Ecological pyramids in different ecosystems
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Ecological pyramids visually depict the distribution of energy, biomass, or organism numbers across trophic levels in ecosystems, with three main types: pyramid of numbers, pyramid of biomass, and pyramid of energy. Each pyramid can vary in shape (upright, inverted, or spindle), reflecting the relationships between producers, consumers, and their energy transfer. These pyramids are crucial for understanding ecosystem health, guiding conservation efforts, and assessing human impact on nature.
Ecological pyramids in different ecosystems
- 2. Introduction to Ecological Pyramids Definition: Ecological pyramids visually represent the distribution of energy, biomass, or number of organisms across the trophic levels within an ecosystem. 1 The concept of pyramid of numbers ("Eltonian pyramid") was developed by Charles Elton (1927). 2 Trophic Levels: Different levels in a food chain (Producers, Primary Consumers, Secondary Consumers, Tertiary Consumers). 3 Purpose: To illustrate energy flow, mass of living material, or the population size at each level. 4 Types of Pyramids: •Pyramid of Energy •Pyramid of Biomass •Pyramid of Numbers 5
- 3. Graphical representation of the trophic structure is done by drawing ecological pyramids, where the basal, mid and top tiers show the parameter values for producers, herbivores and carnivores in the ecosystem. An ecological pyramid may be upright (tapering towards the tip) or inverted (widens towards the tip) or spindle shaped (broader in the middle and narrow above and below). Introduction to Ecological Pyramids
- 4. PYRAMID OF NUMBERS Pyramid of numbers is the graphic representation of number of individuals per unit area of various trophic levels stepwise with producers forming the base and top carnivores the tip. The shape can be upright or inverted depending on the ecosystem and types of organisms.
- 5. Pyramid of Numbers Grassland Ecosystem (Upright Pyramid of Numbers) • Producers: Numerous grasses make up the base, as they are abundant and support the herbivores. • Primary Consumers: Rabbits and grasshoppers, fewer in number than grasses, consume the producers. • Secondary Consumers: Fewer predators (such as small birds or foxes) eat the herbivores. • Tertiary Consumers: Apex predators (like hawks) are the fewest in number at the top.
- 6. Pyramid of Numbers in an Aquatic Ecosystem • The producers are smallest sized but maximum in number while, top carnivores are larger in size but lesser in number, so these cannot be used as prey by another. • Hence the pyramid of numbers is upright
- 7. Forest Ecosystem (Inverted Pyramid of Numbers) • Producers: Few large trees support the entire ecosystem. • Primary Consumers: Numerous herbivores like insects depend on the trees. • Secondary Consumers: Birds that feed on insects are fewer in number. • Tertiary Consumers: Apex predators, such as hawks or owls, are at the top with the least numbers. • When a large tree support larger number of herbivorous birds which in turn are eaten by carnivorous birds like falcon and eagle, which are smaller in number, it forms a spindle shaped pyramid
- 8. PYRAMID OF BIOMASS Pyramid of biomass is the graphic representation of biomass present per unit area of different trophic levels, with producers at the base and top carnivores at the tip". The total amount of living or organic matter in an ecosystem at any time is called 'Biomass'. Usually upright, as biomass decreases with each trophic level due to energy loss and less overall mass at higher levels. Biomass is measured in grams per square meter (g/m²) or kilograms per hectare.
- 9. Forest Ecosystem • Producers: Trees and large plants have the highest biomass due to their size and longevity. • Primary Consumers: Herbivores (such as deer or insects) have a lower biomass as they rely on the producers. • Secondary Consumers: Carnivorous animals like foxes and birds have an even smaller biomass. • Tertiary Consumers: Apex predators like wolves or hawks have the smallest biomass due to energy and biomass reduction at each level.
- 10. Inverted Biomass Pyramid: Aquatic Ecosystem • In certain aquatic ecosystems, the biomass pyramid may appear inverted. • Producers: Phytoplankton (tiny, fast- reproducing organisms) have a low biomass but high turnover rate, supporting higher levels. • Primary Consumers: Zooplankton, which feed on phytoplankton, may have a greater total biomass. • Higher Consumers: Fish and larger aquatic predators have more biomass than the producers due to the high reproduction and consumption rate of phytoplankton.
- 11. PYRAMID OF ENERGY • Pyramid of energy is a graphic representation of the amount of energy trapped per unit time and area in different trophic level of a food chain with producers forming the base and the top carnivores at the tip. • Shows the amount of energy available at each trophic level, typically measured in kilojoules (kJ) or calories. • About 10% of energy is transferred to the next level, while 90% is lost as heat or in metabolic processes (as per Lindeman's ten percent rule). • This makes the energy pyramid always upright, with a broad base of energy at the producer level and decreasing energy at higher trophic levels.
- 12. Grassland Ecosystem • Producers: Grasses have the most energy available since they convert sunlight to chemical energy via photosynthesis. • Primary Consumers: Herbivores (like grasshoppers) consume grasses but receive only about 10% of the energy originally captured. • Secondary Consumers: Small birds that eat grasshoppers get only about 1% of the energy. • Tertiary Consumers: Hawks at the top receive the least energy, around 0.1% of the original input from producers.
- 13. Factors Influencing Pyramid Shapes Energy Transfer Efficiency: Only 10% of energy is transferred up each trophic level. Consumer-Producer Ratios: Ecosystems with few large producers (like trees) may have inverted number pyramids. Ecosystem Type: Aquatic ecosystems often have inverted biomass pyramids, while terrestrial ecosystems generally follow upright shapes.
- 14. Comparison of Pyramid Types Pyramid of Energy: Always upright; reflects energy flow and is crucial for understanding ecosystem productivity. Pyramid of Biomass: Generally upright but may invert in aquatic ecosystems with rapid producer turnover. Pyramid of Numbers: May vary in shape; reflects population size rather than mass or energy.
- 15. Importance of Ecological Pyramids in Ecology and Conservation Ecosystem Health: Helps monitor the balance between species and predict impacts if a trophic level is disrupted. Conservation and Management: Guides conservation strategies by identifying keystone species, tracking energy efficiency, and understanding food web dynamics. Human Impact: By observing ecological pyramids, scientists can evaluate the impact of human activities on ecosystems and develop strategies for sustainable resource management.