The concepts of time and space are very important for understanding the function of phenomena in the natural world. Time is important to Physical Geographers because the spatial patterns they study can often only be explained in historic terms. The measurement of time is not absolute. Time is perceived by humans in a relative fashion by using human created units of measurement. Examples of human created units of time are the measurement of seconds, minutes, hours, and days.
Geographers generally conceptualize two types of space. Concrete space represents the real world or environment. Abstract space models reality in a way that distills much of the spatial information contained in the real world. Maps are an excellent example of abstract space. Finally, like time, space is also perceived by humans in a relative fashion by using human created units of measurement.
Both time and space are variable in terms of scale. As such, researchers of natural phenomena must investigate their subjects in the appropriate temporal and/or spatial scales. For example, an investigator studying a forest ecosystem will have to deal with completely different scales of time and space when compared to a researcher examining soil bacteria. The trees that make up a forest generally occupy large tracts of land. For example, the boreal forest occupies millions of hectares in Northern Canada and Eurasia. Temporally, these trees have life spans that can be as long as several hundred years. On the other hand, soil bacteria occupy much smaller spatial areas and have life spans that can be measured in hours and days.