force microscopy (AFM). In the first step to fabricate the surface platform, isolated nanopores were prepared within a thin film of octadecyltrichlorosilane (OTS). The OTS served as a surface resist, and the areas of nanopores provided multiple, regularly shaped sites for further reaction. An initiator, (3-aminopropyl)triethoxysilane (APTES), was grown selectively inside the nanopores to define sites for polymerization. The initiator attached selectively to the sites of nanopores indicating OTS prevented nonspecific adsorption. Surface-initiated ring-opening polymerization of N-allyl N-carboxyanhydride with APTES produced polymer nanorods on the nanodots of APTES presenting amine functional groups. The surface changes for each step were monitored using high resolution atomic force microscopy (AFM). Slight variations in the height of the poly(N-allyl glycine) nanorods were observed which scale correspondingly to the initial dimensions of nanopores. The distance between adjacent polymer nanorods was controlled by the size of mesoparticle masks used in the experiment. This surface platform has potential application in biotechnology for smart coatings or biosensors. PMID:26789943

  20. Spark ignited turbulent flame kernel growth. Annual report, January--December, 1992

    SciTech Connect

    Santavicca, D.A.

    1994-06-01

    Cyclic combustion variations in spark-ignition engines limit the use of dilute charge strategies for achieving low NO{sub x} emissions and improved fuel economy. Results from an experimental study of the effect of incomplete fuel-air mixing (ifam) on spark-ignited flame kernel growth in turbulent propane-air mixtures are presented. The experiments were conducted in a turbulent flow system that allows for independent variation of flow parameters, ignition system parameters, and the degree of fuel-air mixing. Measurements were made at 1 atm and 300 K conditions. Five cases were studied; a premixed and four incompletely mixed cases with 6%, 13%, 24% and 33% RMS (root-mean-square) fluctuations in the fuel/air equivalence ratio. High speed laser shadowgraphy at 4,000 frames-per-second was used to record flame kernel growth following spark ignition, from which the equivalent flame kernel radius as a function of time was determined. The effect of ifam was evaluated in terms of the flame kernel growth rate, cyclic variations in the flame kernel growth, and the rate of misfire. The results show that fluctuations in local mixture strength due to ifam cause the flame kernel surface to become wrinkled and distorted; and that the amount of wrinkling increases as the degree of ifam. Ifam was also found to result in a significant increase in cyclic variations in the flame kernel growth. The average flame kernel growth rates for the premixed and the incompletely mixed cases were found to be within the experimental uncertainty except for the 33%-RMS-fluctuation case where the growth rate is significantly lower. The premixed and 6%-RMS-fluctuation cases had a 0% misfire rate. The misfire rates were 1% and 2% for the 13%-RMS-fluctuation and 24%-RMS-fluctuation cases, respectively; however, it drastically increased to 23% in the 33%-RMS-fluctuation case.

  1. Effect of D2O on growth properties and chemical structure of annual ryegrass (Lolium multiflorum)

    SciTech Connect

    Evans, Barbara R; Bali, Garima; Reeves, David T; O'Neill, Hugh Michael; Sun, Qining; Shah, Riddhi S; Ragauskas, Arthur

    2014-01-01

    In present paper, we report the production and detailed structural analysis of deuterium-enriched rye grass (Lolium multiflorum) for neutron scattering experiments. An efficient method to produce deuterated biomass was developed by designing hydroponic perfusion chambers. In preliminary studies, the partial deuterated rye samples were grown in increasing levels of D2O to study the seed germination and the level of deuterium incorporation as a function of D2O concentration. Solution NMR method indicated 36.9 % deuterium incorporation in 50 % D2O grown annual rye samples and further significant increase in the deuterium incorporation level was observed by germinating the rye seedlings in H2O and growing in 50 % D2O inside the perfusion chambers. Moreover, in an effort to compare the substrate characteristics related to enzymatic hydrolysis on deuterated and protiated version of biomass, annual rye grown in 50 % D2O was selected for detailed biomass characterization studies. The compositional analyses, degree of polymerization and cellulose crystallinity were compared with its protiated control. The cellulose molecular weight indicated slight variation with deuteration; however, hemicellulose molecular weights and cellulose crystallinity remain unaffected with the deuteration. Besides the minor differences in biomass components, the development of deuterated biomass for neutron scattering application is essential to understand the complex biomass conversion processes.

  2. Positive Effects of Non-Native Grasses on the Growth of a Native Annual in a Southern California Ecosystem

    PubMed Central

    Pec, Gregory J.; Carlton, Gary C.

    2014-01-01

    Fire disturbance is considered a major factor in the promotion of non-native plant species. Non-native grasses are adapted to fire and can alter environmental conditions and reduce resource availability in native coastal sage scrub and chaparral communities of southern California. In these communities persistence of non-native grasses following fire can inhibit establishment and growth of woody species. This may allow certain native herbaceous species to colonize and persist beneath gaps in the canopy. A field manipulative experiment with control, litter, and bare ground treatments was used to examine the impact of non-native grasses on growth and establishment of a native herbaceous species, Cryptantha muricata. C. muricata seedling survival, growth, and reproduction were greatest in the control treatment where non-native grasses were present. C. muricata plants growing in the presence of non-native grasses produced more than twice the number of flowers and more than twice the reproductive biomass of plants growing in the treatments where non-native grasses were removed. Total biomass and number of fruits were also greater in the plants growing in the presence of non-native grasses. Total biomass and reproductive biomass was also greater in late germinants than early germinants growing in the presence of non-native grasses. This study suggests a potential positive effect of non-native grasses on the performance of a particular native annual in a southern California ecosystem. PMID:25379790

  3. Millennium-Scale Crossdating and Inter-Annual Climate Sensitivities of Standing California Redwoods

    PubMed Central

    Carroll, Allyson L.; Sillett, Stephen C.; Kramer, Russell D.

    2014-01-01

    Extremely decay-resistant wood and fire-resistant bark allow California’s redwoods to accumulate millennia of annual growth rings that can be useful in biological research. Whereas tree rings of Sequoiadendron giganteum (SEGI) helped formalize the study of dendrochronology and the principle of crossdating, those of Sequoia sempervirens (SESE) have proven much more difficult to decipher, greatly limiting dendroclimatic and other investigations of this species. We overcame these problems by climbing standing trees and coring trunks at multiple heights in 14 old-growth forest locations across California. Overall, we sampled 1,466 series with 483,712 annual rings from 120 trees and were able to crossdate 83% of SESE compared to 99% of SEGI rings. Standard and residual tree-ring chronologies spanning up to 1,685 years for SESE and 1,538 years for SEGI were created for each location to evaluate crossdating and to examine correlations between annual growth and climate. We used monthly values of temperature, precipitation, and drought severity as well as summer cloudiness to quantify potential drivers of inter-annual growth variation over century-long time series at each location. SESE chronologies exhibited a latitudinal gradient of climate sensitivities, contrasting cooler northern rainforests and warmer, drier southern forests. Radial growth increased with decreasing summer cloudiness in northern rainforests and a central SESE location. The strongest dendroclimatic relationship occurred in our southernmost SESE location, where radial growth correlated negatively with dry summer conditions and exhibited responses to historic fires. SEGI chronologies showed negative correlations with June temperature and positive correlations with previous October precipitation. More work is needed to understand quantitative relationships between SEGI radial growth and moisture availability, particularly snowmelt. Tree-ring chronologies developed here for both redwood species have

  4. Millennium-scale crossdating and inter-annual climate sensitivities of standing California redwoods.

    PubMed

    Carroll, Allyson L; Sillett, Stephen C; Kramer, Russell D

    2014-01-01

    Extremely decay-resistant wood and fire-resistant bark allow California's redwoods to accumulate millennia of annual growth rings that can be useful in biological research. Whereas tree rings of Sequoiadendron giganteum (SEGI) helped formalize the study of dendrochronology and the principle of crossdating, those of Sequoia sempervirens (SESE) have proven much more difficult to decipher, greatly limiting dendroclimatic and other investigations of this species. We overcame these problems by climbing standing trees and coring trunks at multiple heights in 14 old-growth forest locations across California. Overall, we sampled 1,466 series with 483,712 annual rings from 120 trees and were able to crossdate 83% of SESE compared to 99% of SEGI rings. Standard and residual tree-ring chronologies spanning up to 1,685 years for SESE and 1,538 years for SEGI were created for each location to evaluate crossdating and to examine correlations between annual growth and climate. We used monthly values of temperature, precipitation, and drought severity as well as summer cloudiness to quantify potential drivers of inter-annual growth variation over century-long time series at each location. SESE chronologies exhibited a latitudinal gradient of climate sensitivities, contrasting cooler northern rainforests and warmer, drier southern forests. Radial growth increased with decreasing summer cloudiness in northern rainforests and a central SESE location. The strongest dendroclimatic relationship occurred in our southernmost SESE location, where radial growth correlated negatively with dry summer conditions and exhibited responses to historic fires. SEGI chronologies showed negative correlations with June temperature and positive correlations with previous October precipitation. More work is needed to understand quantitative relationships between SEGI radial growth and moisture availability, particularly snowmelt. Tree-ring chronologies developed here for both redwood species have

  5. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  6. The Impact of Non-Passive Monitor Behavior on Developing Tree Ring Elemental Concentration Based Chronologies of Environmental Change

    NASA Astrophysics Data System (ADS)

    Bukata, A. R.; Kyser, K.

    2008-12-01

    Most temperate tree species contain visibly distinct annual growth rings. These individual rings contain distinct isotopic and elemental compositions from pith to bark. As these individual rings can be dated to specific growth years, it is tempting to interpret these variations as directly reflecting temporal changes in the geochemical environment. However, tree physiology, in addition to changes in elemental bioavailability can effect the elemental composition of the growth ring. The viability of variations in tree ring elemental concentration as a proxy for changing environmental conditions is dependent on whether they are passive monitors of element bioavailability or their active incorporation can be characterized and properly considered during interpretation. We measured elemental concentrations in tree rings from red and white oak trees at sites across Southern Ontario, Canada, to determine whether they passively record changes in geochemical cycling in the presence of environmental stress. Periods of stress were defined as sustained intervals with elevated δ13C values in tree rings relative to contemporaneous atmospheric carbon dioxide. In some trees, nutrient concentrations (Ca, Mg, Mn) were highly variable during periods of stress while chemically similar non-nutrients (Ba, Sr) and the anthropogenic pollutant Pb were not. The concentration of Ca and Sr in the tree rings were related to bedrock type and leachable concentration in the soil, while Mn, Ba and Pb were not, but were inversely related to soil pH. The erratic behavior of nutrients during periods of stress suggests that although they are not always passive monitors of bioavailability, their variation may have environmental significance. The application of analytical techniques such as laser ablation ICP-MS to micro- sample across individual rings and around the bole will likely lead to the application of dendrochemistry to study environmental questions of a spatial or sub-annual nature. Although

  7. Selections from the ABC 2014 Annual Conference, Philadelphia, Pennsylvania: Let Favorite Assignments Ring: Sharpening Communication Tools and Self and Career Development

    ERIC Educational Resources Information Center

    Whalen, D. Joel; Crenshaw, Cheri; Ortiz, Lorelei A.; Vik, Gretchen N.; Meredith, Michael J.; Deambrosi, Alfredo; Luck, Susan L.; Rausch, Georgi; Canas, Kathryn; Hicks, Nancy; Newman, Amy; Hofacker, Cynthia M.; Webb, Susan Hall; Zizik, Catherine H.

    2015-01-01

    This article, the first of a two-part series, catalogs teaching innovations from the 2014 Association for Business Communication Annual Conference. These 12 assignments debuted during two "My Favorite Assignment" sessions. Learning experiences included job-seeking skills--résumé writing, writing job applications, sharpening interview…

  8. Employer Child Care Continues Slow, but Steady Growth: Fifteenth Annual Status Report on Employer Child Care

    ERIC Educational Resources Information Center

    Neugebauer, Roger

    2006-01-01

    In the 1990s, employer child care operated by management organizations was consistently increasing at a rate of over 10% per year. However, since 2001, the growth rate has remained in the 4-6% range. In this article, the author presents differing views on the current trends and future prospects on employer child care. Ty Durekas, from Children's…

  9. Benchmarks for Expected Annual Academic Growth for Students in the Bottom Quartile of the Normative Distribution

    ERIC Educational Resources Information Center

    Scammacca, Nancy K.; Fall, Anna-Mária; Roberts, Greg

    2015-01-01

    Effect sizes are commonly reported for the results of educational interventions. However, researchers struggle with interpreting their magnitude in a way that transcends generic guidelines. Effect sizes can be interpreted in a meaningful context by benchmarking them against typical growth for students in the normative distribution. Such benchmarks…

  10. Small Variance in Growth Rate in Annual Plants has Large Effects on Genetic Drift

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When plant size is strongly correlated with plant reproduction, variance in growth rates results in a lognormal distribution of seed production within a population. Fecundity variance affects effective population size (Ne), which reflects the ability of a population to maintain beneficial mutations ...

  11. Arabidopsis RING E3 ubiquitin ligase AtATL80 is negatively involved in phosphate mobilization and cold stress response in sufficient phosphate growth conditions.

    PubMed

    Suh, Ji Yeon; Kim, Woo Taek

    2015-08-01

    Phosphate (Pi) remobilization in plants is critical to continuous growth and development. AtATL80 is a plasma membrane (PM)-localized RING E3 ubiquitin (Ub) ligase that belongs to the Arabidopsis Tóxicos en Levadura (ATL) family. AtATL80 was upregulated by long-term low Pi (0-0.02 mM KH2PO4) conditions in Arabidopsis seedlings. AtATL80-overexpressing transgenic Arabidopsis plants (35S:AtATL80-sGFP) displayed increased phosphorus (P) accumulation in the shoots and lower biomass, as well as reduced P-utilization efficiency (PUE) under high Pi (1 mM KH2PO4) conditions compared to wild-type plants. The loss-of-function atatl80 mutant line exhibited opposite phenotypic traits. The atatl80 mutant line bolted earlier than wild-type plants, whereas AtATL80-overexpressors bloomed significantly later and produced lower seed yields than wild-type plants under high Pi conditions. Thus, AtATL80 is negatively correlated not only with P content and PUE, but also with biomass and seed yield in Arabidopsis. In addition, AtATL80-overexpressors were significantly more sensitive to cold stress than wild-type plants, while the atatl80 mutant line exhibited an increased tolerance to cold stress. Taken together, our results suggest that AtATL80, a PM-localized ATL-type RING E3 Ub ligase, participates in the Pi mobilization and cold stress response as a negative factor in Arabidopsis. PMID:26086094

  12. [Growth modeling of Albizia niopoides (Mimosaceae) using dendrochronological methods].

    PubMed

    Giraldo, Víctor David; del Valle, Jorge Ignacio

    2012-09-01

    The annual growth rings in tropical trees are fairly common, but their study is relatively recent. Growth rings were found in trees of Albizia niopoides from the Porce River Canyon, Central Cordillera of the Colombian Andes. A total of 33 cross-sections were collected from trees distributed throughout the study area from 664-870masl. Cross-dating, spaguetti plot and 14C analyses were used to demonstrate ring annuality, assuming as hypothesis that these are real annual growth rings. A combination of descriptive analysis of time series (smoothing and pre-whitening) to filter climate noise and nonlinear regression with weighted residuals was used to fit the diameter to Korfs growth model, in which the coefficient of determination reaches values close to 100%. The positive residual autocorrelation of order 1, although not significant, is explained by the existence of energy reserves in the stem and by the accumulation of diameter increments required for the construction of the diameter growth model. The current and mean annual maximum increment rates are 1.03 and 0.94cm/year at ages 18 and 46 years old, respectively. These trees are classified within the group of fast growing species which can reach a cut diameter of over 50cm in approximately 52 years. PMID:23025084

  13. Extreme Drought Events Revealed in Amazon Tree Ring Records

    NASA Astrophysics Data System (ADS)

    Jenkins, H. S.; Baker, P. A.; Guilderson, T. P.

    2010-12-01

    The Amazon basin is a center of deep atmospheric convection and thus acts as a major engine for global hydrologic circulation. Yet despite its significance, a full understanding of Amazon rainfall variability remains elusive due to a poor historical record of climate. Temperate tree rings have been used extensively to reconstruct climate over the last thousand years, however less attention has been given to the application of dendrochronology in tropical regions, in large part due to a lower frequency of tree species known to produce annual rings. Here we present a tree ring record of drought extremes from the Madre de Dios region of southeastern Peru over the last 190 years. We confirm that tree ring growth in species Cedrela odorata is annual and show it to be well correlated with wet season precipitation. This correlation is used to identify extreme dry (and wet) events that have occurred in the past. We focus on drought events identified in the record as drought frequency is expected to increase over the Amazon in a warming climate. The Cedrela chronology records historic Amazon droughts of the 20th century previously identified in the literature and extends the record of drought for this region to the year 1816. Our analysis shows that there has been an increase in the frequency of extreme drought (mean recurrence interval = 5-6 years) since the turn of the 20th century and both Atlantic and Pacific sea surface temperature (SST) forcing mechanisms are implicated.

  14. Relating annual increments of the endangered Blanding's turtle plastron growth to climate.

    PubMed

    Richard, Monik G; Laroque, Colin P; Herman, Thomas B

    2014-05-01

    This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration. PMID:24963390

  15. Relating annual increments of the endangered Blanding's turtle plastron growth to climate

    PubMed Central

    Richard, Monik G; Laroque, Colin P; Herman, Thomas B

    2014-01-01

    This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration. PMID:24963390

  16. Effects of salinity on the growth, physiology and relevant gene expression of an annual halophyte grown from heteromorphic seeds

    PubMed Central

    Cao, Jing; Lv, Xiu Yun; Chen, Ling; Xing, Jia Jia; Lan, Hai Yan

    2015-01-01

    Seed heteromorphism provides plants with alternative strategies for survival in unfavourable environments. However, the response of descendants from heteromorphic seeds to stress has not been well documented. Suaeda aralocaspica is a typical annual halophyte, which produces heteromorphic seeds with disparate forms and different germination characteristics. To gain an understanding of the salt tolerance of descendants and the impact of seed heteromorphism on progeny of this species, we performed a series of experiments to investigate the plant growth and physiological parameters (e.g. osmolytes, oxidative/antioxidative agents and enzymes), as well as expression patterns of corresponding genes. Results showed that osmolytes (proline and glycinebetaine) were significantly increased and that excess reactive oxygen species (O2−, H2O2) produced under high salinity were scavenged by increased levels of antioxidant enzymes (superoxide dismutase, ascorbate peroxidase and glutathione reductase) and corresponding antioxidants (ascorbic acid and glutathione). Moreover, enhancement of phosphoenolpyruvate carboxylase activity at high salt intensity had a positive effect on photosynthesis. The descendants from heteromorphic seeds presented no significant difference in performance with or without salinity. In conclusion, we found that high salinity induced the same active physiological responses in plants from heteromorphic seeds of S. aralocaspica, there was no carry-over of seed heteromorphism to plants: all the descendants required salinity for optimal growth and adaptation to their natural habitat. PMID:26386128

  17. Wall proficient E. coli capable of sustained growth in the absence of the Z-ring division machine.

    PubMed

    Mercier, Romain; Kawai, Yoshikazu; Errington, Jeff

    2016-01-01

    The peptidoglycan cell wall is a major protective external sheath in bacteria and a key target for antibiotics(1). Peptidoglycan is present in virtually all bacteria, suggesting that it was probably present in the last bacterial common ancestor(2). Cell wall expansion is orchestrated by cytoskeletal proteins related to actin (MreB) and tubulin (FtsZ)(3). FtsZ is a key essential player in a highly organized division machine that directs an invaginating annulus of cell wall peptidoglycan. The recent discovery that cell-wall-less bacteria (L-forms) can grow and divide independently of FtsZ(4,5), provided a means of generating an ftsZ null mutant of Escherichia coli. Remarkably, we have been able to isolate variants of E. coli that lack FtsZ but are capable of efficient growth in a walled state. Genetic analysis reveals that a combination of mutations is needed for this phenotype. Importantly, the suppressive mutations lead to a major cell shape change, from the normal cylindrical shape to a branched and bulging, ramified shape, which we call 'coli-flower'. The results highlight the versatility of bacterial cells and illustrate possible evolutionary routes leading to the emergence of specialized bacteria, such as pathogenic Chlamydia or aquatic Planctomycetes, that lack FtsZ but retain the cell wall(6-8). PMID:27573111

  18. DOE/BES/NSET annual report on growth of metal and semiconductor nanostructures using localized photocatalysts.

    SciTech Connect

    Haddad, Raid Edward; Brinker, C. Jeffrey; Shelnutt, John Allen; Yang, Yi; Nuttall, H. Eric; Watt, Richard K.; Singl, Anup K.; Challa, Sivakumar R.; Wang, Zhongchun; van Swol, Frank B.; Pereira, Eulalia; Qiu, Yan; Jiang, Ying-Bing; Xu, Huifang; Medforth, Craig J.; Song, Yujiang

    2003-10-01

    Our overall goal is to understand and develop a novel light-driven approach to the controlled growth of unique metal and semiconductor nanostructures and nanomaterials. In this photochemical process, bio-inspired porphyrin-based photocatalysts reduce metal salts in aqueous solutions at ambient temperatures to provide metal nucleation and growth centers. Photocatalyst molecules are pre-positioned at the nanoscale to control the location and morphology of the metal nanostructures grown. Self-assembly, chemical confinement, and molecular templating are some of the methods used for nanoscale positioning of the photocatalyst molecules. When exposed to light, the photocatalyst molecule repeatedly reduces metal ions from solution, leading to deposition and the synthesis of the new nanostructures and nanostructured materials. Studies of the photocatalytic growth process and the resulting nanostructures address a number of fundamental biological, chemical, and environmental issues and draw on the combined nanoscience characterization and multi-scale simulation capabilities of the new DOE Center for Integrated Nanotechnologies, the University of New Mexico, and Sandia National Laboratories. Our main goals are to elucidate the processes involved in the photocatalytic growth of metal nanomaterials and provide the scientific basis for controlled synthesis. The nanomaterials resulting from these studies have applications in nanoelectronics, photonics, sensors, catalysis, and micromechanical systems. The proposed nanoscience concentrates on three thematic research areas: (1) the creation of nanoscale structures for realizing novel phenomena and quantum control, (2) understanding nanoscale processes in the environment, and (3) the development and use of multi-scale, multi-phenomena theory and simulation. Our goals for FY03 have been to understand the role of photocatalysis in the synthesis of dendritic platinum nanostructures grown from aqueous surfactant solutions under ambient

  19. The dynamic of the annual carbon allocation to wood in European tree species is consistent with a combined source-sink limitation of growth: implications for modelling

    NASA Astrophysics Data System (ADS)

    Guillemot, J.; Martin-StPaul, N. K.; Dufrene, E.; Francois, C.; Soudani, K.; Ourcival, J. M.; Delpierre, N.

    2015-05-01

    The extent to which wood growth is limited by carbon (C) supply (i.e. source control) or by cambial activity (i.e. sink control) will strongly determine the responses of trees to global changes. Nevertheless, the physiological processes that are responsible for limiting forest growth are still a matter of debate. The aim of this study was to evaluate the key determinants of the annual C allocation to wood along large soil and climate regional gradients over France. The study was conducted for five tree species representative of the main European forest biomes (Fagus sylvatica, Quercus petraea, Quercus ilex, Quercus robur and Picea abies). The drivers of stand biomass growth were assessed on both inter-site and inter-annual scales. Our data set comprised field measurements performed at 49 sites (931 site-years) that included biometric measurements and a variety of stand characteristics (e.g. soil water holding capacity, leaf area index). It was complemented with process-based simulations when possible explanatory variables could not be directly measured (e.g. annual and seasonal tree C balance, bioclimatic water stress indices). Specifically, the relative influences of tree C balance (source control), direct environmental control (water and temperature controls of sink activity) and allocation adjustments related to age, past climate conditions, competition intensity and soil nutrient availability on growth were quantified. The inter-site variability in the stand C allocation to wood was predominantly driven by age-related decline. The direct effects of temperature and water stress on sink activity (i.e. effects independent from their effects on the C supply) exerted a strong influence on the annual stand wood growth in all of the species considered, including deciduous temperate species. The lagged effect of the past environmental conditions (e.g. the previous year's water stress and low C uptake) significantly affected the annual C allocation to wood. The C supply

  20. Vascular rings.

    PubMed

    Backer, Carl L; Mongé, Michael C; Popescu, Andrada R; Eltayeb, Osama M; Rastatter, Jeffrey C; Rigsby, Cynthia K

    2016-06-01

    The term vascular ring refers to congenital vascular anomalies of the aortic arch system that compress the esophagus and trachea, causing symptoms related to those two structures. The most common vascular rings are double aortic arch and right aortic arch with left ligamentum. Pulmonary artery sling is rare and these patients need to be carefully evaluated for frequently associated tracheal stenosis. Another cause of tracheal compression occurring only in infants is the innominate artery compression syndrome. In the current era, the diagnosis of a vascular ring is best established by CT imaging that can accurately delineate the anatomy of the vascular ring and associated tracheal pathology. For patients with a right aortic arch there recently has been an increased recognition of a structure called a Kommerell diverticulum which may require resection and transfer of the left subclavian artery to the left carotid artery. A very rare vascular ring is the circumflex aorta that is now treated with the aortic uncrossing operation. Patients with vascular rings should all have an echocardiogram because of the incidence of associated congenital heart disease. We also recommend bronchoscopy to assess for additional tracheal pathology and provide an assessment of the degree of tracheomalacia and bronchomalacia. The outcomes of surgical intervention are excellent and most patients have complete resolution of symptoms over a period of time. PMID:27301603

  1. Spark ignited turbulent flame kernel growth. Annual report, January--December 1991

    SciTech Connect

    Santavicca, D.A.

    1994-06-01

    An experimental study of the effect of spark power on the growth rate of spark-ignited flame kernels was conducted in a turbulent flow system at 1 atm, 300 K conditions. All measurements were made with premixed, propane-air at a fuel/air equivalence ratio of 0.93, with 0%, 8% or 14% dilution. Two flow conditions were studied: a low turbulence intensity case with a mean velocity of 1.25 m/sec and a turbulence intensity of 0.33 m/sec, and a high turbulence intensity case with a mean velocity of 1.04 m/sec and a turbulence intensity of 0.88 m/sec. The growth of the spark-ignited flame kernel was recorded over a time interval from 83 {mu}sec to 20 msec following the start of ignition using high speed laser shadowgraphy. In order to evaluate the effect of ignition spark power, tests were conducted with a long duration (ca 4 msec) inductive discharge ignition system with an average spark power of ca 14 watts and two short duration (ca 100 nsec) breakdown ignition systems with average spark powers of ca 6 {times} 10{sup 4} and ca 6 {times} 10{sup 5} watts. The results showed that increased spark power resulted in an increased growth rate, where the effect of short duration breakdown sparks was found to persist for times of the order of milliseconds. The effectiveness of increased spark power was found to be less at high turbulence and high dilution conditions. Increased spark power had a greater effect on the 0--5 mm burn time than on the 5--13 mm burn time, in part because of the effect of breakdown energy on the initial size of the flame kernel. And finally, when spark power was increased by shortening the spark duration while keeping the effective energy the same there was a significant increase in the misfire rate, however when the spark power was further increased by increasing the breakdown energy the misfire rate dropped to zero.

  2. Variation of Maximum Tree Height and Annual Shoot Growth of Smith Fir at Various Elevations in the Sygera Mountains, Southeastern Tibetan Plateau

    PubMed Central

    Wang, Yafeng; Čufar, Katarina; Eckstein, Dieter; Liang, Eryuan

    2012-01-01

    Little is known about tree height and height growth (as annual shoot elongation of the apical part of vertical stems) of coniferous trees growing at various altitudes on the Tibetan Plateau, which provides a high-elevation natural platform for assessing tree growth performance in relation to future climate change. We here investigated the variation of maximum tree height and annual height increment of Smith fir (Abies georgei var. smithii) in seven forest plots (30 m×40 m) along two altitudinal transects between 3,800 m and 4,200/4,390 m above sea level (a.s.l.) in the Sygera Mountains, southeastern Tibetan Plateau. Four plots were located on north-facing slopes and three plots on southeast-facing slopes. At each site, annual shoot growth was obtained by measuring the distance between successive terminal bud scars along the main stem of 25 trees that were between 2 and 4 m high. Maximum/mean tree height and mean annual height increment of Smith fir decreased with increasing altitude up to the tree line, indicative of a stress gradient (the dominant temperature gradient) along the altitudinal transect. Above-average mean minimum summer (particularly July) temperatures affected height increment positively, whereas precipitation had no significant effect on shoot growth. The time series of annual height increments of Smith fir can be used for the reconstruction of past climate on the southeastern Tibetan Plateau. In addition, it can be expected that the rising summer temperatures observed in the recent past and anticipated for the future will enhance Smith fir's growth throughout its altitudinal distribution range. PMID:22396738

  3. Variation of maximum tree height and annual shoot growth of Smith fir at various elevations in the Sygera Mountains, southeastern Tibetan Plateau.

    PubMed

    Wang, Yafeng; Čufar, Katarina; Eckstein, Dieter; Liang, Eryuan

    2012-01-01

    Little is known about tree height and height growth (as annual shoot elongation of the apical part of vertical stems) of coniferous trees growing at various altitudes on the Tibetan Plateau, which provides a high-elevation natural platform for assessing tree growth performance in relation to future climate change. We here investigated the variation of maximum tree height and annual height increment of Smith fir (Abies georgei var. smithii) in seven forest plots (30 m×40 m) along two altitudinal transects between 3,800 m and 4,200/4,390 m above sea level (a.s.l.) in the Sygera Mountains, southeastern Tibetan Plateau. Four plots were located on north-facing slopes and three plots on southeast-facing slopes. At each site, annual shoot growth was obtained by measuring the distance between successive terminal bud scars along the main stem of 25 trees that were between 2 and 4 m high. Maximum/mean tree height and mean annual height increment of Smith fir decreased with increasing altitude up to the tree line, indicative of a stress gradient (the dominant temperature gradient) along the altitudinal transect. Above-average mean minimum summer (particularly July) temperatures affected height increment positively, whereas precipitation had no significant effect on shoot growth. The time series of annual height increments of Smith fir can be used for the reconstruction of past climate on the southeastern Tibetan Plateau. In addition, it can be expected that the rising summer temperatures observed in the recent past and anticipated for the future will enhance Smith fir's growth throughout its altitudinal distribution range. PMID:22396738

  4. Reconfiguration of tree architecture under the effect of wind, competition for light, and annual growth

    NASA Astrophysics Data System (ADS)

    Eloy, Christophe

    2015-11-01

    In general, trees have self-similar architectures with longer and thicker branches near the roots. Yet, branch segments grown each year always have approximately the same length. This hierarchy of branch lengths and the whole self-similar characteristics results in fact from a continuous process of growth of new branches and shedding of old ones. To assess how such a process affects tree architecture, a functional-structural mechanically-based model of virtual trees is developed. In this model, trees grow into fractal structures to promote efficient photosynthesis in a competing environment. In addition, branch diameters increase in response to wind-induced loads. The results of this model suggest that most self-similar characteristics of trees can be explained by considering that tree are growing structure able to resist mechanical loads due to wind efficiently.

  5. Modelling Growth and Partitioning of Annual Above-Ground Vegetative and Reproductive Biomass of Grapevine

    NASA Astrophysics Data System (ADS)

    Meggio, Franco; Vendrame, Nadia; Maniero, Giovanni; Pitacco, Andrea

    2014-05-01

    In the current climate change scenarios, both agriculture and forestry inherently may act as carbon sinks and consequently can play a key role in limiting global warming. An urgent need exists to understand which land uses and land resource types have the greatest potential to mitigate greenhouse gas (GHG) emissions contributing to global change. A common believe is that agricultural fields cannot be net carbon sinks due to many technical inputs and repeated disturbances of upper soil layers that all contribute to a substantial loss both of the old and newly-synthesized organic matter. Perennial tree crops (vineyards and orchards), however, can behave differently: they grow a permanent woody structure, stand undisturbed in the same field for decades, originate a woody pruning debris, and are often grass-covered. In this context, reliable methods for quantifying and modelling emissions and carbon sequestration are required. Carbon stock changes are calculated by multiplying the difference in oven dry weight of biomass increments and losses with the appropriate carbon fraction. These data are relatively scant, and more information is needed on vineyard management practices and how they impact vineyard C sequestration and GHG emissions in order to generate an accurate vineyard GHG footprint. During the last decades, research efforts have been made for estimating the vineyard carbon budget and its allocation pattern since it is crucial to better understand how grapevines control the distribution of acquired resources in response to variation in environmental growth conditions and agronomic practices. The objective of the present study was to model and compare the dynamics of current year's above-ground biomass among four grapevine varieties. Trials were carried out over three growing seasons in field conditions. The non-linear extra-sums-of-squares method demonstrated to be a feasible way of growth models comparison to statistically assess significant differences among

  6. A cluster of stratospheric volcanic eruptions in the AD 530s recorded in Siberian tree rings

    NASA Astrophysics Data System (ADS)

    Churakova (Sidorova), Olga V.; Bryukhanova, Marina V.; Saurer, Matthias; Boettger, Tatjana; Naurzbaev, Mukhtar M.; Myglan, Vladimir S.; Vaganov, Eugene A.; Hughes, Malcolm K.; Siegwolf, Rolf T. W.

    2014-11-01

    Recently published, improved chronologies for volcanic sulfate in Greenland and Antarctic ice permit a comparison of the growth responses of absolutely annually dated tree rings at three locations in Siberia with annual ice-core records of volcanic eruptions centered on AD 536. For the first time for this region and period, we present unique data sets for tree-ring width, cell-wall thickness, δ13C and δ18O in cellulose. These were based on multiple samples from relict wood of larch obtained from two sites close to the northern limit of tree growth on the Taimyr Peninsula and in northeastern Yakutia, and at a high-elevation, location 20° further South in the Altai Mts. An event in AD 536 was associated with different, but marked, changes in tree-ring parameters at the high-latitude sites compared with the high elevation site. An AD 541 event was associated with its own distinctive tree-ring responses across the three sites and multiple variables. The years after AD 532 were marked by a strong and sustained decrease in growth at the high-elevation, more southerly, site. The combination of improved ice-core chronology for the climatically effective volcanic eruptions of this part of the 6th century AD, and an array of tree-ring sites with different climates and multiple tree-ring variables permits a richer description of tree responses to this cluster of events. The pattern of tree-ring parameter responses at the three locations in AD 536, AD 541, and perhaps AD 532 is consistent with responses to climatically effective volcanic eruptions influencing tree response in those and subsequent years.

  7. [Effects of elevated ozone on Pinus armandii growth: a simulation study with open-top chamber].

    PubMed

    Liu, Chang-Fu; Liu, Chen; He, Xing-Yuan; Ruan, Ya-Nan; Xu, Sheng; Chen, Zhen-Ju; Peng, Jun-Jie; Li, Teng

    2013-10-01

    By using open-top chamber (OTC) and the techniques of dendrochronology, this paper studied the growth of Pinus armandii under elevated ozone, and explored the evolution dynamics and adaptation mechanisms of typical forest ecosystems to ozone enrichment. Elevated ozone inhibited the stem growth of P. armandii significantly, with the annual growth of the stem length and diameter reduced by 35.0% and 12.9%, respectively. The annual growth of tree-ring width and the annual ring cells number decreased by 11.5% and 54.1%, respectively, but no significant change was observed in the diameter of tracheid. At regional scale, the fluctuation of ozone concentration showed significant correlation with the variation of local vegetation growth (NDVI). PMID:24483064

  8. Upper air teleconnections to Ob River flows and tree rings

    NASA Astrophysics Data System (ADS)

    Meko, David; Panyushkina, Irina; Agafonov, Leonid

    2015-04-01

    The Ob River, one of the world's greatest rivers, with a catchment basin about the size of Western Europe, contributes 12% or more of the annual freshwater inflow to the Arctic Ocean. The input of heat and fresh water is important to the global climate system through effects on sea ice, salinity, and the thermohaline circulation of the ocean. As part of a tree-ring project to obtain multi-century long information on variability of Ob River flows, a network of 18 sites of Pinus, Larix, Populus and Salix has been collected along the Ob in the summers of 2013 and 2014. Analysis of collections processed so far indicates a significant relationship of tree-growth to river discharge. Moderation of the floodplain air temperature regime by flooding appears to be an important driver of the tree-ring response. In unraveling the relationship of tree-growth to river flows, it is important to identify atmospheric circulation features directly linked to observed time series variations of flow and tree growth. In this study we examine statistical links between primary teleconnection modes of Northern Hemisphere upper-air (500 mb) circulation, Ob River flow, and tree-ring chronologies. Annual discharge at the mouth of the Ob River is found to be significantly positively related to the phase of the East Atlantic (EA) pattern, the second prominent mode of low-frequency variability over the North Atlantic. The EA pattern, consisting of a north-south dipole of pressure-anomaly centers spanning the North Atlantic from east to west, is associated with a low-pressure anomaly centered over the Ob River Basin, and with a pattern of positive precipitation anomaly of the same region. The positive correlation of discharge and EA is consistent with these know patterns, and is contrasted with generally negative (though smaller) correlations between EA and tree-ring chronologies. The signs of correlations are consistent with a conceptual model of river influence on tree growth through air

  9. Storage Rings

    SciTech Connect

    Fischer, W.

    2011-01-01

    Storage rings are circular machines that store particle beams at a constant energy. Beams are stored in rings without acceleration for a number of reasons (Tab. 1). Storage rings are used in high-energy, nuclear, atomic, and molecular physics, as well as for experiments in chemistry, material and life sciences. Parameters for storage rings such as particle species, energy, beam intensity, beam size, and store time vary widely depending on the application. The beam must be injected into a storage ring but may not be extracted (Fig. 1). Accelerator rings such as synchrotrons are used as storage rings before and after acceleration. Particles stored in rings include electrons and positrons; muons; protons and anti-protons; neutrons; light and heavy, positive and negative, atomic ions of various charge states; molecular and cluster ions, and neutral polar molecules. Spin polarized beams of electrons, positrons, and protons were stored. The kinetic energy of the stored particles ranges from 10{sup -6} eV to 3.5 x 10{sup 12} eV (LHC, 7 x 10{sup 12} eV planned), the number of stored particles from one (ESR) to 1015 (ISR). To store beam in rings requires bending (dipoles) and transverse focusing (quadrupoles). Higher order multipoles are used to correct chromatic aberrations, to suppress instabilities, and to compensate for nonlinear field errors of dipoles and quadrupoles. Magnetic multipole functions can be combined in magnets. Beams are stored bunched with radio frequency systems, and unbunched. The magnetic lattice and radio frequency system are designed to ensure the stability of transverse and longitudinal motion. New technologies allow for better storage rings. With strong focusing the beam pipe dimensions became much smaller than previously possible. For a given circumference superconducting magnets make higher energies possible, and superconducting radio frequency systems allow for efficient replenishment of synchrotron radiation losses of large current electron or

  10. An annual cycle of recruitment, growth and production in a Malaysian population of the trochacean gastropod Umbonium vestiarium (L.)

    NASA Astrophysics Data System (ADS)

    Berry, A. J.; bin Othman, Zamri

    1983-09-01

    From July 1981 to July 1982 Umbonium vestiarium (L.) on a north Penang sand shore numbered 573-11 077 m -2 (mean 4126 or 53·1 g dry tissue) near MLWN and 2164-12 414 m -2 (mean 6500 or 59·8 g dry tissue) further downshore. Heavy recruitment of young became evident in June and July 1982 and a closely corresponding cohort of young was present in July 1981. Progression of this cohort indicated that young settling in May-June grew to full size (11-13 mm diameter) by January-March the following year and that virtually all died during their second year, presumably having spawned in March-May. Recruitment of young was chiefly on the lower shore but adults came to be more abundant and predominant on the upper shore. There is some evidence of migration upshore during growth. Production is estimated at 105·4 g dry tissue m -2 y -1 (2118 kj) at the lower shore level and this is almost double the 58·8 g m -2 y -1 (1176·6 kj) at the higher level. These values represent almost the entire secondary production across much of the sand flats. Possible causes of such a marked annual cycle in the very weakly seasonal tropics of the Malacca Strait are considered and it is suggested that monsoonal changes in wind, wave action and salinity might be involved.

  11. Ring Galaxies

    NASA Astrophysics Data System (ADS)

    Dennefeld, M.; Materne, J.

    1980-09-01

    Among the 338 exotic, intriguing and/or fascinating objects contained in Arp's catalogue of peculiar galaxies, two, Arp 146 and 147, are calling special attention as a presumably separate class of objects displaying closed rings with almost empty interior. It is difficult to find out when, historically speaking, attention was called first to this type of object as a peculiar class, but certainly ga1axies with rings were widely found and recognized in the early sixties, ul}der others by Vorontsov-Velyaminov (1960), Sandage (1961) in the Hubble Atlas or de Vaucouleurs (1964) in the first reference catalogue of ga1axies. The most recent estimates by Arp and Madore (1977) from a search on about 200 Schmidt plates covering 7,000 square degrees give 3.6 per cent of ring galaxies among 2,784 peculiar galaxies found. However, despite the mythological perfection associated with a circle, some ordering is necessary before trying to understand the nature of such objects. This is particularly true because a large fraction of those galaxies with rings are probably normal spiral galaxies of type RS or S(r) as defined by de Vaucouleurs, where the spiral arms are simply "closing the circle". A good example of such "ordinary" galaxy is NGC 3081 in the Hubble Atlas .

  12. Fog and Vegetation on the California Channel Islands: A Tree Ring and Satellite Analysis

    NASA Astrophysics Data System (ADS)

    Williams, P.; Still, C.; Fischer, D.; Leavitt, S.

    2005-12-01

    Tree-ring width and stable isotope composition of rare pines in Channel Islands National Park reflect annual variations in water availability. α-cellulose was isolated from Bishop Pine ( Pinus muricata) cores from Santa Cruz Island (SCI). Individual annual rings from 1979-2003 were analyzed for carbon-13 (n = 4 trees). An average δ13C chronology was created and annual atmospheric 13CO2 at La Jolla Pier, CA was subtracted to detrend the chronology for the steadily decreasing δ13C of atmospheric CO2 that has resulted from anthropogenic emissions and biomass burning. Early and latewood δ13C were negatively correlated with annual rainfall in the SCI central valley (r = -0.5057, r = -0.6447, respectively). An annual ring width chronology (1908-2004) was also created from Torrey Pine ( Pinus torreyana) tree cores (n=17) collected on Santa Rosa Island. Ring width was positively correlated with SCI rainfall (r = 0.6993). On average, 87% of this precipitation falls between November and March. However, tree growth as measured by dendrometer bands continues throughout the summer months suggesting an additional source of water. Summer is also the peak fog season for the Islands. The last rain of the 2004 growing season was on March 1 and monthly NDVI data derived from MODIS show that the vast majority of the vegetation on SCI was dormant by mid-May. When summer NDVI is overlaid on an image of average summer-time 10:30AM cloud cover, created using a derivative of the MODIS cloud-mask product, it appears that the greenest parts of SCI during summer months are those regions that experience the most summertime cloud cover. The distribution of Bishop Pine also seems to be limited to elevations that intercept cloud banks, as opposed to regions that simply experience cloud cover. It is therefore possible that these tree ring width and stable isotope records document the intensity of summer fog inundation in addition to rainfall. Because we have observed consistently significant

  13. Tree-ring δ13C and δ18O, leaf δ13C and wood and leaf N status demonstrate tree growth strategies and predict susceptibility to disturbance.

    PubMed

    Billings, S A; Boone, A S; Stephen, F M

    2016-05-01

    Understanding how tree growth strategies may influence tree susceptibility to disturbance is an important goal, especially given projected increases in diverse ecological disturbances this century. We use growth responses of tree rings to climate, relationships between tree-ring stable isotopic signatures of carbon (δ(13)C) and oxygen (δ(18)O), wood nitrogen concentration [N], and contemporary leaf [N] and δ(13)C values to assess potential historic drivers of tree photosynthesis in dying and apparently healthy co-occurring northern red oak (Quercus rubra L. (Fagaceae)) during a region-wide oak decline event in Arkansas, USA. Bole growth of both healthy and dying trees responded negatively to drought severity (Palmer Drought Severity Index) and temperature; healthy trees exhibited a positive, but small, response to growing season precipitation. Contrary to expectations, tree-ring δ(13)C did not increase with drought severity. A significantly positive relationship between tree-ring δ(13)C and δ(18)O was evident in dying trees (P < 0.05) but not in healthy trees. Healthy trees' wood exhibited lower [N] than that of dying trees throughout most of their lives (P < 0.05), and we observed a significant, positive relationship (P < 0.05) in healthy trees between contemporary leaf δ(13)C and leaf N (by mass), but not in dying trees. Our work provides evidence that for plants in which strong relationships between δ(13)C and δ(18)O are not evident, δ(13)C may be governed by plant N status. The data further imply that historic photosynthesis in healthy trees was linked to N status and, perhaps, C sink strength to a greater extent than in dying trees, in which tree-ring stable isotopes suggest that historic photosynthesis was governed primarily by stomatal regulation. This, in turn, suggests that assessing the relative dominance of photosynthetic capacity vs stomatal regulation as drivers of trees' C accrual may be a feasible means of predicting tree

  14. Sensitivity of growth and biomass allocation patterns to increasing nitrogen: a comparison between ephemerals and annuals in the Gurbantunggut Desert, north-western China

    PubMed Central

    Zhou, Xiaobing; Zhang, Yuanming; Niklas, Karl J.

    2014-01-01

    Background and Aims Biomass accumulation and allocation patterns are critical to quantifying ecosystem dynamics. However, these patterns differ among species, and they can change in response to nutrient availability even among genetically related individuals. In order to understand this complexity further, this study examined three ephemeral species (with very short vegetative growth periods) and three annual species (with significantly longer vegetative growth periods) in the Gurbantunggut Desert, north-western China, to determine their responses to different nitrogen (N) supplements under natural conditions. Methods Nitrogen was added to the soil at rates of 0, 0·5, 1·0, 3·0, 6·0 and 24·0 g N m−2 year−1. Plants were sampled at various intervals to measure relative growth rate and shoot and root dry mass. Key Results Compared with annuals, ephemerals grew more rapidly, increased shoot and root biomass with increasing N application rates and significantly decreased root/shoot ratios. Nevertheless, changes in the biomass allocation of some species (i.e. Erodium oxyrrhynchum) in response to the N treatment were largely a consequence of changes in overall plant size, which was inconsistent with an optimal partitioning model. An isometric log shoot vs. log root scaling relationship for the final biomass harvest was observed for each species and all annuals, while pooled data of three ephemerals showed an allometric scaling relationship. Conclusions These results indicate that ephemerals and annuals differ observably in their biomass allocation patterns in response to soil N supplements, although an isometric log shoot vs. log root scaling relationship was maintained across all species. These findings highlight that different life history strategies behave differently in response to N application even when interspecific scaling relationships remain nearly isometric. PMID:24287812

  15. Effect of inter-annual variability in pasture growth and irrigation response on farm productivity and profitability based on biophysical and farm systems modelling.

    PubMed

    Vogeler, Iris; Mackay, Alec; Vibart, Ronaldo; Rendel, John; Beautrais, Josef; Dennis, Samuel

    2016-09-15

    Farm system and nutrient budget models are increasingly being used in analysis to inform on farm decision making and evaluate land use policy options at regional scales. These analyses are generally based on the use of average annual pasture yields. In New Zealand (NZ), like in many countries, there is considerable inter-annual variation in pasture growth rates, due to climate. In this study a modelling approach was used to (i) include inter-annual variability as an integral part of the analysis and (ii) test the approach in an economic analysis of irrigation in a case study within the Hawkes Bay Region of New Zealand. The Agricultural Production Systems Simulator (APSIM) was used to generate pasture dry matter yields (DMY) for 20 different years and under both dryland and irrigation. The generated DMY were linked to outputs from farm-scale modelling for both Sheep and Beef Systems (Farmaxx Pro) and Dairy Systems (Farmax® Dairy Pro) to calculate farm production over 20 different years. Variation in DMY and associated livestock production due to inter-annual variation in climate was large, with a coefficient of variations up to 20%. Irrigation decreased this inter-annual variation. On average irrigation, with unlimited available water, increased income by $831 to 1195/ha, but when irrigation was limited to 250mm/ha/year income only increased by $525 to 883/ha. Using pasture responses in individual years to capturing the inter-annual variation, rather than the pasture response averaged over 20years resulted in lower financial benefits. In the case study income from irrigation based on an average year were 10 to >20% higher compared with those obtained from individual years. PMID:27203517

  16. Autosomal ring chromosomes in human genetic disorders

    PubMed Central

    2015-01-01

    Ring chromosomes arise following breakage and rejoining in both chromosome arms. They are heterogeneous with variable size and genetic content and can originate from any chromosome. Phenotypes associated with ring chromosomes are highly variable as apart from any deletion caused by ring formation, imbalances from ring instability can also occur. Of interest is ring chromosome 20 which has a significant association with epilepsy with seizure onset in early childhood. Severe growth deficiency without major malformations is a common finding in the ring chromosome carrier. This phenotype associated with ring behaviour and mitotic instability and independent of the chromosome involved has been termed the “ring syndrome”. Precise genotype-phenotype correlations for ring chromosomes may not be possible as influencing factors vary depending on the extent of deletion in ring formation, ring instability and the level of mosaicism. Although ring chromosomes usually arise as de novo events, familial transmission of rings from carrier to offspring has been described and prenatal diagnosis for any pregnancies should always be considered. PMID:26835370

  17. NSLS annual report 1984

    SciTech Connect

    Klaffky, R.; Thomlinson, W.

    1984-01-01

    The first comprehensive Annual Report of the National Synchrotron Light Source comes at a time of great activity and forward motion for the facility. In the following pages we outline the management changes that have taken place in the past year, the progress that has been made in the commissioning of the x-ray ring and in the enhanced utilization of the uv ring, together with an extensive discussion of the interesting scientific experiments that have been carried out.

  18. Physics of planetary rings

    NASA Astrophysics Data System (ADS)

    Gorkavyi, N.

    2007-08-01

    It is difficult to enumerate all the surprises presented by the planetary rings. The Saturnian rings are stratified into thousands of ringlets and the Uranian rings are compressed into narrow streams, which for some reason or other differ from circular orbits like the wheel of an old bicycle. The edge of the rings is jagged and the rings themselves are pegged down under the gravitational pressure of the satellites, bending like a ship's wake. There are spiral waves, elliptical rings, strange interlacing of narrow ringlets, and to cap it all one has observed in the Neptunian ring system three dense, bright arcs - like bunches of sausages on a transparent string. For celestial mechanics this is a spectacle as unnatural as a bear's tooth in the necklace of the English queen. In the dynamics of planetary rings the physics of collective interaction was supplemented by taking collisions between particles into account. One was led to study a kinetic equation with a rather complex collision integral - because the collisions are inelastic - which later on made it possible, both by using the Chapman-Enskog method and by using the solution of the kinetic equation for a plasma in a magnetic field, to reduce it to a closed set of (hydrodynamical) moment equations [1]. The hydrodynamical instabilities lead to the growth of short-wavelength waves and large-scale structures of the Saturnian rings [1]. We have shown that the formation of the existing dense Uranian rings is connected with the capture of positively drifting ring particles in inner Lindblad resonances which arrest this drift [1]. After the formation of dense rings at the positions of satellite resonances the collective interaction between resonant particles is amplified and the rings can leave the resonance and drift away from the planet and the parent resonance. We can expect in the C ring an appreciable positive ballistic particle drift caused by the erosion of the B ring by micrometeorites. It is therefore natural

  19. Ringing wormholes

    SciTech Connect

    Konoplya, R.A.; Molina, C.

    2005-06-15

    We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (ringing) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.

  20. Biophysical modelling of intra-ring variations in tracheid features and wood density of Pinus pinaster trees exposed to seasonal droughts.

    PubMed

    Wilkinson, Sarah; Ogée, Jérôme; Domec, Jean-Christophe; Rayment, Mark; Wingate, Lisa

    2015-03-01

    Process-based models that link seasonally varying environmental signals to morphological features within tree rings are essential tools to predict tree growth response and commercially important wood quality traits under future climate scenarios. This study evaluated model portrayal of radial growth and wood anatomy observations within a mature maritime pine (Pinus pinaster (L.) Aït.) stand exposed to seasonal droughts. Intra-annual variations in tracheid anatomy and wood density were identified through image analysis and X-ray densitometry on stem cores covering the growth period 1999-2010. A cambial growth model was integrated with modelled plant water status and sugar availability from the soil-plant-atmosphere transfer model MuSICA to generate estimates of cell number, cell volume, cell mass and wood density on a weekly time step. The model successfully predicted inter-annual variations in cell number, ring width and maximum wood density. The model was also able to predict the occurrence of special anatomical features such as intra-annual density fluctuations (IADFs) in growth rings. Since cell wall thickness remained surprisingly constant within and between growth rings, variations in wood density were primarily the result of variations in lumen diameter, both in the model and anatomical data. In the model, changes in plant water status were identified as the main driver of the IADFs through a direct effect on cell volume. The anatomy data also revealed that a trade-off existed between hydraulic safety and hydraulic efficiency. Although a simplified description of cambial physiology is presented, this integrated modelling approach shows potential value for identifying universal patterns of tree-ring growth and anatomical features over a broad climatic gradient. PMID:25769337

  1. The dynamics of annual carbon allocation to wood in European forests is consistent with a combined source-sink limitation of growth.

    NASA Astrophysics Data System (ADS)

    Guillemot, Joannès; Martin-StPaul, Nicolas K.; Dufrêne, Eric; François, Christophe; Soudani, Kamel; Ourcival, Jean-Marc; Leadley, Paul; Delpierre, Nicolas

    2015-04-01

    The extent to which forest growth is limited by carbon (C) supply (source control) or by cambial activity (sink control) will strongly determines the responses of trees to global changes. However, the physiological processes responsible for the limitation of forest growth are still under debate. The aim of this study was i) to evaluate the key drivers of the annual carbon allocation to wood along large soil and climate regional gradients in four tree species representative of the main European forest biomes (Fagus sylvatica, Quercus petraea, Quercus ilex and Picea abies) ii) to implement the identified key drivers in a new C allocation scheme within the CASTANEA terrestrial biosphere model (TBM). Combining field measurements and process-based simulations at 49 sites (931 site-years), our analyses revealed that the inter-site variability in C allocation to wood was predominantly driven by an age-related decline. The direct control of temperature or water stress on sink activity (i.e. independently from their effects on C supply) exerted a strong influence on the annual woody growth in all the species considered, including deciduous temperate species. The lagged effect of the past environment conditions was a significant driver of the annual C allocation to wood. Carbon supply appeared to strongly limit growth only in deciduous temperate species. Our study supports the premise that European forest growth is under a complex panel of source- and sink- limitations, contradicting the simple source control implemented in most TBMs. The implementation of these combined forest growth limitations in the CASTANEA model significantly improved its performance when evaluated against independent stand growth data at the regional scale (mainland France, >10000 plots). We finally discuss how the sink imitation affects the CASTANEA simulated projections of forest productivity along the 21th century, especially with respect to the expected fertilizing effect of increasing atmospheric

  2. Effects of agaricus lilaceps fairy rings on soil aggregation and microbial community structure in relation to growth stimulation of western wheatgrass (pascopyrum smithii) in Eastern Montana rangeland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stimulation of plant productivity caused by Agaricus fairy rings has been reported, but nothing is known about soil aggregation and the microbial community structure of the stimulated zone, particularly the communities that can bind to soil particles. We studied three concentric zones of Agaricus li...

  3. Structural disorder and transformation in crystal growth: direct observation of ring-opening isomerization in a metal–organic solid solution

    PubMed Central

    Jiang, Ji-Jun; He, Jian-Rong; Lü, Xing-Qiang; Wang, Da-Wei; Li, Guo-Bi; Su, Cheng-Yong

    2014-01-01

    A rare example is reported in which discrete Ag2 L 2 ring and (AgL)∞ chain motifs [L = N,N′-bis(3-imidazol-1-yl-propyl)-pyromellitic diimide] co-crystallize in the same crystal lattice with varying ratios and degrees of disorder. Crystal structures obtained from representative crystals reveal compatible packing arrangements of the cyclic and polymeric isomers within the crystal lattice, which enables them to co-exist within a crystalline solid solution. A feasible pathway for transformation between the isomers is suggested via facile rotation of the coordinating imidazolyl groups. This chemical system could provide a chance for direct observation of ring-opening isomerization at the crystal surface. Mass spectrometry and 1H NMR titration show a dynamic equilibrium between cyclic and oligomeric species in solution, and a potential crystallization process is suggested involving alignment of precursors directed by aromatic stacking interactions between pyromellitic diimide units, followed by ring-opening isomerization at the interface between the solid and the solution. Both cyclic and oligomeric species can act as precursors, with interconversion between them being facile due to a low energy barrier for rotation of the imidazole rings. Thermogravimetric analysis and variable-temperature powder X-ray diffraction indicate a transition to a different crystalline phase around 120°C, which is associated with loss of solvent from the crystal lattice. PMID:25295173

  4. Tree-ring analysis of teak ( Tectona grandis L.F.) in central India and its relationship with rainfall and moisture index

    NASA Astrophysics Data System (ADS)

    Ram, Somaru; Borgaonkar, H. P.; Sikder, A. B.

    2008-10-01

    Tree-ring-width index chronologies of teak ( Tectona grandis L.F.) from three sites in central India have been studied for their dendroclimatic potential. The existence of good correlation among the three site chronologies indicates the influence of common forcing factor to the tree growth of the region. Tree growth and climate relationship based on correlation analysis revealed the important contribution of moisture index and rainfall rather than the direct influence of the temperature on tree growth during different seasons. Significant positive relationship of moisture index and rainfall during the monsoon months as well as on the annual scale with tree-ring width variations over the region indicates the important role of moisture availability at the root zone. The results suggest that the teak tree-ring chronologies can be used as high resolution proxy for past precipitation and moisture level in the environment.

  5. The Dynamic of Annual Carbon Allocation to Wood in European Forests Is Consistent with a Combined Source-Sink Limitation of Growth: Implications on Growth Simulations in a Terrestrial Biosphere Model

    NASA Astrophysics Data System (ADS)

    Guillemot, J.; Martin-StPaul, N. K.; Dufrêne, E.; François, C.; Soudani, K.; Ourcival, J. M.; Leadley, P.; Delpierre, N.

    2014-12-01

    The extent to which forest growth is limited by carbon (C) supply (source control) or by cambial activity (sink control) will strongly determines the responses of trees to global changes. However, the physiological processes responsible for the limitation of forest growth are still under debate. The aim of this study was i) to evaluate the key drivers of the annual carbon allocation to wood along large soil and climate regional gradients in four tree species representative of the main European forest biomes (Fagus sylvatica, Quercus petraea, Quercus ilex and Picea abies) ii) to implement the identified key drivers in a new C allocation scheme within the CASTANEA terrestrial biosphere model (TBM). Combining field measurements and process-based simulations at 49 sites (931 site-years), our analyses revealed that the inter-site variability in C allocation to wood was predominantly driven by an age-related decline. The direct control of temperature or water stress on sink activity (i.e. independently from their effects on C supply) exerted a strong influence on the annual woody growth in all the species considered, including deciduous temperate species. The lagged effect of the past environment conditions was a significant driver of the annual C allocation to wood. Carbon supply appeared to strongly limit growth only in deciduous temperate species. Our study supports the premise that European forest growth is under a complex panel of source- and sink- limitations, contradicting the simple source control implemented in most TBMs. The implementation of these combined forest growth limitations in the CASTANEA model significantly improved its performance when evaluated against independent stand growth data at the regional scale (mainland France, >103 plots). We finally discuss how the sink imitation affects the CASTANEA simulated projections of forest productivity along the 21th century, especially with respect to the expected fertilizing effect of increasing atmospheric

  6. For Profit Child Care: Four Decades of Growth. Nineteenth Annual Status Report on For Profit Child Care

    ERIC Educational Resources Information Center

    Neugebauer, Roger

    2006-01-01

    For decades "Exchange" magazine has tracked the growth of the for profit child care sector. In this article, the author reflects on trends in the for profit sector over the past four decades. Overall, it has been a period of tremendous growth for the for profit sector. However, it has also been characterized by alternating periods of rapid growth,…

  7. Wet season precipitation during the past century reconstructed from tree-rings of a tropical dry forest in Southern Ecuador

    NASA Astrophysics Data System (ADS)

    Pucha-Cofrep, Darwin; Peters, Thorsten; Bräuning, Achim

    2015-10-01

    This study investigates the dendroclimatic potential of tree species in a tropical dry forest in southern Ecuador. From 10 selected tree species, Bursera graveolens and Maclura tinctoria exhibited distinct annual and cross-datable tree-rings. It was possible to synchronize individual tree-ring series and to establish two tree-ring chronologies of 203 and 87 years length, respectively. The characteristic ENSO frequency band is reflected in wavelet power spectra of both chronologies. Both species show a strong correlation between ring width and precipitation of the wet season (January-May). Strong El Niño events (1972, 1983 and 1998) lead to strong growth responses in the tree-ring chronologies, whereas 'normal' ENSO events do not trigger long-lasting growth responses. The first ring-width based wet-season precipitation reconstruction for the past 103 years was developed. Statistical and spatial correlation analysis verified the skills of the reconstructed precipitation which captures a great part of the Rainfall Index over the land area of Ecuador and the equatorial Pacific. Furthermore, teleconnections with central Pacific precipitation and SST patterns were found.

  8. Microwave-assisted stereoselective approach to novel steroidal ring D-fused 2-pyrazolines and an evaluation of their cell-growth inhibitory effects in vitro.

    PubMed

    Mótyán, Gergő; Kovács, Ferenc; Wölfling, János; Gyovai, András; Zupkó, István; Frank, Éva

    2016-08-01

    Novel ring D-condensed 2-pyrazolines in the Δ(5)-androstene series were efficiently synthesized from 16-dehydropregnenolone or its acetate with different arylhydrazines or methylhydrazine, respectively, under microwave irradiation. The reactions are assumed to occur via hydrazone intermediates, followed by intramolecular 1,4-addition leading to the fused heteroring stereoselectively with a 16α,17α-cis ring junction. The synthesized compounds were subjected to in vitro pharmacological studies of their antiproliferative activities against four human breast (MCF7, T47D, MDA-MB-231 and MDA-MB-361) and three cervical (HeLa, C33A and SiHA) malignant cell lines. Flow cytometry revealed that the most potent agent elicited a cell cycle disturbance. PMID:27154752

  9. Technical Note: An improved guideline for rapid and precise sample preparation of tree-ring stable isotope analysis

    NASA Astrophysics Data System (ADS)

    Schollaen, K.; Baschek, H.; Heinrich, I.; Helle, G.

    2015-07-01

    The procedure of wood sample preparation, including tree-ring dissection, cellulose extraction, homogenization and finally weighing and packing for stable isotope analysis is labour intensive and time consuming. We present an elaborated methodical guideline from pre-analyses considerations, wood sample preparation through semi-automated chemical extraction of cellulose directly from tree-ring cross-sections to tree-ring dissection for high-precision isotope ratio mass spectrometry. This guideline reduces time and maximizes the tree-ring stable isotope data throughput significantly. The method was applied to ten different tree species (coniferous and angiosperm wood) with different wood growth rates and differently shaped tree-ring boundaries. The tree-ring structures of the cellulose cross-sections largely remained well identifiable. FTIR (Fourier transform infrared) spectrometry and the comparison of stable isotope values with classical method confirm chemical purity of the resultant cellulose. Sample homogenization is no longer necessary. Cellulose extraction is now faster, cheaper and more user friendly allowing (i) the simultaneous treatment of wood cross-sections of a total length of 180 cm (equivalent to 6 increment cores of 30 cm length) and thickness of 0.5 to 2 mm, and (ii) precise tree-ring separation at annual to high-resolution scale utilizing manual devices or UV-laser microdissection microscopes.

  10. Regional Chains Driving Growth of for Profit Child Care Sector: Twentieth Annual Status Report on for Profit Child Care

    ERIC Educational Resources Information Center

    Neugebauer, Roger

    2007-01-01

    In this article, the author highlights two main efforts in line with the historic twentieth annual status report on for profit child care. These includes: (1) adding new players in the "Exchanged Top 40" list; and (2) focusing on regional chains, organizations providing early childhood services in more than 20 locations in two or more states. The…

  11. Seed size effects on early seedling growth and response to applied nitrogen in annual ryegrass (Lolium multiflorum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of individual plants as experimental units may be necessary when resources are limited, but inter-plant variation risks obscuring differences among treatments. Experiments were undertaken to measure the effects of seed size on seedling size and response to applied nitrogen of annual ryegrass (Lo...

  12. DYNAMIC STANDARDIZATION OF TREE-RING SERIES

    EPA Science Inventory

    The compound growth function of Warren (W.G. Warren, 1980. ree-Ring Bull. 40:35-44) represented an attempt to develop a model-based approach that standardized tree ring width sequences and was more flexible than the monotonic functions that were then commonly used. hile the idea ...

  13. Reconstructing Tritium Exposure Using Tree Rings at Lawrence Berkeley National Laboratory, California

    PubMed Central

    LOVE, ADAM H.; HUNT, JAMES R.; KNEZOVICH, JOHN P.

    2010-01-01

    Annual tritium exposures were reconstructed using tree cores from Pinus jeffreyi and Eucalyptus globulus near a tritiated water vapor release stack. Both tritium (3H) and carbon-14 (14C) from the wood were measured from milligram samples using accelerator mass spectrometry. Because the annual nature of the eucalyptus tree rings was in doubt, 14C measurements provided growth rates used to estimate the age for 3H determinations. A 30-yr comparison of organically bound tritium (OBT) levels to reported 3H release data is achieved using OBT measurements from three trees near the stack. The annual average 3H, determined from atmospheric water vapor monitoring stations, is comparable to the OBT in proximal trees. For situations without adequate historical monitoring data, this measurement-based historical assessment provides the only independent means of assessing exposure as compared to fate and transport models that require prior knowledge of environmental conditions and 3H discharge patterns. PMID:14572081

  14. Asymmetric dipolar ring

    DOEpatents

    Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

    2010-11-16

    A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

  15. Biological Basis of Tree-Ring Formation: A Crash Course

    PubMed Central

    Rathgeber, Cyrille B. K.; Cuny, Henri E.; Fonti, Patrick

    2016-01-01

    Wood is of crucial importance for man and biosphere. In this mini review, we present the fundamental processes involved in tree-ring formation and intra-annual dynamics of cambial activity, along with the influences of the environmental factors. During wood formation, new xylem cells produced by the cambium are undergoing profound transformations, passing through successive differentiation stages, which enable them to perform their functions in trees. Xylem cell formation can be divided in five major phases: (1) the division of a cambial mother cell that creates a new cell; (2) the enlargement of this newly formed cell; (3) the deposition of its secondary wall; (4) the lignification of its cell wall; and finally, (5) its programmed cell death. In most regions of the world cambial activity follows a seasonal cycle. At the beginning of the growing season, when temperature increases, the cambium resumes activity, producing new xylem cells. These cells are disposed along radial files, and start their differentiation program according to their birth date, creating typical developmental strips in the forming xylem. The width of these strips smoothly changes along the growing season. Finally, when climatic conditions deteriorate (temperature or water availability in particular), cambial activity stops, soon followed by cell enlargement, and later on by secondary wall deposition. Without a clear understanding of the xylem formation process, it is not possible to comprehend how annual growth rings and typical wood structures are formed, recording normal seasonal variations of the environment as well as extreme climatic events. PMID:27303426

  16. Use of tree rings to investigate the onset of contamination of a shallow aquifer by chlorinated hydrocarbons

    USGS Publications Warehouse

    Yanosky, T.M.; Hansen, B.P.; Schening, M.R.

    2001-01-01

    Oaks (Quercus velutina Lam.) growing over a shallow aquifer contaminated by chlorinated hydrocarbons were studied to determine if it was possible to estimate the approximate year that contamination began. The annual rings of some trees downgradient from the contaminant release site contained elevated concentrations of chloride possibly derived from dechlorination of contaminants. Additionally, a radial-growth decline began in these trees at approximately the same time that chloride became elevated. Growth did not decline in trees that contained smaller concentrations of chloride. The source of elevated chloride and the corresponding reductions in tree growth could not be explained by factors other than contamination. On the basis of tree-ring evidence alone, the release occurred in the late 1960s or early 1970s. Contaminant release at a second location apparently occurred in the mid- to late 1970s, suggesting that the area was used for disposal for at least 5 years and possibly longer. Copyright ?? 2001 Elsevier Science B.V.

  17. Using Tree-Ring Data to Develop Critical Scientific and Mathematical Thinking Skills in Undergraduate Students

    NASA Astrophysics Data System (ADS)

    Fiondella, F.; Davi, N. K.; Wattenberg, F.; Pringle, P. T.; Greidanus, I.; Oelkers, R.

    2015-12-01

    Tree-ring science provides an engaging, intuitive, and relevant entryway into understanding both climate change and environmental research. It also sheds light on the process of science--from inspiration, to fieldwork, to analysis, to publishing and communication. The basic premise of dendrochronology is that annual rings reflect year-to-year environmental conditions and that by studying long-lived trees we can learn about environmental and climatic conditions going back hundreds to thousands of years. Conceptually, this makes tree-ring studies accessible to students and faculty for a number of reasons. First, in order to collect their data, dendrochronologists often launch expeditions to stunningly picturesque and remote places in search of long-lived, climate sensitive trees. The exciting stories and images that scientists bring back from the field can help connect students to the studies, their motivation, and the data collected. Second, tree rings can be more easily explained as a proxy for climate than ice cores, speleothems and others. Most people have prior knowledge about trees and annual growth rings. It is even possible, for example, for non-expert audiences to see climate variability through time with the naked eye by looking at climate-sensitive tree cores. Third, tree rings are interdisciplinary and illustrate the interplay between the mathematical sciences, the biological sciences, and the geosciences—that is, they show that the biosphere is a fundamental component of the Earth system. Here, we present online, multi-media learning modules for undergraduates that introduce students to several foundational studies in tree-ring science. These include evaluating tree-ring cores from ancient hemlock trees growing on a talus slope in New Paltz, NY to learn about drought in the Northeastern US, evaluating long-term streamflow and drought of the Colorado River based on tree-ring records, and using tree-ring dating techniques to develop construction

  18. Dendrochronology-based stand growth estimation of Larix olgensis forest in relation with climate on the eastern slope of Changbai Mountain, NE China

    NASA Astrophysics Data System (ADS)

    Lin, Bo; Xu, Qianqian; Liu, Wenhui; Zhang, Guochun; Xu, Qiongyao; Liu, Qijing

    2013-12-01

    The eastern slope of Changbai Mountain is characterized by pure larch forest ( Larix olgensis) with little human disturbance. Response of tree growth to climate in this area remains unknown. Meanwhile, little is known about how climate variations affect the biomass increase which could be recognized as a three-dimensional tree growth index. The objective of this study is to investigate the climate effects on the radial and biomass growth of larch on eastern slope of Changbai Mountain. Tree-ring width chronologies and mean annual biomass increment were established using tree-ring data. We used correlation analysis and multiple regression analysis to explore the relationship between larch growth and climatic factors from 1957 to 2009. Results show that tree-ring growth and mean annual biomass increment were primarily and significantly affected by previous year climatic variables with slight difference among months. Temperatures were more consistently and strongly correlated to the chronologies and mean annual biomass increment than was precipitation. Temperature is the main factor limiting larch growth on Changbai Mountain and the ongoing climate warming may accelerate the growth of the species. The current stand biomass of the area was 240.72 Mg·ha-1 and the annual stand biomass increment in 2009 was 2.91 Mg·ha-1. In conclusion, the old-growth forest in the study area is still accumulating carbon efficiently.

  19. The relationship between needle sugar carbon isotope ratios and tree rings of larch in Siberia.

    PubMed

    Rinne, K T; Saurer, M; Kirdyanov, A V; Loader, N J; Bryukhanova, M V; Werner, R A; Siegwolf, R T W

    2015-11-01

    Significant gaps still exist in our knowledge about post-photosynthetic leaf level and downstream metabolic processes and isotopic fractionations. This includes their impact on the isotopic climate signal stored in the carbon isotope composition (δ(13)C) of leaf assimilates and tree rings. For the first time, we compared the seasonal δ(13)C variability of leaf sucrose with intra-annual, high-resolution δ(13)C signature of tree rings from larch (Larix gmelinii Rupr.). The trees were growing at two sites in the continuous permafrost zone of Siberia with different growth conditions. Our results indicate very similar low-frequency intra-seasonal trends of the sucrose and tree ring δ(13)C records with little or no indication for the use of 'old' photosynthates formed during the previous year(s). The comparison of leaf sucrose δ(13)C values with that in other leaf sugars and in tree rings elucidates the cause for the reported (13)C-enrichment of sink organs compared with leaves. We observed that while the average δ(13)C of all needle sugars was 1.2‰ more negative than δ(13)C value of wood, the δ(13)C value of the transport sugar sucrose was on an average 1.0‰ more positive than that of wood. Our study shows a high potential of the combined use of compound-specific isotope analysis of sugars (leaf and phloem) with intra-annual tree ring δ(13)C measurements for deepening our understanding about the mechanisms controlling the isotope variability in tree rings under different environmental conditions. PMID:26433019

  20. Saturn's Spectacular Ring System

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Saturn's beautiful rings have fascinated astronomers since they were first observed by Galileo in 1610. The main rings consist of solid particles mostly in the 1 cm - 10 m range, composed primarily of water ice. The ring disk is exceptionally thin - the typical local thickness of the bright rings is tens of meters, whereas the diameter of the main rings is 250,000 km! The main rings exhibit substantial radial variations "ringlets", many of which are actively maintained via gravitational perturbations from Saturn's moons. Exterior to the main rings lie tenuous dust rings, which have little mass but occupy a very large volume of space. This seminar will emphasize the physics of ring-moon interactions, recent advances in our understanding of various aspects of the rings obtained from observations taken during 1995 when the rings appeared edge-on to the Earth and then to the Sun, and observations in subsequent years from HST.

  1. C3HC4-Type RING Finger Protein NbZFP1 Is Involved in Growth and Fruit Development in Nicotiana benthamiana

    PubMed Central

    Wu, Wenxian; Cheng, Zhiwei; Liu, Mengjie; Yang, Xiufen; Qiu, Dewen

    2014-01-01

    C3HC4-type RING finger proteins constitute a large family in the plant kingdom and play important roles in various physiological processes of plant life. In this study, a C3HC4-type zinc finger gene was isolated from Nicotiana benthamiana. Sequence analysis indicated that the gene encodes a 24-kDa protein with 191 amino acids containing one typical C3HC4-type zinc finger domain; this gene was named NbZFP1. Transient expression of pGDG-NbZFP1 demonstrated that NbZFP1 was localized to the chloroplast, especially in the chloroplasts of cells surrounding leaf stomata. Virus-induced gene silencing (VIGS) analysis indicated that silencing of NbZFP1 hampered fruit development, although the height of the plants was normal. An overexpression construct was then designed and transferred into Nicotiana benthamiana, and PCR and Southern blot showed that the NbZFP1 gene was successfully integrated into the Nicotiana benthamiana genome. The transgenic lines showed typical compactness, with a short internode length and sturdy stems. This is the first report describing the function of a C3HC4-type RING finger protein in tobacco. PMID:24901716

  2. Stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  3. [Chinese pine tree ring width chronology and its relations to climatic conditions in Qianshan Mountains].

    PubMed

    Chen, Zhen-Ju; Sun, Yu; He, Xing-Yuan; Chen, Wei; Shao, Xue-Mei; Zhang, Hua-Yu; Wang, Zhong-Yu; Liu, Xiao-Yu

    2007-10-01

    Taking Chinese pine in Qianshan Mountains as a sample, the tree ring width chronology including standard, residual, and Arstan chronologies was established. The results showed that the tree ring width of Chinese pine had a higher correlation with the temperature in May - July and in September - November, and significant positive correlations were observed between the tree ring width and the extreme minimum temperature in July and mean minimum temperature in September. The chronology had significant or very significant correlations with the extreme minimum temperature in December and next January, mean minimum temperature in January, annual precipitation, and the precipitation in April, May and last December. Chinese pine had stronger responses to the monthly/yearly water vapor pressure and relative humidity. The yearly and most monthly evaporation had negative effects on the growth, being most significant for the evaporation in April - July. The narrowed tree rings recorded by the chronology demonstrated the 30 times of extreme drought since 1 800. The growth of Chinese pine in Qianshan Mountains was also affected by the climate changes on global and hemisphere scales. There existed 11-, 23- and 50- year- common periodicity between the chronology and solar activity, and 10-, 20- and 45- year- common periodicity between the chronology and geomagnetic activity. PMID:18163297

  4. Actin Rings of Power.

    PubMed

    Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp

    2016-06-20

    Circular or ring-like actin structures play important roles in various developmental and physiological processes. Commonly, these rings are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger ring constriction. Actomyosin ring constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin ring-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin ring-like structures in various morphogenetic processes, shedding light on how those different rings have been adapted to fulfill their specific roles. PMID:27326928

  5. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    SciTech Connect

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  6. Dendrochronology and lakes: using tree-rings of alder to reconstruct lake levels

    NASA Astrophysics Data System (ADS)

    van der Maaten, Ernst; Buras, Allan; Scharnweber, Tobias; Simard, Sonia; Kaiser, Knut; Lorenz, Sebastian; van der Maaten-Theunissen, Marieke; Wilmking, Martin

    2014-05-01

    Climate change is considered a major threat for ecosystems around the world. Assessing its effects is challenging, amongst others, as we are unsure how ecosystems may respond to climate conditions they were not exposed to before. However, increased insight may be obtained by analyzing responses of ecosystems to past climate variability. In this respect, lake ecosystems appear as valuable sentinels, because they provide direct and indirect indicators of change through effects of climate. Lake-level fluctuations of closed catchments, for example, reflect a dynamic water balance, provide detailed insight in past moisture variations, and thereby allow for assessments of effects of anticipated climate change. Up to now, lake-level data are mostly obtained from gauging records and reconstructions from sediments and landforms. However, these records are in many cases only available over relatively short time periods, and, since geoscientific work is highly demanding, lake-level reconstructions are lacking for many regions. Here, we present and discuss an alternative method to reconstruct lake levels, which is based on tree-ring data of black alder (Alnus glutinosa L.). This tree species tolerates permanently waterlogged and temporally flooded conditions (i.e. riparian vegetation), and is often found along lakeshores. As the yearly growth of trees varies depending upon the experienced environmental conditions, annual rings of black alder from lakeshore vegetation likely capture information on variations in water table, and may therefore be used to reconstruct lake levels. Although alder is a relatively short-lived tree species, the frequent use of its' decay-resistant wood in foundations of historical buildings offers the possibility of extending living tree-chronologies back in time for several centuries. In this study, the potential to reconstruct lake-level fluctuations from tree-ring chronologies of black alder is explored for three lake ecosystems in the Mecklenburg

  7. Temperature signal instability of tree-ring δ13C chronology in the northeastern Qinghai-Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Wenzhi; Liu, Xiaohong; Xu, Guobao; Zeng, Xiaomin; Wu, Guoju; Zhang, Xuanwen; Qin, Dahe

    2016-04-01

    Tree ring δ13C as a climate proxy is widely used for palaeoclimate research, however, its temporal stability response to the climate change remains unclear under more than one limited factors on tree growth. Here, we used a millennium tree-ring δ13C chronology combining two annual-resolution δ13C chronologies since 1800 from long-lived Qilian juniper (Sabina przewalskii) to assess its instability of the climate signal in the northeastern Qinghai-Tibetan Plateau. Tree-ring δ13C chronologies were strongly correlated with the regional mean April to August temperature from 1956 to 2008, but the associations were absent within the period 1901 to 1955 values in the CRU TS dataset. Comparison of the millennium-long δ13C series with reconstructed Asian temperatures also demonstrated that the δ13C chronology exhibited climate signal temporal instability. Substantial oscillations were revealed using a frequency-dependent analysis and 51-year running correlation analysis from the millennium-long tree-ring δ13C and δ18O series. Dual-isotope approach indicated that stomatal limitations created a statistical significant positive correlation between tree-ring δ13C and δ18O, but photosynthetic rate may be dominant when the correlations were not significant. Our results suggest that tree-ring δ13C series in the northeastern Qinghai-Tibetan Plateau is responded instability to temperature variations in the past 1000 years.

  8. Annual growth and environmental relationships of the invasive species Sargassum muticum and Undaria pinnatifida in the lagoon of Venice

    NASA Astrophysics Data System (ADS)

    Sfriso, A.; Facca, C.

    2013-09-01

    The growth and autoecology of two alien invasive species: Sargassum muticum and Undaria pinnatifida spreading in the Venice Lagoon were studied monthly, during one year, in two sites of different depth. S. muticum was present year-round and reached its largest size (485 cm) and maximum growth (8.33 cm d-1) at the deepest station. U. pinnatifida was present only from November to May, reaching the highest size (130 cm) in March-April in the shallow station with growth peaks of 2.32 cm d-1. The growth of both species was mainly regulated by water temperature, nutrient concentration, especially nitrogen, and water turbidity. The study highlights the different ecological role already observed for the two species: U. pinnatifida prefers eutrophic areas and is not present along the sea-coastline. Its total standing crop does not exceed 0.2 ktonnes fwt for all the Venice Lagoon. Conversely, S. muticum colonizes areas with a lower eutrophication level, such as the lagoon inlets, reaching a total lagoon standing crop of 4-6 ktonnes fwt.

  9. EFFECT OF SOIL NITROGEN STRESS ON THE RELATIVE GROWTH RATE OF ANNUAL AND PERENNIAL GRASSES IN THE INTERMOUNTAIN WEST

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A trade-off between inherent relative growth rate (RGR) and tolerance to low nutrient availability is a central theory in plant ecology and is predicted to be a key factor influencing invasion resistance in nutrient-poor systems. Specifically, low nutrient conditions are predicted to favor native s...

  10. Multielemental analysis of tree rings: temporal accumulation patterns and relationships with air pollution

    SciTech Connect

    Baes, C.F. III; McLaughlin, S.B.

    1983-01-01

    Short-leaf pine (Pinus echinata) tree rings collected in East Tennessee showed steadily increasing concentrations of Al, Cd, Cu, Fe, Mn, Mo, Ti, and Zn over the past 20 to 25 years. In part, these increasing concentrations result from recent declines in tree growth rate, but when corrected for variations in growth rate, annual accumulations of many of these metals in xylem tissue has increased in recent years. The largest concentration increases with time were observed in rings from trees downwind of the 1200 MW(e) generating Kingston steam plant, which burns 4 x 10/sup 9/ kg coal per year. Trace metals concentrations in cambial tissues were found to be as high as ten times those in the most recently formed xylem, and concentrations of Al, Cd, Mn, and Zn are near levels that have been associated with toxic effects when found in above-ground tissues of herbaceous plants. In trees sampled in the Great Smoky Mountains National Park (GSMNP) there was a period of suppressed growth and increased iron concentration in rings formed between 1863 and 1912. During this time period 88 km upwind, smelting of iron and copper sulfide ores was occurring at the Copper Basin (Copperhill), near Ducktown, Tennessee. Associated with this smelting were large uncontrolled releases of SO/sub 2/ which killed all vegetation within 20 km of the Copper Basin. The patterns of growth suppression and iron accumulation observed in the GSMNP trees correspond remarkably well to the initiation of smelting operations in 1854, maximum uncontrolled SO/sub 2/ emissions in 1895, and the reduction in SO/sub 2/ emissions mandated by the US Supreme Court in 1908. This historical pattern and the widespread occurrence of similar patterns of growth suppression and increased iron concentrations in tree rings since the late 1950s provide strong inferential evidence of tree response to SO/sub 2/ deposition. 36 references, 3 figures, 1 table.

  11. From process to proxy: Ecological challenges and opportunities of tree-ring based environmental reconstructions

    NASA Astrophysics Data System (ADS)

    Wilmking, Martin; Buras, Allan; Heinrich, Ingo; Scharnweber, Tobias; Simard, Sonia; Smiljanic, Marko; van der Maaten, Ernst; van der Maaten-Theunissen, Marieke

    2014-05-01

    Trees are sessile, long-living organisms and as such constantly need to adapt to changing environmental conditions. Accordingly, they often show high phenotypic plasticity (the ability to change phenotypic traits, such as allocation of resources) in response to environmental change. This high phenotypic plasticity is generally considered as one of the main ingredients for a sessile organism to survive and reach high ages. Precisely because of the ability of trees to reach old age and their in-ability to simply run away when conditions get worse, growth information recorded in tree rings has long been used as a major environmental proxy, covering time scales from decades to millennia. Past environmental conditions (e.g. climate) are recorded in i.e. annual tree-ring width, early- and latewood width, wood density, isotopic concentrations, cell anatomy or wood chemistry. One prerequisite for a reconstruction is that the relationship between the environmental variable influencing tree growth and the tree-growth variable itself is stable through time. This, however, might contrast the ecological theory of high plasticity and the trees ability to adapt to change. To untangle possible mechanisms leading to stable or unstable relationships between tree growth and environmental variables, it is helpful to have exact site information and several proxy variables of each tree-ring series available. Although we gain insight into the environmental history of a sampling site when sampling today, this is extremely difficult when using archeological wood. In this latter case, we face the additional challenge of unknown origin, provenance and (or) site conditions, making it even more important to use multiple proxy time-series from the same sample. Here, we review typical examples, where the relationship between tree growth and environmental variables seems 1) stable and 2) instable through time, and relate these two cases to ecological theory. Based on ecological theory, we then

  12. Optimizing Thomson's jumping ring

    NASA Astrophysics Data System (ADS)

    Tjossem, Paul J. H.; Brost, Elizabeth C.

    2011-04-01

    The height to which rings will jump in a Thomson jumping ring apparatus is the central question posed by this popular lecture demonstration. We develop a simple time-averaged inductive-phase-lag model for the dependence of the jump height on the ring material, its mass, and temperature and apply it to measurements of the jump height for a set of rings made by slicing copper and aluminum alloy pipe into varying lengths. The data confirm a peak jump height that grows, narrows, and shifts to smaller optimal mass when the rings are cooled to 77 K. The model explains the ratio of the cooled/warm jump heights for a given ring, the reduction in optimal mass as the ring is cooled, and the shape of the mass resonance. The ring that jumps the highest is found to have a characteristic resistance equal to the inductive reactance of the set of rings.

  13. Reconstruction of historic fossil CO2 emissions using radiocarbonmeasurements from tree rings

    NASA Astrophysics Data System (ADS)

    Norris, M. W.; Turnbull, J. C.; Trimble, M.; Keller, E. D.; Baisden, W. T.; Renwick, J. A.

    2014-12-01

    This project aims to reconstruct historic fossil CO2 emissions from a point source. As a test case we use the Vector gas processing plant in Taranaki New Zealand which has emitted 0.1Tg C yr-1 (as CO2) since 1970. Previous work using air samples found 2-5 ppm mole fraction CO2ff 600m downwind of the plant; this study extends the data set back 30 years using radiocarbon measurements in tree rings. Trees incorporate CO2 from the local atmosphere into their cellulose which is laid down in annual growth rings during photosynthesis. To relate this to the fossil CO2 content of the air we measure 14C in annual tree rings at a local clean air site and compare this to measurements of 14C in the annual ring for the same year at our test site. Fossil CO2 is devoid of 14C so addition of CO2ff will cause an observed decrease in14C in samples directly related to the amount of CO2ff present. Trees growing immediately downwind of the Vector plant and from clean air locations in Taranaki and Wellington were cored. Annual rings were counted and cut into one year growth increments. Testing was performed on two cellulose extraction methods to confirm removal of contaminating material before the cellulose component was chemically isolated, combusted, graphitised and 14C measured by Accelerator Mass Spectrometry. We will present initial results of the data; showing that Wellington tree and Taranaki clean air trees compare well with the Wellington atmospheric record whereas trees growing downwind of the Vector plant demonstrate lower 14C content consistent with fossil CO2 addition. We compare historic CO2ff emissions as sampled by the trees with reported emissions from the Vector plant to quantify and evaluate the ability of the technique to monitor changes in fossil CO2 emissions. We demonstrate how this technique could be applied alongside complimentary methods to evaluate fossil CO2 emissions at point sources worldwide to determine compliance of CO2 emitters with emission reduction

  14. Jupiter's Main Ring/Ring Halo

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A mosaic of four images taken through the clear filter (610 nanometers) of the solid state imaging (CCD) system aboard NASA's Galileo spacecraft on November 8, 1996, at a resolution of approximately 46 kilometers (28.5 miles) per picture element (pixel) along Jupiter's rings. Because the spacecraft was only about 0.5 degrees above the ring plane, the image is highly foreshortened in the vertical direction. The images were obtained when Galileo was in Jupiter's shadow, peering back toward the Sun; the ring was approximately 2.3 million kilometers (1.4 million miles) away. The arc on the far right of the image is produced when sunlight is scattered by small particles comprising Jupiter's upper atmospheric haze. The ring also efficiently scatters light, indicating that much of its brightness is due to particles that are microns or less in diameter. Such small particles are believed to have human-scale lifetimes, i.e., very brief compared to the solar system's age.

    Jupiter's ring system is composed of three parts - - a flat main ring, a lenticular halo interior to the main ring, and the gossamer ring, outside the main ring. The near and far arms of Jupiter's main ring extend horizontally across the mosaic, joining together at the ring's ansa, on the figure's far left side. The near arm of the ring appears to be abruptly truncated close to the planet, at the point where it passes into Jupiter's shadow. Some radial structure is barely visible across the ring's ansa (top image). A faint mist of particles can be seen above and below the main rings. This vertically extended 'halo' is unusual in planetary rings, and is probably caused by electromagnetic forces pushing the smallest grains out of the ring plane. Because of shadowing, the halo is not visible close to Jupiter in the lower right part of the mosaic. To accentuate faint features in the bottom image of the ring halo, different brightnesses are shown through color. Brightest features are white or yellow and the

  15. On semi ring bornologies

    NASA Astrophysics Data System (ADS)

    Imran, A. N.; Rakhimov, I. S.; Husain, Sh. K. Said

    2016-06-01

    Our main focus in this work is to introduce new structure bornological semi rings. This generalizes the theory of algebraic semi rings from the algebraic setting to the framework of bornological sets. We give basic properties for this new structure. As well as, We study the fundamental construction of bornological semi ring as product, inductive limits and projective limits and their extensions on bornological semi ring. Additionally, we introduce the category of bornological semi rings and study product and pullback (fiber product) in the category of bornological semi rings.

  16. Lake Roosevelt Fisheries Evaluation Program; Movements and Growth of Marked Walleye Recaptured in Lake Roosevelt, 2000-2001 Annual Report.

    SciTech Connect

    McLellan, Holly; Scholz, Allan

    2002-03-01

    Walleye (Stizostedion vitreum) have been marked with floy tags in Lake Roosevelt since 1997 to estimate abundance, distribution and movement trends. In 2000, walleye were collected and marked during the spawning run in the Spokane River through electrofishing and angling to supplement movement and growth data collected in previous years. Walleye were also collected and marked during the 2000 and 2001 Kettle Falls Governor's Cup Walleye Tournaments. Seventy-six tag returns were recovered in 2000 and twenty-three in 2001. Walleye migrated into the Spokane River to spawn in mid April and early May. The majority of marked walleye were recovered within 25 km of their original marking location, with a few traveling long distances between recovery locations. Data also verified earlier results that walleye establish summer home ranges. Some walleye remained in the Spokane River, while others moved downstream, or upstream after entering the mainstem of Lake Roosevelt. Those moving upstream moved as far north as Keenlyside Dam in British Columbia (245 km). Growth data indicated similar trends exhibited in the past. Walleye growth and mortality rates were consistent with other walleye producing waters. Walleye condition was slightly below average when compared to other systems.

  17. Relation of Nickel Concentrations in Tree Rings to Groundwater Contamination

    NASA Astrophysics Data System (ADS)

    Yanosky, Thomas M.; Vroblesky, Don A.

    1992-08-01

    Increment cores were collected from trees growing at two sites where groundwater is contaminated by nickel. Proton-induced X ray emission spectroscopy was used to determine the nickel concentrations in selected individual rings and in parts of individual rings. Ring nickel concentrations were interpreted on the basis of recent concentrations of nickel in aquifers, historical information about site use activities, and model simulations of groundwater flow. Nickel concentrations in rings increased during years of site use but not in trees outside the contaminated aquifers. Consequently, it was concluded that trees may preserve in their rings an annual record of nickel contamination in groundwater. Tulip trees and oaks contained higher concentrations of nickel than did sassafras, sweet gum, or black cherry. No evidence was found that nickel accumulates consistently within parts of individual rings or that nickel is translocated across ring boundaries.

  18. Oxygen Isotopes in Tree Rings: A 345 Year Record of Precipitation in Amazonia

    NASA Astrophysics Data System (ADS)

    Jenkins, H. S.; Baker, P. A.; Evans, M. N.

    2008-12-01

    The Amazon basin is one of the world's key centers of atmospheric convection and acts as an engine for global hydrologic circulation. Despite its importance, a paucity of high resolution climate data exists for this region, in large part due to a poor instrumental record. The oxygen isotopic measurement of meteoric water has been used extensively to reconstruct past temperatures derived from ice cores, corals, and tree rings but is only recently recognized as a precipitation proxy in the tropics. Here we present a continuous, highly resolved (intra-annual), 345 year oxygen isotopic record from the Madre de Dios department in Southeastern Peru. Using tropical hardwood species Dipteryx micrantha, we present oxygen (and carbon) isotopic data from digested tree ring cellulose. We also present some of the first intra-annual (early wood versus late wood) isotopic data on this old growth tropical species. We demonstrate the utility of Amazon tropical tree rings to accurately record rainfall. We also identify that this meteoric water was delivered to the region via the South American Low-level Jet (SALLJ), which develops over the Atlantic and is the major water source during the South American Summer Monsoon.

  19. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings. PMID:16601188

  20. Saturn's F-Ring

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 6.9 million km from Saturn on 8 November 1980. The brightness variations of this tightly-constrained ring shown here indicate that the ring is less uniform in makeup than the larger rings. JPL managed the Voyager Project for NASA's Office of Space Science

  1. Neptune - full ring system

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This pair of Voyager 2 images (FDS 11446.21 and 11448.10), two 591-s exposures obtained through the clear filter of the wide angle camera, show the full ring system with the highest sensitivity. Visible in this figure are the bright, narrow N53 and N63 rings, the diffuse N42 ring, and (faintly) the plateau outside of the N53 ring (with its slight brightening near 57,500 km).

  2. Growth

    NASA Astrophysics Data System (ADS)

    Waag, Andreas

    This chapter is devoted to the growth of ZnO. It starts with various techniques to grow bulk samples and presents in some detail the growth of epitaxial layers by metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and pulsed laser deposition (PLD). The last section is devoted to the growth of nanorods. Some properties of the resulting samples are also presented. If a comparison between GaN and ZnO is made, very often the huge variety of different growth techniques available to fabricate ZnO is said to be an advantage of this material system. Indeed, growth techniques range from low cost wet chemical growth at almost room temperature to high quality MOCVD growth at temperatures above 1, 000∘C. In most cases, there is a very strong tendency of c-axis oriented growth, with a much higher growth rate in c-direction as compared to other crystal directions. This often leads to columnar structures, even at relatively low temperatures. However, it is, in general, not straight forward to fabricate smooth ZnO thin films with flat surfaces. Another advantage of a potential ZnO technology is said to be the possibility to grow thin films homoepitaxially on ZnO substrates. ZnO substrates are mostly fabricated by vapor phase transport (VPT) or hydrothermal growth. These techniques are enabling high volume manufacturing at reasonable cost, at least in principle. The availability of homoepitaxial substrates should be beneficial to the development of ZnO technology and devices and is in contrast to the situation of GaN. However, even though a number of companies are developing ZnO substrates, only recently good quality substrates have been demonstrated. However, these substrates are not yet widely available. Still, the situation concerning ZnO substrates seems to be far from low-cost, high-volume production. The fabrication of dense, single crystal thin films is, in general, surprisingly difficult, even when ZnO is grown on a ZnO substrate. However

  3. Growth habit and leaf economics determine gas exchange responses to high elevation in an evergreen tree, a deciduous shrub and a herbaceous annual

    PubMed Central

    Shi, Zuomin; Haworth, Matthew; Feng, Qiuhong; Cheng, Ruimei; Centritto, Mauro

    2015-01-01

    Plant growth at high elevations necessitates physiological and morphological plasticity to enable photosynthesis (A) under conditions of reduced temperature, increased radiation and the lower partial pressure of atmospheric gases, in particular carbon dioxide (pCO2). Previous studies have observed a wide range of responses to elevation in plant species depending on their adaptation to temperature, elevational range and growth habit. Here, we investigated the effect of an increase in elevation from 2500 to 3500 m above sea level (a.s.l.) on three montane species with contrasting growth habits and leaf economic strategies. While all of the species showed identical increases in foliar δ13C, dark respiration and nitrogen concentration with elevation, contrasting leaf gas exchange and photosynthetic responses were observed between species with different leaf economic strategies. The deciduous shrub Salix atopantha and annual herb Rumex dentatus exhibited increased stomatal (Gs) and mesophyll (Gm) conductance and enhanced photosynthetic capacity at the higher elevation. However, evergreen Quercus spinosa displayed reduced conductance to CO2 that coincided with lower levels of photosynthetic carbon fixation at 3500 m a.s.l. The lower Gs and Gm values of evergreen species at higher elevations currently constrains their rates of A. Future rises in the atmospheric concentration of CO2 ([CO2]) will likely predominantly affect evergreen species with lower specific leaf areas (SLAs) and levels of Gm rather than deciduous species with higher SLA and Gm values. We argue that climate change may affect plant species that compose high-elevation ecosystems differently depending on phenotypic plasticity and adaptive traits affecting leaf economics, as rising [CO2] is likely to benefit evergreen species with thick sclerophyllous leaves. PMID:26433706

  4. Growth habit and leaf economics determine gas exchange responses to high elevation in an evergreen tree, a deciduous shrub and a herbaceous annual.

    PubMed

    Shi, Zuomin; Haworth, Matthew; Feng, Qiuhong; Cheng, Ruimei; Centritto, Mauro

    2015-01-01

    Plant growth at high elevations necessitates physiological and morphological plasticity to enable photosynthesis (A) under conditions of reduced temperature, increased radiation and the lower partial pressure of atmospheric gases, in particular carbon dioxide (pCO2). Previous studies have observed a wide range of responses to elevation in plant species depending on their adaptation to temperature, elevational range and growth habit. Here, we investigated the effect of an increase in elevation from 2500 to 3500 m above sea level (a.s.l.) on three montane species with contrasting growth habits and leaf economic strategies. While all of the species showed identical increases in foliar δ(13)C, dark respiration and nitrogen concentration with elevation, contrasting leaf gas exchange and photosynthetic responses were observed between species with different leaf economic strategies. The deciduous shrub Salix atopantha and annual herb Rumex dentatus exhibited increased stomatal (Gs) and mesophyll (Gm) conductance and enhanced photosynthetic capacity at the higher elevation. However, evergreen Quercus spinosa displayed reduced conductance to CO2 that coincided with lower levels of photosynthetic carbon fixation at 3500 m a.s.l. The lower Gs and Gm values of evergreen species at higher elevations currently constrains their rates of A. Future rises in the atmospheric concentration of CO2 ([CO2]) will likely predominantly affect evergreen species with lower specific leaf areas (SLAs) and levels of Gm rather than deciduous species with higher SLA and Gm values. We argue that climate change may affect plant species that compose high-elevation ecosystems differently depending on phenotypic plasticity and adaptive traits affecting leaf economics, as rising [CO2] is likely to benefit evergreen species with thick sclerophyllous leaves. PMID:26433706

  5. Ultra-high Resolution Carbon Isotope Records in Tree Rings: Indicators of Carbon Allocation and Growing Season Precipitation/Temperature (Invited)

    NASA Astrophysics Data System (ADS)

    Jahren, A.; Schubert, B.

    2010-12-01

    The rapidity and ease of carbon stable isotope measurements on organic substrates has opened the possibility of ultra-high resolution δ13C analyses within tree rings at < 30 to 100 micron increments. We present such measurements for 80 individual tree rings, from 10 trees spanning the last 55 million years in age from arctic, temperate, and tropical environments. Morphological features such as growth rings and resin canals were not preserved in some ancient specimens making identification of annual rings via standard techniques impossible. However, the annual patterns observed in ultra-high resolution δ13C records allowed for characterization of these unknown specimens as evergreen or deciduous. A combination of our data with that published in the literature showed a strong correlation between the amplitude of the δ13C pattern and growing season precipitation/temperature in > 90% of modern evergreen trees examined to date. Ultra-high resolution δ13C analyses of ancient, non-permineralized, evergreen trees could therefore provide quantitative estimates of past climate at annual or seasonal resolution.

  6. The Jumping Ring Experiment

    ERIC Educational Resources Information Center

    Baylie, M.; Ford, P. J.; Mathlin, G. P.; Palmer, C.

    2009-01-01

    The jumping ring experiment has become central to liquid nitrogen shows given as part of the outreach and open day activities carried out within the University of Bath. The basic principles of the experiment are described as well as the effect of changing the geometry of the rings and their metallurgical state. In general, aluminium rings are…

  7. Saturn's F-Ring

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 0.75 million km from Saturn on 12 November 1980. The kinks and braids of this tightly-constrained ring are visible along with the outer edge of the A Ring. JPL managed the Voyager Project for NASA's Office of Space Science.

  8. Rings Around Uranus

    ERIC Educational Resources Information Center

    Maran, Stephen P.

    1977-01-01

    Events leading up to the discovery of the rings of Uranus are described. The methods used and the logic behind the methods are explained. Data collected to prove the existence of the rings are outlined and theories concerning the presence of planetary rings are presented. (AJ)

  9. Tree ring anatomical variability as an indicator for large-magnitude spring flooding in the Lower Mississippi Basin

    NASA Astrophysics Data System (ADS)

    Therrell, M. D.; Meko, M. D.; Bialecki, M.; Harley, G. L.

    2015-12-01

    Predicting the magnitude and frequency of floods relies on instrumental measurements of flood stage and discharge, however instrumental observations prior to the late-nineteenth century are rare. Using paleoproxies such as tree rings to study floods that occurred before the instrumental record, can help provide context for the modern flood record especially the variability of flood recurrence patterns. Riparian trees growing on flooded sites often record flood events as inter- and intra-annual variability in size, shape and arrangement of vessels in the annual xylem growth increment. In this study, we used anomalous anatomical features as well as a modified measure of earlywood (EW) vessel width of oak (Quercus sp.) annual tree rings to identify large-magnitude spring-season flood events at three locations in the Lower Mississippi River (LMR) basin for the past ~300 years. We compared the flood-ring anomaly and EW chronologies with daily river stage height data at several locations and these comparisons indicate that our new flood ring records can individually and jointly explain significant amounts of the variance in both stage height and number of days in flood during spring flood events. Our analyses indicate that our chronologies are recording nearly all large observed LMR floods in the 20th century, and provide a new record of similar events in the 18th and 19th centuries. These results suggest that tree-rings can be effectively used to develop and improve pre-instrumental flood records throughout the LMW region and potentially other similar systems.

  10. Measuring tree-ring increments on tree bole sections with a video-based robotic positioner.

    PubMed

    Schmidt, R A; Kaufmann, M R; Porth, L; Watkins, R K

    1996-10-01

    We report on the design and performance of a system that speeds measurement of radial tree-ring increments on tree stem disks; this method replaces the usual binocular microscope with a video image, and automates the measuring and recording processes. The system was used to measure bole sections cut from stems at various heights to determine volume growth of representative trees in an old-growth ponderosa pine stand. The objective of the measurement system was to speed acquisition of annual growth increments from a large number of disks. A personal computer controls the location of a video camera in a 3-axis positioning system. The operator views the sample on a video monitor and positions the camera over each ring by selecting it with a computer-driven mouse. The computer measures and records the distance that the camera moves between each ring. Task selection is facilitated by menu-driven software that also formats, checks and organizes data files. Measurements have a resolution of 0.026 mm; however, finer resolution could be obtained with a different camera lens. Tests of measurement variability (repeated measurements by individual operators on a single radius) indicated standard errors of 0.006 mm or less for the first measurement sets for four operators. Correlation coefficients among four radii per bole section were as low as 0.66 for a whole tree, suggesting that measurements on single radii may provide poor estimates of radial growth for old trees. This system also offers the potential for automatic ring detection and measurement. PMID:14871678