Plant growth and distribution

• Plant growth and distribution
• Human effects on plant growth


  • Improving the growth of crops by ensuring correct soil pH, optimal watering, and correct nutrients present
  • Negative effects like trampling, picking wildflowers, removing hedges/trees (habitat destruction)
• Soil pH

  Most plants grow best in soil with pH between 4.5 and 7.5
• Acidic soil


  Can mean there is a deficiency in necessary minerals, such as iron and manganese
• Soil aeration


  Necessary to allow sufficient oxygen to get to the plant and for carbon dioxide to be removed
• Toxins also form where there is little aeration, such as hydrogen sulfide gas
• Human effects on plant distribution

  • Sowing of crops in fields with only one type of plant
  • Trampling can cause unusual or more widespread distribution patterns due to seeds being carried on the bottom of shoes
• Temperature


  Different plants prefer different temperature conditions to grow, most have an optimum temperature they will grow at, important in seed germination
• Investigating plant growth


  1. Make sure your plan includes detailed enough instructions for someone to be able to follow

  2. Consider your independent, dependent and control variables
• Light, water and minerals are important for plant growth
• Light intensity

  Can affect plant growth, plants need light for photosynthesis, plants in high light intensity are likely to have better growth than those in shade, different parts prefer different light intensity
• Lack of soil moisture

  Decreases rate of photosynthesis, plants cannot take up necessary minerals and nutrients, oxygen is released, carbon dioxide is not absorbed
• Soil pH


  Measure of acidity or alkalinity of soil
• Plants


  • Sensitive to changes in pH
  • Most grow best in neutral or slightly acidic soil
  • pH range of most soils is between 4.5 and 7.5
  • Some grow better in more extreme conditions (pH 3 to 9)
• Soil aeration


  Oxygen availability in the soil
• Importance of soil aeration

  • For plants to respire
  • For microorganisms to respire and decompose organic matter/nitrify soil
  • To help plants absorb water and nutrients
  • To prevent toxins forming
  • To prevent plant diseases
• Photosynthesis


  Plants make food using carbon dioxide, water and energy from sunlight
• Temperature


  • Some plants grow well in cooler climates (e.g. broccoli, spinach)
  • Some plants grow better in warmer climates (e.g. oranges, bananas)
  • Extremes of temperature lead to lack of plant growth
  • High temperatures can cause respiration to take place more quickly than photosynthesis, using up photosynthesis products
  • Low temperatures result in poor growth as photosynthesis is too slow
  • Temperatures below 0°C can destroy plant cells and tissues, killing many plants
• Water is essential for plant growth as it helps transport nutrients and dissolved minerals throughout the plant.
• The main factors affecting plant growth are light, water, temperature, carbon dioxide, nutrients, oxygen, gravity, and competition.
• Excessive rainfall can also harm plants by causing root rot and fungal disease.
• Light intensity affects plant growth through photosynthesis, with higher intensities leading to faster growth rates.