نبذة مختصرة : Nutrient resorption is a key strategy in plant conservation, which minimizes nutrient loss and enhances productivity. However, the effects of stand development and the neighbourhood species diversity on the nutrient resorption of boreal tree species remain unclear. Using a detailed, replicated chronosequence spanning 7, 15, 33, 98, 146, and 209 years following fire, we examined the dynamics of leaf nitrogen (NRE), phosphorus (PRE), and potassium (KRE) resorption efficiencies of two common broadleaved boreal tree species (Populus tremuloides and Betula papyrifera) associated with stand development and overstory composition type (monoculture and mix- edwood) in a central boreal forest of Canada. We found that the leaf NRE did not change; however, the PRE and KRE decreased with overstory succession. Further, we observed a higher leaf PRE in younger mixed stands, but a lower leaf PRE in older mixed stands, compared to monocultures for Populus tremuloides. Our results also revealed that the leaf NRE/PRE and NRE/KRE ratios increased with overstory succession, particularly in mixed stands, which demonstrated strong N limitations in old mixed boreal forests. Moreover, the overstory succession- and type-dependent dynamics of nutrient resorption efficiencies were driven by soil nutrient changes and relative tree growth rates associated with stand development. Nutrient resorption efficiency patterns may imply a transition from more P and K limitations in early succession, to more N limitations in late succession. Our findings highlight the need for modelling long-term primary productivity to account for overstory succession- and type-specific changes in nutrient resorption efficiencies.
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