Sample records for globularis nitella flexilis

  1. Distribution, morphological variability, ecology and the present state of Nitella from Lake Ohrid and its surroundings

    Trajanovska Sonja


    Full Text Available Our research into 52 profiles of the littoral zone of the Macedonian part of Lake Ohrid and numerous samples taken from its surroundings has resulted in a detailed picture of the composition of the Charophyta vegetation in the lake. The results of the research also include data regarding the species composition and present state of Nitella. The dominant species of Nitella is Nitella opaca, which is characterized by a specific distribution, morphological variability and ecology. The present state of Nitella is not steady, especially in the watershed of the lake, since in this area there are some permanent changes in the hydrology of the terrain. Therefore, there is a need to establish long-term and complex monitoring which will result in the prompt detection of risk factors and influences, thereby enabling a rapid reaction to a possible newly emerged negative state.

  2. Cellulose synthesis inhibition, cell expansion, and patterns of cell wall deposition in Nitella internodes

    Richmond, P.A.; Metraux, J.P.


    The authors have investigated the pattern of wall deposition and maturation and correlated it with cell expansion and cellulose biosynthesis. The herbicide 2,6-dichlorobenzonitrile (DCB) was found to be a potent inhibitor of cellulose synthesis, but not of cell expansion in Nitella internodal cells. Although cellulose synthesis is inhibited during DCB treatment, matrix substances continue to be synthesized and deposited. The inhibition of cellulose microfibril deposition can be demonstrated by various techniques. These results demonstrate that matrix deposition is by apposition, not by intussusception, and that the previously deposited wall moves progressively outward while stretching and thinning as a result of cell expansion

  3. Diffusive Promotion by Velocity Gradient of Cytoplasmic Streaming (CPS in Nitella Internodal Cells.

    Kenji Kikuchi

    Full Text Available Cytoplasmic streaming (CPS is well known to assist the movement of nutrients, organelles and genetic material by transporting all of the cytoplasmic contents of a cell. CPS is generated by motility organelles that are driven by motor proteins near a membrane surface, where the CPS has been found to have a flat velocity profile in the flow field according to the sliding theory. There is a consistent mixing of contents inside the cell by CPS if the velocity gradient profile is flattened, which is not assisted by advection diffusion but is only supported by Brownian diffusion. Although the precise flow structure of the cytoplasm has an important role for cellular metabolism, the hydrodynamic mechanism of its convection has not been clarified. We conducted an experiment to visualise the flow of cytoplasm in Nitella cells by injecting tracer fluorescent nanoparticles and using a flow visualisation system in order to understand how the flow profile affects their metabolic system. We determined that the velocity field in the cytosol has an obvious velocity gradient, not a flattened gradient, which suggests that the gradient assists cytosolic mixing by Taylor-Aris dispersion more than by Brownian diffusion.

  4. Resistance to white pine blister rust in Pinus flexilis and P

    Anna W. Schoettle; Richard A. Sniezko; Angelia Kegley; Jerry Hill; Kelly S. Burns


    The non-native fungus Cronartium ribicola, that causes white pine blister rust (WPBR), is impacting or threatening limber pine, Pinus flexilis, and Rocky Mountain bristlecone pine, Pinus aristata. In the Southern Rockies, where the rust invasion is still expanding, we have the opportunity to be proactive and prepare the landscape for invasion. Genetic...

  5. Regeneration of Rocky Mountain bristlecone pine (Pinus aristata) and limber pine (Pinus flexilis) three decades after stand-replacing fires

    Jonathan D. Coop; Anna W. Schoettle


    Rocky Mountain bristlecone pine (Pinus aristata) and limber pine (Pinus flexilis) are important highelevation pines of the southern Rockies that are forecast to decline due to the recent spread of white pine blister rust (Cronartium ribicola) into this region. Proactive management strategies to promote the evolution of rust resistance and maintain ecosystem function...

  6. The plastid genome of Najas flexilis: adaptation to submersed environments is accompanied by the complete loss of the NDH complex in an aquatic angiosperm.

    Elena L Peredo

    Full Text Available The re-colonization of aquatic habitats by angiosperms has presented a difficult challenge to plants whose long evolutionary history primarily reflects adaptations to terrestrial conditions. Many aquatics must complete vital stages of their life cycle on the water surface by means of floating or emergent leaves and flowers. Only a few species, mainly within the order Alismatales, are able to complete all aspects of their life cycle including pollination, entirely underwater. Water-pollinated Alismatales include seagrasses and water nymphs (Najas, the latter being the only freshwater genus in the family Hydrocharitaceae with subsurface water-pollination. We have determined the complete nucleotide sequence of the plastid genome of Najas flexilis. The plastid genome of N. flexilis is a circular AT-rich DNA molecule of 156 kb, which displays a quadripartite structure with two inverted repeats (IR separating the large single copy (LSC from the small single copy (SSC regions. In N. flexilis, as in other Alismatales, the rps19 and trnH genes are localized in the LSC region instead of within the IR regions as in other monocots. However, the N. flexilis plastid genome presents some anomalous modifications. The size of the SSC region is only one third of that reported for closely related species. The number of genes in the plastid is considerably less. Both features are due to loss of the eleven ndh genes in the Najas flexilis plastid. In angiosperms, the absence of ndh genes has been related mainly to the loss of photosynthetic function in parasitic plants. The ndh genes encode the NAD(PH dehydrogenase complex, believed essential in terrestrial environments, where it increases photosynthetic efficiency in variable light intensities. The modified structure of the N. flexilis plastid genome suggests that adaptation to submersed environments, where light is scarce, has involved the loss of the NDH complex in at least some photosynthetic angiosperms.

  7. Linking carbon and water limitations to drought-induced mortality of Pinus flexilis seedlings

    Reinhardt, Keith; Germino, Matthew J.; Kueppers, Lara M.; Domec, Jean-Christophe; Mitton, Jeffry


    Survival of tree seedlings at high elevations has been shown to be limited by thermal constraints on carbon balance, but it is unknown if carbon relations also limit seedling survival at lower elevations, where water relations may be more important. We measured and modeled carbon fluxes and water relations in first-year Pinus flexilis seedlings in garden plots just beyond the warm edge of their natural range, and compared these with dry-mass gain and survival across two summers. We hypothesized that mortality in these seedlings would be associated with declines in water relations, more so than with carbon-balance limitations. Rather than gradual declines in survivorship across growing seasons, we observed sharp, large-scale mortality episodes that occurred once volumetric soil-moisture content dropped below 10%. By this point, seedling water potentials had decreased below −5 MPa, seedling hydraulic conductivity had decreased by 90% and seedling hydraulic resistance had increased by >900%. Additionally, non-structural carbohydrates accumulated in aboveground tissues at the end of both summers, suggesting impairments in phloem-transport from needles to roots. This resulted in low carbohydrate concentrations in roots, which likely impaired root growth and water uptake at the time of critically low soil moisture. While photosynthesis and respiration on a leaf area basis remained high until critical hydraulic thresholds were exceeded, modeled seedling gross primary productivity declined steadily throughout the summers. At the time of mortality, modeled productivity was insufficient to support seedling biomass-gain rates, metabolism and secondary costs. Thus the large-scale mortality events that we observed near the end of each summer were most directly linked with acute, episodic declines in plant hydraulic function that were linked with important changes in whole-seedling carbon relations.

  8. Linking carbon and water relations to drought-induced mortality in Pinus flexilis seedlings.

    Reinhardt, Keith; Germino, Matthew J; Kueppers, Lara M; Domec, Jean-Christophe; Mitton, Jeffry


    Survival of tree seedlings at high elevations has been shown to be limited by thermal constraints on carbon balance, but it is unknown if carbon relations also limit seedling survival at lower elevations, where water relations may be more important. We measured and modeled carbon fluxes and water relations in first-year Pinus flexilis seedlings in garden plots just beyond the warm edge of their natural range, and compared these with dry-mass gain and survival across two summers. We hypothesized that mortality in these seedlings would be associated with declines in water relations, more so than with carbon-balance limitations. Rather than gradual declines in survivorship across growing seasons, we observed sharp, large-scale mortality episodes that occurred once volumetric soil-moisture content dropped below 10%. By this point, seedling water potentials had decreased below -5 MPa, seedling hydraulic conductivity had decreased by 90% and seedling hydraulic resistance had increased by >900%. Additionally, non-structural carbohydrates accumulated in aboveground tissues at the end of both summers, suggesting impairments in phloem-transport from needles to roots. This resulted in low carbohydrate concentrations in roots, which likely impaired root growth and water uptake at the time of critically low soil moisture. While photosynthesis and respiration on a leaf area basis remained high until critical hydraulic thresholds were exceeded, modeled seedling gross primary productivity declined steadily throughout the summers. At the time of mortality, modeled productivity was insufficient to support seedling biomass-gain rates, metabolism and secondary costs. Thus the large-scale mortality events that we observed near the end of each summer were most directly linked with acute, episodic declines in plant hydraulic function that were linked with important changes in whole-seedling carbon relations. © The Author 2015. Published by Oxford University Press. All rights reserved

  9. Changes in whole-tree water relations during ontogeny of Pinus flexilis and Pinus ponderosa in a high-elevation meadow.

    Fischer, Dylan G; Kolb, Thomas E; DeWald, Laura E


    We measured sap flux in Pinus ponderosa Laws. and Pinus flexilis James trees in a high-elevation meadow in northern Arizona that has been invaded by conifers over the last 150 years. Sap flux and environmental data were collected from July 1 to September 1, 2000, and used to estimate leaf specific transpiration rate (El), canopy conductance (Gc) and whole-plant hydraulic conductance (Kh). Leaf area to sapwood area ratio (LA/SA) increased with increasing tree size in P. flexilis, but decreased with increasing tree size in P. ponderosa. Both Gc and Kh decreased with increasing tree size in P. flexilis, and showed no clear trends with tree size in P. ponderosa. For both species, Gc was lower in the summer dry season than in the summer rainy season, but El did not change between wet and dry summer seasons. Midday water potential (Psi(mid)) did not change across seasons for either species, whereas predawn water potential (Psi(pre)) tracked variation in soil water content across seasons. Pinus flexilis showed greater stomatal response to vapor pressure deficit (VPD) and maintained higher Psi(mid) than P. ponderosa. Both species showed greater sensitivity to VPD at high photosynthetically active radiation (PAR; > 2500 micromol m-2 s-1) than at low PAR (Pinus species, and was influenced by changes in LA/SA. Whole-tree water use and El were similar between wet and dry summer seasons, possibly because of tight stomatal control over water loss. 2002 Heron Publishing--Victoria, Canada

  10. First report of the white pine blister rust fungus, Cronartium ribicola, infecting Pinus flexilis on Pine Mountain, Humboldt National Forest, Elko County, northeastern Nevada, U.S.A.

    Detlev R. Vogler; Patricia E. Maloney; Tom Burt; Jacob W. Snelling


    In 2013, while surveying for five-needle white pine cone crops in northeastern Nevada, we observed white pine blister rust, caused by the rust pathogen Cronartium ribicola Fisch., infecting branches and stems of limber pines (Pinus flexilis James) on Pine Mountain (41.76975°N, 115.61622°W), Humboldt National Forest,...

  11. Effects of Pinus flexilis on the dynamics and structure of plant communities on the northern Rocky Mountain front, and, Training biologists for emerging niches in non-traditional jobs

    Baumeister, Dayna Marie

    My research examines the relative importance of interacting mechanisms (amelioration of wind, provision of shade, accumulation of snow pack, and alteration of soil characteristics) governing facilitation between Pinus flexilis and two understory species, Pseudotsuga menziesii and Ribes cereum in Montana. Survival of understory species was greatest beneath P. flexilis at a leeward site (Pseudotsuga, 38% and Ribes, 63%), and lowest in the open at a windward site (2% and 6%, respectively). The effects of wind amelioration, shade provision, and snowdrift accumulation were separated experimentally and after two years, shade was of overwhelming importance for the survival of both species. Once shade was provided, effects of wind amelioration and increased snow pack increased survival, suggesting a hierarchical functioning of mechanisms. High winter mortality of Pseudotsuga suggests P. flexilis canopies may prevent photoinhibition and winter desiccation through reduction of light and insulation from variable temperatures. High summer mortality of Ribes suggests P. flexilis canopies may reduce transpiration through lowering leaf temperatures, thereby decreasing vapor pressure deficits. In this system, several mechanisms governing facilitation operated simultaneously, but in a hierarchical manner of relative importance thereby determining the overall effect of P. flexilis on understory plants. I also studied facilitation and secondary succession by examining understory species composition beneath individual P. flexilis and in P. flexilis stands. As P. flexilis trees and stands aged, understory species richness increased, as did cover of forbs and shrubs, but cover of grasses decreased. Stands currently dominated by P. flexilis are shifting towards dominance by Pseudotsuga primarily in mesic sites, with corresponding increases in litter and shrub cover and decreases in grasses and P. flexilis recruitment. Since the 1860's succession from grasslands to forest on the Front has

  12. Trends in stomatal density and 13C/12C ratios of Pinus flexilis needles during last glacial-interglacial cycle

    Van de Water, P.K.; Leavitt, S.W.; Betancourt, J.L.


    Measurements of stomatal density and delta 13C of limber pine (Pinus flexilis) needles (leaves) preserved in pack rat middens from the Great Basin reveal shifts in plant physiology and leaf morphology during the last 30,000 years. Sites were selected so as to offset glacia to Holocene climatic differences and thus to isolate the effects of changing atmospheric CO2 levels. Stomatal density decreased approximately 17 percent and delta 13C decreased approximately 1.5 per ml during deglaciation from 15,000 to 12,000 years ago, concomitant with a 30 percent increase in atmospheric CO2. Water-use efficiency increased approximately 15 percent during deglaciation, if temperature and humidity were held constant and the proxy values for CO2 and delta 13C of past atmospheres are accurate. The delta 13C variations may help constrain hypotheses about the redistribution of carbon between the atmosphere and biosphere during the last glacial-interglacial cycle

  13. The role of hybridization during ecological divergence of southwestern white pine (Pinus strobiformis) and limber pine (P. flexilis).

    Menon, Mitra; Bagley, Justin C; Friedline, Christopher J; Whipple, Amy V; Schoettle, Anna W; Leal-Sàenz, Alejandro; Wehenkel, Christian; Molina-Freaner, Francisco; Flores-Rentería, Lluvia; Gonzalez-Elizondo, M Socorro; Sniezko, Richard A; Cushman, Samuel A; Waring, Kristen M; Eckert, Andrew J


    Interactions between extrinsic factors, such as disruptive selection and intrinsic factors, such as genetic incompatibilities among loci, often contribute to the maintenance of species boundaries. The relative roles of these factors in the establishment of reproductive isolation can be examined using species pairs characterized by gene flow throughout their divergence history. We investigated the process of speciation and the maintenance of species boundaries between Pinus strobiformis and Pinus flexilis. Utilizing ecological niche modelling, demographic modelling and genomic cline analyses, we illustrated a divergence history with continuous gene flow. Our results supported an abundance of advanced generation hybrids and a lack of loci exhibiting steep transition in allele frequency across the hybrid zone. Additionally, we found evidence for climate-associated variation in the hybrid index and niche divergence between parental species and the hybrid zone. These results are consistent with extrinsic factors, such as climate, being an important isolating mechanism. A build-up of intrinsic incompatibilities and of coadapted gene complexes is also apparent, although these appear to be in the earliest stages of development. This supports previous work in coniferous species demonstrating the importance of extrinsic factors in facilitating speciation. Overall, our findings lend support to the hypothesis that varying strength and direction of selection pressures across the long lifespans of conifers, in combination with their other life history traits, delays the evolution of strong intrinsic incompatibilities. © 2018 John Wiley & Sons Ltd.

  14. Temporal variation of Nitella furcata subsp. mucronata var. mucronata f. oligospira (Charophyceae in the Ninféias pond, São Paulo State, southeast Brazil Variação temporal de Nitella furcata subsp. mucronata var. mucronata f. oligospira (Charophyceae no Lago das Ninféias, São Paulo, sudeste do Brasil

    Norma Catarina Bueno


    Full Text Available Temporal and spatial variation of Nitella furcata (Roxburgh ex Bruzelius C. Agardh emend. R.D. Wood subsp. mucronata (A. Braun R.D. Wood var. mucronata f. oligospira (A. Braun R.D. Wood were studied at the Ninféias pond (23°38'18.9"S, 46°37'16.3"W, a tropical, shallow, mesotrophic reservoir located in the Parque Estadual das Fontes do Ipiranga Biological Reserve, Municipality of São Paulo, southeast Brazil. Water samples were collected monthly from October/1996 to October/1997 for turbidity, electric conductivity, pH, alkalinity, dissolved oxygen, nutrients, biomass, and algal phenology analysis. Spatial distribution pattern of algal biomass showed that all four sampling stations were similar among themselves during the whole study period. Regarding the temporal variation, greatest algal total biomass values (98.35-266.06 g.m-2 were measured during the rainy period whereas the smallest ones (48.86-170.56 g.m-2 were detected during the dry period. Algal population density peaked at all four sampling stations from October/1996 to April/1997 (rainy period when the greatest values of air and water temperature, precipitation, solar radiation, turbidity, total nitrogen, and ammonium were measured allowing favorable conditions for the algal growth. Period from May/1997 (late fall to October/1997 (early spring was favorable to the development of reproductive structures (nucules and globules with consequent decrease of algal biomass and population density, clearly suggesting the greatest energy allocation towards the development of sexual reproductive structures. This fact was confirmed by the canonic correspondence analysis that indicated strong correlation between nucules length and width, number of nucules per plant, and oospores length and width with the low values of pH and high ones of dissolved inorganic matter detected during the dry period. Consequently, environmental factors such as increasing of water temperature and nutrients availability

  15. Warming and the dependence of limber pine (Pinus flexilis) establishment on summer soil moisture within and above its current elevation range

    Moyes, Andrew B.; Castanha, Cristina; Germino, Matthew J.; Kueppers, Lara M.


    Continued changes in climate are projected to alter the geographic distributions of plant species, in part by affecting where individuals can establish from seed. We tested the hypothesis that warming promotes uphill redistribution of subalpine tree populations by reducing cold limitation at high elevation and enhancing drought stress at low elevation. We seeded limber pine (Pinus flexilis) into plots with combinations of infrared heating and water addition treatments, at sites positioned in lower subalpine forest, the treeline ecotone, and alpine tundra. In 2010, first-year seedlings were assessed for physiological performance and survival over the snow-free growing season. Seedlings emerged in midsummer, about 5–8 weeks after snowmelt. Low temperature was not observed to limit seedling photosynthesis or respiration between emergence and October, and thus experimental warming did not appear to reduce cold limitation at high elevation. Instead, gas exchange and water potential from all sites indicated a prevailing effect of summer moisture stress on photosynthesis and carbon balance. Infrared heaters raised soil growing degree days (base 5 °C, p p 3 m-3 consistently corresponded with moderate and severe indications of drought stress in midday stem water potential, stomatal conductance, photosynthesis, and respiration. Seedling survival was greater in watered plots than in heated plots (p = 0.01), and negatively related to soil growing degree days and duration of exposure to θ 3 m-3 in a stepwise linear regression model (p seasonal moisture stress and high soil surface temperature imposed a strong limitation to limber pine seedling establishment across a broad elevation gradient, including at treeline, and that these limitations are likely to be enhanced by further climate warming.

  16. Difference in optimum temperature for growth and reproduction in benthic foraminifer Rosalina globularis: Implications for paleoclimatic studies

    Saraswat, R.; Nigam, R.; Pachkhande, S.

    , P.A., Gabriel, J.J. 2010. Linkages between Holocene paleoclimate and paleohydrogeology preserved in a Yucatan underwater cave. Quat. Sci. Rev. 29, 2788-2798. 9 Leorri, E., Martin, R., McLaughlin, P. 2006. Holocene environmental and parasequence...

  17. Charophytes of the lake Garda (Northern Italy: a preliminary assessment of diversity and distribution

    Rossano Bolpagni


    Full Text Available Charophytes (stoneworts and bassweeds are a typical macrophytic component of inland water ecosystems. Well-developed submerged meadows of charophytes are expression of clear water and rather low phytoplankton concentrations. Consequently, among aquatic macroscopic primary producers, charophytes are one of the most threatened groups being very sensitive to phosphorous availability, turbidity and water level perturbations. Accordingly, charophytes have been suffering a massive diversity loss worldwide over the last century, mainly because of human-induced pressures. During summer 2011, detailed field surveys were carried out with the main purpose of filling knowledge gaps concerning aquatic flora and vegetation of the lake Garda – the largest lake in Italy and one of the deepest in Europe. Along randomly selected transects, floristic data were collected following standard procedures, as imposed by the Water Framework Directive. Overall, 12 different species of charophytes were recorded, which accounts for 36% of total Italian charophytes and 19% of European species. The most diffuse species were Chara globularis and C. intermedia; whereas, the most interesting taxa were Chara polyacantha and Nitella hyalina, two species with narrow distribution in Italy. Overall in the lake Garda, dense stands of charophytes covered almost homogeneously the littoral sectors at a water depth between 3 and 12 m. The deepest species was C. globularis, which reached a maximum depth of colonisation of about 17.5 m. Charophytes represent a major element among the primary producers in the lake Garda. The high local charophyte diversity and the rather wide most colonised areas (~1000-1200 ha confirm that the lake Garda is an important reserve for many rare and threatened charophytes. For the first time, these results highlight the key role of the lake Garda for charophyte diversity at a national and European level.

  18. Las macrófitas de algunos lagos alto-andinos del Ecuador y su bajo potencial como bioindicadores de eutrofización

    Benjamin Kiersch


    Full Text Available Se estudió la presencia de macrófitas en tres lagos de altoandinos en Ecuador,Lago San Pablo,Laguna La Mica y Lago Cuicocha.Los primeros dos son eutróficos, mientras que el último es un lago de caldera extremadamente oligotrófico.Las especies dominantes en los lagos eutróficos son:Ceratophyllum demersum , Myriophyllum quitense ,Potamogeton illinoensis ,P. striatus y Elodea matthewsii .En el lago oligotrófico están presentes P.pectinatus,P.illinoensi s,y las Characeae Chara rusbyabana ,Ch.globularis y Nitella acuminata .La máxima profundidad para la presencia de macrófitas puede ser usada como un indicador del estado de eutroficación,la cual va desde 5 m en la Laguna Mica a 35 m en el Lago Cuicocha.El valor de la bioindicación de las especies de macrófitas en estos lagos altoandinos es bajo,debido a que solo unas pocas especies están presentes,y algunas de ellas no son específicas para las condiciones ambientales.Macrophytes from some high Andean lakes of Ecuador and their low potential as bioindicators of eutrophication .The occurrence of macrophyte in three high Andean lakes of Ecuador,Lago San Pablo, Laguna La Mica and Lago Cuicocha was recorded in 5-9 transects per lake.The first two lakes are eutrophic, the third is an extremely oligotrophic caldera lake.The dominant species in eutrophic lakes are Ceratophyllum demersum ,Myriophyllum quitense ,Potamogeton illinoensis ,P.striatus and Elodea matthewsii .In the oligotrophic lake P.pectinatus,P.illinoensi s,and the Characeae Chara rusbyana ,Ch.globularis and Nitella acuminata occur.The maximum depth of the macrophyte ’s presence can be used as an indicator of the trophic state,ranging from about 5 m in Mica to 35 m in Cuicocha.The bioindication value of the macrophyte species in these high Andean lakes is low,because few species occur and because some of them are not specific to environmental conditions.Rev.Biol.Trop.52(4:829-837.Epub 2005 Jun 24.

  19. Synthesis of lower treeline limber pine (Pinus flexilis) woodland knowledge, research needs, and management considerations

    Robert E. Means


    Lower treeline limber pine woodlands have received little attention in peer-reviewed literature and in management strategies. These ecologically distinct systems are thought to be seed repositories between discontinuous populations in the northern and central Rocky Mountains, serving as seed sources for bird dispersal between distinct mountain ranges. Their position on...

  20. Examining maternal effects and genetic differentiation in P. flexilis and P. aristata to improve success of conservation actions

    Erin M. Borgman


    As the climate changes and invasive species continue to spread, proactive management may be needed to conserve native plant populations. Selecting appropriate plant material for restoration or other actions that will sustain populations is an integral part of any such plan and must take into account genetic differentiation to limit maladaptation. Common garden studies...

  1. 78 FR 9876 - Endangered and Threatened Wildlife and Plants; Endangered Status and Designation of Critical...


    ... (Pinus flexilis); ponderosa pine (Pinus ponderosa); and aspen (Populus tremuloides); and (b) Has an... pine (Pinus flexilis); ponderosa pine (Pinus ponderosa); and aspen (Populus tremuloides); and (B) Has...

  2. Sugar composition of the pectic polysaccharides of charophytes, the closest algal relatives of land-plants: presence of 3-O-methyl-D-galactose residues.

    O'Rourke, Christina; Gregson, Timothy; Murray, Lorna; Sadler, Ian H; Fry, Stephen C


    During evolution, plants have acquired and/or lost diverse sugar residues as cell-wall constituents. Of particular interest are primordial cell-wall features that existed, and in some cases abruptly changed, during the momentous step whereby land-plants arose from charophytic algal ancestors. Polysaccharides were extracted from four charophyte orders [Chlorokybales (Chlorokybus atmophyticus), Klebsormidiales (Klebsormidium fluitans, K. subtile), Charales (Chara vulgaris, Nitella flexilis), Coleochaetales (Coleochaete scutata)] and an early-diverging land-plant (Anthoceros agrestis). 'Pectins' and 'hemicelluloses', operationally defined as extractable in oxalate (100 °C) and 6 m NaOH (37 °C), respectively, were acid- or Driselase-hydrolysed, and the monosaccharides analysed chromatographically. One unusual monosaccharide, 'U', was characterized by (1)H/(13)C-nuclear magnetic resonance spectroscopy and also enzymically. 'U' was identified as 3-O-methyl-D-galactose (3-MeGal). All pectins, except in Klebsormidium, contained acid- and Driselase-releasable galacturonate, suggesting homogalacturonan. All pectins, without exception, released rhamnose and galactose on acid hydrolysis; however, only in 'higher' charophytes (Charales, Coleochaetales) and Anthoceros were these sugars also efficiently released by Driselase, suggesting rhamnogalacturonan-I. Pectins of 'higher' charophytes, especially Chara, contained little arabinose, instead possessing 3-MeGal. Anthoceros hemicelluloses were rich in glucose, xylose, galactose and arabinose (suggesting xyloglucan and arabinoxylan), none of which was consistently present in charophyte hemicelluloses. Homogalacturonan is an ancient streptophyte feature, albeit secondarily lost in Klebsormidium. When conquering the land, the first embryophytes already possessed rhamnogalacturonan-I. In contrast, charophyte and land-plant hemicelluloses differ substantially, indicating major changes during terrestrialization. The presence of 3

  3. Aproximación a las comunidades de carófitos que existieron en la Albufera de Valencia a partir del estudio de las oósporas del sedimento

    Soulié-Märsche, Ingeborg


    Full Text Available Charophyte oospores and their features (size, shape, colour, outer wall ornamentation, etc. are able to persist in seed banks of aquatic ecosystems. Thus, these characteristics can be used for taxonomic species identification, thereby providing knowledge about the specific composition of the charophyte community in a habitat that currently lacks, or has greatly altered, submerged vegetation. Several years ago, l’Albufera de València lost the charophyte meadows that covered the lake bottom in the past, which had never been studied in detail. Several sediment cores were extracted from the lagoon at three sites and the oospores and gyrogonites were isolated and characterized. The oospore/gyrogonite densities in the sediment layers were estimated. Ten different taxa have been identified: six belonging to genus Chara [Ch. vulgaris, Ch. Hispida var. major, Ch. fragilis (Ch. globularis, Ch. Hispida var. baltica, Ch. aspera, Ch. tomentosa]; one Nitella species (N. hyalina, two Tolypella species (T. glomerata and T. hispanica and one Lamprothamnium species (L. papulosum. The latter, which indicates the period when water salinity was high in the lagoon, was found in the deepest sediment layers. An increase in the oospore abundance and diversity was observed in line with sediment depth. This indicates, on the one hand, that the lagoon went through different ecological stages (with important changes in salinity, mainly and, on the other hand, the eutrophication process that the lagoon has been undergoing for at least the last 45 years, has progressively affected the abundance and diversity of the charophyte community.

    Las oósporas de carófitos y sus características (tamaño, forma, color, ornamentación de la pared, etc. pueden persistir en los bancos de semillas del sedimento de ecosistemas acuáticos, y pueden ser utilizadas para identificar los diferentes táxones y obtener de este modo una

  4. A new species of Euonymus (Celastraceae) from Australia

    Hou, Ding


    Euonymus globularis, a new species from Queensland, is here described. It is the second species of Euonymus for Australia. It shows reticulate affinities with species belonging to different sections or series of this genus as well as with species of Brassiantha and Hedraianthera in the same family.

  5. The influence of hyperthermia and irradiation on some bioelectric parameters of the cells

    Solic, F.; Milotic, B.; Stipcic-Solic, N.


    The simultaneously influence of hyperthermia and low intensity gamma irradiation on the biopotential and the resistance of Nitella cells were investigated. The effect induced by irradiation and hyperthermia is manifested as membrane repolarization while hyperthermia alone induced depolarization. The resistance of cells is in positive correlation with membrane potential. (author)

  6. Experimental Analysis of Cell Function Using Cytoplasmic Streaming

    Janssens, Peter; Waldhuber, Megan


    This laboratory exercise investigates the phenomenon of cytoplasmic streaming in the fresh water alga "Nitella". Students use the fungal toxin cytochalasin D, an inhibitor of actin polymerization, to investigate the mechanism of streaming. Students use simple statistical methods to analyze their data. Typical student data are provided. (Contains 3…

  7. Limber pine health in the Canadian Rockies

    Cyndi M. Smith; David Langor; Colin Myrholm; Jim Weber; Cameron Gillies; Jon Stuart-Smith


    Limber pine (Pinus flexilis) reaches the northern limit of its range at about 52 degrees latitude in Alberta (AB) and 51 degrees latitude in British Columbia (BC). Most populations are found on the eastern slopes of the Rocky Mountains, with a few disjunct populations west of the Continental Divide in southeastern BC.

  8. Sugar pine seed harvest by Clark's nutcracker: Annual use of a transient resource in Crater Lake National Park, Oregon

    Taylor J. Turner; Diana F. Tomback; Bradley Van Anderson; Michael Murray


    Clark's nutcrackers (Nucifraga columbiana) are well known for using conifer seeds as their principal nutriment source. Seeds are primarily harvested from whitebark (Pinus albicaulis), piñon (P. edulis), limber (P. flexilis), southwestern white (P. strobiformis), Jeffrey (P. jeffreyi), and ponderosa (P. ponderosa) pine as well as Douglas-fir (Pseudotsuga menziesii...

  9. Native ectomycorrhizal fungi of limber and whitebark pine: Necessary for forest sustainability?

    Cathy L. Cripps; Robert K. Antibus


    Ectomycorrhizal fungi are an important component of northern coniferous forests, including those of Pinus flexilis (limber pine) and P. albicaulis (whitebark pine) which are being decimated by white pine blister rust and mountain pine beetles. Ectomycorrhizal fungi are known to promote seedling establishment, tree health, and may play a role in forest sustainability....

  10. Monitoring limber pine health in the Rocky Mountains and North Dakota

    Kelly Burns; Jim Blodgett; Marcus Jackson; Brian Howell; William Jacobi; Anna Schoettle; Anne Marie Casper; Jennifer Klutsch


    Limber pine (Pinus flexilis James) is an ecologically and culturally important, yet little studied, tree species within the Western United States. Its distribution extends from Alberta and southeastern British Colombia to New Mexico, Arizona, and southeastern California with isolated populations in North Dakota, South Dakota, Nebraska, eastern Oregon...

  11. Distribution and hosts of Stellicola (Copepoda, Cyclopoida) associated with Linckia (Asteroidea) in the Indo-West Pacific

    Humes, Arthur G.


    Five lichomolgid copepods belonging to the genus Stellicola are reported from three species of the sea star genus Linckia in the Moluccas: Stellicola flexilis n. sp. from Linckia guildingi. L. laevigata, and L. multiflora, S. caeruleus (Stebbing, 1900) from L. laevigata, L. guildingi, and L.

  12. Selection for resistance to white pine blister rust affects the abiotic stress tolerances of limber pine

    Patrick J. Vogan; Anna W. Schoettle


    Limber pine (Pinus flexilis) mortality is increasing across the West as a result of the combined stresses of white pine blister rust (Cronartium ribicola; WPBR), mountain pine beetle (Dendroctonus ponderosae), and dwarf mistletoe (Arceuthobium cyanocarpum) in a changing climate. With the continued spread of WPBR, extensive mortality will continue with strong selection...

  13. White pine blister rust resistance in limber pine: Evidence for a major gene

    A. W. Schoettle; R. A. Sniezko; A. Kegley; K. S. Burns


    Limber pine (Pinus flexilis) is being threatened by the lethal disease white pine blister rust caused by the non-native pathogen Cronartium ribicola. The types and frequencies of genetic resistance to the rust will likely determine the potential success of restoration or proactive measures. These first extensive inoculation trials using individual tree seed collections...

  14. Limber pine forests on the leading edge of white pine blister rust distribution in Northern Colorado

    Jennifer G. Klutsch; Betsy A. Goodrich; Anna W. Schoettle


    The combined threats of the current mountain pine beetle (Dendroctonus ponderosae, MPB) epidemic with the imminent invasion of white pine blister rust (caused by the non-native fungus Cronartium ribicola, WPBR) in limber pine (Pinus flexilis) forests in northern Colorado threatens the limber pine's regeneration cycle and ecosystem function. Over one million...

  15. Recruitment patterns and growth of high-elevation pines in response to climatic variability (1883–2013), in the western Great Basin, USA

    Constance I. Millar; Robert D. Westfall; Diane L. Delany; Alan L. Flint; Lorraine E. Flint


    Over the period 1883–2013, recruitment of subalpine limber pine (Pinus flexilis E. James) and Great Basin bristlecone pine (Pinus longaeva D.K. Bailey) above the upper tree line, below the lower tree line, and across middle-elevation forest borders occurred at localized sites across four mountain ranges in the western Great...

  16. Survey of nematodes associated with terrestrial slugs in Norway.

    Ross, J L; Ivanova, E S; Hatteland, B A; Brurberg, M B; Haukeland, S


    A survey of nematodes associated with terrestrial slugs was conducted for the first time in Norway. A total of 611 terrestrial slugs were collected from 32 sample sites. Slugs were identified by means of morphological examination, dissection of genitalia and molecular analysis using mitochondrial DNA. Twelve slug species were identified, representing four different slug families. Internal nematodes were identified by means of morphological analysis and the sequencing of the 18S rRNA gene. Of the sample sites studied, 62.5% were found to be positive for nematode parasites, with 18.7% of all slugs discovered being infected. Five nematode species were identified in this study: Alloionema appendiculatum, Agfa flexilis, Angiostoma limacis, Angiostoma sp. and Phasmarhabditis hermaphrodita. Of these species, only one nematode was previously undescribed (Angiostoma sp.). This is the first record of the presence of A. appendiculatum, A. flexilis and A. limacis in Norway.

  17. Environmental Assessment/Overseas Environmental Assessment for the F-35 Joint Strike Fighter Initial Operational Test and Evaluation


    shrub layer. White fir (Abies concolor) occurs at elevations above approximately 8,000 feet, with single leaf pinyon ( Pinus monophylla) and limber...pine ( Pinus flexilis). The South Range lies in the northeastern portion of the Mojave Desert. Creosote bush, white bursage, and saltbush...pools of water, of sufficient extent, to sustain populations during drought . Wildlife species associated with Mojave Desert habitats found in the

  18. Finding of No Significant Impact (FONSI): Environmental Assessment of the Farish Recreation Area Observatory and Cabin Construction


    Montane forest comprises approximately 34 percent of the study area. Montane forests within the study area are a mix of Ponderosa pine ( Pinus ...ponderosa), limber pine ( Pinus flexilis), lodgepole pine ( Pinus contorta), and Engelmann spruce (Picea engelmannii) in dry areas. Douglas-fir (Pseudotsuga... drought stress. El Paso County fire bans are enforced within Farish. The USAFA has instituted thinning operations to mitigate fire dangers (Strohm

  19. Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0)


    monophylla or P. edulis), junipers (Juniperus), cottonwoods (e.g., Populus fremontii), willows (Salix), or hardwoods (e.g., Quercus , Platanus...pine in association with incense cedar and California black oak ( Quercus kelloggii) on the western slopes and Jeffrey pine on the eastern slopes...corkbark fir (Abies lasiocarpa var. arizonica ), limber pine (Pinus flexilis), and bristlecone pine (P. aristata) (Bailey 1995). Black Hills (MLRA

  20. First report of the white pine blister rust pathogen, Cronartium ribicola, in Arizona

    M. L. Fairweather; Brian Geils


    White pine blister rust, caused by Cronartium ribicola J.C. Fisch., was found on southwestern white pine (Pinus flexilis James var. reflexa Engelm., synonym P. strobiformis Engelm.) near Hawley Lake, Arizona (Apache County, White Mountains, 34.024°N, 109.776°W, elevation 2,357 m) in April 2009. Although white pines in the Southwest (Arizona and New Mexico) have been...

  1. Molecular phylogenies support taxonomic revision of three species of Laurencia (Rhodomelaceae, Rhodophyta, with the description of a new genus

    Florence Rousseau


    Full Text Available The systematics of the Laurencia complex was investigated using a taxon-rich data set including the chloroplast ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL gene only and a character-rich data set combining mitochondrial cytochrome oxidase 1 (COI-5P, the rbcL marker, and the nuclear large subunit of the ribosomal operon (LSU. Bayesian and ML analyses of these data sets showed that three species hitherto placed in the genus Laurencia J.V.Lamour. were not closely related to Laurencia s. str. Laurencia caspica Zinova & Zaberzhinskaya was the sister group of the remaining Osmundea Stackh. species, L. crustiformans McDermid joined Palisada and L. flexilis Setch. consisted of an independent lineage. In light of these results a new genus, Ohelopapa F.Rousseau, Martin-Lescanne, Payri & L.Le Gall gen. nov., is proposed to accommodate L. flexilis. This new genus is morphologically characterized by four pericentral cells in each vegetative axial segment; however, it lacks ‘corps en cerise’ in cortical cells and secondary pit connections between cortical cells, which are characteristic of Laurencia. Three novel combinations are proposed to render the classification closer to a natural system: Ohelopapa flexilis (Setch. F.Rousseau, Martin-Lescanne, Payri & L.Le Gall comb. nov., Osmundea caspica (Zinova & Zaberzhinskaya Maggs & L.M.McIvor comb. nov. and Palisada crustiformans (McDermid A.R.Sherwood, A.Kurihara & K.W.Nam comb. nov.

  2. Evolution of green plants as deduced from 5S rRNA sequences.

    Hori, H; Lim, B L; Osawa, S


    We have constructed a phylogenic tree for green plants by comparing 5S rRNA sequences. The tree suggests that the emergence of most of the uni- and multicellular green algae such as Chlamydomonas, Spirogyra, Ulva, and Chlorella occurred in the early stage of green plant evolution. The branching point of Nitella is a little earlier than that of land plants and much later than that of the above green algae, supporting the view that Nitella-like green algae may be the direct precursor to land plants. The Bryophyta and the Pteridophyta separated from each other after emergence of the Spermatophyta. The result is consistent with the view that the Bryophyta evolved from ferns by degeneration. In the Pteridophyta, Psilotum (whisk fern) separated first, and a little later Lycopodium (club moss) separated from the ancestor common to Equisetum (horsetail) and Dryopteris (fern). This order is in accordance with the classical view. During the Spermatophyta evolution, the gymnosperms (Cycas, Ginkgo, and Metasequoia have been studied here) and the angiosperms (flowering plants) separated, and this was followed by the separation of Metasequoia and Cycas (cycad)/Ginkgo (maidenhair tree) on one branch and various flowering plants on the other.

  3. Leaf anatomy of the South African Danthonieae (Poaceae. XV. The genus Elytrophorus

    R. P. Ellis


    Full Text Available The leaf anatomy of  Elytrophorus globularis Hack, and  E. spicatus (Willd. A. Camus is described and illustrated from freshly fixed material from SWA/Namibia and Botswana. It is shown that these two species are anatomically indistinguishable. It is suggested that they are conspecific. and that  E. spicatus possibly represents juvenile plants with immature inflorescences. The anatomical evidence strongly refutes a chloridoid relationship for Elytrophorus but appears to support arundinoid affinities for the genus. Striking anatomical and ecological similarities exist between  Elytrophorus and  Sacciolepis huillensis (Rendle Stapf. No significant leaf anatomical differences separate  Elytrophorus from S.  huillensis and some of the other C3 panicoid taxa and. consequently,  Elytro­phorus may represent a link between the Arundinoideae and the Panicoideae.

  4. Geohydrology and limnology of Walden Pond, Concord, Massachusetts

    Colman, John A.; Friesz, Paul J.


    nitrogen inputs (858 kilograms per year) were dominated (30 percent) by plume water from the septic leach field and, possibly, by swimmers (34 percent). Phosphorus inputs (32 kilograms per year) were dominated by atmospheric dry deposition, background ground water, and estimated swimmer inputs. Swimmer inputs may represent more than 50 percent of the phosphorus load during the summer. The septic-system plume did not contribute phosphorus, but increased the nitrogen to phosphorus ratio for inputs from 41 to 59, on an atom-to-atom basis. The ratio of nitrogen to phosphorus in input loads and within the lake indicated algal growth would be strongly phosphorus limited. Nitrogen supply in excess of plant requirements may mitigate against nitrogen fixing organisms including undesirable blooms of cyanobacteria. Based on areal nutrient loading, Walden Pond is a mesotrophic lake. Hypolimnetic oxygen demand of Walden Pond has increased since a profile was measured in 1939. Currently (1999), the entire hypolimnion of Walden Pond becomes devoid of dissolved oxygen before fall turnover in late November; whereas historical data indicated dissolved oxygen likely remained in the hypolimnion during 1939. The complete depletion of dissolved oxygen likely causes release of phosphorus from the sediments. Walden Pond contains a large population of the deep-growing benthic macro alga Nitella, which has been hypothesized to promote water clarity in other clear-water lakes by sequestering nutrients and keeping large areas of the sediment surface oxygenated. Loss of Nitella populations in other lakes has correlated with a decline in water quality. Although the Nitella standing crop is large in Walden Pond, Nitella still appears to be controlled by nutrient availability. Decreasing phosphorus inputs to Walden Pond, by amounts under anthropogenic control would likely contribute to the stability of the Nitella population in the metalimnion, may reverse oxygen depletion in the hypolimnion, and decreas

  5. Kinetics of extracellular release of 14C-labelled organic carbon by submerged macrophytes

    Soendergaard, M.


    The release of extracellular organic carbon (EOC) by six submerged freswater macrophytes was measured in time course studies with a 14 C-technique. Incubation in light in an open water-flow system made it possible to assay the time courses of 14 C-fixation and the simultaneous release of labelled EOC. Heterotrophic utilization of the released products by epiphytic communities was measured. Two patterns of release kinetics were found: (1) Constant rates of release occurred during the incubations, (2) The rates still increased after 24 h of incubation. During the first hours of incubation the rates of release increased in all species. Elodea reached constant rates after 2-4 h and Littorella and Ceratophyllum demersum after about 20 h. In the experiments with C. submersum and Nitella the rates of release increased almost linearly during the entire incubation period. The kinetics of release were in agreement with the molecular weight distribution of the dissolved EOC measured with gel chromatography. Low molecular weight products ( 10000 Daltons) dominated the dissolved EOC released by C. submersum and Nitella. A large fraction (18-60%) of the total EOC could be recovered on filters with a pore size of 0.2 μm. This particulate fraction probably represents some abiotic removal. The quantities of relase were low in all species and did not exceed 0.9% of the photosynthetic carbon fixation. Heterotrophic uptake by the epiphytic communities was less than 10% of the EOC released. The results emphasize that the 14 C-labelling of extracellular products is a time dependent process. (author)

  6. Application of in-situ bioassays with macrophytes in aquatic mesocosm studies.

    Coors, Anja; Kuckelkorn, Jochen; Hammers-Wirtz, Monika; Strauss, Tido


    Aquatic mesocosm studies assess ecotoxicological effects of chemicals by using small artificial ponds as models of lentic ecosystems. In this study, methods of controlled insertion of macrophytes within an outdoor mesocosm study were explored. Although analytically confirmed concentrations of the model herbicide terbuthylazine were high enough to expect direct effects on phytoplankton, functional parameters and dominant taxa abundance indicated only minor and transient effects. In-situ assays with Lemna minor, Myriophyllum spicatum, Potamogeton lucens and Chara globularis revealed adverse effects at concentrations in accordance with literature data. Complex interactions such as nutrient limitation and competition were possible reasons for the observed growth promotion at the lower concentration of about 5 microg/l terbuthylazine. The approach of macrophyte in-situ bioassays within a mesocosm study proved to be applicable. Presumed advantages are simultaneous acquisition of toxicity data for several species of aquatic plants under more realistic conditions compared to laboratory tests and inclusion of macrophytes as important structural and functional components in mesocosms while limiting their domination of the model ecosystem.


    R. Bolpagni


    Full Text Available A detailed survey was performed to examine the floristic richness and the structural complexity, spatial patterns and conservation value of aquatic plant communities within the littorals of Lake Idro (northern Italy. During the summers of 2010-2011 we proceeded to characterize aquatic macrophyte meadows applying standardized procedures using transects (44 and plots (49 arrayed perpendicular to the shoreline and randomly positioned within the vegetated belt, respectively. Lake Idro is characterized by rather high floristic richness (20 macrophytes but low levels of vegetation structural complexity (8 vegetation units. Nevertheless, a clear zonation of the littoral vegetation was identified with two main macro-layers: a deeper layer (between 6-10 m of depth dominated by Chara globularis and an upper one (from 6 m of depth to water-air atmosphere mainly colonized by alien elodeids (mainly Elodea nuttallii and Lagarosiphon major. For the first time a complete floristic-vegetation analysis of the Lake Idro was presented. Our data confirm the poor ecological status of the basin, even though the lacustrine vegetation can be considered of conservation concern. Further investigations are needed to improve present evaluations, especially with respect to the impact of eutrophication on macrophytic communities.

  8. Effect of abalone farming on seawater movement and benthic foraminiferal assemblage of Zostera marina in the inner bay of Wando, South Korea.

    Lee, Yeon Gyu; Choi, Yang Ho; Jeong, Da Un; Lee, Jung Sick; Kim, Yong Wan; Park, Jung Jun; Choi, Jae Ung


    Tidal current survey as well as geochemical and benthic foraminiferal analyses of sediment cores were conducted in an abalone farm and a Zostera bed to understand the degree to which the abalone farm facilities installed along a channel in a shallow sea affect the benthic environment and ecology. In the abalone farm, Ammonia beccarii-Pseudoparrella naraensis-Elphidium somaense-Rosalina globularis-Trochammina hadai and P. naraensis-E. somaense-A. beccarii-T. hadai assemblages appeared owing to an increase in the total nitrogen content from the biodeposits. The Zostera bed consisted of A. beccarii-P. naraensis-Buccella frigida-T. hadai assemblage owing to the gradual expansion of a brackish shallow-water environment by the rapidly decreasing current speed, and it may have flourished. Moreover, the total sulfur, Zn, Cr, and Cu contents in the sediments decreased remarkably more than those of the pre-abalone farming did, caused by the vigorous activity of Zostera marina physiology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Leapfrogging of tree species provenances? Interaction of microclimate and genetics on upward shifts in tree species' range limits

    Reinhardt, K.; Castanha, C.; Germino, M. J.; Kueppers, L. M.


    The elevation limit of tree growth (alpine treeline) is considered to be constrained by environmental (i.e., thermal) and genetic (i.e., inability to adapt to climatic conditions) limitations to growth. Warming conditions due to climate change are predicted to cause upward shifts in the elevation of alpine treelines, through relief of cold-induced physiological limitations on seedling recruitment beyond current treeline boundaries. To determine how genetics and climate may interact to affect seedling establishment, we transplanted recently germinated seedlings from high- and low-elevation provenances (HI and LO, respectively) of Pinus flexilis in common gardens arrayed along an elevation and canopy gradient from subalpine forest into the alpine zone at Niwot Ridge, CO. We compared differences in microclimate and seedling ecophysiology among sites and between provenances. During the first summer of growth, frequently cloudy skies resulted in similar solar radiation incidence and air and soil temperatures among sites, despite nearly a 500 m-span in elevation across all sites. Preliminary findings suggest that survival of seedlings was similar between the lowest and highest elevations, with greater survival of LO (60%) compared to HI (40%) seedlings at each of these sites. Photosynthesis, carbon balance (photosynthesis/respiration), and conductance increased more than 2X with elevation for both provenances, and were 35-77% greater in LO seedlings compared to HI seedlings. There were no differences in dark-adapted chlorophyll fluorescence (Fv/Fm) among sites or between provenances. However, in a common-garden study at low elevation, we observed no differences in carbon or water relations between two naturally-germinated mitochondrial haplotypes of P. flexilis (of narrow and wide-ranging distributions). We did observe water-related thresholds on seedling carbon balance and survival that occurred when soil volumetric water content dropped below 10% and seedling water

  10. Commented list of rare and protected vascular plants of inland water bodies of Estonia

    Helle Mäemets


    Full Text Available This presented overview of rare and protected hydrophytes, emergent plants and hygrophytes of inland water bodies of Estonia includes 60 species. In the commented list are indicated their position in the state protection categories I–III (last version in 2014, and under the Red List of Estonia (last version in 2008; marked are Natura 2000 species of the European Union. Most typical habitats for these rare species are: I. soft-water oligotrophic and semidystrophic lakes; II. mesotrophic lakes with Najas (Caulinia flexilis and Potamogeton rutilus; III. alkaline fens and wet meadows; IV. brackish or freshwater coastal lagoons; V. undamaged river stretches; VI. open shallow littoral of the largest lakes of Peipsi (Pskovsko-Chudskoe and of Võrtsjärv. Main threats of these habitats are briefly concerned, as well as the problem of conservation value of hybrids, based on the example of Sparganium species.

  11. Predicting aquatic macrophyte occurrence in soft-water oligotrophic lakes (Pyrenees mountain range

    Cristina Pulido


    Full Text Available Distribution of aquatic macrophytes in lakes is related to geographical, morphological, catchment and water chemistry variables as well as human impacts, which modify the original environment. Here, we aim at building statistical models to establish the ecological niches of 11 aquatic macrophytes (10 different phanerogams and the genus Nitella from oligotrophic soft-water lakes and infer their ecological requirements and environmental constraints at the southernmost limit of their distribution. Macrophyte occurrence and environmental variables were obtained from 86 non-exploited oligotrophic soft-water lakes from the Pyrenees (Southern Europe; 42º50´N, 1º00´E; macrophytes inhabited 55 of these lakes. Optimum ranges and macrophyte occurrence were predicted in relation to 18 geographical, morphological, catchment and water chemistry variables using univariate and multivariate logistic models. Lakes at low altitude, in vegetated catchments and with low water concentration of NO3- and SO4-2, were the most suitable to host macrophytes. In general, individual species of aquatic macrophytes showed clear patterns of segregation along conductivity and pH gradients, although the specific combination of variables selected in the best models explaining their occurrence differed among species.  Based on the species response to pH and conductivity, we found Isoetes lacustris have its optimum in waters with low conductivity and pH (i.e. negative monotonic response. In contrast, Callitriche palustris, Ranunculus aquatilis, Subularia aquatica, Nitella spp., and Myriophyllum alterniflorum showed an optimum at intermediate values (i.e. unimodal response, whereas Potamogeton berchtoldii, Potamogeton alpinus, and Ranunculus trichophyllus as species had their optimum at relatively high water pH and conductivity (i.e. positive monotonic response. This pattern has been observed in other regions for the same species, although with different optima and tolerance

  12. Conifer seedling recruitment across a gradient from forest to alpine tundra: effects of species, provenance, and site

    Castanha, C.; Torn, M.S.; Germino, M.J.; Weibel, Bettina; Kueppers, L.M.


    Background: Seedling germination and survival is a critical control on forest ecosystem boundaries, such as at the alpine–treeline ecotone. In addition, while it is known that species respond individualistically to the same suite of environmental drivers, the potential additional effect of local adaptation on seedling success has not been evaluated. Aims: To determine whether local adaptation may influence the position and movement of forest ecosystem boundaries, we quantified conifer seedling recruitment in common gardens across a subalpine forest to alpine tundra gradient at Niwot Ridge, Colorado, USA. Methods: We studied Pinus flexilis and Picea engelmannii grown from seed collected locally at High (3400 m a.s.l.) and Low (3060 m a.s.l.) elevations. We monitored emergence and survival of seeds sown directly into plots and survival of seedlings germinated indoors and transplanted after snowmelt. Results: Emergence and survival through the first growing season was greater for P. flexilis than P. engelmannii and for Low compared with High provenances. Yet survival through the second growing season was similar for both species and provenances. Seedling emergence and survival tended to be greatest in the subalpine forest and lowest in the alpine tundra. Survival was greater for transplants than for field-germinated seedlings. Conclusions: These results suggest that survival through the first few weeks is critical to the establishment of natural germinants. In addition, even small distances between seed sources can have a significant effect on early demographic performance – a factor that has rarely been considered in previous studies of tree recruitment and species range shifts.

  13. Arthropod gut symbionts from the Balearic Islands: Majorca and Cabrera. Diversity and biogeography

    Guàrdia Valle, Laia


    Full Text Available This study includes a catalogue with all the current data concerning the presence of trichomycetes (sensu lato in Majorca and Cabrera, as well as information on the biology, ecology and biogeographic implications of the insularity for each taxon of these arthropod-gut symbionts. Of the 13 species here reported, 10 are new for the Balearic Islands, including 4 Mesomycetozoan, of which 3 Eccrinales (Astreptonema gammari, Eccrinidus flexilis, Parataeniella dilatata, 1 Amoebidiales (Paramoebidium curvum and 6 kixckellomycotina Harpellales (Genistellospora homothallica, Harpella melusinae, Smittium culisetae, S. simulii, Stachylina grandispora and St. nana; the additional 3 were previously reported elsewhere: Asellaria ligiae (Aslleariales, Legeriomyces rarus and Stipella vigilans (Harpellales, but are here included as indissoluble part of the present Balearic catalogue. All taxa are commented, illustrated and their biogeographic implications are discussed.

    El presente estudio incluye una recopilación de todos los datos concernientes al conocimiento de los tricomicetos (sensu lato en las islas Baleares de Mallorca y Cabrera, incluyendo un catálogo de especies y notas sobre la biología, ecología e implicaciones biogeográficas de su insularidad. De las 13 especies citadas, 10 son nuevas para las Baleares, incluyendo 4 Mesomycetozoos, de los cuales 3 Eccrinales (Astreptonema gammari, Eccrinidus flexilis, Parataeniella dilatata, 1 Amoebidiales (Paramoebidium curvum y 6 Harpellales (kixckellomycotina (Genistellospora homothallica, Harpella melusinae, Smittium culisetae, S. simulii, Stachylina grandispora y St. nana; aunque las 3 especies restantes: Asellaria ligiae (Aslleariales, Legeriomyces rarus y Stipella vigilans (Harpellales fueron citadas anteriormente, se incluyen aquí brevemente como parte del catálogo.

  14. Heavy metal and trace elements in riparian vegetation and macrophytes associated with lacustrine systems in Northern Patagonia Andean Range.

    Juárez, Andrea; Arribére, María A; Arcagni, Marina; Williams, Natalia; Rizzo, Andrea; Ribeiro Guevara, Sergio


    Vegetation associated with lacustrine systems in Northern Patagonia was studied for heavy metal and trace element contents, regarding their elemental contribution to these aquatic ecosystems. The research focused on native species and exotic vascular plant Salix spp. potential for absorbing heavy metals and trace elements. The native species studied were riparian Amomyrtus luma, Austrocedrus chilensis, Chusquea culeou, Desfontainia fulgens, Escallonia rubra, Gaultheria mucronata, Lomatia hirsuta, Luma apiculata, Maytenus boaria, Myrceugenia exsucca, Nothofagus antarctica, Nothofagus dombeyi, Schinus patagonicus, and Weinmannia trichosperma, and macrophytes Hydrocotyle chamaemorus, Isöetes chubutiana, Galium sp., Myriophyllum quitense, Nitella sp. (algae), Potamogeton linguatus, Ranunculus sp., and Schoenoplectus californicus. Fresh leaves were analyzed as well as leaves decomposing within the aquatic bodies, collected from lakes Futalaufquen and Rivadavia (Los Alerces National Park), and lakes Moreno and Nahuel Huapi (Nahuel Huapi National Park). The elements studied were heavy metals Ag, As, Cd, Hg, and U, major elements Ca, K, and Fe, and trace elements Ba, Br, Co, Cr, Cs, Hf, Na, Rb, Se, Sr, and Zn. Geochemical tracers La and Sm were also determined to evaluate contamination of the biological tissues by geological particulate (sediment, soil, dust) and to implement concentration corrections.

  15. Exchange of certain radionuclides between environment and freshwater algae

    Marchyulenene, E. D.P.


    Data on the dynamics and levels of accumulation of strontium, cesium, cerium and ruthenium radionuclides by Charophyta and Cladophora fresh-water algae are presented. An attempt has been made to investigate some processes that accompany the accumulation of radionuclides by plants. Under experimental conditions, the intensity and levels of radionuclide accumulation can be presented in the following order: 144 Ce> 106 Ru> 90 Sr> 137 Cs. The dynamics of radionuclide accumulation varied greatly with the radionuclide and the algae species studied. The 144 Ce accumulation coefficients (AC) in the course of experiment (from 3 hours to 16 days) increased 8-, 9-, 23.4-, 27-, 14.3- and 20.4-fold for Cladophora glomerata, Nitella syncarpa, Nitellopsis obtusa, Chara vulgaris, Ch. rudis, and Ch. aspera, respectively. In the case of 106 Ru, AC for C.glomerata, N. syncarapa, Ch. vulgaris and Ch. rudis increased 34-, 18-,24- and 23-fold, respectively. In all algae species studied the equilibrium of radionuclide accumulation was attained after 2-4 days of experiment. Levels of accumulated 90 Sr and 137 Cs in most species depended on the season while that of 144 Cs and 106 Ru remained constant throughout the vegetation period. The levels of radionuclide elimination, like the accumulation levels, are shown to depend on both isotopes and algae species

  16. The removal of uranium from mining waste water using algal/microbial biomass

    Kalin, Margarete; Wheeler, W.N.; Meinrath, G.


    We describe a three step process for the removal of uranium (U) from dilute waste waters. Step one involves the sequestration of U on, in, and around aquatic plants such as algae. Cell wall ligands efficiently remove U(VI) from waste water. Growing algae continuously renew the cellular surface area. Step 2 is the removal of U-algal particulates from the water column to the sediments. Step 3 involves reducing U(VI) to U(IV) and transforming the ions into stable precipitates in the sediments. The algal cells provide organic carbon and other nutrients to heterotrophic microbial consortia to maintain the low E H , within which the U is transformed. Among the microorganisms, algae are of predominant interest for the ecological engineer because of their ability to sequester U and because some algae can live under many extreme environments, often in abundance. Algae grow in a wide spectrum of water qualities, from alkaline environments (Chara, Nitella) to acidic mine drainage waste waters (Mougeotia, Ulothrix). If they could be induced to grow in waste waters, they would provide a simple, long-term means to remove U and other radionuclides from U mining effluents. This paper reviews the literature on algal and microbial adsorption, reduction, and transformation of U in waste streams, wetlands, lakes and oceans

  17. Algunos aspectos de la variabilidad de los oogonios en poblaciones actuales del género Chara (Charophyceae. Aplicación paleontológica

    Pedrola, J.


    Full Text Available A critical revision of some useful taxonomic criteria in paleontology of Charophytes is carried Out. The results are based in four modern populations ((Chara aculeolata, Chara aff.baltica, Chara delicatula and Chara globularis and they permit to make some serious objections to these critera. The results are related with three principal aspects: the meaning of the absolute magnitudes of me girogonite, the behaviour of his joint variation and the morphological variability during the calcification process. In general, and for each one of the four populations, an absence of influence of the position of the girogonite over their measurements is observed. This doesn't happens when the verticil is considered as source of variation. These biometrical differences which are equivalent to some of those that has been used to distinguish fossil species, are not due to a process of progressive or heteregenous calcification in the secuence of verticils of me plant. Several arguments against the indiscriminate use of cocients between absolute magnitudes (e.g. the polarity index as detectors of systematic interest are showed. In the same way, some remarks to the use of the morphology of the spiral calcificated cells, the prominence of the basal pore and some aspects of the apex shape, as taxonomic criteria are made. All this are variable within the same plant when there are differents in the calcification degree of the girogonites.

    Se hace una revisión crítica de-algunos criterios taxonómicos de uso habitual en paleontología de carofitas. Sus resultados, basados en cuatro poblaciones actuales (Chara aculeolata, Chara aff.baltica, Chara delicatula y Chara globularis, permiten hacer algunas serias objeciones a estos criterios. Dichos resultados se relacionan con tres aspectos principales: el significado de las magnitudes absolutas del girogonito, el comportamiento de su variación conjunta y la variabilidad

  18. Experimental evidence for enhanced top-down control of freshwater macrophytes with nutrient enrichment.

    Bakker, Elisabeth S; Nolet, Bart A


    The abundance of primary producers is controlled by bottom-up and top-down forces. Despite the fact that there is consensus that the abundance of freshwater macrophytes is strongly influenced by the availability of resources for plant growth, the importance of top-down control by vertebrate consumers is debated, because field studies yield contrasting results. We hypothesized that these bottom-up and top-down forces may interact, and that consumer impact on macrophyte abundance depends on the nutrient status of the water body. To test this hypothesis, experimental ponds with submerged vegetation containing a mixture of species were subjected to a fertilization treatment and we introduced consumers (mallard ducks, for 8 days) on half of the ponds in a full factorial design. Over the whole 66-day experiment fertilized ponds became dominated by Elodea nuttallii and ponds without extra nutrients by Chara globularis. Nutrient addition significantly increased plant N and P concentrations. There was a strong interactive effect of duck presence and pond nutrient status: macrophyte biomass was reduced (by 50%) after the presence of the ducks on fertilized ponds, but not in the unfertilized ponds. We conclude that nutrient availability interacts with top-down control of submerged vegetation. This may be explained by higher plant palatability at higher nutrient levels, either by a higher plant nutrient concentration or by a shift towards dominance of more palatable plant species, resulting in higher consumer pressure. Including nutrient availability may offer a framework to explain part of the contrasting field observations of consumer control of macrophyte abundance.

  19. Selandian-Thanetian larger foraminifera from the lower Jafnayn Formation in the Sayq area (eastern Oman Mountains)

    Serra-Kiel, J.; Vicedo, V.; Razin, P.; Grelaud, C.


    The larger foraminifera of the lower part of the Jafnayn Formation outcropping in the Wadi Sayq, in the Paleocene series of the eastern Oman Mountains, have been studied and described in detail. The analysis have allowed us to develop a detailed systematic description of each taxa, constraining their biostratigraphic distribution and defining the associated foraminifera assemblages. The taxonomic study has permitted us to identify each morphotype precisely and describe three new taxa, namely, Ercumentina sayqensis n. gen. n. sp. Lacazinella rogeri n. sp. and Globoreticulinidae new family. The first assemblage is characterized by the presence of Coskinon sp., Dictyoconus cf. turriculus Hottinger and Drobne, Anatoliella ozalpiensis Sirel, Ercumentina sayqensis n. gen. n. sp. SerraKiel and Vicedo, Lacazinella rogeri n. sp. Serra-Kiel and Vicedo, Mandanella cf. flabelliformis Rahaghi, Azzarolina daviesi (Henson), Lockhartia retiata Sander, Dictyokathina simplex Smout and Miscellanites globularis (Rahaghi). The second assemblage is constituted by the forms Pseudofallotella persica (Hottinger and Drobne), Dictyoconus cf. turriculus Hottinger and Drobne, Lacazinella rogeri n. sp. Serra-Kiel and Vicedo, Azzarolina daviesi (Henson), Keramosphera? cf. iranica Rahaghi, Lockhartia haimei (Davies), Lockhartia retiata Sander, Sakesaria trichilata Sander, Kathina delseota Smout, Elazigina harabekayisensis Sirel, Daviesina khatiyahi Smout, and Miscellanea juliettae Leppig. The first assemblage can be considered to belong to the Shallow Bentic Zone SBZ2 (early Selandian age), and the second assemblage to the SBZ3 (late Selandian-early Thanetian age).This paper shows, for the first time in the Middle East area, a correlation between the Selandian larger foraminifera and planktonic foraminifera biozones. (Author)

  20. Selandian-Thanetian larger foraminifera from the lower Jafnayn Formation in the Sayq area (eastern Oman Mountains)

    Serra-Kiel, J.; Vicedo, V.; Razin, P.; Grelaud, C.


    The larger foraminifera of the lower part of the Jafnayn Formation outcropping in the Wadi Sayq, in the Paleocene series of the eastern Oman Mountains, have been studied and described in detail. The analysis have allowed us to develop a detailed systematic description of each taxa, constraining their biostratigraphic distribution and defining the associated foraminifera assemblages. The taxonomic study has permitted us to identify each morphotype precisely and describe three new taxa, namely, Ercumentina sayqensis n. gen. n. sp. Lacazinella rogeri n. sp. and Globoreticulinidae new family. The first assemblage is characterized by the presence of Coskinon sp., Dictyoconus cf. turriculus Hottinger and Drobne, Anatoliella ozalpiensis Sirel, Ercumentina sayqensis n. gen. n. sp. SerraKiel and Vicedo, Lacazinella rogeri n. sp. Serra-Kiel and Vicedo, Mandanella cf. flabelliformis Rahaghi, Azzarolina daviesi (Henson), Lockhartia retiata Sander, Dictyokathina simplex Smout and Miscellanites globularis (Rahaghi). The second assemblage is constituted by the forms Pseudofallotella persica (Hottinger and Drobne), Dictyoconus cf. turriculus Hottinger and Drobne, Lacazinella rogeri n. sp. Serra-Kiel and Vicedo, Azzarolina daviesi (Henson), Keramosphera? cf. iranica Rahaghi, Lockhartia haimei (Davies), Lockhartia retiata Sander, Sakesaria trichilata Sander, Kathina delseota Smout, Elazigina harabekayisensis Sirel, Daviesina khatiyahi Smout, and Miscellanea juliettae Leppig. The first assemblage can be considered to belong to the Shallow Bentic Zone SBZ2 (early Selandian age), and the second assemblage to the SBZ3 (late Selandian-early Thanetian age).This paper shows, for the first time in the Middle East area, a correlation between the Selandian larger foraminifera and planktonic foraminifera biozones. (Author)

  1. Phylogeny of Celastraceae tribe Euonymeae inferred from morphological characters and nuclear and plastid genes.

    Simmons, Mark P; McKenna, Miles J; Bacon, Christine D; Yakobson, Kendra; Cappa, Jennifer J; Archer, Robert H; Ford, Andrew J


    The phylogeny of Celastraceae tribe Euonymeae (≈ 230 species in eight genera in both the Old and New Worlds) was inferred using morphological characters together with plastid (matK, trnL-F) and nuclear (ITS and 26S rDNA) genes. Tribe Euonymeae has been defined as those genera of Celastraceae with generally opposite leaves, isomerous carpels, loculicidally dehiscent capsules, and arillate seeds (except Microtropis). Euonymus is the most diverse (129 species) and widely cultivated genus in the tribe. We infer that tribe Euonymeae consists of at least six separate lineages within Celastraceae and that a revised natural classification of the family is needed. Microtropis and Quetzalia are inferred to be distinct sister groups that together are sister to Zinowiewia. The endangered Monimopetalum chinense is an isolated and early derived lineage of Celastraceae that represents an important component of phylogenetic diversity within the family. Hedraianthera is sister to Brassiantha, and we describe a second species (Brassiantha hedraiantheroides A.J. Ford) that represents the first reported occurrence of this genus in Australia. Euonymus globularis, from eastern Australia, is sister to Menepetalum, which is endemic to New Caledonia, and we erect a new genus (Dinghoua R.H. Archer) for it. The Madagascan species of Euonymus are sister to Pleurostylia and recognized as a distinct genus (Astrocassine ined.). Glyptopetalum, Torralbasia, and Xylonymus are all closely related to Euonymus sensu stricto and are questionably distinct from it. Current intrageneric classifications of Euonymus are not completely natural and require revision. Copyright © 2011 Elsevier Inc. All rights reserved.

  2. Selective Herbivory by an Invasive Cyprinid, the Rudd Scardinius erythrophthalmus

    Kapuscinski, Kevin L [SUNY-ESF, SUNY College of Environmental Science and Forestry; John, Farrell M [SUNY-ESF, SUNY College of Environmental Science and Forestry; Stehman, Stephen V [SUNY-ESF, SUNY College of Environmental Science and Forestry; Boyer, Gregory L [SUNY-ESF, SUNY College of Environmental Science and Forestry; Fernando, Danilo D [SUNY-ESF, SUNY College of Environmental Science and Forestry; Teece, Mark A [SUNY-ESF, SUNY College of Environmental Science and Forestry; Tschaplinski, Timothy J [ORNL


    1. Herbivory by non-native animals is a problem of growing concern globally, especially for ecosystems where significant native herbivores did not previously exist or have been replaced by non-natives. The rudd (Scardinius erythrophthalmus) is an omnivorous cyprinid that has a nearly global longitudinal distribution due to human translocations, yet it is unknown whether the rudd feeds selectively among aquatic macrophyte species common to North American waters. 2. We tested a null hypothesis of non-selective feeding by rudds using five species of aquatic macrophytes: Ceratophyllum demersum, Elodea canadensis, Najas flexilis, Stuckenia pectinata, and Vallisneria americana. Four rudds were placed in 15 different 890-L tanks and presented with known quantities of each macrophyte species (each tank serving as a block in a randomized complete block design). Each macrophyte bundle was weighed on six dates during a 13 d experiment. Differences in mean percent weight remaining among macrophyte species were tested using repeated measures analysis of variance. We also quantified differences among chemical attributes of the five macrophyte species and qualitatively determined if selective feeding by rudds was related to dry matter content (DMC), percent C by dry weight (%C), percent N by dry weight (%N), and the concentrations of total soluble proteins, two organic acids (aconitic and oxalic acid), total soluble phenolic compounds (<1,000 Da), nine soluble phenolic metabolites, and total phenolic compounds. 3. Selective feeding by rudds was evident, with the order of macrophyte removal (from highest to lowest) being: N. flexilis > E. canadensis > S. pectinata > V. americana > C. demersum. Selection was positively related to %C and atomic C:N, but not DMC, %N, or concentration of total soluble proteins, contrary to the expectation that rudds would select the most nutritious plants available. The concentration of aconitic acid was greatest in N. flexilis, a preferred macrophyte

  3. Growth strategies and threshold responses to water deficit modulate effects of warming on tree seedlings from forest to alpine

    Lazarus, Brynne E.; Castanha, Cristina; Germino, Matthew; Kueppers, Lara M.; Moyes, Andrew B.


    1.Predictions of upslope range shifts for tree species with warming are based on assumptions of moisture stress at lower elevation limits and low temperature stress at high elevation limits. However, recent studies have shown that warming can reduce tree seedling establishment across the entire gradient from subalpine forest to alpine via moisture limitation. Warming effects also vary with species, potentially resulting in community shifts in high elevation forests. 2.We examined the growth and physiology underlying effects of warming on seedling demographic patterns. We evaluated dry mass (DM), root length, allocation above- and belowground, and relative growth rate (RGR) of whole seedlings, and their ability to avoid or endure water stress via water-use efficiency and resisting turgor loss, for Pinus flexilis, Picea engelmannii and Pinus contorta seeded below, at, and above treeline in experimentally warmed, watered, and control plots in the Rocky Mountains, USA. We expected that growth and allocation responses to warming would relate to moisture status and that variation in drought tolerance traits would explain species differences in survival rates. 3.Across treatments and elevations, seedlings of all species had weak turgor-loss resistance, and growth was marginal with negative RGR in the first growth phase (-0.01 to -0.04 g/g/d). Growth was correlated with soil moisture, particularly in the relatively small-seeded P. contorta and P. engelmannii. P. flexilis, known to have the highest survivorship, attained the greatest DM and longest root but was also the slowest growing and most water-use-efficient. This was likely due to its greater reliance on seed reserves. Seedlings developed 15% less total DM, 25% less root DM, and 11% shorter roots in heated compared to unheated plots. Higher temperatures slightly increased DM, root length and RGR where soils were wettest, but more strongly decreased these variables under drier conditions. 4.Synthesis: The surprising

  4. Comparative Transcriptomics Among Four White Pine Species

    Ethan A. G. Baker


    Full Text Available Conifers are the dominant plant species throughout the high latitude boreal forests as well as some lower latitude temperate forests of North America, Europe, and Asia. As such, they play an integral economic and ecological role across much of the world. This study focused on the characterization of needle transcriptomes from four ecologically important and understudied North American white pines within the Pinus subgenus Strobus. The populations of many Strobus species are challenged by native and introduced pathogens, native insects, and abiotic factors. RNA from the needles of western white pine (Pinus monticola, limber pine (Pinus flexilis, whitebark pine (Pinus albicaulis, and sugar pine (Pinus lambertiana was sampled, Illumina short read sequenced, and de novo assembled. The assembled transcripts and their subsequent structural and functional annotations were processed through custom pipelines to contend with the challenges of non-model organism transcriptome validation. Orthologous gene family analysis of over 58,000 translated transcripts, implemented through Tribe-MCL, estimated the shared and unique gene space among the four species. This revealed 2025 conserved gene families, of which 408 were aligned to estimate levels of divergence and reveal patterns of selection. Specific candidate genes previously associated with drought tolerance and white pine blister rust resistance in conifers were investigated.

  5. Moisture rivals temperature in limiting photosynthesis by trees establishing beyond their cold-edge range limit under ambient and warmed conditions.

    Moyes, Andrew B; Germino, Matthew J; Kueppers, Lara M


    Climate change is altering plant species distributions globally, and warming is expected to promote uphill shifts in mountain trees. However, at many cold-edge range limits, such as alpine treelines in the western United States, tree establishment may be colimited by low temperature and low moisture, making recruitment patterns with warming difficult to predict. We measured response functions linking carbon (C) assimilation and temperature- and moisture-related microclimatic factors for limber pine (Pinus flexilis) seedlings growing in a heating × watering experiment within and above the alpine treeline. We then extrapolated these response functions using observed microclimate conditions to estimate the net effects of warming and associated soil drying on C assimilation across an entire growing season. Moisture and temperature limitations were each estimated to reduce potential growing season C gain from a theoretical upper limit by 15-30% (c. 50% combined). Warming above current treeline conditions provided relatively little benefit to modeled net assimilation, whereas assimilation was sensitive to either wetter or drier conditions. Summer precipitation may be at least as important as temperature in constraining C gain by establishing subalpine trees at and above current alpine treelines as seasonally dry subalpine and alpine ecosystems continue to warm. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  6. Tree-ring-based reconstruction of precipitation in the Bighorn Basin, Wyoming, since 1260 A.D

    Gray, S.T.; Fastie, C.L.; Jackson, S.T.; Betancourt, J.L.


    Cores and cross sections from 79 Douglas fir (Pseudotsuga menziesii) and limber pine (Pinus flexilis) trees at four sites in the Bighorn Basin of north-central Wyoming and south-central Montana were used to develop a proxy for annual (June-June) precipitation spanning 1260-1998 A.D. The reconstruction exhibits considerable nonstationarity, and the instrumental era (post-1900) in particular fails to capture the full range of precipitation variability experienced in the past ???750 years. Both single-year and decadal-scale dry events were more severe before 1900. Dry spells in the late thirteenth and sixteenth centuries surpass both magnitude and duration of any droughts in the Bighorn Basin after 1900. Precipitation variability appears to shift to a higher-frequency mode after 1750, with 15-20-yr droughts becoming rare. Comparisons between instrumental and reconstructed values of precipitation and indices of Pacific basin variability reveal that precipitation in the Bighorn Basin generally responds to Pacific forcing in a manner similar to that of the southwestern United States (drier during La Nin??a events), but high country precipitation in areas surrounding the basin displays the opposite response (drier during El Nin??o events). ?? 2004 American Meteorological Society.

  7. Instrumenting the Conifers: A Look at Daily Tree Growth and Locally Observed Environmental Conditions Across Four Mountain Sites in the Central Great Basin, USA

    Strachan, S.; Biondi, F.; Johnson, B. G.


    Tree growth is often used as a proxy for past environmental conditions or as an indicator of developing trends. Reconstructions of drought, precipitation, temperature, and other phenomena derived from tree-growth indices abound in scientific literature aimed at informing policy makers. Observations of tree recruitment or death in treeline populations are frequently tied to climatic fluctuation in cause-effect hypotheses. Very often these hypotheses are based on statistical relationships between annual-to-seasonal tree growth measurements and some environmental parameter measured or modeled off-site. Observation of daily tree growth in conjunction with in-situ environmental measurements at similar timescales takes us one step closer to quantifying the uncertainty in reconstruction or predictive studies. In four separate sites in two different mountain ranges in the central Great Basin, co-located observations of conifer growth activity and local atmospheric and soils conditions have been initiated. Species include Pinus longaeva (Great Basin bristlecone pine), Pinus flexilis (limber pine), Picea engelmannii (Engelmann spruce), Pinus monophylla (singleleaf pinyon pine), Pinus ponderosa (ponderosa pine), Abies concolor (white fir), and Pseudotsuga menziesii (Douglas-fir). Measurements of sub-hourly tree radial length change and sap flow activity are compared with a suite of in-situ observations including air temperature, precipitation, photosynthetically-active radiation (PAR), relative humidity, soil temperature, and soil moisture/water content. Subalpine study site located at 3360 m elevation in the Snake Range, Nevada

  8. Lab and Field Warming Similarly Advance Germination Date and Limit Germination Rate for High and Low Elevation Provenances of Two Widespread Subalpine Conifers

    Lara M. Kueppers


    Full Text Available Accurately predicting upslope shifts in subalpine tree ranges with warming requires understanding how future forest populations will be affected by climate change, as these are the seed sources for new tree line and alpine populations. Early life history stages are particularly sensitive to climate and are also influenced by genetic variation among populations. We tested the climate sensitivity of germination and initial development for two widely distributed subalpine conifers, using controlled-environment growth chambers with one temperature regime from subalpine forest in the Colorado Rocky Mountains and one 5 °C warmer, and two soil moisture levels. We tracked germination rate and timing, rate of seedling development, and seedling morphology for two seed provenances separated by ~300 m elevation. Warming advanced germination timing and initial seedling development by a total of ~2 weeks, advances comparable to mean differences between provenances. Advances were similar for both provenances and species; however, warming reduced the overall germination rate, as did low soil moisture, only for Picea engelmannii. A three-year field warming and watering experiment planted with the same species and provenances yielded responses qualitatively consistent with the lab trials. Together these experiments indicate that in a warmer, drier climate, P. engelmannii germination, and thus regeneration, could decline, which could lead to declining subalpine forest populations, while Pinus flexilis forest populations could remain robust as a seed source for upslope range shifts.

  9. Seaweed tablet: a natural source of iodine

    Briones, Annabelle V.; Ambal, Wilhelmina O.; Monroyo, Evangelina C.; Bonifacio, Teresita S.; Sison, Fe M.


    Species of seaweeds namely: Halymenia durvillaei, Laurencia flexilis and Sargassum gigantifolium were processed into dried form and formulated as tablet. Prior to tablet formulation, the seaweeds were assayed for iodine and trace elements. The seaweeds that exhibited significance values of iodine and trace elements were further analyzed for the presence of heavy metals followed by acute oral toxicity test (LD 50 ). Among the seaweeds evaluated, H. durvilaei was found to contain high level of iodine (0.255% w/w) and magnesium (1.65% w/w) with sufficient amount of zinc (25.69 ppm) and phosporous (11.68 ppm). Analysis of heavy metals showed minute amount of mercury (0.0055 ppm), cadmium (0.67 ppm) and lead (1.80 ppm). The median lethal dose (LD 50 ) of H. durvillaei administered orally in Swiss male mice is 119.1489 ± 4.9873 g/kg. Tablet formulation was based on the U.S. recommended daily allowance of 0.15 mg. of iodine per adult and children. The final product was comparable to imported Kelp pills (available in the local market) in terms of physical properties and iodine content. (Author)

  10. Functional diversity of macrophyte communities within and between Pyrenean lakes



    Full Text Available Submersed vegetation is a common feature in about 70% Pyrenean high mountain (>1500 m a.s.l. lakes. Isoetids and soft-water elodeids are common elements of this underwater flora and can form distinct vegetation units (i.e. patches of vegetation dominated by different species within complex mosaics of vegetation in shallow waters (<7 m. Since isoetids exert a strong influence on sediment biogeochemistry due to high radial oxygen loss, we examined the small scale characteristics of the lake environment (water and sediment associated to vegetation patches in order to ascertain potential functional differences among them. To do so, we characterised the species composition and biomass of the main vegetation units from 11 lakes, defined plant communities based on biomass data, and then related each community with sediment properties (redox and dissolved nutrient concentration in the pore water and water nutrient concentration within plant canopy. We also characterised lake water and sediment in areas without vegetation as a reference. A total of twenty-one vegetation units were identified, ranging from one to five per lake. A cluster analysis on biomass species composition suggested seven different macrophyte communities that were named after the most dominant species: Nitella sp., Potamogeton praelongus, Myriophyllum alterniflorum, Sparganium angustifolium, Isoetes echinospora, Isoetes lacustris and Carex rostrata. Coupling between macrophyte communities and their immediate environment (overlying water and sediment was manifested mainly as variation in sediment redox conditions and the dominant form of inorganic nitrogen in pore-water. These effects depended on the specific composition of the community, and on the allocation between above- and belowground biomass, and could be predicted with a model relating the average and standard deviation of sediment redox potential from 0 down to -20 cm, across macrophyte communities. Differences in pore

  11. Carbon stable isotope composition of charophyte organic matter in a small and shallow Spanish water body as a baseline for future trophic studies

    María Antonia Rodrigo


    Full Text Available Quantitative descriptions of foodweb structure based on isotope niche space require knowledge of producers’ isotopic signatures. In freshwater ecosystems charophytes are one of the main components of submerged vegetation and the feeding base for many herbivorous consumers, but knowledge about their organic carbon isotopic signatures is sparse. In this study, the δ13C organic values (and organic %C and %N of the four species of submerged macrophytes (three charophytes - Chara hispida, Nitella hyalina and Tolypella glomerata - and one angiosperm, Myriophyllum spicatum growing in a newly created shallow pond were measured monthly over a period of one year, to discern if i all charophyte species susceptible to being food for consumers and growing in the same waterbody have the same C isotopic composition; ii the δ13C values of a charophyte species change on a seasonal and spatial scale; iii the different parts (apical nodes, internodes, rhizoids, reproductive organs, oospores of a charophyte species have the same isotopic composition. The δ13C, %C and %N values of organic matter in the sediments where the plants were rooted were also measured as well as several limnological variables. The δ13C values for the angiosperm (-13.7±0.7‰ indicated 13C-enrichment, whereas the N. hyalina δ13C values were the most negative (-22.4±0.7‰. The mean δ13C value for C. hispida was -19.0±1.0‰ and -20.7±0.8‰ for T. glomerata. C. hispida δ13C values had a significant seasonal variation with 13C-poor values in the cold season, and slight spatial differences. Statistically significant differences were found between charophyte rhizoids (13C-enriched and the other parts of the thalli. The δ13C values in the sediments varied throughout time (-13‰ to -26‰. The C content was lower in the charophytes than in the angiosperm and there were no large differences among the charophytes. Charophyte fructifications were enriched in organic C compared to the

  12. Allelopathic effects of microcystin-LR on the germination, growth and metabolism of five charophyte species and a submerged angiosperm.

    Rojo, Carmen; Segura, Matilde; Cortés, Francisco; Rodrigo, María A


    Microcystins (MCs) are produced by cyanobacteria in aquatic environments and adversely affect macrophytes at very high concentrations. However, the effects of MC on macrophytes at concentrations of environmental relevance are largely unknown. The main objective of this study was to analyze the allelopathic effects of MC-LR at natural concentrations (1, 8 and 16 μg MC-LR/L) on five charophyte species (Chara aspera, C. baltica, C. hispida, C. vulgaris and Nitella hyalina) and the angiosperm Myriophyllum spicatum. Macrophyte specimens were obtained from a restored area located in Albufera de València Natural Park, a protected coastal Mediterranean wetland. Two different experiments were conducted involving (i) the addition of MC-LR to natural sediment to evaluate its effects on seed germination and (ii) the addition of MC-LR to water cultures of macrophytes to evaluate its effects on growth and metabolic functions. In water, the MC-LR concentration decreased by 84% in two weeks; the loss was not significant in sediment. The first seedlings (all C. hispida) emerged from the wetland sediment following a delay of a few days in the presence of MC-LR. The germination rates in 8 and 16 μg MC-LR/L treatments were 44% and 11% of that occurring in the absence of MC, but these differences disappeared over time. The final density was 6-7 germlings/dm(3). Final germling length was unaffected by MC-LR. Rotifers (Lecane spp.) emerging from the natural sediment during the experiment were favored by MC-LR; the opposite pattern was observed in the cladoceran Daphnia magna. The growth rates of C. vulgaris, C. baltica and N. hyalina were unaffected by MC exposure, whereas those of C. hispida and C. aspera were reduced in the MC treatments relative to the control treatment. The concentration of chlorophyll-a and the in vivo net photosynthetic rate were lower in the presence of MC-LR, even at the lowest concentration, for all of the characeans tested. M. spicatum was sensitive to the

  13. Precipitation Reconstructions and Periods of Drought in the Upper Green River Basin, Wyoming, USA

    Follum, M.; Barnett, A.; Bellamy, J.; Gray, S.; Tootle, G.


    Due to recent drought and stress on water supplies in the Colorado River Compact States, more emphasis has been placed on the study of water resources in the Upper Green River Basin (UGRB) of Wyoming, Utah, and Colorado. The research described here focuses on the creation of long-duration precipitation records for the UGRB using tree-ring chronologies. When combined with existing proxy streamflow reconstructions and drought frequency analysis, these records offer a detailed look at hydrologic variability in the UGRB. Approximately thirty-three existing tree ring chronologies were analyzed for the UGRB area. Several new tree ring chronologies were also developed to enhance the accuracy and the geographical diversity of the resulting tree-ring reconstructions. In total, three new Douglas-fir (Pseudotsuga menziesii) and four new limber pine (Pinus flexilis) sites were added to the available tree-ring chronologies in this area. Tree-ring based reconstructions of annual (previous July through current June) precipitation were then created for each of the seventeen sub-watersheds in the UGRB. Reconstructed precipitation records extend back to at least 1654 AD, with reconstructions for some sub-basins beginning pre-1500. Variance explained (i.e. adjusted R2) ranged from 0.41 to 0.74, and the reconstructions performed well in a variety of verification tests. Additional analyses focused on stochastic estimation of drought frequency and return period, and detailed comparisons between reconstructed records and instrumental observations. Overall, this work points to the prevalence of severe, widespread drought in the UGRB. These analyses also highlight the relative wetness and lack of sustained dry periods during the instrumental period (1895-Present). Such long- term assessments are, in turn, vital tools as the Compact States contemplate the "Law of the River" in the face of climate change and ever-growing water demands.

  14. Low offspring survival in mountain pine beetle infesting the resistant Great Basin bristlecone pine supports the preference-performance hypothesis.

    Erika L Eidson

    Full Text Available The preference-performance hypothesis states that ovipositing phytophagous insects will select host plants that are well-suited for their offspring and avoid host plants that do not support offspring performance (survival, development and fitness. The mountain pine beetle (Dendroctonus ponderosae, a native insect herbivore in western North America, can successfully attack and reproduce in most species of Pinus throughout its native range. However, mountain pine beetles avoid attacking Great Basin bristlecone pine (Pinus longaeva, despite recent climate-driven increases in mountain pine beetle populations at the high elevations where Great Basin bristlecone pine grows. Low preference for a potential host plant species may not persist if the plant supports favorable insect offspring performance, and Great Basin bristlecone pine suitability for mountain pine beetle offspring performance is unclear. We infested cut bolts of Great Basin bristlecone pine and two susceptible host tree species, limber (P. flexilis and lodgepole (P. contorta pines with adult mountain pine beetles and compared offspring performance. To investigate the potential for variation in offspring performance among mountain pine beetles from different areas, we tested beetles from geographically-separated populations within and outside the current range of Great Basin bristlecone pine. Although mountain pine beetles constructed galleries and laid viable eggs in all three tree species, extremely few offspring emerged from Great Basin bristlecone pine, regardless of the beetle population. Our observed low offspring performance in Great Basin bristlecone pine corresponds with previously documented low mountain pine beetle attack preference. A low preference-low performance relationship suggests that Great Basin bristlecone pine resistance to mountain pine beetle is likely to be retained through climate-driven high-elevation mountain pine beetle outbreaks.

  15. Forecasting distributional responses of limber pine to climate change at management-relevant scales in Rocky Mountain National Park.

    William B Monahan

    Full Text Available Resource managers at parks and other protected areas are increasingly expected to factor climate change explicitly into their decision making frameworks. However, most protected areas are small relative to the geographic ranges of species being managed, so forecasts need to consider local adaptation and community dynamics that are correlated with climate and affect distributions inside protected area boundaries. Additionally, niche theory suggests that species' physiological capacities to respond to climate change may be underestimated when forecasts fail to consider the full breadth of climates occupied by the species rangewide. Here, using correlative species distribution models that contrast estimates of climatic sensitivity inferred from the two spatial extents, we quantify the response of limber pine (Pinus flexilis to climate change in Rocky Mountain National Park (Colorado, USA. Models are trained locally within the park where limber pine is the community dominant tree species, a distinct structural-compositional vegetation class of interest to managers, and also rangewide, as suggested by niche theory. Model forecasts through 2100 under two representative concentration pathways (RCP 4.5 and 8.5 W/m(2 show that the distribution of limber pine in the park is expected to move upslope in elevation, but changes in total and core patch area remain highly uncertain. Most of this uncertainty is biological, as magnitudes of projected change are considerably more variable between the two spatial extents used in model training than they are between RCPs, and novel future climates only affect local model predictions associated with RCP 8.5 after 2091. Combined, these results illustrate the importance of accounting for unknowns in species' climatic sensitivities when forecasting distributional scenarios that are used to inform management decisions. We discuss how our results for limber pine may be interpreted in the context of climate change

  16. Observing Semi-Arid Ecoclimates across Mountain Gradients in the Great Basin, USA

    Strachan, Scotty

    Observation of climate and ecohydrological variables in mountain systems is a necessary (if challenging) endeavor for modern society. Water resources are often intimately tied to mountains, and high elevation environments are frequently home to unique landscapes and biota with limited geographical distributions. This is especially true in the temperate and semi-arid mountains of the western United States, and specifically the Great Basin. Stark contrasts in annual water balance and ecological populations are visible across steep elevational gradients in the region; and yet the bulk of our historical knowledge of climate and related processes comes from lowland observations. Interpolative models that strive to estimate conditions in mountains using existing datasets are often found to be inaccurate, making future projections of mountain climate and ecosystem response suspect. This study details the results of high-resolution topographically-diverse ecohydrological monitoring, and describes the character and seasonality of basic climatic variables such as temperature and precipitation as well as their impact on soil moisture and vegetation during the 2012-2015 drought sequence. Relationships of topography (elevation/aspect) to daily and seasonal temperatures are shown. Tests of the PRISM temperature model are performed at the large watershed scale, revealing magnitudes, modes, and potential sources of bias that could dramatically affect derivative scientific conclusions. A new method of precipitation phase partitioning to detect and quantify frozen precipitation on a sub-daily basis is described. Character of precipitation from sub-daily to annual scales is quantified across all major Great Basin vegetation/elevation zones, and the relationship of elevation to precipitation phase, intensity, and amount is explored. Water-stress responses of Great Basin conifers including Pinus flexilis, Pinus longaeva, and Pinus ponderosa are directly observed, showing potential

  17. Drought responses of conifers in ecotone forests of northern Arizona: tree ring growth and leaf delta13C.

    Adams, Henry D; Kolb, Thomas E


    We sought to understand differences in tree response to meteorological drought among species and soil types at two ecotone forests in northern Arizona, the pinyon-juniper woodland/ponderosa pine ecotone, and the higher elevation, wetter, ponderosa pine/mixed conifer ecotone. We used two approaches that provide different information about drought response: the ratio of standardized radial growth in wet years to dry years (W:D) for the period between years 1950 and 2000 as a measure of growth response to drought, and delta13C in leaves formed in non-drought (2001) and drought (2002) years as a measure of change in water use efficiency (WUE) in response to drought. W:D and leaf delta13C response to drought for Pinus edulis and P. ponderosa did not differ for trees growing on coarse-texture soils derived from cinders compared with finer textured soils derived from flow basalts or sedimentary rocks. P. ponderosa growing near its low elevation range limit at the pinyon-juniper woodland/ponderosa pine ecotone had a greater growth response to drought (higher W:D) and a larger increase in WUE in response to drought than co-occurring P. edulis growing near its high elevation range limit. P. flexilis and Pseudotsuga menziesii growing near their low elevation range limit at the ponderosa pine/mixed conifer ecotone had a larger growth response to drought than co-occurring P. ponderosa growing near its high elevation range limit. Increases in WUE in response to drought were similar for all species at the ponderosa pine/mixed conifer ecotone. Low elevation populations of P. ponderosa had greater growth response to drought than high-elevation populations, whereas populations had a similar increase in WUE in response to drought. Our findings of different responses to drought among co-occurring tree species and between low- and high-elevation populations are interpreted in the context of drought impacts on montane coniferous forests of the southwestern USA.

  18. Vegetation of Lacassine National Wildlife Refuge, Louisiana-Recent plant communities with comparison to a three-decade-old survey

    Howard, Rebecca J.; Michot, Thomas C.; Allain, Larry


    Shifts in plant community composition and structure can affect the quality of habitat for wildlife species. Lacassine National Wildlife Refuge in southwestern Louisiana was established in 1937 with a primary goal of providing habitat for wintering waterfowl species. A large freshwater impoundment constructed on the refuge to improve waterfowl habitat value was completed in 1943. About 10 years after construction was completed, staff at the refuge became concerned that emergent vegetation cover was increasing in the impoundment over time while open water areas, which are critical as foraging and resting areas for waterfowl, were decreasing. To document vegetation change over time, we collected information on plant community species composition for comparison to similar data collected in 1973. A total of 84 sampling plots was established in 2006 within the impoundment to coincide as closely as possible to plots sampled in the earlier study. Plant species composition and cover were recorded at each plot in the summers of 2006 and 2007. Change between sampling events separated by more than three decades was determined by comparing the frequency of occurrence of 20 species identified in 1973 to their frequency in 2006 and 2007. Interannual variation was determined by comparing plot data between 2006 and 2007. In plots dominated by emergent vegetation, it was found that Bacopa caroliniana, Eleocharis equisetoides, Leersia hexandra, Panicum hemitomon, and Sagittaria lancifolia were significantly less frequent in 2006 and 2007 than in 1973. The frequency of Brasenia schreberi, Cabomba caroliniana, Nitella gracilis, and Nymphoides aquatica was significantly lower in 2006 and 2007 than in 1973 in plots dominated by floating-leaved plants, submersed plants, or open water. In 2007, Hydrocotyle sp. and Sacciolepis striata were more frequent than in 1973 in emergent vegetation plots, and Utricularia sp. was more frequent in submersed or open-water plots. We documented

  19. Flora ficológica da região sublitorânea rasa de costões rochosos do Núcleo Picinguaba, Parque Estadual da Serra do Mar, Ubatuba, São Paulo Phycological flora from the shallow sublittoral zone of the rocky shores of Serra do Mar State Park, Ubatuba, São Paulo

    Gisa Eneida Marques Machado


    Full Text Available Em unidades de conservação da zona costeira, o conhecimento das macroalgas marinhas é essencial para monitoramento e manejo. Para o Núcleo Picinguaba do Parque Estadual da Serra do Mar (PESM, Ubatuba, norte do Estado de São Paulo, estudos pretéritos realizados na Enseada da Fazenda listam espécies de macroalgas, coletadas em costões rochosos e manguezais. O presente estudo visou complementar o levantamento taxonômico da flora ficológica marinha do Núcleo Picinguaba, avaliando também a adequação da metodologia para amostragens de suas comunidades de costões rochosos. Foram selecionados 13 pontos de coleta, entre a Ponta da Almada e a Ponta do Cambury, área de maior interferência antropogênica na zona costeira do PESM. No verão de 2007, foram efetuadas coletas de macroalgas, desde a franja da região sublitorânea até o limite do substrato rochoso com a areia. Para uniformizar o esforço amostral, estas buscas foram efetuadas, em cada ponto de coleta, pelo mesmo especialista, durante uma hora de mergulho em apnéia, em uma extensão horizontal do costão rochoso de cerca de 20 m. Foram identificados 128 táxons de categoria infragenérica (80 Rhodophyta, 22 Ochrophyta e 26 Chlorophyta. Callithamniella flexilis Baardseth, Cryptonemia seminervis (C. Agardh J. Agardh, Cladophora pseudorupestris C. Hoek e Cladophora cf. pygmaea Reinke são ocorrências novas para o litoral do Estado de São Paulo, tendo sido descritas e ilustradas. Foram acrescentadas 64 espécies de macroalgas para os costões rochosos do PESM. O esforço amostral foi considerado adequado, resultando na identificação de número de espécies de macroalgas similar ao de outros estudos realizados no litoral norte do estado de São Paulo e no extremo sul do estado do Rio de Janeiro. Para o monitoramento da zona costeira desta unidade de conservação, recomenda-se o levantamento taxonômico das macroalgas dos costões rochosos de modo continuado, durante o per

  20. Why Seedlings Die: Linking Carbon and Water Limitations to Mechanisms of Mortality During Establishment in Conifer Seedlings

    Reinhardt, K.; Germino, M. J.; Kueppers, L. M.; Mitton, J.; Castanha, C.


    BACKGROUND Recent ecophysiological studies aimed at explaining adult tree mortality during drought have examined the carbon (C)-exhaustion compared to the hydraulic-failure hypotheses for death. Prolonged drought leads to durations of stomatal closure (and thus limited C gain), which could result in long periods of negative C balance and fatal reductions in whole-plant C reserves (i.e., available non-structural carbohydrates ["NSC"]). Alternatively, C reserves may not decrease much but could become increasingly inaccessible to sink tissues in long dry-periods due to impediments to translocation of photosynthate (e.g., through disruption of hydrostatic pressure flow in phloem). As C reserves decline or become inaccessible, continued maintenance respiration has been hypothesized to lead to exhaustion of NSC after extended durations of drought, especially in isohydric plant species. On the other hand, hydraulic failure (e.g., catastrophic xylem embolisms) during drought may be the proximate cause of death, occurring before true C starvation occurs. Few studies have investigated specifically the mechanism(s) of tree death, and no published studies that we know of have quantified changes in NSC during mortality. EXPERIMENTAL DESIGN AND HYPOTHESES We conducted two studies that investigated whole-tree and tissue-specific C relations (photosynthetic C gain, respiration, dry-mass gain, and NSC pools) in Pinus flexilis seedlings during the initial establishment phase, which is characterized by progressive drought during summer. We measured survival, growth and biomass allocation, and C-balance physiology (photosynthetic C-gain and chlorophyll fluorescence, respiration C-use, and NSC concentrations) from germination to mortality. We hypothesized that 1) stomatal and biochemical limitations to C gain would constrain seedling survival (through inadequate seasonal C-balance), as has been shown for conifer seedlings near alpine treeline; 2) hydraulic constraints (embolisms and

  1. Comparison of the hydrogeology and water quality of a ground-water augmented lake with two non-augmented lakes in northwest Hillsborough County, Florida

    Metz, Patricia A.; Sacks, Laura A.


    lakes, which is additional evidence of the limited confinement at Round Lake. A comparison of the water quality and lake-bottom sediments at the three lakes indicate that Round Lake is strongly influenced by the addition of large quantities of calcium-bicarbonate enriched augmentation water. Round Lake had higher alkalinity, pH, calcium and dissolved oxygen concentrations, specific conductance, and water clarity than the two non-augmented lakes. Round Lake was generally saturated to supersaturated with respect to calcite, but was undersaturated when augmentation was low and after high rainfall periods. Calcium carbonate has accumulated in the lake sediments from calcite precipitation, from macrophytes such as Nitella sp., and from the deposition of carbonate-rich mollusk shells, such as Planerbella sp., both of which thrive in the high alkalinity lake water. Lake-bottom sediments and aquatic biota at Round Lake had some of the highest radium-226 activity levels measured in a Florida lake. The high radium-226 levels (27 disintegrations per minute per dry mass) can be atrributed to augmenting the lake with ground water from the Upper Floridan aquifer. Although the ground water has relatively low levels of radium-226 (5.8 disintegrations per minute per liter), the large volumes of ground water added to the lake for more than 30 years have caused radium-226 to accumulate in the sediments and lake biota.The Round Lake basin had higher calcium and bicarbonate concentrations in the surficial aquifer than at the non-augmented lakes, which indicates the lateral leakage of calcium-bicarbonate enriched lake water into the surficial aquifer. Deuterium and oxygen-18 data indicated that water in well nests near the lake consists of as much as 100 percent lake leakage, and water from the augmentation well had a high percentage of recirculated lake water (between 59 and 73 percent lake leakage). The ground water surrounding Round Lake was undersaturated with respect to calcite