FINALS

• • Living organisms occupying a given habitat are exposed to conditions which are largely defined by the nature of the physical environment they inhabit.
• • T or F: Living organisms occupying a given habitat are exposed to conditions which are largely defined by the nature of the physical environment they inhabit. (TRUE)
• • Various abiotic factors that comprise the environment 
  • the prime determiners of the abundance, distribution and over-all ecology of the biotic units of the ecosystem. 
• • Biotic components include:
  • Producer
  • Consumers
  • Decomposers
• • Abiotic components 
  • the complex of physical and chemical factors
• • Abiotic components 
  • include:
  • climatic factors 
  • edaphic factors 
  • topographic factors 
• • climatic factors 
  • Light
  • Temperature
  • Humidity
  • Wind
  • Precipitation
• • edaphic factors 
  • Soil nutrient
  • Acidity
  • Moisture
• • topographic factors 
  • Aspect
  • Angle of slope
  • Altitude
• • A.G. Tansley (1935)
  • the biotic components (organisms) could not be separated from the abiotic (physical factors) with which they form one physical unit, the ecosystem.
• • Climate 
  • result of the interplay of the following factors: 
  • seasonal temperature
  • Humidity
  • Wind
  • Precipitation
  • Light conditions. 
• • Weather  
  • momentary conditions of the atmosphere. 
• • Climate and weather 
  • affect the distribution and activity of both terrestrial and aquatic organisms.
• Laboratory thermometer - Field instrument used to measure temperature
• Light meter - Field instrument used to measure light intensity
• Slingshot psychrometer - Field instrument used to measure relative humidity
• Wind meter and compass - Field instrument used to measure wind speed and direction
• Barometer - Field instrument used to measure atmospheric pressure
• Rain gauge - Field instrument used to measure precipitation
• Aluminum pans - Field instrument used to measure rate of evaporation
• Climatological factors

  • Temperature
  • Light Intensity
  • Relative Humidity
  • Wind Speed and Direction
  • Atmospheric Pressure
  • Precipitation
  • Rate of Evaporation
• Ecological significance

  • Light - Photosynthesis; energy reservoir
• Ecological significance

  • Temperature - regulate rate of growth, development, metabolism, and reproduction
• Ecological significance

  • Humidity - influence water balance and respiration; cloud formation and precipitation
• Ecological significance

  • Wind - role in seed, pollen, and spores dispersal; climate patterns, temp control, rate of evaporation
• Ecological significance

  • Precipitation - primary source of freshwater; water availability; soil formation, and nutrient cycling
• Ecological significance

  • Temperature - all biological processes
• Climatic factors with ecological interactions (Wind and precipitation)

  1. Wind for seed dispersal and Precipitation that can limit its distribution.
  2. Low rainfall, strong winds can blow seeds before germination.
  3. Heavy rainfall, saturate soils impeding germination
• Climatic factors with ecological interactions (Humidity and temperature)

  1. Affects the abundance and distribution of organisms by their ability to adapt to maintain water balance
  2. Hot and humid envi, organisms lose excess water
  3. Hot and arid envi, organisms and rapid water loss
• Relative Humidity (RH)

  • vapor pressure of water in the air expressed as a percentage of the saturation pressure.
• Relative humidity is the ratio of the actual vapor pressure of water in the air to the saturation pressure at that temperature, expressed as a percentage.
• Relative Humidity

  • Higher temperature / warmer air means lower RH
  • Lower temp / cooler air means higher RH
• factors affecting light intensity in a terrestrial habitat

  • sun angle
  • Seasonal changes, 
  • cloud cover, 
  • latitude, 
  • topography, and 
  • vegetation density 
• factors affecting light intensity in a aquatic habitat

  • depth due to water absorption and scattering
  • turbidity
  • angle of sunlight
  • ice cover
• Temperature and capacity to hold water vapor

  • Warmer air / high temp has a higher capacity to hold water vapor, resulting in lower RH if the water vapor remains constant
  • Cooler air / low temp has decreased water vapor capacity, resulting in higher RH for the same water vapor content
• Relative Humidity and Water Loss

  • In low RH envi, organisms lose water faster because of higher water vapor capacity creating diffueion (water from organisms to dry air regions)
  • In high HR envi, organisms have slower water loss due to lower water vapor capacity
• Precipitation rate and atmospheric pressure

  • Lower atm pressure, increased precipitation because of rising air that cools and condenses
  • Higher atm pressure, reduced precipitation because of clear skies
• Wind velocity and animal activity & plant transpiration

  • High wind speeds often lead to reduced activity levels in small animals due to increased energy expenditure required for movement against strong winds. 
  • High wind speed increases plant transpiration through the removal of humid air surrounding leaves, resulting in a vapor pressure gradient that drives water vapor diffusion into drier air.
• • Soil 
  • the weathered superficial layer of the earth’s crust comprised of minerals and organic matter and is capable of supporting plant growth (Smith, 1980).
• • Aside from the plants a great number of micro and macroinhabitants dwell in the soil medium. The burgeoning and survival of all of these organisms, therefore, will be dependent on factors related to the soil itself.