Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2008
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Vegetation fire is the worldwide disturbance that affects the largest area and biggest biomes variety. Fire instantaneously generates large C fluxes to the atmosphere, as gas and soot particles. In the same time, part of ecosystem organic matter (OM) is converted into charred material that may contribute to the stable pool of soil organic carbon (SOC). The net effect of vegetation fire on C sequestration remains uncertain because the two major impacts operate at very different timescales and C budget is highly dependent on ecosystem and fire conditions. The aim of the present research was to assess fire-induced C fluxes to the atmosphere and as new litter and charcoal production during a prescribed fire in a subtropical oak shrub. Pre-fire biomass and post-fire charred and unburned biomass were determined for vegetation leaves and stems, litter and soil in 20 sub-plots installed in a 30-ha area prescribed for fire. Concentrations of C were determined, and fluxes among pools and to the atmosphere were derived from these measurements. In a first assessment, charred OM was visually identified in standing biomass and litter using its black and shiny aspect. In a second step, a strong chemical oxidation with K2Cr2O7/H2SO4 was used to isolate only a highly recalcitrant part of pyrogenic C. After the fire, standing dead biomass was only composed of stems with charred surface. The leaves transferred from vegetation to litter during the fire represented more than a half of post-fire litter. Percentage of initial C pool that was lost to the atmosphere as gas or particles was 55 % from vegetation stems, 80 % from vegetation leaves, and 70 % from litter. Soil C stocks were not significantly modified by fire, in agreement with moderate temperature elevation in the soil proper. Total C release to the atmosphere, including gas and particles, was 2.6 kg C m"2. Visually-identified charcoal represented 5% of remaining stem C (i.e. 60 g C m"2) and 21% of post-fire litter C (i.e. 80 g C m"2). The stem and litter charcoal contained 4±4 % and 16±5 % of highly recalcitrant C, respectively. We assessed that a typical scrubland fire may add between 10 and 140 g C m"2of chemically stable pyrogenic C to the soil. The conversion rate of ecosystem C to chemically stable pyrogenic C would be between 0.2 and 3.4 %.
Sammendrag
Carbon from complex and structural plant molecules has long been considered more efficiently retained in soils than that of soluble molecules. This dominant paradigm is now being challenged by data emerging from recent isotopic-labeling and compoundspecific isotopic studies. We recently demonstrated that large proportions of plantresidue lignin decompose within a year of incorporation to soils, and that soilextracted lignin has a turnover time of about 20 years (Rasse et al, 2006). In contrast, turnover time of soil-extracted polysaccharides can reach 40 years (Gleixner et al., 2002). Long-term incubation studies have shown that C from labeled glucose is better conserved in certain soil types than C from more complex molecules such as cellulose (e.g. Vinten et al, 2002). These studies suggest that the initial decomposability of plant molecules has limited impact on the long-term fate of their constitutive C in soils. Here we will present a new model where soluble molecules have a competitive advantage over structural molecules for the long-term preservation of their constitutive C in soils. Implementation of compound-specific data in quantitative soil models will also be discussed.
Sammendrag
Carbon dioxide and methane -besides water vapor the most powerful greenhouse gases - have been increasing rapidly in recent decades. A huge reservoir of both gases is stored in boreal soils including permafrost, and a major change in the carbon balance of this reservoir might have dramatic impacts on future climate change. So far, Norway has lacked any infrastructure to assess fluxes of both gases from unique boreal ecosystems, e.g., sub-arctic peatlands exposed to oceanic climate. In spring 2008, Bioforsk, SERC and NILU started an initiative to fill this gap by establishing a flux tower station in the Dverberg peatlands on the island of Andøya in Northern Norway. The site is especially suited for such studies, because it extends an existing flux measurement infrastructure in Abisko, N-Sweden and Sodankylä, N-Finland to include an ecosystem with comparatively mild climate, compared to the Alpine Arctic climate of Abisko and the continental- subarctic climate of Sodankylä.
Forfattere
Eva SkarbøvikSammendrag
Det er ikke registrert sammendrag
Sammendrag
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Sammendrag
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Sammendrag
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Forfattere
Eva SkarbøvikSammendrag
Det er ikke registrert sammendrag
Forfattere
Eva SkarbøvikSammendrag
Det er ikke registrert sammendrag