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The Barnes' property
is located along the Kickapoo River, which, according to The Physical Geography of Wisconsin (Martin 1965 ), is the simplest and
largest stream in Wisconsin's Driftless Area. The vegetation of the
area consists mostly of southern hardwood forest and oak savanna as
described by Curtis (1959) in
his: The Vegetation of Wisconsin. As the river meanders through
the vast wooded hills and valleys on its way to the Wisconsin River,
lowlands rich in ephemeral wetlands, oxbow lakes and floodplain forests
can be found. These are the habitats that attract my attention on
visits to the area and that are the subject of this study.
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Fig. 1 A Small Oxbow Lake on the Barnes Property.
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As Curtis described,
the moist forests of southern Wisconsin result when the soil moisture
supply is in excess of that falling as rain. A useful key produced by
the Northern Prairie Wildlife
Research Center clearly identifies the moist forest of this study
area as a floodplain forest. Dominated mostly by silver maple (Acer
saccharinum ) and American elm (Ulmus americana), these are
the forests typical of such poorly drained areas. These floodplain
forests, according to Curtis, differ from the hardwood swamps of the
lake plains by characteristics relating to soil disturbance, variations
in water supply and the organic content of the soil. There are
opportunities to observe a succession of plant communities in the area
as the typical floodplain forest merges into those dominated by oaks
and hickories along the upland edges and even Sugar Maple (Acer
sacharum ) in the highlands. Hopefully these opportunities will be
points of later studies in the area.
I
am still in the early stages of studying the vegetation of this
area. Most of my efforts have thus far been directed toward the
taxonomy of its plants. To the present date I have identified two
hundred and seventy-two (272) plants in the area. In addition to the
taxonomic references listed in the references section I have found much
help in this effort at the Wisconsin
Vascular Plant web site. This web site, produced by the University
of Wisconsin at Madison, has links to the Wisconsin State Herbarium (a
site that contains a frequently updated list of vascular plants that
can be found in Wisconsin along with descriptions, range maps, and
other information useful for identification.) As plants were identified
it became obvious that they had to be separated into those of the
various habitats that I visited. A database (see KickPlants ) was established which
categorized them into plants of the roadside, open meadows, wooded
hills and floodplain. It must be recognized, though, that these
categories are somewhat artificial and often overlapping. Many of the
roads in the area are cut through very low areas subject to periodic
flooding and others pass through hilly woodlands. It is hoped, though,
that such designations will help to reveal certain patterns in the
distribution of the various species. In cases where identification to
species was uncertain, numbers of species were recorded so that the
species diversity could be approximated. To date, I have done no
quantitative sampling of the area.
The
trees of the floodplain area are sparse. Curtis suggests that "the
typical mature river forest of silver maple and American elm has only
about 85 trees/acre. The moist forests tend to have a very high total
basal area per acre due to the large size of the trees (rather than due
to density)." This, he says, is in part due to the low density of
seedlings resulting from poor conditions of germination. Although I
have no measurements to verify this, the trees in this study area seem
to be even further apart. Even in the middle of the growing season, I
never see a complete canopy that he suggests is maintained by the
spread of the large trees in spite of their low average densities.
Neither do I see the interlacing of the branches near the top of the
canopy of most of the trees. Many of the trees of the area do exhibit
the stooling (having multiple stems) he describes as a possible result
of the larger trunks dying off due to damage to the trunk bases by ice
flows and other flood carried debris during the spring period of
submergence.
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Fig. 2 Multiple Trunks (stooling) Typical of Floodplain
Trees.
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Thus
far I have identified one hundred and forty-nine (149) species of
vascular plants in the floodplain area; seventy-six (76) of which have
been found exclusively in the floodplain. At least one hundred and
twenty-two (122) of the species are native to the area. This number may
become higher as further identifications are verified. The vast
majority of the plants found in the floodplain have been herbaceous
perennials. This growth habit accounts for eighty-seven (87) of the
species identified while only eighteen (18) are herbaceous annuals. The
average species densities for the groundlayer species are low in the
wet forests. According to studies sited by Curtis, the same seven
families include 50% of the total species. These include Compositae,
Cyperaceae, Gramineae, Rosaceae, Labiatae, Ranunculaceae and Liliaceae
with the average presence for the prevalent species varying greatly
from stand to stand. The plants that I have identified thus far
represent fifty (50) families. Although my lack of taxonomic expertise
(especially regarding the grasses and sedges) limit the data in this
area, the Asteraceae [Compositae] (with 27 species) and the
Ranunculaceae (with 11 species) are the most represented among the
plants thus far identified. Lamiaceae (Labiatae) is represented by nine
(9) species. Fabaceae [Leguminosae] is also well represented (6
species) but it is interesting to note that all but one (1) of the
species of this family that have been identified are alien to the area.
A fairly rich spring flora develops in the wooded hills adjacent to the
floodplain areas with the many ephemeral wildflowers which are typical
of the woodlands in southern Wisconsin.
The wetland status for each of the one hundred and fourty-nine (149)
taxa found in the floodplain was determined by reference to the website
for the Wisconsin State Herbarium. Where these were not found, those
published in the 4th. edition of Plants of the Chicago Region ( Swink and Wilhelm, 1994
), were used. Twenty eight (28) of the plants were listed as obligate
wetland (OBL); meaning that they occur almost always (greater than 99%
of the time) in wetlands. Another thirty five (35) taxa were
facultative wetland species (FACW) which usually occur in wetlands
(67-99% of the time) but are occasionally found in non wetlands. Plants
equally likely to occur in wetlands as well as non wetlands (34-66% in
the wetlands), referred to as facultative (FAC) species were
represented by thirty four (34) of the taxa. Twenty eight (28) of the
taxa were listed as facultative upland (FACU) species meaning that they
were most likely to occur in non wetlands with a wetland frequency of
only 1-33%. Twenty four (24) were listed as obligate upland (UPL)
species because they occur in wetlands in other regions but occur
almost always in non wetlands in this region (wetland frequency less
than 1%).
Following methods described on the website of the botany department of
the University of Wisconsin-Madison,
each of Wisconsin’s native plants has been assigned a value for the
coefficient of conservatism. This value represents “an estimated
probability that a plant species is likely to occur in a landscape
relatively unaltered from what is believed to be a pre-settlement
condition.” Plants with low coefficients of conservatism are more
ubiquitous in their distribution and can be found in a variety of
habitats. Higher coefficients, however, are indicative of plants more
restricted to unique, native habitats. The coefficients for the plants
identified during this study can be found in the kickplants database.
Once assigned, the coefficients of conservatism can be used to estimate
the natural quality of an area. According to Swink and Wilhelm
(1994), “an area of high natural quality would have an array of
plants adapted to a diversity of micro-habitats and internal system of
interactions and responses.” Such an area would have a mean coefficient
of conservatism of five or greater. Degradation of an area would tend
to decrease the mean coefficient of conservatism. The mean coefficient
of conservatism for the 122 native plants identified thus far in the
floodplain during this study is 4.1. This would indicate considerable
degradation and would not be surprising given its history of
disturbance. That history includes periods of grazing by cattle as well
as clearing for a railroad right of way and residential dwellings.
Although these statistics can be used to derive further measures of
floristic quality, the methods used in this study do not warrant such
measures.
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Fig. 3 Laportea canadensis , Typical
Ground Layer Species of the Wetland Forest.
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Fig. 4 Cardinalflower (Lobelia cardinalis), an
obligate wetland species.
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In the short period
of time that I have been making observations in this area, it is
already apparent how the presence of the various species varies from
place to place and from year to year. The most obvious differences seem
to be related to the variations in the frequency and extent of flooding
in the area. Curtis related this to changes in the composition of the
dominant species of the groundlayer community from year to year. It is
also apparent in the height of the typical herbaceous plants in the
area. The Laportea canadensis never got as tall in the summer
of 2000 as it did in 1999 probably because of the longer duration of
standing water in the floodplain due to exceptionally heavy rains in
early 2000. Aggregation of the groundlayer plants is very pronounced in
the floodplain. As described by Curtis, " grasses, sedges and the two
nettles (Laportea canadensis and Urtica dioica ) form
dense colonies."
Both
woody and herbaceous lianas are abundant in the study area. In fact,
Curtis suggests that they have the highest presence value of any of the
understory species. Poison ivy (Rhus radicans ) is very abundant
on the trees of the study area. Other species identified in the area
include Virginia Creeper (Parthenocissus quinquefolia ) and
grape (Vitis sp.) among the woody vines and Hog Peanut (
Amphicarpa bracteata ) and Bur Cucumber ( Sicyos angulatus )
among the herbaceous varieties. Many of the trees can be seen to bear
more than one liana, many of which climb high into the tree.
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Fig. 5 Smilax sp. and Vitis sp. - Lianas of the
floodplain forest.
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True shrubs
contribute little to the understory of the lowland forests and these
have been little studied thus far in the area. A number of trailing
perrenial shrubs (brambles) have been found but these seem to be
confined to the higher regions of the floodplain such as along the
railroad right-of-way and the areas where the floodplain gives way to
the more upland wooded hills which border it. Buttonbush (
Cephalanthus occidentalis) has been seen growing along one of the
small oxbow lakes of the area but, like the cryptogams to follow, the
shrubs need more attention in the study area.
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