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.
2002
Forfattere
Kjersti Holt HanssenSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Erik Næsset Tonje ØklandSammendrag
Tree height, the height from the ground surface to the tree crown, and the crown length as a proportion of tree height of individual trees were derived from various canopy height metrics measured by a small-footprint airborne laser scanner flown over a boreal forest reserve. The average spacing on the ground of the laser pulses ranged from 0.66 to 1.29 m. Ground-truth values were regressed against laser-derived canopy height metrics. The regressions explained 75%, 53%, and 51% of the variability in ground-truth tree height, height to the crown, and relative crown length, respectively. Cross-validation of the regressions revealed standard deviations of the differences between predicted and ground-truth values of 3.15 m (17.6%), 2.19 m (39.1%), and 10.48% (14.9% of ground-truth mean), respectively. On 10 plots with size 50 m2 in the boreal forest reserve and on 27 plots with size 200 m2 in a managed spruce forest, mean tree height, average height from the ground surface to the crown, and average relative crown length were regressed against laser canopy height metrics. The coefficients of determination (R2) ranged from .47 to .91. Cross-validation revealed a precision of 1.49 m (7.6%), 1.24-1.52 m (20.9-23.3%), and 6.32-7.11% (8.8-10.9% of ground-truth mean) for mean tree height, average height to the crown, and average relative crown length, respectively. At least, mean tree height can be determined more accurately from laser data than by current methods.
Forfattere
Johannes DeelstraSammendrag
Summary: The report describes the erosion problems in Subcuenca III, Managua, Nicaragua and proposes measures to alleviate these. Soil loss in the upper part of the catchment causes serious sedimentation in the downstream reaches of the open water courses, resulting in a reduced discharge capacity for water. This in its turn leads to flooding of urban areas during high rainfall periods and under extreme events can lead to closure of the international airport. In addition does the soil loss from agricultural land contribute in the ongoing deterioration of the water quality of Lake Managua while at the same time leading to a decrease in soil fertility and production capacity. An assessment is made of the present soil loss from agricultural land in the Subcuenca III and recommendations are proposed concerning soil conservation measures. Soil loss has been calculated using the Universal Soil Loss Equation (USLE). Very high figures for soil loss were obtained and the question has been raised whether these were realistic. However, the calculations were seriously hampered due to the lack of input data while at the same time were no data were available for validation.. Therefore, also proposals are given for a measurement programme to improve data availability and to be able to verify calculated soil loss. The report is translated from the original "Agro-hydrological study of Subcuenca III, Managua, Nicaragua." which is part of the "Estudio Agroecologico y de Drenaje Pluvial de la Subcuenca III de la Cuenca Sur del Lago de Managua
Forfattere
Wenche E. DramstadSammendrag
Det er ikke registrert sammendrag
Forfattere
Svein Solberg Line BreianSammendrag
De franske filosofene Deleuze og Guattari anvender det botaniske begrepet rhizomer i sin analyse av kultur og samfunn. Rhizomer er underjordiske stengelutløpere eller røtter som opptrer i et nettverk av møtepunkt i en åpen struktur uten hierarki. Vårt anliggende i denne artikkelen er å belyse styrken ved en rhizomatisk struktur med utgangspunkt i ugrasbiologi, for deretter å anvende dette på landbruk og fornyelser i landbruket.
Forfattere
Jan-Ole SkageSammendrag
Planting av fjelledelgran (Abies lasiocarpa) på ryddet skogsmark kan gi meget god etablering for plantene. Det viser resultater fra et radforsøk i Rogaland som Norsk institutt for skogforskning (Skogforsk) gjennomfører med 45 provenienser av fjelledelgran. Det var ikke behov for suppleringsplanting fordi hele 97,6 % av plantene etablerte seg. På skogsmark var det for øvrig også lite ugras som hadde hemmet plantene. Plantene på skogsmark etablerte seg bedre enn plantene i åtte andre forsøk, hvor det ble plantet på innmark, beite eller nydyrket mark. Imidlertid var det stor forskjell i både høydevekst og toppskader mellom proveniensene.
Forfattere
Geir Wæhler GustavsenSammendrag
Det er ikke registrert sammendrag
Forfattere
Tor MykingSammendrag
Additive variation in adaptive traits is a prerequisite for selection and adaptation to future environmental changes, but distribution of adaptive genetic variability between and within populations is poorly known in most forest trees. Owing to this deficiency, life history traits such as geographic range, pollination vector and seed dispersal capability, which significantly affect gene flow and thus the distribution of genetic variability, were used to evaluate the genetic resources in 23 Norwegian native forest tree species. Based on the combination of life history traits the species\" genetic resources were classified either as viable, potentially vulnerable or vulnerable, assuming a decrease in within-population variability in this sequence. Twelve widely distributed species with generally effective dispersal of pollen and seeds were considered viable (Pinus sylvestris, Picea abies, Juniperus communis, Betula pubescens, B. pendula, Alnus incana, A. glutinosa, Salix caprea, Populus tremula, Corylus avellana, Sorbus aucuparia, Prunus padus) and have as such no particular conservation needs. Effective seed dispersal of these species, as inferred from post-glacial migration rates, may be partly responsible for their generally early post-glacial appearance, and may, in combination with the wide ranges and relatively large evolutionary potential, indicate that viable species are best able to cope with climatic change. Among species with restricted ranges and more limited gene flow eight were considered potentially vulnerable (Quercus petraea, Q. robur, Fraxinus excelsior, Acer platanoides, Taxus baccata, Ilex aquifolium, Fagus sylvatica, Ulmus glabra) and three were considered vulnerable (Tilia cordata, Malus sylvestris, P. avium). Application of different intensities of a multiple population breeding system (MPBS) is considered the most appropriate mode of conserving genetic resources in these species.
Forfattere
Nina Heiberg Rigmor Standal Finn MågeSammendrag
I et sortsforsøk ved Planteforsk Njøs ble 20 sorter og seleksjoner vurdert på grunnlag av avling, bærkvalitet og flere vegetative karakterer i tre avlingsår. Sortene "Glen Ample", "Glen Moy", "Hitra", "Stiora" og "Tambar" anbefales for dyrking for friskkonsum i Norge.