| 1. |
- Edelfeldt, Stina, et al.
(författare)
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Age-Independent Adult Mortality in a Long-Lived Herb
- 2019
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Ingår i: Diversity. - : MDPI AG. - 1424-2818. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- Relative to mammals and birds, little is known about the mortality trajectories of perennial plants, as there are few long-term demographic studies following multiple yearly cohorts from birth to death. This is particularly important because if reproductively mature individuals show actuarial senescence, current estimations of life spans assuming constant survival would be incorrect. There is also a lack of studies documenting how life history trade-offs and disturbance influence the mortality trajectories of plants. We conducted Bayesian survival trajectory analyses (BaSTA) of a 33-year individual-based dataset of Pulsatilla vulgaris ssp. gotlandica. Mortality trajectories corresponded to Type III survivorship patterns, with rapidly decreasing annual mortality rates for young plants, but with constant mortality for reproductively mature individuals. We found trade-off effects resulting in a cost of growth for non-reproductive plants but no apparent cost of reproduction. Contrarily to our expectation, young plants that had previously shrunk in size had a lower mortality. However, accounting for trade-offs and disturbance only had minor effects on the mortality trajectories. We conclude that BaSTA is a useful tool for assessing mortality patterns in plants if only partial age information is available. Furthermore, if constant mortality is a general pattern in polycarpic plants, long-term studies may not be necessary to assess their age-dependent demography.
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| 2. |
- Edelfeldt, Stina, et al.
(författare)
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Demographic senescence and effects on population dynamics of a perennial plant
- 2019
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Ingår i: Ecology. - : WILEY. - 0012-9658 .- 1939-9170. ; 100:8
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Tidskriftsartikel (refereegranskat)abstract
- Demographic rates in plants are usually assumed to be more stage or size dependent than age dependent, and aging is therefore not considered in demographic models. However, little is known about the effect of age on demographic rates, as there still are few studies based on long-term individual-based plant population data that consider both individual age and size. In addition, little is known about how aging of individuals may affect population dynamics. We present analyses of demographic data for three populations of Fumana procumbens collected 1985-2013, on individuals with known year of germination. We modeled age- and size-dependence of the vital rates of survival, growth, fruiting probability, and fruit number using thin plate spline regressions, and constructed an age x size integral projection model (IPM) to project population-level effects of aging. We found strong correlations between age and vital rates in solely age-based vital rate models, where vital rates initially increased with age, after which they stabilized and, in some cases, eventually declined. In survival models with both age and size, the effects of age were statistically significant, whereas size effects were insignificant at two of the sites. For other vital rates, most of the effect of age could be explained by size alone. In addition, including the age effects on survival in the IPM led to lower population growth rates compared to predictions of a size-only IPM. These results illustrate that demographic senescence does occur in perennial plants, which has only been demonstrated clearly in a few recent detailed studies. Moreover, we show that population projections may be overly optimistic if they do not consider plant age. We conclude that the possibility of demographic senescence should be considered in demographic population models, such as those used in viability analyses of threatened species.
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| 3. |
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| 4. |
- Edelfeldt, Stina, et al.
(författare)
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Effects of Cutting Length, Orientation and Planting Depth on Early Willow Shoot Establishment
- 2015
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Ingår i: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 8, s. 796-806
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Tidskriftsartikel (refereegranskat)abstract
- To assess the effects of different planting systems on early performance (survival, shoot emergence time, number of shoots, maximum shoot height and biomass shoot production) of willow, cuttings of varying lengths were planted horizontally at different depths and compared with vertically planted cuttings. Cutting lengths of (i) 25-200 cm and (ii) 7-21 cm were studied in a field experiment and in a box experiment, respectively. Shorter cuttings planted deeper had a lower survival rate and emerged a few days later compared to longer cuttings planted shallower. The performance was considerably higher at the apical part of the cuttings, regardless of cutting length. Longer cuttings planted shallow had a higher performance. Vertically planted cuttings produced more biomass and shoots per length unit than horizontally planted cuttings. We conclude that planting systems based on the use of longer horizontally planted cuttings would probably lead to an uneven establishment and gaps in the stand caused by apical dominance. Also, to achieve the same performance, the need of planting material would be considerably higher compared to systems with vertically planted cuttings. To obtain a fast and more even early establishment of willows, we recommend the use of vertically planted cuttings with a length of at least 20 cm. If cuttings are planted horizontally, they should not be planted deeper than 5 cm.
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| 5. |
- Edelfeldt, Stina, et al.
(författare)
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Effects of cutting traits and competition on performance and size hierarchy development over two cutting cycles in willow
- 2018
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 108, s. 66-73
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Tidskriftsartikel (refereegranskat)abstract
- To assess if cutting traits (clone, fresh weight) in combination with strong competition from adjacent willows (planted in monoclonal stands and clonal mixtures) affected performance and size hierarchy development in willow during consecutive harvests, a field experiment was performed in central Sweden during 2008-2015. Cuttings from five Salix clones were planted in 1.8 m x 1.8 m plots, at a density of 197 500 cuttings ha(-1) in monoculture and in ten mixtures using two clones (i.e. 15 combinations). Maximum height was measured each year and the experiment was harvested after the growing seasons 2012 and 2014. Larger cuttings produced stools with lower death rate, higher maximum height and larger biomass production compared to smaller cuttings. The high competition pressure resulted in 9.2% stool death at harvest 2012 and 39% stool death at harvest 2014. Tora (Salix schwerinii x Salix viminalis) showed the highest performance and Jorr (Salix viminalis) and Gudrun (Salix dasyclados) the lowest. Planting system had less effect on stool death, height development and biomass production. Tora was the only clone producing more biomass when grown in mixtures compared to monoculture. The size hierarchy between individual stools was generally kept during the experimental period in both monocultures and mixtures, even if the height correlations decreased with year. To obtain a more even establishment of willow stands and lower the risk of a size hierarchy developing leading to large stool mortality and gaps in the stand, we recommend the use of larger and more even-sized cuttings.
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| 6. |
- Edelfeldt, Stina, et al.
(författare)
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Effects of mechanical planting on establishment and early growth of willow
- 2013
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 55, s. 234-242
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Tidskriftsartikel (refereegranskat)abstract
- Commercial willow planting is mostly performed by machines, using long rods which are automatically pressed in the soil and cut. This procedure exerts a large mechanical impact on the cuttings, and may lead to damage, especially when planted in compacted soils. We studied cuttings and early growth performance of willow (in terms of produced shoot biomass, shoot height, leaf area, and number of shoots per cutting) after machine planting, in comparison to manually prepared and planted cuttings. To isolate the effect of mechanical planting from the effects of field variation after planting, we dug out cuttings from five different clones directly after machine planting in well prepared and compacted soil respectively and grew them under controlled conditions, together with a manually prepared control. We found that undamaged cuttings had a better growth performance than visibly damaged cuttings. Planting by machine on compacted soil resulted in a relatively large number of cuttings landing on the soil surface, instead of being planted vertically in the soil. Soil compaction and machine planting interacted with cutting dimensions, the poorer performance of thinner cuttings being more pronounced in compacted soil. To obtain a faster and more even establishment of willows, we recommend thorough soil cultivation prior to planting, further development of planting machines to minimize damage to cuttings at planting, and the use of cuttings with a diameter of at least 10-11 mm. (C) 2013 Elsevier Ltd. All rights reserved.
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| 7. |
- Edelfeldt, Stina, et al.
(författare)
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Establishment and Early Growth of Willow at Different Levels of Weed Competition and Nitrogen Fertilization
- 2016
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Ingår i: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 9, s. 763–772-
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate the effects of weed competition and nitrogen fertilization on the early growth performance of willow, cuttings of the clone Tora (Salix schwerinii x S. viminalis) were planted in buckets together with model weeds (spring barley or white mustard) sown 15, 26, and 30 days after willow planting. The buckets were fertilized with 30 or 90 kg N ha(-1). Willow with weeds sown after 15 days produced less biomass and smaller leaf area and had a lower maximum shoot height compared to willow planted without weeds and willow with weeds sown after 26 or 30 days. Fertilization with 90 kg N ha(-1) gave higher willow biomass production in willow with weeds sown after 26 or 30 days. Type of model weed had no effect on willow performance. Weed biomass and maximum shoot height were higher in weeds planted without willows compared to the willow-weed mixtures. A high nitrogen level gave more weed biomass when planted without willows and in the willow-weed mixture with weeds sown after 15 days. We conclude that for the given high density of willow, competition from weeds emerging soon after willow planting had strong effect on early production. Furthermore, if there is a risk of weed infestation, fertilization should be delayed.
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| 8. |
- Edelfeldt, Stina, et al.
(författare)
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Evaluation and Comparison of Ecological Models Simulating Nitrogen Processes in Treatment Wetlands, Modeled in Modelica
- 2005
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Konferensbidrag (refereegranskat)abstract
- The global problem of eutrophication, the enrichment of water bodies by nutrients, has inrecent years resulted in an increased interest in non-conventional ways to reduce the amount of nutrients discharged into the environment. One of the more commonly proposed and also used solutions is to append artificial or constructed wetlands as a final step in the treatment of wastewater. However, both the construction of the wetlands and the maintenance thereof are time and resource consuming, hence a high production and maintenance cost. Due to these high costs, tools for modeling and simulation have turned out to be valuable asset in the development of constructed wetlands.In this paper, two ecological models of nitrogen processes in treatment wetlands have beenmodeled, simulated, and visualized using the Modelica language. The results show that nitrogen decrease in a constructed treatment wetland can well be simulated using the Total Nitrogen or the Nitrification/Denitrification model expressed in Modelica and the MathModelica Model Editor.
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| 9. |
- Edelfeldt, Stina, et al.
(författare)
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Evaluation and Comparison of Models and Modeling Tools Simulating Nitrogen Processes in Treatment Wetlands
- 2005
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Ingår i: Proceedings of the 46th Conference on Simulation and Modelling of the Scandinavian Simulation Society (SIMS2005), Trondheim, Norway, October 13-14, 2005.. - : Tapir Academic Press. - 8251920930 - 9788251920933
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Konferensbidrag (refereegranskat)abstract
- The global problem of eutrophication, the enrich-ment of water bodies by nutrients, has in recent years resulted in an increased interest in non-conventional ways to reduce the amount of nutri-ents discharged into the environment. One com-monly proposed and used solution is to append constructed wetlands as a final step in the treat-ment of wastewater. However, both the construc-tion of the wetlands and the maintenance thereof are time and resource consuming. Due to the high production and maintenance costs, tools for mod-eling and simulation are often valuable assets in the development of constructed wetlands. In this paper, two ecological models of nitrogen processes in treatment wetlands have been evalu-ated and compared. These models were imple-mented, simulated, and visualized in the Modelica language . The differences and similarities be-tween the MathModelica Model Editor and three ecological modeling tools have also been evalu-ated.
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| 10. |
- Edelfeldt, Stina
(författare)
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Influence of Pre-emergence Cutting Characteristics on Early Willow Establishment
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In willow cultivation, successful establishment is crucial for the development of a willow crop. The overall objective of this study was to assess the effects of pre-emergence cutting characteristics on the performance of willow during early establishment. In the experiments described in this thesis, cuttings of different size, position on the original rod, quality (i.e. planting damages and storage effects), orientation (i.e. vertical or horizontal planting), and clone were planted in the field or in boxes in an outdoor enclosure. Effects of weed competition and nitrogen fertilization were tested in a bucket experiment, and long-term effects of cutting characteristics on development and growth were evaluated in a field experiment harvested twice between 2008 and 2015. Cutting characteristics had a significant influence on the early establishment of willow. Cutting size had the most apparent influence, with performance generally increasing with increased size. There was a tendency for this effect to level off beyond a certain size. Cuttings sprouted earlier if derived from the apex, and the majority of the shoots on horizontally planted cuttings originated from the apical part. Cutting damage caused by storage or machine planting on compacted soil resulted in decreased performance and increased variation. Cuttings planted on compacted soil had higher probability of being damaged or landing on the soil surface instead of in the soil. Vertically planted cuttings were generally preferable to horizontally planted cuttings, especially when considering the amount of planting material needed. If planted horizontally, the depth should not exceed 5 cm. Weed competition resulted in a considerable decrease in performance if weeds sprouted before the willow had reached sufficient size. Nitrogen fertilization was likely to be of more use to the weeds than to the willow. In the long-term experiment, stool weight increased with cutting weight and early plant size at both harvests, indicating that the initial size hierarchy was maintained during the entire experiment. The performance responses in the experiments varied depending on clone.
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