[en] The utilization of f-elements has a relatively minor status as a research tool in the biological sciences, especially ecology, because they play neither positive nor deleterious roles in plant and animal nutrition. Additionally, detection and quantification via instrumental neutron activation analysis (INAA) of environmental samples is not yet routine. At Louisiana State University, La, Sm, and Dy have been used successfully as activable stable tracers in a wide range of ecological studies including the quantification using Sm and Dy of short-term sedimentary and erosional processes in wetlands; and behavior studies using Sm on agricultural lands where radioisotopes are precluded; the sorption of Dy and La by roots of stream-side trees; and the quantification of exogenous Dy and Sm from animal decay products in streams. With advances in sample automation and standardization in INAA detection methods, the quantification of f-element tracers in complex biological matrices is within reach of ecological scientists