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- Hellsten, Sofie, et al.
(författare)
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Halter av baskatjoner, fosfor och kväve i stubbar i Sverige, Finland och Danmark
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Intresset för stubbskörd har ökat kraftigt på senare år, i takt med att efterfrågan på förnyelsebar energi ökat. Idag saknas det information om näringshalter i stubbar för att utröna effekten av stubbuttag på näringsbalans och försurning. Denna studie syftar till att ta fram ett större dataunderlag för halter i stubbar i Sverige, Finland och Danmark. Lokalerna representerar olika nedfallsnivåer, olika markförhållanden samt olika beståndsdata. Studien omfattar granstubbar från Sverige, Finland och Danmark, samt tall- och björkstubbar från Sverige. Följande näringsämnen ingick i studien: kväve (N), fosfor (P), kalcium (Ca), kalium (K), magnesium (Mg) och Natrium (Na). Resultaten indikerade att näringshalten i björkstubbar är högre jämfört med gran och tall. I Sverige och Finland noterades generellt sett högre näringshalter i stubbarna i södra delen av landet jämfört med norra delen, med undantag av fosfor. Näringshalterna är betydligt högre i stubbens och rötternas bark jämfört med veden. Halterna i rötterna ökade signifikant med minskad rotdiameter. För tallstubbarna i Jädraås noterades signifikant minskande näringshalter i stubbarna med åldern upp till 65 år för kväve, kalium, magnesium och fosfor. För Jädraås, som har den största representationen av ståndortsindex, noterades ökande halter med ståndortsindex för fosfor och kalium. Studien har medfört att dataunderlaget för halter i stubbar har ökat väsentligt vilket kan bidra till att minska osäkerheterna i beräkningar av näringsbalansen i skogsmark vid stubbskörd.
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| 3. |
- Hellsten, Sofie, et al.
(författare)
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Nutrient concentrations in stumps and coarse roots of Norway spruce, Scots pine and silver birch in Sweden, Finland and Denmark
- 2013
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 1872-7042 .- 0378-1127. ; 290, s. 40-48
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to evaluate the concentrations of nutrients in stumps and coarse roots in Norway spruce, Scots pine and silver birch in Sweden, Finland and Denmark, and to assess how nutrient concentrations vary with site characteristics, stand age and root size. Concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na) in spruce, pine and birch stumps were assessed in eight sites across Scandinavia. Nutrient concentrations were higher in birch than in spruce and pine. In Sweden and Finland, the nutrient concentrations were generally higher at the southern sites than at the sites located in the northern part of the countries, except for P. For all nutrients, concentrations were significantly higher in the bark of the stump and roots than in the wood. Furthermore, nutrient concentrations increased significantly with decreasing root diameter. This study did not demonstrate any correlations with stand age. Further studies are needed to provide a broader picture of how the stump nutrient contents vary with site characteristics and forest management practices to provide a better foundation for nutrient balance calculations when setting up recommendations for stump removal. (C) 2012 Elsevier B.V. All rights reserved.
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- Valiranta, Minna, et al.
(författare)
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Scattered late-glacial and early Holocene tree populations as dispersal nuclei for forest development in north-eastern European Russia
- 2011
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 38:5, s. 922-932
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Tidskriftsartikel (refereegranskat)abstract
- Aim Concepts about patterns and rates of post-glacial tree population migration are changing as a result of the increasing amount of palaeobotanical information being provided by macroscopic plant remains. Here we combine macrofossil, pollen and stomata records from five sites in north-eastern European Russia and summarize the results for the late-glacial-early Holocene transition. The late-glacial-early Holocene transition encompasses the first indications of trees (tree-type Betula, Picea abies, Abies sibirica and Larix sibirica) and subsequent forest development. Considerable time-lags between the first macrobotanical and/or stomata finds of spruce (Picea abies) and the establishment of a closed forest are reconsidered. Location Pechora basin, north-eastern European Russia. Methods We used plant macrofossil, stomata, pollen and radiocarbon analyses to reconstruct late-glacial and early Holocene tree establishment and forest development. The data were derived from lake sediment and peat archives. Results Palaeobotanical data reveal an early Holocene presence (11,500-10,000 cal. yr bp) of arboreal taxa at all five sites. One site presently located in the northernmost taiga zone, shows the presence of spruce and reproducing tree birch during the late-glacial. Given the current view of post-glacial population dynamics and migration rates, it seems likely that the source area of these early tree populations in north-eastern European Russia was not located in southern Europe but that these populations had local origins. Results thus support the emerging view that the first post-glacial population expansions in non-glaciated regions at high latitudes do not reflect migration from the south but were a result of an increase in the size and density of small persisting outlying tree populations. Main conclusions Results suggest that the area east of the margin of the Scandinavian ice sheet to the Ural Mountains had isolated patches of trees during the late-glacial and early Holocene and that these small populations acted as initial nuclei for population expansion and forest development in the early Holocene.
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