The bryophytes collected in the years 1885, 1926-1935, 1972-1975 and 2006-2007 in Vertizarana Valley (Navarra, North Spain) have been studied, identifying or compiling 253 species. Fertility and Ellenberg's indicator values for light, temperature, substrate pH and nitrogen have been analysed. Results indicate that there have been small variations in Ellenberg's indicator values along the time span studied: the tendencies point at a decrease in light and increase in temperature and nitrogen, while substrate pH does not show a clear tendency. Regarding fertility, the overall number of species with sporophytes or sexual organs has decreased and several species seem to have lost fertility. All this suggests that changes in ecological conditions and air quality may have taken place in the Vertizarana Valley.