What do stable isotope measurements tell us?
Isotopes integrate, indicate, record and trace fundamental ecological processes. Rapid technological advances over the past decade have greatly stimulated the use of isotope analyses by ecologists. This analytical approach is now among the most popular in ecology because of the insights provided by isotope ratios at natural abundance levels. • Isotopes integrate ecological processes in space and time. The isotope ratios of plant and animal tissues and organic and inorganic compounds (including gases) in soil represent a temporal integration of significant physiological and ecological processes on the landscape. The timescale of this integration depends on the element turnover rate of the tissue or pool in question. In addition, the isotope ratios of well-mixed environmental reservoirs, such as the atmosphere, streams and aquifers, often represent an integration of source inputs to the system that extend over large spatial scales. • Isotopes indicate the presence and magnitude of key ec
