NAPLES — This was one big tree, a giant even among the giants of Corkscrew Swamp Sanctuary — the massive bald cypress tree's lowest branch was as big as a mature live oak.
Just the kind of tree Mike Knight and Ralph Arwood were looking for.
The two men are in the first phase of an Explorers Club expedition to study giant bald cypress trees at Corkscrew, the largest old-growth bald cypress stand in the world. The sanctuary's average old-growth cypress tree is 11 to 12 feet in circumference; giant trees are 17 to 23 feet.
Knight, regional director of the Explorers Club's Florida Chapter, and volunteer Arwood measured the tree's circumference at 20.2 feet, making it about 700 years old — meaning the tree was growing when Joan of Arc was burned at the stake.
"That's a fun tree," Arwood said. "I like that tree."
Founded in 1904, the Explorers Club is an international society that promotes field research and the exploration of land, sea, air and outer space.
Phase 1 of the Corkscrew expedition is finding, mapping and measuring giant cypress trees in the 800-acre forest. For Phase 2, researchers will climb some of the giants and document every living organism from the canopy to the ground.
"The reason the Explorers Club took interest in this expedition is that you can look ... on Google Earth and see the whole canopy, but you can't see the trees for the forest," Knight said. "It's possible nobody has ever walked through here. There are still blank spots on the map, and here's one of them in our own back yard."
Corkscrew's cypress forest is 5,000 years old, but the oldest trees are 700 years old because a fire burned nearly all of South Florida 700 years ago.
"We want to find how many there are and where they are," Knight said. "We're looking at a snapshot in time, a piece of Old Florida that has existed for centuries."
Finding Corkscrew's giants is not easy.
When surveying an open area such as a coral reef, researchers can simply run transects, a series of straight lines, and count whatever organisms they're interested in. But Corkscrew's cypress forest doesn't have any straight lines; it's a tangled mass of living and dead vegetation.
Instead, Knight and Arwood, using GPS, hiked through the forest looking for giant trees until their path was blocked, then changed directions and walked until their path was blocked again.
In one day, they discovered six giant trees, ranging from 18.2 to 20.2 feet in circumference. To date, the project team with several other volunteers has discovered 49 giant trees. About 200 acres of the sanctuary remain to be explored.
"Out here, you can get the idea of these ancient trees as an integral part of the ecological community," Knight said. "This is the remnant of a once huge, magnificent forest. It's a treasure for us, part of our cultural and ecological heritage."