Galapagos Flora—Notes from a Trip

The Galapagos Islands are located in the Pacific Ocean about 620 miles off the coast of Ecuador. Located in the Pacific dry belt, the volcanic archipelago and marine reserve consists of 3,000 square terrestrial miles and 52,000 square marine miles. The land area is 97 percent national park.

The archipelago is located at the confluence of the cool Humboldt Current from the south, the warm Panama Current from the North and the upwelling Cromwell Current just west of the islands. These currents bring together a unique variety of marine species and influence the climate.

The Galapagos are continuously changing because of their volcanic past and present. The archipelago was formed by volcanic activity. Most of the islands contain the summit of one or more volcanos, some of which are active.

Natural processes plus the extreme isolation of the islands led to the unusual animal life that inspired Darwin’s theory of evolution by natural selection, published after he visited the Galapagos in 1835.

Listed by UNESCO as a world heritage site, the 19 islands and surrounding marine reserve provide a laboratory for scientists. The Galapagos have been called a “living museum and showcase of evolution.”

There are three major vegetation zones: coastal, arid and humid highlands.

The coastal zone is populated by plants that tolerate salty conditions. Mangroves are perhaps the most common plants found along the coast. They provide a breeding site for fish and birds, shade for sea lions and protection for sea turtles.

The arid zone is the most widespread. Plants include species adapted to drought-like conditions—cacti, succulents and leafless shrubs that grow foliage and flower only during the rainy season. Prickly Pear cactus and purslane are immediately recognizable in the mix.

The humid zone is lush with green forests of endemic Scalesia trees, hung with mosses (similar to Spanish moss), liverworts and epiphytes. Only larger islands are high enough to support this vegetation.

There are180 endemic plant species on the Galapagos.

Mangroves are not endemic but native; their seeds floated to the islands from the mainland. Their seeds fall from a tree into the water. Using photosynthesis they can survive floating for weeks. Ocean currents take seeds eventually to their ideal environment of brackish water where buoyant water raises the top half of the seed while the bottom half embeds itself in new ground. Native vegetation on the islands arrived as twigs and seeds floated in and propagated in a similar manner.

The endemic Scalesia, aka daisy tree, populates the high humid altitudes of the large islands. Wind originally carried the seeds to higher elevations where, with no competition, they were able to grow and thrive. Their height allows them to take in moisture from the air. Understory vegetation uses the moisture from water droplets that fall from leaves or run down the tree trunks. The trees are in the daisy family and have small daisy-like blooms.

About 95% of the islands’ native species remain today largely because they have lived primarily without predation or competition. Unfortunately, though, humans have carried alien species to the islands, intentionally and accidentally. Introduced species include ornamentals, edible and weedy plants; rodents, goats, pigs and insects. They have been able to thrive because they, too, face little predation and competition. However, some of the introduced species are aggressive to the point of displacing natives.

The effort to combat and control invasive and introduced species is ongoing and intensive. Galapagos Inspection and Quarantine System personnel inspect cargo from ships and planes as well as tourists’ luggage and bags for plants, fruits and vegetables. Even shoe treads may be checked for soil before intra island travel. Community education increases local awareness and participation in the battle against introduced species and invasives.

Biological control is used when deemed safe. For example in 2002, the Australian ladybug was brought in to combat cottony cushion scale which threatened more than 60 native and endemic species. Although scale is still obvious on some plants the ladybugs have brought the pest to manageable levels.

Major island restoration programs have been successful in controlling feral livestock that has decimated areas of native plants. Smaller scale programs include eradicating a species of fire ant and controlling an invasive species of blackberry. Carpenter bees and wasps are on the agenda. So is control of fast-growing shrubs like guava, lantana, quinine trees and elephant grass. The newest initiatives focus on full ecosystem restoration.

Furthermore, the animals on Galapagos are astonishing.

This story was originally published July 8, 2016 at 2:16 PM with the headline "Galapagos Flora—Notes from a Trip."