Background and Objective

Scots pine is one of the most important tree species in Germany as well as in northern and eastern Europe. A controversy exists about the future of planting of Scots pine under the influence of climate change. Results of provenance trials are helpful to answer the question about the ecological amplitude of Scots pine. Therefore the IUFRO provenance trial with Scots pine from 1982 was measured and evaluated again. Analyses of increment of height and diameter growth could used to investigate how provenances have reacted to severe drought events.

Approach

11 of 20 provenances were selected at two sites of the 1982 IUFRO provenance trial with Scots pine. Three to five individuals per provenance in each of the four replicates at each site were cutted and used for analysis of annual increment of height and diameter. Annual growth parameters were modeled as a function of several time windows of moisture deficit (D) in a linear model. We analyzed individual tree tolerance to drought conditions using indices for resistance, recovery, resilience and relative resilience.

Results

Considerable differences in overall growth between provenances were observed at both sites. Basal area increment depended mainly on water availability from May to July, whereas annual height growth was influenced by moisture deficit during May of the current year.

The reaction to drought events was shown to depend on the timing and duration of the drought event. Differences between provenances in resistance were modest, but more pronounced for recovery and especially for resilience and relative resilience. The results indicate a better adaptation to drought of local German provenances compared to other provenances. We summarized the findings by aligning the eleven provenances between two multivariately defined archetypes, one of which represented best general performance defined by good overall growth, low climate sensitivity and high resilience to drought. This approach confirmed the superior performance of the local German populations. Provenances from France and Poland were ranked above average whereas northern provenances and that from Bosnia Herzegovina were found to be least suitable at the sites under investigation. Our results clearly demonstrate the importance of considering provenance in the discussion about future adaptedness and adaptability of tree species under climate change scenarios.