The change in the user requirements over the years, has underscored the need for the integration of multiple information sources into a single viable source. In Information technology, legacy systems and data are those that have been inherited from languages, platforms and techniques earlier than the current technology. Integration of such heterogeneous applications is a difficult task. This thesis proposes a framework called Open Intelligent Information System for Forestry Domain (OIISFD) for integrating such applications in the forestry domain. OIISFD contains three components, namely, the inference component, the knowledge component and the legacy component. The inference component contains application description knowledge ("what does the application do"), domain specific knowledge and a reasoning module for handling user queries. The knowledge component contains application specific knowledge ("how to run the application"), input/output criteria and special vocabulary associated with the application. The legacy component contains legacy applications with their wrappers. The entire framework is developed on COM/DCOM platform, with XML (Schema) being used for knowledge representation and for communication mechanisms between the different components.