Western Kentucky University
Lichens and Weathering of Kentucky Limestones
Institution
Western Kentucky University
Faculty Advisor/ Mentor
Chris Groves; John Andersland
Abstract
Lichens are complex plantlike organisms showing no differentiation into stem, root, or leaf and are composed of a fungus and alga growing in a symbiotic relationship on a solid surface. While it is well established that lichens are intimately involved in the initial decomposition of rocks by various physical and chemical means, questions remain about conditions under which lichens can accelerate or retard the weathering of the rocks they grow upon. Generally it is believed lichens enhance rock weathering in humid climates and retard weathering processes in arid regions. Limestone composes a large percentage of the surface landscape of Kentucky, and thus the weathering of limestone is of particular importance in understanding the Commonwealth’s landscapes. For this project a variety of lichen species residing on limestone in the Warren County, Kentucky area have been located and identified. While many species of lichens reside in the area, a list was constructed of only endolithic lichens observed and sampled (including foliose species Anaptychia palmulata and crustose species Fuscidea recensa). Samples of limestone with and without lichen cover, and of varying lichen coverings, were collected and analyzed under a scanning electron microscope. Samples of the limestone surfaces directly under the lichen where compared to lichen free surface samples as well as samples of unweathered surfaces. Using this information, detailed descriptions of each particular lichen type’s influence on the weathering of the limestone samples are being developed for each species sampled.
Lichens and Weathering of Kentucky Limestones
Lichens are complex plantlike organisms showing no differentiation into stem, root, or leaf and are composed of a fungus and alga growing in a symbiotic relationship on a solid surface. While it is well established that lichens are intimately involved in the initial decomposition of rocks by various physical and chemical means, questions remain about conditions under which lichens can accelerate or retard the weathering of the rocks they grow upon. Generally it is believed lichens enhance rock weathering in humid climates and retard weathering processes in arid regions. Limestone composes a large percentage of the surface landscape of Kentucky, and thus the weathering of limestone is of particular importance in understanding the Commonwealth’s landscapes. For this project a variety of lichen species residing on limestone in the Warren County, Kentucky area have been located and identified. While many species of lichens reside in the area, a list was constructed of only endolithic lichens observed and sampled (including foliose species Anaptychia palmulata and crustose species Fuscidea recensa). Samples of limestone with and without lichen cover, and of varying lichen coverings, were collected and analyzed under a scanning electron microscope. Samples of the limestone surfaces directly under the lichen where compared to lichen free surface samples as well as samples of unweathered surfaces. Using this information, detailed descriptions of each particular lichen type’s influence on the weathering of the limestone samples are being developed for each species sampled.