Ecology of Red Maple Swamps in the Glaciated Northeast: A ...

inga by the following spring. Successful
red maple reproduction occurred primarily from
stump spmuts or mot suckers.
he mica^ and phyraial
Properties of Soils
The chemical and physical properties of soils
have been correlated with floristic variation of
forested wetlands in a number of studies (e.g.,
Monk 1966; Heinselman 1970; Messier 1980; Conner
et al. 1981; Huenneke 1982; Parsons and Ware
1982; Reynolds et al. 1982; Paratley and Fahey
1986; Dunn and Stearns 1987b). Among the soil
characteristics that have been related to swamp
floristics are nutrient status, pH, organic matter
content, and texture. Quantitative investigations
of the influence of such soil features on the flora of
red maple swamps are almost entirely lacking. For
this reason, the following discussion is based primarily
on qualitative information.
Nutrient status, which refers to the relative
abundance and availability of essential plant nutrients,
may be one of the most important soil
properties influencing the species composition of
red maple swamps. Nutrient status is closely tied
to hydrology, which in turn is shaped by the topographic
position or geomorphic setting of the wetland.
The swamp's setting determines the volumes
of groundwater and surface water it receives. The
chemistry of the water feeding the wetland is influenced
by the mineral composition of the local
bedrock and surficial deposits, the sources of water
entering the wetland, the slope of the surrounding
land, and the size of the wetland in relation to the
size of its watershed.
Nutrient availability within a wetland may be
affected by water regime and by the organic matter
content of the soil, which is largely a function of
water regime. In wetlands where soils are saturated
for much of the growing season, decomposition
of organic matter is slowed, and nutrients
such as nitrogen and phosphorus may be tied up
in undecomposed plant material. The retarded
growth of red maple on fibric (bog) soils has been
attributed to a shortage of such nutrients in a
continuously anaerobic soil environment (Moizuk
and Livingston 1966). Seasonal fluctuation of
water levels allows aerobic decomposition of organic
matter to proceed, releasing nutrients for
plant growth. As noted previously, thick deposits
of acid, nutrient-poor organic material may effec-
tively isolate plant roots from mineral-rich soil
layers beneath. Nutrient levels near the soil surface
also may be influenced by Sphugnurn moss,
which has the ability to extract bases from already
dilute soil water, lowering its pH (Moore and Bellamy
1974).
Damman and Kershner (1977) placed soil fertility
high on a list of factors (including disturbance
history and moisture regime) affecting species
composition of upland and wetland forests in western
Connecticut. Floristically rich red maple
swamps were encountered primarily where nutrient-rich
groundwater inflow was evident. They
noted that their study area contained a much
greater variety of plant communities than eastern
Connecticut landscapes with similar gneissic bedrock.
They conjectured that the possible incorporation
of calcareous material into the glacial till
deposited in their study area may have been responsible
for the greater floristic variation.
Groundwater flowing downslope along the upper
surface of bedrock or dense till layers could carry
calcium and other bases leached from upland soils
to lower slopes and valleys where it would be
deposited in wetlands.
Messier (1980) provided the most detailed discussion
to date on the influence of soil chemistry
on the floristics of red maple swamps. He gathered
data on floristic composition, water regimes, soil
fertility, and pH in 10 wetland communities in
northwestern Connecticut, including five types of
red maple swamps. Fertility was equated with
nitrogen availability and expressed as a carbon-tonitrogen
(C/N) ratio in his study. Assuming that
only organic matter with a C/N ratio of 20 or less
could provide direct mineral nitrogen to the soil
through decomposition, Messier calculated C/N ratios
for all communities and classified their nutrient
status as nutrient-pmr (W > 40), nutrientmedium
(C/N 20-40), or nutrient-rich (C/N < 20).
He noted that soil pH generally increased as the
C/N ratio declined, so pH also could be used as a
rough index of soil fertility
Of the 10 wetland communities examined, only
wooded bogs were classified as nutrient-poor; the
nutrient status of red maple swamps ranged from
medium to rich. The medium-fertility Osmunda
cinnarnomea-Acer and Rfmckdendron viscosurn-
Acer swamps had C/N ratios of about 20 at the soil
surface and 26-30 at a depth of 1 m. Messier noted
that the communities wiLhin this fertility range
were separated primarily by moisture regime. Soil
pH values for these two communities ranged from