Tierra del Fuego is a truly remote part of the earth, with a unique forestry ecosystem that proves the adaptive ability of trees to survive in the harshest conditions!
by Michal Brink, Forestry Solutions
|Influence of prevailing winds on tree form.||Beaver damage in the forest.|
Tierra del Fuego is the largest island of an archipelago off southern South America separated from the mainland by the Strait of Magellan. The island is divided between Chile and Argentina. South of the island, one finds the Drake Passage connecting the south western part of the Atlantic Ocean with the south eastern part of the Pacific Ocean and extends into the Southern Ocean. The passage is named after the 16th century English privateer Sir Francis Drake.
Drake’s only remaining ship, after having passed through the Strait of Magellan was blown far South in September of 1578. This incident implied an open connection between the Atlantic and Pacific oceans. Earliest human settlement on the island occurred more than 10 000 years ago. The Yaghan people were some of the earliest known humans settling in Tierra del Fuego.
The name Tierra del Fuego (Land of Fire) derives from the Portuguese explorer Ferdinand Magellan sailing for the Spanish Crown, who was the first European to visit these lands in 1520. He believed he was seeing the many fires (fuego in Spanish) of the Yaghan, which were visible from the sea and that the ‘Indians’ were waiting in the forests to ambush his armada.
The climate in this region is very inhospitable. It is a subpolar oceanic climate with short, cool summers and long, wet, moderate winters: the precipitation averages 3 000 mm a year. Temperatures are steady throughout the year: in Ushuaia, the capital, they hardly surpass 9°C in summers and average 0°C in winters. The cold and wet summers help preserve the ancient glaciers and it is not uncommon to have sun, rain and even snow occurring in a single summer’s day. In winter, the mean temperature is between 0°C and 1°C. Winds can reach up to 100 km per hour at times.
Only 30% of the islands have forests, which are classified as subpolar, boreal forests. The northeast is made up by steppe and cool semi- desert. Typical of boreal forests, there are only six tree species found in Tierra del Fuego. The most common of these are the three kinds of Southern Beech; Notofagus antartica, the evergreen Nothofagus betuloides and the most common of all – Nothofagus pumilio (lenga). Pilgerodendron uviferum is one of the lesser known species on the island and is the southernmost conifer in the world.
One of the most amazing features of the beech trees is their capacity to grow under very severe conditions, such as a thin layer of soil that sometimes does not surpass 10 cm thick; steep slopes; an annual mean temperature of 5°C and rainfall varying from 300 to 5 000 mm; wind exposure – winds are so strong that trees in wind-exposed areas grow twisted by the force of winds, and people call the trees ‘flag-trees’ for the shape that they need to take in the fight with the wind. It is truly ‘extreme’ conditions and it is here where this beech tree forest can grow. They provide support for thousands of living things forming this peculiar ecosystem.
From an environmental perspective, the island is struggling to bring an exploding beaver population under control. This invader, introduced from North America, has proliferated from only a few pairs 50 years ago to at least 100 000 today. The Argentinean government imported the original beavers to be raised on commercial fur farms. When the project failed, the beavers were released and quickly spread across the island.
They have since chewed their way through river valleys and stream beds, felling the trees they need for food and building dams, which create even more damage. The population explosion has taken place because the beavers have no natural predators in this new environment.
Published in June 2010