Assessing the Potential Impacts of Elevated Temperature and CO₂ on Growth and Health of Nine Non-Vascular Epiphytes: A Manipulation Experiment

Abstract

The consequences of sharp rise in atmospheric carbon dioxide concentration ([CO 2 ]) and global warming on vascular plants have raised great concerns, but researches focusing on non-vascular epiphytes remain sparse. We transplanted nine common cryptogamic epiphyte species (3 bryophytes, 6 lichens) from field sites to growth chambers (control, elevated [CO 2 ], elevated temperature, elevated [CO 2 ] and temperature) and monitored their growth and health at regular intervals in a subtropical montane forest in Ailao Mountains in southwestern China. Our results implied a dim future for nonvascular epiphytes, especially lichens, in a warming world. The initial rise in temperature and decrease in water availability from field sites to the control chamber had remarkable negative impacts on growth and health of nonvascular epiphytes, many of which turned brown or died back. Although elevated [CO 2 ] in chambers had no significant effects on growth of any of the experimental species, further warming caused significant negative impacts on growth of Lobaria retigera (Bory) Trev. In addition, elevated [CO 2 ] and temperature have a significant interaction on growth of four experimental lichens. Considering the ecological importance of epiphytic bryophytes and lichens for the subtropical montane forest ecosystems and high sensitivity to environmental changes, people may underestimate global change impacts to nonvascular epiphytes, or even the whole forest ecosystems.