Article

Since a genetic resource is a col1ection of biological material containing either specific or particularly variable genetic variation, severa l cases can be found in European and Mediten'anean pine species that meet these requirements and might be included in gene conservation programmes. On the basis of their geographic distribution, European forest trees may show different pattems of variation among and within populations, as is il)ferred from isozyme markers: they may present several examples of populations carrying specific genetic variation that can therefore be looked upon as genetic resources. Other genetic markers (morphological, physiological and biochemical) are al so useful to indicate existing differentiation among populations and provenances. In this paper, some significant examples are given for the following species: Pinus sylveslris L., Pinus leucodermis Ant., Pinus nigra Am., Pinus cembra L., Pinus halepensis Mill. For each of them the proposed form of preservation is mainly the dynamic in situ conservation, which makes it possible to preserve the genetic adaptability of populations in changing environments.