Controls on carbon and nutrient solubility in live and dead Betula pubescens leaves across a boreal retrogressive chronosequence.

1. Leaching – the release of elements from organic matter through dissolution in water – plays an important role in biogeochemical cycling and ecosystem processes. However, understanding the patterns in and underlying drivers of element solubility in leaves lags far behind that of other related plant traits. 2. In this study, we quantify the solubility of carbon (C), nitrogen (N), and phosphorus (P) from leaves of Betula pubescens - a widespread boreal tree species - across a 5182 year postfire retrogressive chronosequence. 3. We find that P is much more soluble than C and N, and is released in solution mainly in readily accessible mineral form. Solubility patterns are strongly related to foliar chemical and structural traits, particularly for green leaves, whereas metrics related to stand structure exert a stronger influence over solubility from senesced leaf litter. 4. Overall, our results indicate that leaching could constitute an important flux of nutrients to the soil, particularly of P, and that the rate and spatio-temporal pattern of this flux appear readily predictable from foliar and ecosystem properties. Further application of the method across more species and environmental contexts should allow for rapid integration of leaching-related foliar traits into broader plant trait frameworks.