Module 5 (19-21)- NZ'S Geological Biological & Human History

• Gondwana


  • One of the 2 supercontinents that split from Pangea, which had split into Gondwana and Zelandia.

  • Zelandia then split eastward from Australia, forming NZ
• Zealandia


  • A lost continent that existed around 180 million years ago and is now submerged beneath the Pacific Ocean east of New Zealand.

  • The continental crust of Zelandia is mostly too thin to project above sea-level

  • In the north the pacific plate goes under the Australian plate in the south, the Australian plate goes under the pacific plate sea level
• Recall the Role that plate shifting has in creating landscapes in Aoeteroa

  • Most of Aoeteroa was almost fully submerged under water during the Oligocene epoch (33.9 to 23.03 Ma)
  • NZ formed at the junction of the Australian and pacific plates
  • The continental crust of Zealandia is mostly too thin to project above sea level
  • In the north the pacific plate goes under the Australian plate in the south, the Australian plate goes under the pacific plate
  • Evidence of this is the abundance of limestone (marine sediment) around NZ, as well as the shell fish fossilized further inland
• New Zealand is part of the Indo-Australian Plate which was once joined with India as part of the ancient supercontinent of Gondwana
• During the collision, some parts of the Earth’s crust were pushed up while others were forced down, resulting in the formation of mountain ranges like the Himalayas.
• Explain how the mountains in NZ formed

  • Uplift + Errosion -> sedimentary depositions
  • Uplift from tectonic plates colliding, pressure acts which forced mountains to erupt
  • Volcanic activity: lake Taupo, Rangitoto, Mt Wellington etc
• Explain how sea level changes have affected the exposed area of Aotearoa

  • Water stored in glaciers and ice sheets
  • When climate, war, release of water from ice sheets raise global sea levels
  • 3 mya melting of the Antarctic ice sheet increased sea levels around NZ
  • The Pleistocene ice age caused repeated changes in the sea levels over the past million years
  • 20,000 years ago, sea levels were 100m lower reaching the edge of the continental shelf
  • Glaciers were exposed in southern NZ
• Outline important post-Pleistocene changes in the Aoeteroa environment

  • These allowed NZ forests and land mass to reach the capacity they have today
  • Vegetation patterns also changed over time as climates changed

  
• ARCHAIC PERIOD



  1300-1500:
• CLASSIC PERIOD


  1500-1642
• What are the potential explanations for NZ flora and fauna?

  1. Continental drift, that organisms are only just carried over from Australia when we split
  2. Land bridges, island hopping from the Zealandia islands eg birds
  3. Transoceanic dispersal ie flying/floating
• Gondwanian Fauna


  Fauna that originated from the ancient supercontinent of Gondwana
• Peripatus 'velvet worms'


  • Less likely to migrate to NZ after the formation of an ocean
• Reptiles in NZ


  • Dinosaurs
  • Pterosaur
  • Tuatara
  • Skink
• Amphibians in NZ


  • Leiopelmstid
  • Frogs
• Turtles have not yet been discovered in NZ
• Moa were assumed to be Gondwanan but are now known to be related to the flying Tinamous of South America
• Kiwi are now known to be related to the elephant bird of Madagascar
• While the ratite group is Gondwanan, their origins are more recent
• Birds are another potential 'true' Gondwanan fauna
• Birds are the most basal passerine (perching birds in radiation) but are too recent in lineage
• Much of the NZ bird fauna has arrived comparatively recently and it is hard to prove deep origins
• NZ pre-human Fauna 


  • Fresh water life

  > Fresh water fish, koura, shellfish, fresh water mussels

  • Marine life

  > Fishes and other marine organisms

  > Marine animals: Whales and dolphins, sea lions, fur seals

  • Land mammals

  > Bats (3 species)

  • Reptiles

  > Tuatara

  > Skinks an geckos (>100 species)

  • Birds: 245 species in greater NZ region

  > Apterygiformes: Kiwi (5 spieces)

  > Dinornithiformes: Moa (9 species)
• Endemic species


  • Apterygiformes

  > Kiwis (5 pieces)

  • Dinornithiformes

  >Moa (9 pieces)

  *Unique features

  >Big and flightless
• Pre-human NZ


  >Colonial birds and mammals

  >Nativity - species had never encountered humans

  
  

  • Migrating birds would have indicated the presence of land in the South Pacific
• What evidence is there from when humans colonized NZ?

  • Sea-faring Polynesians reached NZ by the late 13th century, bringing Pacific rats, dogs and fire.
  • We can approximate the date of their arrival by:

  >Dating charcoal from forest burning

  >Dating rat-knawed seeds that were brought with the colonizers as a food source

  • Both sources indicate Aoetearoa's colonisation to about 1280 AD

  
• What happened in the Archaic period (1300-1500) of Moari Occupation?


  • Otago region major area of Maori development
  • Small settlements within 10km of the coast
  • Was common for people to establish small temporary camps further inland for hunting
  • Settlements ranged in size from 40 people to between 300 and 400 people

  * The Archaic period is remarkable for the lack of weapons and fortifications during this time, signifying peace between the settlements
• What happened in the Classic period (1500-1642) of the Maori Occupation?

  • Colder climate
  • Earthquakes in the southern alps and Wellington region
  • Tsunamis
  • Loss of food resources
  • Associated changes in settlements, such as fortified pā and culture
• What impacts did the Maori settlers on NZ?

  The Pacific rat, fire, forest loss, hunting and at the end of the initial Maori phase, 13th to 15th century, rat and human predation had decimated populations of terrestrial birds, mammal colonies, reptiles and large insects

  • The fire was a deliberate tool to open up the countryside and convert the forest into a more 'useful' fern habitat with tubers
• Māori occupation in Aotearoa

  • Sites at low and middle elevations and dry sites showed conversion from closed forest to tussock grasslands and fern-shrubland and little subsequent recovery
  • Higher-elevation wet watersheds were less affected and may have had some forest recovery during the Late Māori period
  • The fire activity was lower if distant from travelways or surrounded by natural fire breaks
  • Drier, lower-elevation sites with larger and more permanent human settlements had persistent fires from the onset of Māori arrival to the present
• Fires initiated


  Forest destruction, slope instability, and erosion
• The import of sediments and nutrients evoked a response in the lake chemistry and limnobiota
• What food sources were used by the Maori?

  • They switch from a carbohydrate-rich diet in the Pacific (kumara, breadfruit and bananas) to a protein-rich diet in Aotearoa

  >Could grow kumara where warm

  >Fern root - dig up, dry, roast, grind

  >Stems and tap-roots of young cabbage trees and

  tree ferns cooked in an umu

  > Poisonous fruits need careful preparation

  *Analysis of the DNA on the food scraps left behind, give an indication of what food sources were used by the māori
• What impact did Māori settlers have on wildlife?

  Birds

  • Huge and immediate on large-bodied and flightless birds
  • Most famous example: Moa
  • 12-250 kg in size
  • Estimated >1 million moa in NZ before humans
  • Hunting only lasted 150 years; moa estimated to be extinct within 200 years
  • Loss of moa= loss of food supply for Haast's eagle
  • Kiore (pacific rat) were a valued food source for the Maori, but are also the reason several small bird and frog spices went extinct
• What happened in the human occupation period of 1280-1642 (Maori Settlement)


  • Extensive changes to the landscape through forest fires
  • Loss of 6.7 million hectares of forest
  • Loss of the terrestrial megafauna and ground-dwelling birdlife (38 species)
  • This necessitated the development of different and more sustainable ways of living in the post- archaic period
• What is the timeline of European Arrival?

  Abel Tasman: 1642 (didn't land)

  James Cool: 1769

  Late 1700s onwards: Regularly visited, settled extensively in 1800s
• What were the direct effects of European Settlers?

  • Forest destruction to make way for farms 1840s onwards
  • Between 1840 and 2000 another 8 million hectares were cleared
  • 90% loss of wetlands for farming since European arrival
  • Initial demands for NZ specimens like bird skin in Europe were too high
• What were some indirect effects of European settlers?

  • The introduction of predatory mammals is a huge impact , virtually 16 species extinct due to predation
• Compare the Moari settlement to the European settlement

  • Māori colonisation of Aotearoa in about 1280 was followed by a wave of habitat change and species loss, principally of food species but also through predation by kiore.
  • European colonisation resulted in a second wave of habitat destruction and the introduction of a suite of mammalian predators that have wreaked havoc on the New Zealand wildlife
• What is Matauranga Maori?

  • The combination of polynesian ancestors and the experiences of Maori living in the environment of Aoeteroa
  • Mātauranga Māori is increasingly recognised as being a critical part of our understanding and management of New Zealand’s environment and wildlife, both natural and exotic