Spenders versus savers: Climate‐induced carbon allocation trade‐offs in a recently introduced woody plant

Non‐structural carbohydrate (NSC) storage may be under strong selection in woody plant species that occur across broad environmental gradients. We therefore investigated carbon (C) allocation strategies in a widespread non‐native woody plant, Tamarix. We predicted that genotypes with exposure to episodic freeze events would show elevated NSC concentrations compared to warm‐adapted genotypes with the trade‐off of reduced growth and reproduction relative to warm‐adapted populations. We established an experimental common garden using genotypes of Tamarix, sourced across a strong thermal gradient within the 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 episodic spring freeze events compared to genotypes from warmer sites. These 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 trade‐off of overall reduced growth and reproduction. Our results are consistent with rapid selection in C allocation strategies in response to climate in introduced woody species. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.