The Biggest of the Big

If you're looking for a tree to plant in your zero lot line community, these are not the trees for you! Capable of producing a basal trunk diameter that is larger than some houses, a mature tree from this group would dominate the whole neighborhood, if not the town. As I learned more about these gargantuan specimens, I was struck by the fact that none of them are tropical trees. The fact is that all of the contenders for tallest tree in the world grow in mild, wet environments that occasionally subject the trees to freezing temperatures. Several of these giants of the forest actually grow in temperate rain forests in North America. Another interesting fact is that most of the trees in the "Top Five" are conifers (Gymnosperms), with just one from the Angiosperms, or flowering plants.

The Short List!

The top five contenders are as follows:
  • Coast Redwood (Sequoia sempervirens)
  • Coast Douglas-fir (Pseudotsuga menziesii)
  • Australian Mountain-ash (Eucalyptus regnans)
  • Sitka Spruce (Picea sitchensis)
  • Giant Sequoia (Sequoiadendron giganteum)

The Redwoods and Sequoias are familiar to many Americans and are often put forth as the tallest trees in the world. Indeed, very large specimens of both species are present on the continental United States, and tourists flock to see them every year. However, a study of the historical evidence indicates that Eucalyptus regnans may have, in the past, existed in sizes that even these two forest giants have not reached (see thumbnail picture above, right). Forestry records from Victoria, Australia in 1872 provide evidence that a tree as tall as 500 feet may have existed there. When discovered, the tree had already fallen, but even with a section missing from the top (the broken end still measured 3 feet in diameter!), the tree height was measured at 435 feet (132.6 metres) tall. No Eucalyptus trees near this height are known currently to be alive and growing. The tallest known living tree is currently a Coast Redwood (Sequoia sempervirens) at 379.1 feet.

Coast RedwoodTo get an idea of how large these trees really are, realize that Redwood trees of this size can produce upright shoots from branches high up in the tree. These upright shoots are often taller than a full-grown tree you might have growing in your yard! One particularly amazing picture I've seen shows several of these tree-sized shoots growing on a huge branch 262 feet above the ground. They look like a small grove of trees lined up on the branch! See Redwoods to view the photographs.

These trees form an ecosystem of their own, with many animals and other plants living on them and festooning them. Some smaller trees, shrubs and plants will germinate and grow in pockets high up in these mammoths. Unfortunately, the rush to log has resulted in the destruction of what were probably the largest specimens of each of the top contenders. Even today, pressure to log places these wonders of nature in danger of further destruction. Although many smaller specimens are growing in places around the world, the old-growth giants deserve a special consideration because they are irreplaceable.

Getting (up) high!

Dedicated to increasing knowledge and understanding in the field of tree canopy science are Stephen Stillett and his research collaborators. These intrepid workers have climbed representatives from each of the contenders for tallest tree in search of additional knowledge about tree canopy ecosystems. Their exploits have been written about in several books and national magazines, and the photographs they have to prove what they've done are spectacular and breathtaking.

For an excellent tour of these huge trees by these foremost experts in the field of canopy research, click on Doing Canopy Science.

Image credit: Wikimedia Commons and Public Domain image