Moss banks

Low-lying moss growth, Ardley Island, South Shetland Islands, 2012.  Most moss does not usually form deep banks, instead growing to form a rippled carpet, making the most of the occasional sunny days after the snow cover has melted to grow.

Moss banks

Deep exposed moss bank, Elephant Island , South Shetland Islands,  2012.  Pictured: Prof. Dan Charman.  This is a naturally eroded face of the deepest known moss peat bank in Antarctica – all of the brown material is accumulated moss built up over thousands of years, preserving information about the environment at the time of growth.

What?

...are moss banks?

Here you will find more information on these fascinating accumulations of moss and how they can help us understand how the climate of the Antarctic Peninsula has varied over many thousands of years.

Over much of Antarctica, very little grows.  There are just two species of higher plants recorded, but over 350 species of mosses and lichens.  However, on the Antarctic Peninsula which is relatively far north in Antarctic terms, there is just enough warmth in the summer months to enable the mosses in the moss banks we are studying to grow by just a millimetre or so, before being frozen again during the long, cold, dark winter months.  The following summer, the mosses wake up again and grow a further millimetre.  When this sequence continues over long periods of time, banks of the mosses begin to form.  Although this seems like a very slow rate of accumulation, when we consider the length of time we are studying and the limits of the methods we are using, this allows us to develop records that would be described as high-resolution in terms of the temporal spacing of samples – about one sample per decade.

Peat moss banks are ideal archives for palaeoclimate research as they are well-preserved by freezing, can be dated easily using radiocarbon dating and are dominated by just one or two species, namely Chorisodontium aciphyllum and/or Polytrichum strictum.  Having cores dominated by only one species is good for our isotope studies as it means that any changes we see in the isotope ratios are more likely to be down to climate rather than changes in the mosses.

The photos here show how moss banks appear, both from the surface and also in cross-section, showing the many layers of moss that have built up over time.