Forest and natural ecosystem management operations are generally planned and implemented on individual land management units, at the community or ecosystem scale: field, plot, woodlot... But the effects of such operations on neighbouring units are often poorly taken into account. In addition, under changing environmental, regulatory, and economic conditions, it is increasingly important to address sustainable management at larger scales. Managers increasingly require advanced decision support tools (DSS = Decision Support Systems), such as expert and knowledge based systems, multi-criteria techniques as well as communication and visualization tools. Many models address environmental and ecological processes at the field, forest stand or agricultural activity scale, but they rarely capture interactions between farming, sylvicultural or ecological engineering practices and potential impacts on the landscape. In this presentation we shall outline some of the challenges modellers are facing in applied ecology, when moving upwards from plant to community and landscape. Several examples will be taken from recent and on-going integrated projects, focusing on decision support systems, aiming at improving connections between scientists and management practitioners for developing and implementing techniques in ecological engineering and ecosystem management.