Optimization of landscape mosaics is a theme that involves both compositional and configuration features. This paper just deals with the first problem: may we say what are the optimal proportions of different habitats in a mosaic under specified criteria? Environmental economists claim that landscape changes reflect monetary values and utility maximization or, in more general terms, maximization of expected subjective utility. Theory of Relevance advocates strategic reasoning in terms of the maximization of information and the minimization of the cognitive processing effort, and that could be assessed with a mathematical formula as far as it conveys some semantic insight over the compositional problem of the mosaic. Contributive value is a notion that goes back to Kant moral duty statements and may be approached through quantitative procedures that internalize both intrinsic and context values. Under that perspective Kw index here discussed may help assessing quantitative scenarios of the compositional problem of the landscape mosaic. I exemplify with an application with economic data relative to the region of Nisa, Portugal.