Ch 52

• Ecology


  The scientific study of the interactions between organisms and the living and nonliving components of their environment
• Levels of ecological organization

  • Organisms
  • Populations
  • Communities
  • Ecosystems
  • Biomes
  • Biosphere
• Organismal ecology


  • Studies how an organism's structure, physiology, and (for animals) behavior meet environmental challenges
  • Includes physiological and behavioral ecology
• Population ecology


  • Focuses on factors affecting population size over time
• Community ecology


  • Examines the effect of interspecific interactions on community structure and organization
• Ecosystem ecology


  • Emphasizes energy flow and chemical cycling between organisms and the environment
• Landscape ecology


  • Focuses on the exchanges of energy, materials, and organisms across multiple ecosystems
• Global ecology


  • Examines the influence of energy and materials on organisms across the biosphere
• Climate


  The long-term prevailing weather conditions in an area, including temperature, precipitation, sunlight, and wind
• Global climate patterns


  • Determined largely by solar energy and Earth's movement in space
  • The warming effect of the sun establishes temperature variations, circulation of air and water, and evaporation of water
• Angle of sunlight hitting Earth

  Affects the intensity of sunlight, the amount of heat and light per unit of surface area
• The intensity of sunlight is strongest in the tropics (between 23.5° north latitude and 23.5° south latitude) where sunlight strikes Earth most directly
• Global air circulation and precipitation patterns

  1. Water evaporates in the tropics, and warm, wet air masses flow from the tropics toward the poles

  2. Rising air masses release water and cause high precipitation, especially in the tropics

  3. Dry, descending air masses create arid climates, especially near 30° north and south

  4. Air flowing close to Earth's surface creates predictable global wind patterns
• Cooling trade winds blow from east to west in the tropics; prevailing westerlies blow from west to east in the temperate zones
• Climate varies seasonally and is modified by other factors including large bodies of water and mountain ranges
• Seasonality


  Seasonal variations in day length, solar radiation, and temperature increase steadily toward the poles
• Seasonality at high latitudes is caused by the tilt of Earth's axis of rotation and its annual passage around the sun
• Changing angle of the sun

  Affects local environments, causing wet and dry seasons in regions at 20°N and 20°S latitudes
• Seasonal changes in wind patterns

  Alter ocean currents, causing upwelling of cold, nutrient-rich water from deep ocean layers
• Ocean currents


  • Influence the climate of nearby terrestrial environments
  • Currents flowing toward the equator carry cold water from the poles; currents flowing away from the equator carry warm water toward the poles
• Large bodies of water

  Moderate the climate of nearby land
• Mountains


  • Influence air flow over land and affect climate in surrounding areas
  • Warm air cools as it rises up a mountain and releases moisture on the windward side
  • Cool, dry air absorbs moisture from the land as it descends, creating a "rain shadow" on the leeward side
  • Affect the amount of sunlight reaching an area, with south-facing slopes receiving more sunlight than north-facing slopes in the Northern Hemisphere
• Microclimate


  Very fine, localized patterns in climate
• Factors characterizing every environment

  • Abiotic factors (nonliving attributes such as temperature, light, water, and nutrients)
  • Biotic factors (other organisms that are part of an individual's environment)
• Global climate change


  A directional change to the global climate lasting three decades or more
• Burning of fossil fuels and deforestation have increased the concentration of greenhouse gases in the atmosphere, resulting in shifting wind and precipitation patterns, increasing global temperature, and increasing the frequency of extreme weather events
• Past climate change


  Can be used to predict the effects of future global climate change by studying how species responded
• The geographic ranges of many species have shifted in response to climate change
• Determining the location of suitable habitat under different climate scenarios can help predict future range shifts
• Species that have difficulty dispersing or face a shortage of suitable habitat may have smaller ranges or could become extinct
• Biomes


  Major life zones characterized by vegetation type (terrestrial biomes) or physical environment (aquatic biomes)
• The frequency of extreme weather events have increased
• Predicting effects of future global climate change

  • Study how species responded to changes in the past
  • Determine location of suitable habitat under different climate scenarios to predict future range shifts
• American beech


  • Current range
  • 4.5ºC warming over next century
  • 6.5ºC warming over next century
• Terrestrial biomes


  • Usually grade into each other without sharp boundaries
  • The area of intergradation, called an ecotone, may be wide or narrow
• Vertical layering in a forest


  • Upper canopy
  • Low-tree layer
  • Shrub understory
  • Ground layer of herbaceous plants
  • Forest floor
  • Root layer
• Layering of vegetation in all biomes provides diverse habitats for animals
• The species composition of each kind of biome varies from one location to another
• Disturbance


  An event such as a storm, fire, or human activity that changes a community
• Disturbance


  • Frequent fires can kill woody plants and maintain the characteristic vegetation of a savanna
  • Hurricanes create openings in forests that allow different species to grow