Antarctic Ecosystems

Background

The McMurdo Dry Valleys of Antarctica are an ice-free polar desert ecosystem, and may be uniquely impacted by UV-B for several reasons.  First, the southern polar region has experienced the biggest decrease in stratospheric ozone due to its interactions between aerosols (primarily CFC’s) and ice particles (discussed in detail here).  Organisms in this region may be especially impacted by this because the poles typically receive the least amount of solar radiation in comparison to lower latitudes on the globe, so they are likely less adapted to higher levels.

The ozone hole over Antarctica

Second, as these regions are highly limited in both primary production (devoid of higher plants and thus restricted to algae and mosses) and microbial processes.  The primary factors in these limitations are the extreme cold (temperatures only get above freezing for brief periods during the Austral summer), and the system’s aridity.

Taylor Valley, Antarctica - one of the largest of the McMurdo Dry Valleys. As you can see, a fairly desolate place...

Together, these factors minimize the presence of life in the Dry Valleys, leading to minimal carbon inputs into the soils (algae and mosses are sparse and contribute far less carbon than higher plants), as well as minimal nutrient turnover by microbes.  As a result the amount of organic matter in soils is very low; in fact, much of it is thought to be a legacy of when lake levels went up to much higher elevations in the Valleys than they do today, leaving behind sediments rich in organic nutrients (Burkins et al., 2000).

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