Print PageFerns have received little attention from a phenological and physiological perspective. As one of the oldest and most widespread lifeforms they have persisted through past periods of global climate change. Here we utilized a novel analysis of historical records combined with an innovative physiological approach to test the hypothesis that fern species with the ability to alter their phenologies should be more successful under future climate conditions. One hundred year old historical observations of local fern populations made by Alfred Hosmer are the basis for this study. Based on analysis of these data, two species in the same genus and with similar light and water requirements were chosen for this study; Osmunda cinnamomen (Cinnamon fern) which exhibits spore release dates significantly correlated with the mean temperature two months prior to spore release and Osmunda regalis (Royal fern) a species with spore release dates that are not correlated with temperature. In October 2009 these species were planted in an experimental setup at the Boston Area Climate Experiment and natural locations in Massachusetts in environments that exposed plants to altered temperature and water conditions. A repeated series of phenological and physiological measurements were taken in 2010.
Results/Conclusions
After the first year of research it appears that Cinnamon ferns are phenologically and physiologically more plastic than Royal ferns and are better able to adjust to various climate conditions. Cinnamon ferns exhibited a range of growth with exposure to increased temperature and variable precipitation over the growing season. Royal ferns were more narrow in their responses and quicker to die back when conditions grew less hospitable. Results from pressure chamber measurements indicate that Cinnamon ferns have significantly different water potentials across treatments (ANOVA p = 0.02), signifying that plants differ in their ability to take up water from dry soils. A significant relationship did not exist for the Royal ferns, suggesting that this species is less able than Cinnamon ferns to adjust its physiology in response to a drier environment. Flexible physiology and phenology may be a partial explanation for the greater success of Cinnamon versus Royal ferns. The combination of Hosmer’s historical records on fern phenology, the addition of current observations, and the data collected from this innovative experimental study will have substantial and direct implications for understanding ferns and their current and future role in New England ecosystems.
