Ac. Finzi et al., CANOPY TREE SOIL INTERACTIONS WITHIN TEMPERATE FORESTS - SPECIES EFFECTS ON PH AND CATIONS, Ecological applications, 8(2), 1998, pp. 447-454
We quantified soil acidity and exchangeable cations in the forest floo
r and upper 7.5 cm of mineral soil beneath the canopies of individual
trees of six different species in a mixed-species forest in northweste
rn Connecticut. Soil pH decreased in a sequence starting with sugar ma
ple (Acer saccharum) > white ash (Fraxinus americana) > red maple (Ace
r rubrum) > beech (Fagus grandifolia) > red oak (Quercus rubra) > east
ern hemlock (Tsuga canadensis). The differences among species were lar
gest in the forest Boor and the top 7.5 cm of mineral soil. Exchangeab
le Ca and Mg in the 0-7.5 cm mineral soil layer were significantly hig
her beneath sugar maple than all other species, with the exception of
white ash. There were negligible differences among species in the quan
tity of exchangeable Ca and Mg in the forest floor. In the 0-7.5 cm mi
neral soil layer, exchangeable Ca was positively correlated with the c
ontent of unweathered Ca in the parent material, but the relationship
differed among species. There was a large increase in exchangeable Ca
in the soils beneath sugar maple but a negligible increase in the soil
s beneath hemlock and red maple. Exchangeable Al and Fe were highest b
eneath hemlock and lowest beneath sugar maple. The differences in pH a
nd exchangeable cations between sugar maple and hemlock are likely due
to interspecific differences in the introduction of acidity (e.g., or
ganic acids) and Ca uptake and allocation. Observing an association be
tween tree species and specific soil chemical properties within mixed-
species stands implies that changes in the distribution and abundance
of tree species alters the spatial and temporal pattern of soil acidit
y and cation cycling in this forest.