Genetics of Douglas-fir response to 2003 heat wave in France

MARTINEZ MEIER, ALEJANDRO; ROZENBERG, PHILIPPE; SÁNCHEZ, LEOPOLDO; DALLA SALDA, GUILLERMINA; PASTORINO, MARIO JUAN; GALLO, LEONARDO ARIEL

Ghent (Bélgica)

Conferencia; TRACE 2006 – The Annual Conference and General Meeting of the ATR; 2006

Association for Tree-Ring Research (ATR)

Extremely high temperatures were reached in several European countries including France during summer 2003, broking in some cases all-time maximum temperatures. The low precipitation during the same period failed to compensate for the evapotranspiration, creating an accumulative water balance deficit. Many trees were manifestly affected, from partial foliage necrosis to the death of individuals. Douglas-fir (Pseudotsuga menziesii) was one of the most affected species. During the growing season, cambial activity and characteristics of xylem cells deposited are affected by variation of water balance. Thus genetic variation of characteristics of wood formed in reaction to an extreme climate event like the 2003 heat wave can provide information about tree adaptation. This information can be used in tree breeding programs, for example to help select better-adapted genotypes. Simple microdensity characteristics of the wood formed during the 2003 growing season were compared among nine Douglas-fir clones installed in three different geographical locations, to the characteristics of rings 2002 and 2004, formed during normal years from the climatic point of view. Our results show that: (1) the heatwave impacted more one site than the other two, (2) in this site, all characteristics of the ring 2003 that we studied were significantly affected by the 2003 heat wave: the values of all ring variables except one significantly decreased from 2002 to 2003 (ring width, ring mean density, ring maximum density and within-ring density standard deviation). Only minimum ring density significantly increased from 2002 to 2003. On the contrary, the values of all ring variables but one (ring minimum density, which significantly decreased) significantly increased from 2003 to 2004. (3) The reaction of Douglas-fir to the 2003 heat wave and the 2004 recovery was described using between-successive-year differences for the ring variables. The results show that there is significant genetic control of tree reaction for all ring variables, except for ring maximum density between 2002 and 2003.