To find the arid Chihuahuan Desert conditions, a person would have to travel inland to this land-locked region, right? Well, not exactly, at least from the point of view of some plants. All you have to do is go to the top of a tall tree.
Great height, for a tree, presents problems, not the least of which is
getting water to the top. For a mere 100-footer, that's not much of a chore, but
for the towering redwoods, getting water all the way up may be so costly as to stop
growth. Water has to travel from the roots to the top of the tree through small
vessels. In a tree such as the tallest redwood, at 370 feet, the weight of the columns
of water and the friction of the water against the vessel walls increase with height
until the supply of deliverable water is nearly nil. Measurements indicate that between
400 and 426 feet is the theoretical height that a redwood could reach. Feet bathed in
moisture, but barely a drop at the top.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Woodward, I. 2004. Tall storeys. Nature, 428:807-808.