资源环境科技发展态势分析平台

Context: Douglas-fir, a fast growing conifer from western North America, recently suffered diebacks following drought in France. We investigated the link between native-source climate and provenance drought resistance in a common garden in France. We compared the adaptive potential of provenances from different parts of the natural area.

Methods: We collected branches from a 25-year-old provenance trial replicated in two test sites in southern France. We estimated provenance variation of cavitation resistance traits, survival and circumference. We compared Washington-Oregon provenances to coastal and interior Californian provenances.

Results: In the common gardens, the hydraulic traits were significantly variable between provenances, with a strong site x provenance interaction, and significantly related to the climate of the natural area and survival. The relationships were different between variables and test-sites. The two test-sites and their particular climatic selective pressure revealed different geographical adaptive structures in the natural area.

Conclusions: Douglas-fir evolutionary adaptation to drought results from natural selection to summer climate and shapes populations for cavitation resistance. In the dryer site only, the Interior California provenances seem more drought resistant. The strong within-provenance variations suggest that there is also a certain withinprovenance adaptation potential to drought at the cost of variable mortality rates.