The tallest tree in the world, a California redwood, stands 379 feet tall, or slightly taller than a football field is long. Redwoods of the past that have since been cut down probably stood even taller, and may even have reached the theoretical maximum height for trees.
Two opposing forces affect a tree’s possible height. On the one hand, the researchers found, that trees in forests “desire” to grow as tall as possible to overtake neighboring trees and reach stronger sunlight.
On the other hand, gravity makes it more and more difficult to haul water upwards from the roots to the canopy as the tree grows, and leaves thus become smaller near the top.
A team of biologists led by George Koch of Northern Arizona University calculated the theoretical maximum tree height or the point at which opposing forces balance out and a tree stops growing. This point lies somewhere between 400 and 426 feet. When, at a certain height, leaves (or, in the case of redwoods, needles) are not cost-effective — the energy they rein in through photosynthesis doesn’t pay for the energy it costs to bring them water — then the tree stops growing.
As trees grow taller, increasing leaf water stress due to gravity and path length resistance may ultimately limit leaf expansion and photosynthesis for further height growth.the biologists wrote in a 2004 article in the journal Nature
Many factors account for the extreme height of redwoods, including the temperate Northern California climate, nutrient-rich soil, abundant rainfall, fog, and even the tightly-packed redwood forests, which force trees to shoot upward in pursuit of sunlight. These conditions combine to make redwoods not simply the tallest trees in the world, but by Koch’s and his colleagues’ calculations, almost as tall as they could possibly be.