| 1. |
- Brink, Ebba, et al.
(författare)
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On the road to research municipalities : Analysing transdisciplinarity in municipal ecosystem services and adaptation planning
- 2018
-
Ingår i: Sustainability Science. - : Springer. - 1862-4065 .- 1862-4057. ; 13:3, s. 765-784
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Tidskriftsartikel (refereegranskat)abstract
- Transdisciplinary research and collaboration is widely acknowledged as a critical success factor for solution- oriented approaches that can tackle complex sustainability challenges, such as biodiversity loss, pollution, and climate-related hazards. In this context, city governments’ engagement in transdisciplinarity is generally seen as a key condition for societal transformation towards sustainability. However, empirical evidence is rare. This paper presents a self-assessment of a joint research project on ecosystem services and climate adaptation planning (ECOSIMP) undertaken by four universities and seven Swedish municipalities. We apply a set of design principles and guiding questions for transdisciplinary sustainability projects and, on this basis, identify key aspects for supporting university–municipality collaboration. We show that: (1) selecting the number and type of project stakeholders requires more explicit consideration of the purpose of societal actors’ participation; (2) concrete, interim benefits for participating practitioners and organisations need to be continuously discussed; (3) promoting the ‘inter’, i.e., interdisciplinary and inter-city learning, can support transdisciplinarity and, ultimately, urban sustainability and long-term change. In this context, we found that design principles for transdisciplinarity have the potential to (4) mitigate project shortcomings, even when transdisciplinarity is not an explicit aim, and (5) address differences and allow new voices to be heard. We propose additional guiding questions to address shortcomings and inspire reflexivity in transdisciplinary projects.
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| 2. |
- Inamdeen, Fainaz, et al.
(författare)
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Local scour in rivers due to bridges and natural features. A case study from Rönne river, Sweden
- 2021
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Ingår i: Vatten: tidskrift för vattenvård /Journal of Water Management and research. - 0042-2886. ; 77:3, s. 143-161
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Bridges are important components in many transportation networks often spanning rivers and other water bodies. The failure of a bridge will cause significant direct and indirect economic losses to society. Scouring of the river bed around bridges is a principal mode of bridge failure typically associated with large floods. The risk of such scour may become higher with the emerging climate change that can induce large floods in a short period of time, significantly changing the river hydraulics. The objective of the present study is to review the significance of different types of riverbed scour with a focus on the fundamental mechanisms and governing parameters controlling bridge scour. The study was conducted in the Rönne River at Ängelholm Municipality because many scour holes were discovered along the river bottom during a high-resolution bathymetric survey. The bathymetric analysis identified 14 major scour holes of between 1.3 and 3.5 m depth from the existing, undisturbed river bed. The investigation revealed that the scour holes originate from bridge, bend, and hard bottom scour. A special analysis of bridge scour was performed using river hydraulic properties obtained through simulations with the one-dimensional hydraulic model HEC RAS. According to these scour simulations, the studied bridges show more potential risk for abutment scour and pier scour than for contraction scour. The bridge Flygarebron shows the highest potential risk for abutment and pier scour, whereas the Kristian II bridge has the highest risk for contraction scour.
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| 3. |
- Kallner Bastviken, Sofia, et al.
(författare)
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Effects of vegetation and hydraulic load on seasonal nitrate removal in treatment wetlands
- 2009
-
Ingår i: Ecological Engineering. - Amsterdam : Elsevier. - 0925-8574 .- 1872-6992. ; 35:5, s. 946-952
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Tidskriftsartikel (refereegranskat)abstract
- Optimising nitrate removal and identifying critical factors for nitrate removal in wetlands is an important environmental task in the effort to achieve better surface water quality. In this study, eighteen free water surface wetlands with similar shape and size (22 m2 each) received groundwater with a high nitrate-N concentration (about 11 mg l−1). The effects of two hydraulic loads, 0.13 m d−1 and 0.39 m d−1, and three vegetation types – emergent, submersed and freely developing vegetation – on the nitrate-N removal were investigated through mass inflow and outflow measurements.No significant difference in nitrate removal between the different hydraulic loads could be detected. Significantly higher area-specific nitrate removal and first-order area-based rate coefficients were found in the basins with emergent vegetation, with no difference between the basins with submersed and freely developing vegetation. The nitrate-N removal increased as the wetlands matured and the vegetation grew denser, emphasizing the role of dense emergent vegetation for nitrate removal at high nitrate concentrations.
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| 4. |
- Mazier, Florence, et al.
(författare)
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Two hundred years of land-use change in the South Swedish Uplands: comparison of historical map-based estimates with a pollen-based reconstruction using the landscape reconstruction algorithm
- 2015
-
Ingår i: Vegetation History and Archaeobotany. - : Springer Science and Business Media LLC. - 0939-6314 .- 1617-6278. ; 24:5, s. 555-570
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Tidskriftsartikel (refereegranskat)abstract
- Long-term records of environmental history at decadal to millennial time-scales enable an assessment of ecosystem variability and responses to past anthropogenic disturbances and are fundamental for the development of environmental management strategies. This study examines the local variability of land-use history in the South Swedish Uplands over the last 200 years based on pollen records from three lake-sediment successions. Temporal changes in the proportional cover of 14 plant taxa were quantified as percentages using the landscape reconstruction algorithm (LRA). The LRA-based estimates of the extent of four land-use categories (cropland, meadows/grassland, wetland, outland/woodland) were compared to corresponding estimates based on historical maps and aerial photographs from ad 1769-1823, 1837-1895, 1946 and 2005. Although the LRA approach tends to overestimate grassland cover by 10-30 % for the two earliest time periods, the reconstructed vegetation composition is generally in good agreement with estimates based on the historical records. Subsequently, the LRA approach was used to reconstruct the 200-year history of local land-use dynamics at 20-year intervals around two small lakes. The qualitative assessment of difference approach, which requires fewer assumptions and parameters than LRA for objective evaluation of between-site differences in plant abundances, provides consistent results in general. Significant differences exist in the land-use history between the sites. Local catchment characteristics, such as soil conditions and wetland cover, appear important for the development of human impact on the landscape. Quantifications of past vegetation dynamics provide information on the amplitude, frequency and duration of the land-use changes and their effects on terrestrial and aquatic ecosystems, and should be taken into account when nature conservation strategies are developed.
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| 5. |
- Milenkovski, Susann, et al.
(författare)
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Composition of denitrifying bacterial enzyme genes nirS, nirK and nosZ in constructed wetlands
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this study the composition of the denitrifying bacterial community among constructed wetlands in agricultural areas was investigated. Thirty-two constructed wetlands located in Southern Sweden were surveyed, and biofilm samples from each were analyzed by applying denaturing gradient gel electrophoresis, to investigate the community composition of the three denitrifying bacterial enzyme genes nirK, nirS and nosZ. The DNA sequences of the enzyme genes were compared to known DNA sequences in GeneBank using BLAST. The results of the denitrifying bacterial enzyme genes indicated that these habitats may harbour a heterogeneous denitrifying bacterial community. Individual analysis of the enzyme genes revealed that nirS was more heterogeneous than both nirK and nosZ. Most sequences from the present study clustered with known sequences from species belonging to the group of α-Proteobacteria, and to a lesser extent with β- Proteobacteria and γ-Proteobacteria, and only nirS clustered with a member of gram-positive bacteria.
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| 6. |
- Milenkovski, S, et al.
(författare)
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Denitrification in constructed wetlands in southern Sweden
- 2007
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Ingår i: 2nd International Symposium on Wetland Pollutant Dynamics and Control - WETPOL 2007. - : Institute of Geography. - 9789949116881 - 9949116880 - 9789949116898 - 9949116899 ; , s. 220-222
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Milenkovski, Susann, et al.
(författare)
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Variation of eubacterial and denitrifying bacterial biofilm communities among constructed wetlands
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Bacteria play important roles in the transformation of nutrients in wetlands, but few studies have examined parameters affecting variation in bacterial community composition between wetlands. We compared the composition of eubacterial and denitrifying bacterial biofilm communities in 32 agricultural constructed wetlands in southern Sweden, and the extent to which wetland environmental parameters could explain the observed variation. Structure and richness of the eubacterial 16S rRNA gene and three denitrifying bacterial enzyme genes (nirK, nirS and nosZ), analysed by molecular fingerprinting methods, varied among the constructed wetlands, which could be partly explained by different environmental parameters. Results from the enzyme gene analyses were also compared to determine whether the practice of using a single denitrifying bacterial gene could characterize the overall community composition of denitrifying bacteria. We found that nirK was more diverse than both nirS and the nosZ, and the band structure and richness of the three genes were not related to the sam environmental parameters. This suggests that using a single enzyme gene may not suffice to characterize the community composition of denitrifying bacteria in constructed agricultural wetlands.
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| 8. |
- Schulz, Ralf, et al.
(författare)
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A combined microcosm and field approach to evaluate the aquatic toxicity of azinphos-methyl to stream communities
- 2002
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Ingår i: Environmental Toxicology and Chemistry. - New York : Pergamon. - 0730-7268 .- 1552-8618. ; 21:10, s. 2172-2178
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated the potential effects of the organophosphate insecticide azinphosmethyl (AZP) in a combined microcosm and field approach. The upper regions of the Lourens River, South Africa, are free of contamination (control site), whereas the subsequent stretches flowing through a 400-ha orchard area receive transient insecticide pollution (e.g., 0.82 μg/L AZP, 344 μg/kg chlorpyrifos) following spray drift and runoff (contaminated site). Stones taken from the control site were transferred to outdoor microcosms (1.5 × 0.2 × 0.2 m), providing 12 core species and approximately 350 individuals per microcosm. Microcosms were contaminated for 1 h with AZP (control, 0.2, 1, 5, and 20 μg/L; three replicates each), and acute effects on survival were evaluated 6 d following exposure. The two strongest treatments (measured concentrations: 19.2 ± 1.0 and 4.9 ± 0.3 μg/L, respectively) resulted in a significantly (analysis of variance) reduced invertebrate density, attributed mainly to various insect taxa, such as Demoreptus sp., Castanophlebia sp., Simuliidae, and Chironomidae. In contrast, Aeshna sp., Dugesia sp., Ceratopogonidae, and Cheumatopsyche sp. were unaffected. In parallel, we conducted a quantitative macroinvertebrate survey at the control site and the contaminated site of the Lourens River after the seasonal pesticide application period. The two sites contained a similar number of species but differed considerably in their species composition and abundances. Five of the eight species that were affected by AZP in the microcosm study occurred in the field at significantly lower densities at the contaminated than at the control site or were absent at the contaminated site. All of the four species that were unaffected in the microcosm occurred at significantly higher densities at the contaminated field site. Only 3 of the 12 species reacted differently in the microcosm and the field study. We conclude that microcosm studies employing a field-relevant design could be linked successfully to field studies and our results suggest that transient pesticide contamination affects the aquatic communities of the Lourens River.
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| 9. |
- Schulz, Ralf, et al.
(författare)
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Fate and Effects of Azinphos-Methyl in a Flow-Through Wetland in South Africa
- 2003
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Ingår i: Environmental Science and Technology. - Washington : American Chemical Society. - 0013-936X .- 1520-5851. ; 37:10, s. 2139-2144
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Tidskriftsartikel (refereegranskat)abstract
- Our knowledge about the effectiveness of constructed wetlands in retaining agricultural nonpoint-source pesticide pollution is limited. A 0.44-ha vegetated wetland built along a tributary of the Lourens River, Western Cape, South Africa, was studied to ascertain the retention, fate, and effects of spray drift-borne azinphos-methyl (AZP). Composite water samples taken at the inlet and outlet during five spray drift trials in summer 2000 and 2001 revealed an overall reduction of AZP levels by 90 ± 1% and a retention of AZP mass by 61 ± 5%. Samples were collected at the inlet, outlet, and four platforms within the wetland to determine the fate and effect of AZP in the wetland after direct spray drift deposition in the tributary 200 m upstream of the inlet. Peak concentrations of AZP decreased, and the duration of exposure increased from inlet (0.73 µg/L; 9 h) via platforms 1 and 4 to outlet (0.08 µg/L; 16 h). AZP sorbed to plants or plant surfaces, leading to a peak concentration of 6.8 µg/kg dw. The living plant biomass accounted for 10.5% of the AZP mass initially retained in the wetland, indicating processes such as volatilization, photolysis, hydrolysis, or metabolic degradation as being very important. AZP was not detected in sediments. Water samples taken along two 10-m transects situated perpendicular to the shore indicated a homogeneous horizontal distribution of the pesticide: 0.23±0.02 and 0.14±0.04 µg/L (n = 5), respectively. Both Copepoda (p = 0.019) and Cladocera (p = 0.027) decreased significantly 6 h postdeposition and remained at reduced densities for at least 7 d. In parallel, the chlorophyll a concentration showed an increase, although not significant, within 6 h of spray deposition. The study highlights the potential of constructed wetlands as a risk-mitigation strategy for spray drift-related pesticide pollution.
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| 10. |
- Thiere, Geraldine
(författare)
-
Biodiversity and ecosystem functioning in created agricultural wetlands
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral dissertation was produced in a cooperation between Halmstad University (Wetland Research Centre, School of Business and Engineering) and Lund University (Limnology & Marine Biology, Department of Ecology).Abstract . Wetland creation at large, regional scales is implemented as a measure to abate the biodiversity loss in agricultural landscapes and the eutrophication of watersheds and coastal areas by non-point source nutrient pollution (mainly nitrogen). The consequences of creating many new wetlands for biodiversity conservation and nutrient reten- tion (ecosystem functioning) in agricultural landscapes are still relatively unknown, both on local (per wetland) and regional (per landscape) scales. In Sweden, wetland creation has progressed already since the 1990s, and by now larger numbers of created wetlands are present, mainly in the intensively farmed landscapes of southwestern Sweden. This thesis aimed to investigate the following aspects in these systems: (i) their large-scale effects on biodiversity, (ii) their functional diversity of bacterial denitrifiers, (iii) the abiotic and biotic influences on wetland ecosystem functioning, (iv) the potential for biodiversity-function links, and (v) the potential for functional links and joint functioning.(i) Created wetlands hosted diverse assemblages of macroinvertebrates and plants. They maintained a similar com- position and diversity as natural ponds in agricultural landscapes. The environmental conditions per wetland did hardly affect macroinvertebrate and plant assemblages, and the prerequisites for nutrient retention did neither. In landscapes were wetland creation efforts had increased the total density of small water bodies by more than 30%, macroinver- tebrate diversity of created wetlands was facilitated on both local and regional scales. (ii) Diverse communities of denitrifying bacteria with the capacity for conducting different denitrification steps (functional types) were present in all investigated wetlands. The richness of denitrifying bacteria communities was affected by nitrate concentration and hydraulic loading rate, which may potentially be relevant for the nitrogen retention function of created wetlands. The diversity across different functional types of bacterial denitrifiers increased with nitrate concentration. (iii) Both abiotic and biotic factors influenced ecosystem functions of created wetlands. Variation in nitrogen retention was associated to nitrate load, but even to vegetation parameters. In wetlands with constant nitrate load, planted emergent vegetation facilitated nitrogen retention compared to other vegetation types. In wetlands with variable loads, nitrogen retention was facilitated if nitrate load was high and many different vegetation types were present; nitrogen load could explain the majority of the variation in nitrogen retention compared to vegetation parameters. Phosporus retention of created wetlands was best explained by vegetation parameters. Litter decomposition was inhibited at high nitrate to phosphorus ratios. Methane production increased with age and decreased with plant cover. (iv) Biodiversity may facilitate wetland ecosystem functions, particularly in dynamic wetland ecosystems. Nitrogen retention increased with vegetation type diversity, phosphorus retention capacity with plant richness, and litter decomposition with macroinvertebrate diversity. (v) Created wetlands have the capacity of sustaining several parallel ecosystem services. Some wetland functions were coupled; nitrogen retention increased with fast litter decomposition. On the other hand, methane emission and nitro- gen retention were independent of each other, as were nitrogen and phosphorus retention.In conclusion, created wetlands have the potential to at least partly abate the lost biodiversity and multifunctionality caused by the past extensive destruction of natural wetlands in agricultural landscapes.
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| 11. |
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| 12. |
- Thiere, Geraldine, et al.
(författare)
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Nitrogen retention versus methane emission : Environmental benefits and risks of large-scale wetland creation
- 2011
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Ingår i: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 37:1, s. 6-15
-
Tidskriftsartikel (refereegranskat)abstract
- Coastal eutrophication by nutrient fluxes from agricultural land to marine recipients is presently combated by measures such as the implementation of watershed-scale wetland creation programs aimed at nitrogen removal. Such created agricultural wetlands – termed ‘nitrogen farming wetlands’ (NFWs) – receive nitrogen (N) loads predominantly as nitrate, facilitating N removal by denitrification. However, the conversion of agricultural soils into waterlogged wetland area is likely to increase climate gas emissions, particularly methane (CH4). There is thus a need to evaluate the benefits and risks of wetland creation at a large, watershed-scale. Here we investigate N retention and CH4 emission originating from watershed-scale wetland creation in South Sweden, the relation between both processes, and how CH4 emission depends on individual wetland parameters. We combine data from intensively studied reference wetlands with an extensive wetland survey to predict N retention and CH4 emission with simple models, to estimate the overall process rates (large-scale effects) as well as spatial variation among individual NFWs. We show that watershed-scale wetland creation serves targeted environmental objectives (N retention), and that CH4 emission is comparably low. Environmental benefit and risk of individual wetlands were not correlated, and may thus be managed independently. High cover of aquatic plants was the most important wetland property that suppressed CH4 net production, potentially facilitating N retention simultaneously. Further, differences between wetlands in water temperature and wetland age seemed to contribute to differences in CH4 net production. The nationally planned wetland creation (12,000 ha) could make a significant contribution to the targeted reduction of N fluxes (up to 27% of the Swedish environmental objective), at an environmental risk equaling 0.04% of the national anthropogenic climate gas emission.
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| 13. |
- Thiere, Geraldine, et al.
(författare)
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Runoff-related agricultural impact in relation to macroinvertebrate communities of the Lourens River, South Africa
- 2004
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Ingår i: Water Research. - Oxford : Pergamon Press. - 0043-1354 .- 1879-2448. ; 38:13, s. 3092-3102
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Tidskriftsartikel (refereegranskat)abstract
- A field study at the Lourens River, South Africa, was undertaken during the pesticide application period between November 2001 and January 2002 in order to investigate the potential relation of agricultural pollution to the aquatic macroinvertebrate fauna. The upper regions of the Lourens River were free of contamination (LR1), whereas subsequent stretches flowing through a 400-ha orchard area (LR2) received transient insecticide peaks. Continuously operating suspended-particle samplers as well as flood samplers operating during runoff events were used to measure pesticide contamination. In addition, various physicochemical and morphological parameters were examined. A survey of the macroinvertebrate communities associated with the rocky substrates was carried out every three weeks. Community indices were calculated using the South African Scoring System (SASS 5) for bioassessment of water quality in rivers.The two sites differed in pesticide pollution as well as in average turbidity levels (LR1 5.5 mg/L; LR2 64.3 mg/L), but were similar in bottom substrate composition and most other abiotic factors. At the downstream site (LR2), pesticide values of 0.05 μg/L azinphos-methyl in water as well as 49 μg/kg azinphos-methyl, 94 μg/kg chlorpyrifos and 122 μg/kg total endosulfan in suspended particles were found during runoff conditions. The macroinvertebrate communities of the two sampling sites were similar in terms of number of total individuals, but differed significantly (ANOVA) in average number of taxa (LR1 11.7, LR2 8.9). Seven out of 17 investigated taxa occurred in significantly reduced numbers or were even absent at the downstream site LR2. The community characteristics determined by SASS 5 showed a significantly less sensitive community structure at the downstream site (TS 41; ASPT 4.6), indicating continuously lower water quality compared to site LR1 (TS 80; ASPT 6.9). It is concluded that the Lourens River macroinvertebrate communities are affected by agricultural pollution, with pesticides and increased turbidity as the most important stressors.
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| 14. |
- Thiere, Geraldine, et al.
(författare)
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Runoff simulation with particle-associated azinphosmethyl in multispecies stream microcosms : implications for the field
- 2004
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Ingår i: Environmental Toxicology and Chemistry. - New York : Pergamon Press. - 0730-7268 .- 1552-8618. ; 23:8, s. 1984-1990
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the acute (5 d) effects of particle-associated azinphosmethyl (AZP) in multispecies microcosms and assessed the results in the context to data obtained from a parallel field study undertaken in the Lourens River, South Africa. A runoff simulation was carried out in stream microcosms containing the macroinvertebrate fauna of an uncontaminated Lourens River site exposed to particle-associated AZP (control and 200, 1,000, 5,000, 20,000 μg/kg; three replicates each) for 1 h. Measured AZP concentrations in filtered microcosm water resulted in the following values: Not detectable (control) and 0.03, 0.2, 1.1, and 6.9 μg/L, respectively. The two highest treatments resulted in significantly (analysis of variance [ANOVA]) reduced total numbers of individuals, while the number of taxa was affected in the 20,000 μg/kg treatment only. A comparison with previous data suggests that observed effects partly resulted from particle-associated AZP. Particularly affected were six out of 14 macroinvertebrate taxa such as mayfly and stonefly taxa. In parallel, the distribution of macroinvertebrates at a pesticide-free and a contaminated stretch of the Lourens River was monitored five times during the spraying season in 2001 and 2002. Out of the 14 core taxa found in the microcosm study as well as in the field approach, 10 showed comparable reactions in the microcosm experiment and in their field distribution; they were either classified as affected or unaffected in both studies. Thus, we conclude that particle-associated AZP has the potential to affect the invertebrate community structure of the Lourens River and that microcosm studies employing field-relevant exposure scenarios may be valuable for a local risk assessment of pesticide-related community disruptions in the Lourens River.
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| 15. |
- Thiere, Geraldine, et al.
(författare)
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Uppföljning och förslag på restaurering av anlagda våtmarker i Kalmar kommun
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Den 30 mars 2012 beviljade Länsstyrelsen i Kalmarbidrag till Kalmar kommun för det lokala vattenvårdsprojektet ”Uppföljning och restaurering av våtmarker i Kalmar kommun”. Projektet genomfördes under perioden 25 mars – 30 november i samarbete med miljöanalytiker Jonas Nilsson vid Havsmiljöinstitutets enhet vid Linnéuniversitetet och våtmarksexpert Geraldine Thiere. Delar av projektet genomfördes som ett examensarbete i miljövetenskap av Jessica Olofsson, Linnéuniversitetet. En bedömning visade att majoriteten av de inventerade våtmarkerna ur näringsretentionssynpunkt inte var placerade på optimala ställen. Flera hade till exempel en alldeles för liten andel åkermark i tillrinningsområdet. Andra var placerade för långt från recipienten. Även den lokala utformningenav respektive våtmark kunde i många fall varit bättre. Flera våtmarker var till exempel utformade så att vattenytans form ledde till låg hydraulisk effektivitet. Listan över negativ kritik i rapporten är visserligen lång, men den visar samtidigt att det finns stor utvecklingspotential vid anläggning av nya närsaltsfällor i Kalmar län.
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| 16. |
- Thiere, Geraldine, et al.
(författare)
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Wetland creation in agricultural landscapes : Biodiversity benefits on local and regional scales
- 2009
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Ingår i: Biological Conservation. - Barking : Elsevier. - 0006-3207 .- 1873-2917. ; 142:5, s. 964-973
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Tidskriftsartikel (refereegranskat)abstract
- Wetland creation aiming at a simultaneous increase in nutrient retention and species diversity in agricultural landscapes has recently become applied as a catchment-scale compensation measure for past wetland losses. Here, we evaluate if, and to what extend, dual-purpose wetlands benefit local and regional diversity of agricultural landscapes. We analysed composition and α, β, and γ diversity of aquatic macroinvertebrate assemblages among dual-purpose wetlands in an agricultural region in southwest Sweden in relation to local (water quality, wetland morphology, succession stage, proximity to other aquatic habitats) and landscape parameters (regional connectivity, wetland density). Diversity of mature agricultural ponds was used as a standard to evaluate the value of dual-purpose wetlands. Dual-purpose wetlands sustained α, β, and γ diversity similar to that of natural lentic water bodies in agricultural landscapes in the region and elsewhere. Over 80% of the overall species richness was attributed to β diversity, and each created wetland contributed to overall species accumulation. Ecosystem parameters explained 19% of the compositional variation among assemblages, but were only marginally related to diversity. Wetland density promoted α and γ diversity, while spatial heterogeneity (β) remained equally high, independent of wetland density. Our results indicate that catchment-scale wetland creation for simultaneous retention and diversity purposes benefits the biodiversity of agricultural landscapes, particularly if the density of aquatic habitats is increased by at least 30%.
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| 17. |
- Weisner, Stefan E.B., et al.
(författare)
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Combating eutrophication and biodiversity loss in Sweden : importance of constructed wetlands in the agricultural landscape
- 2007
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Ingår i: Multifunctions of wetland systems. - Padua : PAN. - 9788890294808 ; , s. 60-61
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 18. |
- Weisner, Stefan E.B., et al.
(författare)
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Effects of vegetation state on biodiversity and nitrogen retention in created wetlands : a test of the biodiversity–ecosystem functioning hypothesis
- 2010
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Ingår i: Freshwater Biology. - Oxford : Blackwell Publishing. - 0046-5070 .- 1365-2427. ; 55:2, s. 387-396
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Tidskriftsartikel (refereegranskat)abstract
- 1. Nitrogen retention in wetlands provides an example of an ecosystem function that is desired by human society, and is a rationale for the creation of wetlands to decrease nitrogen fluxes from nitrate-loaded river catchments to coastal waters.2. Here, we tested the impact of different vegetation states on species diversity and nitrogen retention during 4 years in surface-flow wetlands receiving nitrate-rich water. Tall emergent vegetation or submerged vegetation was introduced to six experimental wetlands each and six wetlands were left as unplanted controls for free development of vegetation. This resulted in three vegetation states dominated by emergent vegetation, by a mixture of submerged vegetation and filamentous green algae or by filamentous green algae.3. Species diversity (species richness and Shannon diversity) of plants was initially lowest in free development wetlands, but during the study became lower in the emergent vegetation wetlands than in the other wetlands. Diversity of macroinvertebrates was initially lower in the submerged vegetation wetlands than in the other wetlands, but this difference disappeared during the study. Nitrogen retention was consistently higher in emergent vegetation wetlands than in the other wetlands throughout the study.4. We conclude that plant diversity in wetlands dominated by tall emergent vegetation gradually became lower than in other wetlands, due to dominant species competitively excluding other plants. However, these wetlands were more efficient at removing nitrogen than those dominated by filamentous algae or submerged macrophytes.5. Management of wetlands often aims to decrease the dominance of tall emergent vegetation for the benefit of plant species diversity and habitat heterogeneity. Our results demonstrate a biodiversity benefit, but also show that this strategy may decrease the ability of wetlands to remove nitrogen. In this case, there is no support for the hypothesis that biodiversity enhances ecosystem function.
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| 19. |
- Weisner, Stefan E.B, et al.
(författare)
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Influence of alternative states on nitrogen removal in experimental wetlands
- 2007
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Ingår i: 2nd International Symposium on Wetland Pollutant Dynamics and Control - WETPOL 2007. - Tartu : Institute of Geography, University of Tartu. - 9789949116881 ; , s. 357-359
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Denitrification is the main process that remove nitrate from the water in wetlands. Plants can supply denitrifying bacteria with organic carbon and suitable attachment surfaces (Weisner et al. 1994). They also promote the development of anaerobic conditions through litter accumulation and decomposition, which would favour denitrification. The presence of plants has been shown to enhance nitrate removal in field studies (Bachand and Horne 2000). Toet et al. (2005) found a higher nitrogen removal in wetland compartments with emergent plants than with submersed plants. Results from microcosm studies have shown that the potential for denitrification is specific for different plant species (Bastviken et al. 2005).Wetlands may typically exist in alternative states, dominated by different kinds of vegetation. The purpose of this study was to investigate the effect of alternative state on nitrogen removal under controlled conditions in experimental wetlands.
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| 20. |
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| 21. |
- Weisner, Stefan, 1954-, et al.
(författare)
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National Large-Scale Wetland Creation in Agricultural Areas—Potential versus Realized Effects on Nutrient Transports
- 2016
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Ingår i: Water. - Basel : MDPI. - 2073-4441. ; 8:11
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Tidskriftsartikel (refereegranskat)abstract
- During 2007–2013, the Swedish Board of Agriculture granted support within a national program to about 1000 wetlands, corresponding to a 5300-hectare wetland area, with the dual goal to remove nutrients from water and to improve biodiversity in agricultural landscapes. The aim of the present study was to compare the effects on nutrient transports that are realized within the national program to what could be obtained with the same area of wetlands if location and design of wetlands were optimized. In single, highly nutrient-loaded wetlands, a removal of around 1000 kg nitrogen and 100 kg phosphorus per hectare wetland area and year was estimated from monitoring data. Statistical models were developed to estimate the overall nutrient removal effects of wetlands created within the national program. Depending on model, the effect of the national program as a whole was estimated to between 27 and 38 kg nitrogen and between 2.7 and 4.5 kg phosphorus per hectare created wetland area and year. Comparison of what is achieved in individual wetlands to what was achieved in the national program indicates that nutrient removal effects could be increased substantially in future wetland programs by emphasising location and design of wetlands.
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