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.
2007
Sammendrag
available, especially in Norway. The objective of the present research was to estimate C losses from cultivated peatlands in West Norway by three independent methods: 1) long-term monitoring of subsidence rates, 2) changes in ash contents, and 3) soil CO2 flux measurements. Subsidence of cultivated peat soils averaged about 2.5 cm y-1. We estimated that peat loss and compaction were respectively responsible for 38% and 62% of the total subsidence during a 25-year period after drainage. Based on this estimate the corresponding C loss equals 0.80 kg C m-2 yr-1. The observed increase in mineral concentration of the topsoil of cultivated peat is proportional to their C loss, providing no mineral particles other than lime and fertilizers are added to the soil. Using this novel approach across 11 sites, we estimated a mean C loss of 0.86 kg C m-2 y-1. Soil CO2 flux measurements, corrected for autotrophic respiration, yielded a C loss estimate from cultivated peat soils of 0.60 kg C m-2 yr-1. The three methods yielded fairly similar estimates of C losses from Norwegian cultivated peatlands. Cultivated peatlands in Norway cover an estimated 63 000 ha. Total annual C losses from peat degradation were estimated to range between 1.8 and 2 million tons CO2 y-1, which equals about 3-4 % of total anthropogenic greenhouse gas emissions from Norway.
Forfattere
Marie-France Dignac Cornelia Rumpel Daniel Rasse Mercedes Mendez-Millan Haithem Bahri André MariottiSammendrag
Little is known on the relationship between the chemical composition and the dynamics of plant biomolecules in soils at the long-term scale. Chemical recalcitrance of specific molecules such as lignins has been proposed as a possible factor governing organic matter stabilization in soils. Other stabilization mechanisms, involving soil mineral constituents, may act differently on above- and belowground tissues of plants, leading to contrasting contributions of these tissues to soil organic matter (SOM). Cutins and suberins are present respectively in the aboveground and the belowground tissues of higher plants and can be used as biomarkers of the inputs of these plant tissues to soils. Using compound specific isotopic tracer techniques applied to agricultural lands converted from C3 plant to C4 plant cropping, we followed the molecular turnover of lignins, cutins and suberins in soils, in order to assess their specific residence times, and infer the contributions of above- and belowground tissues to SOM. We showed that lignin turnover in soil is faster than that of total organic carbon. We evidenced contrasting behaviour of lignin as well as cutin/suberin monomers on a molecular basis which may be related to their chemical nature, their position into the polymeric structure and to the plant tissue in which they are present. Therefore, we suggest that compound specific isotope measurements in combination with longterm field trials could lead is understanding of soil carbon stocks and fluxes on a molecular level.
Sammendrag
NA
Forfattere
Marie Alexis Daniel Rasse C. Rumpel G. Bardoux N. Péchot P. Schmalzer B.G. Drake A. MariottiSammendrag
Fire profoundly modifies the terrestrial C cycle of about 40% of the Earth"s land surface. The immediate effect of fire is that of a net loss of C as CO2 gas and soot particles to the atmosphere. Nevertheless, a proportion of the ecosystem biomass is converted into charcoal, which contains highly recalcitrant molecular structures that contribute to long-term C storage. The present study aimed to assess simultaneously losses to the atmosphere and charcoal production rates of C and N compounds as a result of prescription fire in a Florida scrub-oak ecosystem. Pre-fire and post-fire charred and unburned organic matter stocks were determined for vegetation leaves and stems, litter and soil in 20 sub-plots installed in a 30-ha area that was subjected to prescribed fire. Concentrations of C and N were determined, and fluxes among pools and to the atmosphere were derived from these measurements. Soil C and N stocks were unchanged by the fire. Post-fire standing dead biomass contained 30% and 12% of pre-fire vegetation C and N stocks, respectively. In litter, post-fire stocks contained 64% and 83% of pre-fire C and N stocks, respectively. Most of the difference in relative losses between vegetation and litter could be attributed to substantial litter fall of charred and unburned leaves during the fire event. Indeed, an estimated 21% of pre-fire vegetation leaf C was found in the post-fire litter, while the remaining 79% was lost to the atmosphere. About 3/4 of the fire-induced leaf litter fall was in the form of unburned tissue and the remainder was charcoal, which amounted to 5% of pre-fire leaf C stocks. Charcoal production ranged between 4% and 6% of the fireaffected biomass, i.e. the sum of charcoal production and atmospheric losses. This value is below the range of literature values for the transformation of plant tissue into stable soil organic matter through humification processes, which suggests that fire generates a smaller quantity of stable organic C than humification processes over decades and potentially centuries.
Forfattere
Kjell Andreassen Volkmar Timmermann Nicholas Clarke Ingvald Røsberg Halvor Solheim Wenche AasSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
In the context of an ongoing project on REMote sensing of FORest health (REM-FOR), we analyze airborne high-resolution hyperspectral images of a pine-dominated region in southeast Norway heavily attacked by the Pine sawfly Neodiprion sertifer, leading to severe defoliation. Leaf Area Index (LAI) is used as a proxy of the crown density, and comparing LAI maps from before and after the attack lead to indicators for damage extent. We discuss the application of the Forest Reflectance Model (FRT) of Kuusk and Nilson, which was designed for the application to (managed) Northern European Forests, to model the spectral response from the canopy. It is based on conventional forest inventory data, species-dependent parametrized crown shapes, canopy LAI, needle clumping index, and needle optical properties. Here, however, we run the model in an inverse mode, by iteratively minimizing the discrepancy between measured and simulated reflectances, and predicting the LAI, keeping known parameters of the model fixed. The LAI values are then compared to those obtained with either ground-based Licor LAI2000 measurements, or with airborne laser-scanning. Some preliminary results of this modelling concept for the case study are discussed.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Inge Stupak Antti Asikainen M. Jonsell Erik Karltun Anders Lunnan D. Mizaraite K. Pasanen H. Pärn Karsten Raulund-Rasmussen Dominik Röser M. Schröder I. Varnagiryte L. Vilkriste Ingeborg Callesen Nicholas Clarke Talis Gaitnieks Morten Ingerslev M. Mandre R. Ozolincius Anna Saarsalmi Kestutis Armolaitis Heljä-Sisko Helmisaari A. Indriksons L. Kairiukstis K. Katzensteiner Mikko Kukkola K. Ots Hans Peter Ravn Pekka TamminenSammendrag
The substitution of biomass for fossils fuels in energy consumption is a measure to mitigate global warming, as well as having other advantages. Political action plans for increased use exist at both European and national levels. This paper briefly reviews the contents of recommendations, guidelines and other synthesis publications on sustainable use of forest biomass for energy. Topics are listed and an overview of advantages, disadvantages and trade-offs between them is given, from the viewpoint of society in general and the forestry and energy sectors in particular. For the Nordic and Baltic countries, the paper also identifies the extent to which wood for energy is included in forest legislation and forest certification standards under the “Programme for the Endorsement of Forest Certification” (PEFC) and the “Forest Stewardship Council” (FSC) schemes. Energy and forest policies at EU and national levels, and European PEFC forest standards are analysed. With respect to energy policies, the utilisation of wood for energy is generally supported in forest policies, but forest legislation is seldom used as a direct tool to encourage the utilisation of wood for energy. Regulations sometimes restrict use for environmental reasons. Forest certification standards include indicators directly related to the utilisation of wood for energy under several criteria, with most occurrences found under environmental criteria. Roles and problems in relation to policy, legislation, certification standards, recommendations and guidelines, and science are discussed.
Sammendrag
River floods may cause considerable damage. Water management strategies intend tomoderate or mitigate the severe effects of extreme discharge events. In this context,techniques for the detection and attribution of changes is of crucial importance. Extremeflood events seem to occur more frequently in recent decades in central Europe.It is anticipated that climate change and weather regime shifts may contribute to this...