Читать книгу Douglas Fir - Stephen F. Arno - Страница 10

Douglas-fir is an enigma. Its mix of distinctive structural features and physiological attributes produces a tree that is puzzling, exceptional, and in ways a marvel of nature. World class in height, geographic distribution, and wood quality, and unique in architecture and genetic composition, Douglas-fir also acquires nitrogen in novel ways, and at times even irrigates itself. Though this tree has long played an integral role in the lives of humans and animals, many of its secrets are only now being understood through modern science.

Two geographic varieties are recognized, though they exhibit only subtle physical differences. The taller, faster-growing of the two varieties, coastal Douglas-fir (Pseudotsuga menziesii variety menziesii), occupies the Cascades, Sierra Nevada, and the British Columbia Coast Range, and extends westward to the Pacific shore. Regions to the east are inhabited by the typically shorter inland, or Rocky Mountain, Douglas-fir (P. menziesii var. glauca), which grows slower and is more cold-tolerant. There are, of course, exceptions. Some habitats within the coastal distribution—such as bedrock sites in the droughty San Juan Islands—support short, limby coastal Douglas-firs, while inland Douglas-firs in moist, wind-sheltered canyons and ravines often grow straight and very tall with little taper.

Because of its much greater size and hence commercial value, the preponderance of scientific inquiry has focused on the coastal rather than inland variety of Douglas-fir. The descriptions, taxonomic difficulties, potential maximum sizes, and water and nitrogen relationships presented here pertain to coastal Douglas-fir unless otherwise noted.

The tree’s botanical identity confounded science for more than a century after naturalists first described it—even though its wood was already serving as the world’s preferred construction lumber. Douglas-fir was known by more than a dozen common names in the nineteenth century before an official name was finally agreed upon. Selecting a scientific name proved even more elusive. Much drama played out first, and many botanists’ dreams of naming the tree were dashed before an acceptable name was found.

Archibald Menzies, a botanist and surgeon who served as naturalist on an early British voyage to the Pacific Northwest, first collected a specimen of Douglas-fir twigs and needles (but no cones) on Vancouver Island in 1791. Menzies did not describe the tree in his journal at the time because he changed jobs when the ship’s surgeon fell ill, but Meriwether Lewis described Douglas-fir on his return trip up the Columbia River in 1806. Lewis referred to the specimen he collected as Fir No. 5, which included a written description of the foliage and cones and a drawing of the distinctive cone bract.

David Douglas, the botanist whose name would eventually be adopted for the tree’s common name, first arrived in America from Scotland in 1823. The prestige of his association with the Royal Horticultural Society of London opened doors to the finest botanists in the United States, and Douglas made good use of his enhanced access. The timing of his arrival could not have been better. In 1824 the Hudson’s Bay Company announced their plans to sponsor a plant collector along the Columbia River, and the young, welltrained Douglas was the natural choice. As a final step in getting ready for his new job in the Pacific Northwest, Douglas arranged to meet Archibald Menzies in London with high hopes of gathering some last-minute advice. When the two men met in the spring of 1824 for a chat over tea, little could they have imagined the role their names would play in the drawn-out process of selecting both a common and a scientific name for Douglas-fir.

Although still early in his career, the energetic and outgoing Douglas had quickly made a name for himself through his association with the Royal Horticultural Society and Hudson’s Bay Company, and his acquaintance with many big-name botanists of the time. On his first sponsored trip to the Pacific Northwest from 1824 to 1827, Douglas diligently collected specimens and seeds (including 120 pounds of Douglas-fir seed, equivalent to about three million seeds) from hundreds of plants and trees for later study, classification, and planting back home. His plant collection set a record for the number of species introduced by an individual into England, the leading country in botanical research at the time. Upon his return to London in the fall of 1827, Douglas was welcomed home as a celebrity. The prodigious amount of seeds that he sent or carried back to the Horticultural Society in London overwhelmed the capacity of their gardens for planting, requiring them to engage the help of private nurseries. Douglas-fir seedlings resulting from these efforts were widely distributed to public and private gardens across the United Kingdom. Some of the trees remaining from those early plantings now soar more than 200 feet tall; serendipitously, one such giant grows near Douglas’s birthplace in Scone, Scotland.

Given Douglas’s celebrity, it is not surprising that in 1833 the English publication Penny Cyclopaedia used the name “Douglas Fir” in its description of the species, honoring and acknowledging Douglas as the discoverer “of this gigantic species . . . found in immense forests in North-West America.” The Penny Cyclopaedia was a companion publication of the Penny Magazine, a weekly magazine that sold for a penny to make it widely available to the general public. Both publications were put out by the Society for the Diffusion of Useful Knowledge, whose altruistic intent was to educate the working class in Britain. The newly proposed name gained traction in Europe but became just one among many other names used in North America in the 1800s.

In 1909 the US Forest Service officially accepted “Douglas fir” as the agency’s preferred common name for the tree after a census of western lumbermen found that it was used more than all other names combined. But the search for a universally acceptable common name continued. Coastal loggers favored the name “red fir” because of the tree’s reddish heartwood, and many other names were also in use. As late as 1939, Yosemite naturalist James Cole observed, “These magnificent trees from the Northwest are somewhat of a botanical puzzle as indicated by their 28 common names.”

Given the hodgepodge of names for this tree that changed over time and place, difficulty in settling on “Douglas-fir” as the official common name is understandable. It wasn’t until 1950 that the hyphenated version of the name was formally adopted by the Seventh International Botanical Congress in Stockholm. Even today “Douglas fir”—two words—is more often used in the popular media (including in the title of this book) instead of the correct form, “Douglas-fir,” which implies that this distinctive tree is not actually a fir. James Reveal, an expert on the drawn-out process of naming Douglas-fir, found it ironic that the final choice perpetuated a twopart name that is incorrect on both sides of the hyphen. Reveal wryly noted that “This tree is not Douglas’s,” because someone else first described it scientifically, “and it is not a fir,” because the tree’s characteristics—such as hanging rather than upright cones and pointed rather than rounded buds—clearly fall outside the description of true firs.

Finding an acceptable scientific (Latin) name for the genus and species of Douglas-fir was even more challenging. Foliage collected by Menzies on Vancouver Island in 1791, plant collections and descriptions made by Lewis in 1806 along the Columbia, and plant materials collected by Douglas on his trips to the Northwest between 1824 and 1830 provided the basis for eighteen scientific names proposed for this species before a suitable name was found. No other North American conifer even comes close to Douglas-fir in terms of how many names were proposed and rejected before authorities agreed upon a valid name.

The quest began in 1803 when a British botanist named Lambert submitted the first Latin name for Douglas-fir, Pinus taxifolia, based on Menzies’s sample collected in 1791. The submission was rejected because the name had already been assigned to an entirely different conifer. Seventeen additional scientific names would be submitted over the next 150 years, sixteen of which were deemed invalid because the name had either already been used or did not meet international taxonomic rules. During this period, trees were found in the mountains of Southern California, Japan, and remote reaches of China that shared similarly distinctive cones and other physical characteristics with the widely distributed North American tree. In 1867 a French horticulturist named Carrière proposed putting these geographically dispersed but somewhat similar trees into a new genus, Pseudotsuga. By the latter 1800s most taxonomists accepted the new genus name, despite vigorous opposition from a few. One called it “a barbarous combination of the Greek word pseudo = false with the Japanese word tsuga = hemlock.” Another wrote, “One would expect that Pseudotsuga would resemble Tsuga most of all conifers, but Douglas-fir does resemble this genus least of all.” The choice of Pseudotsuga (“false hemlock”) as the new genus name was indeed puzzling, but the buds, needles, and number of chromosomes of this unusual tree kept it from being placed within existing genera such as pine (Pinus), spruce (Picea), or fir (Abies).

Despite acceptance of the genus name Pseudotsuga, attempts to find a suitable species name for this tree remained elusive. Finally, in 1950, Portuguese botanist J. A. F. Franco proposed the currently accepted scientific name for western North America’s common Douglas-fir: Pseudotsuga menziesii (Mirb.) Franco, honoring Archibald Menzies. (The last name, Franco, identifies the person credited with authorship of the scientific name.) It may seem odd that a taxonomist from Portugal would break the impasse in naming an iconic American tree, but his successful effort is less of a fluke than it might seem. Franco was a distinguished European botanist, credited with authoring the name of 193 plant species over his illustrious fifty-six-year career. The newly proposed name avoided duplication of previously used names and was consistent with the international taxonomic framework for naming coniferous trees. Finally, Douglas-fir had acquired officially recognized common and scientific names. For centuries earlier, Salish peoples along the Northwest coast used the terms láyelhp and čebidac, among others, as names to identify these trees.

Douglas-fir’s genetic diversity, which exceeds that of its associates and nearly all other trees worldwide, accounts for some of its outstanding attributes and sets it apart as a singular species. It has thirteen pairs of chromosomes (called diploids) compared to only twelve pairs (or fewer) in virtually all other conifer species in the Northern Hemisphere, including the other species in the genus Pseudotsuga. The physical expression of wide genetic diversity plays out in the tree’s uncanny ability to grow on vastly different sites—varying from six-hundred-year-old dwarfs (inland variety) occupying lava flows in the American Southwest to towering 300-foot-tall giants (coastal variety) anchored in the deep, wellwatered soils of the Pacific Northwest.

Though the coastal and inland varieties of Douglas-fir merge in southern British Columbia, in the western United States an area of semi-arid grassland and sagebrush east of the Cascades separates the two varieties. The coastal variety occupies the coastal mountains and lowlands south past San Francisco to the vicinity of Monterey, the Cascades and Sierra Nevada south to the moist canyons of Yosemite National Park, and the Lake Tahoe area of extreme western Nevada. Curiously, only the coastal variety inhabits California, while the inland form grows in all the western states except California.

Inland Douglas-fir is abundant in central and southern British Columbia but becomes much less common in the harsh, continental climate of Alberta—where it is confined to lower slopes of the Rocky Mountains and grows only as far north as Jasper National Park. In the United States, inland Douglas-fir is abundant in the mountains of eastern Washington, central and eastern Oregon, Idaho, Montana, and southward throughout the Rocky Mountain chain. It also occurs in the high-desert mountain ranges of Arizona, New Mexico, and extreme eastern Nevada, and in increasingly scattered groves all the way to the tropical mountains of southern Mexico, covering a north–south distance of more than 2500 miles—an exceptionally broad range for any American tree. Variation of the inland variety in isolated mountainous areas of Mexico spurred a proposal in 1949 to add four new species to the genus Pseudotsuga. However, genetic work indicates that Douglas-fir migrated southward in Mexico during the Pleistocene Ice Age; isolated populations moved along north–south mountain corridors and occasionally reconnected, but apparently left too little time for any to differentiate into additional species. While the proposal for adding new species was rejected, there is some consensus among taxonomists that the Mexican populations have enough in common, and are sufficiently different from the other two varieties of Douglas-fir, that they deserve recognition as a third variety.

Both coastal and inland varieties of Douglas-fir form tall trees in low and mid-elevation forests within their ranges. For example, coastal Douglas-firs grow from sea level to 3500 feet in northwestern Washington and the inland variety from 7000 to 9000 feet in southern Colorado, New Mexico, and Arizona. Inland Douglas-firs extend upward as shorter trees on south- and west-facing slopes and exposed ridges into the subalpine zone. Sometimes they morph into sheared, shrubby trees in wind-funneling passes along the crest of the Rocky Mountains, and occasionally Douglas-fir takes on the dense, low shrubby form called krummholz above the limit of even stunted, erect trees on high mountain peaks.

Because it adapts to a wide variety of habitats and appears in many forms, no simple description encompasses Douglas-fir. Young trees are the West’s most familiar wild Christmas trees. As they continue to grow, young Douglas-firs produce a broad cone-shaped canopy of upward-projecting limbs with abundant branchlets. When they mature, the trees develop an irregular canopy made up of spreading limbs with drooping branchlets that contrast with the more symmetrical branching habit of their true fir (genus Abies) associates, such as grand fir (A. grandis), white fir (A. concolor), red fir (A. magnifica), and subalpine fir (A. lasiocarpa).

Douglas-fir’s needlelike leaves are about an inch long and attached to all sides of the twigs or branchlets, and unlike those of spruce, they are not stiff or prickly to touch. The cones are very distinctive because of the three-pronged, pitchfork-shaped bracts that project from between the scales.

The cones are green at first but turn tan as they mature and grow up to 2.5 to 4 inches long in the coastal variety and somewhat shorter in the inland variety. They are often abundant, and found hanging among the branchlets or lying on the ground. Sometimes squirrels clip off the dense green cones, the size and shape of a small dill pickle, and then gather them up and cache them in a rotten log or underground burrow in order to have a seed supply as winter food. The brownish mature cones dry out on the tree, their scales flex open, and the papery-winged seeds are dispersed by the wind, sometimes several hundred feet. A sticky pitch may be present on both green and mature cones.

When cones aren’t available for identification, not even old cones on the ground, the tree’s buds are another distinctive feature. They are a rich chestnut-brown color, oval and sharp-pointed, and covered with overlapping papery scales. After the buds burst open in late spring, new light green twigs start to emerge. The bud scales bend backward during this period but remain attached to the previous year’s woody twigs. In contrast, buds of true firs and many other conifers are less conspicuous, blunt, light colored, and covered with wax.

The bark of young Douglas-fir trees is smooth, gray, and spotted with pea-size blisters filled with sticky resin. With age the bark becomes rough, and after a century or longer develops into a dark gray-brown corky substance with deep vertical furrows and no resin blisters. Cutting into the bark of a maturing Douglas-fir with a knife exposes wavy bands of contrasting dark brown and light tan. Mature Douglas-firs, such as one-hundred-year-old “second-growth” that sprang up after historical logging, often have a vertical strip of dried pitch on their bark. The bark is also commonly covered with lichens, some a dull dark color, while others may be bright yellow or a beautiful pastel blue-green. Near the base of big old trees, particularly the coastal variety, bark often thickens to at least 6 inches and protects the tree’s sap-filled growing tissue from lethal heating by fire, which occurs at about 145° Fahrenheit.

One striking attribute of Douglas-fir is exceptional height. Oldgrowth coastal Douglas-firs in sheltered valleys commonly reach 250 feet tall and attain diameters of 5 to 8 feet. Occasionally these monarchs tower 300 feet or slightly higher, putting them among a handful of the tallest tree species in the world, surpassed only by the California coastal redwoods (Sequoia sempervirens), whose record is a tree named Hyperion, measuring 381 feet. Inland Douglas-fir grows more slowly than its coastal kin due to frigid winters and drought-plagued summers exacerbated by daytime relative humidity of 15 percent or less. Still, in narrow valleys and canyons they can attain heights of 150 to 200 feet.

Centuries-old trees are another noteworthy feature of coastal Douglas-fir forests. Trees greater than five hundred years of age are fairly common, and occasionally trees a thousand years and older have been reported for both Douglas-fir and a number of its associates. The oldest coastal Douglas-fir was believed to be a more than 1000-year-old monarch in Lynn Valley in British Columbia. That trees and forests of this species and its associates have survived for centuries may give the impression that they have been a centerpiece of the Pacific Northwest landscape extending back into antiquity. Massive trees, coupled with giant moss-covered logs slowly decaying into the forest floor, seemingly provide visual evidence of sustainable “ancientness.” But tree pollen found in sediment layers underlying small ponds across the coastal Northwest paints a different picture. Today’s Douglas-fir-dominated old-growth forests first appeared in similar form only about six thousand years ago—a mere blip in the calendar of geologic time. Prior to that time, forest vegetation in the Northwest varied greatly depending on rapidly changing temperatures that occurred 10,000 to 6000 years ago.

Douglas-fir’s longevity plays a key role in current efforts to determine climatic patterns (particularly precipitation) over the past centuries and even millennia, providing a baseline for assessing modern-day climate trends. Here it is not the coastal giants but dwarfed, bonsai-shaped inland Douglas-fir trees that have special value.

Growing in the cracks of lava flows at El Malpais National Monument in New Mexico, tiny water-stressed trees survive to amazing ages and their year-to-year growth is highly sensitive to precipitation. Tree rings counted on increment cores show that the oldest known living Douglas-fir at El Malpais dates back 1280 years; another old tree on the flow began life about 960 years ago. These and other centuries-old trees serve as nature’s version of solar-powered data recorders, archiving tree-ring widths through good times and bad. Scientists have used the tree-ring patterns (chronologies) to quantify relationships between ring widths and precipitation over the period for which weather records are available.

After establishing such relationships, scientists use tree-ring patterns to estimate annual precipitation in the more distant past. Ancient (subfossil) logs lying on the barren lava flows provide a record of year-to-year tree growth that extends back even further than the living trees. Tree-ring patterns from relict logs that overlap those of old, living trees have allowed scientists to reconstruct a continuous tree-ring chronology—and thereby estimate precipitation—dating back more than 2100 years. Their work shows a period from 1566 to 1608 to be the driest during the last two millennia. Insights provided by the El Malpais tree-ring data suggest that twentieth-century precipitation trends are not outside long-term norms for that area.

Farther south, the Douglas-firs of central Mexico also produce a sensitive, reliable, and long chronology of climatic history. A stand located about 10 miles northwest of 18,500-foot Pico de Orizaba (Citlaltépetl), southeast of Mexico City, is the largest and the least disturbed by woodcutters and by grazing sheep and goats. Some of the trees are five hundred years old, 100 feet tall, and more than 3 feet in diameter. Their growth-ring patterns have been found to correlate well with regional records of spring rainfall and annual yields of maize, the major food crop. A 528-year climatic chronology developed from Douglas-fir tree rings has been used to estimate annual food production from the pre-Hispanic era to modern times.

This tree-ring chronology was also employed in a study of historic typhus epidemics in central Mexico. Typhus, a deadly disease caused by a bacterium transmitted by body lice, occurs where living conditions are crowded and unsanitary. Mexico has written records of typhus epidemics going back to 1655, and the disease historically accompanies famine and war. Documents describe how drought induced large numbers of subsistence farmers to flee to towns for food relief. There, they lived in densely crowded, squalid camps. Historical records were compared with tree-ring reconstructions of growing-season moisture conditions. Below-average tree growth, indicating drought and poor crop yields, occurred during nineteen of the twenty-two typhus epidemics, the most recent of which began in 1915 during the Mexican Revolution.

Detailed analysis of tree-ring chronologies from Douglas-fir and other trees, notably bristlecone pine (Pinus aristata and P. longaeva), provide a remarkably clear record of climatic variation in many regions of North America. These records are a window to the distant past and are routinely used to accurately date prehistorical events, such as the volcanic explosion that destroyed Mount Mazama and created Crater Lake. They also correlate with ancient records such as the warm climate in Greenland a millennium ago, and centuries later the “Little Ice Age” that devastated European agriculture and resulted in massive famine. Tree-ring records are a living chronology that allows analysis of past and current climatic trends in many areas of the world.

One of coastal Douglas-fir’s secrets to long life and exceptional height is that it doesn’t go it alone. Behind the scenes it gets help from numerous organisms, most of them obscure, and a few even from the animal kingdom. An example that adds further intrigue to Douglas-fir’s story is the role salmon play in linking this tree’s cycle of life and nutritional needs to the sea.

A nitrogen isotope known as 15N, which uniquely identifies it as coming from the sea, provides a stealth source of this nutrient for the coastal Douglas-fir forest and involves a complex biotic web that resembles a relay team. Salmon from the Pacific Ocean travel upstream along the west coast of North America to spawn in the many rivers and streams that drain the coastal uplands. Bears, coyotes, eagles, osprey, ravens, and other raptors and scavengers are drawn to the easy pickings offered by spawning salmon or carcasses of the spawned-out fish. Gorged on salmon and often dragging or carrying dead fish, these animals move widely throughout the forest, leaving fish scraps and their nitrogen-rich urine and scat to fertilize the soil. Trees, shrubs, and understory plants thrive on the enriched soil and further distribute the nitrogen in the form of fallen needles, leaves, and twigs. This novel animal-plant nitrogen web developed over millennia, with most of the animal contribution moving upstream from the ocean to provide the coastal Douglas-fir forest with a component of its annual nutritional needs in the form of marine-sourced nitrogen. Douglas-fir also obtains some nitrogen from terrestrial sources, made available by soil microorganisms that break down woody material. Another source of this nutrient is rainfall, which sometimes contains nitrogen converted from the atmosphere by lightning. Fires and other disturbances also periodically stimulate nitrogen-fixing plants such as red alder (Alnus rubra), Sitka alder (A. sitchensis), buckbrush (Ceanothus), and lupine (Lupinus).

Douglas-fir acquires nitrogen from another kind of biotic partnership, this one with a lichen high up in the tree canopy. Lettuce lichen (Lobaria oregana) is a light green fungus resembling garden lettuce that grows in the crowns of large older trees. Lichens are bizarre organisms typically comprised of two fungi and an alga (photosynthetic cyanobacterium) that allow them to process nitrogen gas from the air, which is otherwise unavailable to plants, and convert it into ammonia nitrogen, a form usable by trees. But the trees cannot acquire this nitrogen directly from the lichens. Instead lichens growing in the canopy must be blown or knocked to the ground by wind or snow, where precipitation gradually leaches nitrogen into the soil as the fungi decompose. This pathway sometimes takes a detour when deer or elk eat the fallen lichens, and the associated nitrogen moves into the soil wherever the animals urinate or defecate. The collective contributions are substantial, as lichens can supply an old-growth Douglas-fir forest with a significant portion of its annual nitrogen needs.

Douglas-fir not only survives but flourishes from associations with other organisms in the forest. Some of these biotic partners are belowground, such as two species of false truffle (Rhizopogon)— fungi that form mutually beneficial relationships exclusively with Douglas-fir. (Approximately two thousand species of fungi have been identified as potential partners with Douglas-fir.) The fungi attach themselves to Douglas-fir’s roots and extract sugars manufactured by the tree to meet their entire energy (food) needs. But the tree also benefits. Fungi that colonize the tree’s roots form an expansive mycorrhizal web, or network, that greatly increases the tree’s ability to access nutrients and water. Early-twenty-firstcentury research has uncovered the sophistication of mycorrhizal networks and how they share characteristics with computer information networks. The network connects Douglas-fir trees of different sizes and ages and allows them to exchange food resources, transfer chemicals needed to fend off insects and disease, and share strategies for tolerating drought. Big trees serve as major connection points in these networks, illustrating their importance in forest structure.

Douglas-fir stumps created by logging sometimes provide visual evidence of belowground networking via root-grafting with surrounding live trees. This phenomenon occurs occasionally in the coastal variety of Douglas-fir and can also be found in moister regions of the inland West. Root-grafting is typically indicated when a layer of pitch-like callus tissue forms on the flat top of the stump. The callus tissue acts as a natural sealant that largely protects the dead stump from decay. Because the stump cannot photosynthesize the food (sugars and starches) it needs for callus formation, it has to obtain them from an external source—live, grafted trees. The trees also benefit, as the stump’s roots are still alive and physiologically active, extracting nutrients and water from the soil and transporting them to the living trees.

If the grafting relationship lasts more than a year, photosynthate (sugars) from the live trees transported back to the stump may be used to grow a new layer (or ring) of wood around the outside of the stump. The dead stump is somewhat analogous to the dead heartwood of a living tree: both serve as the core around which a new ring of live wood is added each year. A half-dozen such root-grafted Douglas-fir stumps have been documented in the Plumas National Forest in Northern California. The stumps vary in size, age, and time since thinning, but the stump that has so far supported the widest layer of post-thinning growth came from a tree that was 120 years old and 33 inches in diameter at the time of cutting. It had grown a 2.3-inch-wide layer (on average) of live wood around the stump in the eighty-seven years since cutting, illustrating the potential magnitude and longevity of this novel networking relationship. Older root-grafted stumps may even grow a rounded mushroom-like cap that is covered with bark, morphing into a bizarre forest inhabitant seemingly more at place in the domain of elves and goblins than in a Douglas-fir forest.

Another intriguing aspect of Douglas-fir relates to a basic life need: water. Besides living in a region that receives copious precipitation, coastal Douglas-fir forests contribute to their own irrigation. The source of this self-generated watering is the fog that forms over the ocean and then drifts inland, enveloping the forest. Here, the huge canopies of Douglas-fir trees harvest moisture through condensation of water droplets on their needles. Given that a single large coastal Douglas-fir supports millions of needles, what may seem like an insignificant “drip-drip” in a hike through the woods turns out to be a significant contributor to the forest’s annual water budget. In the Bull Run Watershed that serves as the water source for Portland, Oregon, fog drip contributes an average 35 inches of moisture, or about one-third of the total annual precipitation.

Scientists continue to delve into the genetic, physiological, and architectural anomalies that make Douglas-fir unique. Increasingly sophisticated measuring instruments and analysis techniques should help shed light on myriad remaining questions and reveal more secrets in the future. The increased knowledge and insights that come from this work, along with the special partnerships Douglas-fir forms with countless other forest organisms, further underscore its status as a world-renowned tree.