How to determine age?
It is not determined out of curiosity. Often this is a necessary procedure in cases where a decision is made to cut down or carry out vaccination procedures.
There are various ways:
- in coniferous trees, whorls (fan-shaped shoots on the trunk) are counted. Years are added to the resulting value: for spruce 7mdash; 3, for fir - 5, for cedar - 10;
- Knowing the average annual growth of a certain type of green space in your area, you need to measure the circumference of the trunk at 1.3 meters from the ground, calculate the diameter and divide it by the growth factor.
A more accurate way is to count the annual rings inside the trunk.
Fruit tree seedlings
The issue of seedling maturation requires separate consideration.
A plant sprouted in summer usually reaches a height of 70-100 cm within a year, the diameter of the trunk at a distance of 10 cm from the roots does not exceed 1-1.3 cm. After a year, the seedling has no lateral branches. Therefore, their removal leaves no traces. No root is longer than 35 cm, and usually no shorter than a quarter of a meter. When the window is not airtight, iftivitis associated with ins.
Particular attention should be paid to seedlings growing in subtropical zones. Under favorable conditions, they can begin to branch in the first year. Unscrupulous sellers may pass them off as an older plant, but as a result, the southern seedling will not survive the winter of the middle zone. You must do this in advance
Tree rings
In places where periodic climate changes occur, trees develop circles in the trunk. The process occurs thanks to the cambium located under the bark. These are living cells that produce growth through division.
In winter the plant sleeps. Life processes in it are inactive. Vigorous activity intensifies in the spring and continues throughout the summer. At this time, the cambium forms many new cells, and the color of summer cells differs significantly from the color of spring cells. As a result, a thin light and wider dark stripe appears inside the trunk.
The dark circles represent growth rings. In some tree species they stand out more clearly, in others they are barely visible. Their thickness depends on the conditions in which the plant was located.
Memory by the tree
Many trees live much longer than people, preserving the secrets of what they have experienced for entire generations. But the most important thing is that they contain a “memory map” of nature, which can be seen by making a cut into a tree trunk. After all, the easiest way to find out about age is to count the tree rings. Today, through the efforts and efforts of scientists, the most popular method of studying age and growth conditions is to take a small sample, called a core, from a tree trunk. The woody plant does not suffer, but continues to develop. Between the wood and the bark is a cellular tissue called the cambium. Tree rings are made up of cambium cells. They divide unevenly, depending on climate and weather conditions, enveloping the wood in a very thin ring, at least one millimeter in size. When dividing, these cells form conducting tissue. Juices and nutrients move along it. This happens in the spring, when frosts recede, the soil thaws and the plant needs nutrition for further growth and development. Closer to cold weather, when the growth process slows down, the walls of the conducting vessels thicken and begin to form denser and stronger annual rings of trees, which subsequently represent the bark of the tree. The bark serves as mechanical protection and gives strength to the trunk.
Determining age by tree rings
You can determine how old a tree is by looking at the circles on the cut at the base of its trunk or on the remaining stump. Ideally, plants form one ring per year. However, natural negative factors can contribute to the appearance of several rings or their absence in one year. If they are not clearly expressed, a solution of aniline, bluing or diluted ink must be applied to the cut.
A less radical way to avoid cutting is to use a Pressler drill.
Its length should approximately correspond to the diameter of the tree. The process does not require cutting:
- hold the instrument at chest level;
- screw it into the trunk to the core;
- We take out the sample and count the number of dark stripes on it.
After the experiment, the tree needs minor therapeutic procedures to cover the drilled hole.
Plants [ edit | edit code ]
The age of the tree is determined by the number of rings on the cut. In exceptional cases, the number of rings may not coincide with the actual age.
Temperate climates lead to easily separable rings, while in the tropics they are indistinguishable [ specify
] .
Each ring consists of two parts.
In the first half of the growing season (spring), more conductive tissue is deposited (thin [2], loose, inside), and in the second (summer and autumn) - mechanical tissue (thick [2], hard, outside).
Tropical plants (for example, dragon tree) do not form growth rings, as they grow all year round.
Ring width [edit | edit code ]
The width of each ring may indirectly indicate the climate of that time.
The following patterns have been established:
wide layers gradually expand from taxon to age, then narrow from origin from ancestors; from seeds - develops narrow layers from fruiting, narrowing of the rings up to 2 times from lighting; in a well-lit tree, the rings are wide on the sunny sides, and in a dense forest they are relatively narrow; for a tree on the outskirts of a forest, you can determine its direction to the forest in the direction of narrow rings from latitude and altitude in the far north or highlands - narrow rings from soils and climate; unfavorable conditions thin the rings
The age of a tree can be determined in several ways, all of them are divided into two groups.
Methods for determining the age of a tree:
- Non-destructive are those that allow you to determine the age of a tree without damaging it or destroying it. This includes counting whorls and measuring the diameter of the trunk.
- Destructive - assume that to determine it is necessary to cut down the tree or disrupt the integrity of the trunk, thereby injuring the plant. This way you can determine the age of a tree by the rings, and also determine the age of the tree by the diameter of the trunk.
The life years of trees in temperate and cold latitudes can be determined by cross-cutting their trunks by counting the growth rings (annual layers). This layer, as a rule, corresponds to the growth of wood during one growing season. The wood that appears in spring and early summer is noticeably different from the later wood that appears in late summer and fall.
When a tree just begins to vegetate, many wide-open vessels form in the wood. In autumn, the vessels form narrow, and the skin itself becomes denser and darker. Usually the transition from early wood to late wood is gradual, but the transition from late to early wood is quite clearly visible, and the boundaries between them are clearly visible to the naked eye. Each ring usually corresponds to one year. Although sometimes so-called false rings occur. This happens if, due to unfavorable summer (drought or cold), it begins to vegetate in the fall.
This is what happened in Türi (Estonia) on August 25, 1818. During a thunderstorm, lightning struck a 25-meter oak tree; the affected tree was cut into pieces. And then it turned out that the concentric layers of oak wood, under the influence of lightning, peeled off from each other and freely extended like a telescopic antenna.
The oldest giant trees
Since the thickness of the trunk increases every year, it would seem that long-livers should be looked for among thick trees. And, indeed, for a long time the giant trees growing in North America were considered the oldest - sequoias and sequoiadendrons.
Sequoias are giant trees: the height is about one hundred meters, the diameter of the trunk reaches 8.5 m. One such sequoia was cut with a seven-meter saw for almost two weeks, and it took 30 railway platforms to transport the wood of this tree. Two more interesting facts. In Sequoia National Park (USA), on the stump of a gigantic sequoia tree, cut down in the middle of the 19th century, enterprising Americans set up a summer dance floor, which simultaneously accommodated 16 pairs of dancers, 20 spectators and 4 musicians.
In Yosemite National Park (20 km from San Francisco), the famous sequoia “wahwonah” grows - a great coniferous tree. In 1881, in place of a huge hollow in its trunk, a tunnel 8.7 m long, 2.5 m wide and 3 m high was made.
The sequoiadendron (Wellingtonia, mammoth tree) has even more impressive dimensions; its trunk diameter reaches 10 m; it grows in California on the western slopes of the Sierra Nevada.
Among these giant trees of the flora, a sequoia was discovered, whose age was 2125 years. For a long time it was considered the oldest tree.
Relatively recently, the palm tree among long-lived trees was lost to the intermountain bristlecone pine, which grows on the rocky slopes of the White Mountains (western North America). No one imagined that, in general, small trees (up to 10 m in height) were of such a respectable age. In 1955, one of these pine trees was cut down for scientific research. When they calculated its age using tree rings, scientists were extremely surprised: bristlecone pine is 4900 years old! The researchers had no choice but to blame themselves for their indiscretion and regret what they had done.
But the rest of the old-time pines were studied with extreme caution and since 1958 they have been taken under state protection. Among the long-lived pines, there were many trees whose age exceeded 4 thousand years. All four-thousander trees received their own names: “Alpha” - the very first discovered tree over 4 thousand years old, “Patriarch” - the thickest tree of the bristlecone pines (trunk diameter 3.5 m), “Methuselah” - the oldest living tree, he is 4600 years old (according to biblical legends, Methuselah lived the longest among people - 969 years).
The annual rings of bristlecone pine are so dense that they are indistinguishable to the naked eye. This is not surprising: after all, over a hundred years, the diameter of the trunk increases by no more than 2.5 cm. And in one of the sections of the cut, only 12 cm long, they counted 1,100 growth rings. So the most ancient bristlecone pines appeared on Earth when the pharaohs began building the first pyramids in Egypt.
Tree rings determine not only the age of a tree
Today, to determine the age of a tree, there is no need to cut it down. Dendrochronologists - specialists in "reading" tree rings - use a gimlet to drill out columns of wood as thick as a lead and then examine them under a microscope.
And Japanese inventors have designed a portable X-ray machine with which you can take pictures of the diameter of the trunk without causing even the slightest harm to the tree; From these photographs, experts determine not only the age of the tree, but also its health (to what extent this word can be applied to the tree).
The width of a tree’s annual rings changes from year to year, so the totality of all the rings is a chronicle in which a connoisseur can read everything: temperature fluctuations in the air, the amount of precipitation, forest fires, the invasion of pests, the death of neighboring trees. The width of each individual ring is also not the same everywhere; it depends on the position of the tree relative to the sun, its shading by neighboring trees, the direction of the winds, and the like.
Is it necessary to decipher the tree record? Of course it is necessary, because it helps to reveal some secrets of the past. For a long time, American historians were worried about the mystery of the rock city built in the 13th century. in Mesa Verde (USA, California). Why did the inhabitants leave it? As the tree rings of the logs, without which, of course, the structures of the ancient city could not do, told, this happened due to many years of drought.
Leonardo da Vinci was the first to propose determining the age of trees by tree rings he also suggested that their width depends on the climate. The connection between the growth of tree rings and meteorological factors - air temperature and precipitation - was first pointed out by Russian scientists A. N. Beketov and F. N. Shvedov in the second half of the 19th century. American researchers from the dendrochronological laboratory of Arizona State University established from the annual layers of bristlecone pine that in the west of North America in 1453, 1601, 1884, 1902, 1941 and 1965. the summer was abnormally cold. Data for 1941 and 1965 coincide with the observations of meteorologists. The fact is that in years with cold summers, the activity of the cambium (the connective tissue that produces wood) is weak. Damage to wood cells formed in summer indicates the invasion of cold air masses.
Thus, by studying the growth rings of bristlecone pines and the preserved fragments of dead wood from these trees, American scientists compiled a consolidated climate calendar of western North America, where up to 6200 BC. e. characterized every year.
Similar studies were conducted in the former Soviet Union. There used to be a dendroclimatochronological laboratory at the Botanical Institute of the Lithuanian Academy of Sciences. It was there that they created a dendroscale covering 900 years. Using the rings of an old cedar discovered in Altai, scientists determined what the climate was like in these places from 1020 to 1979. The dendroscale of the cedar clearly shows how 11-year cycles of solar activity affect the climate. They also noticed 80-90-year rhythms, the cause of which has not yet been fully elucidated.
And in the journal Nature for 1976, a report appeared on a new method for determining the climate of past centuries using tree rings. It has been established that the ratio of isotopes of carbon, oxygen and hydrogen in the earth's atmosphere depends on its temperature. So, by calculating the isotopic composition of each wood ring, it is possible to calculate the average annual temperatures of long ago years. Only for this it is necessary to establish a quantitative relationship between the isotopic composition of annual layers and the known average annual temperature.
Scientists from England, Germany, and the USA worked on the creation of a wood thermometer. They carried out their research in England, where they began recording ambient temperature first - about 300 years ago. Not far from the places where temperatures were recorded, ancient oaks and fir trees were examined and the isotope content in the rings was analyzed. This is how the scale of the wood thermometer was calibrated. The study of old-growth trees helped to find out what the weather was like several centuries ago, when they had no idea that heat and cold could be measured.
But the annual rings of coniferous plants can tell not only about the climate of past centuries. American scientists have found that they also record large volcanic eruptions. After all, during an eruption, a large mass of volcanic ash and dust is released into the upper layers of the atmosphere, which can remain in the atmosphere for two to three years. The smallest solid particles block the sun's rays, so it gets colder on the ground.
By studying bristlecone pines, scientists confirmed the eruption of Mount Etna in 44 BC. e. This is the only eruption recorded in tree rings in 42 BC. BC: it took two years to drive a cloud of volcanic dust and ash from Sicily to America.
The date of the eruption of Etna is well known to scientists, but about another major eruption of the Santorini volcano, which destroyed the Minoan culture on the island. Crete, historians had a dispute. Some believed that the Santorini volcano erupted between 1700 and 1450. n. e., others - between 1500 and 1300. BC e. Based on the growth rings of bristlecone pines, dendrochronologists have determined that the Santorini volcano erupted between 1628 and 1626. BC e.
About ten years ago, the American botanist A. G. Jacoby suggested that by looking at the tree rings of trees growing in areas with seismic activity, one can determine when an earthquake occurred and even how strong it was.
In his reasoning, he is based on the fact that an earthquake usually changes the conditions in which the forest grew: the root system is damaged, the supply of groundwater to the trees changes, and so on. Naturally, these factors affect the growth of the tree and should be recorded in the growth rings. Indeed, earthquakes are marked by dark rings extended on one side.
Soviet scientist N.V. Lovelius suggested that the rings of old-time trees should contain information about supernova explosions in the Galaxy. He studied cuttings of two such trees: juniper (tree-like juniper) and Amur larch. When the annual layers of juniper, discovered high in the mountains of Central Asia, were counted, it became clear that this plant was born in 1163 and lived for 807 years. During this time, three supernova explosions occurred - in 1572, 1604, 1700. and these explosions had an impact on the Earth's biosphere. The supernova explosion slowed down the growth of trees: the inhibition reached its maximum 15-16 years after the explosion; 30 years later, tree growth returned to normal. What physiological processes are disrupted under the influence of a supernova explosion has not yet been established.
By reading the ring history, other information can be gleaned. For example, trees can tell us about the degree of air pollution in different years. American physicists use tree rings to determine the consequences of nuclear tests. Chemists, analyzing the chemical composition of tree rings, study the distribution of trace elements in different periods.
Every time we re-read our favorite book, we find something new in it that we had not noticed before. So it is with the chronicle of annual layers: years will pass and, perhaps, someone will read it in a new way and discover for us a completely different content of this wooden chronicle written by Nature.
V. Petrishin
