The scale of an ecological study affects what can be learned from it

Whether they study individual organisms or the diversity of life on Earth—or anything in between—ecologists always draw boundaries around what they observe. An ecologist interested in frog deformities might ignore the birds that migrate above the study site, while an ecologist studying bird migrations might ignore the details of what occurs in the ponds below.

When they seek to answer a particular question, ecologists must select the most appropriate dimension, or scale, in both time and space, for collecting observations. Every ecological study addresses events at some scales but ignores events at other scales. A study on the activities of soil microorganisms, for example, might be conducted at a small spatial scale (e.g., measurements might be collected at centimeter to meter scales). For a study addressing how atmospheric pollutants affect the global climate, on the other hand, the scale of observation might include Earth's entire atmosphere. Ecological studies also differ greatly in the time scales they cover. Some studies, such as those that document how leaves respond to momentary increases in the availability of sunlight, concern events on short time scales (seconds to hours). Others, such as studies that use fossil data to show how the species found in a given area have changed over time, address events at much longer time scales (centuries to millennia or longer).