Abstract
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 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.
Highlights
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]
We propose that the most likely causal factors for the loss of some thalli are increased snow fall and longer lasting snow cover, both of which are known to lead to lichen death, the so-called “snowkill”[14]
These results agree with long term studies carried out on the South Shetland Islands and in Antarctic Peninsula which, at the beginning of this century, show a break in the positive trends of both snow accumulation and length of the melting season detected in the past decades[18, 19]
Summary
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. No report is yet available about the effect of recent cooling on Antarctic vegetation. Can develop in balance with environmental conditions and can indicate the trend in plant productivity for discrete time intervals over long periods of time
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