Event Title

Developmental Shifts in Functional Traits of Quaking Aspen

Event Website

http://www.nafew2009.org/

Start Date

23-6-2009 10:30 AM

End Date

23-6-2009 10:50 AM

Description

Quaking aspen is a clonal species that can produce suckers throughout its life cycle, resulting in multiple-age classes within a clone. Although each ramet in a clone is genetically identical, we hypothesize that there is physiological variation between the different age classes of the clone. This variation leads to phenotypic diversity, which may increase clonal fitness in response to selection forces. We conducted a study in seven pure aspen clones with 10 identifiable age classes that ranged from first year suckers to overstory trees >150 years old. We measured specific leaf area, leaf defense chemistry (tannins and phenolic glycosides), carbohydrate and leaf nutrients status, stem water potential and leaf photosynthesis. Each tree was aged by coring and then counting annual rings and clonal relationships were confirmed using microsatellite marker analysis. Phenolic glycosides decreased linearly with age, while condensed tannins increased. Photosynthesis and stem water potential declined markedly after age 40. The data suggests that aspen switch their defense strategy from resistance to tolerance once they grow above the mammal browse line, which may allow them to re-allocate resources from defense to growth. Reductions in photosynthesis and leaf water potential as clones age, may result in greater sensitivity to abiotic and biotic stresses.

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Jun 23rd, 10:30 AM Jun 23rd, 10:50 AM

Developmental Shifts in Functional Traits of Quaking Aspen

Quaking aspen is a clonal species that can produce suckers throughout its life cycle, resulting in multiple-age classes within a clone. Although each ramet in a clone is genetically identical, we hypothesize that there is physiological variation between the different age classes of the clone. This variation leads to phenotypic diversity, which may increase clonal fitness in response to selection forces. We conducted a study in seven pure aspen clones with 10 identifiable age classes that ranged from first year suckers to overstory trees >150 years old. We measured specific leaf area, leaf defense chemistry (tannins and phenolic glycosides), carbohydrate and leaf nutrients status, stem water potential and leaf photosynthesis. Each tree was aged by coring and then counting annual rings and clonal relationships were confirmed using microsatellite marker analysis. Phenolic glycosides decreased linearly with age, while condensed tannins increased. Photosynthesis and stem water potential declined markedly after age 40. The data suggests that aspen switch their defense strategy from resistance to tolerance once they grow above the mammal browse line, which may allow them to re-allocate resources from defense to growth. Reductions in photosynthesis and leaf water potential as clones age, may result in greater sensitivity to abiotic and biotic stresses.

http://digitalcommons.usu.edu/nafecology/sessions/aspen/7