Recent Warming and Cooling in the Antarctic Peninsula Region has Rapid and Large Effects on Lichen Vegetation

Leopoldo G. Sancho, Ana Pintado, Francisco Navarro, Miguel Ramos, Miguel Angel De Pablo, Jose Manuel Blanquer, Jose Raggio, Fernando Valladares, Thomas George Allan Green
2017 Scientific Reports  
The Antarctic Peninsula has had a globally large increase in mean annual temperature from the 1951 to 1998 followed by a decline that still continues. The challenge is now to unveil whether these recent, complex and somewhat unexpected climatic changes are biologically relevant. We were able to do this by determining the growth of six lichen species on recently deglaciated surfaces over the last 24 years. Between 1991 and 2002, when mean summer temperature (MST) rose by 0.42 °C, five of the six
more » ... species responded with increased growth. MST declined by 0.58 °C between 2002 and 2015 with most species showing a fall in growth rate and two of which showed a collapse with the loss of large individuals due to a combination of increased snow fall and longer snow cover duration. Increased precipitation can, counter-intuitively, have major negative effects when it falls as snow at cooler temperatures. The recent Antarctic cooling is having easily detectable and deleterious impacts on slow growing and highly stress-tolerant crustose lichens, which are comparable in extent and dynamics, and reverses the gains observed over the previous decades of exceptional warming. The Antarctic Peninsula is one of the regions on Earth that have experienced some of the largest warming rates during the last decades of the past century, and it has been predicted that this will continue at 0.34 °C per decade until 2100 1 . However, a recent analysis has shown a more complex situation. Mean annual temperatures in the Antarctic Peninsula rose at a rate of 0.32 ± 0.20 °C per decade from 1979 to 1997 and have fallen since then −0.47 ± 0.25 °C per decade from 1998 to 2014 2 . The single example available at present of vegetation response to increasing temperatures in the Antarctic corresponds to the only two vascular plants found there, Deschampsia antarctica and Colobanthus quitensis, both of which have shown local increases in populations and possible southward advances 3 . This has raised concerns about possible future colonisation by such species 4 if temperatures continue to rise as predicted. Manipulation experiments using OTC chambers have reported deleterious effects of both warming and snow accumulation for Usnea antarctica 5 . No report is yet available about the effect of recent cooling on Antarctic vegetation. Lichens are the dominant vegetation type in the Antarctic Peninsula and adjacent islands with over 400 species present and very high cover in the ice-free coastal areas 6 . However, no studies are available about the effects on lichens of either the 50 years of increasing temperature, or the recent decline in temperature. Monitoring of growth rates is considered the best available indicator of climate change in Antarctica with a 100-fold gradient in rates being found across the continent 7 . That means a dramatic response in annual growth of 30-50%, depending on the species, per 1 °C change in mean temperature. A major effect of warming in the Antarctic Peninsula region is the retreat of glacier fronts 8, 9 and, as a result, new land surfaces are becoming exposed providing opportunities for lichen colonization 10-13 . Avoiding competition, individuals of each species of these pioneering communities Published: xx xx xxxx OPEN www.nature.com/scientificreports/ 2 Scientific RepoRts | 7: 5689 | can develop in balance with environmental conditions and can indicate the trend in plant productivity for discrete time intervals over long periods of time.
doi:10.1038/s41598-017-05989-4 pmid:28740147 pmcid:PMC5524963 fatcat:x5vsxrqtffaevnjcv2lxo3xwfq