Carrying Capacity and Competition for Limited Resources
- Ecosystems can only support a certain number of individuals before resources run out.
- This limit is called the carrying capacity, the maximum number of individuals of a species that an environment can support indefinitely.
What is Carrying Capacity?
Definition
Carrying capacity
Carrying capacity is the maximum population size that an ecosystem can sustain indefinitely without degrading the habitat.
- It depends on the availability of resources like food, water, and shelter.
- Changes in climate, natural disasters, and human activity can alter carrying capacity.
- Carrying capacity is not static.
- It changes with environmental conditions and human activities, such as deforestation or pollution.
A lake may support 500 fish under normal conditions, but a drought reducing water levels could lower its carrying capacity.
Competition for Limited Resources
- When resources are scarce, individuals must compete to survive.
- There are two types of competition:
- Intraspecific Competition – Between members of the same species competing for food, space, or mates.
- Interspecific Competition – Between different species competing for the same resources.
Lions and hyenas compete for prey in the savanna.
TipIn questions about competition, always specify whether it’s intraspecific (same species) or interspecific (different species).
Examples of Limited Resources Affecting Carrying Capacity
For Plants:
- Light Intensity – Taller plants block sunlight, reducing photosynthesis for smaller plants.
- Water Supply – Essential for growth; drought conditions reduce plant populations.
- Soil Nutrients – Key minerals like nitrogen, phosphorus, and potassium are often limited.
For Animals:
- Food Supply – Herbivores compete for plants, while carnivores compete for prey.
- Water Availability – Especially critical in deserts or during dry seasons.
- Space & Territory – Needed for nesting, breeding, and hunting; territorial animals may fight over land.
- Oxygen Levels – Aquatic animals compete for dissolved oxygen in water.
- Don’t confuse carrying capacity with the maximum population size ever recorded.
- Carrying capacity is about sustainability, not temporary peaks.
Real-World Examples of Carrying Capacity
1. Creosote Bush in the Desert
- In the Chihuahuan Desert, creosote bushes grow with large gaps between them.
- Their extensive root systems absorb nearly all available water in the soil, preventing other bushes from growing nearby.
- Think of carrying capacity as a balancing act between resource availability and population needs.
- When the balance tips, populations adjust through competition and natural selection.
When discussing plant competition, always mention light, water, and nutrients as limiting factors.
2. Wildebeest in the Serengeti
- During the dry season, water and grass become scarce, limiting population size.
- The wildebeest population declines as individuals compete for dwindling resources.
- When the rains return, grass and water increase, allowing the population to grow again.
- Avoid assuming populations grow indefinitely.
- Populations only grow until they reach the carrying capacity, where resources limit further growth.
- Imagine a crowded concert where everyone is trying to get a drink from a single water fountain.
- As more people gather, the competition intensifies, and not everyone gets what they need.
- This is similar to how populations compete for limited resources in nature.
Why Carrying Capacity Matters
- Ecosystem Stability – Predicts how populations respond to environmental changes.
- Conservation Efforts – Helps manage wildlife populations and prevent overpopulation or extinction.
- Human Impact – Deforestation, pollution, and climate change reduce carrying capacity, threatening biodiversity.
- How does the concept of carrying capacity apply to human populations?
- Consider the ethical implications of resource distribution and sustainability.
Reflection and Review
- Competition for limited resources regulates population size through intraspecific and interspecific competition.
- Carrying capacity determines the maximum population an ecosystem can support.
- Real-world examples include creosote bushes competing for water and wildebeests struggling during the dry season.
- Why does competition limit population size?
- How does carrying capacity regulate ecosystems?
- What factors influence carrying capacity in different ecosystems?
