Ronald M. Lanner

Short, but enjoyable, based on the number of interesting things learned. Bristlecone pines (there are three “species”; they hybridize in the lab but apparently not in nature) are fairly important for dendrochronology and climate modeling. The Great Basin species (Pinus longaeva) gets to be about twice as old as the other two (Rocky Mountain Bristlecone Pine and Foxtail Pine); current record age for a living tree is 4810 years; a 4862 year old tree was cut down in 1964. Technically, that’s the number of annual growth rings; bristlecones have been known to skip rings in extremely stressful years. (Author Ronald Lanner notes that some Creationists have claimed that bristlecones must be able to make double growth rings in extremely good years, since all trees were killed in the Flood; he is politely dismissive as the supposed double rings are undocumented).


Dr. Lanner provides a number of explanations for longevity, cautioning with scientific correctness that no particular reason has been proved: the trees grow in marginal environments where there isn’t much competition or predation; individual trees are widely separated and grow on otherwise rocky slopes where there’s little chance of fire spreading to an entire stand; the trees can produce epicormic branches; the trees exhibit sectored growth; and there’s no sign of reproductive senescence. I hadn’t heard of epicormic branches and sectored growth before and they deserve a little more explanation.


“Sectored growth” means each main root serves a sector of the trunk, shaped like a pie slice (although the tree twists as it grows so the sectors spiral); there’s no communication between sectors. Thus if a root dies, the sector associated with it also dies, but the others keep going. Many of the oldest trees have only one or two surviving sectors – there’s a narrow strip of living bark that keeps a sector of wood and associated branches going, while the rest of the tree is dead; this accounts for the rugged appearance of the oldest trees. Because of the spiral growth pattern, there can still be branches on all sides of the tree and the dead sectors don’t form a weak zone on a particular side.


“Epicormic branches” are sort of embryonic branches that stay dormant as the tree grows. They can then begin to grow and emerge right through the side of a mature trunk. Many trees only produce branches from the upper part of the trunk; as the tree grows it gets harder and harder to supply water and nutrients to branches higher up. By making epicormic branches the bristlecones can “grow” anywhere along the trunk.


The lack of reproductive senescence means the oldest bristlecones are still producing seed and pollen at the same rate as a just-matured tree. Most organisms eventually stop reproducing, with a variety of causes – accumulating cellular damage, accumulating mutations in the germ cells, and telomere shortening in the chromosomes – bristlecones show none of these.


Dr. Lanner also has some interesting comments on what exactly it means to be “old”, pointing out that there are clonal-reproducing trees – aspens, huckleberry, creosote bush and Tasmanian King’s holly – where the clonal stand is many times older than the oldest bristlecone; 11700 years for a creosote bush stand in southern California; 13000 years for a huckleberry bush in Pennsylvania; 43600 years for King’s holly, and perhaps a million years for a stand of aspen in Utah. All of these clonal trees and bushes share a common, interconnected root structure – in the case of the King’s holly, all known bushes are connected so there’s only one “individual” in existence. Of course, no individual tree or root or cell in a clonal tree is as old as the clone; however, as Dr. Lanner – presumably a bristlecone partisan - points out, no individual cell in a bristle cone is as old as the entire tree, either. But since bristlecones are not clonal, there’s been an individual tree at a particular spot for 4000+ years, while with a clonal species about all you can see is that there’s a direct genetic connection with something that lived around the same place a long time ago.


There is, of course, the obligatory comment on climate change and the resulting threat to bristlecone pines; while I take the point, there’s no mention that a 4000-year-old bristlecone has already survived climate changes in excess of the worst predicted by the IPCC.


The story of the oldest known tree is rather sad. Normally bristlecone (or any other tree with annual growth rings) age is determined using an “increment borer”, which is basically a narrow steel tube that is screwed into the tree and extracted with a pencil-lead-diameter core. Growth rings in the core can then be counted in the laboratory, and the slim core doesn’t hurt the tree. A University of North Carolina geologist was sampling bristlecones in 1964, but broke his increment borer on the 114th tree, which had extremely dense wood and seemed to be very old – only one sector survived. The Forest Service granted permission to cut down this one tree – probably assuming one bristlecone more or less wouldn’t make that much difference. As it happened, when the trunk slab was taken back to the lab it had 4862 annual rings and was thus the oldest living thing – before it was sawed down. No older tree has been discovered since. Prudently, Dr. Lanner doesn’t mention the location of the current record holders; I had my heart set on some bookshelves.


Lanner does give directions to some bristlecone stands if you want to see them; in Colorado, the Rocky Mountain species, which gets “only” 2000+ years old, grows along the road to Mt. Evans, along Cochetopa Pass, and on a ridge near Fairplay. I’m definitely going to pay some of these a visit. For New Mexicans, you can see Rocky Mountain bristlecones along Forest Road 1950 in Carson National Forest (this is the single largest stand of Rocky Mountain Bristlecones). Most of the Great Basin bristlecone sites require hiking, but there’s some easily accessible in Inyo National Forest – including a visitor center devoted to them – along White Mountain Road north of Big Pine, California. Foxtail pine groves all require hiking, and are all in California (except for a recently discovered stand in the Oregon Klamath Mountains, just north of the state line). Most pictures of bristlecones show ancient, twisted and ravaged looking trees; on casual inspection, an ordinary mature bristlecone doesn’t look that much different from any other pine tree so it might be prudent to study some pictures or get a tree guidebook before going on an expedition.


Recommended; surprisingly exciting for a book about vegetation and I learned a lot about pine botany. Good pictures, good bibliography, and a glossary in case you can’t remember the difference between phloem and xylem.… (més)

On a windswept lip of a mountain just a few miles from our Teasdale, UT property, we have discovered an isolated area with a few gnarled, twisted and beautiful bristlecone pines. Reading this book made me aware that they are thousands-years-old Great Basin bristlecone pines, the oldest living trees and oldest living organisms on earth. Some specimens live over 4,000 years. Their needles can live for forty years. We recognized that the bristlecone area that we found was a 'special place' to be protected and treasured. The author, a retired research forester and biology professor, provided many fascinating facts about bristlecones and explained how these majestic trees live to such a long age, We will return to our off-the-beaten-path bristlecone area time and again and only share the exact place with a few close and trusted friends. Learn much more at the author's website: Ronald Lanner's Tree World http://www.ronaldlanner.com/ In his book, he shares many 'public' locations for viewing bristelcones. Also visit the PBS NOVA website: Mehtuselah Tree http://www.pbs.org/wgbh/nova/methuselah/ (lj)… (més)