The pyramid of biomass is an essential concept in ecology that illustrates the distribution of biomass at different trophic levels in an ecosystem. It provides insight into how energy and matter flow through food chains and how living organisms sustain themselves at various levels.
An upright pyramid of biomass is the most common type of biomass pyramid found in terrestrial ecosystems. It shows that producers (plants) have the highest biomass, while the biomass decreases progressively at each higher trophic level. This pattern reflects the loss of energy as it moves through the food chain due to metabolism, heat loss, and other biological processes.
This topic will explain the characteristics, construction, and significance of an upright biomass pyramid while providing examples and real-world applications.
What Is a Pyramid of Biomass?
A pyramid of biomass represents the total dry mass of organisms present at each trophic level in an ecosystem. Biomass is measured in units such as grams per square meter (g/m²) or kilograms per hectare (kg/ha).
There are two main types of biomass pyramids:
- Upright Pyramid of Biomass – Common in terrestrial ecosystems, where producers have the greatest biomass and the biomass decreases at higher levels.
- Inverted Pyramid of Biomass – Seen in some aquatic ecosystems, where the biomass of primary consumers exceeds that of producers due to rapid turnover rates of phytoplankton.
Steps to Construct an Upright Pyramid of Biomass
1. Identify the Ecosystem
The first step in constructing a biomass pyramid is selecting a specific ecosystem. Examples of ecosystems with an upright pyramid of biomass include:
- Forests (e.g., tropical rainforests, temperate woodlands)
- Grasslands (e.g., savannas, prairies)
- Farmlands (e.g., wheat fields, rice paddies)
2. Determine the Trophic Levels
An upright biomass pyramid consists of different trophic levels, arranged from producers at the base to top predators at the peak. The primary levels include:
- Producers (Autotrophs) – Plants, algae, or photosynthetic bacteria that generate energy through photosynthesis.
- Primary Consumers (Herbivores) – Animals that eat producers, such as deer, rabbits, and grasshoppers.
- Secondary Consumers (Carnivores/Omnivores) – Predators that feed on herbivores, such as foxes and snakes.
- Tertiary Consumers (Top Predators) – Carnivores that eat other carnivores, such as eagles, wolves, and lions.
3. Measure Biomass at Each Trophic Level
Biomass is measured using dry weight, which eliminates water content for accurate comparisons. The process involves:
- Collecting a sample of organisms from each trophic level.
- Drying the samples in an oven at 60-100°C until all water is removed.
- Weighing the dry mass of organisms.
- Multiplying by the estimated population size to determine total biomass at that level.
4. Construct the Pyramid Shape
Once biomass values are calculated, they are arranged in a pyramid format:
- The base (producers) has the widest section, representing the highest biomass.
- Each higher trophic level decreases in width, showing a decline in biomass.
- The top predator has the smallest biomass, as energy is lost through respiration, heat, and biological activities.
Example of an Upright Pyramid of Biomass
Tropical Grassland Ecosystem
| Trophic Level | Organism Example | Biomass (kg/m²) |
|---|---|---|
| Tertiary Consumers | Lions | 0.1 |
| Secondary Consumers | Jackals | 1 |
| Primary Consumers | Zebras, Antelopes | 10 |
| Producers | Grasses, Shrubs | 100 |
In this example, grasses have the largest biomass, while lions at the top of the pyramid have the smallest biomass due to energy loss at each level.
Why Is the Pyramid of Biomass Upright?
1. Energy Loss at Each Trophic Level
Only about 10% of energy is transferred from one trophic level to the next, while 90% is lost as:
- Respiration and metabolic processes
- Heat dissipation
- Excretion and decomposition
2. Larger Producer Biomass Supports the Food Chain
In terrestrial ecosystems, plants form a large biomass base that supports herbivores and predators. Without sufficient plant biomass, higher trophic levels cannot survive.
3. Longer Life Span of Producers
Trees, shrubs, and grasses have longer life spans compared to herbivores and carnivores. This ensures a stable and sustainable biomass pyramid.
Significance of an Upright Pyramid of Biomass
1. Ecological Stability
A well-balanced biomass pyramid ensures sustainability in an ecosystem. If producer biomass declines, the entire food web collapses.
2. Conservation Efforts
Understanding biomass distribution helps in wildlife conservation, preventing overhunting or deforestation that could disrupt the balance.
3. Agriculture and Food Security
Farmers use biomass data to enhance crop production, ensuring a stable food supply for both humans and livestock.
4. Climate Change and Carbon Storage
Forests and grasslands store carbon through biomass accumulation. Protecting these ecosystems helps in reducing CO₂ levels and combating climate change.
Threats to the Upright Pyramid of Biomass
Despite its stability, several human activities threaten biomass pyramids:
1. Deforestation
Cutting down forests reduces producer biomass, leading to food shortages for herbivores and carnivores.
2. Overhunting and Poaching
Excessive hunting of primary or secondary consumers disrupts the natural food chain.
3. Pollution and Habitat Destruction
Pollution affects plant growth and animal survival, reducing biomass at all levels.
4. Climate Change
Rising temperatures, droughts, and extreme weather events alter ecosystem balance, impacting biomass pyramids.
How to Preserve the Pyramid of Biomass
1. Reforestation and Afforestation
Planting trees and restoring forests increases producer biomass and stabilizes ecosystems.
2. Sustainable Farming Practices
Crop rotation, organic farming, and controlled grazing help maintain biomass balance in agricultural lands.
3. Wildlife Protection Laws
Governments and conservation organizations enforce anti-poaching laws to protect animals in the food chain.
4. Reducing Carbon Emissions
Lowering greenhouse gas emissions helps mitigate climate change, preserving natural biomass pyramids.
An upright pyramid of biomass is a fundamental concept in ecology, demonstrating the flow of energy and matter in ecosystems. It highlights how producers sustain herbivores and predators, ensuring ecological stability.
By understanding and preserving biomass pyramids, we can promote biodiversity, protect wildlife, and support sustainable ecosystems. Responsible conservation efforts and environmental awareness are essential in maintaining a healthy balance in nature.