Coastal and interior Douglas-fir provenances differ in growth performance and response to drought episodes at adult ageReportar como inadecuado

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1 EEF - Ecologie et Ecophysiologie Forestières 2 INRA, UR0588

Abstract : & Context Since the 2003 drought and heat wave, Douglas-fir dieback has been reported in France in trees older than 30 years. Consequently, it is questioned whether selected Douglas-fir provenances are suited to the frequent and severe drought events which are forecast due to climate change. & Aims Our objective was to contribute to the screening of variability in productivity and growth response to soil-water deficit of mature trees from provenances not currently used for plantation in France. & Methods We sampled 22 provenances, including coastal and interior Douglas-fir, covering a wide part of its natural distri-bution, from Oregon to California for coastal provenances and from British Columbia to New Mexico for interior prove-nances. These provenances were planted at the mid 1970s in two provenance trials located in the south-west area of France. Variability of productivity, of wood density, and of radial growth in response to drought episodes among provenances was quantified and related to soil-water deficit computed by daily water balance calculations. & Results Whatever the provenance, annual radial growth is highly dependent on local soil-water deficit Felines R 2 = 0.57, Le Treps R 2 = 0.49. Radial growth and wood properties exhibit large differences between provenances at 30 years old. Variabi-lity between provenances for all wood characteristics studied is mainly structured geographically. Coastal provenances perform best for productivity at 30 years old 619 cm 2 ±59, and exhibit a small growth reduction in 2004, the second successive year of drought −10.7 %±3.8. Surprisingly, the southern interior prov-enances from the driest environments in the natural range show a large growth reduction in 2004 −30.5 %±5.2. & Conclusions The provenances tested exhibited significant differences in growth performance and growth reduction in-duced by the soil-water deficit. The approach coupling retro-spective analysis of radial growth on mature trees and water balance modelling is relevant for evaluating provenance ad-aptation to more frequent or severe drought episodes.

Autor: Anne-Sophie Sergent - Nathalie Bréda - Léopoldo Sanchez - Jean-Charles Bastein - Philippe Rozenberg -



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