The contribution of leaf sulfur content to the leaf economics spectrum explained by plant adaptive strategies

Abstract

Sulfur is an essential macronutrient for plant metabolism. Terrestrial ecosystems have faced extensive anthropogenic sulfur depositions during the 20th century, but currently decreasing trend of sulfur emissions suggest that it could become limiting, although its relationship with plant economics remains unclear. We analysed leaf and nutrient traits for 740 vascular plant species growing in a wide range of environmental conditions. We aimed to determine whether leaf sulfur content (LSC) is associated with the leaf economics spectrum, and whether its distribution among functional types (life forms, leaf life span categories, and Grimes CSR (Competitive, Stress-tolerant, Ruderal) strategies) could help to elucidate adaptive differences within plant taxa. High LSC values corresponded mainly with R-, and to a lesser extent C-, strategy selection, hence the acquisitive extreme of plant economics. We found evidence of a relationship between nutrient stoichiometry and taxonomy, specifically at the acquisitive and conservative extremes of leaf economics. In general, LSC was significantly and positively correlated with leaf nitrogen content, but ruderal strategies in particular exhibited greater sulfur to nitrogen ratios. Faced with a dearth of LSC data, leaf nitrogen content could thus be used as a coarse proxy of LSC within the context of plant economics. Different ratios among sulfur and nitrogen may be expected for ruderal species, suggesting that deeper insights from CSR strategies can provide a bridge between plant stoichiometry and ecology.