In this contribution, the various and fundamentally different uses and applications of isotope signatures (of both heavy and light elements) are discussed. Examples are given for the successful use of87Sr/86Sr in uncovering fraud in wine trade. Also, in an experiment related to “Waldsterben”,87Sr/86Sr analyses reveal rather unexpected responses of spruces and maple-trees to mechanical damage of their roots. In another study, from206Pb/207Pb (and208Pb/207Pb) analyses of tree growth-rings it is demonstrated that they do not accurately record lead burdens in the environment. This is contrary to current views on the subject of tree-rings as reliable banks of past heavy metal pollutions of the biosphere. Furthermore, new perspectives of applications of isotopes in biological tissues, including those of cosmogenic and nucleogenic origin will be shortly outlined.