How Old is Old?
How much would you experience if you lived to be 80,000 years old? The year that Rachael and I spent circumnavigating the continent and all that we saw would barely register for an aspen colony in Southern Utah that researchers have nicknamed “Pando”( Populus tremuloides). 80,000 years is the conservative guess on how long these genetically identical clones have been around, some biologists believe it might be closer to a million years old. Pando is considered a single organism because it shares a massive underground root system that propagates by spreading and sending up new trees to the point that this one system now covers roughly 106 acres. It is the genetic continuity that establishes it as possibly the best candidate for oldest living thing. It is also one of the biggest. All that biomass of root and trunks and leaves adds up. Because no individual tree lives more that a couple hundred years it is difficult to be precise in determining Pando’s age. Aspens benefit from the periodic fires common in the Intermountain West, the root system normally surviving burns that can clear the entire forest. The individual trees have been replaced innumerable times while the integrity of the colony has remained intact, new shoots sprouting quickly after each fire. Biologists use clues from its environment and have examined its genetic code to estimate the age. What is certain is that these trees have seen a lot during their time on earth. Ice ages have come and gone. It was many millennia before the first humans wandered into the region and walked under the leafy canopy. Many fantastic mammals flourished then went extinct in Pando’s presence. While traveling through Utah this October we skirted the flank of the Aquarius Plateau, immersed in the golden light of autumn aspen leaves. Each grove changing in unison to create a subtle patchwork of warm hues, a vivid annual show repeated through the ages.
At perhaps 8600 years the “Humongous Fungus” specimen of Armillaria solidipes in Eastern Oregon can’t compete in age with Pando and is arguably less charming. However, covering almost 2400 acres and weighing as much as 35,000 tons it has taken the lead in overall size and mass for a known living organism. Almost none of it is normally visible. The mushrooms that many of us think of as fungus are only the fruiting bodies of much larger life forms. Underground or in the tissues of trees, plants and other organic matter the real life of a fungus takes place in the mycelium and for this species it is spread throughout the soil and wood of a remote section of National Forest. Fungi quietly do a hefty share of the work of ecosystem function. Alongside bacterial cohorts they break down the detritus of any landscape into usable nutrients making lifeless dirt into rich soil. They also form symbiotic partnerships with other organisms, especially plants. Almost all trees and other plants have a specific fungal relationship in the soil that is necessary for them to thrive.
The last quarter of our yearlong exploration brought us back to the western deserts and Eastern California. In the Mojave is another unassuming member of the list of very long living things, the fragrant creosote bush (Larrea tridentata). A single specimen has been dated to 11,700 years old and it is likely that others could be older. This is another life form that persists and garners little attention, a modest plant well adapted to one of our harshest environments. Having a dual set of roots, one deep to find groundwater, the other shallow and spreading to soak up the rare and fleeting rains before they evaporate, this is one of the most dry tolerant plants in North America. This competitive advantage allows creosote to exclude many other plants and it often grows in large evenly spaced patches. Spreading outward, older stems dying out, the plant forms rings that can be roughly aged by diameter, the oldest, like “King Clone” living as irregular 70 foot circles. The record-breaking drought that we may be coming out of is certainly nothing new to this scraggly plant and it has likely seen much worse. In the driest and hottest areas of the continent a sudden downpour can release an oily scent that is evocative to many desert dwellers as synonymous with
rain. Simply plucking a couple waxy leaves and rubbing them between your fingers can conjure thoughts of moisture.
We seem to enjoy pitting creatures against one another in contests over what’s oldest, biggest, tallest, etc. As we look more closely at some of the more obscure places and organisms on our planet we are likely to find older and bigger life forms. These species are of course indifferent to all this but our debate is an interesting one. Where or when does one individual end and another begin. Intuitively we are more comfortable thinking of a living individual as something distinct and continuous over time and clones like aspens and fungus strain our concept of a single entity. I’m perfectly willing entertain these ideas but if I had to pick a favorite participant in our abstract contest I’d have to choose the Bristlecone pine. It once held the throne as oldest living thing and a tree in the White Mountains on the California/Nevada border continues to be considered the oldest individual living specimen.
In November on a cold day accentuated by light snow flurries, Rachael and I joined some old friends to visit these old trees, though the exact spot of the 5065-year-old champion is a closely guarded secret unavailable to us. These are high and windswept mountains that sit in the rain shadow of the slightly taller Sierra crest just to the west. The Great Basin bristlecone pine (Pinus longaeva) found its niche in rugged locations like this and in marginal soils that other species struggle in. It is actually these challenging conditions that produce the oldest trees. In more favorable locations the bristlecones grow well but are eventually out competed by other trees and don’t live nearly as long. The oldest trees also look much different from their coddled counterparts. Weathering droughts and wind and unpredictable conditions for many generations they have adapted by funneling nutrients to the healthy parts and allowing portions of the trunk and branches to die off. The dense and resinous wood maintains its strength and structure for many decades after dying. Any one tree is an intertwined pattern of tough lifeless wood and live tissue twisted into elegant and bizarre forms. When we ask the story of what these old beings have seen in their lifetimes these trees offer us a language we can understand. Examining the annual growth rings in living trees and very old downed wood scientists have built an accurate record of the regional climate for the past 9000 years or more.
Written in lines of wood grain and sculpted into magnificent shapes is the story of countless snowstorms, wind, rain and drought, all the natural forces producing a beautiful and fluent expression.