Customizing ecosystem simulation applications is a complex operation, and t
he design of multi-agent systems remains expensive and error-prone. Object-
oriented frameworks are a promising technology for the reuse of proven desi
gns and implementation (i.e., software components and design patterns). Thi
s paper focuses on the design of agent-oriented, visual-interactive ecosyst
em simulations. We propose a customizable application framework, the novel
aspects being the use of new advanced software engineering techniques for t
he reuse of simulation models. The proposed framework is presented with the
Unified Modeling Language applied to complex ecosystems, with behavioral m
odels encapsulated into active autonomous objects with social interactions
(i.e., agents). The framework is also designed to support 2D or 3D visual-i
nteractive feedback to end users at run-time, in addition to its ability to
interface with Geographical Information Systems and the Web.