ECOSYSTEMS - THE BASICS

By Griffin Page
Naturalist ~ Eco-guide

Ecology is the science which studies both ecosystems and the biosphere. It focuses on the relationships between living organisms and the habitat in which they live. This science is vast and at times very complex. For the sake of this article, I will keep it simple.

Two different factors come into play in the study of Ecology: abiotic factors which include temperature, altitude, light, availability of certain gases and the types of soil and biotic factors such as populations, communities, symbiosis, parasitism, mutualism etc.

An ecosystem is also composed of 2 parts: the biocene and the biotype. The biocene, also called community, is composed of the living organisms. The biotype is composed of the physical and chemical elements and their characteristics. An ecosystem can be almost microscopic or it can span over great areas. As a matter of fact, there often is a multitude of smaller ecosystems within greater ones. For example, the Amazon forest is considered an ecosystem but so is a swamp inside it. The scale chosen is directly related to the specific area of study.

It is important to understand the relationship between each ecosystems since one affects the other directly or indirectly. Let’s use an example in order to get a clear picture of it’s importance.

Let’s take a small lake or pond. A huge multitude of organisms live inside the pond: fish, bacteria, algae, certain types of insects etc. At the edge of this pond, you’ll find organisms that depend directly upon the pond and the surrounding area. And at the outsides, you’ll find other organisms that depend or not upon the pond and it’s accompanying elements. So, should someone re-route a creak for his convenience and should the pond dry up, all the organisms depending on the pond will be exterminated. All the organisms at the edge of the pond will also be mostly exterminated and many in the surrounding area will have great difficulty surviving or will move to another area. This, without mentioning the non-residing migratory species whom also depend on the pond for rest, food and a source of drinking water while passing through. You can now see, or imagine, the grand scale effect the drying of a single small pond can cause. Now, you can also easily understand the increasing domino effect the destruction of a small habitat or even just one species can have upon it’s surroundings and other species.

There is a common understanding of what a food chain is and how it works. Fortunately, many organisms have a somewhat varied diet. This allows them to adapt to food availability. But there is one very important part of this food chain that most are unaware of. It is almost invisible to the naked eye and without this part, the whole chain collapses. Have you guessed what it is yet? This is how it works:

Producer: Plants, such as grass, need inorganic matter(mineral salts), CO2, light and water in order to photosynthesize and produce energy, some of which is retained and consumed by the next food chain level. (ex: 1% of the energy is retained) *The rest is either expelled through cellular respiration and excrements or simply reflected back into the environment.

Primary: Herbivores, such as rabbits, need plants to feed and in turn produce energy which they retain at a higher percentage than the plants.(May retain 9% but since it comes from the plant, overall you get 0,09%)

Secondary: carnivores, such as foxes, will feed on the rabbits and will retain yet, a even higher percentage of energy than the rabbits.(20% retained from the rabbit but over all it retains 0,018% of the energy originally retained by the producer) *This is why there is never more than 4 or 5 levels in the chain. The total energy retained decreases with each level and becomes insufficient past this limit.

Third: Super predators, such as vultures, will feed on dead, decaying organisms.

But all these produce or leave behind organic matter on which plants are unable to feed. So now, you’ve guessed it. Only bacteria and fungi can transform organic matter into inorganic matter and complete the cycle. So these are in the last category of the food chain: Decomposers

An interesting note can be added to this section: When visiting or trekking in any natural habitat, even though it’s only an apple core, a banana peel or whatever else you just ate and you think it’s ok to throw that into the woods, remember the bacteria part of the food chain. The specific types of bacteria from your apple or banana may not be a species encountered naturally in this area and, since bacteria also compete with each other and some are faster growing, they can be harmful to the ones found in the region. You could be damaging the area in ways you cannot see. The same applies to lakes, rivers and oceans. A simple rule of thumbs to avoid contaminating natural habitats: If it’s not from the area, don’t leave it there.

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