TOPIC 7 LichenS of Costa Rica

That is why it is difficult to define what they are; however, there is a clear definition of this type of living being. Lichens are a self-sustaining association between a fungus and an algae and/or cyanobacterium. In lichens, the algae or cyanobacteria (scientifically called photobiont or phycobiont) is the energy producer, which through photosynthesis produces sugars and oxygen. On the other hand, the algae benefits from the fungus (mycobiont), because it protects it from adverse environmental conditions, such as loss of moisture, and provides it with the carbon dioxide that is produced in respiration. The necessary minerals generally come from atmospheric dust, rainwater and what the fungus can absorb from the substrate. Lichens can live in many different habitats, for example; páramo, tropical cloud forest, tropical rainforest and tropical dry forest. As commented before, lichens are included in the Fungi Kingdom, since for their identification and taxonomic classification the fruiting body of the fungus is taken into account, which is a structure formed by the fungi where the spores that come to be are produced like seeds in plants. The fruiting bodies have a great variety of shapes and colors. (Umaña, s.f, paragraph 6).

L I C H E N S O F C O S T A R I C A

L i c h e n s a r e n o t m o s s e s n o r a r e t h e y p l a n t s a s i s p o p u l a r l y b e l i e v e d . T h e y a r e o r g a n i s m s t h a t a r e c l a s s i f i e d i n t h e K i n g d o m o f F u n g i , a n d t h e y a l s o h a v e a g r e a t v a r i e t y o f s h a p e s a n d c o l o r s t h a t a l l o w s t h e m t o l i v e i n a g r e a t v a r i e t y o f s u b s t r a t e s a n d p l a c e s . ( U m a ñ a , s . f , p a r a g r a p h 3 ) .

This amazing group has a very interesting morphology, just with their external appearance can be distinguished in three large groups that are the following: crustacean lichens, foliose lichens and fruit lichens. Crustacean lichens (have a crust shape); they live intimately united to the substrate, for example, on the surface of rocks or crust like the species of the genus Graphis sp. Sometimes they penetrate the substrate and their growth is very slow, a few millimeters per year. . (Umaña, s.f, paragraph 8)

Foliose lichens (they are similar to leaves); They have a flattened and lobed shape, they are fixed to the substrate by means of special structures called rhizines, for example, the genera Sticta and Peltigera. Fruticulosus lichens (they have a bushy shape); they are attached to the substrate by a very narrow base (for example, Cladonia didyma). These are fast growing forms (up to 1-2 cm per year). Many lichens do not fit neatly into one of the above growth forms; as is the case of gelatinous lichens, with a high capacity to store water. Other growth forms are generally small lobes. Some have vertically elongated fruiting bodies. Many species of Coenogonium, a fairly common genus in humid tropical rainforests, have a filamentous shape. (Umaña, s.f, paragraph 11).

WHERE CAN WE FIND THEM?

They are distributed worldwide, from the polar circles to the desert areas, and from the sea coasts to the jungles and humid forests. Several factors affect its distribution; water, temperature, light and the diversity of substrates. They can grow on a wide variety of substrates (trees, fallen logs, rocks, mosses, soil, leaves, even on plastics and metals). Those that live in humid forests are generally on leaves or on the bark of trees, while those that live in dry or cold areas are generally terrestrial or grow on rocks.

They are distributed worldwide, from the polar circles to the desert areas, and from the sea coasts to the jungles and humid forests. Several factors affect its distribution; water, temperature, light and the diversity of substrates. They can grow on a wide variety of substrates (trees, fallen logs, rocks, mosses, soil, leaves, even on plastics and metals). Those that live in humid forests are generally on leaves or on the bark of trees, while those that live in dry or cold areas are generally terrestrial or grow on rocks.

Applications

Some lichens have nutritional and medicinal properties, as well they are used as indicators of the health of the environment. (Umaña, s.f, paragraph 14). For instance, in Japan, foliose lichens that are known as iwatake, are eaten in salads or fried. Moreover, in medicine they are used in antitumor, antifungal, antiinflammatory and also antibiotic drugs. In addition, they are used in the measurement of air quality, since they can live for many years and are sensitive to polluted air. They have also been used in architecture, colorants, perfumes, and cosmetics.

F U N C T I O N I N N A T U R E

Lichens containing cyanophytes fix nitrogen from the atmosphere and provide it to the soil, forming part of the nitrogen cycle in ecosystems. As a result, they have been used to provide an initial substrate for the development of new seedlings; furthermore, to provide a habitat for a number of animals that take refuge in them. Also, they are important as food in animals, for example, the Norway mouse feeds on some species of the genus Usnea, the caribou of the genus Cladonia, while sheep in Libya feed on foliose lichens. Likewise, lichens are food and shelter for a large number of invertebrates, including psocoptera (book lice), mites and moth larvae. And they play a very important role in the photosynthesis process, many lichens grow epiphytic on trees and shrubs and contribute to the water and nutrient cycle of ecosystems. Lichens containing cyanophytes (blue-green algae) fix nitrogen from the atmosphere and incorporate it into the soil. (Umaña, s.f, paragraph 18).