Decoupling of nitrogen and phosphorus release from fine and coarse roots
during seven years of decomposition
Abstract
Belowground litter decomposition represents an important source of the
limiting nutrients nitrogen (N) and phosphorus (P) to forest soils.
However, the rates and drivers of nutrient immobilization and release
from root litter remain poorly understood. To address this gap, we
conducted a seven-year field decomposition experiment using roots from
three species, across five diameter classes (up to 20 mm) in a temperate
forest. All roots released P to the surrounding soil within the first
year of decomposition but immobilized N for much longer, particularly
coarse roots. Long-term N release was mainly related to initial nutrient
stoichiometry of the substrate, whereas P release was better predicted
by substrate carbon (C) quality and decomposition rate. Initial root
nutrients well predicted the difference between long-term N versus P
release. Our results highlight the fact that N and P dynamics should be
considered separately when modeling nutrient release during root
decomposition.