drought reistance of douglas fir
TRANSCRIPT
Climate-Related Genetic Variation in Drought Resistance of Douglas-fir Sheel Bansal, Constance A. Harrington, Peter J. Gould and J. Bradley St. Clair
USDA Forest Service, Pacific Northwest Research Station
Results and Discussion • Populations originating from warmer and more
arid climates had relatively high drought resistance (i.e., lower transpirationmin, water deficit and SLA), but these trends were expressed only at the warm common garden.
• Contrary to expectation, populations from climates with relatively cool winter temperatures also had greater drought resistance across all gardens.
• Multiple regression analyses showed that drought-related traits could be predicted from minimum winter temperatures and growing season precipitation of the location of seed sources.
Conclusion Douglas-fir populations from regions with relatively cool winters and arid summers, such as the California Sierra’s region and along the Cascade Crest, may be most adapted to cope with current drought and conditions that are expected in the future.
Materials and Methods • We conducted a genecological experiment with
35 seed sources (i.e. populations) of coast Douglas-fir (Pseudotsuga menziesii var. menziesii) growing at three common gardens.
• We collected twig samples (new growth) from 280 saplings at each common garden in summer 2012.
• We measured three plant traits associated with drought-resistance: minimum transpiration (transpirationmin), water deficit and specific leaf area.
• Correlation and regression analyses were used to model trait values as a function of seed-source climate.
Transpirationmin
• Seal end of twig with wax • Measure twig weight daily • Transpirationmin= Slope of drying curve
00.20.40.60.8
11.21.4
0 5 10
Twig
wei
ght (
g)
Days
Mass loss/time
Water deficit
• Twig fresh weight (FW) • Twig end in water, turgid weight (TW) • Dry twig weight (DW) • Water deficit= (TW-FW)/(TW-DW)
Specific leaf area
• Needles photographed • Leaf areas (LA) with Image J • Dry weight (DW) • Specific leaf area= LA / DW
Drought-related ecophysiological traits
Introduction • Adaptation to local climates is a major driver of
variation in drought-related ecophysiological traits among intra-specific populations.
• As drought conditions become more common, ecologists and forest managers need to know which populations are most/least resistant to drought stress.
• Genecological, reciprocal transplant studies can reveal how climate influences drought resistance, and these data are used to model genetic variation in drought resistance across the niche space of a species.
Transpirationmin
Climate-related genetic variation in transpirationmin of Douglas-fir in the Pacific Northwest, USA. • Lower values (redder colors) indicate
populations with greater drought resistance.
Sheel Bansal Postdoctoral Research Ecologist Olympia Forestry Sciences Laboratory Olympia, Washington 98512 [email protected] [email protected]
What is climate-related genetic variation? Populations growing in the same environment (a common
garden) can have very different phenotypes depending on the climate of the location where seeds were collected.
Seed source from dry climate (California Sierra)
Seed source from wet climate (Oregon Coast)
Example: 2 populations in a common garden
(●) 35 seed sources () 3 common gardens Cool
Moderate
Warm
Genecology, reciprocal transplant study
All sources planted at each common garden
We thank the BLM for financial support