Časopis NOVÁ BOTANIKA

Galápagos - Paradise Still Not Lost

Chapter 1

“Before HMS Beagle entered the archipelago in 1835, most newcomers considered these islands a kind of God-forsaken hell on earth. Feelings have changed since then, and now the archipelago is widely considered the closest to the original picture of paradise.”
H. Nicholls (2014): The Galápagos. A Natural History

General information

The official name is Las Islas Galápagos or Archipiélago de Colón [Columbus Archipelago]. Everyone thinks that it is very far, but the islands are not at all at the antipodes, but only slightly more than half the way to them: from Prague in a straight line to the local main Baltra airport is just over 11,000 km, so even a bit closer than to the island of Bali in Indonesia, which the “average traveler” has the opportunity and chance to visit with a much greater probability.

In total, 61 islands and islets (13 larger islands, six smaller islands and 42 islets) are named in the entire Galápagos archipelago, but only four of them are inhabited (Santa Cruz, San Cristóbal, Isabela, and Floreana). The islands are located in the Pacific Ocean, about 930 km west of Ecuador, to which they administratively belong. Due to this location, four sea currents are important in shaping the climate of the islands (Figure 1): the South Equatorial Current that flows from east to west, the weaker Panama Current directed from the north-east to the south-west; in addition, there is the South Equatorial Countercurrent (= the so-called Cromwell Current) directed from west to east, and the Humboldt Current (Peru Costal Current), directed from the south-east to the northwest, along the coast of Peru.

The latter is a strong and cool current, and its impact on the islands increases from June to November. Then the temperature drops on the islands and the moisture in the cooler air condenses in the form of a mist (so-called garúa) (Figure 2). The appearance and occurrence of garúa fog is particularly beneficial for most spore plants, especially ferns and bryophytes, mainly because the sexual reproduction of these organisms depends on the presence of water. The epiphytic mosses that occur in large numbers on the trees are soaked with moisture that, especially during this period, one can observe continuous drops of water dripping from them (Figure 3). In this way, the substrate of the supporting trees and shrubs is irrigated with a particularly high efficiency. However, in December, the Humboldt Current weakens and begins to overwhelm the Panama Current, coming from the northeast. This current is weaker but warmer. It causes the mist (garúa) to evaporate and the heat season begins again. However, as the water temperature increases, evaporation increases, clouds form, and rain falls again...

Ecological zones

There are three basic vegetation zones on the Galápagos islands:
- coastal zone, distinguished primarily by salinity, which has a significant impact on the floristic composition,
- a dry or very dry zone that we will try to recognize today,
- highlands irrigated in the cool season by garúa and in the hot season by rains, with much more lush vegetation; it is well known that plants can go almost anywhere with the help of wind and birds, so there is a great vertical plant variation in the Galápagos. In the cold season (from June to November), at an altitude of 500 to 1000 m above sea level, the garúa rises and thus a zone of lush, moisture-loving vegetation with rich flora develops;
- higher, on the slopes covered with clouds, there is a lush, steamy/misty upland rain forest with Scalesia sp. (Figure 4). They are trees from the Asteraceae family, which is unique in itself, because in Europe, although we have the largest number of species belonging to the Asteraceae family, they are all herbaceous; the closest woody examples of species from this family could be found in the Canary Islands, but this is Africa after all!.

Bartolomé island and its endemic plant species

So we are in Galápagos now and today we are going on the most popular trip in the entire archipelago, to the island of Bartolomé, to admire the scenery and take the most famous photo, visible on most of the postcards from these islands (Figure 5 above). Bartolomé is a small, rocky, uninhabited volcanic island. Its name commemorates the British sailor Sir Bartholomew James Sulivan, a member of the HMS Beagle expedition, on which Charles Darwin sailed to Galápagos at the end of 1835, and his discoveries during this voyage formed the basis of the theory of evolution, thanks to which this ship became one of the most famous in history. Even diving is allowed around the coast of Bartolomé. The most characteristic feature of the island is the Pinnacle rock, formed by solidified lava, cooled immediately after its eruption by seawater (Figure 5 and cover picture). The time spent on Bartolomé should not be excessively long, usually no more than 2 hours, to protect the ecosystem and minimize human pressure.

Before we get to know some of the characteristic plant species of the dry zone, it should be noted that most of the flowering plants on the Galápagos are capable of self-pollination (!), and at the same time, due to the lack of the need to attract insects, their flowers are usually not particularly visually striking. Therefore, white or yellow flowers are usually found among typical indigenous species.

On the raw volcanic substrate of the Santiago and Bartolomé islands, you can meet, among others several local plant endemics. The first is Tiquilia nesiotica (from the Boraginaceae family, which cannot be hidden, even by looking at its leaves, which are heavily hairy, which is a characteristic feature of most species belonging to this family; Figure 6, 7). This plant species is endangered with extinction (VU category; VU means Vulnerable in English). Tiquilia nesiotica is one of the first species that inhabits the bare soil of a volcanic nature - such plants that appear in various previously uninhabited habitats are called pioneer species/organisms. And it is exactly on the island of Bartolomé, as far as the eye can see, a very harsh landscape, poor in plant species can be found. The ones that showed up here are pioneer species. Tiquilia nesiotica forms characteristic, gray, sometimes quite compact clusters, hence its English name: gray matplant. Its flowers are small, inconspicuous, cream-colored, and inside a bit cherry red.

Another endemic plant to the Galápagos Islands and at the same time also a pioneer species inhabiting naked, frozen lava is Mollugo flavescens from a separate family Molluginaceae (Figure 8, 9). The scientific name of this genus given by Linnaeus was derived from the species name of hedge bedstraw (Galium mollugo), very well known from the moderately moist meadows of central Europe, possibly due to the similarity of the leaves that grow in the whorls (Figure 10). The shoots of Mollugo flavescens from Galápagos are heavily glanded (covered with glandular hairs) and are mostly red-brown in color; the flowers of this plant are also relatively inconspicuous, light pink, and white in color. Other members of the Molluginaceae family are more widely distributed: they occur on all continents in areas in tropical and warm temperate climates (also in the Balkans and vast areas of North America), and some species of this family are used in traditional folk medicine in South Asia and in Africa.

Under the same type of pioneering conditions, various species of succulents are also found in the frozen lava of the Galápagos archipelago. Among other plants, the endemic Brachycereus nesioticus (family Cactaceae; Figure 11), which has the ability - as one of the first species - to settle in streams of freshly solidified lava, then creating dense clusters on it. It can be found especially in the dry parts of the Galápagos Islands and later usually among vegetation in open spaces. In addition to the island of Bartolomé, it is also found, for example, on the coast of Sullivan Bay (on the neighboring island of Santiago), in Punta Moreno (on the island of Isabela), and on the island of Genovesa. This cactus grows very slowly and rarely blooms, and pollination is possible for only a few hours. Its flowers are single, white to yellowish-white inside, up to 11 cm long and 5.5 cm wide, with numerous thorns on their lower parts. After flowering, the withered remnants of the perianth (calyx and corolla) and the dried stamens remain on the fruit, covered with yellow thorns; the fruit contains numerous black seeds inside.

Needless to say, iguanas, snakes, scorpions and geckos, as well as many species of birds, are eager to live in such a thorn-protected habitat.

Figure captions

Figure 1. The most important role in the climate of Galápagos islands have ocean currents.

Figure 2. In fact, all ferns love moisture in the air. We can check it at our homes: our ferns grow much better when sprayed with water than those exposed to dry air. It is no different in the Galápagos Islands: in the foreground, you can see numerous ferns on the edge of the Los Gemelos collapsed craters on Santa Cruz Island. In the background: the interior of one of these collapsed craters is shrouded in fog, here called garúa.

Figure 3. Epiphytic mosses that occur on trees, in the period from June to November are all soaked with moisture that, especially during this period, you can see drops of water dripping down from them.

Figure 4. Higher elevations of Gálapagos islands are covered by rain forest with Scalesia sp. trees from the Asteraceae family.

Figure 5 and cover picture. To take the most famous photo featured on most Galápagos postcards, head to Bartolomé Island. The most iconic point of the island is Pinnacle Rock, formed by solidified lava, cooled immediately after its eruption by seawater.

Figures 6 and 7. Tiquilia nesiotica is a species from the borage family (Boraginaceae) with relatively inconspicuous flowers, a pioneering plant that inhabits as one of the first previously uninhabited substrates, in this case volcanic in nature. It is endemic to the Galápagos Islands.

Figures 8 and 9. Mollugo flavescens is a plant that belongs to a separate family of Molluginaceae. It is another species of endemic pioneer plant that inhabits naked frozen lava in the Galápagos archipelago.

Figure 10. Foliage of hedge bedstraw (Galium mollugo), a common plant in medium-humid meadows in Central Europe, belonging to the coffee family (Rubiaceae). The name of the Molluginaceae family comes from the Latin species name of this plant, which includes Mollugo flavescens, the endemic of the Galápagos archipelago, which inhabits frozen lava on many of its islands.

Figure 11. Brachycereus nesioticus is a representative of the cactus family (Cactaceae), having the ability to settle on streams of freshly solidified lava, and then creating dense clusters on it. The name of the species “nesioticus” comes from ancient Greek and means “insular” or “of the islands”. This cactus grows very slowly and rarely blooms, and its pollination is only possible for a few hours.
K dalšímu čtení:

Author:
Dr hab. prof. Jarosław Proćków
Department of Plant Biology, Institute of Environmental Biology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland

Photograph credits: (cover picture, 2-3, 5-9, 11) Jarosław Proćków; (1) John M. Fitz, University of Maryland; (4) helovi, iStock; (10) Krümelomat, WikiMedia

Explore wonderful plant kingdom

with magazine New Botany

O nás

O časopise

Předplatné