Depending on the criteria considered, trees are the most massive single organisms on the planet. A blue whale -- the largest animal ever known -- pales in size compared with a North American Douglas-fir, an Australian mountain ash or an African baobab. Most gigantic of all, at least in terms of single-stem trees, is the giant sequoia, which exists in a naturally small dominion in California's Sierra Nevada.
Giant Sequoias in the Sierra
Giant sequoias are found only along the western slope of the Sierra Nevada in California, a range they were probably restricted to at the beginning of the Pleistocene Epoch. They inhabit montane mixed-conifer forests, typically between 1,400 and 2,150 meters (4,590 and 7,050 feet) in elevation. Most sequoia groves are found south of the Kings River, where they are separated from one another by only a few miles. North of the river, a handful of groves are much more widely scattered, ranging to a northernmost outpost, some 25 miles west of Lake Tahoe. The giant sequoias that are largest in terms of trunk volume -- all found south of the Kings -- grow in the Sequoia and Kings Canyon National Parks, Mountain Home State Forest and Giant Sequoia National Monument, part of the Sequoia National Forest, as well as -- in one instance -- private land in that region.
The General Sherman Tree in Sequoia National Park’s Giant Forest Grove has been recognized as the largest sequoia -- and most voluminous tree -- in the world since the 1930s. It boasts a stem volume of some 1,487 cubic meters (52,508 cubic feet). While other sequoias exceed it in basal diameter (the basal area being the cross-section area at a height of 4 1/2 feet) -- for example, the Boole Tree in the Sequoia National Forest’s Converse Basin, which, at 9 meters (29.5 feet) across, is more than 2 feet wider -- the General Sherman outmasses them all by staying remarkably thick high up the trunk. This is the only tree in the world with a trunk diameter surpassing 6 meters (20 feet) at 11 meters (35 feet) off the ground.
Sequoia Rival: The Coast Redwood
California -- as well as a small slice of southwestern Oregon -- also claims the world’s tallest tree, the coast redwood. The loftiest-known coast redwood, Hyperion, looms to 115.61 meters (379 feet) in the back country of Redwood National Park. Groves from the heart of redwood range -- coastal river valleys in the temperate rain forest zone of northwestern California -- constitute the world’s tallest forests and also those with the greatest biomass per acre. While coast redwoods are also the most massive trees in the world after giant sequoias, some evidence actually suggests pre-logging forests of coast redwoods may have contained even bigger trees than the Sierran sequoia groves: The Crannell Giant, a 94-meter-tall (308 feet) redwood felled near Big Lagoon in the 1940s, may have boasted a stem volume of 1,743 cubic meters (61,554 cubic feet), significantly greater than the General Sherman.
The giant sequoia may be the most massive single-stem tree in the world, but other species claim their own superlatives in the size department. The Indian banyan may well have the greatest canopy coverage of any tree: These titanic figs can attain vast spreads of nearly 20,000 square meters (215,278 square feet) by dropping from their branches aerial roots that eventually develop into subsidiary trunks. Quaking aspen, meanwhile, is well-known for sprouting countless clonal stems from single, long-lived root masses, which means such groves could be considered single organisms. By that reckoning, the heftiest “tree” is a huge aspen clone in Utah’s Fishlake National Forest, nicknamed the Trembling Giant or Pando, which weighs in at an astonishing 6,615 tons.