Plant species effects on nutrient cycling: revisiting litter feedbacks

•The evidence is strong that foliar and soil nutrients covary across soil nutrient gradients. •Negative effects of N on litter decomposition weaken positive feedbacks to soil fertility. •Litter characteristics other than N and lignin can predominantly influence decomposition. •Root decomposition may reinforce positive leaf litter feedbacks to soil fertility. •The effects of plant species on soil organic matter dynamics deserve increased attention. In a review published over two decades ago I asserted that, along soil fertility gradients, plant traits change in ways that reinforce patterns of soil fertility and net primary productivity (NPP). I reevaluate this assertion in light of recent research, focusing on feedbacks to NPP operating through litter decomposition. I conclude that mechanisms emerging since my previous review might weaken these positive feedbacks, such as negative effects of nitrogen on decomposition, while others might strengthen them, such as slower decomposition of roots compared to leaf litter. I further conclude that predictive understanding of plant species effects on nutrient cycling will require developing new frameworks that are broadened beyond litter decomposition to consider the full litter–soil organic matter (SOM) continuum. In a review published over two decades ago I asserted that, along soil fertility gradients, plant traits change in ways that reinforce patterns of soil fertility and net primary productivity (NPP). I reevaluate this assertion in light of recent research, focusing on feedbacks to NPP operating through litter decomposition. I conclude that mechanisms emerging since my previous review might weaken these positive feedbacks, such as negative effects of nitrogen on decomposition, while others might strengthen them, such as slower decomposition of roots compared to leaf litter. I further conclude that predictive understanding of plant species effects on nutrient cycling will require developing new frameworks that are broadened beyond litter decomposition to consider the full litter–soil organic matter (SOM) continuum.