Introduction To Aspen Tree
Aspen is a common name provided to a particular group of trees having beautiful yellow fall color, quaking leaves, and tall grey trunks. These plants are scenic but rare and show flickering foliage in summer. Some, but not all of the tree species included in Aspen have a genus named Populus. Geographically, Aspen trees are distributed to a wide range including North America, Europe, and Asia, depending on the type of species. The Aspen trees are called trembling trees or Quaking trees because the leaves of these trees shake when the wind is blown which is due to their flattened petioles.
The species included in Aspen are the following:
- Populus tremuloides (Quaking Aspen)
- Populus chenopods (Chinese Aspen)
- Populus sieboldii (Japanese Aspen)
- Populus tremula (Eurasian Aspen)
- Populus grandidentata (Bigtooth Aspen)
- Populus davidiana (Korean Aspen)
The Aspen trees are most commonly found in the regions favored by the conifers due to which conifers are their biggest competitors. But due to some unique adaptivity, Aspens have been growing in cold regions with cold summers.
Some of these adaptations are:
- the flattened leaves which decrease the air pressure on the branches
- the strong root system
- lenticels on the bark (as shown in the image below) which helps in gaseous exchange like stomata on the leaves.
- the photosynthetic branches which cause food formation even when the leaves are shed.
- The Aspen trees can grow up to a height of 15 to 30 meters.
- The bark of Aspen trees is grey or greenish-grey. It contains diamond-shaped lenticels on it.
- The leaves of Aspen trees are light weighted having a long stem and flattened petioles which make them move in the wind (quake), measuring between 2.5 and 6 cm across. They contain teeth/blunt ends or edges.
- Aspen trees prefer to grow in a clonal colony, meaning, trees growing together have identical genes. These plants reproduce by vegetative methods only and the individual plant or clone is known as Ramet.
- They contain a Rhizomatic root system.
- Aspen trees can live up to 40 to 150 years above ground but some Aspen trees (for example Pando Aspen) are known to be present on earth for almost 80,000 years. Rhizomatic roots of Aspen trees play a crucial role in the partial immortality of these trees. Individual clones (Ramet) can survive up to 10,000 years or more.
- Aspen is a deciduous and pioneer species that grows very fast.
- The roots of Aspen trees can stay vital for years even after the tree above the ground is dead. The roots lead to the formation of new ramets even in the area where there are no mature parent plants.
Root System Of Aspen Trees
Aspen trees have a sucking and Rhizomatic underground root systems. The roots of these trees help them to survive for thousands of years. The roots of Aspen hold great importance because the shoots of these trees grow from the trunk as well as from the roots. So even after the death of the parent plant, the roots can give rise to Ramets (clone) which do not let the plant die and makes the foliage survive for many years. These roots are invasive and hence are great for preventing soil erosion. The root spreadings of Aspen trees are mainly a tactic used by the plant during unfavourable environmental conditions (scarcity of groundwater). The Aspen trees grown in the gardens or backyard can cause trouble due to their fast-spreading roots by causing damage to the concrete and nearby plant species.
Root System Of Quaking Aspen
Quaking Aspen, scientific name, Populus tremuloides, is a species of the Populus genus. They are commonly called Quaking or trembling Aspen due to the thin stalked leaves of this plant which causes them to shake even with mild breezes. Quaking Aspen is popularly found in North America from Canada to central Mexico. Quaking Aspen is the state tree of Utah state of North America.
The root system of Quaking Aspen is not Rhizomatic but Adventitious. The new shoots arise from the buds of the adventitious root system of these trees. Aspens have shallow roots and they only penetrate the soil up to a distance of 12 inches.
Quaking Aspens have the quality of producing genetically identical offspring from their shoots that arise from their roots. This is done by their ability to multiply asexually which seldom leads to a large swath of land through a shared root system. This ability of the roots of Quaking Aspen to give rise to the Ramets has led to the formation of Pando Aspen which is a single clonal colony of genetically related individuals that arose from a parent male of a single Quaking Aspen.
Root System Of Pando Aspen
Pado Aspen is listed as one of the forty ‘Wonders of America‘. There are multiple reasons for this.
Pando Aspen or ordinarily known as Trembling Giant is an extensive wood of an individual male Quaking Aspen. These are primarily genetically alike trees that are located in the Fremont River Ranger District of the Fishlake National Forest at the western edge of the Colorado Plateau in Utah state of United States. Pando is a single organism living on a single underground root system for many years.
The name Pando comes from the Latin language which means ‘I spread’. The root system of Pando is known to be existing on this earth around 80,000 years ago, which makes it the oldest living organism. It is also the heaviest organism of this earth with a weight of 6,000,000 kilograms (6,600 short tons). It was also once presumed to be the world’s largest organism as it is spread across an area of 107 acres (now usurped by thousand-acre fungal mats in Oregon).
Pando was discovered in 1968 by a researcher Burton V. Barnes and later in 1992, it was named Pando by Michael Grant of the University of Colorado at Boulder.
The roots of Quaking Aspen grow parallel and the root branches arise from the main root. The shoots also emerge from the roots horizontally whenever required. From above the ground, the shoots/branches appear like a new individual when actually it is a stem from the same plant. The shoot grows in size and appears like a new tree which makes it difficult to differentiate between parent tree and shoots. Therefore as explained earlier, even when the parent plant is expired, the root of the Quaking Aspen lives and extend their foliage. This is the case with Pando Aspen but only the roots of this grove have lived long enough and supported the plant from around a million years.
The Pando Aspen is however now a matter of concern because research has noticed that the roots have stopped growing from 40 to 50 years. It has been almost 10,000 years since its last flourishing flowering. The Pando is now dying and human meddling is listed above all the reasons. The grazing of animals near the grove is also killing the new buds which do no let the shoots emerge from the ground. Another reason is the forest fire suppression. Another reason why the Pando survived for so long is the forest fires as the fires although destroy their competitors the underground roots of Pando survived each fire and sent up new stems in the sequel of each wildfire. But due to the suppression of fires, the competitors of the Pando has increased.