Article & Photography by: R Hnatuik
Lichens are intriguing organisms that have captivated scientists and nature enthusiasts with their unique characteristics. In this article, we will explore the remarkable features and ecological significance of lichens, with a particular focus on their growth and colonization on rocks. This article focuses on their general features and those that grow on rocks.
Understanding Lichens
Lichens are unique symbiotic organisms composed of a partnership between fungi and photosynthetic partners, typically algae or cyanobacteria (Brodo et al., 2001). This remarkable collaboration enables lichens to survive and thrive in a wide variety of environments, including on rocks and soil, on bark or leaves, on logs, buildings, shade cloths and fence posts.
Structure and Growth
Lichens possess a distinct body structure consisting of fungal filaments intertwined with the photosynthetic partners (Nash 2008). This structure allows them to efficiently absorb moisture and nutrients from the environment. Lichens grow slowly, often forming intricate patterns and colourful patches on rocks (McCune and Geiser, 2014).
Lichens on Rocks
Lichens are known for their ability to colonize and grow on rocks. They are often the pioneers on barren surfaces, gradually breaking down the rock's surface through chemical and physical processes (Nash III, 2008). As they grow, lichens create microhabitats that provide suitable conditions for other organisms, contributing to the establishment of a diverse ecosystem,
Ecological Significance
Lichens on rocks play crucial ecological roles. They help in soil formation by gradually weathering rocks and releasing minerals. They trap fine, wind-blown soil particles, thus contributing to the formation of new soil. Lichens also contribute to the retention of moisture, preventing soil erosion and promoting the establishment of other plant species. Additionally, they provide food and shelter for small invertebrates, serving as an important part of the food chain (Nimis et al., 2002). Lichens will often be overgrown by faster growing and taller plants such as mosses.
Conservation and Study
Understanding the ecology and diversity of lichens is vital for their conservation and preservation. Because of their small size and the difficulty in identifying species, they are not often included in endangered species protection programs. Lichens are used as indicators of air quality due to their sensitivity to pollutants. Researchers study lichens to unravel their unique adaptations, their role in nutrient cycling, and their potential applications in various fields, including medicine and bioindicators (Rikkinen, 2002).
Aesthetic Values
The small size and slow growth of lichens means they are not often actively included in garden plans. A few species produce relatively large structures, which can be attractive. At the Arboretum, lichens of the family Parmeliaceae, produce leafy grey-green covering on rocky outcrops. Splashes of colours from orange, brown, white, and black, that look more like splats of paint than an organism, add unexpected experiences for those who look closely. Lichens have contributed colouring dyes to fabrics. As with mosses, lichens are hardy organisms, but can be easily damaged by treading on them.
Conclusion
Lichens are extraordinary organisms that thrive in diverse environments, including on rocks. Their unique symbiotic nature, slow growth, and ecological roles make them a fascinating subject of study for botany students. By appreciating the significance of lichens, we gain a deeper understanding of their ecological contributions and the delicate balance of our natural world.
References:
- Brodo, I.M., Sharnoff, S.D., & Sharnoff, S. (2001). Lichens of North America. Yale University Press.
- McCune, B., & Geiser, L. (2014). Macrolichens of the Pacific Northwest, 2nd ed. Oregon State University Press.
- Lepp, Heino (2014). Lichens and People: Dyeing. Australian National Botanic Gardens and Auastralian National Herbarium. https://www.anbg.gov.au/lichen/lichens-people-dyeing.html [accessed 27 June 2023].
- Nash III, T.H. (2008). Lichen Biology. Cambridge University Press.
- Nimis, P.L., Scheidegger, C., & Wolseley, P.A. (Eds.). (2002). Monitoring with Lichens—Monitoring Lichens. Springer.
- Rikkinen, J. (2002). Diversity and ecology of Antarctic lichens. The Lichenologist, 34(4), 359-374.