Effects of Simulated Rain and Cement Amendments on Protonematal Growth of the Urban Moss, Bryum capillare, in Culture

Abstract

Abstract Bryum capillare, a moss of worldwide distribution, is ubiquitous to cities where it is commonly found growing within the cracks of sidewalks. Because of its occurrence in the harsh and depauperate urban environment, it was hypothesized that this moss is resistant to the deleterious effects of pollutants, such as acid rain. We tested this by measuring the growth response of an axenic culture line of B. capillare to simulated pH-adjusted rain. Field and experimental data both suggest that B. capillare is not especially resistant to acid rain. In the first experiment B. capillare protonematal cultures were subjected to simulated rain at pH levels between 3 and 8. Cultures at pH 4.0 simulated rain resulted in an approximate 50% reduction in colony area from that obtained in the pH 8.0 treatment. Therefore, we would expect the acid rain in Washington, DC to be unfavorable to the growth of B. capillare. Yet, the moss is both common and abundant in the city. In a second experiment the optimal pH for the...