This past week, we took a trip to Ocracoke for an overnight retreat. One of the things that we did while on our retreat was tour Portsmouth Island, an abandoned settlement across Ocracoke Inlet. The town was primarily a fishing village and had a peak population of approximately 680 but a combination of economic and environmental hardships steadily forced people off the island. The last residents left the island in 1971 and since then the island has been a historic site with some standing building for tourists, OBXers, and ex-Portsmouth residents to visit.
The island is home to a very prominent maritime forest as well and within the forest, there are lichens carpeting the ground. To be honest, I barely knew what lichens were when we got to the island but I was intrigued by them when I saw them. Therefore, I decided to look into their ecology so that I could better understand their value to ecosystems.
At first glance, I think most can recognize that lichens are a sort of fungus and that is partly true. Lichens are actually a symbiotic relationship between fungi and algae or in some cases, cyanobacteria, and are an important part of the biological soil crust (Ahmadjian, 2017). In the relationship, the algae or cyanobacteria photosynthesizes while the fungi works in the acquisition of water and nutrients (Luecking, 2016). They are found across all terrestrial habitats and can also be found in aquatic and marine habitats. Lichens are known for being able to thrive in the harshest of regions, such as boreal forests, on any kind of inanimate object and play a large role in the wellbeing of these ecosystems (Ahmadjian, 2017). Much of the research that has been done on lichens has been on the European and North American continents and so there is still a lot unknown about the ecology of lichens (Will-Wolf, 2006). Although, studies do theorize that there are a similar number of species in all kinds of regions (Luecking, 2016) It is known that they offer significant habitat and food for invertebrates and small vertebrates in harsh ecosystems too (Zedda and Rambold, 2015).
Furthermore, lichens have ecological value as bioindicators and biomonitors of pollution and air quality (Jovan, 2008). Studies show that lichens are very sensitive to air pollution and so many people have begun using them as a way to monitor for specific pollutants and overall air quality. The presence of lichens on Portsmouth could point to this trait of lichens since the island is largely cut off from human disturbances. Lichens have also been found to be a cheaper way to monitor air quality than most conventional methods (Luecking, 2016). Lastly, since lichens are so sensitive to environmental change and anthropogenic impacts, they have been cited as a good indicator of climate change (Aptroot, 2009).
At face value, lichens seemed to be just an aesthetically pleasing part of the ecosystem on Portsmouth Island. But after some research, it is clear to me that they play a much larger role within the island’s maritime forest and the global ecosystems.
Ahmadjian, Vernon. (2017). Lichens. In AccessScience. McGraw-Hill Education. https://doi-org.libproxy.lib.unc.edu/10.1036/1097-8542.380500
Aptroot, A. (2009). Lichens as an indicator of climate and global change. In Climate change: Observed impacts on Planet Earth. Edited by T. M. Letcher, 401–408. Amsterdam, The Netherlands: Elsevier B.V
Jovan, S. (2008). Lichen bioindication of biodiversity, air quality, and climate: baseline results from monitoring in Washington, Oregon, and California. Portland, OR: U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station.
Luecking R., Will-Wolf S. (2016). Lichen Ecology. Oxford Bibliographies on Ecology. Oxford University Press.
Will-Wolf, S., L. H. Geiser, P. Neitlich, and A. Reis. (2006). Comparison of lichen community composition with environmental variables at regional and subregional geographic scales. In Journal of Vegetation Science.
Zedda L., Rambold G. (2015) The Diversity of Lichenised Fungi: Ecosystem Functions and Ecosystem Services. In: Upreti D., Divakar P., Shukla V., Bajpai R. (eds) Recent Advances in Lichenology. Springer, New Delhi