Cork oak

Cork oak
Cork oak, showing the dark reddish bark shortly after harvesting (Algarve, Portugal)
Scientific classification
Kingdom:
Plantae
Division:
Magnoliophyta
Class:
Magnoliopsida
Order:
Fagales
Family:
Fagaceae
Genus:
Quercus
Binomial name
Quercus suber

The cork oak (Quercus suber) is a medium-sized, evergreen oak tree. It grows in parts of southwestern Europe and northwestern Africa.

The cork oak can grow up to 20 meters tall, though in its native environment it is usually not that tall. The leaves are 4–7 cm long, darker green above and paler beneath, with the leaf's sides often curved downward. The tree produces acorns that are around 2–3 cm long.

The cork oak tree over time forms a thick, corky bark; after many years, this bark becomes quite thick. The bark is then harvested every 10–12 years as cork. The harvesting of cork does not harm the tree and a new layer of cork regrows, making it a renewable resource.

The cork oak tree is widely cultivated in Spain, Portugal, Algeria, Morocco, France, Italy and Tunisia. Cork oak forests cover approximately 2.5 million hectares in those countries.

Portugal accounts for 50% of the world cork harvest. Cork oaks cannot legally be cut down in Portugal, except for forest management.

Close-up of the characteristically corky bark

Cork oaks live about 150–250 years. Virgin cork (or 'male' cork) is the first cork cut from generally 25-year-old trees. Another 10–12 years is required for the second cork harvest. A tree can generally be harvested a dozen times in its lifetime.[source?] Cork harvesting is done entirely without machinery.

The European cork industry produces 340,000 tonnes of cork a year, with a value of €1.5 billion. The industry employs 30,000 people.

Wine corks represent 15% of cork usage by weight but 66% of revenues.

Cork oaks are sometimes planted as individual trees. The tree is also sometimes cultivated for ornament. Hybrid oak trees of cork oak crossed with turkey oak (Quercus cerris) are common, both in the wild in southwest Europe and in cultivation; the hybrid is known as Lucombe Oak Quercus × hispanica.

Some cork is also produced in eastern Asia from the related Chinese cork oak (Quercus variabilis).

Seed predation

Quercus suber

In many different species of trees seed predation is considered a problem for the continued growth and reproduction of trees, in this case Rabbits are affecting the cork oak tree. During the development of a plant species the seed / acorn stage in development is considered to be the most important yet most vulnerable stage. The cork oak tree encounters many challenges during its seedling stage.

Seeds are often found in the form of acorns that fall to the ground close by to the base of the tree. Those acorns become the beginning development of new trees, which develop over time. However many different species use those acorns as a source of food. When rabbits are living in the same area as the cork oak tree seed regeneration is not affected in a negative way.

An acorn that has partial damage is classified as only having damage to the non-vital parts of the propagule. Therefore, when the acorn embryo is damaged the development of the seed is negatively affected. The affected development causes a difference in shoot and root biomass because the cotyledon is lost. The cotyledon is a necessity of plants and in this case becomes the leaves of the plant. In other cases it helps scientists determine which type of flowering plant it will later develop into. The cotyledons are also an essential source of energy for the development of the seed and plant.

Community interaction

There are two common types of soil that are used in scientific studies, nutrient rich soil and nutrient poor soil. The predation of the seeds is not as important as the nutrient level of the soil. Different plants over time have adapted to grow in these different conditions over time. The acorns of the cork oak tree have better regeneration and development in nutrient rich soil. The smaller cotyledon acorns that grow in nutrient rich soil develop.

References

  1. ↑ =109. In French échelle longue ("long scale") it is called milliard.

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