Components of nutrient residence time and the leaf economics spectrum in species from Mediterranean old-fields differing in successional status

1. Leaf life span (LLS) is one of the traits involved in the leaf economics spectrum (ranging from fast acquisition to efficient conservation of resources). How it relates to nutrient resorption efficiency (R-EFF), another key component of resource conservation, is still under debate. Here we test how leaf traits related to leaf economy, mass loss during senescence and R-EFF covary among species differing in resource use, and how they respond to nitrogen limitation. 2. Leaf traits were assessed for 18 species differing in successional status and in resource use, grown in a common-garden experiment under limiting and non-limiting N supply. 3. As expected, leaf traits and nutrient R-EFF vary with species successional status: early successional species have high rates of resource acquisition with high specific leaf area and live-leaf phosphorus concentrations, whereas late successional species have an efficient nutrient conservation with long LLS and high nutrient R-EFF. Leaf life span decreased under non-limiting N conditions, while nitrogen R-EFF was unchanged. 4. Leaf mass loss can alter assessment of nutrient R-EFF. Nutrient R-EFF was controlled by nutrient concentration in dead leaves and hence represents a process, distinct from leaf longevity, that leads to resource conservation.