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
Forfattere
Miguel D. Mahecha Markus Reichstein Holger Lange Nuño Carvalhais T. Grünwald Dario Papale G. SeufertSammendrag
Characterizing ecosystem-atmosphere interactions in terms of carbon and water exchange on different time scales is considered a major challenge in terrestrial biogeochemical cycle research. The respective time series currently comprise an observation period of up to one decade. In this study, we explored whether the observation period is already sufficient to detect cross-relationships between the variables beyond the annual cycle, as they are expected from comparable studies in climatology. We investigated the potential of Singular System Analysis (SSA) to extract arbitrary kinds of oscillatory patterns. The method is completely data adaptive and performs an effective signal to noise separation. We found that most observations (Net Ecosystem Exchange, NEE, Gross Primary Productivity, GPP, Ecosystem Respiration, Reco, Vapor Pressure Deficit, VPD, Latent Heat, LE, Sensible Heat, H, Wind Speed, u, and Precipitation, P) were influenced significantly by low-frequency components (interannual variability). Furthermore, we extracted a set of nontrivial relationships and found clear seasonal hysteresis effects except for the interrelation of NEE with Global Radiation (Rg). SSA provides a new tool for the investigation of these phenomena explicitly on different time scales. Furthermore, we showed that SSA has great potential for eddy covariance data processing, since it can be applied as a novel gap filling approach relying on the temporal correlation structure of the time series structure only.
Forfattere
Arne Evjen FønhusSammendrag
Det er ikke registrert sammendrag
Sammendrag
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Sammendrag
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Sammendrag
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Forfattere
Peder GjerdrumSammendrag
Predicting the yield and quality of sawn timber continues to be a challenging task, influenced by several stochastic processes: Log dimension and shape under bark varies, accuracy of sawing is not perfect, etc. This work presents an annotated model based on an approach successfully applied in the industry through a couple of decades. A number of important timber yield predictors are identified, and the following models give unbiased yield estimates. Being in need of adjustment before transferring to new locations, the approach might be considered a powerful tool to analyse and improve the operation, rather than a complete model in itself. Nevertheless, the notional, purely geometric, models might be superior for analysing unfamiliar sawing patterns, even if they tend to overestimate the yield. Thus, the two methods should preferably be used in combination, rather than one replacing the other. Finally, the everyday use of such models is illustrated and a procedure for associating sawn timber with suitable logs is outlined.
Forfattere
Anna Arneberg Per Holm Nygaard Odd Egil Stabbetorp Bjarni D. Sigurdsson Edda Sigurdis OddsdóttirSammendrag
The aim of this study was to investigate variation in decomposition and vegetation due to afforestation. The ICEWOODS sites containing stands of different tree species and age in the western (Skorradalur) and eastern (Hallormsstaður) parts of Iceland were investigated during the summer of 2004. These stands were compared with treeless pastures. The planted stands represent chronosequences, i.e., different age classes within each tree species were studied. Decomposition was studied by a cotton strip assay. Cotton strip decomposition increased with incubation time and decreased with soil depth. The tree species can be ranked according to increasing decomposition in the following series: lodgepole pine < Sitka spruce< Siberian larch < mountain birch. In general, decomposition decreased with increasing age of the stands...
Forfattere
Inge BjørdalSammendrag
Markslagsinstruksen er hovuddokumetasjonen på arealklassifikasjonssystemet som er nytta i Økonomisk kartverk. Den inneheld ein komplett oversikt over alle markslagsklasser, definisjonar, prinsippa for klassifikasjonen og reglar for praktisk kartlegging i felt. Instruksen har vore nytta heilt sidan oppstarten av markslagskartlegging, men har gjennomgått mange større og mindre revisjonar. Denne utgåva vert den siste sidan ein frå 2007 går over til å nytte AR5 i staden for DMK. Men markslagsinstruksen vil også vere det viktigaste kjeldematerialet til dette nye klassifikasjonssystemet.
Forfattere
Anders Often Harald BratliSammendrag
Det er ikke registrert sammendrag
Forfattere
Arne Fjellberg Per Holm Nygaard Odd Egil StabbetorpSammendrag
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