plants in extreme conditions





In many ways, plants are far more versatile and successful to life on earth than animals and have been here for far longer. They were the first to colonise this planet and without them we would not exist, for we are totally dependent on them. Even today with all our technology they continue to amaze us with their ability to inhabit places we humans could not survive, from the frozen Antarctic to the intensity of a volcanic spring, plants utilise their environments to their own advantage and evolve to survive the harshest of landscapes.

A plant needs four basic things to survive, water, warmth, light and minerals and any place that can provide even a little of these essential needs, will be colonised by plants. The most important environmental factors to which plants must adapt themselves to are, water availability, temperature change, light, and soil conditions. For any species, each of these factors has a small or large value, and species that have adapted to extreme environments have undergone changes to adapt to their particular and often narrow ecological conditions. It’s survival of the fittest and the plants that I shall discuss first in this essay, respond to their environment so well that they can live in a part of the world that denies them almost all of their four basic needs, the Antarctic.

The immense Antarctic ice-cap holds three-quarters of the world’s freshwater, this may seem ideal as plants need water, but plants can only use water in liquid form, and the frozen surfaces of the South Pole are inaccessible to them. Light is also a hard commodity to find here as the sun, even in summer never rises high in the sky, and in the autumn it sinks until it leaves the South Pole in darkness for half the year and as for warmth, it is the coldest place on earth. Yet three hundred miles from this place were no living thing could survive for any length of time, there are plants, algae, living together with fungi on the tips of mountains, which protrude through the snow. These hardy plants are mostly in a dormant state, the severe temperatures rising only a couple of days a year just enough to enable the Lichen to enliven their body chemistry and to photosynthesise. Some Lichen is black and this enables them to retain what little of the sun’s heat they can to melt the snow around them. Some grow on rocks that are frequented by birds as their droppings provide a rich source of nutrients. This activity however happens in the warmest part of the summer and as cold winter sets in they return to their dormant sleep.

Other algae manages to survive in the snow itself, they live in between the individual flakes just below the surface and during the summer their chlorophyll is disguised with a red pigment to protect the algae from the ultra-violet rays of the sun, as they shine more strongly through the snow. As the sun shines however, it melts the snow and does give them the liquid water they need. In the winter, when the snow is below zero the algae manufacture a kind of anti-freeze which prevents their bodies from freezing and they are invisible below the surface, but when the summer arrives once more they launch themselves forward with microscopic beating hairs and move closer to the surface and the light.

At the other end of the earth, The North Pole, the situation is different. After the Ice Age, as the ice retreated, plants began to colonise the land it revealed and as they did they evolved in to different forms, better equipped to grow in their new environment. A species of willow developed that grows not vertically but horizontally, restricted to the ground, less the fierce Arctic wind should level it. It may become as long as a European relative would grow high, but it never raises more than four inches of the ground.

In the Arctic summer, the plants that live there have a moderate supply of the four requirements. The temperature is well above freezing, so there is plenty of water around and the sun is high in the sky for weeks. The one thing they are short of however is minerals,