Ecosystems in action: How free Landsat data are changing how we see landscapes

Ecosystems change continuously through internal processes, such as succession and growth, and external processes, such as wildfire or urbanization. Considered the workhorse of landscape monitoring, the Landsat sensors have long provided imagery to examine the manifestations of those processes by comparing landscapes before and after change. With the Landsat archive now freely accessible and approaching forty years in depth, however, new approaches are emerging that go beyond endpoint comparison towards full characterization of landscape dynamics. Using findings from our own work and others as examples, we find several important themes: 1. Anthropogenically-caused changes to landscapes can now be tracked at time scales commensurate with their ecological impacts and with their socioeconomic and policy drivers; 2. Long-duration mortality processes, such as those associated with drought and insect outbreaks, can now be tracked more effectively; 3. Long-duration growth processes, such as post-fire recovery, can also be tracked; 4. The entire time-series can be used to give greater insight into the causes of change and the state of the system at any given point. These promising themes lay the foundation for better monitoring and modeling of ecosystems in response to climate change, natural events, and anthropogenic pressures.