Leaf habit and nutrient availability drive leaf nutrient resorption globally

Abstract. Nutrient resorption from senescing leaves can significantly affect ecosystem nutrient cycling, making it an essential process to better understand long-term plant productivity under environmental change that affects the balance between nutrient availability and demand. Although it is known that nutrient resorption rates vary strongly between different species and across environmental gradients, the underlying driving factors are insufficiently quantified. Here, we present an analysis of globally distributed observations of leaf nutrient resorption to investigate the factors driving resorption efficiencies for nitrogen (NRE) and phosphorus (PRE). Our results show that leaf structure and habit, together with indicators of nutrient availability, are the two most important factors driving spatial variation in NRE. Overall, we found higher NRE in deciduous plants (65.2 % ± 12.4 % , n=400) than in evergreen plants (57.9 % ± 11.4 %, n=551) , likely associated with a higher share of metabolic N in leaves of deciduous plants. Tropical regions show the lowest resorption for N (NRE: 52.4 % ± 12.1 % ) and tundra ecosystems in polar regions show the highest (NRE: 69.6 % ± 12.8 %), while the minimum PRE is in temperate regions (57.8 % ± 13.6 %) increasing to boreal regions (67.3 % ± 13.6 %). Soil clay content, N and P atmospheric deposition – a globally available proxy for soil fertility – and MAP played an important role in this pattern, where we found higher NRE and PRE in high latitudes. The statistical relationships developed in this analysis indicate an important role of leaf habit and type for nutrient cycling and guide improved representations of plant-internal nutrient re-cycling and nutrient conservation strategies in vegetation models.