Study On Afforestation Decision Support Model Based On COM GIS

Afforestation is the principal part of production and management of a forestry centre (forestry station), especially those whose general attention is paid to ecological environment of forest both at home and abroad. Promoting and developing afforestation in a more cost-effective manner is primary for increase of forest resources and improvement of forest quality. It is also the main approach to supplementing of forest resource and constructing ecological environment and realizing forestry's sustainable development as well. With the carrying out of the six major projects, which is the great action of our country in forestry's ecological construction, it seems more important to design afforestation operation. Afforestation decision support model (ADSM), based on the development of GIS (Geographic Information System), DSS (decision support system), ES (expert system) and DB (database technique), is proposed and set up with a concrete goal of planning and designing afforestation. It is the foundation of intelligent, automatit, scientific and rationalized process in planning and decision of afforest and can offer the theoretical foundation for the setting up of afforestation decision support system.A decision goal is put forward according to the general course of afforestation planning in a forestry centre: choosing afforestation site, estimating site type, selecting tree species and afforestation techniques. As a result, the decision support model of afforestation site, the model of site type, the model of tree species, and the model of afforest technology have been studied and set up according to the influencing factors and concrete characteristics of every decision item. This paper shows the pattern of models' operation, the principles and constructure of the models by taking Fangshan District of Beijing as an example. The research results are follows:(1) ADSM was proposed and set up for the first time, consisting of afforestation site decision support model, site type decision support model, afforestation species decision support model and afforestation technique decision support system.(2) Systematic theory and set theory were innovatively suggested for construction of decision support model, of which the structure is aggregate-element-attribute-attribute set. The aggregate is made up of many elements, which are elementary cells of it. The attribute refers to the characters of an element in a certain respect, and when such characters are put together, attribute set is formed. In decision support model, an element shows characters in a certain respect of the decision object. It also shows the conditions of the decision target (the limited conditions of decision), while attribute is the value of the decision goal in a certain respect of target decision (decision result).(3)Mapping - the basic operational mode of model is proposed. All the decision results of the target are the mapping of its conditions determined by the decision scheme. Those are demonstrated in the following two respects: the mapping for the element-attribute within the set, which shows the knowledge reasoning of determined nature or quantitative data, generally appearing in the forms of plurality vs. plurality, single vs. plurality or plurality vs. single with more than one result; and the mapping for the mathematics function, which shows the quantitative equality operation of data, in the form of plurality vs. single (polyhydric), or single vs. single (one) with only one result.(4)The general reasoning engine, consisting of Structured Query Language (SQL) based on set theory and techniques of DB, was put forward. The basic structure of the decision support model: element of set, attribute of element and mapping between them, is related to the database, knowledge base and model house. To the afforestation planning and designing problems in any certain area, the data and knowledge are uncertain, while the mapping between them is certain. This kind of relation is reflected in the procedure and stored in the pattern of model, and therefore the general...