Short description
(English)
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Recent progress in fossil and DNA studies suggests that past tree migration rates were much slower than inferred from previous fossil records and far below what would be necessary for species migration to track future climatic warming. This is currently raising interest in the possibilities of translocation of tree populations (“assisted migration”) to areas where future climate might be favourable. We propose a well-replicated provenance experiment to investigate the question of whether or not beech of Mediterranean provenances will be able to naturally establish from seed in Central Europe under the present conditions of climate, with colder winters and higher probabilities of late spring frost.
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Partners and International Organizations
(English)
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AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GR, HR, HU, IE, IT, LT, LV, NL, NO, PL, PT, RS, SE, SI, SK, UK
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Abstract
(English)
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Natural migration of important tree species is probably slower than previously assumed, so trees might not be able to track changes due to climatic warming in the future. For that reason, there is rising interest in the possibilities and a debate about the shortcomings of assisted migration of tree populations. A temporally-replicated experiment was performed in dry mixed beech forests at three Swiss regions to test the establishment success of beech seeds of three Swiss, three Italian and one Slovenian provenance. Tree saplings in our experimental plots were monitored during one or two vegetation periods and provenance effects on survival and fitness assessed. Extreme spring drought in 2011 clearly affected both germination and survival of the plants in our experiment, which had major implications for data analysis. Consistent preliminary evidence was found at all sites of seriously hampered germination of the seeds sown in the second year, while one-year-old saplings, which had been sown in the first year, showed variable re-sprouting success among the three ex-perimental forest sites. Initial evidence was also found linking average summer precipitation at the mother tree's location and seedling survival under conditions of elevated arid time in spring at forest floor: seedling survival of provenances with low summer precipitation from Italy was better than sur-vival of provenances with high summer precipitation. In addition, a drought experiment under more controlled conditions at a tree nursery showed no effects of summer drought, but differences be-tween provenances in the fitness of saplings. Two Swiss provenances had the highest, two Italian provenances the lowest seedling growth at the nursery. The budburst of saplings from Italian prov-enances tended to be anticipated. We conclude that beech saplings of Mediterranean provenances may be more resistant to spring drought but bear an increased risk of late-frost damage under cur-rent climatic conditions in Switzerland. Based on preliminary evidence of significant differences be-tween trees within each provenance, we recommend rigorous long-term tests of more provenances, considering the progeny of more trees within each provenance and including a wide range of envi-ronmental conditions
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