Week 3

• Prior to human settlement 85-90% was heavy forest, this has been influenced by human activity, mainly for food production
• Today the amount of indigenous forest is low (23.8%) and pasture is high (39.8%) significant amount of land transitioned for primary production and agriculture
• Polynesian ancestors of Māori occupied NZ 800 years ago


  1. Resources were abundant

  2. Birds (like Moa), fish, eels, shellfish, seals now largely wiped out

  3. Harvested fruit from the forest, also from cultivated gardens

  4. Introduced plants and animals such as Kumra, taro, ti pore (cabbage tree), rats and dogs
• Captain Cook and early settlers introduced

  1. Chickens, goats and pigs

  2. Whalers, sealers, and missionaries also had an impact bringing sheep, potatoes, crops, purchased large amounts of land through the NZ Company
• Significant land clearance


  1. Using the common fire method

  2. Destroyed 40% of forest in 200 years

  3. Timber utilised for export and building towns

  4. Clearance for pasture and agriculture
• Wetlands are highly productive ecosystems and key for mahinga kai
• 90% of wetlands lost since European settlement, chch and akl used to have significant wetlands
• Returning soldiers from WWI and WWII were given land

  1. Depression in 1930s resulted in work relief schemes- planting of exotic forests in central North Island

  2. Post WWII technology was enhanced, ariel top dressing enabled widespread fertiliser application

  3. Heavy machinery made draining wetlands easier
• The intensity and scale of dairying has vastly increased, used to occur in areas with high rainfall e.g Waikato, Taranaki
• Canterbury, Otago and Southland, dairying has doubled, requiring significantly more irrigation
• Conversion from exotic forest to dairying
• There have been significant changes to the terrestrial environment in Aotearoa, particularly from human activity and changes for food production
• Agriculture is the main land use in New Zealand and is intensifying, resulting in ongoing environmental impacts
• Why NZ is considered a biodiversity hotspot

  • Unique flora and fauna due to long isolation period
  • High proportion of endemic species (90% land-based animals, 80% plants, 38% marine animals)
  • Split from Gondwana 85 MYA, species already present or floated through currents and wind
  • Indigenous animals and plants developed in isolation for 60-80 MYA
  • Fauna is bird and insect based with bats being the only indigenous land mammals
  • Examples: totara, tuatara, rimu, kiwi, kauri snail, weta, manuka, flax, Pohutukawa, saddleback, kokako
• Biodiversity is key for Māori, Kaitiakitanga central to identity and care for taonga species
• Terrestrial ecosystems recognised by DOC

  • 78 zonal (climate, temperature and moisture availability, e.g. sub-Antarctic, alpine, subtropical)
  • 74 azonal (extreme rock and soil chemistry, extreme heat, and frequent disturbance, e.g. sand dune, braided rivers, geothermal)
• Trophic levels


  • Producers (plants which produce biomass during photosynthesis)
  • Consumers (organisms that cannot produce nutrients or energy and obtain them by feeding on other organisms)
  • Decomposers (bacteria and fungi, detritivores that release nutrients from remains of plants and animals for reuse by primary producers)
• Food chain


  Sequence of organisms which provide a source of nutrients for the next
• Food web


  Interconnected food chains, organisms feed on more than one type of organism
• If an aspect is removed from the food web it falls apart e.g removal of snapper leading to kina barrens in Hauraki Gulf
• Ecological niche


  The specific position occupied by an organism in an ecosystem, including the physical environment and role it plays in the wider ecosystem
• Benefits of biodiversity


  • More resilient alternative food sources
  • More tolerable with climate change
  • Medicines from natural products
  • Aesthetic and cultural benefits
• Ecosystem services


  • Food, materials and natural products for medicine
  • Water purification and regulation
  • Pollination
  • Erosion regulation
  • Functions that support life such as cycling of nutrients and production of oxygen
• Types of diversity


  • Ecological diversity
  • Species diversity
  • Genetic diversity
  • Functional diversity
• Threats to biodiversity (HIPPO)

  • Habitat destruction (draining of wetland, coral bleaching, deforestation for agriculture)
  • Invasive species (e.g. Aussie brush tail possum, rats and mice)
  • Pollution (fertiliser and road run off, effluents)
  • Population growth and consumption patterns
  • Overharvesting (seals, fish)
• New Zealand has significant biodiversity and unique ecosystems. There are a range of interlinked concepts within this, such as trophic levels, food chains and webs, ecological niches and subsequent ecosystem services. However, if one aspect is impacted, they are all effected. Increasingly biodiversity is under threats, mainly from human activity.
• Soil


  The life supporting skin which humanity relies on for food production
• Soil


  • Formed by the weathering and breakdown of minerals by chemical processes
  • Formed by the decomposition of plant matter
• Benefits of soil


  • Treats water and waste by acting as a filter
  • Supplies nutrients to plants
  • Acts as a sink for some contaminants
  • Source of food, fibre and energy
• Soils in NZ


  Younger than other countries, formed from volcanic activity and tend to be more acidic, more soil amendments needed to get suitable pH and ultimate production
• Plants in NZ are slow growing and low in nutrition, thus many are imported e.g. clover, rye grass, as farmed animal protein is also based on introduced animals
• Nutrients in NZ soils

  Generally low, initially brought from seabirds and ash and soil matter from land clearance, quickly depleted, need inputs to receive outputs (harvesting of food)
• Fertilizers used


  • Organic fertilisers: fish meal, animal effluent and compost
  • Nitrogenous fertilisers: produced from ammonia, made by the Haber-Bosch process
  • Phosphorus: accumulated excrement of seabirds, rock phosphate imported from Asia, Pacific and Africa
• Clover and ryegrass pasture

  Traditional mix, captured nitrogen from the atmosphere, and supported farming, however been impacted by invasive species
• Phosphorus can accumulate in soils


  Nitrogen can contaminate surface and groundwater
• Nitrate is water soluble and can easily leach into groundwater, can reach toxic concentrations and cause blue baby syndrome in infants
• Eutrophication - freshwater becomes enriched in nutrients resulting in excess algal growth, prevents light from entering the water, uses up the oxygen and organisms and fish die
• Greenhouse gas emissions - nitrous oxide (potent greenhouse gas and NZ's largest contributor) is produced in soil by bacteria
• Regulatory controls


  • Under RMA, changes being made in regional plans to protect groundwater and surface water, e.g. Manawatu one plan, which enforces a maximum value of nitrogen leaching on farms, based on the land use and its capability
• Reducing nutrient inputs


  • Only using enough nutrients to meet plant requirements
  • Ensuring they are applied at the right time
  • Adjusting fertiliser inputs