Relationship of Terrestrial Mosses to Forested Flood Plains in Southeastern Ohio

Abstract

Eurhynchium hians (Hedw.) Sande-Lac. was the dominant of six species of mosses found within three forested flood plain stands along the Hocking River near Athens, Ohio. Low light levels (<10% full sunlight) during the summer, caused by a dense cover of vegetation, and occasional flooding enhances protonemal growth. Regeneration of these mosses from fragments of leafy gametophytes was tested in the laboratory. Regrowth from buried plants and fragments of plants emerged through deposits of alluvium up to 10 cm thick. Regeneration and emergence from burial by alluvium seem to be important modes of establishment of terrestrial mosses on flood plains. Mosses within river systems have been the subject of several studies (Glime, 1968; Flowers, 1973; Empain, 1973; and others). These studies primarily dealt with aquatic or subaquatic habitats within the limits of river beds. With the exception of Wistendahl (1960), little attention was given to the occurrence of mosses on flood plains. The present study deals with the effects of vegetation and flooding on terrestrial mosses within three flood plain sites along the Hocking River in southeastern Ohio. The study was limited to terrestrial mosses because they are affected more by the deposition of alluvium than those growing on trees, logs or debris within the flood plain. Two main processes, deposition and erosion, are involved in the dynamics of flood plains and flood plain vegetation (Wolman & Leopold, 1957; Wistendahl, 1958; Sigafoos, 1964; Dury, 1970). Generally, the frequency of floods and their magnitudes are inversely related. Small floods of short duration may occur seasonally but major floods occur only once in 50 to 100 years. There were three, three-day floods on the Hocking River during the study period. These occurred in December 1972, April 1973 and June 1974. A flood of six days duration occurred in September 1974. None of these floods was severe enough to be considered a major flood such as the flood of 1964. Hood (1967) summarized the geologic history, soils, climate, flooding and vegetation of the 150 km Hocking River which drains 3000 km2, mostly in rural southeastern Ohio. 1 Grateful acknowledgment is made to Dr. Lewis E. Anderson for assistance with the identification of sterile specimens of mosses. This paper is based on a thesis submitted by the first author in partial fulfillment of the requirements for the Degree of Master of Science, Ohio University. 2 Present address: Department of Botany, University of Tennessee, Knoxville, Tennessee 37916. SDepartment of Botany, Porter Hall, Ohio University, Athens, Ohio 45701. This content downloaded from 157.55.39.105 on Fri, 07 Oct 2016 04:49:18 UTC All use subject to http://about.jstor.org/terms 1976] McFARLAND & WISTENDAHL: FLOOD PLAIN MOSSES 65 Specimens of mosses were collected, identified and deposited in the Bartley Herbarium (BHO) of Ohio University. Verification of all species of mosses and the identification of Brachythecium oxycladon (Brid.) Jaeg. & Sauerb. were made by Dr. Lewis E. Anderson, Duke University. Nomenclature of mosses follows Crum et al. (1973).