Designing landscapes to support biodiversity requires more than adding greenery—it requires restoring the complex networks of species interactions that underpin ecosystem resilience. This principle, known as the reference ecosystem design approach, was the focus of a recent discussion organized by the ASLA Climate & Biodiversity Action Committee.
Chris Cosma, PhD, ecologist with the Conservation Biology Institute, explained that modern development, habitat fragmentation, and climate change have progressively removed “nodes” from ecological networks, contributing to global declines in insects, birds, and other species. Cosma emphasized that landscape architects can play a pivotal role in reversing this trend. By using at least 70% native plants, prioritizing keystone species, and designing for plant, structural, and phenological diversity, designers can reactivate these critical nodes. Additional practices—avoiding pesticides, reducing light pollution, and leaving leaf litter—further enhance habitat function.
Cosma highlighted that these design strategies do more than support biodiversity; they also improve ecosystem services such as air and water quality, carbon sequestration, and human health. His work underscores that thoughtfully designed landscapes can mimic natural processes, creating stable, resilient ecosystems even in urban and suburban environments.