hh.sePublikasjoner
Endre søk
Begrens søket
1 - 5 of 5
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Vretare, Viveka
    et al.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Weisner, Stefan E.B.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Strand, John A.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Graneli, Wilhelm
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Phenotypic plasticity in Phragmites australis as a functional response to water depth2001Inngår i: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522, Vol. 69, nr 2-4, s. 127-145Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have performed investigations to see if the emergent macrophyte Phragmites australia (Cav.) Trin. ex Steud. exhibits phenotypic plasticity as a response to water depth and if such responses in biomass allocation pattern and morphology are functional responses, improving the performance of the plant. In greenhouse experiments plants were grown in deep or shallow water to evaluate plastic responses. Allometric methods were used to handle effects caused by size differences between treatments. To evaluate if phenotypic responses to water depth are functional, the relative growth rate (RGR) of plants acclimatised to shallow or deep water, respectively, were compared in deep water, and the growth of plants in fluctuating and constant water level were compared. When grown in deep (70 or 75 cm), compared to shallow (20 or 5 cm) water, plants allocated proportionally less to below-ground weight, made proportionally fewer but taller stems, and had rhizomes that were situated more superficially in the substrate. Plants acclimatised to shallow water had lower RGR than plants acclimatised to deep water, when they were grown in deep water, and plants in constant water depth (40 cm) grew faster than plants in fluctuating water depth (15/65 cm). In an additional field study, the rhizomes were situated superficially in the sediment in deep, compared to shallow water. We have shown that P. australis acclimatises to deep water with phenotypic plasticity through allocating more resources to stem weight, and also by producing fewer but taller stems, which will act to maintain a positive carbon balance and an effective gas exchange between aerial and below-ground parts. Furthermore, the decreased proportional allocation to below-ground parts probably results in decreased nutrient absorption, decreased anchorage in the sediment and decreased carbohydrate reserves. Thus, in deep water, plants have an increased risk of becoming uprooted and experience decreased growth and dispersal rates. (C) 2001 Elsevier Science B.V. All rights reserved.

  • 2.
    Weisner, Stefan E.B.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Factors affecting the internal oxygen supply of Phragmites australis (Cav.) Trin. ex Steudel in situ1988Inngår i: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522, Vol. 31, nr 3-4, s. 329-335Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oxygen concentration in basal stems of Phragmites australis (Cav.) Trin. ex Steudel was measured in situ, in monospecific stands. The mean O2 concentration in basal stems, and mean shoot length above water, decreased in deeper water. Oxygen concentration in basal stems was correlated to shoot length above water at a given water depth, and the mean O2 concentration in basal stems of shoots with similar length above water decreased in deeper water. The results suggest that O2 transport from shoots to below-ground parts is restricted in deep water by: (1) small shoot length above water; (2) long O2 transport distance. No influence of substrate redox potential on O2concentration in basal stems was found. © Copyright 1988 Elsevier B.V.

  • 3.
    Weisner, Stefan E.B.
    et al.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Ekstam, Börje
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Influence of germination time on juvenile performance of Phragmites australis on temporarily exposed bottoms – implications for the colonization of lake beds1993Inngår i: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522, Vol. 45, nr 2-3, s. 107-118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three cohorts of seedlings of Phragmites australis (Cav.) Trin ex Steud., germinated in May, June and July, were allowed to grow in shallow water (depth 5 cm or less) in southern Sweden. In the autumn, size parameters were measured on the plants. In the second year, the water level was raised to 0.8 m and emergence of shoots, plant survival and size parameters were recorded. The mean plant weight by the end of the first year differed markedly between cohorts. Rhizome biomass showed a relationship of 700:70:1 between the May, June and July cohorts. In the second year, rate of emergence above the water surface, and maximum height of plants that did not reach the water surface, was positively related to the size (mass) the plants had achieved after the first year. Only plants that emerged above the water surface survived the second summer, resulting in survival rates for the May, June and July cohorts of 90%, 68% and 0%, respectively. The rhizome weight of the smallest survivors had decreased after the second summer compared with values after the first summer. Hence, they were not capable of ‘reloading’ their rhizomes during the second year. In a temperate climate, the size of juvenile plants after the first year, which is strongly dependent on early germination on exposed bottoms (i.e. bottoms without standing water), determines their water depth tolerance during the second year. The timing and duration of exposure, as well as the subsequent depth of re-flooding, are all of fundamental importance for successful ‘lakeward’ seedling expansion of P. australis.

  • 4.
    Weisner, Stefan E.B.
    et al.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Graneli, Wilhelm
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Influence of substrate conditions on the growth of Phragmites australis after a reduction in oxygen transport to below-ground parts1989Inngår i: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522, Vol. 35, nr 1, s. 71-80Artikkel i tidsskrift (Fagfellevurdert)
  • 5.
    Weisner, Stefan E.B.
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Miao, Shi Li
    Everglades Department, South Florida Water Management District, West Palm Beach, USA .
    Use of morphological variability in Cladium jamaicense and Typha domingensis to understand vegetation changes in an Everglades marsh2004Inngår i: Aquatic Botany, ISSN 0304-3770, E-ISSN 1879-1522, Vol. 78, nr 4, s. 319-335Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The northern Florida Everglades have experienced an expansion of cattail (Typha domingensis) and a decrease of sawgrass (Cladium jamaicense) communities. In this study, spatial and temporal within-species variability in plant performance were used to explore the mechanisms causing the distributional changes of cattail and sawgrass. Biomass, shoot density, plant weight, shoot height, and biomass allocation to different plant components (leaves, shoot bases, roots and rhizomes), were sampled in cattail and sawgrass stands along a nutrient gradient within water conservation area 2A during two sequential years with different water level conditions. The shoot height–leaf weight relationships were analysed with allometric methods. Sawgrass exhibited responses to nutrient limitation that resembled functional responses to deep water, indicating that impact of deep water was stronger when plant growth was limited by nutrient deficiency. In cattail, responses along the nutrient gradient were less pronounced. Plant responses along the nutrient gradient differed between years. This was most evident in sawgrass, showing that this species was more affected by water depth than cattail. Responses in sawgrass suggested that this species had to sacrifice important plant functions in deep water at low-nutrient sites. The results in this study emphasise that, to preserve and restore sawgrass communities, lower water levels are required. For cattail, a combination of low phosphorus availability and disturbances (such as extended droughts and outbreaks of herbivores) is needed to stop the ongoing expansion. Management of these ecosystems must consider the relative roles of water level, nutrient enrichment, and disturbances, for vegetation development.

1 - 5 of 5
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf