Biol120 - Lecture 10: Plants as Habitats & Food

Importance of Plants

  • Compose ≈80%80\% of Earth’s biomass (≈450 Gt C450\,\text{Gt C} of 550 Gt C550\,\text{Gt C} total)
  • Fundamental to ecosystems: oxygen production, carbon fixation, food, shelter, materials
  • Human well-being tied to plants via ecosystem services (health, survival, cultural values)

Plant Blindness

  • Definition: failure to notice / value plants (Wandersee & Schussler, 1999)
  • Causes: animal-centred curricula, visual homogeneity, lack of movement, low perceived threat
  • Consequences: underappreciation → declining support for conservation
  • Remedy: integrate plant science at all education levels; highlight plant roles & interactions

Ecosystem Services Provided by Plants

  • Provisioning: food, medicine, fibres, biofuels, timber, shelter
  • Regulating: CO2\text{CO}_2 sequestration, climate cooling, erosion control, water regulation
  • Supporting: habitat structure, soil formation, nutrient cycling, biodiversity maintenance
  • Cultural: aesthetics, traditions (e.g. Bunya Pine gatherings)
  • Photosynthesis equation: 6 CO<em>2+6 H</em>2O  →sunlight  C<em>6H</em>12O<em>6+6 O</em>26\,CO<em>2 + 6\,H</em>2O \;\xrightarrow{\text{sunlight}}\; C<em>6H</em>{12}O<em>6 + 6\,O</em>2

Agro-biodiversity & Domestication

  • >31,00031{,}000 edible plant spp.; global diet relies on few crops → vulnerability
  • Artificial selection: wild mustard → broccoli, cabbage, kale, cauliflower, kohlrabi
  • Centres of crop origin span all continents (Khoury et al., 2016)

Sustainable Land-Use & Carbon Farming

  • Practices: agroforestry, cover crops, rotational grazing, reduced tillage, low chemical input
  • Outcomes: trap CO2CO_2, build soil carbon, enhance fertility, boost resilience & productivity

Plant–Soil–Organism Interactions

  • Plants shape terrestrial food webs; litter fuels decomposers → nutrient release
  • Plant-soil feedbacks: positive loops enhance microbes, carbon allocation, subsequent plant growth

Inter-Plant & Plant–Microbe Relationships

  • Mycorrhizae in 80−90%80{-}90\% of plant spp.: mutual nutrient exchange
  • Parasitic plants: hemi- & holoparasites (e.g. mistletoes, dodder)
  • Epiphytes & lianas: non-parasitic, use hosts for support

Plant–Animal Interdependence

  • Specialist herbivores (e.g. monarch–milkweed)
  • Pollinators require flowering plants; animals need plant-derived habitat
  • Defensive mutualisms: ant armies protect acacias

Climate Regulation & Cooling

  • Transpiration + shade lower ambient temperature; promote cloud formation
  • Forests & wetlands act as carbon sinks; vegetation loss amplifies warming

Threats & Conservation Needs

  • Rapid, often silent decline in plant biodiversity; Australia among top deforestation nations
  • Loss undermines ecosystem services, cultural heritage, global climate stability
  • Focus attention on plant diversity, structure & function to counteract decline