Plant resorption of nutrients from senescing tissues to growing tissues represents a key component of nutrient use and nutrient cycling. However, the evolutionary patterns of nutrient resorption remain unclear, particularly for herbaceous plants. Here, we present nitrogen and phosphorus resorption data from 27 Helianthus (sunflower) species grown in a common garden. We use phylogenetic mixed models to determine how nutrient resorption correlates with other leaf traits. To determine how nutrient resorption correlates with native site environmental characteristics, we assess resorption-climate and resorption-soil relationships. Specifically, we ask (1) How does nutrient resorption relate to other leaf economics traits? (2) How does nutrient resorption relate to leaf phloem and defense traits? (3) Does native site environment predict nutrient resorption?
Results/Conclusions
Nutrient resorption correlated positively with leaf structural investment, productivity, and chemical defenses, but not with phloem capacity. Nutrient resorption correlated positively with water availability, but generally was not predicted by soil fertility or nutrient limitation. Higher precipitation predicts higher nitrogen (but not phosphorus) resorption levels and therefore lower leaf litter quality, which has important implications for nitrogen cycling. Our results suggest that nutrient resorption has less to do with resource availability and more to do with plant growth rate and resource economic strategy, with resource-conservative species resorbing more than their resource-acquisitive congenerics.