Abstract
When characterizing the processes that shape ecosystems, ecologists increasingly use the unique perspective offered by repeat observations of remotely sensed imagery. However, the concept of change embodied in much of the traditional remote-sensing literature was primarily limited to capturing large or extreme changes occurring in natural systems, omitting many more subtle processes of interest to ecologists. Recent technical advances have led to a fundamental shift toward an ecological view of change. Although this conceptual shift began with coarser-scale global imagery, it has now reached users of Landsat imagery, since these datasets have temporal and spatial characteristics appropriate to many ecological questions. We argue that this ecologically relevant perspective of change allows the novel characterization of important dynamic processes, including disturbances, long-term trends, cyclical functions, and feedbacks, and that these improvements are already facilitating our understanding of critical driving forces, such as climate change, ecological interactions, and economic pressures.
Ecologists increasingly include remotely sensed measurements in their efforts to describe ecosystem states and dynamics, and the number and capacity of tools available is continually expanding. For example, ecologists can turn to a growing suite of very high spatial resolution (VHSR) products to describe plot-level conditions in two and three dimensions (Wulder et al. 2004; Vierling et al. 2011), and to imagers at the global scale to examine the ecological status of the entire biosphere (Justice et al. 2011). Although availability, cost, and spatial scale are critical factors when determining appropriate remote-sensing tools, ecologists attempting to move beyond descriptions of state and toward an understanding of dynamics must consider another critical issue: does a given remote-sensing tool describe change over time in a manner consistent with the ecological process of interest?