Sustaining life on Earth

Have you ever wondered how our Earth is sustaining life by keeping  all its biological (living thing) and non-biological components together. How bonds or interactions are built among both? An ecosystem is the minimal entity that has the properties required to sustain life. Earth is characteristics of ecosystems, not of individual organisms/populations. Life is sustained by interactions and functioning of many organisms together. Ecosystems ( ecological communities along with both biotic and a biotic components) form the baseline. An ecosystem consists of several species i.e

1. Species which produce their own food
2. Species which decompose the wastes of first species
3. A fluid medium between two species.

There are two processes taking place in an ecosystem i.e.

1. A cycling of chemical elements
2. Flow of energy

No individual cell, population or community forms sufficient system to sustain / support life. In the presence of light; green plants algae and photosynthetic bacteria produces sugar and other inorganic compounds from CO2 and water. None of the green plants have the ability to reverse these reactions.

Ecological communities:

A community consists f all the species found in an area whether or not they are known to interact / affect with each other.

                                                               Or 

A set of interacting species found in the same place functioning together to make possible the persistence of life.

Fundamental characteristics of ecological communities:

1. Structure of an ecosystem ( living/biotic and non-living/ a biotic factors)
2. Processes of ecosystem i.e. energy flows and chemical elements cycling
3. Succession ( Series of development which an ecosystem undergoes over time)

Tropic levels:

Tropic levels consist of food web that have same number of  feeding levels away fro original source of energy (sun). Green plants constitute the first tropic level. herbivores are the members of second tropic level, carnivores are third and decomposers on fourth (as they feed on different tropic levels).

 Terrestrial and oceanic food Chains:

Terrestrial and oceanic food chains are almost the same expect for the act that oceanic food chains have more tropic levels.

The community effect:

A species can affect other species (indirectly) by influencing members of that community. It has effects on environment which in turn, may affect group of species in a community. These indirect but complicated interactions are referred to as community level interactions i.e. interactions between two species which lead to changes in presence/absence of other species.

The holistic view of the Community:

If every single species  are considered to be essential to the organization/ community, it would be viewed as super-organism whose components species could not be easily replaced buy others.Species associations are not constant rather they vary from site to site and they also change over time. Every additional species in a community adds more species interactions (predator-prey/ symbiosis).

Identification of an ecosystem:

Te term ecosystem is applied to areas of the Earth that differ greatly in size (ranging from puddles to forests) and composition ( species in a small place to hot springs)however they differ in the kinds/relative proportions of their non-biological constituents in their degree of variations in time/ space. Some ecosystems have defined borders (like a lake and the surrounding countryside) while others have vague borders (like from boreal forests to tundra in far north). Transitions are also observed in areas (like conversion of a desert to forest e.g San Francisco Mountains in Arizona. Ecosystems can be natural/ artificial or a combination of both. They can be managed by applying large number of actions.

Ecosystems are real and important but it is difficult to determine their limits. Moreover the creation of an artificial ecosystem requires an understanding of many complex interactions . Being the keystone species, human have the power/ benefit to control the environment as his effects are direct and create great differences by their actions on the environment. Therefore there is a great need of reviewing the consequences of human impact on environment. This is the only way which can lead us to the reduction in harmful impacts on environment.

Reference: Botkin & keller., Ecosystems and Ecological Communities.,Environmental Sciences, Edition 1