Food Webs And Trophic Levels

Energy, water, nitrogen and soil minerals are additional important abiotic components of an ecosystem. The energy that flows through ecosystems is acquired mainly from the sun. It normally enters the system through photosynthesis, a process that as well captures carbon from the atmosphere.

By feeding on plants and on one another, animals play a significant role in the movement of matter and energy through the system.
They as well influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers liberate carbon back to the environment and make easy nutrient cycling by changing nutrients stored in dead biomass back to a form that can be easily used by plants and other microbes.
Ecosystems are restricted both by external and internal factors. External factors like climate, the parent material which forms the soil and topography, determine the entire structure of an ecosystem and the manner things work within it, but are not themselves influenced by the ecosystem.
Other external factors are time and latent biota. Ecosystems are energetic entities—regularly, they are disturbed periodically and are in the course of recovering from a few disturbances in the past.
Ecosystems in related environments that are situated in different parts of the world can possess a few dissimilar characteristics merely because they are made up of various species.
The introduction can lead to significant shifts in ecosystem function. Internal factors not only regulate the processes of ecosystem but are as well restricted by them and are frequently subject to feedback loops.
While the resource inputs are normally regulated by external processes such as the climate and parent material, the accessibility of these resources inside the ecosystem is regulated by interior factors like decomposition, root competition or shading.
Additional internal factors are disturbance, succession and the types of species within the ecosystem. Even though humans exist and function within ecosystems, their collective effects are huge enough to control external factors such as climate.
Biodiversity influences ecosystem function, just like the processes of disturbance and succession.
Ecosystems make available a lot of of goods and services upon which people rely; the principles of ecosystem administration recommend that instead of managing individual species, natural ought to be managed at the level of the ecosystem itself.
Classifying ecosystems into ecologically standardized units is a crucial step towards efficient ecosystem management, but there is no particular, agreed-upon technique to carry this out.
The living organisms that constitute an ecosystem can be separated into three main groups:
Organisms are divided into autotrophs, heterotrophs and decomposers according to their energy pathways. Autotrophs are those organisms that are capable of manufacturing energy-containing organic molecules from inorganic raw material with the help of fundamental energy sources like sunlight.
Plants are the major example of autotrophs, using photosynthesis.
All other organisms ought to make use of food that comes from other organisms in the form of fats, carbohydrates and proteins. These organisms that feed on others are called heterotrophs.
1. Autotrophs are organisms that can manufacture their own food from the substances present in their surroundings with the help of light (photosynthesis) or chemical energy (chemosynthesis). Producers are green plants that make use of sunlight to manufacture food from nutrients obtained from the soil.
2. Heterotrophs are incapable of synthesizing their own food. They depend on other organisms — both plants and animals – for their nutritional requirements. Strictly, the definition implies that autotrophs acquire carbon from inorganic sources such as carbon dioxide (CO2) while heterotrophs obtain their reduced carbon from other organisms.
Autotrophs are normally plants; they are as well known as “self feeders” or “primary producers”. Consumers/heterotrophs cannot produce their own food and ought to obtain it by eating other animals and plants. All animals are consumers.
They are further classified into herbivores, carnivores and omnivores. Herbivores, or plant-eaters, are primary consumers. They are as well source of food for carnivores. Omnivores eat both plant and animal materials.
3. Decomposers: They are mainly bacteria and fungi, which break down the complex substances of dead plants and animals into uncomplicated substances, which are then made accessible once again by producers.
Energy Production in the eco system:
A)Autotrophs manufacture their own energy through one of the following two methods:
1)Photosynthesis – Photoautotrophs make use of energy from sun to convert water from the soil and carbon dioxide from the air into glucose. Glucose makes available energy to plants and is utilized in the production of cellulose which is made use of in the manufacturing of cell walls.
Examples of photoautotrophs are Plants, algae, phytoplankton and some bacteria.
Carnivorous plants like pitcher plant make use of photosynthesis for energy production but rely on other organisms for other nutrients like nitrogen, potassium and phosphorous. Therefore, these plants are in essence autotrophs.
2.Chemosynthesis – Chemoautotrophs make use of energy from chemical reactions to manufacture food. The chemical reactions are normally between hydrogen sulfide/methane with oxygen.
Carbon dioxide is the chief source of carbon for Chemoautotrophs. Example of chemoautotrophs is bacteria found inside active volcano, hydrothermal vents in sea floor and hot water springs.
B)Heterotrophs live by feeding on organic matter manufactured by or accessible in other organisms. There are two types of heterotrophs:
1.Photoheterotroph – These are the type of heterotrophs that make use light for energy but which cannot make use of carbon dioxide as their carbon source. They obtain their carbon from compounds like carbohydrates, fatty acids and alcohol. Examples are purple non-sulfur bacteria, green-non sulfur bacteria and heliobacteria.
2. Chemoheterotroph – These are Heterotrophs that obtain their energy through oxidation of preformed organic compounds, i.e. by eating other organisms either dead or alive. Examples are animals, fungi, bacteria and more or less every pathogen.
Energy cycle
All of the energy of life is made available from oxidation, the burning of sugars, as a countless multiplicities of chemical changes occur before they eventually end up once more as water and carbon dioxide. Plants make use of their own sugars for living and growing, but the huge surpluses they manufacture support the rest of the organic world.
Animals are consumers. They either survive by eating directly from green plants, or indirectly by eating other animals that survive by eating green plants. Animals offer recyclable chemicals back to plants through the process of excretion of their body wastes or when their organic remains decompose back into the soil.
Decomposers break down dead plants and animals and allow their components to be returned to the environment and be reutilized.
Therefore, these non-living parts of the ecosystem are cycled from the surroundings to living organisms and back to the surroundings.
At every step in the food chain, much of the potential energy is given out as heat. This type of energy loss limits the number of steps in the food chain to four or five. Energy, which emanates from the sun and is essential for life, cannot be recycled and is lost as it flows one way through the system.
Processes of Ecosystems
This figure with the plants, zebra, lion, etc shows the two main ideas about the way ecosystems operate: ecosystems possess energy flows and ecosystems cycle materials. These two processes are connected but they are not really the same.
Energy flows and material cycles.
Energy is captured into the biological system in form of light energy, or photons and is transformed into chemical energy in organic molecules by cellular processes which include photosynthesis and respiration, and are finally converted into heat energy.
This energy is dissipated, which means that it is lost to the system as heat; once it is lost it cannot be recycled. Without the constant input of solar energy, biological systems would soon become extinct.
This is why the earth is an open system with respect to energy.
Elements like carbon, nitrogen, or phosphorus enter living organisms in a variety of ways. Plants obtain elements from the surrounding atmosphere, water, or soils.
These nutrients are eaten by animals and during decomposition these materials are not destroyed or lost, but are returned to the environment so the earth is a closed system with regard to elements apart from a meteorite entering the system now and then.
The elements are cycled continually between their biotic and abiotic states within ecosystems. Those elements whose supply is likely to limit biological activity are known as nutrients.

Interaction that exists in an Eco-system

Biotic components and abiotic components of an ecosystem interact with one another and have influence on one another. If the temperature of an area decreases, the life existing there must adapt to it.
Global warming, or the global increase in temperature as a result of the greenhouse effect, will speed up the metabolism rates of the majority of organisms.
Metabolic rate increases with temperature due to the fact that the nutrient molecules in the body are more likely to have contact with as well as react with one another when energized by heat. To adapt to these circumstances, cold-blooded organisms could reside in the shade and not vigorously look for food during daylight hours when the sun is at its brightest.
The carbon and energy integrated into plant tissues (net primary production) is either eaten by animals while the plant is alive, or it remains uneaten when the plant tissue dies and turns into debris. In terrestrial ecosystems, nearly 90% of the NPP are eventually broken down by decomposers.
The remaining is either eaten by animals while still alive and enters the plant-based trophic system, or it is eaten after it has died, and enters the debris-based trophic system. In aquatic systems, the proportion of plant biomass that is being eaten by herbivores is a much higher.
In trophic systems photosynthetic organisms are the primary producers. The organisms that consume their tissues are known as primary consumers or secondary producers—herbivores. Organisms which feed on microbes (bacteria and fungi) are termed microbivores.
Animals that feed on primary consumers are known as secondary consumers- carnivores. Every one of these is referred to as a trophic level.
The sequences of consumption that start from plants to herbivores, to carnivore make up what is known as food chain. In real life situation, the systems are much more complicated than this. In such cases organisms will usually feed on more than one type of food, and may feed at more than one trophic level.
Carnivores may eat a few preys which are part of a plant-based trophic system and others that are part of a debris-based trophic system. A bird for example can feed on both herbivorous grasshoppers and earthworms, which eat debris.
These real life systems, with all the complications make up what is known as food webs instead of food chains.

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