| 1. |
- D'Hertefeldt, Tina, et al.
(författare)
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Extensive physiological integration in Carex arenaria and Carex disticha in relation to potassium and water availability
- 2002
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Ingår i: New Phytologist. - Chichester : Wiley. - 1469-8137 .- 0028-646X. ; 156:3, s. 469-477
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Tidskriftsartikel (refereegranskat)abstract
- Physiological integration between ramets is beneficial when acquiring heterogeneously distributed resources, and is hypothesized to occur when the benefits of resource sharing outweigh the costs. Our aim was to investigate if resource availability affected physiological integration in Carex arenaria and Carex disticha. Ramet systems were grown in high potassium and high water (K+ W+), high K and low water (K+ W-), or low K and high water (K- W+) for 1 month. Thereafter, water and K transport were traced with erythrosin and rubidium, respectively. Carex arenaria and C. disticha transported erythrosin over seven ramet generations and rubidium throughout the whole ramet system, but C. arenaria exported 20% more rubidium from the labelled shoot than C. disticha. A detailed analysis of subset of plants suggested that C. disticha in low K abundance shared more rubidium than in high K abundance, and that C. arenaria ramets in both K+ W- and K- W+ shared more resources than K+ W+ ramets. We demonstrated long-distance resource transport for K and water in C. arenaria and C. disticha. The distance of integration was not affected by resource availability in C. arenaria or C. disticha, but local concentrations of K showed marked and contrasting responses to nutrient and water treatment in both species.
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| 2. |
- Diekmann, M, et al.
(författare)
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Prediction of species response to atmospheric nitrogen deposition by means of ecological measures and life history traits
- 2002
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Ingår i: Journal of Ecology. - : Wiley. - 1365-2745 .- 0022-0477. ; 90:1, s. 108-120
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Tidskriftsartikel (refereegranskat)abstract
- 1 The main objective of this study was to predict the responses of vascular plant species to atmospheric nitrogen deposition and enhanced soil nitrogen levels. The study was carried out in deciduous forests located in three regions of southern Sweden. The abundance of vascular plants, as well as soil pH and nitrogen mineralization rates, were studied in a total of 661 sample plots. 2 We calculated an ecological measure (N-dev value) for all species based on their observed vs. expected nitrification ratios at a given soil pH, and compared its accuracy in predicting abundance changes with results using life history traits. Data from long-term field studies and fertilization experiments were used for validation. 3 N-dev values were positively correlated between neighbouring regions. Values for the southernmost region (Skane) were also positively related to the changes in species frequency observed in large-scale flora surveys and permanent plot studies in that area and with species changes reported from Central Europe. Values from one of two other regions were also consistent. N-dev values from Skane (but no other region) predicted species responses in short-term fertilization experiments. 4 No life history trait was as good a predictor as N-dev, although plant height, leaf anatomy, leaf nitrogen concentration and phenology showed significant correlations. Attributes related to taxonomy, life form, relative growth rate and habitat type showed no agreement with the changes in species abundance. 5 We predict that species with the following attribute syndrome will increase in abundance in response to enhanced nitrogen levels: those favoured by a high soil nitrification ratio relative to other species at a given soil pH, tall stature, hydro- to helomorph anatomy, high leaf nitrogen concentration and a late phenological development.
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| 3. |
- Faarinen, Mikko, et al.
(författare)
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Al-26 at the AMS facility in Lund
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 223-24, s. 130-134
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Tidskriftsartikel (refereegranskat)abstract
- To broaden the AMS programme in Lund by including Al studies, a new injector has been installed and tested at the 3 MV Pelletron accelerator. Detailed optical calculations have been performed to obtain maximum mass and energy resolution. The design of the injector, the improvement in the resolution compared to the old injector, as well as preliminary tests with a Al-26-beam, are presented. By using accelerator mass spectrometry (AMS) to measure the long-lived aluminium isotope Al-26 it has become possible to study the uptake, distribution and retention of aluminium in biological system under physiologically realistic conditions. Results from a pilot project on Al-26 in wheat plants are presented.
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| 4. |
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| 5. |
- Falkengren-Grerup, Ursula, et al.
(författare)
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Förändras floran av kvävenedfallet?
- 2000
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Ingår i: Effekter av kvävenedfall på skogsekosystem. - 9162050664
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Abstract is not available
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| 6. |
- Falkengren-Grerup, Ursula, et al.
(författare)
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Plant nitrate use in deciduous woodland: the relationship between leaf N, N-15 natural abundance of forbs and soil N mineralisation
- 2004
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Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 36:11, s. 1885-1891
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Tidskriftsartikel (refereegranskat)abstract
- Our aim was to study whether the in situ natural abundance N-15 (delta(15)N)-values and N concentration of understory plants were correlated with the form and amount of mineral N available in the soil. Also to determine whether such differences were related to earlier demonstrations of differences in biomass increase in the same species exposed to nutrient solutions with both NO3- and NH4+ or to NH4+ alone. Several studies show that the delta(15)N of NO3- in soil solution generally is isotopically lighter than the delta(15)N of NH4+ due to fractionation during nitrification. Hence, it is reasonable to assume that plant species benefiting from NO3- in ecosystems without significant NO3- leaching or denitrification have lower delta(15)N-values in their tissues than species growing equally well, or better, on NH4+. We studied the delta(15)N of six 4 understory species in oak woodlands in southern Sweden at 12 sites which varied fivefold in potential net N mineralisation rate (minNH(4)(+) + NO3-). The species decreased in benefit from NO3- in the following order: Geum urbanum, Aegopodium podagraria, Milium effusum, Convallaria majalis, Deschampsia flexuosa and Poa nemoralis. Four or five species demonstrated a negative correlation between minNO(3)(-) and leaf delta(15)N and a positive correlation between minNO(3)(-) and leaf N concentration. In wide contrast, only D. flexuosa, which grows on soils with little nitrification, showed a positive correlation between minNH(4)(+) and the leaf N concentration and delta(15)N-value. Furthermore, delta(15)N of plants from the field and previously obtained indices of hydroponic growth on NH4+ relative to NH4+ + NO3- were closely correlated at the species level. We conclude that delta(15)N may serve as a comparative index of uptake of NO3- among understory species, preferably in combination with other indices of N availability. The use of 5 15 N needs careful consideration of known restrictions of method, soils and plants.
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| 7. |
- Falkengren-Grerup, Ursula, et al.
(författare)
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Uptake capacity of amino acids by ten grasses and forbs in relation to soil acidity and nitrogen availability
- 2000
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Ingår i: Environmental and Experimental Botany. - 0098-8472. ; 44:3, s. 207-219
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Tidskriftsartikel (refereegranskat)abstract
- Uptake capacity of organic nitrogen was studied in solution experiments on eight grasses and two forbs growing in acid soils with relatively high nitrogen mineralisation in southern Sweden. Uptake of a mixture of amino acids (alanine, glutamine, glycine), that varied between 1.6 and 6.3 mu mol g(-1) dw root h(-1), could not be explained by soil data from the species' field distributions (pH, total carbon and nitrogen, potential net mineralisation of ammonium and nitrate). The ratio between organic and inorganic nitrogen (methylamine) uptake was < 0.05 for the forbs, higher for the grasses with a maximum of 1.42 for Deschampsia flexuosa. The ratio was negatively correlated with measures related to soil acidity (Ellenberg's R-value, soil nitrate and total carbon) but not, as hypothesised, with the total amount of mineralised nitrogen. The total demand on nitrogen by all components of the ecosystem would probably have described the extent to which competition among and between plants and microbes induced nitrogen limitation. In a methodological study two grasses were exposed to pH 3.8, 4.5 and 6.0 and to 50, 100 and 250 mol l(-1) of three amino acids. Uptake was also compared between intact plants and excised roots. The treatment response varied considerably between the species which stresses the importance of studying intact plants at field-relevant pH and concentrations. (C) 2000 Elsevier Science B.V. All rights reserved.
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| 8. |
- Falkengren-Grerup, Ursula, et al.
(författare)
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Use of a gradient of N-deposition to calculate effect-related soil and vegetation measures in deciduous forests
- 2003
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Ingår i: Forest Ecology and Management. - 1872-7042. ; 180:1-3, s. 113-124
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Tidskriftsartikel (refereegranskat)abstract
- Deposition of N and S has increased since the 1950s in most European countries and N accumulates in ecosystems that are not N saturated. This study shows long-term effects of a (modelled) N deposition of 7-17 kg N ha(-1) per year on biological and chemical processes in soil, vegetation composition, and functional types of field-layer plant species in deciduous forests. Soil pH largely determined the response of the soil processes, emphasising the importance to compare soils of similar acidity regarding the effects of N deposition. The most pronounced effects were demonstrated for the most acid study plots. When we compared regions with a deposition of 7 and 17 kg N ha(-1) per year we found a 40-80% higher soil N mineralisation rate, 2-90% higher nitrification rate and 10-25% lower C:N ratio in the region with the highest deposition. Similar but smaller differences were indicated when regions with a deposition of 7 and 10 kg N ha(-1) per year were compared. Number of species was lower in the regions with the highest deposition. Literature data for plants on N concentration, nitrate reductase activity (NRA), growth rates, morphology and height were calculated on a site basis. They varied to different extent between the regions. The N concentration was 7-24% higher in the regions with the highest N deposition. We argue that the effect-related critical load based on our results should be set to a N deposition of 7-10 kg N ha(-1) per year. Critical loads for a subdivision of deciduous forests would give lower critical loads for the most acid soils compared to less acid soil.
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| 9. |
- Falkengren-Grerup, Ursula, et al.
(författare)
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Vascular plants as indicators of nitrogen enrichment in soils
- 2004
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Ingår i: Plant Ecology. - 1573-5052. ; 172:1, s. 51-62
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Tidskriftsartikel (refereegranskat)abstract
- The quantification of species along environmental gradients has long been the subject of study regarding natural plant communities and, more recently, ecosystems disturbed by anthropogenic emissions of eutrophying and acidifying substances. We studied 527 sites in southern Swedish deciduous forests divided into two regions, with mean nitrogen depositions of 17 and 9 kg ha(-1) y(-1). The higher deposition in the more exposed region has resulted in higher nitrogen mineralisation and nitrification rates. The objective was to identify nitrogen indicators, which we defined as species with a skewed distribution in relation to the net potential nitrogen mineralisation in the soil. Soil pH was introduced as a co-variable as it may relate to other factors limiting plant growth and survival in these ecosystems. We tested the distribution of the net potential mineralised ammonium (minNH(4)(+)), nitrate (minNO(3)(-)), total inorganic nitrogen (minNH(4)(+)+NO3-) and the ratio of nitrification (percentage of minNH(4)(+)+NO3- as nitrate; %minNO(3)(-)) in 77 herbs. The number of species that showed a skewed distribution differed for the nitrogen variables studied in the following order: %minNO(3)(-) > minNO(3)(-) > minNH(4)(+) much greater than minNH(4)(+)+NO3-. As many as 21 species in region 1 and 17 species in region 2 were selected as indicators for one or several of the nitrogen variables. A fern, five graminoids and seven forbs were found to be indicators of low %minNO(3)(-) and two ferns, two grasses and 13 forbs were found to be indicators of high %minNO(3)(-). We correlated the Ellenberg N indicator values with species with and without skewed distributions, and found that the former group was best related to the N values. As with most indicators, the species identified here are probably best used in combination with other measures to demonstrate the effects of nitrogen deposition on vegetation.
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| 10. |
- Lokke, H, et al.
(författare)
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Critical Loads
- 2000
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Ingår i: Arbejdsrapport fra DMU No. 121. ; , s. 1-48
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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