Observational approaches in ecology open new ground in a changing world

Ecology has entered into a dynamic period, driven by both the urgency of large-scale ecological problems and startling new ecological findings that are being shared broadly beyond the scientific community. Both of these factors are well represented by observational approaches to ecology, which are re-emerging after a long period of deference to manipulative experimental approaches. These approaches examine ecological patterns and processes through data gathered in situations where nature has not been purposefully manipulated. The use of unmanipulated observational data reflects on the work of early naturalists, but is greatly enhanced by technological advances in remote sensing, microscopy, genetics, animal-borne sensors, and computing. Once dismissed as merely exploratory, strictly observational approaches to ecology have demonstrated capability in testing hypotheses by correlating variables, comparing observed patterns to output from existing models, exploiting natural experiments, and simulating experiments within large datasets. These approaches can be used in a stand-alone fashion, but are strengthened when reconciled with experimental manipulations to isolate fine-scale ecological mechanisms.