Mitigating climate change effects on forest growth using planting stock with high adaptive genetic capacity: results from Abies alba (Mill.) provenance trials at the southeastern distribution limit

European silver fir (Abies alba Mill.) is among the most important forestry species in Europe. In Romanian Carpathians, it covers about 5% of the forests area and almost two-thirds of its distribution is located in Eastern Carpathians, which is the southeastern edge of its distribution in Europe.
The most recent climate change scenarios for Europe suggest increases in mean annual temperature of 1-4 °C by the end of this century (Meinshausen et al. 2011). In the context of global warming, the populations living at the edge of the species distribution will be the first facing the climate change effects. In these regions, as the southeastern Europe, the main constrains are increasing the temperature, extended drought events and water availability. Forest species are particularly sensitive to climate change because the long life-span of trees does not allow for rapid adaptation to environmental changes (Lindner et al. 2010). 
In this context, the aim of this study was to analyze the drought response of 51 European silver fir populations from: Romanian Carpathians (26), Austria (4), Germany (3), France (3), Italy (4), Slovakia (3), Czech Republic (3), Poland (1) and Bulgaria (4)  to strong drought events which have occurred in this region, in the last 30 years. The populations are tested in three provenances trials established in Romania, in 1980; two of them being located outside and one within the optimum climatic of species. The most drought years, with severe or extreme drought periods, have been identified based on the standardized precipitation index (McKee et al. 1993). The growth response of the silver fir populations to the drought events was evaluated by calculating four parameters, namely: resistance, recovery, resilience, relative resilience (Lloret et al. 2011). Results reveled that the general trend was towards decrease the stem radial growth of silver fir during the last 30 years. The provenance x year interaction was not significant which means high provenances stability over time. Significant differences were found among silver fir provenances in terms of ring width, latewood proportion, resistance, recovery and resilience in drought years. There are provenances which have highlighted high productivity and high tolerance to drought, which could be used in reforestation work, breeding and conservation programs. The radial growth of silver fir provenances was negative affected by the temperature increase during vegetation period and positive by previous autumn-spring precipitations. Therefore, the forest management strategy to mitigate negative impacts of climate change should be based on the knowledge of the intraspecific genetic variation and selection of the best performing and adapted planting stock for each region.