The Ecosystem: Interrelationships between organisms and the environment

1. The Ecosystem: Interrelationships between organisms and the environment 1. Should we care about the survival of organisms other than human beings? 2. Can we humans live alone and survive on the planet? 3. Does the way nature operates offer solutions to our environmental problems?

2. Definition of Terms �1 Ecology: A study of the interrelationships between living organisms and the non-living components and processes that make up the global environment. Biosphere: The worldwide system within which all life functions. It includes the atmosphere (air), hydrosphere (water) and the lithosphere (soils, rocks) Biome: A major ecological region within which plant and animal species are similar in general characteristics and in their relationships to the physical environment. E.g.. Tundra, Deserts, Forests Grasslands etc.

3. Definition of terms�2 Ecosystem: A collection of living organisms in a geographic area, together with the non-living things with which they interact. Aquatic Ecosystems (water-based systems) Terrestrial Ecosystems (land-based systems). Population: A group of organisms of the same kind living in a given area. Natural Community: Populations of different species living together and interacting in a given area. Habitat: The environment in which a particular organism lives in the community

4. Definitions�3 Ecological Niche: An organism�s role within a community. Environment: Comprises all the surrounding things that affect an organism or a community of organisms in a given area.

5. The Structure of Ecosystems�1 Components of an Ecosystem: Biota or Biotic component: the living organisms comprising all plants & animals Abiotic component: the non-living physical and chemical components consisting of wind, temperature, water, soil, precipitation which the biotic elements need to survive.

6. Structure of an Ecosystem�2 A single abiotic factor most lacking in a particular environment is termed, a Limiting Factor. E.g. water-desert, temperature-tundra The variation in physical factors that an organism can withstand and continue to thrive in an environment is termed - Range of Tolerance

7. Producers in an Ecosystem Categories of Organism in an ecosystem Autotrophs � self-nourished species (e.g. plants) Heterotrophs � other-nourished species (humans and animals) 1. Producers: Green Plants responsible for photosynthesis and the release of energy into an ecosystem.

8. Consumers and Decomposers 2. Consumers a) Primary Consumers - Herbivores b) Secondary Consumers � Carnivores c) Tertiary Consumers - Carnivores d) Multiple-level Consumers - Omnivores 3. a) Detritivores �e.g. crab, vulture, termites b) Decomposers � e.g. fungi and bacteria

9. The Food Chain A food chain or food web is represented by a sequence of organisms through which energy and nutrients flow from one organism to another. A major step in the transfer of energy through the food chain is termed as a Trophic level Primary consumers � First trophic level Secondary consumers - Second trophic level Tertiary Consumers - Third trophic level The amount of usable energy in the food chain decreases as we move down the trophic level

10. An example of a marine food chain Phytoplankton is the first level of marine food chain Zooplanktons are eaten by krill and other Small fish which are all eaten in turn by Big fish, including penguins, seals and whales. The marine food chain continues when these big fishes are eaten by Mammals like polar bears

11. A marine food chain A marine food chain Polar bear - 5 Seal - 4 Cod - 3 Krill - 2 Algae - 1

12. A terrestrial-based food chain A Terrestrial food chain Hawk � Snake eaten by hawk Frog eaten by snake Grasshopper eaten by frog

13. Impact of pesticides (i.e., DDT) on the species of an ecosystem

14. Interactions among species in an Ecosystem Plants compete amongst themselves for: 1. water, 2. nutrients 3. sunlight and 4. space Animals compete over 1. food, 2. water, 3. mating and 4. territory 2 main types of relationships Predation � one species (the predator) feeds on the other (prey) e.g. cat and mouse Symbiosis � species live in an intimate association with each other

15. Types of symbiotic relations Parasitism - one species feeds on another (the host) and may kill it. Mutualism � both parties benefit equally from the relationship (flowers and butterflies) Commensalism � the relationship benefits one species but neither helps nor harms the other

16. Principles of Ecology First Law of Energy: �energy can be converted from one form to another but cannot be created or destroyed� Second Law of Energy: �whenever energy is converted from one form to another, a certain amount is lost in the form of heat�. The Law of Conservation of Matter �Although matter can be changed from one form to another it can neither be created nor destroyed by ordinary physical and chemical changes�.

17. Biogeochemical Cycles Comprise processes through which elements that sustain life (water, carbon, phosphorus and nitrogen) are continuously made available to living organisms. Nitrogen cycle Hydrological cycle Carbon cycle Phosphorus cycle

18. The Hydrological Cycle

19. The Carbon Cycle

20. Interruptions in an Ecosystem Causes: a) Natural causes � volcanic eruptions b) Human causes � e.g. construction, agriculture, mining, etc. List some of the consequences that can result from an abrupt interruption in the smooth functioning of an ecosystem?

21. What lessons can we learn from the way a natural ecosystem operates? Natural ecosystems gain resources, use it and dispose of wastes through recycling. Ecosystems sustain themselves by running on Solar Energy which is exceedingly abundant, nonpolluting, constant and long lasting. Far less of Carnivores can be supported by each ecosystem. Many would soon face extinction Every species in a community play an important role in the sustenance of the ecosystem