Résumé (English)

The enormous computer science progresses of the past years open new perspectives for silvicultural management and give an opportunity to reconsider it as a whole. The clearly higher memory- and computing-capacities as well as efficient software for data processing make it possible to seize a forest ecosystem in its diversity and both in its spatial and chronological dimension. One can supplement the available software quite easily by programming new functionalities. With only relatively little effort the user interfaces can be arranged operator-friendly and interactively. This possibility allows keeping the development of efficient management instruments for forest ecosystems quite simple.

The result of this doctoral thesis is WIS.2, a software-product for an efficient and goal-oriented silvicultural management that is sustainable, close-to-nature and multi-functional.

• Goal-oriented in the sense that the forest managers consider expectations of the forest owners and of society, but aim particularly at implementing the strategy of the forest-enterprise, in which desired forest products and forest services are defined and set out in writing.
• Sustainable in the sense that soil-productivity is conserved and a demographic equilibrium of a stable and diversified tree population is reached. This diversity stands in relationship with the principle of distribution of risks and adaptability.
• Close-to-nature in the sense that one tries to achieve defined silvicultural goals by making use of natural forest dynamics as often as possible and attempts to restrict human interventions to a minimum.
• Multi-functional in the sense that on the same forest surface several forest products and services are produced.
• Efficiently in the sense that the potential of the forest site and the trees stocking on the stand is exploited in such a way that several effects (=>multifunctional forest management) are achieved at the correct site at the right moment with appropriate silvicultural interventions that are restricted to a minimum (=>close-to-nature).

The management of a forest ecosystem implicates that one subdivides it in spatial units of different size in order to render its goal-oriented use and structuring as a whole possible at all. Smallest one of these spatial units is the (forest-) stand that represents the basic unit of silvicultural consideration and management.

As much as the spatial dimension of silviculture, the dimension of time has to be considered, too. The slow growth of trees and their longevity require that on the occasion of each planning and each intervention a short-term, a middle-term and a long-term time horizon are included in the deliberation. The liberal and very pragmatic view of Swiss silviculture demands as few restrictions in planning as possible, in order to keep the scope in the forest as large as possible. This scope greatly matters, too, because one wants to satisfy short term pretensions to the forest (market tendencies) as much as one wants to reach the goals of the strategy of the forest-enterprise on a long-term basis.

In order to cope with these requirements, silvicultural planning necessitates a view that starts with “the rough” and goes to “the detail” in some sort of “zooming view”, starting from the whole forest perimeter with a long-term planning horizon (determined by public interests and the strategy) and coming to the determination and description of the short- and middle-term interventions on the level of the forest stand. This kind of view gets only possible through a significant description of each forest stand. To realize these stand descriptions one bases not on measured data, but on estimated, semi quantitative data. These data can then be aggregated for the characterisation of smaller units up to the bigger ones of the forest stand mosaic.

For the structuring of a system so complex the notion “management task” is very helpful. This term refers to a clearly limited problem of silvicultural management, for whose solution a decision is necessary. In a task competencies and resources (information, knowledge, method) necessary in order to make this decision are defined. The silvicultural management is regarded as one big task, which is to be subdivided in subtasks - starting with the “rough” (the whole forest) and going down to the hierarchically smaller spatial units until the smallest, the “detail” (the forest stand) is reached. This procedure allows to come to grips with the complexity of the silvicultural management by going through ensuing decision stages, in which one concentrates each time on the necessary and is delimiting and specifying at the same time the scope for decision-making of the following stages.

The structure that’s used for the “management-tasks” is also used for the user interfaces of WIS.2. The user of WIS.2 can move freely in the decision-making process of silvicultural management and is always able to keep track of the process because of its clearly structured arrangement. He disposes of the necessary resources in order to make decisions, to specify its scope, and to test different alternatives on the basis of computerised simulation. The organization and structuring of the tasks of management, starting with the rough and going into detail in WIS.2, highlights their mutual interaction. This is done so clearly that the tasks that lead to the changes and reciprocal effects can easily be recognized and adapted individually according to the order established by the system. The described accentuation renders it possible to operate a dynamic forest management that develops constantly with its environment, in order to remain functional. The use of information technology facilitates this dynamic management a lot. WIS.2 is a decision support system that consists of several applications. Each of these applications represents at each case a special domain of silvicultural management. Those are:

• The silvicultural analysis: Description of a forest area and its characteristics, notice of the possibilities and restrictions on the occasion of each silvicultural treatment.
• The forest products: Description and spatial representation of the relevance of forest functions, which possibly represent public interest and/or are included as desired products in the strategy.
• The silvicultural strategy: Implementation of the strategy, determination of a target state for the forest ecosystem that guarantees the production of the desired forest products in a sustainable way and combines them as suitably as possible (multi-functionality).
• The planning of forest regeneration and thinning: Implementation of the silvicultural strategy through the middle-term determination of regeneration measures and thinning-interventions on the level of forest stands in accordance with an intervention concept.
• In addition an application for updating and archiving of the data is on-hand, too.

WIS.2 is a prototype, which was developed for the “Mittelland of Switzerland and the group irregular shelterwood cutting system (also called ‘Schweizerischer Femelschlagsbetrieb’). Due to its modularity it is possible to develop applications for further regions and additional silvicultural modes of operation. The silvicultural information system is technically based on the relational data base-product ACCESS by Microsoft and the geographical information system ArcGIS by ESRI. The user interfaces are conceived in a way that users do not need knowledge of these two software products and can concentrate completely on silvicultural management.