The cold, hostile conditions found on mountains have forced plants and
animals to adapt and change they way they find and store food. Organisms in
this environment have to cope with thinner air, lower temperatures, a
shorter growing seasons and infertile soils. These include the Swiss Alps
in Europe the Australian Alps, the Himalyas in East Asia, the Rockies in
North America and Andes in South America. Animals need to keep their body
temperature higher than their surroundings so they need more energy to
survive. The high winds, snow and extreme temperatures mean that food is
hard to find, forcing both plants and animals to find more efficient ways
of gaining energy.
Food webs in alpine regions are simple and fragile compared to food webs
found in other conditions. There are fewer carnivores, herbivores and
primary producers so a delicate balance is needed to allow all organisms to
survive.
Plants in alpine regions need to retain as much available heat from the
environment as possible, this reduces the amount of energy they need to
keep their temperature constant. Their leaves are a deep, dark green as
darker colours absorb and retain more heat. The plants will often be hairy
and lie low to the ground to reduce the amount of heat lost. Many alpine
plants have adapted so that they can grow and even produce flowers at very
low temperatures. The cells are smaller than normal plant cells and contain
high concentrations of solutes which protect the cell from freezing in the
cold conditions, acting like antifreeze in car engines. Some plants can
actually produce enough heat to melt the surrounding snow.
Very few animals are able to live in alpine regions as there is little food
or water available. Water is frozen as snow and few plants grow, those
which do are usually small. Animals need to change the ways in which they
find and use food to survive in these conditions. In winter few animals are
able to find enough food to meet their energy needs so they must migrate,
hibernate or take shelter under or above the snow until summer. Larger
animals such as the bighorn sheep and elk are able to conserve their energy
because of their fat and fur. They usually move down slope during the
colder months where there is more food available and return in spring. The
ground squirrel hibernates over the winter period and adjusts its eating
habits to provide enough energy during this time. During summer it feeds on
nuts and berries in large amounts, providing excess energy which is stored
as fat. It then builds a grass or fur lined burrow and maintains a body
temperature of 8-10 degrees C (46-50 degrees F). Its metabolism drops
dramatically and the stored energy is consumed slowly.
The meadow vole alters its feeding habits, spending its winter under the
snow where it is able to find enough food and water to survive. The rocky
mountain goat has developed a highly efficient digestive system which is
able to extract almost all of the stored energy from plants. During the
winter months it is able to eat fewer plants but still gain the energy it
needs.
Some animals are able to live at high altitudes, forming a small but
efficient food chain. The organisms found to be living at the highest point
is the jumping spider, living at 6 700m (22 000 ft) on Mt Everest. They eat
small flies and springtails, which gain energy from fungi and rotting
vegetation.
