Plants and Soils of the Walnut Wetlands

Visitors: Use the links above to learn more about specific aspects of the Walnut Wetlands.

Overview image of the Southeast Swamp.

Southeast Swamp

To the south of Walnut Creek just east of State Street is a large flooded area with many fallen and dead trees. This area can also be recognized looking north from I-40 by the large number of grey-barked standing dead trees.One to two feet of water cover this area throughout the year; this is likely the result of poor engineering during the construction of the beltline in the 1980s. Before the beltline was built this area was part of the Walnut Creek floodplain consisting of vegetation adapted to moist soils without standing water. Many of the plants originally growing on this site were unable to survive with their roots permanently under water like the large willow seen below. The southeast swamp is in an earlier successional stage than the cypress marsh because fewer plants adapted to growing under wet conditions are found on the site. However, the southeast swamp is still very much alive.

Large dead willow (left photo); southeast swamp overview (right).

Evidence of animals in the form of beaver chewed stumps is found throughout the area. A large percentage of the trees have no bark on the bottom 2 feet all the way around the tree. Beaver's girdle trees in this manner to ensure that they will die and fall down so they can use them to build damns and lodges. The photograph of the "animal mound" shows evidence of animal presence because animal foot travel or bird use or nesting has prevented the growth of plants. Animal droppings found in a hole in a tree limb seen below tell us that tree-climbing animals do live in the swamp.

Beaver-chewed stumps (left); beaver-girdled trunks (right).

Animal mound (left); animal droppings (right).

Many plants float on the surface while their roots growth under water . Arrow arum, Peltandra virginica stalks in the late stages of their life cycle are seen poking up through the water and curling over. The arrow arum leaf has a very unique shape and is seen most frequently in the spring and summer. Other plants survive by clinging directly onto other plants; in the photo below a sedge grows directly on the bark of a dead tree.

Water surface (left); arrow arum stalks (right).

Arrow arum leaf (left); sedges on dead tree trunk (right).

Many species of vines such as Greenbrier Smilax rotundifolia avoid the water by hanging out in the trees. Poison Ivy, Toxicodendron radicans, survives in the swamp by climbing up dead trees that are still standing.

Hanging greenbrier (left); poison ivy climbing on tree trunks (right).

Most of the earth mounds that rise above the water surface have plants on them. Here a Silky Dogwood, Cornus amomum, grows on a root mound left by a falling tree. This white flowering flower aster has also found a home on the treefall mound.

Silky dogwood on earth mound (left); white aster on earth mound (right).

A few shrubs are can be found growing directly in the water like this unknown swamp shrub.

<Unknown swamp shrub.

In amazing feats of nature plants can often survive in unexpected ways. This tree is surviving because some its roots are in soil that is above water, allowing some them to transfer carbon dioxide and oxygen. Shoots growing off the main trunk of this tree have started to grow directly towards the sun even after the tree fell down.

Live tree growing from exposed earth mound (left); shoots from fallen tree grow upward (right).

Many plants simply send out a new stem when the old stem dies like this relentless willow sprouting from an old stump.

<Young willow sprout growing from dying stump.