Recipe for a Wetland
by Michael Campbell
Restoring
prairie wetlands can be a difficult task for biologists, who encounter
such challenges as plants that are extraordinarily finicky about where
they grow. Two University of Kansas researchers recently found that
elevation differences as short as the length of a pen can affect the
success of transplanted pieces of prairie sod.
Kelly Kindscher, an associate scientist with the Kansas
Biological Survey at KU, and Alexandra Fraser, a graduate student in
KU's Department of Ecology and Evolutionary Biology, are pioneering
a transplantation technique. In a study published late last year in
the journal Aquatic Botany, Kindscher and Fraser described their effort
to increase the plant diversity at a 17-acre restored prairie wetland
south of Lawrence.
Wetland restoration is of interest to scientists because
of the widespread destruction of these habitats, which filter water,
help control floods and serve as nurseries for many types of wildlife.
Kindscher said that no one knows exactly how many wetlands
have been lost in Kansas, but some estimates put the toll as high as
50 percent. Nationally, seven states have lost at least 80 percent of
their wetlands.
In their study, Kindscher and Fraser transplanted manhole-size
plugs of turf. On some, the grass species spikerush predominated. On
others, eastern cordgrass. Ninety percent of the plugs were still alive
four years after transplanting
The two picked these grasses because neither species
reproduces well by seed and both need transplantation to succeed in
a restoration. All the plugs ended up at virtually the same elevation
because the restoration is in a flat flood plain. If a person stood
on the lowest plug, the highest would be just beneath his knee.
Nonetheless, these subtle variations in elevation were
enough to dramatically affect how the two species fared, Kindscher said.
He attributed the effect to differences in how much the species like
standing water.
Both grasses live in wetlands, but spikerush likes
wetter conditions.
Despite the modest elevation differences in this experiment,
plants at lower elevations spent much more time in standing water than
plants up higher.
As a consequence, the water-loving spikerush flourished
at the lower, wetter elevations but struggled when left high and comparatively
dry.
Cordgrass, on the other hand, preferred the less soggy
high ground. According to Kindscher, these results show how little we
know about restoring natural areas. He said: "It's actually tricky to
figure out what plants to put where. Really, we're pretty crude. For
most restorations, we just scatter seeds and hope things sort themselves
out."
Lots of factors besides water can influence a wetland
restoration's success. Kindscher mentioned shade, the direction a slope
faces and the amount of clay, organic matter and other constituents
in the soil.
To move the transplants, Kindscher and Fraser hit upon
the novel idea of using tree spades, those big truck-mounted claws used
to transport trees.
They believed that the spade's ability to dig deep
holes would improve the transplant's chances for survival.
Previously, people attempting to move prairie plants
cut long strips of turf, a practice used in transplanting sod. Unfortunately,
this technique often damages a plant's roots, which can extend down
four feet or more in wetland species.
"We think tree spades are better because they dig a
little deeper and get more root," Kindscher said. "The transplant success
is very high."
