Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2003
Authors
Kjell Andreassen Stein TomterAbstract
Distance-independent individual tree growth models based on about 30,000 observations from the National Forest Inventory and the Norwegian Forest Research Institute have been developed for the main tree species in Norway.The models predict 5-year basal area increment over bark for trees larger than 5cm at breast height. Potential input variables were of four types: size of the tree, competition indices, site conditions, and stand variables including species, mixtures and layers. The squared correlation coefficient (R2) varied from 0.26 to 0.55.The accuracy of the models was tested by comparing the individual tree models with Norwegian diameter increment models. The accuracy is similar, but individual tree models forecast diameter distributions directly. The inclusion of species mixture and layer as variables increases the reliability of the models in mixed and in uneven-aged stands
Authors
Harald Kvaalen Ola Gram Dæhlen Ulrika EgertsdotterAbstract
No abstract has been registered
Abstract
A multiplex real-time PCR assay was developed to monitor the dynamics of the Picea abies-Heterobasidion annosum pathosystem. Tissue cultures and 32-year-old trees with low or high resistance to this pathogen were used as the host material. Probes and primers were based on a laccase gene for the pathogen and a polyubiquitin gene for the host.The real-time PCR procedure was compared to an ergosterol-based quantification method in a tissue culture experiment, and there was a strong correlation product moment correlation coefficient, 0.908) between the data sets. The multiplex real-time PCR procedure had higher resolution and sensitivity during the early stages of colonization and also could be used to monitor the host.In the tissue culture experiment, host DNA was degraded more rapidly in the clone with low resistance than in the clone with high resistance. In the field experiment, the lesions elicited were not strictly proportional to the area colonized by the pathogen.Fungal colonization was more restricted and localized in the lesion in the clone with high resistance, hereas in the clone with low resistance, the fungus could be detected until the visible end of the lesion. Thus, the real-time PCR assay gives better resolution than does the traditionally used lesion length measurement when screening host clones for resistance.
Authors
Erlend Ystrøm Haartveit Dag FjeldAbstract
Efforts to improve efficiencies in the forest industries have mainly focused on problems within the borders of the company. Thus, there is an unexploited potential for increased efficiency through integrating and coordinating activities between companies. This poster presents games that mimic the forest industry and demonstrate to...
Abstract
The rationale for stand growth modelling is often either grounded in a search for improved scientific understanding or in support for management decisions. The ultimate goal under the first task is seen in mechanistic models, i.e. models that represent the stand structure realistically and predict future growth as a function of the current status of the stand. Such mechanistic models tend to be over-parameterized with respect to the data actually available for a given stand. Calibration of these models may lead to non-unique representations and unreliable predictions. Empirical models, the second major line of growth modelling, typically match available data sets as well as do process-based models. They have less degrees of freedom, hence mitigate the problem of non-unique calibration results, but they employ often parameters without physiological or physical meaning. That is why empirical models cannot be extrapolated beyond the existing conditions of observations. Here we argue that this widespread dilemma can be overcome by using interactive models as an alternative approach to mechanistic (algorithmic) models. Interactive models can be used at two levels: a) the interactions among trees of a species or ecosystem and b) the interactions between forest management and a stand structure, e.g. in thinning trials. In such a model data from a range of sources (scientific, administrative, empirical) can be incorporated into consistent growth reconstructions. Interactive selection among such growth reconstructions may be theoretically more powerful than algorithmic automatic selection. We suggest a modelling approach in which this theoretical conjecture can be put to a practical test. To this end growth models need to be equipped with interactive visualization interfaces in order to be utilized as input devices for silvicultural expertise. Interactive models will not affect the difficulties of predicting forest growth, but may be at their best in documenting and disseminating silvicultural competence in forestry.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Holger LangeAbstract
No abstract has been registered
Abstract
Reprints available in my office
Abstract
Living organisms in ecosystems are conceptualized as autonomous agents with a spectrum for their behavior. Ecosystems are described here as interacting multi-agent systems. Implementing such a system is a challenge for current hardware and software technology both technically and conceptually, in particular if one of the agents is human, either virtually within the system or as external participant and user (real human).Interfering with and manipulating the system occurs at arbitrary times during simulation, with a collection of choices to do that, rendering the details of the particular simulation fundamentally unpredictable.As a result, we have an open interactive system with tight feedback loops, for which new computer models (beyond the Universal Turing Machine) are required. We discuss some of the theoretical concepts for the appropriate software technology and shortly present one example of such a system, a forest simulator used by forest administrators.