A prescribed burn on 13 acres of the Lehigh Gap Nature Center has obviously served its purpose. Director Dan Kunkle said statistics prove this point.
The week of July 22 was devoted to monitoring the site where the burn occurred, and comparing it to the nearby sites that were not burned.
He said the new topsoil that has been created by the annual dying and decay of the warm season grasses, which were the first thing planted on the mountain, does not have metals in it. There are microorganisms, bacteria, fungi and invertebrates.
Two things cause concern. The butterfly bush is coming back. It does not provide good food. There is nectar, which is basically sugar-water but the leaves are not suitable to feed the caterpillars an intermediate stage for animals like butterflies.
The gray birch, which is a standard succession plant would be beneficial if it were not for the metals they pull from the ground. When the leaves drop, the new layer of topsoil becomes contaminated. The fire was an attempt to kill both the gray birch and butterfly bush.
Kunkle said they can see the grasses are thriving and there is little difference between the burn area and that which wasn't burned.
The birch has resprouted and it takes a small amount of herbicide to complete the kill. It was easy to see where the butterfly bush resprouted before the grass grew and that was also hit with herbicide. But the grass thriving is not enough to say "proof" so it is being monitored to confirm the observations.
Cornell University set up filters to see what is in the smoke. The U.S. Forest Service set up meteorological towers to determine what was in the smoke and where it blew.
The information will be used to create a computer model to predict if it will reach populated areas and if it would be dangerous to a community.
Kunkle, Scott Showak and Corey Husic will lay out four two- by four-meter plots in the burn area and both upwind and downwind from it to see if the outside areas were affected by the burn. The plots, outlined by joined pipe, are measured across the diagonals. Three transit lines were laid out so comparison can be done with the downwind and upwind plots on an equal line across the burn.
The vegetation is viewed from a yard up (a little less than waist high) and everything is listed from lichens to grass. Wood that burned 60-70 years ago is just listed as wood and is not included in the measurements. Rocks greater than two-inches are counted.
Dr. Tom Whitlow of Cornell worked with Husic on the measurements. He is a restoration ecologist. The day before the work began he called and offered a more accurate method. Fortunately, it is also easier.
"Maybe the grass is doing well but it may have killed other things," said Kunkle. "We are comparing it to the outside for plant diversity."
He points to goldenrod, milkweed and other flowers that are growing.
When the fire was set with the wind behind it, it burned hotter and had a better kill rate. The birches were shading the grasses but now they have caught up to the other grass that was not set back by shade.
The grasses seen this day are grama, big and little bluestem, Canada wild rye, switch grass and Indian grass.
Aspen trees are taking up metals but there are so few they could be easily cut down, Kunkle said.
When the results from the mechanical monitoring are in, a decision can be made about future fires.