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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. 2. 3. 4. 5. 6. 7. Coastal or Littoral Zone Arid Zone Transition Zone Scalesia Zone Brown Zone (sometimes left out) Miconia Zone 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 roots Reptiles like land iguanas, lava lizards, and snakes are at home here Finches, warblers appear where vegetation is Lichens are found here too Transition Zone 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 desertlike 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 Scalesia Zone 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 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/Zanthoxylum zone 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 Miconia Zone 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 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 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