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- Aguetoni Cambui, Camila, et al.
(författare)
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Patterns of Plant Biomass Partitioning Depend on Nitrogen Source
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) availability is a strong determinant of plant biomass partitioning, but the role of different N sources in this process is unknown. Plants inhabiting low productivity ecosystems typically partition a large share of total biomass to belowground structures. In these systems, organic N may often dominate plant available N. With increasing productivity, plant biomass partitioning shifts to aboveground structures, along with a shift in available N to inorganic forms of N. We tested the hypothesis that the form of N taken up by plants is an important determinant of plant biomass partitioning by cultivating Arabidopsis thaliana on different N source mixtures. Plants grown on different N mixtures were similar in size, but those supplied with organic N displayed a significantly greater root fraction. (15)N labelling suggested that, in this case, a larger share of absorbed organic N was retained in roots and split-root experiments suggested this may depend on a direct incorporation of absorbed amino acid N into roots. These results suggest the form of N acquired affects plant biomass partitioning and adds new information on the interaction between N and biomass partitioning in plants.
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- Gruffman, Linda, et al.
(författare)
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Cultivation of Norway spruce and Scots pine on organic nitrogen improves seedling morphology and field performance
- 2012
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 276, s. 118-124
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen availability exerts a significant control on biomass allocation of plants including Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris (L)) in boreal forest ecosystems. Recent studies suggest, however, this control differs for inorganic and organic nitrogen sources. The importance of the chemical form of nitrogen (inorganic or organic) for the morphology and growth of conifer seedlings was studied during production of seedlings in a forest nursery and subsequently in a field trial in northern Sweden. Seedlings were supplied with two different nutrient solutions; an inorganic conventional fertilizer and an organic, amino acid-based fertilizer. Seedlings cultivated on the organic nitrogen source displayed larger root systems resulting in a higher root: shoot ratio than did seedlings cultivated on the inorganic nitrogen source. The proportion of fine roots to lateral roots and the root tip proportion colonized by mycorrhiza were positively affected by the organic nitrogen source. Norway spruce seedlings cultivated on organic nitrogen displayed significantly increased shoot growth compared to seedlings cultivated on inorganic nitrogen. Our results suggest that the chemical form of nitrogen influences the allocation of biomass in conifer seedlings. The shift in allocation of resources to root biomass further leads to a competitive advantage in field conditions, resulting in a significant increase in shoot growth one year following transplant. (C) 2012 Elsevier B.V. All rights reserved.
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| 5. |
- Hedwall, Per-Ola, et al.
(författare)
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Interplay between N-form and N-dose influences ecosystem effects of N addition to boreal forest
- 2018
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 423, s. 385-395
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen (N) addition effects on boreal forest ecosystem are influenced by an interplay between N-form and N-dose. We hypothesize that trees take up organic N more efficiently than inorganic N and that unwanted side-effects of organic N are smaller. We predicted that 1) the tree growth response to arginine (ARG) addition is larger than to ammonium-nitrate (AN) and, 2) understory vegetation and ectomycorrhizal (EcM) changes following ARG addition are smaller than following AN addition.We investigated the effects of AN and ARG addition (50 and 150 kg N ha(-1)) during five years on tree growth, understory vegetation and EcM fungi in a Pinus sylvestris L. forest (c 50 years old) in northern Sweden.N addition increased tree growth and changed understory vegetation composition with few significant differences between AN and ARG. Differences in responses mainly occurred for the bryophyte Pleurozium schreberi which decreased more from ARG, and for EcM sporocarps, which sharply declined from AN, but not from ARG.We found very few differences in responses between AN and ARG addition with the exception of EcM and bryophytes. These species groups have several key functions in boreal forests and the differences in responses merits further investigations.
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| 6. |
- Helmers, Rolf, et al.
(författare)
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Mälsåkers Slott
- 1991
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Rapport (populärvet., debatt m.m.)abstract
- Läsåret 1990-91 har vi valt ett större restaureringsprojekt, Mälsåkers slott vid Mälaren. Tessinslottet från 1680-talet skadades svårt vid en brand 1945. Den avbrända takkonstruktionen rekonstruerades, de rötskadade bjälklagen byttes mot nya i betong och de gamla originalfönstren ersattes. Vårt syfte med Mälsåkersstuierna har varit att träna ett arbetssätt och utveckla en metodik för undersökningoch analys. Först därefter konkretiseras diskussionen om byggnadens användning med utgångspunkt från dess egna förutsättningar. Studier av allt från grund till takstolar, från yttre miljö tillinteriörer och snickeridetaljer har kopplats till arkivstudier och till undervisningen i övrigt. Målet har varit att visa hur byggnaden är konstruerad och på vilket sätt den utnyttjats under århundraden med förändringar av inredningar, rumssammanhang och konstruktiva system.
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| 7. |
- Helmers, Rolf, et al.
(författare)
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Villa Johansson : återskapandet av en miljö
- 1995
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Ingår i: Kulturmiljövård. - Stockholm : Riksantikvarieämbetet. - 1100-4800. ; :1-2, s. 130-132
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 8. |
- Lim, Hyungwoo, et al.
(författare)
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Annual climate variation modifies nitrogen induced carbon accumulation of Pinus sylvestris forests
- 2017
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 27, s. 1838-1851
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Tidskriftsartikel (refereegranskat)abstract
- We report results from long-term simulated external nitrogen (N) input experiments in three northern Pinus sylvestris forests, two of moderately high and one of moderately low productivity, assessing effects on annual net primary production (NPP) of woody mass and its interannual variation in response to variability in weather conditions. A sigmoidal response of wood NPP to external N inputs was observed in the both higher and lower productivity stands, reaching a maximum of similar to 65% enhancement regardless of the native site productivity, saturating at an external N input of 4-5 g N . m(-2) . yr(-1). The rate of increase in wood NPP and the N response efficiency (REN, increase in wood NPP per external N input) were maximized at an external N input of similar to 3 gN . m(-2) (.) yr(-1), regardless of site productivity. The maximum REN was greater in the higher productivity than the lower productivity stand (similar to 20 vs. similar to 14 g C/g N). The N-induced enhancement of wood NPP and its REN were, however, markedly contingent on climatic variables. In both of the higher and lower productivity stands, wood NPP increased with growing season precipitation (P), but only up to similar to 400 mm. The sensitivity of the response to P increased with increasing external N inputs. Increasing growing season temperature (T) somewhat increased the N-induced drought effect, whereas decreasing T reduced the drought effect. These responses of wood NPP infused a large temporal variation to REN, making the use of a fixed value unadvisable. Based on these results, we suggest that regional climate conditions and future climate scenarios should be considered when modeling carbon sequestration in response to N deposition in boreal P. sylvestris, and possibly other forests.
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| 9. |
- Lutter, Reimo, et al.
(författare)
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Belowground resource utilization in monocultures and mixtures of Scots pine and Norway spruce
- 2021
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 500
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Tidskriftsartikel (refereegranskat)abstract
- Mixed forests have been recommended to replace monocultures, often being more productive and resilient ecosystems. Those benefits of species mixing have been suggested to be attributed to lower competition (aboveand belowground) due to potential separation of resource acquisition strategies, yet a mechanistic understanding of belowground processes has largely been missing. We applied an isotopic-labelling technique using N-15 and H-2 at similar to 5 cm soil depth to study acquisition of two important resources, nitrogen (N) and water, in a replicated field experiment including mature Scots pine and Norway spruce monocultures and their mixture in boreal Sweden. Based on the isotopic data, we modelled distance-dependent N and water uptake and described the horizontal reach of active rooting areas around trees. The active root area for both N and water uptake in monocultures of both species was approximately 6-10 m(2). Substantially wider areas were observed inside the mixture for N acquisition (27 m(2) for pine and 21 m(2) for spruce). Water was mainly acquired from within a 12-15 m(2) area in mixture. The mixture and the pine monocultures exhibited similar recovery of the added N-15 (3.8-4.5%) and its uptake per unit of foliage mass. The recovery of N-15 for the spruce monocultures was generally lower (2.1%) but no difference was noted in the uptake per unit of foliage mass between spruce monoculture and mixture. No differences were found for recovery of H-2 between the stand types. Mixing pine and spruce did not improve the resource uptake in comparison with the estimated theoretical mixture (according to the normalized basal area in monocultures). However, the mixing revealed significant differences between tree species whereas pines inside the mixture recovered 11.3-fold more N-15 than accompanying spruce. Root overlap of 3-11 trees on 1 m(2) was observed in all stand types, far exceeding the degree of canopy overlap. We discuss this overlap in terms of competition between individual trees. Spruces have proportionally larger horizontal rooting area relative to their aboveground size than pines. Scots pine and Norway spruce mixing in this type of boreal forest does not significantly enhance resource acquisition but leads to compensatory partitioning of growth, suggesting fierce interspecific competition, rather than niche separation.
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| 10. |
- Malmgren, Helge, 1945, et al.
(författare)
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Ivar Segelberg – philosopher and botanist
- 2014
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Ingår i: Philosophy and Botany. Essays on Ivar Segelberg. Eds. H. Malmgren, T. Nordin & C. Svennerlind. - Stockholm : Thales. - 9789172350953 ; , s. 13-32
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- A biography of Ivar Segelberg (1914–1987).
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