This paper raises two major questions: (1) Do forestry operations modify genetic processes that would increase exposures of tree populations to future losses or hazards? (2) Do genetic activities per se (selection, tree improvement, biotechnology) lead to increase susceptibility to risks? A general frame for the analysis of genetic risks is first presented by outlining the effects of different genetic attributes or processes on the exposure or tolerance to risks. Then a review of the various risks generated by species of population transfer, silvicultural and management regimes, tree breeding activities and biotechnology is given. Main concerns in these activities are the potential erosion of genetic diversity, the strong modifications of the distribution of genetic diversity due to artificial seed flow, the disruption of genetic processes maintaining diversity, and the potential release of genetically modified trees. To cope with these concerns most countries and institutions have adopted conservative measures as dynamic conservation programmes of genetic resources.