Spenders versus savers: climate-induced carbon allocation tradeoffs in
an introduced woody plant
Non-structural carbohydrate (NSC) storage may be under strong selection
in woody plant species that occur across strong environmental gradients.
We therefore investigated carbon allocation strategies in a widely
distributed, introduced woody plant. We predicted genotypes from cold
climates with exposure to episodic freeze events, would have elevated
NSC concentrations with the tradeoff of reduced growth and reproduction
relative to warm-adapted genotypes. We established an experimental
common garden using genotypes of Tamarix spp., sourced across a large
thermal gradient within their introduced range. We measured seasonal NSC
storage in coarse roots and stems, above-ground growth and flower
production. Autumn NSC concentrations were 50% higher in genotypes from
sites with spring freeze events compared to genotypes from warmer sites.
Cold-adapted genotypes also had a 2.3-fold higher starch to soluble
sugar ratio than warm-adapted genotypes. Across all genotypes and
seasons, NSC storage was inversely correlated with growth and
reproduction. Results suggest that Tamarix from colder locations cope
with freeze events by maintaining large storage pools to support tissue
regrowth, but with the tradeoff of reduced growth and reproduction.
Results provide evidence of selection in carbon allocation strategies in
response to climate in introduced woody species.