Combining sciences and thoughts is essential for the sustainability of ecosystems as well as for understanding human life. Ecology, economics, chemistry, physics, climatology, informatics are pieces to be put together in order to compose the transdisciplinary picture of our complex world. This Volume contains the proceedings of the Sixth International Conference on Ecosystems and Sustainable Development that was held in Coimbra (Portugal) in September 2007. ECOSUD offers a unique opportunity and encourages the interdisciplinary communication between scientists, engineers and professionals working in ecological systems and sustainable development. The Conference objectives have evolved over the years, seeking to integrate thermodynamics, ecology and economics into "ecodynamics".The proceedings has been arranged in the following sections: Ecosystem modelling; Environmental management; Mathematical and system modelling; Environmental risk; Natural resources management; Sustainability indicators; Ecological areas studies; Energy and the environment; Socio economic factors; Sustainable tourism; Soil and agricultural issues; Sustainable waste management; and, Water resources.