LLEMS is an ecologically based decision support tool for assessing the implications of variable retention management for selected indicators of sustainable forest management. LLEMS will allow users to explore alternative variable retention systems by projecting the spatial and temporal development of complex cut blocks created by partial harvesting. LLEMS is designed to function in areas ranging from 10 to 1000 ha in size. LLEMS will include the following processes: light and nutrient competition, natural regeneration, ecotone or edge effects, understory vegetation, and windthrow disturbance. LLEMS will generate standard growth and yield output, forest attribute maps and summaries, 3D cutblock visualizations, and windthrow risk maps.