Zones of Galapagos

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

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

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

Page 134 Fitter

Littoral/Coastal Zone

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:

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

Arid Zone

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

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 rootsReptiles like land iguanas, lava lizards, and

snakes are at home hereFinches, warblers appear where vegetation isLichens are found here too

Transition Zone

Transition Zone (p150-182 Fitter)

Zone climbs between 100-200 metersPalo Santo trees are found here tooThis zone is more dense and less

desert-like in appearancePega pega (stick stick)-tree with short

stem and spread out branchesGuayabillo-white flowers and small fruitGalapagos tomato plant found here

Scalesia Zone

Scalesia Zone (p178-180 Fitter)

From 200-400 metersFirst of the humid zonesWhere garua concentrates during dry

seasonFerns, grasses and mosses are

abundantPredominant species is Scalesia

(broccoli) tree= can be 10 meters tall

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

Brown/Zanthoxylumzone

Brown Zone (p178-180 Fitter)

Ends with scalesia zoneLiverworts are characteristic plants-

cling to scalesia but do not depend on it

These brown mosses fall from the branches of the scalesia

Miconia Zone

Miconia Zone (p178-180 Fitter)

Humid zone at about 600-700 meters

Endemic to GalapagosMost endangered plant in GalapagosOnly found on Santa Cruz and San

Cristobal

Pampa or Fern Zone

Pampa or Fern Zone (p 198-199 Fitter)

Ranges from 650 meters up to the summit of the island

Wettest zone in islandsDominant plant is endemic Galapagos

tree fern (tall as an adult)Is represented by ferns, grasses and

other plants adapted to waterMoist pampa is a microclimate in itself