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.
2004
Sammendrag
Ecosystems as objects of natural sciences are often difficult to understand, as an object of traditional management they are sometimes easy to utilize. Computer-based modeling offers new tools to study this apparent paradox.We propose an interactive framework from which the traditional approach based on dynamic system theory can be challenged for living systems: Models derived on the basis of the state concept have not (yet?) allowed predictions that derive novel management competence relevant for the altered boundary conditions of ecosystems. Here a concept of interaction as currently used in information sciences serves as starting point for deriving models more appropriate for ecosystems.An application and test of this concept consists in a search for signatures of interaction in environmental and ecological time series. Confronted with the notorious lack of detailed process understanding, it is plausible to rely on time series analysis techniques. The intricate nature of typical multivariate data sets from ecosystems immediately suggests a preference for nonlinear techniques, and among them temporally local methods, able to detect even subtle changes in the underlying dynamics.We shortly introduce a couple of these methods, which have been demonstrated to be appropriate for time series exceeding minimal length requirements. This is exemplified by recurrence quantification analysis. In addition we present methods to quantify the memory content (Hurst analysis) and complexity of data sets (defined in an informationtheoretic context).Time series analysis of extended environmental and ecological data sets can give detailed structural insights, monitors subtle changes undetectable otherwise, forms the basis for further inferences and provides rigorous model testing on all scales. The success of dynamic system theory when applied to non-living environmental data is strikingly contrasted by the difficulties of the same method when dealing with ecological data We conjecture that this difference reflects the extent to which interaction has been disregarded for ecosystems.
Sammendrag
The process of model building in the environmental sciences and when dealing with ecosystems is discussed. Two types of modeling approaches need to be distinguished: An algorithmic one, which has been used traditionally in physics, meteorology, and other branches where biological degrees of freedom are either absent or neglectable; and an interactive one, which is a new framework in computer science and seems to be most suitable in cases where organisms (including humans) as agents in ecosystems are to be taken into account. The first modeling approach is exemplified by state models in dynamic systems theory and expresses the correspondence imposed by Natural Law between inferential entailment in a formal system and causal entailment in natural systems. Modeling is to be separated from simulation. Simulation is a less restrictive type of modeling in which the description of non-interactive behaviour is the purpose and no constraints on the correspondence to internal states are imposed. The second (new) modeling approach is exemplified by interactive simulation models. It is able to express the correspondence in behaviour imposed by engineering standards (or cultural norms in general) between documentation, training and application in interactive choice situations such as games or ecosystem management. It generalises the notion of simulation for interactive problems. In an idealised situation the strictest correspondence between behaviour in a natural and a virtual system is expressed as bisimulation. The principles for model building are shortly demonstrated with examples.
Sammendrag
The forest stand growth simulator TRAGIC (tree response to acidification in groundwater in C) which has been developed to serve as a decision support system and a visualisation tool for scientists and forestry practitioners is introduced. TRAGIC places an emphasis upon visualisation techniques while at the same time providing detailed information on tree physiology and related parameters. The model is calibrated numerically to growth history data from two different European sites.Next, due to the importance of the visual component of the model, its ability to reproduce forest stand spatial structure is investigated, using an application of the theory of marked point processes. This analysis is applied to different experimental data sets for stands of different age, revealing information on planting schemes and the extent of significant spatial correlations.The spatial structure of the two model calibrations is then explored with the same methods. The point process analysis turns out to be a powerful diagnostic for model quality assessments, since spatial distribution is an indirect result of competition between trees for light.
Sammendrag
The notion of an ecological damage has so far neither been given a proper theoretical nor a pragmatic or operational foundation. Yet one of the most widespread motivations for the scientific study of ecosystems is a “protectional” one by which an improved scientific understanding is sought in order to be able to prevent future ecological damages. We review the possibilities of valuating changes in the environment, in health or in ecosystems as a damage. The conceptual separation of potential from actual behaviour/structure is a prerequisite to any of them. The critical point here is the formal and empirical basis for the knowledge about these potentials. We contrast the dynamic systems theory approach derived in physics with an interactive computing approach recently developed in computer science. The former requires to distinguish facts and values and leads to notorious difficulties when applied at the ecosystem level. The latter and novel approach opens the possibility for a consistent definition of a damage at the ecosystem level whenever a tradition of (sustainable) utilization of such systems is available. The documentation, actualisation and dissemination of the tacit (expert) knowledge can be improved by the use of interactive simulations in which a virtual standard can defined by the respective experts themselves.
Sammendrag
Rapporten inneholder et forslag til et system for å klassifisere arealdekke. Arealdekke er definert som det bio-fysiske dekket av landjorda. Et overordnet prinsipp for beskrivelse av arealdekke er å karakterisere fysiognomi og dekningsgrad. Landarealet er først inndelt i 8 hovedgrupper basert på 3 binære hovedkriterier. Disse 8 hovedklassene blir så videre karakterisert ved ulike sett av kriterier som gjelder for hver av de 8 hovedklassene. Kriteriene brukes for å lage standardiserte arealdekkeklasser. Systemet er fleksibelt ved at svært mange ulike klasser for ulike behov kan defineres. Et sett med definerte arealdekkeklasser for et gitt geografisk område kalles en tegnforklaring, og to tegnforklaringer for målestokkområdene 1:250.000 og 1:50.000 er foreslått for Norge. I tillegg er det gitt eksempler på spesielle tegnforklaringer for andre behov. Et sett med tilleggsattributter er definert for å gi tilleggsinformasjon som øker systemets tilpassing og korrelasjon med andre klassifikasjonssystemer som naturtyper, vegetasjonstyper, og habitattyper. Datafangst kan baseres på en kombinasjon av eksisterende kartdatabaser og tolking av bilder.
Sammendrag
NIJOS har analysert nøyaktigheten til en metode for flerkilde skogressurskartlegging (MSFI). MSFI bruker prøveflatedata fra Landsskogtakseringen, DMK, og et satellittbilde. Prøveflatene brukes som kalibreringsdatasett og data fra satellittbildet knyttes til alle flatene. MSFI beregner arealvekter til flatene i kalibreringsdatasett basert på hvor typiske de er for inventeringsområdet, som kan være et større område som en kommune eller et fylke. Mål på likhet baseres på data fra satellittbildet. For å finne nøyaktigheten til estimatene har en kryssvalideringsmetode blitt utviklet. Den estimerer prøveflatene en for en og beregner til slutt statistikk på nøyaktigheten. Metoden kan brukes til å justere parametere til MSFI og for å analysere feil. Resultater fra MSFI ble testet mot Landsskogtakseringens resultat for Østfold og en kontrolltakst for Hobøl kommune. Det ble konkludert med at MSFI er følsom for fordelingen i kalibreringsdatasettet. Hvis fordelingen til en bestandsparameter er vesentlig annerledes enn i inventeringsområdet, så vil det føre til relativt dårlige estimater. Årsaken er at bildedata ikke alltid skiller godt nok mellom de ulike parameterklassene. Med stort overlapp i bildeverdiene mellom to klasser, så vil den klassen som er representert med flest prøveflater bli tilsvarende mer vektlagt. Hvis kalibreringsdatasettet ikke er representativt mht. denne parameteren, så vil det føre til et dårlig estimat. MSFI kan forbedres med satellittdata som skiller bedre på parameterverdier som skal kartlegges.
Forfattere
Christer Magnusson Hans Overgaard Hans Nyeggen Karl Thunes Solveig Haukeland Bonsak HammeraasSammendrag
In this survey of 2002, 600 samples were collected from 83 forest blocks in the counties Akershus, Buskerud, Oppland and Østfold. The sampling activity involved 16 municipallities situated mainly within the three zone sites A, B, and C. Samples from Scots pine (Pinus sylvestris) formed 89%, while samples of Norway spruce (Picea abies) made up 10% of the total sample volume. Timber and forest debris were the most common objects sampled. Sixty-five percent of the pine samples and 81% of the spruce samples showed signs of Monochamus activity. Nematodes were common and occurred in 94% of the samples analysed. Thirteen samples of pinewood were positive for the genus Bursaphelenchus. Bursaphelenchus mucronatus was recorded for the third time in Norway, and was detected in forest debris attacked by Monochamus at Bjørdalen in the municipality of Eidsberg in the county of Østfold. The pine wood nematode Bursaphelenchus xylophilus was not detected in this survey.
Sammendrag
In this survey of 2003, 600 samples were collected from 96 forest blocks in the counties of Aust-Agder and Vest-Agder in southern Norway. The sampling activity involved 19 municipalities situated mainly within the two zone sites D and E close to Kristiansand and Arendal. Samples from Scots pine (Pinus sylvestris) formed 92%, while samples of Norway spruce (Picea abies) made up 8% of the total sample volume. Timber and forest debris was the most common objects sampled. Ninety-eight percent of the samples, regardless of tree species, showed signs of Monochamus activity. Nematodes were common and occurred in 90% of the samples analysed. Eight samples of pinewood were positive for the genus Bursaphelenchus. This genus did not occur in spruce. Bursaphelenchus mucronatus was detected in 6 samples of forest debris of pine attacked by Monochamus and collected in the county of Aust-Agder. In the municipality of Evje and Hornes B. mucronatus was detected at Skjerkelia and Sutestad. In the municipality of Froland the nematode was found in two samples from Budalsfjellet, and in one sample from Mjålandsvatn. In the municipality of Birkenes one sample from Vågsdalen contained B. mucronatus. This is the fourth report on the occurrence of B. mucronatus in Norway. The pine wood nematode Bursaphelenchus xylophilus was not detected.
Forfattere
Wendy Fjellstad Oskar Puschmann Wenche Dramstad Gunnar Engan Svein Johan Reid Jogeir N. StoklandSammendrag
NIJOS driver et nasjonalt program for registrering av tilstand og endring i jordbrukets kulturlandskap. Programmet er basert på kartlegging og statistiske analyser av et representativt utvalg jordbrukslandskap som dekker hele landet. Tilstandsregistreringen skal gjentas hvert femte år. Resultatene fra overvåkingen presenteres som et sett av indikatorer som beskriver tilstand til landskapets arealstruktur, biologisk mangfold, kulturminner og tilgjengelighet. Denne rapporten presenterer resultater fra Hordaland, Sogn og Fjordane, Møre og Romsdal, og Sør-Trøndelag.
Forfattere
Wendy Fjellstad Oskar Puschmann Wenche Dramstad Gunnar Engan Svein Johan Reid Jogeir N. StoklandSammendrag
NIJOS driver et nasjonalt program for registrering av tilstand og endring i jordbrukets kulturlandskap. Programmet er basert på kartlegging og statistiske analyser av et representativt utvalg jordbrukslandskap som dekker hele landet. Tilstandsregistreringen skal gjentas hvert femte år. Resultatene fra overvåkingen presenteres som et sett av indikatorer som beskriver tilstand til landskapets arealstruktur, biologisk mangfold, kulturminner og tilgjengelighet. Denne rapporten presenterer resultater fra Buskerud, Telemark, Aust-Agder, Vest-Agder og Rogaland.