Ecosystem & Ecology for Basic Sciences EVS syllabus

Environmental studies include study and knowledge of the various ecosystems and ecology coexisting in our universe starting from the landforms to water bodies to biotics and abiotic components to the very study of pollutants and how to save our environment.

1. Ecosystem & Ecology Presented by: Ms. Merlyn Sylvester

2. What is Ecosystem? Definition: An ecosystem is a structural and functional unit of ecology where the living organisms interact with each other and the surrounding environment. In other words, an ecosystem is a chain of interactions between organisms and their environment. The term “Ecosystem” was first coined by A.G.Tansley , an English botanist, in 1935.

3. Structure of Ecosystem The structure of an ecosystem is characterised by the organisation of both biotic and abiotic components. This includes the distribution of energy in our environment. It also includes the climatic conditions prevailing in that particular environment.  The structure of an ecosystem can be split into two main components, namely:  Biotic Components and Abiotic Components . The biotic and abiotic components are interrelated in an ecosystem. It is an open system where the energy and components can flow throughout the boundaries.

4. Biotic & Abiotic Components Biotic components refer to all living components in an ecosystem.  Based on nutrition, biotic components can be categorised into autotrophs, heterotrophs and saprotrophs (or decomposers). Producers  include all autotrophs such as plants. They are called autotrophs as they can produce food through the process of photosynthesis. Consequently, all other organisms higher up on the food chain rely on producers for food. Consumers  or heterotrophs are organisms that depend on other organisms for food. Consumers are further classified into primary consumers, secondary consumers and tertiary consumers. Primary consumers  are always herbivores as they rely on producers for food. Secondary consumers  depend on primary consumers for energy. They can either be carnivores or omnivores. Tertiary consumers  are organisms that depend on secondary consumers for food.  Tertiary consumers can also be carnivores or omnivores. Quaternary consumers  are present in some food chains. These organisms prey on tertiary consumers for energy. Furthermore, they are usually at the top of a food chain as they have no natural predators.

5. Biotic & Abiotic Components(Cont.) Decomposers  include saprophytes such as fungi and bacteria. They directly thrive on the dead and decaying organic matter.  Decomposers are essential for the ecosystem as they help in recycling nutrients to be reused by plants. Abiotic components are the non-living component of an ecosystem.  It includes air, water, soil, minerals, sunlight, temperature, nutrients, wind, altitude, turbidity, etc. 

6. Types of Ecosystem

7. Types of Ecosystem: Terrestrial Terrestrial ecosystems are exclusively land-based ecosystems. There are different types of terrestrial ecosystems distributed around various geological zones. They are as follows: Forest Ecosystem Grassland Ecosystem Tundra Ecosystem Desert Ecosystem

8. Terrestrial Ecosystem Forest Ecosystem : A forest ecosystem consists of several plants, particularly trees, animals and microorganisms that live in coordination with the abiotic factors of the environment. Forests help in maintaining the temperature of the earth and are the major carbon sink. Grassland Ecosystem : In a grassland ecosystem, the vegetation is dominated by grasses and herbs. Temperate grasslands and tropical or savanna grasslands are examples of grassland ecosystems. Tundra Ecosystem : Tundra ecosystems are devoid of trees and are found in cold climates or where rainfall is scarce. These are covered with snow for most of the year. Tundra type of ecosystem is found in the Arctic or mountain tops. Desert Ecosystem : Deserts are found throughout the world. These are regions with little rainfall and scarce vegetation. The days are hot, and the nights are cold.

9. Types of Ecosystem: Aquatic Ecosystem   Aquatic Ecosystems a re ecosystems present in a body of water. These can be further divided into two types, namely: Freshwater Ecosystem Marine Ecosystem

10. Aquatic Ecosystem Freshwater Ecosystem : The freshwater ecosystem is an aquatic ecosystem that includes lakes, ponds, rivers, streams and wetlands. These have no salt content in contrast with the marine ecosystem. Marine Ecosystem : The marine ecosystem includes seas and oceans. These have a more substantial salt content and greater biodiversity in comparison to the freshwater ecosystem.

11. Natural v/s Artificial Ecosystem Natural ecosystems Artificial ecosystems A biological environment occurring freely in nature rather than being created by man is called as a natural ecosystem Ecosystems that are made by man for commercial or other benefits is known as an artificial ecosystem. These ecosystems are modified by humans for their own profit and can either be terrestrial or aquatic Example: Desert, forest Example: Aquariums, crop fields, dams, gardens

12. Food Chain

13. Food Chain There are basically three different types of food chains in the ecosystem, namely – Grazing food chain (GFC)  – This is the normal food chain that we observe in which plants are the producers and the energy flows from the producers to the herbivores (primary consumers), then to carnivores (secondary consumers) and so on. Saprophytic or Detritus food chain (DFC)  – In this type of food chain, the dead organic matter occupies the lowermost level of the food chain, followed by the decomposers and so on. Parasitic food chain (PFC) –  In this type of food chain, large organisms either the producer or the consumer is exploited and therefore the food passes to the smaller organism.

14. Food Web

15. Food Chain v/s Food Web Difference Between Food Chain And Food Web Food Chain Food Web A linear pathway showing the flow of energy A multitude of networks showing the flow of energy An organism of higher level trophic feeds on a specific organism of lower trophic level An organism of higher trophic level has access to more members of a lower trophic level. Has no effect on the adaptability and competitiveness of organisms. Has a role in improving the adaptability and competitiveness of an organism.

16. Energy Pyramid

17. Energy/Trophic Levels The producers and consumers in the ecosystem can be arranged into different feeding groups and are known as trophic level or the feeding level. The producers (plants) represent the first trophic level. Herbivores (primary consumers) present the second trophic level. Primary carnivores (secondary consumers) represent the third trophic level Top carnivores (tertiary consumers) represent the last level.

18. Energy Flow In ecosystem The chemical energy of food is the main source of energy required by all living organisms. This energy is transmitted to different trophic levels along the food chain. This energy flow is based on two different laws of thermodynamics. First law of thermodynamics, that states that energy can neither be created nor destroyed, it can only change from one form to another. Second law of thermodynamics, that states that as energy is transferred more and more of it is wasted. The energy flow in the ecosystem is one of the major factors that support the survival of such a great number of organisms. For almost all organisms on earth, the primary source of energy is solar energy. It is amusing to find that we receive less than 50 per cent of the sun’s effective radiation on earth. When we say effective radiation, we mean the radiation, which can be used by plants to carry out photosynthesis.

19. Energy Flow Most of the sun’s radiation that falls on the earth is usually reflected back into space by the earth’s atmosphere. This effective radiation is termed as the Photosynthetically Active Radiation (PAR). Overall, we receive about 40 to 50 percent of the energy having Photosynthetically Active Radiation and only around 2-10 percent of it is used by plants for the process of photosynthesis. Thus, this percent of PAR supports the entire world as plants are the producers in the ecosystem and all the other organisms are either directly or indirectly dependent on them for their survival.

20. Energy Fow The energy flow takes place via the food chain and food web. During the process of energy flow in the ecosystem, plants being the producers absorb sunlight with the help of the chloroplasts and a part of it is transformed into chemical energy in the process of photosythesis . This energy is stored in various organic products in the plants and passed on to the primary consumers in the food chain when the herbivores consume (primary consumers) the plants as food. Then conversion of chemical energy stored in plant products into kinetic energy occurs, degradation of energy will occur through its conversion into heat. Then followed by the secondary consumers. When these herbivores are ingested by carnivores of the first order (secondary consumers) further degradation will occur. Finally, when tertiary consumers consume the carnivores, energy will again be degraded. Thus, the energy flow is unidirectional in nature.

21. The 10 Percent Law! According to this law, only 10 percent of energy is transferred from one trophic level to the other; rest is lost into the atmosphere. This is clearly explained in the following figure and is represented as an energy pyramid.

22. Law of Thermodynamics Law of Thermodynamics in the Ecosystem The law of thermodynamics in the ecosystem explains the flow of energy at each trophic level. The first law states that energy is neither created, nor destroyed; it can only be converted from one form to another. This is true in energy flow in the ecosystem. The second law states that there is loss of energy at each step of energy flow. This law also stands true in ecology as their is progressive decrease in energy at each trophic level.

23. Adaptation Adaptation is the physical or behavioural characteristic of an organism that helps an organism to survive better in the surrounding environment.” Living things are adapted to the habitat they live in. This is because they have special features that help them to survive. The development of these special features is the result of evolution due to gene mutation. These mutations aid in survival and reproduction and pass on from one generation to the other. Types of Adaptation: Structural Adaptations : These involve the physical features of an organism that help them to survive in the environment including the different types of terrestrial habitat. The physical changes are related to the changes in the physical environment. For eg. , camouflage, which is the protective colouration that helps an organism to blend in its environment. This protects them from predators and increases their chances of survival.

24. Behavioural Adaptations : This is the change that affects the behaviour of an organism. This could be caused due to the changes in the surrounding environment or due to the actions of other species. For eg : The rabbit freezes if it feels that it has been seen by a predator. Changes in reproductive strategy, feeding habits, migration, hibernation, communication methods are a few other examples of behavioural adaptations. Physiological Adaptations : Like structural adaptations, the physiological adaptations also involve physical changes in the species. However, physiological adaptations are not always seen in the organism’s appearance. This type of adaptation can be either due to changes in the environment or due to the behaviour of other species. For eg : A fish living in water that suddenly becomes more acidic has to shift its body chemistry to adapt itself.

25. Theory of adaptation The theory of adaptation was proposed by Charles Darwin which states that an organism that is able to adapt to the changing environment will survive, the rest will be eliminated. This is known as survival of the fittest. According to the adaptation theory, there are different changes that take place when the habitat changes: Habitat Tracking:  This is when a species finds another similar environment to which it has inhabited before. Extinction:  When the species is unable to find such an environment, it dies or becomes extinct. Genetic Change:  This occurs when organisms with slight genetic changes are better adapted to changed habitat with better access to resources and mating partners.

26. Importance of Adaptation Adaptation is essential for the survival of living organisms. Animals, which are unable to adapt to changing environmental changes die. These adaptations are a result of genetic changes. The animals that survive pass on the mutated genes to their off-springs. This is known as natural selection. Adaptations such as camouflage and colouration protect them from predators. DNA mutations help in the longer survival of animals in dangerous environments and these traits of survival are passed onto future generations. These adaptations make it possible for a variety of creatures to thrive on planet earth. Charles Darwin studied turtles of two islands. The turtles present on one island had short legs, straight shells and derived food present low to the ground. A few turtles migrated to another island, where the food was much higher up. The turtles with longer legs survived. Their necks elongated and shells became rounded over the course of time. Thus, the population on the new island grew with these adaptations in their species.

27. Ecology Ecology is a branch that deals with the interactions between entities and their physical environment. There are different fields of ecology that deals with different subjects. Listed below are the types: Aquatic Ecology : It deals with the study of ecosystems found in water bodies such as estuarine, freshwater and marine. In particular, it deals with the interactions of living entities and a particular aquatic habitat which affects environmental factors such as temperature, predation etc. Microbial Ecology: It studies how microorganisms communicate with their abiotic counterparts and how these interactions are brought about in such organizations. Terrestrial Ecology: It deals with the study of land entities and their interactions with each other to adapt to their immediate surroundings. It is also concerned with diversity and distribution of various entities across the habitat.

28. Taxonomic Ecology: It is a relatively new field that incorporates two branches. It uses taxonomic data to improve ecosystem study by detecting key entities in a particular area. It also helps in the simpler classification of entities at the community level. Systems Ecology: It deals with different abiotic factors such as physical processes(biogeochemical cycle and carbon cycle), allocation of energy budget etc. It integrates computer systems and applied mathematics to predict and study functions in a certain ecosystem. Evolutionary Ecology: It is a field that merges ecology with evolution to study the genetic and physical changes that took place in entities and the repercussions of these alterations in the ecosystem. It involves predation, competition, parasitism, mutualism and other forces of the community. Behavioural Ecology: It combines the study of the interactions between the behaviour of entities and their off-springs and between the survival value of entities which is associated with the evolution process to understand how an entity changes its behaviour to survive and perpetuate.

29. Population Ecology: It is concerned with the study of population structures and associated relationships instead of analyzing behavioural patterns of individuals. It studies factors affecting population size, density, growth and mortality rate etc. Conservation Ecology: It deals with biodiversity management via restoration and conservation methods. Recently it has evolved to approach these issues – a decrease in the biodiversity and destruction of natural resources. Applied Ecology : It aims at applying all the significant information, technical advancements and findings obtained from all concepts and principles of ecology to be able to comprehend real-world situations affecting ecosystems. For instance, epidemiology, wildlife and natural resource management, risk reduction and management due to natural disasters etc. It also incorporates principles of biotechnology to understand its effects on the biosphere.

30. Ecosystem services

31. Functions of Ecosystem The functions of the ecosystem are as follows:  It regulates the essential ecological processes, supports life systems and renders stability. It is also responsible for the cycling of nutrients between biotic and abiotic components. It maintains a balance among the various trophic levels in the ecosystem. It cycles the minerals through the biosphere. The abiotic components help in the synthesis of organic components that involve the exchange of energy.

32. Functions of ecosystem T he functional units of an ecosystem or functional components that work together in an ecosystem are: Productivity –  It refers to the rate of biomass production. Energy flow –  It is the sequential process through which energy flows from one trophic level to another. The energy captured from the sun flows from producers to consumers and then to decomposers and finally back to the environment. Decomposition –  It is the process of breakdown of dead organic material. The top-soil is the major site for decomposition. Nutrient cycling –  In an ecosystem nutrients are consumed and recycled back in various forms for the utilisation by various organisms.

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