Finding (and Losing) the Giants

What is a superlative hemlock? We knew from past ENTS surveys that hemlocks were rarely found over 160 feet tall. By taking diameters aloft, we could calculate the wood volume in the tree. This had been done for several hemlocks, and we knew 1,200 cubic feet was a really big hemlock. These trees represented many years of searching by ENTS; thus we selected 160 feet tall and 1,200 cubic feet of wood as “superlative.”

Along with Jess Riddle, an accomplished ENTS tree hunter, we began the project with 22 known hemlocks over 160 feet tall. As field surveys progressed, we began to home in on the particular habitat needed for a superlative hemlock. We found that the ideal habitat not only required old trees but also fell into a discreet elevation range and slope aspect. Although we climbed and measured hemlocks in seven states, the tallest and largest were consistently found in old-growth forests in the near “temperate rainforests” of the southern Appalachians. In fact, all the superlative trees found in the project are within 65 miles of each other in North Carolina, Tennessee, Georgia, and South Carolina.

The lion’s share were found within the Smokies. The park contains nearly 200,000 acres of old-growth forest, 35,000 of which have a significant hemlock component. To date, not a single hemlock located by ENTS outside of the southern Appalachians exceeds 1,000 cubic feet of wood volume or 160 feet tall. In fact, some of the Tsuga Search trees had co-dominant forks that are larger and taller than some state champion hemlocks!

As the project progressed, we sensed there was a “holy grail” to be found in the forests. The number of 160-foot hemlocks soared to near 70 specimens, but none had yet been found to reach 170 feet. Then, one winter day in 2007, Jess discovered it: A slender tree among larger ones managed to hold its head high, and was measured at 171.6 feet from the ground. A climb was immediately arranged to get a more accurate measurement, and the tape confirmed it: 171.7 feet! On this same ridge, two more hemlocks were located and measured at over 170 feet. The second tree climbed reached 172.1 feet. The third, a huge tree we named the Usis Hemlock, soared to 173.1 feet tall, a new world height record!

Usis was later the subject of a documentary film, The Vanishing Hemlock: A Race Against Time, to be released later this year. The extraordinary tree was also featured in a three-dimensional crown-mapping project. Though now dead, Usis has been preserved via a complex 3-D mapping system.

Even at 1,533 cubic feet of wood, Usis was not the largest hemlock discovered. Only four hemlocks have been documented over 1,500 cubic feet. The Caldwell Giant, one of the last discovered, was a six-foot-diameter beast that racked up 1,601 cubic feet of wood. At 393 points, it would have been an unbeatable National Champion had HWA not claimed it first.

These giants were breaking records while on their deathbeds. As the Tsuga Search wound down, we focused our remaining time and resources on detailed study of the 15 tallest and 15 largest trees documented. We took “ecological snapshots” of the forest, compiled a huge database, and submitted the final report to the National Park Service. By 2008, every one of the 75 hemlocks discovered over 160 feet tall was confirmed dead. As for the largest trees, all were dead . . . except one.

The Story of the Cheoah Hemlock