Monday, January 10, 2022

Busy as a Beaver

 by Gary Salathe

The Louisiana Iris Conservation Initiative (LICI), of which I am on the board of directors, has an on-going iris planting project at the Northlake Nature Center near Mandeville, Louisiana. The project started as a Greater New Orleans Iris Society (GNOIS) project in 2017 and LICI picked it up in 2020. Between 2017 and 2020, over 3,000 Louisiana irises were planted by various volunteers.

The Northlake Nature Center was established in 1982 to preserve, study, and publicly exhibit the natural and cultural resources of southeast Louisiana.

The idea was that this site would showcase all five species of the Louisiana iris and educate the public about this native plant, which has been part of the culture of south Louisiana for generations. The Northlake Nature Center’s raised boardwalk provides an ideal safe and accessible way for the public to view Louisiana irises growing and blooming in their native habitat.

The irises were planted in a cypress tree swamp at the nature center. This swamp was created by beavers damming up water drainage that runs naturally through a portion of the property. The beaver dam is ancient. It has 100-year-old cypress trees growing on it. It’s the only reason the cypress swamp is there.

This 2018 photo by photographer John Paul Duet shows some of the blooming irises while the water level in the cypress swamp was at its normal height.

Two years ago, a hole developed in the beaver dam that brought down the water level in the cypress swamp where the irises have been planted. Other competing grasses and bushes took advantage of the newly exposed mud and moved into the iris areas. In the last year, two hurricanes flooded the cypress swamp for extended periods of time and submerged the irises. (The holes in the beaver dam allowed storm surge tides to quickly push water into the cypress swamp.) These combined water level issues have led to the loss of many of the Louisiana irises.

This 2018 photo shows the Louisiana irises that were part of the iris planting project. The irises are in standing water because the water in the cypress swamp is at is normal height. This kept competing weeds, bushes and trees at bay.

Prior to 2020, beavers usually showed up in winter or early spring to repair any holes in their dam and stayed for a couple of months. Once they had eaten all of the available food in the swamp created by their dam they would move on to other ponds in the area.


This photo was taken during the winter of 2018 the day after the beavers repaired their dam for the last time. 

In late 2019, a tree fell across the dam allowing the water in the cypress swamp to drain down. Unfortunately, the beavers did not show up that winter or the spring of 2020 to make repairs. They still haven’t shown up. The beavers are still in the area at other ponds, and it’s likely they have not come back because the number of people visiting the boardwalk spiked during the COVID pandemic. It seems that everyone is trying to find outdoor activities to do and visiting the Northlake Nature Center is one of them. Beavers are very skittish about being around people so it could be a long time, or never, before they come back.


This photo, taken two weeks ago, shows the deepest of the three holes in the beaver dam that have developed since 2019.

This photo from 2020 shows how the grasses and weeds had begun crowding out the irises. They were able to move into the bare mud exposed by the water level staying down in the cypress swamp because of the holes in the beaver dam.

The CEO of the Northlake Nature Center accepted LICI's offer to repair the hole in the dam, which had grown into being three separate holes within a 20-foot section of the dam. We'll consider bringing in more irises to replace the ones killed off after our repairs to the dam stabilize the water level in the cypress swamp and kill back the competing grasses and bushes by flooding them.

The volunteers begin work on Wednesday, January 5, 2022 repairing the beaver dam by digging clay from a nearby natural gas pipeline right-of-way.

The day for the beaver dam repair finally arrived on Wednesday morning January 5, 2022. We organized a volunteer event to get the job done. A group of student volunteers from the University of South Dakota, hosted by a local wetlands restoration non-profit, Common Ground Relief, combined with our volunteers worked hard to repair it. 

Charlotte Clarke, Executive Director of Common Ground Relief, is shown bringing a load of clay to the beaver dam repair site.

Each layer of clay brought in was tamped down using wood timbers. After each layer was compacted, a new 6-inch-deep layer of clay was added.

Most of the crew is shown right after the last wheelbarrow-full of clay was dumped out. 
A job well done!

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