Geography Reference
In-Depth Information
other continents, and with less than 1% of land surface free of permanent snow and ice,
plant communities are limited in number and scope compared to, say, a hundred million
years ago. Freezing temperatures, modest soil quality, low rainfall, and a general lack of
sunlight for six or more months do not represent ideal growing conditions. But plant and
microbe species exist, nonetheless. It is estimated that there are something like 200 species
of lichen, over 100 species of mosses and liverworts, 30 species of macro-fungi, and a pro-
fusion of algae. The short summer season is key, and even flowering plants are to be found
in the milder Antarctic Peninsula. There is much research on the manner in which these
species became established and indeed survived the harsh and isolated conditions in and
around the polar continent. Given the limited opportunities for photosynthesis and access
to water, some plant life may be hundreds, if not thousands, of years old, with very slow
rates of growth and reproduction.
One of the most remarkable environments within the Antarctic where evidence of life has
been found is the so-called Dry Valleys, which are located on the border between East and
West Antarctica. The three valleys, named Victoria, Wright, and Taylor, encompass some
3,000 square kilometres and are unique in the sense that there is no ice or water to be
found. It was once thought that rain had not fallen for at least two million years, but sci-
entists recorded some precipitation in 1959, 1968, 1970, and 1974. The Dry Valleys were
created when the terrain was uplifted in a manner whereby it actually exceeded the capa-
city of glaciers to cut a path through, and eventually the glaciers simply r a great deal en
Peninsulaeceded. When Robert Scott and his party first encountered them, they observed,
'It is certainly a valley of the dead; even the great glacier which once pushed through it has
withered away.' Latter-day scientists discovered that Scott and his party were a touch pre-
mature, even though it must have been easy to imagine that nothing would survive this vast,
arid, desolate place. In the 1970s, algae, bacteria, and fungi were found to be living inside
the rocks scattered around the Dry Valleys. Some of these plants may date from around
200,000 years ago and survive because the rock protects the organisms from drying while
at the same time enabling some moisture and light to permeate the rocks. Evidence of life
has also been discovered in some of the lakes situated within the Dry Valleys, including
Lake Hoare, where algae is to be found on the bottom of the lake itself. One major concern
for those who study the microbes of the Dry Valleys is human disturbance, as the fragile
rock and soil ecosystems are extremely vulnerable, and further change may occur if alien
species and soils introduced from other continents enter the Antarctic and cross-contamin-
ate.
