Credits

Created by Stephanie Bilodeau, Explore Natural Communities Intern Summer 2017, NatureServe.

Sounds: Battle Sounds, and Cannon Fire, recorded by NPS; Natural Ambiance, recorded by nille (soundbible.com). Public Domain. River Sounds, Indigo Bunting, and Carolina Wren, recorded by ENC Interns 2017. Licensed under Creative Commons: Attribution 4.0.

Photo: Black Walnut Trunk, by Stephanie Bilodeau, courtesy of NatureServe. Licensed under Creative Commons: Attribution 4.0.

References:
Black Walnut
Tour Stop 9 - Burnside Bridge
1862 Battle Map(s) provided by Chris Tawney, NPS
Informational sign on Snavely Ford Trail, NPS

Transcript

Podcast time: 3:42 minutes

[Battle noises and shouting] It was the morning of September 17, 1862. The sound of musket fire filled the air around the Rohrbach Bridge as fewer than 500 Confederate soldiers faced off against the Union corps of more than 12,000 led by General Ambrose Burnside. The Confederates were well dug-in, and after several failed attempts to take the bridge, Burnside sent a division of about 8,000 men led by General Isaac Rodman to cross Antietam Creek south of the bridge here at Snavely's Ford and outflank the Confederate troops.

[Battle noises fading out, water and nature sounds] General Rodman's men waded through the shallow water in the early afternoon, marching up the draw towards the field of battle. What is a draw, you may ask? Well, it's the depression sloping up between those two hills; it’s where the Snavely's Ford Trail runs today. Except that when the Union troops were slogging up the hill in the humid afternoon heat, the hiking trail wasn't here. And since much of the area had been cleared for farmland, neither was most of the forest!

Many of the trees you see here today are black walnut  with dark, thick bark and narrow leaves. The tree tops are pretty open, allowing lots of light to reach the native ground plants and shrubs, like tall, yellow-flowering wingstem  and northern spicebush . This is a prime example of a Successional Black Walnut Forest, which is a transitional plant community common in areas that were once cleared for farmland.

Black walnut seedlings contain a chemical compound called juglone, which is poisonous to some other plants and can stunt their growth or kill them. This bitter-tasting chemical also protects the seedlings by discouraging deer from eating them. All this helps black walnuts outcompete other species and reach full size, dominating the open forest canopy. As these black walnuts die over time, the plant community will change and different tree species will fill in the forest. A more established natural community will eventually emerge that has many different kinds of trees, including some black walnuts. General Rodman's men sure would have appreciated the protective cover of the trees as they prepared to climb the open farmland under enemy fire.

Today, this forest is the site of another, quieter battle as native plants struggle to compete against the exotic plant invaders that are slowly trying to take over the community. Open and sunny, this habitat provides a perfect environment for many non-native invasive species like garlic mustard , Japanese honeysuckle , and stiltgrass . Since most animals in the forest don't typically eat these exotic plants, they are allowed to spread and grow uncontrollably. They eventually shade, crowd, and out-compete native grasses and shrubs, destroying the natural landscape.

You can help reduce threats to native communities by controlling non-native invasive species in your own backyard. Remove exotic invasives before they can spread and always choose native flowers and shrubs for your garden. This will help prevent the expansion of invasive species into natural communities, like the Successional Black Walnut Forest. Doing your part at home can help protect the beauty of the natural communities we all share.

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