Strong disciplinary academic fragmentation and sectoral division in policies lead to problems regarding the management of landscapes. As a result, there is a focus on the preservation and development of either cultural or natural landscapes. We argue that framing landscapes as "natural" or "cultural" will not help sustainable management. The goal of this paper is to show that even what is referred to as nature, virtually always features an intricate combination of physical geography, biology, and cultural history. It provides an analytical framework that visualizes the three forces at play in physical landscapes. Therefore, we introduce a diachronic triangular approach to study and manage landscapes from a holistic point of view, allowing an exchange of different perspectives. To test this approach, we have applied our model to a diachronic case study on Wadden Sea salt marshes. That area has been influenced by physical-geographical, biological, and cultural landscape forces, which are still visible in the landscape to a large extent. By placing different landscape zones in the triangular concept for different time periods, we can identify and visualize these driving forces through time for this specific landscape. These all play their specific roles in the appearance of the landscape over time in a close mutual interconnection. More importantly, we show that the diverse and complex interplay between these forces makes the current-day landscape what it is. We therefore conclude that the diachronic triangular approach provides a conceptual tool to define and operationalize landscape management in the Wadden Sea area. We welcome similar approaches in other landscapes to assess the usefulness of the diachronic triangular landscape approach.