Ecosystem Interactions & Energy Transfer
GLOBAL SYSTEMS
Four Major Earth Systems:
- Hydrosphere: All water bodies on Earth, including oceans, rivers, lakes, and groundwater.
- Atmosphere: The layer of gases surrounding Earth, essential for weather and climate regulation.
- Geosphere: The solid part of Earth, encompassing rocks, soil, and the land surface.
- Biosphere: The zones of life on Earth, where living organisms interact with each of the other systems.
Abiotic Factors: Non-living chemical and physical parts of the environment that affect ecosystems. Examples include:
- Temperature
- Water availability
- Light
- Soil composition
Biotic Factors: Living components of an ecosystem, such as:
- Plants
- Animals
- Microorganisms
Impact of Abiotic Factors: Abiotic conditions can greatly influence organism survival, growth, and reproduction.
- Example: Temperature extremes can limit species distribution.
Ecological Terms:
- Species: A group of organisms that can interbreed.
- Population: All members of a species in a given area.
- Community: Different species living and interacting in a particular area.
- Ecosystem: Community plus abiotic factors.
- Biome: A large region characterized by specific climate and ecological conditions.
Niche: The role or function of an organism or species within an ecosystem, including its habitat, resource use, and interactions with other organisms.
- Competition: Can be reduced through resource partitioning in overlapping niche areas.
Major Biomes: Includes forests, grasslands, deserts, and tundras. Each has unique climatic conditions and species typical to it.
POPULATION ECOLOGY & POPULATION DYNAMICS
Main Characteristics of Populations:
- Geographic Distribution: Range or area that populations occupy.
- Density: Number of individuals per unit area.
- Growth Rate: The increase or decrease in population size over time.
Population Distribution Types:
- Random: Individuals are spaced randomly.
- Clumped: Individuals are grouped in patches.
- Uniform: Individuals are evenly spaced.
Regulators of Population Growth: Factors affecting the size of populations, including:
- Birth rates
- Death rates
- Immigration and emigration
Population Size Formula: The basic formula considering birth, death, immigration, and emigration rates.
Limiting Factors: Environmental conditions that limit the growth, abundance, or distribution of an organism or population. Examples include:
- Food availability
- Predation
Density-Dependent vs. Density-Independent Factors:
- Density-Dependent: Factors that have greater impact at higher population densities (e.g., competition, disease).
- Density-Independent: Factors affecting population regardless of size (e.g., natural disasters).
Survivorship Patterns: Reflects how death rates vary with age. Types include:
- Type I: High survival rates in early life; older ages have high mortality.
- Type II: Constant mortality rate throughout lifespan.
- Type III: High mortality in early life, but if survive, live long.
Exponential Growth: Occurs when resources are unlimited, leading to a rapid increase in population size.
- Mathematical Model: N(t) = N_0 e^{rt} where:
- N(t) = population size at time t
- N_0 = initial population size
- r = growth rate
Logistic Growth: Population growth slows as it approaches carrying capacity (the maximum population size an environment can sustain).
Carrying Capacity: The maximum population size that an environment can sustain indefinitely.
Types of Species Interactions:
- Predation: One species benefits, the other is harmed.
- Mutualism: Both species benefit.
- Commensalism: One species benefits, the other is neither helped nor harmed.
- Parasitism: One species benefits at the expense of the other.
Interspecific Competition: Competition between different species for resources.
Intraspecific Competition: Competition among members of the same species.
ENERGY FLOW
Energy Flow: Energy flows through an ecosystem from producers to consumers in food chains and webs.
Food Chains vs. Food Webs:
- Food Chain: Linear sequence of energy transfer through feeding relationships.
- Food Web: Complex network of feeding relationships in an ecosystem.
Autotrophs vs. Heterotrophs:
- Autotrophs: Organisms that produce their own food (e.g., plants).
- Heterotrophs: Organisms that consume other organisms for energy (e.g., animals).
Consumer Levels:
- 1st Level (Producers): Organisms that produce energy.
- 2nd Level (Primary Consumers): Herbivores that eat producers.
- 3rd Level (Secondary Consumers): Carnivores that eat herbivores.
10% Rule: When energy is transferred from one trophic level to the next, only about 10% is passed on. The rest is lost as heat.
Trophic Level: The position of an organism in a food web, which indicates its role in the energy transfer.
Energy Loss: Energy not passed to the next level is primarily lost as heat or used for metabolic processes.
Ecological Pyramids: Graphical representation showing the relationship between energy levels in a food chain or web, typically pyramidal in shape, indicating energy flow and biomass at each trophic level.
CYCLES OF MATTER
Major Nutrients: Key nutrients include carbon, nitrogen, phosphorus, and water.
Nutrient Flow: Nutrients cycle through ecosystems via biogeochemical cycles.
Water Cycle: Processes include evaporation, condensation, precipitation, infiltration, and runoff.
Carbon Cycle Processes: Key processes include:
- Photosynthesis
- Respiration
- Decomposition
- Combustion
- Sedimentation
- Fossilization
- Volcanic activity.
Sources of Carbon Dioxide: Natural sources include respiration and volcanic eruptions; anthropogenic sources include fossil fuel combustion and deforestation.
Nutrient Cycle Interactions: Nutrient cycles are interconnected, affecting one another’s flow and availability.
Element Form Changes: Elements change form during their cycles, often resulting in various chemical compounds.
Human Interferences: Humans impact nutrient cycles through pollution, deforestation, and industrial activities, disrupting ecological balance.