Aspen tree

Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section Populus, of the Populus genus.

These species are called aspens:

The aspens are all native to cold regions with cool summers, in the north of the Northern Hemisphere, extending south at high altitudes in the mountains. They are all medium-sized deciduous trees reaching 15–30 m (49–98 ft) tall. In North America, it is referred to as Quaking Aspen or Trembling Aspen because the leaves "quake" in the wind. This is due to their flattened petioles, allowing the leaves to become more aerodynamic to reduce damage on the tree from severe winds.

Aspen typically grow in environments that are otherwise dominated by conifers--because of this, they have several adaptations that help them survive in their environments. Besides the flattened petioles on the leaves, the broadleaves leaves are deciduous. Since conifers and other evergreens in snowy areas are shaped as such to bear heavy snow loads, aspen trees drop their broadleaves to prevent damage from snowloading. Additionally, the bark is photosynthetic. In the winter when the leaves are dropped, the tree can still photosynthesize through the bark. In the spring and summer months when the leaves are present, they are able to photosynthesize through both. The bark also contains lenticels that serve as pores for gas exchange, similar to how stomata help leaves with gas exchange.

All of the aspens typically grow in large clonal colonies, derived from a single seedling, and spread by means of root suckers; new stems in the colony may appear at up to 30–40 m (98–131 ft) from the parent tree. Each individual tree can live for 40–150 years above ground, but the root system of the colony is long-lived. In some cases, this is for thousands of years, sending up new trunks as the older trunks die off above ground. For this reason, it is considered to be an indicator of ancient woodlands. One such colony in Utah, given the nickname of "Pando", is estimated to be 80,000 years old, making it possibly the oldest living colony of aspens. Some aspen colonies become very large with time, spreading about 1 m (3.3 ft) per year, eventually covering many hectares. They are able to survive forest fires, because the roots are below the heat of the fire, with new sprouts growing after the fire burns out. The high stem turnover rate combined with the clonal growth leads to proliferation in aspen colonies. The high stem turnover regime supports a diverse herbaceous understory.

...
Wikipedia