2009-2010 Nahant Marsh Restoration Project

By: Bob Bryant

Wetlands are one of the most complex, diverse and the most difficult ecosystems to manage because you are dealing with water. They are difficult to access, easily disturbed, and management activities are greatly effected by weather conditions. Nahant Marsh Education Center received a restoration grant from River Action, Inc. to aid in the recovery and restoration of the marsh following the floods of 2008.

The rains and floods (including a storm with 80 - 90 mph wind) effected Nahant Marsh both negatively and positively. The negative effects greatly outweighed the positive. The low prairie areas and sedge meadow areas were positively effected by the flood. The sedge meadow areas improved due to increased wet conditions which temporally helped retard the growth of reed canary grass (a highly invasive grass) and cottonwood and allowed an increase in sedge meadow species. At the same time, the flood had minimal effect on the native willows and silver maple in the sedge meadows.

The lowland prairie areas came through the first flood as they normally would following a flood, flowering as expected. However, the second flood was higher, lasted longer and came at the worst time, when many of the plants were developing buds or already blooming. Many prairie species did not tolerate the severe wet conditions. Increased moisture conditions for invasive species such as reed canary grass and phragmites favored their establishment on the normally drier prairie areas.

Both floods scattered debris and trash throughout the low areas of the marsh, especially in the lowland woods and along the north facing slopes overlooking the marsh. Major deposits of cattail debris were deposited along the high water lines after each flood. Depth of cattail debris was as much one foot in some areas, choking out most of the existing ground vegetation. Numerous invasive species such as curly and pale dock, thistles, wild parsnip, dogwoods, sweet clover, mares-tail, giant ragweed, and Queen Anne’s lace increased in areas covered by the cattail debris and silt, or in areas where vegetation had been reduced by the wet conditions. In addition, there was the trash and debris that was deposited by the floods. The severe thunderstorms with high winds toppled or damaged many trees, especially some of the large catalpa trees in the Carp Lake area. Many of center’s trails had downed trees or limbs blocking or hanging over them. Many of trails couldn’t be mowed to the end of the summer.

Two conservation crew leaders and a resource manager were hired for the summer of 2009 through the River Action restoration grant. Six conservation aides were provided by the Iowa@Works Program. A resource manager and three crew members were hired for the summer of 2010, since Iowa @Works Program enrollees were not available.

The greatest threat to the Nahant Marsh’s natural areas and its diversity is invasive species. Because of this, over the two summers, 70-80% of their time was spent on invasive species. Other projects included trail maintenance, beaver management, turtle-nest site restoration, natural area inventories (plants, fish, and dragonflies), cutting up downed trees, picking up trash and junk and water-level management. Rainy day projects included: remounted pegboard in garage, organized office and put up new bookshelves, organized garage, GIS mapping, inventory data entry, installed pumper rails on new boardwalk and cleaned newly acquired taxidermy mounts. A lot of work was accomplished the past two summers and visitors have commented how nice the prairies are looking without as many weeds. Restoration work, especially the control of invasive species, is an necessary ongoing management practice, and we will back at it next summer.