Now that we are aware that the natural environment is under threat mainly because of human-induced actions, we would like to change our behavior towards an environmentally friendly attitude. If we knew enough of how the natural environment functions, we would be in a position to act responsibly because we understand the impact of our actions on it. In the following lessons we would like to instill this understanding by looking at the different components of the environment in Lesson 4 and 5; and then by exploring the functional relationship between these components in Lesson 6 and 7. The best way we are going to make an environmentally sound impact is when we understand what we are fighting for.
According to popular belief, the word ‘ecosystem’ was first used by the British ecologist Arthur Tansley in 1935.
He also identified the term biome as the entire complex of interacting organisms, both plants and animals. He called the physical environment in which the biome exists, the habitat. By the 1950’s these terms have become common concepts. But it must be noted that long before Tansley, people were acutely aware of the close relationship between living and non-living components in the environment.
There is an interconnected functioning from micro-organisms right up to huge predators.
But because the earth is such a huge entity with so many interrelated elements, no one can fully comprehend the intricate relationship that exists. This is why scientists have subdivided the earth into identifiable functionally related units or areas, called ecosystems. Such an ecosystem can be as small and simple as a fishpond or as big and complex as to a tropical forest. Some parts of the earth are very inhospitable such as the Dead Sea, due to its exceptional salinity or the Polar caps where relatively little life is possible due to the cold conditions. But those areas in the biosphere where life thrives are called the ecosphere. Ecosystems that are exceptionally vulnerable due to the human factor, are tropical forests, and coastal ecosystems.
The living or biotic sector of ecosystems consists of plants, animals and humans. The non-living or a-biotic components are light, water, temperature, atmosphere, wind, and soil, the earth’s crust with its associated rock types, topography and landforms, fire and nutrients. The biotic and the abiotic components work together in ecosystems where they actively interact with each other.
As mentioned, the natural world functions as an interconnected system where everything is connected to its surroundings in some way. Nothing exists or functions on its own. As soon as anything is separated from other elements, it stops to function. Therefore, any influence on one element is bound to have a ripple effect throughout the system on all other elements that are directly or indirectly attached to it. You can compare it to a “Tumbling Tower” game where each player in the circle gets a chance to remove a single block from the stack of blocks. At some stage the once stable tower will give in and topple over. Nature has an inherit stability that protects itself against interference from outside. This is called the resilience of an ecosystem. But once this resilience is challenged too far, it will collapse and will not be able to re-establish itself again.
The environment however functions not just as a static collection of blocks, but like an engine with interactive parts.
But what makes this engine “run”? All the activities taking place in and between organic and inorganic components are driven by light or energy that basically comes from the sun. Through the process of photosynthesis, green plants make energy from the sun available to plant-eating organisms like humans, bugs and bigger animals.
Some living organisms are directly dependent on the temperature from the sun for body heat while others, can regulate their own temperature through metabolism and sweat. Some plants and animals have a very low tolerance for temperature change or temperature extremes. The temperatures of the air therefore have a definite influence on the distribution of life on earth. Some plants like apple trees even need a certain intensity of cold temperatures to produce crops.
Many animals such as cold-blooded snakes and lizards, can only function effectively if the environmental temperature is increasing.
The atmosphere and the movement of air or wind plays a crucial role to sustain ecosystems. We cannot breathe if there is no oxygen in the air and plants cannot grow without carbon dioxide in the air. Drops of water in the form of rain cannot be formed without the process of condensation that happens in the air as moisture rises and becomes colder as the altitude increases. Carbon dioxide forms only 0.03% of the atmosphere, oxygen 21%, and nitrogen 78%. In spite of all the processes such as photosynthesis and respiration going on constantly, this composition of the atmosphere remains constant. It is only the amount of water vapor that varies from time to time and from place to place. The wind plays a vital role in moving air around and mixing it so that concentrations stay the same.
Wind moves moisture over oceans towards the continents.
For example, along the coast of KwaZulu-Natal the moisture-laden winds blow over the warm waters of the Indian Ocean and rise over the Drakensberg. As it cools down over the high mountaintops it condensates and come down as heavy rains. Here we can see how landforms with its topography are also an important element in ecosystems. Their orientation also determines the angle at which the sun hits the earth which impacts on vegetation. Vegetation again influences the soil forming processes. Slope elements such as cliffs, valleys and floodplains are all directly the result of interaction between movement in the crust of the earth, rock types and climate over long periods of time.
Far from being a stagnant component of the environment, landforms form part of a dynamic system. Landforms have a direct influence on the soil, vegetation, animal life and human occupation.
The amount of water available determines to a large extent the type and amount of vegetation as well as the amount of associated animal life. Compare for example a marshy area with a desert, or grassland with a tropical forest. In nature the plants and animal life are adapted to the environmental conditions in which it lives.
Fire is also an a-biotic element that plays a crucial role in some ecosystems.
Caused by natural factors such as lightning, it is not necessarily harmful to the stability of an ecosystem as this only happens periodically and at random. Many ecosystems have adapted to seasonal fires such as those that occur in the grassland regions of the world. Fire reduces dead and dry organic matter to soluble compounds and thereby releases elements such as phosphorus, calcium and potassium for rapid recycling, stimulating new growth.
The seeds of some thorn trees are very hard and do not germinate easily. In these cases, exposure to fire helps in the germination process. The fire lily of the Fynbos of the Cape does not flower if there are not periodic veldt fires.
Multiple a-biotic components often interact to achieve certain results. The interactive effects of temperature, wind and rain on rocks are responsible for weathering, by which the element of soil is formed. We have classified soil as one of the a-biotic components of the environment, but this is not really true because soil does not consist only out of weathered rock. Soils hosts the ingredients of air, water, as well as organic material and millions of life-forms, ranging from earth worms to micro-organisms.
A remarkable harmony exists in the functioning of nature. As the ecological dominant, we will remain separate from nature and continue in unsustainable ‘survival practices’ for as long as we do not respect the laws of nature. For example, because our insatiable hunger for progress requires such huge amounts of energy – which is presently not derived directly from the sun, but from limited fossil resources – the environmental crisis could be referred to as an ‘energy’ crisis. Let me explain.
In pre-historic times plant and animal material (latent energy) had been fossilized in the form of coal, oil or gas deposits. Now these energy resources that had been accumulating over millions of years are being utilized rapidly by millions of people all across the globe. Huge amounts of this energy are today used in transport, electricity generation and various industrial processes. However, the byproducts generated when utilizing these energy sources, have many negative impacts on the health of the rest of the environment. The air is being polluted with an overabundance of CO2, methane, lead particles and other harmful gasses which also pollutes soil and water systems. All-in-all, it prevents the proper functioning of ecosystems. We know the negative impact that the usage of fossil fuels has on our life-sustaining environment. There are alternative environmentally-friendly energy alternatives already developed. It is high time to implement them. For as long as we refuse to adjust our pace of development in line with our capacity to generate only clean energy – will we remain on a downward spiral of environmental neglect and self-destruction.
We need to end this article in much the same fashion as previous ones: Because of our behavior many of the building blocks of ecosystems are being destroyed and our very own existence is on the line.
“When the animals come to us,
asking for our help,
will we know what they are saying?
When the plants speak to us
in their delicate language,
will we be able to answer them?
When the planet herself
sings to us in our dreams,
will we be able to wake ourselves, and act?”
— Gary Lawless
The Worldwide Fund for Nature (WWF) has stated that one of the main reasons for the continued environmental deterioration is that people in general fail to recognize the value services that ecosystems provide to the human population.