Current issue: 56(4)
Under compilation: 57(1)
An ecophysiological growth process model, called INCA, for simulating the growth and development of a young walnut tree (Juglans regia L.) during three or four years, is presented. This tool, currently under development, aims at integrating architectural and physiological knowledge of the processes involved, in order to give a more rational understanding of the pruning operation. The model describes a simple three-dimensional representation of tree crown, solar radiation interception, photosynthesis, respiration, growth and partitioning of assimilates to leaves, stems, branches and roots. It supports the hypothesis that the tree grows as a collection of semiautonomous, interacting organs that compete for resources, based on daily sink strengths and proximity to sources. The actual growth rate of organs is not predetermined by empirical data, but reflects the pattern of available resources. The major driving variables are solar radiation, temperature, topological, geometrical and physiological factors. Outputs are hourly and daily photosynthate production and respiration, daily dimensional growth, starch storage, biomass production and total number of different types of organ. The user can interact or override any or all of the input variables to examine the effects of such changes on photosynthate production and growth. Within INCA, the tree entities and the surrounding environment are structured in a frame-based representation whereas the processes are coded in a rule-based language. The simulation mechanism is primarily based on the rule chaining capabilities of an inference engine.
Decision making in the forest protection involves diagnosing the pest, making predictions of the effects of the pest on forest, knowing the possible control tactics, and cost/benefit integration. To cope with all that, a generalist forest manager needs a tool like an expert system to support decisions.
This paper presents an expert system that approaches the goals of integrated pest management. With the systm, the user can make diagnosis and predictions of 12 North European bark beetles. Written in Common LISP and Flavors, the expert system has a combined frame- and rule-based knowledge representation. Frames are used to represent the hierarchy of insect taxonomy in diagnosis. Prediction is made with qualitative reasoning with rules. The interface engine applies both forward and backward chaining. The system has a graphical user interface that supports exploring the sensitivity of advice on input.
It is concluded that expert systems and artificial intelligence have high applicability everywhere in forestry where complicated decisions have to be made. Especially, an integrated pest management system in forestry is largely equivalent to a computerized decision-making aid.
The PDF includes an abstract in Finnish.
The article contains three presentations given about forest type classification at the University of Tarto in Estonia. The article has an introduction, a part about the meaning of the natural classification of forest sites and up to now conducted studies on site classification. The second part presents the characteristics of plant communities and the forest types, and practical and theoretical meaning of forest types.
Classifying the forest sites is important in practical forestry, because the forest growth and forest valuation are dependent on the productivity of the soil. The classification of the sites for forest management purposes needs to result in classes that are easily distinguished in the forest. This then leads to forest management that best fits to a certain forest site.
The article is a presentation given by the author on occasion of visit from Austrian timber industry and foresters (August 17th 1923), and again for the German visitors (August 20th 1923) in Punkaharju, Finland. The speech deals with the question of the overuse of Finnish forest compared to their growth. The developments of slash-and-burn-culture and forest inventories are described. The results of the inventories show, though still in preliminary state, that there is no nationwide overuse in total, though there are some locations where the felling are bigger than growth.
The article is a presentation given by the author on occasion of visit from Austrian timber industry and foresters (August 17th 1923), and again for the German visitors (August 20th 1923) in Punkaharju, Finland. The speech gives an overview of Finland’s forest resources region by region starting from far north. Also the most important uses and changes of forest as well as forest industry locations are mentioned.