The thought occurred to California biology professor Matt Ritter, “Say, that’s a really big tree.” When he and his students used ropes and harnesses to climb and measure the karri eucalyptus on campus at Cal Poly San Luis Obispo last fall, they confirmed that it’s the biggest of its species on the North American continent.
The 150-foot-tall tree is more than twice as big as the next largest one on the Big Tree Registry of the United States, which recognizes size based on a point system, taking into account canopy width, trunk diameter and other factors. Matt and students Jenn Yost, Chris Wassenberg and Justin Bence also had to do a GPS location of the tree’s latitude and longitude. To calculate the height, they dropped a line from the topmost leaf.
The karri eucalyptus (eucalyptus diversicolor) species is native to southwest Australia. California trees are likely remnants of wood plantation attempts about 100 years ago — unsuccessful because most plantings were of faster growing eucalyptus globulus, which has pulpy wood.
Karri eucalyptus wood, on the other hand, is worthy of fine furniture, Matt said — but no one will be getting their hands on this tree any time soon: the university plans to guard it as a heritage site.
(Karri eucalyptus is available for purchase elsewhere — priced as an exotic because intense logging practices in Australia 50 to 100 years ago reduced the availability).
Trees of this species outside of Australia are mostly removed from natural predators and diseases, so “they’re able to grow pretty much unchecked,” Matt said.
This may explain why the tallest tree on the European continent is also believed to be a karri eucalyptus. (It’s in Spain and is in the process of being measured.)
Keeping an eye out for really big trees, says Matt, “takes the right guy and the right kind of interest.”
For further information, visit http://www.americanforests.org/resources/bigtrees/.