Interdisciplinary planning and evaluation of forest management is necessary for sustainable forest management (SFM) schemes involving multiple values of multi-stakeholders. Often, multi-objective forest-planning and evaluation encounter complexity and uncertainty due to "inexactness" - i.e., fuzziness, ambiguity, imprecision and variability - of spatial behaviours of ecological and human systems. This paper develops the possibility schema - from fuzzy sets and theory of possibility - for representation and evaluation of inexact spatial concepts, configurations, and processes, associated with forest ecosystem and stakeholder values. A hypothetical case of interdisciplinary research utilizing criteria and indicators of SFM is used to illustrate the utility of the proposed possibility schema in interdisciplinary forest decision-making. The schema can be used for ex-antc appraisal and ex-post evaluation of forest programs. It can also be used for intearation of interdisciplinary forest knowledge, including ecological and socio-economic models of SFM.