Zones of Galapagos

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Zones of Galapagos
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Distribution and Size of Islands

• The islands are heterogeneous in 3 features that
  are important to biota
• area of island
• elevation
• isolation
• Not all islands are entirely vegetated

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Vegetation

• Zones are a function of precipitation and
  temperature
• Predominant vegetation is dry, mainly deciduous
  forest at low elevations
• Transitional forest and moist forest at high
  elevations
• Grassy habitat at the highest elevations on a few
  islands

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Vegetation Zones

• Seven zones are distinguished but only big
  islands like Santa Cruz and San Cristobal have
  them all
• 1. Coastal or Littoral Zone
• 2. Arid Zone
• 3. Transition Zone
• 4. Scalesia Zone
• 5. Brown Zone (sometimes left out)
• 6. Miconia Zone
• 7. Pampa or Fern Zone

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Page 134 Fitter
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Littoral/Coastal Zone
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Littoral or Coastal Zone (p142-148 Fitter)

• Very narrow stretch a few meters wide found on
  coast or around lagoons
• Vegetation influenced by salt and is made of
  shrubs and small trees
• Mangroves are dominant. The word mangrove is an
  ecological term rather than a classification
  since four species come from different families

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• Salt bush-provides shade for sea lions, pelicans
  and frigate birds
• Carpetweed, an herb, Sesuvium spp.
• This zone is a habitat rich in invertebrates,
  molluscs, crustaceans and insects

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Arid Zone
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Arid Zone (p 150-182 Fitter)

• Spreads up to an elevation of 80-120 meters
• Dominant vegetation are 3 endemic cacti
• Opuntia- tree-like prickly pear 5-6 feet tall
• Jasminocereus-candlebra cactus 23 feet tall
• Lava cactus-small cactus 23 inches tall
• Palo Santo tree is characteristic of this zone

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• Important zone because a high proportion of
  endemic plants have evolved under the harsh
  conditions of this zone with little moisture
• Plants have a xerophytic adaptatin
• small leaves, high rate of photosynthesis, spiny
  shrubs, deep roots
• Reptiles like land iguanas, lava lizards, and
  snakes are at home here
• Finches, warblers appear where vegetation is
• Lichens are found here too

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Transition Zone
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Transition Zone (p150-182 Fitter)

• Zone climbs between 100-200 meters
• Palo Santo trees are found here too
• This zone is more dense and less desert-like in
  appearance
• Pega pega (stick stick)-tree with short stem and
  spread out branches
• Guayabillo-white flowers and small fruit
• Galapagos tomato plant found here

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Scalesia Zone
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Scalesia Zone (p178-180 Fitter)

• From 200-400 meters
• First of the humid zones
• Where garua concentrates during dry season
• Ferns, grasses and mosses are abundant
• Predominant species is Scalesia (broccoli) tree
  can be 10 meters tall

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• Scalesia forests have been reduced by
  human-related activities
• pigs and goats root out seedlings
• land was cleared for planting or grazing
• fires
• Guava plant has infiltrated all the highlands
  their dense growth squeezes out other plants in
  area

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Brown/Zanthoxylumzone
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Brown Zone (p178-180 Fitter)

• Ends with scalesia zone
• Liverworts are characteristic plants-cling to
  scalesia but do not depend on it
• These brown mosses fall from the branches of the
  scalesia

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Miconia Zone
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Miconia Zone (p178-180 Fitter)

• Humid zone at about 600-700 meters
• Endemic to Galapagos
• Most endangered plant in Galapagos
• Only found on Santa Cruz and San Cristobal

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Pampa or Fern Zone
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Pampa or Fern Zone (p 198-199 Fitter)

• Ranges from 650 meters up to the summit of the
  island
• Wettest zone in islands
• Dominant plant is endemic Galapagos tree fern
  (tall as an adult)
• Is represented by ferns, grasses and other plants
  adapted to water
• Moist pampa is a microclimate in itself