Hues of green accented by flowers of red and orange, Le Selva Biological Station is a striking exchange from the prairie land to which I am accustom. Lush vegetation flourishes along established trails throughout the site leaving this Iowan overwhelmed by the diversity.
The Holdridge Arboretum stands alone in its vacant understory. The 3.5 hectares are maintained by regular mowing and cutting to facilitate study of the 240 native species cultivated there. Lack of a vibrant understory is not to say there is a lack of diversity in the arboretum. The easy access to trees promoted my fascination for a most peculiar organism. Lichens.
“Is this fungus or algae”? The tropical plant guide I purchased in preparation for my escapade through the rainforest did not address this strange arrangement of filamentous growth on nearly every surface and substrate. Lichens were a topic glossed over in my years as an undergraduate studding botany and ecology. I understood that a lichen was a symbiotic association of photosynthetic material housed in a thallus provided by a fungus but I was unaware of the diversity and abundance that would belong to the tropical rain forests of Costa Rica.
Taking many shapes and forms, lichens have captured my attention not only for their multiplicity but also for their ambiguity; what may appear to be a single lichen by the light of day may be revealed as several different species by their fluorescence under a UV light. Providing similar ecological roles of a fungus as well as harvesting the photosynthetic power of algae and cyanobacteria, lichens play important indicators of forest health and succession. Because the abundance of lichen species is largely unknown, they may provide imperative value to the ecosystems they inhabit and potentially offer unknown services to humans. Here in lies my unexpected interest.