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.
2005
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Harald BratliSammendrag
Kartlegging av biologisk mangfold er foretatt i Oppegård kommune. Til sammen 155 lokaliteter er kartfestet og beskrevet, fordelt på 21 ulike naturtyper. Flest lokaliteter ble registrert i naturtypene rik sumpskog, småbiotoper, rik edelløvskog og gammelskog. Lokalitetenes verdi er vurdert. Til sammen 16 lokaliteter er gitt verdien svært viktig, 45 er rangert som viktige, mens 94 har lokal verdi. En høy andel lokaliteter med dammer og rik sumpskog ble vurdert som svært viktige. En oversikt over kjente forekomster med truede og sjeldne arter er også gitt.
Forfattere
Kåre HobbelstadSammendrag
Det er ikke registrert sammendrag
Forfattere
Anders BrynSammendrag
Det er ikke registrert sammendrag
Forfattere
J.A. AskSammendrag
Det er ikke registrert sammendrag
Forfattere
Toril Drabløs Eldhuset Holger Lange Nicholas Clarke Per Otto Flæte Erlend Ystrøm Haartveit Gro Wollebæk O. Janne KjønaasSammendrag
Root and needle litter are the most important sources of organic carbon in forest soils. Their decomposition is thus important for the long-term storage of C in, and release of CO2 from, the soil. Different components in the organic matter will decompose with different speeds. NIRS (Near InfraRed Spectroscopy) is a relatively simple and promising way of analysing the composition of organic matter, but its use in forest soil and litter studies has been limited up to now. We will present preliminary results from litter decomposition studies in two forest ecosystems: Picea abies stands (30 and 120 years old) from Nordmoen, Norway, and uneven-aged P. abies stands with a mean age of 90 years and under different N treatments at Gårdsjön, Sweden. ags with litter collected from the stands have been buried in the soil for different time periods and have been analysed using a CHN-analyzer and NIRS. Two aspects will be discussed: a) model calibration and validation for C and N concentrations, and b) assessment of decomposability using NIRS.
Forfattere
J. Jacobs Halvor Solheim Brenda D. Wingfield Michael J. WingfieldSammendrag
The genus Leptographium was described in 1927 and currently includes 48 species, with L. lundbergii as the type species. In recent years, the taxonomic status of L. lundbergii has not been uniformly agreed upon and it has been the topic of considerable debate. The problem was compounded by the absence of a type specimen, and the species was epitypified at a later stage. Unfortunately, the whereabouts of the epitype is now unknown. In 1983, Wingfield & Marasas described L. truncatum, which is morphologically similar to L. lundbergii. Based on DNA comparisons and similarities in their morphology, this fungus was reduced to synonymy with L. lundbergii. The loss of the type specimen as well as variation in the morphology of strains identified as L. lundbergii prompted us to re-examine the taxonomic status of this species. A number of strains from various geographic areas were studied. These include a strain of L. lundbergii deposited at CBS by Melin in 1929 (CBS 352.29) as well as the ex-type strain of L. truncatum. The strains were compared based on morphology and comparison of multiple gene sequences. Three genes or genic regions, ITS2 and part of the 28S gene, partial â-tubulin and partial elongation factor 1-α were compared. Strains currently identified as L. lundbergii, represented a complex of species. Strains initially described as L. truncatum clustered separately from other L. lundbergii strains, could be distinguished morphologically and should be treated as a distinct taxon. L. lundbergii is provided with a new and expanded description based on a neotype designated for it. A third group was also identified as separate from the main L. lundbergii clade and had a distinct Hyalorhinocladiella-type anamorph, described here as H. pinicola sp.nov.
Forfattere
Birger VenneslandSammendrag
During the 1980s Norway was troubled with overcapacity in the agricultural sector. The rural development support scheme (RDSS) was introduced. Farmers were encouraged to invest in forestry-related projects and rural business. More than 15 evaluations of the RDSS are undertaken, all of them having severe methodological weakness. The following study introduces a new tool, when analyzing a public support scheme like the RDSS in Norway. Data envelopment analysis (DEA) is a multi-input, multi-output optimization model used to measure relative efficiency of the best practice counties. The analysis is a two-stage study. In step one, it is found that 13 of the 18 (72%) counties in Norway are generating less output in the form of employment from a given level of the RDSS-budget than technically possible. In step two, a reallocation of the budget is shown for the purpose of maximizing the output of job establishments in rural Norway. The DEA is seen as a useful tool in measuring the efficiency of the RDSS at regional level in Norway.
Forfattere
Jon Frank Ingvald Røsberg Petter NilsenSammendrag
Project report to SNS project. Describes the methods for calculating C storage in Norwegian forests. Overview of the C-storage in forests and changes over time. Describing projects that can influence the Norwegian LULUCF reporting.
Forfattere
Bjørn ØklandSammendrag
Ips typographus is considered the most destructive of the bark beetles in the coniferous forests of the Palaearctic region. At low population densities this species breeds in fresh windfalls or dying trees of Norway spruce. At high densities, in contrast, the beetles may show tree-killing outbreaks at regional scales. Spatio-temporal analyses based on pheromone trap data indicated that large windfall events may be a major instigator and synchronizer of beetle outbreaks in areas subjected to regionalized weather systems. The general dominance of lag 1 density dependence of the time series indicated that the beetle populations are constrained by intraspecific competition for breeding substrates. The time series sequence before the large windfelling of 1987 was however declining without significant density dependence. We suggest this to be a transition period, reflecting a drop in carrying capacity due to depletion of susceptible trees during the preceding outbreak period (1970s) and a drop in beetle number to below the density required to kill trees. A variety of organisms exhibit episodes of explosive population growth, triggered by disturbance events. A new general model is constructed to capture the coupling of disturbance events with resource accumulation / depletion. The model is refined and parameterized using the dynamics of the Ips typographus in Scandinavia as a model system. The waiting times between outbreaks of simulated time series were generally longer and more variable than the outbreak lengths, which agree well with the historical records in the last 250 years. Spectral analysis and logspline density plots of waiting times suggest that the transition from aperiodic to periodic population dynamics should be regarded as a continuum.