GENVI

• Environment

  • Refers to everything surrounding us
  • Composed of the four spheres of the earth: atmosphere, lithosphere, hydrosphere, biosphere
  • Total of all external factors, abiotic and biotic, that affect life
• Ecosystem


  • Biotic and abiotic components together make up an ecosystem
  • Interactions seen in material and energy flows in the ecosystem
  • Material flow occurs in biogeochemical cycles like water cycle, carbon cycle, nitrogen cycle, sulfur cycle, phosphorus cycle
  • Energy flow occurs in different trophic levels involving producers and consumers
  • Material and energy flows sustain life on earth
  • Disruption in flows can have adverse consequences
• Biotic components of the environment

  • Living biological factors such as plants, animals, microorganisms, humans
  • Abiotic processes like predation, competition, migration
• Environmental Science

  • Applied science using ecosystem concepts to identify, understand, and address environmental issues due to human activities
  • Environment is the most important resource for humans
  • Global population growth leads to resource depletion, ecosystem destruction, pollution, climate change
  • Environmental Science is crucial to address environmental decline
• Environmental science covers a wide range of subject matters
• Abiotic components of the environment

  • Non-living physical and chemical factors such as air, water, soil, minerals, sunlight
  • Abiotic processes like weathering, erosion, soil formation, evaporation, condensation, precipitation, etc.
• Biomes


  • Large ecosystems with distinct biotic and abiotic characteristics
  • Provide a life support system for organisms
  • Represent different types of environments where living things thrive
• Various external factors that surround an organism

  Affect how the organism grows, survives, and reproduces
• Environmental Science is interdisciplinary, using information from various disciplines to analyze and address environmental issues
• Environmental science

  • It uses information from various disciplines such as ecology, biology, chemistry, physics, geology, and information technology to analyze and address environmental issues, thus considered as interdisciplinary
  • It covers a wide range of subject matters and issues related to our life support system
  • It is divided into several branches such as environmental engineering, environmental chemistry, and atmospheric science, each dealing with specific issues of the environment
  • All these branches have one goal, to provide solutions to environmental problems
• Address the environmental issues


  • Example: The problem of deforestation can be dealt with the strict implementation of the Chainsaw Act of 2002 and, at the same time, promoting tree-planting and reforestation activities
• Knowledge about the life-supporting environment

  • Example: trees absorb carbon dioxide required for photosynthesis and release oxygen in the process; the oxygen is important for respiration, which in turn releases carbon dioxide. This is part of the carbon cycle
• Steps required in environmental science

  1. Knowledge about the life-supporting environment

  2. Understand the problems that threaten the environment

  3. Address the environmental issues
• Understand the problems that threaten the environment

  • Example: deforestation greatly reduces the number of trees that absorb carbon dioxide from the atmosphere; in effect, greenhouse gases are increased leading to global warming
• Importance of environmental science

  • Enhancing people’s awareness through skill acquisition for solving and identifying environmental problems
  • Providing an opportunity for active involvement in addressing environmental problems
  • Developing the ability to evaluate environmental measures and educational programs in terms of ecological, economic, social, and aesthetic factors
  • Acquiring a set of values and feelings of concern; motivation for active participation to improve and protect the environment
  • Gaining a variety of experiences and acquiring a basic understanding of the environment and its associated problems
  • Acquiring an awareness of the environment as a whole and its allied problems and sensitivity
• Abiotic factors that can be limiting to organisms

  • Water
  • Temperature
  • Salinity
  • pH
  • Light
  • Nutrients
  • Space
• Light as a Limiting Factor

  1. Light affects plant timing and seasonal rhythms

  2. Light is important for photosynthesis reactions
• pH as a Limiting Factor

  1. Acidity or alkalinity affects plant and animal distribution

  2. Soil pH influences factors affecting plant growth

  3. Pine needles can decrease soil pH, inhibiting growth in other plants
• Biotic factors that can be limiting to organisms

  • Interactions such as parasitism, predation, competition
• Temperature as a Limiting Factor

  1. Low temperatures limit physiological activity time

  2. High temperatures impose severe constraints on organisms

  3. Organisms can cool themselves through sweating, panting, defecating

  4. Many organisms are adapted to withstand high temperatures

  5. Pyrophytic plants need fire for seed reproduction

  6. Australian Banksia serrata exhibits pyriscence, an ecological adaptation post-fire
• Biotic factor: Predators


  • Predators make it difficult for their prey to freely roam around and gather or hunt for food, acting as a limiting factor for the prey
• Abiotic factor: Water

  • Water is important for normal organismal metabolic processes
  • Lack of water leads to dehydration, preventing normal functioning and limiting survival
• Salinity as a Limiting Factor

  1. Salt concentrations affect water uptake

  2. Higher salt concentrations increase osmotic resistance to water uptake

  3. Halophytes are plants adapted to withstand highly saline conditions
• Temporal/Time as a Limiting Factor

  1. Breeding season of animals set by response to day length changes

  2. Light used as cue for activity cycles such as hunting

  3. Diurnal animals are active during the daytime and sleep at night

  4. Nocturnal animals are active at night
• Concept of Limiting Factors

  1. Abiotic and biotic factors affect how organisms grow, survive, and reproduce

  2. Environmental factors are important in allowing organisms to function normally and promote survival

  3. An environmental factor may not be enough or may be too much, becoming destructive

  4. Any factor that restricts the ability of an organism (or a population) to grow, survive, or reproduce is an ecological stress called a limiting factor
• Soil Quality as a Limiting Factor

  1. Low nutrient availability associated with low soil temperatures and anaerobic conditions

  2. Soil components affect nutrient availability for each species

  3. Soil development influenced by precipitation, evaporation, vegetation
• Water availability impact

  • Flooded rice field vs Dried up rice field
• Diurnal


  • Active during the daytime and sleep at night
• Breeding season of animals

  Set by the organism’s response to day length changes
• Water availability


  Limits the distribution and abundance of many species
• Liebig formulated the Law of the Minimum based on mineral nutrients and Karl Sprengel’s theorem of minimum
• Liebig’s Law of the Minimum can be used to explain how other limiting factors affect living things
• Water

  • Important for plant growth
• Liebig’s Law of the Minimum


  If any required nutrient is present in minimal amounts, plant growth will be minimal even if other nutrients are abundant
• The balance between nutrients is essential for normal growth, development, reproduction, and to maximize yield
• Deficiency in one nutrient

  Cannot be compensated by a surplus of any other nutrient
• Organisms and environmental conditions


  Organisms thrive in areas with suitable environmental conditions for growth and survival
• Victor Ernest Shelford (1877-1968) formulated Shelford’s Law of Tolerance
• Organisms’ range of tolerance


  • Represents the range within which organisms can tolerate changes in the environment
• Zones of physiological stress

  • Beyond the lower and upper limits of the optimum range