Botkin Environmental Science Earth as Living Planet 8th txtbk

5.7 Ecological Stability and Succession 97
Bog Succession
A bog is an open body of water with surface inlets—
usually small streams—but no surface outlet. As a result,
the waters of a bog are quiet, flowing slowly if at all. Many
bogs that exist today originated as lakes that filled depressions
in the land, which in turn were created by glaciers
during the Pleistocene ice age. Succession in a northern
bog, such as the Livingston Bog in Michigan (Figure
5.16), begins when a sedge (a grasslike herb) puts out
floating runners (Figure 5.17a, b). These runners form a
complex, matlike network similar to that formed by dune
grass. The stems of the sedge grow on the runners and
carry out photosynthesis. Wind blows particles onto the
mat, and soil, of a kind, develops. Seeds of other plants,
instead of falling into the water, land on the mat and can
germinate. The floating mat becomes thicker as small
shrubs and trees, adapted to wet environments, grow. In
the North, these include species of the blueberry family.
FIGURE 5.16 Livingston Bog, a famous bog in the northern part
of Michigan’s lower peninsula.
Sedge puts out floating runners
Open water
(a)
Sedge forms a floating mat
that supports other plants
Sedge mat
almost closed
Sediments are deposited
(b)
Original soil
Sediments
(c)
FIGURE 5.17 Diagram of bog succession. Open water (a) is transformed through
formation of a floating mat of sedge and deposition of sediments (b) into wetland forest (c).