Exotic Abies species in Czech provenance trials: assessment after four decades.
The growth of seven exotic true fir (Abies) species and native Abies alba have been compared in three provenance trials in the Czech Republic, at the relatively advanced ages of 44, 38, and 35 years respectively. A clear differentiation is observable between the species. The closely related species group of A. alba and A. cephalonica appears rather heterogeneous in its phenotypic behavior. A. alba provenances show superiority, but also a high differentiation. Productivity of provenances of A. cephalonica fall behind A. alba; however A. cilicica and A. pinsapo provenances have shown total mortality. The high potential of A. grandis is confirmed by outstanding growth; provenances from the coastal plain in Washington State performed best. A. procera grows slower than A. grandis, but still faster than A. alba provenances. Health risks, extreme ecologic distances of transfer, trend shifts of growth rate, and rank change with age are uncertainties that require necessary caution when selecting provenances for importation. In recent years, public and institutional perceptions concerning the introduction of non-native tree species and provenances has shifted, and the practice is no longer seen as necessarily inappropriate.