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:

  1. Photosynthesis
  2. Respiration
  3. Decomposition
  4. Combustion
  5. Sedimentation
  6. Fossilization
  7. 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.