Ecosystem and Energy

Ecosystem

Introduction

An ecosystem consists of the biological community that occurs in some locale, and the physical and chemical factors that make up it non-living or abiotic environment. There are many examples of ecosystems- a pond, a forest, an estuary, a grassland. The boundaries are not fixed in any objective way, although sometimes they seem obvious, as with the shoreline of the small pond. Usually, the boundaries of an ecosystem are the chosen for practical reasons having to do with the goals of the particular study.

The study of the ecosystem mainly consists of the study of certain processes that link the living or biotic components to the non-living or abiotic components. Energy transformation and the biochemical cycling are the main processes that comprise the field of ecosystem ecology.

Components of Ecosystem

Ecosystems are made up of living or biotic components and non-living or abiotic components and these components are important to nearly all types of ecosystems.

1. Abiotic ( non-living) components:It includes non-living chemical and physical parts of the environment , like sunlight, temperature, precipitation, thewater of moisture, inorganic substances (e.g. phosphorous, sulfur, carbon, nitrogen. hydrogen, etc), and organic materials (e.g. carbohydrates, lipids, proteins, etc).
2. Biotic (living) components:Biotic components are living things that shape the ecosystem. Biotic components usually include:

• Producers i.e. autotrophs: e,g, plants, they convert the energy into food through photosynthesis or other sources.
• Consumers i.e. heterotrophs: e.g. animals, they depend on producers for food.
• Decomposers, i.e. detritivores: fungi and bacteria, they breakdown chemicals from producers and consumers ( usually dead) into simpler form which can be reused.

Energy

Introduction

Energy has been defined as the capacity to do work. Energy exists in two forms: potential and kinetic. Potential energy is the energy at rest ( i.e., stored energy) capable of performing work.

Energy flow in Ecosystems

Living organisms can use energy in two forms radiant and fixed energy. Radiant energy is in the form of electromagnetic waves, such as light. Fixed energy is potential chemical energy bound in various organic substances which can be broken down in order to release their energy content.

Organisms that can fix radiant energy utilizing inorganic substances to produce organic molecules are called autotrophs. Organisms that cannot obtain energy from abiotic source but depend on energy-rich organic molecules synthesized by autotrophs are called heterotrophs. Those which obtain energy from living organisms are called consumers and those which obtain energy from dead organisms are called decomposers.

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When the light energy falls on the green surfaces of plants, a part of it is transformed into chemical energy which is stored in various organic products in the plants. When the herbivores consume plants as food and convert chemical energy accumulated in plant products into kinetic energy, degradation of energy will occur through its conversion into heat. When herbivores are consumed by carnivores of the first order (secondary consumers) further degradation will occur. Similarly, when primary carnivores are consumed by top carnivores, again energy will be degraded.

Trophic level

The producers and consumers in anecosystem can be arranged into several feeding groups, each known as trophic level (feeding level). In any ecosystem, producers represent the first trophic level, herbivores present the second trophic level, primary carnivores represent the third trophic level and top carnivores represent the last level.

Food chain

A food chain may be defined as the transfer of energy and nutrients through a succession of organisms through repeated process of eating and being eaten. In a food chain, the initial link is a green plant or producer which produces chemical energy available to consumers. For example, marsh grass is consumed by grasshopper, the grasshopper is consumed by a bird and that bird is consumed by ahawk.

Types of food chains

1. Grazing food chain

The grazing food chain is the food chain in which plants are producers and consumers cycle energy from living plants. In a grazing food chain, only about 10% of energy flows from one trophic level to the other. The rest amount of energy loss in the form of heat during respiration and passed back to the atmosphere.

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2.Detritus food chain

Detritus food chain is the system where the energy produced by abreakdown of dead plants and animals is recycled into agrazing food chain. The detritus food chain cycles energy from non-living remains of both plants and animals (called detritus). Detritus food chain is initiated by microorganisms like bacteria and fungi and other detrivores like fungi, bacteria, and insects.

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Fig. Schematic representation of Detritus food chain

References

Atlas, RM and R Bartha. Microbial Ecology:Fundamentals and Applications. The Benjamin Cummins Publication co. Inc., 1998.

Gordis, L. Epidemiology. third edition. 2004.

Maier, RM, IL Pepper and CP Gerba. Environmental Microbiology. Academic press Elsevier Publication, 2006.

park, K. Park's Text Book of social and prevention Medicine. 18th edition. 2008.