The influence of forest stand composition on soil
was investigated by comparing the forest floor (FH)
and upper mineral soil (0–20 cm) nutritional
properties of jack pine and aspen stands on two soil
types of contrasting fertility, a coarse-textured and
a fine-textured deposit, in a replicated design. The
studied tree species are pioneers that are found
after major disturbances in the southern boreal
forest of western Quebec and that differ in their
nutrient requirements but not in their growth rate.
Soil organic matter as well as total and available N,
P, K, Ca, Mg contents were determined and the
relationships with nutrient accumulation in tree
biomass were studied. On both soil types a greater
total and available nutrient accumulation in the
forest floor layer was observed in aspen than in jack
pine whereas such differences between stand types could not be detected in the mineral soil. Differences
in FH nutrient content between stand types
were larger on coarse deposits than on fine-textured
soils. These results support the hypothesis
that tree species with greater nutrient requirements
cause an enrichment of the surface soil at least in
the short term. The modulation of tree species effect
by soil type was contrary to the pattern observed
in other studies since a greater expression of
this effect was observed on poorer soils. Differences
in soil nutrient content were related to levels of
organic matter accumulation.© 2007 Ecosystems.
