7A

• Environment - complex of climatic, edaphic, and biotic factors that act on organism and ultimately determine its form and survival
• Ecology - the science that deals with the

  reciprocal relations between organisms and

  their environment.
• Plant Ecology - involves investigation of the relationship of

  plants to the physical, biotic and physiological aspects of

  the environment
• Physiological Ecology – the field that deals on

  how plants grow in their natural environment.
• Plant Ecosystems – dynamic aspects of the

  vegetation, the flora and the environmental

  factors
• Vegetation: encompasses the type of plants that

  subsist in a region, within the limitations imposed by

  the climate and the environment
• Flora: the group of actual species of plants that makes

  up the vegetation of a region
• Ecology - the study of the interactions of organisms with their environment
• Levels of organization in ecology

  1. Organism (physiological) – how the individual meets the challenges of its physicochemical environment
  2. Population – a group of individuals in a particular geographic area that belong to the same species
  3. Community – an assemblage of populations of different species that inhabit a particular area
  4. Ecosystem – includes all the abiotic factors as well as the community of species that exists in a certain area
  5. Biosphere – the part of the Earth that contains all ecosystems
• Some Principles of Plant Response to Environment

  Saturation concept - the organism utilizes the factor being considered until its capacity for utilization is used up
• Dose-response curve

  Deficiency zone – increased response

  Tolerance zone – no change in response

  Toxicity zone – decreased response
• Limiting factor concept (Liebig’s Law of the Minimum)

  • plant growth is dependent upon the amount of “foodstuff”

  presented to it in minimum quantities

  • limiting factors might be mineral nutrients, water, damage by pests, weed competition, CO2 concentration, or the plant’s genes
• Interactions of Factors

  Synergism – response together greater than sum given alone additive factors

  Additive – different causal consequence

  Multiplicative – different steps on the same causal sequence
• Climate


  exerts a strong control over a plant’s requirement for nutrients, water & energy, resistance to parasites, salinity, flooding and other injurious factors
• The disturbance of one factor can trigger a series of changes connected to the disturbed factor
• The separate effects of two factors may not be the

  same when the two factors are combined

  ◦ SYNERGISM (opposite response is ANTAGONISM) when the

  two factors interact in such a way that the response to a

  combination of the two is greater than the sum of the

  separate response for each
• Types of Plant Response to Environment

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• Factors Affecting Ecological Plant Distribution

  1. Water
  2. Temperature
  3. Light
  4. Soil
  5. Atmosphere
  6. Genetics