Microclimate variability of Antarctic terrestrial ecosystems manipulated by open top chambers: Comparison of selected austral summer seasons within a decade

Abstract

Open top chambers (OTCs) were established in the northern part of the James Ross Island, Antarctic Peninsula, as a part of long-term program in January 2007. They were installed in two typical locations differing in vegetation cover. First group was set in a seashore ecosystem dominated by moss carpet supplemented with few lichen species. The other group was located on the top of a volcanic mesa (350 m a.s.l.) with irregular cover of lichens Usnea antarctica and Umbilicaria decussata. Temperature regimes inside and outside OTCs were continuously measured and related to year-round reference meteorological data. For majority of OTC installations, temperature increase caused by OTC was apparent in the period of September-March. Detailed analysis of chamber effect on the increase in air, surface, vegetation, and ground temperatures was done for late austral summer seasons of 2007 and 2008, and 10 years later, the seasons of 2017 and 2018. The OTC-induced temperature increase was more pronounced for mesa than seashore plot. For both locations, OTC-induced increase in temperature was highest for warm days with full sunshine and limited wind speed. On stormy days with overcast sky and high wind speed, the shift in temperature was smaller. Consequences of a long-term manipulation of Antarctic terrestrial ecosystems by OTCs for moss and lichen ecophysiology are discussed.