Ecosystem : a complex system

 

Ecosystem is a complex system composed of the organisms who live in a determinate environment. It consists of  biotic components (PLANTS and ANIMALS) and abiotic components (air, water, light, temperature,…)

Biotic components are divided into:

PRODUCERS (plants, seaweed and some bacteria): they use solar energy to make their nourishment;

COMPOSERS ( for example cow and sheep): they can’t made their nourishment by theirself, so they live on producers;

DECOMPOSERS (mushrooms and bacteria): they live on tissues of dead organisms.

 

Energy transfer in the ecosystem

 

If one of the relations of different components in an ecosystem is damage, total ecosystem will change. The most important relations are those relations compose of energy’s  flows and nutrients’ flows. Ecosystem is open system in respect to the energy, so energy goes in and out from it.  Sun gives energy  and energy goes out like heat, organic matter and organisms produced. Organisms  producers can transformer inorganic compounds in organic compounds trough the photosynthesis. Producers use these compound to live and to grow.

Herbivores eat plants, so they take organic matter and use it to live and to grow. Similarly is the carnivores’ behaviour.

But with “the second thermodynamic principle” there are some losses in the food chain. In fact plants receive more energy than herbivores and herbivores receive more energy than carnivores.

 

Nutrients

 

Organisms to grow and to reproduce need: macronutrients and micronutrients

Macronutrients are carbon, hydrogen, nitrogen, phosphorous and calcium and micronutrients are ferric, magnesium, manganese,…

 

Food chain’s alteration

 

In the lat years new technologies for agriculture’s improvement have needed some pesticides which are dangerous for men and other organisms.

Take DDT for example: when the molecule reaches the sea, it slows down the photosynthetic activity of seaweeds, birds' eggs are frail and break easily during the hatching because they are poor in calcium, decreases the number of individuals population, humans relate to damage organs and systems.

 

Ecosystem is important for man

 

Some ecosystem’s functions are essential to live on earth, so are essential for man. (purification of water and air, climate control, nutrients cycle,…)

Some ecosystems are also too important for economy and tourism.

 

The biome

 

An ecosystem can be big other small. Lakes, greens, seaside, oceans, forests, Earth,… are all example of ecosystem. But extinction of a species, human intervention and other factors can cause their’s change.

Ecosystems which have got similar abiotic components are biomes.

 

Ecosystems on Earth

 

Plant ecosystems are divided into:
• Deserts
• savannah
• steppe
• temperate forests
• tropical
• boreal forest (taiga)
• tundra
• Mediterranean
Aquatic ecosystems are divided in hand:
• freshwater ecosystems: lakes and ponds, rivers and streams, swamps and marshes
• marine ecosystems: coral reefs, oceans, continental shelves, areas of slope of nutrients, estuaries. (See chart)
On Earth, however, there are not only natural ecosystems, but also those created artificially by humans at the same time that development has led him to organize his social life and way of living and produce according to specific characteristics.
The artificial ecosystems are divided into:
• Urban-industrial ecosystems (metropolis)
• ecosystems rural (small towns)
• agroecosystems (cultivated field).

 

The ecological succession

 

The ecological succession is the “story” of an ecosystem. Indeed, during the march of time, pioneers (simple living beings that first managed to live in a particular “inhospitable” environment),change some of the environment’s characters to make it comfortable for more complex living beings.After numerous levels of evolution of these living beings, an ecosystem becomes stable.

A field is different from a natural ecosystem because:

-          farmers delete all the vegetal and animal species that could endanger his plantation.

-          farmers bring energy to the fields with pesticides and machineries

-          harvest (biomass) is taken away from the field, that needs chemical fertilizers and pesticides to produce plants again. Many of these products contain substances like DDT that  very often endanger ecosystems and cause different problems to their species. This is a great problem because unchanged ecosystems are fundamental  for human beings.

 

Ecosystem translation