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  • 1.
    Joelsson, Arne
    et al.
    County Administrative Board of Halland, Sweden.
    Erlandsson, Gert
    Regional Development Council, Halmstad, Sweden.
    Feuerbach, Peter
    Rural Economy and Agricultural Society of Halland, Eldsberga, Sweden.
    Hansson, Anna
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Henriksson, Annika
    County Administrative Board of Halland, Sweden.
    Kindt, Torsten
    Municipality of Laholm, Sweden.
    Kling, Johan
    County Administrative Board of Halland, Sweden.
    Strand, John A.
    Rural Economy and Agricultural Society of Halland, Eldsberga, Sweden.
    Svensson, Jonas
    County Administrative Board of Halland, Sweden.
    Tollebäck, Erika
    County Administrative Board of Halland, Sweden.
    Vartia, Katarina
    County Administrative Board of Halland, Sweden.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    The Aquarius approach on mitigation of phosphorus losses2010Inngår i: 6th International Phosphorus Workshop (IPW6): Towards a sustainable control of diffuse P loss: risk, monitoring, modelling, and mitigation options, 2010, s. 164-Konferansepaper (Annet vitenskapelig)
  • 2.
    Strand, John A.
    et al.
    Hushållningssällskapet i Halland.
    Feuerbach, Peter
    Hushållningssällskapet i Halland.
    Svensson, Jonas
    Länsstyrelsen i Hallands län.
    Vartia, Katarina
    Länsstyrelsen i Hallands län.
    Kindt, Torsten
    Laholms kommun.
    Kling, Johan
    Havs- och vattenmyndigheten.
    Henriksson, Annika
    Agellus.
    Joelsson, Arne
    Länsstyrelsen i Hallands län.
    Edenman, Gunnar
    Aquarius-projektet.
    Hansson, Anna
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Erlandsson, Gert
    Region Halland.
    Markägare som vattenförvaltare i ett förändrat klimat2012Rapport (Annet vitenskapelig)
  • 3.
    Strand, John A.
    et al.
    Hushållningssällskapet Halland.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Kävlingeåprojektet – utvärdering av etapp I-III: Rapport på uppdrag av Programberedningen för Kävlingeåprojektet2010Rapport (Annet vitenskapelig)
  • 4.
    Strand, John A.
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Vegetationsförändringar i Vänern - steg två: Projektplan för att utreda orsaken till igenbuskningen av skär och stränder samt dynamik hos vattenvegetationen2002Rapport (Annet vitenskapelig)
  • 5.
    Strand, John A.
    et al.
    Limnology, Lund University, Lund, Sweden.
    Weisner, Stefan
    Limnology, Lund University, Lund, Sweden.
    Wave exposure related growth of epiphyton: Implications for the distribution of submerged macrophytes in eutrophic lakes1996Inngår i: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 325, nr 2, s. 113-119Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The distribution of submerged macrophytes in eutrophic lakes has been found to be skewed towards sites with intermediate exposure to waves. Low submerged macrophyte biomass at exposed sites has been explained by, for instance, physical damage from waves. The aim of this study was to investigate if lower biomass at sheltered sites compared to sites with intermediate exposure to waves can be caused by competition from epiphyton. Investigations were performed in eutrophic lakes in southern Sweden. Samples of submerged macrophytes and epiphytic algae on the macrophytes were taken along a wave exposure gradient. The amount of epiphyton (AFDW) per macrophyte biomass decreased with increased exposure. Biomass of submerged macrophytes, on the other hand, increased with increased exposure until a relatively abrupt disappearance of submerged vegetation occurred at high exposures. Production of epiphytic algae was monitored on artificial substrates from June to September at a sheltered and an exposed site in three lakes. It was higher at sheltered sites compared with exposed sites. We suggest that epiphytic algae may be an important factor in limiting the distribution of submerged macrophytes at sheltered sites in eutrophic lakes.

  • 6.
    Strand, John A.
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Weisner, Stefan E. B.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Combating eutrophication of the sea and enhancing biodiversity of the agricultural landscape: experiences from wetland creation in Sweden2011Konferansepaper (Annet vitenskapelig)
  • 7.
    Strand, John A.
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan E B
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Effects of wetland construction on nitrogen transport and species richness in the agricultural landscape – experiences from Sweden2013Inngår i: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 56, s. 14-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Constructed wetlands, have been used to decrease nitrogen transport from agricultural catchments to the coast of Sweden, while simultaneously contributing to increased species richness in the landscape. The purpose of this paper is to compile and evaluate data that have been produced in Sweden during some 20 years of using constructed wetlands as an environmental tool. To evaluate effects of different stated objectives for constructed wetlands within different national support systems we focus on nitrogen removal and bird and amphibian species richness. Continuous automatic water sampling for nitrogen removal measurements, during 1.5 to 10 years, has been performed in 7 constructed wetlands located in agricultural catchments in southern Sweden. Nitrogen removal per wetland area varied between wetlands but the results imply that an annual removal of at least 1000. kg. N per ha wetland area can be achieved in individual wetlands. Data from the long-term monitoring of the 7 wetlands, together with nitrogen removal data in the literature, were used to model >150 randomly selected constructed wetlands. According to the modeling, the nitrogen removal per created wetland area varied markedly between different wetland creation programs and was generally considerably lower compared to what can be achieved in individual wetlands. Cost-efficiency of nitrogen removal in wetland creation programs can be increased considerably with improved planning and if other desired benefits (e.g. species richness) contribute to share the costs for wetland creation. The effects of constructed wetlands in Sweden on species number and populations of wetland birds and amphibians were large enough to positively affect the occurrence of species in the national red list, i.e. on a national population level. Species richness of wetland breeding birds in the constructed wetlands were relatively stable after 13 years, but different functional groups had very different succession pattern. The mean maximum breeding bird species number in the wetlands occurred after 3.8 years. Wetland birds and amphibians colonized constructed wetlands irrespective of the original objective of the wetland (nitrogen removal or biodiversity). However, some amphibian species showed preference for biodiversity wetlands. There were clear effects of wetland construction on the regional populations of non-wetland bird species. The maximum species number for a given wetland size was found to be higher than previously reported. The analyses show that wetland construction can be a cost effective method for decreasing transport of diffuse pollution from arable land, and that the wetlands are important for the species numbers and population sizes on all spatial scales. © 2013 Elsevier B.V.

  • 8.
    Strand, John A.
    et al.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Weisner, Stefan E.B.
    Limnology, Department of Ecology, Lund University, Lund, Sweden .
    Dynamics of submerged macrophyte populations in response to biomanipulation2001Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 46, nr 10, s. 1397-1408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. A 6-year study (1992-97) of changes in submerged vegetation after biomanipulation was carried out in the eutrophicated Lake Finjasjon, Southern Sweden. Ten sites around the lake were revisited each year. At each site five samples of above-ground biomass were taken at 10 cm water depth intervals. An investigation of the seed bank at the 10 sites, and a grazing experiment where birds and large fish were excluded was also conducted. 2. Between 1992 and 1996, in shallow areas (water depth < 3 m), vegetation cover 2 increased from < 3 to 75% and above-ground biomass from < 1 to 100 g DW m(-2). Mean outer water depth increased from 0.3 to 2.5 m. Elodea canadensis and Myriophyllum spicatum accounted for > 95% of the increase in biomass and plant cover. The following year (1997), however, cover and above-ground biomass decreased, mainly attributable to the total disappearance of E. canadensis. Secchi depth increased after biomanipulation until 1996, but decreased again in 1997. 3. Total and mean number of submerged species increased after biomanipulation, probably as a result of the improved light climate. However, after the initial increase in species number there was a decrease during the following years, possibly attributed to competition from the rapidly expanding E. canadensis and M. spicatum. The lack of increase in species number after the disappearance of E. canadensis in 1997 implies that other factors also affected species richness. 4. A viable seed bank was not necessary for a rapid recolonization of submerged macrophytes, nor did grazing by waterfowl or fish delay the re-colonization of submerged macrophytes. 5. Submerged macrophytes are capable of rapid recolonization if conditions improve, even in large lakes such as Finjasjon (11 km(2)). Species that spread by fragments will increase rapidly and probably outcompete other species. 6. The results indicate that after the initial Secchi depth increase, probably caused by high zooplankton densities, submerged vegetation further improved the light climate. The decrease in macrophyte biomass in 1997 may have caused the observed increase in phosphorus and chlorophyll a, and the decrease in Secchi depth. We suggest that nutrient competition from periphyton, attached to the macrophytes, may be an important factor in limiting phytoplankton production, although other factors (e.g. zooplankton grazing) are also of importance, especially as triggers for the shift to a clear-water state.

  • 9.
    Strand, John A.
    et al.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Weisner, Stefan E.B.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Morphological plastic responses to water depth and wave exposure in an aquatic plant (Myriophyllum spicatum)2001Inngår i: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 89, nr 2, s. 166-175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1 We investigated morphological responses of the submerged macrophyte Myriophyllum spicatum L. to water depth and wave exposure when grown in the same substrate at two sites in two eutrophic lakes. Periphyton production was 4-8 times higher at sheltered than at wave-exposed sites and its influence was further investigated in a glasshouse experiment. Morphological responses in both experiments were compared by allometric analyses, with shoot weight as covariate. 2 In the field study, plants shoots exhibited similar responses (increased plant height and branch length, and decreased branch number) to sheltered conditions as to deep water. The partitioning between above- and below-ground biomass however, differed, with below-ground decreasing with an increasing water depth, but increasing or remaining unaffected at sheltered compared with exposed conditions. 3 In the glasshouse experiment, plant responses to water depth were similar to those in the field study. Furthermore, plant height increased when plants were overgrown with periphyton. 4 High production of periphytic algae at sheltered sites appears to cause light limitation of macrophytes. However, other factors such as nutrient uptake also appears to determine morphological responses. At sheltered sites, where leaf nutrient uptake is reduced by abundant periphyton and thick boundary layers, plants allocate more biomass to roots. At deep and wave-exposed sites, the absence of periphyton allows plants to take up nutrients through their leaves and allocation of biomass to shoots increases photosynthesis. 5 Overall, relative allocation to shoot and root biomass appears to be primarily controlled by nutrient availability, whereas allocation of available shoot biomass to particular structures is controlled by light availability.

  • 10.
    Strand, John A.
    et al.
    The Rural Economy and Agricultural Society of Halland, Lilla Boslid, Eldsberga, Sweden .
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Phenotypic plasticity – contrasting species-specific traits induced by identical environmental constraints2004Inngår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 163, nr 3, s. 449-451Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Can it be assumed that a specific environmental constraint imposed on different species leads to a convergence in, for example, morphology? A phenotype expressed in response to external stimuli (e.g. size-reduction in response to mechanical stress) should be adaptive regardless of species – this is largely intuitive, but has been poorly studied. In this issue (pp. 651–660), Puijalon & Bornette reveal exciting new data that suggest that phenotypic plastic responses to identical environmental constraints may indeed be species-specific (Puijalon & Bornette, 2004).

  • 11.
    Svensson, Jonas M.
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Strand, John A.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Sahlén, Göran
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Weisner, Stefan E.B.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Rikare mångfald och mindre kväve: Utvärdering av våtmarker skapade med stöd av lokala investeringsprogram och landsbygdsutvecklingsstöd2004Bok (Annet vitenskapelig)
    Abstract [sv]

    På uppdrag av Naturvårdsverket och Jordbruksverket har Våtmarkscentrum, Högskolan i Halmstad, utvärderat svenska våtmarker anlagda med landsbygdsutvecklingsstöd, LBU-stöd (Miva, projektstöd och Lmiva utan projektstöd) respektive våtmarker anlagda inom lokala investeringsprogram (LIP) avseende näringsretention och biologisk mångfald. Resultaten från utvärderingen redovisas separat för de fyra olika grupperna/kategorierna av anlagda våtmarker enligt nedan (fetstil anger kategorihänvisning i text, tabeller och figurer):

    • Våtmarker anlagda med anläggningsstöd inom Lokala investeringsprogram 1998 - 2002, LIP.

    • Våtmarker anlagda med anläggningsstöd inom LBU-projektstöd (dessa våtmarker får vanligen även skötselstöd, Lmiva), 2000 - 2002.

    • Våtmarker anlagda 1996-1999, utan anläggningsstöd men med skötselstöd (Miljöstöd), Miva.

    • Våtmarker anlagda från år 2000 - , utan anläggningsstöd men med skötselstöd (LBU-våtmarker som endast får skötselersättning), Lmiva.

    Syftet har främst varit att utvärdera och jämföra hur våtmarksanläggning inom olika stödformer har bidragit till minskad övergödning och ökad biologisk mångfald. Syftet har alltså inte varit att utvärdera enskilda våtmarker utan att ge en helhetsbild för olika stödformer och regioner. Därför har det varit nödvändigt att basera utvärderingen på data för ett stort antal våtmarker. Detta innebär att utförliga mätningar ej kunnat genomföras inom de enskilda objekten. Närsaltsretention har därför beräknats baserat på modeller och biologisk mångfald har undersökts genom att trollsländor använts som indikatorgrupp.

    Inom uppdraget har, med jordbruksstöd, registrerats information om totalt 908 våtmarksobjekt om totalt 2860 ha ersatt yta fördelat på 1815 ha Miva, 920 ha projektstöd och 125 ha Lmiva utan projektstöd. Totalt registrerade våtmarker med stöd från LIP är 274 st, omfattande 439 ha.

    Kompletterande fältstudier har utförts i drygt 100 st våtmarker. Främst är det resultaten från dessa våtmarker som sammanfattas nedan...

  • 12.
    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.

  • 13.
    Weisner, Stefan E. B.
    et al.
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, Bio- och miljösystemforskning (BLESS), Miljövetenskap, Våtmarkscentrum.
    Strand, John A.
    Rural economy and agricultural society, Lilla Böslid, Eldsberga.
    Ecology and management of plants in aquatic ecosystems2002Inngår i: Handbook of ecological restoration: Vol. 1, Principles of restoration / [ed] Martin R. Perrow, Anthony J. Davy, Cambridge: Cambridge University Press , 2002, s. 242-256Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The central role of macrophytes for the functioning of aquatic systems means that the most effective way to manage these systems is often through vegetation management. For this we need to understand the mechanisms regulating vegetation distribution. Submerged macrophyte distribution is mainly related to water depth, water transparency and epiphytic growth. The distribution of emergent vegetation can largely be predicted from water depth and substrate characteristics. Also, in both submerged and emergent macrophytes, the effects on the vegetation of grazing can be dramatic. Management should aim at providing environmental conditions favouring the desired ecosystem state, rather than methods directly aimed at the vegetation. For example, the best method for promoting establishment of emergent vegetation is often lowering of the water level. To establish submerged vegetation, water transparency can be increased through biomanipulation (the removal of zooplanktivorous fish leading to increased zooplankton grazing pressure on phytoplankton). Changes in water depth and introduction of grazers are often effective measures to control growth of aquatic weeds.

  • 14.
    Weisner, Stefan E.B.
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Strand, John A.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Sahlén, Göran
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Thiere, Geraldine
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Ehde, Per Magnus
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Svensson, Jonas M.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Combating eutrophication and biodiversity loss in Sweden: importance of constructed wetlands in the agricultural landscape2007Inngår i: Multifunctions of wetland systems, Padua: PAN , 2007, s. 60-61Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The results of this evaluation show that constructed wetlands in the agricultural landscape are capable of a substantial reduction of the nutrient transport to downstream recipients, but only if properly located. These wetlands will also contribute to an increased biodiversity even if not planned primarily for this purpose. The use of wetlands for multiple functions needs to be developed to motivate large-scale wetland construction.

  • 15.
    Weisner, Stefan E.B.
    et al.
    Limnology, Lund University, Lund, Sweden .
    Strand, John A.
    Limnology, Lund University, Lund, Sweden .
    Sandsten, Håkan
    Limnology, Lund University, Lund, Sweden .
    Mechanisms regulating abundance of submerged vegetation in shallow eutrophic lakes1997Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 109, nr 4, s. 592-599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Shallow eutrophic lakes tend to be either in a turbid state dominated by phytoplankton or in a clear-water state dominated by submerged macrovegetation. Recent studies suggest that the low water turbidity in the clear-water state is maintained through direct and in-direct effects of the submerged vegetation. This study examined what mechanisms may cause a recession of the submerged vegetation in the clear-water state, and thereby a switch to the turbid state. The spatial distribution of submerged vegetation biomass was investigated in two shallow eutrophic lakes in the clear-water state in southern Sweden. Biomass of submerged vegetation was positively correlated with water depth and wave exposure, which also were mutually correlated, suggesting that mechanisms hampering submerged vegetation were strongest at shallow and/or sheltered locations. The growth of Myriophyllum spicatum, planted in the same substrate and at the same water depth, was compared between sheltered and wave exposed sites in two lakes. After 6 weeks the plants were significantly smaller at the sheltered sites, where periphyton production was about 5 times higher than at the exposed sites. Exclosure experiments were conducted to evaluate the effects of waterfowl grazing on macrophyte biomass. Potamogeton pectinatus growth was decreased by grazing, whereas M. spicatum was not affected. The effects were greater at a sheltered than at a wave-exposed site, and also negatively related to distance from the reed belt. These results suggest that competition from epiphytes and waterfowl grazing hamper the development of submerged vegetation at sheltered and/or shallow locations. An increased strength of these mechanisms may cause a recession of submerged vegetation in shallow eutrophic lakes in the clear-water state and thereby a switch to the turbid state.

  • 16.
    Weisner, Stefan
    et al.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Strand, John A.
    Limnology, Department of Ecology, Lund University, Lund, Sweden.
    Rhizome architecture in Phragmites australis in relation to water depth: Implications for within-plant oxygen transport distances1996Inngår i: Folia Geobotanica, ISSN 1211-9520, E-ISSN 1874-9348, Vol. 31, nr 1, s. 91-97Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phragmites australis (CAV.) TRlN. ex STEUD. is a perennial plant, largely relying on its rhizomes for resource storage, spreading and anchorage in the substrate. Vertical distribution and length of horizontal rhizomes of Phragmites australis were investigated at the reed bed edge in a lake in southern Sweden. In deep water, horizontal rhizomes were relatively short and superficially situated in the substrate. It is hypothesised that this is an adaptation to water depth by keeping O-2-transport distances through shoots and rhizomes as short as possible. In shallow water, P. australis rhizomes generally penetrated deeply into the substrate, probably improving anchorage and nutrient uptake possibilities. Further, horizontal rhizomes were longer in shallow water, which may increase the rate of vegetative spread. Because of these changes in rhizome architecture, "critical within-plant oxygen transport distances" did not change with water depth. This indicates that P. australis maximises the extension of its rhizomes in relation to spatial differences in water depth. This may limit the ability of P. australis to tolerate sudden temporal increases in water depth or eutrophication.

  • 17.
    Weisner, Stefan
    et al.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Svensson, Jonas M.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Strand, John A.
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Svengren, Henrik
    Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), Bio- och miljösystemforskning (BLESS), Våtmarkscentrum.
    Combating eutrophication in Sweden: Importance of constructed wetlands in agricultural landscapes2005Inngår i: Is living water possible in agricultural areas?: Seminar on ecological engineering tools to combat diffuse pollution: June 20-22, 2005, Norway: Proceedings from NJF seminar no. 374 / [ed] Bent C. Braskerud, Ås, Norway: Jordforsk , 2005, s. 66-69Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The Wetland Centre at Halmstad University was commissioned by the Swedish Environmental Protection Agency and the Swedish Board of Agriculture to evaluate the effects of artificially created wetlands in Sweden between the years 1996 and 2002 with regard to nutrient retention and biodiversity. The creation of these wetlands has been financed either by Rural Development Support (RDS: Miva, Project support or Lmiva without Project support) or by Local Investment Programmes (LIP). The results are presented separately for the four different categories of constructed wetlands:

    • Constructed wetlands financed by LIP (Local Investment Programmes) (1998-2002).
    • Constructed wetlands financed by PS (Project Support) (2000-2002).
    • Constructed wetlands financed by Miva (Restoration and Establishment of Wetlands and Ponds on Arable land and Semi-natural Grazing land) (1996-1999).
    • Constructed wetlands financed by Lmiva (RDS wetlands that only get management support) (2000-2002).

    The main purpose of this study has been to evaluate the extent to which wetlands created by means of these different support systems have contributed to reduced eutrophication and increased biodiversity. The purpose has not been to evaluate individual wetlands but to give an overview of the differences in efficiency between the various support systems and, to some extent, the difference in results between various geographical regions within Sweden. It has therefore been necessary to include a large number of wetlands in the evaluation, which means that extensive field sampling in the individual wetlands has not been possible. The estimates concerning nutrient retention has therefore been based on modelling, and the biodiversity has been assessed by using dragonflies (Odonata) as indicator organisms.

    Information on 908 wetlands with a total area of 2860 hectares financed by RDS has been compiled and registered. In terms of area, these wetlands divide into 1815 ha financed by Miva, 920 ha financed by PS and 125 ha by Lmiva. In addition, 274 wetlands created by means of LIP, with a total area of 439 ha, have been registered. Field surveys and sampling has been conducted in more than 100 wetlands randomly selected from this register. It is mainly the results from these selected wetlands that are presented here.

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