Ecosystem

• Environment


  Anything that affects an organism in its lifetime
• Types of environmental influences

  • Biotic (living things affecting other organisms)
  • Abiotic (nonliving components affecting organisms such as temperature, soil, and pH)
• Ecology


  The branch of biology that studies the interactions between organisms and their environment
• Ecosystem


  Composed of the organisms in an area that are interacting with both biotic and abiotic factors
• Organism


  The smallest unit of an ecosystem
• Niche


  The ecological role of an organism in a given community
• Population


  A group of organisms of the same species
• Community


  Various species that constitute different populations of species
• Abiotic components


  • Climate
  • Weather
  • Minerals
  • Water
  • Air
  • pH
  • Salinity
  • Temperature
  • Soil
  • Sunlight
• Food chain


  A linear sequence of organisms through which energy and nutrients pass as one organism feeds on another organism
• Food web


  A network of interconnected food chains
• Trophic levels


  • Producers
  • Primary consumers
  • Secondary consumers
  • Tertiary consumers
• Biomass


  The weight of the organisms at a trophic level
• The energy of an ecosystem can also be measured by looking at the processes of photosynthesis and respiration
• Trophic level


  A step or stage in the flow of energy through an ecosystem
• Natural ecosystem


  Results from the interaction between organisms and their environment, composed of biotic and abiotic components
• Components of a natural ecosystem


  • Producers
  • Consumers
  • Decomposers
• Terrestrial ecosystem


  Land-based interactions of biotic and abiotic factors in a given geographic area
• Aquatic ecosystem


  Water-based, can be classified as freshwater or marine
• Biome


  A specific geographic area notable for the species that live there
• Key factors determining biomes

  • Temperature
  • Precipitation (moisture)
• Terrestrial biomes


  • Tropical rainforest
  • Savanna
  • Desert
  • Grassland
  • Temperate deciduous forest
  • Temperate evergreen forest
  • Taiga
  • Tundra
• Freshwater ecosystem


  Can be categorized as stationary (lakes, ponds) or running (rivers, streams)
• Rivers and streams have conditions that are different from lakes and ponds, with less importance of planktonic organisms due to moving water
• Stationary water ecosystems


  • Lakes - large bodies of freshwater that are relatively still or stationary
  • Ponds - smaller in size than lakes but also stationary
• Lake zones


  • Euphotic zone - top layer with abundant phytoplankton and zooplankton
  • Littoral zone - shallow parts with rooted vegetation
  • Limnetic zone - part with no rooted vegetation
• Running water ecosystems


  • Planktonic organisms less important because water is moving
  • Shallow waters allow light to penetrate bottom
  • Difficult for photosynthetic organisms to obtain needed nutrients, making them less productive
• Freshwater wetlands


  • Intermediate habitats between freshwater and terrestrial environments
  • Highly productive ecosystems that serve as breeding sites
• Types of freshwater wetlands

  • Marshes - shallow wetlands found along rivers
  • Swamps - flooded forests with trees and shrubs
• Marine ecosystems


  • Sunlight penetrates only the uppermost photic zone
  • Aphotic zone is permanently dark with chemoautotrophs as producers
• Marine ecosystem zones


  • Intertidal zone - where ocean meets land
  • Pelagic zone - open ocean
  • Benthic zone - region below pelagic zone
  • Abyssal zone - deepest region of the ocean
• Estuary


  • Shallow, partially enclosed area where freshwater and saltwater mix
  • Highly productive ecosystems due to availability of nutrients and sunlight penetration
• Types of estuaries


  • Salt marshes - temperate-zone estuaries with abundant salt-tolerant grasses
  • Mangrove swamps - coastal wetlands in tropical regions
• Artificial ecosystem


  • Artificial system of organisms within a given area
  • Not self-sustaining, requires human intervention and assistance
• Differences between natural and artificial ecosystems

  • Natural ecosystem - high species diversity, high genetic diversity, long and complex food chains, ecological succession, natural nutrient cycles, sustainable
  • Artificial ecosystem - low species diversity, low genetic diversity, simple and incomplete food chains, no ecological succession, artificial nutrient supply, unsustainable
• Ecological succession


  Series of gradual changes that occur in an ecosystem over time due to natural or human-caused disturbances
• Types of ecological succession

  • Primary succession - new land formation or bare rock populated for the first time
  • Secondary succession - previously inhabited area becomes disturbed and then repopulated
• Primary succession


  1. Weathering breaks down rock

  2. Lichens as pioneer species

  3. Lichens and small plants

  4. Grasses and perennial plants

  5. Grasses, shrubs, and pines

  6. Shade-tolerant trees
• Ecological succession may not always follow a predetermined path, and stable climax communities may be uncommon due to frequent disturbances