Climate warming in polar regions is associated with thawing of permafrost, resulting in significant changes in soil hydrology, biogeochemical cycling, and in the activity and composition of soil communities. While ongoing directional climate warming presses can elicit such responses over decadal time scales, their manifestation typically occurs as discrete thawing pulses. Indeed, in the McMurdo Dry Valleys of Antarctica, abrupt changes in community structure and biogeochemical cycling in terrestrial and aquatic ecosystems following a summer warming event (Jan. 2002) exceeded the influences of a decadal cooling trend in both magnitude and rate of response. Thus, we anticipate that climate-mediated permafrost changes and their associated impacts on soil communities and biogeochemical cycles may occur over seasonal time scales. The Pulse-Press Project (P3) experiment was established in 2012 as part of the McMurdo Dry Valleys Long Term Ecological Research (LTER) program to investigate impacts of seasonal wetting on ecosystem structure and functioning by simulating different frequencies of permafrost thawing events in Antarctic permafrost soils. Since the top horizons of most Antarctic soils are dry permafrost (i.e., there is insufficient water content to generate ice-cement), with ice-cement or massive ice typically below 30 cm, permafrost thawing events are likely to result in subsurface movements of water that may manifest as groundwater seeps down gradient. The P3 experiment consists of three permanent plots situated on the south-facing hillslope above Many Glaciers Pond in Taylor Valley. Each plot is 15 m by 7.5 m with a trench on the upslope end that is used for experimental wetting events. The Press plot receives water every austral summer, the Pulse plot receives water every other austral summer, and the Control plot never receives water, serving as the ambient treament. Each plot is instrumented with a network of soil moisture and temperature sensors, positioned at 13 locations along the hillslope in vertical arrays at varying depths. This data package consists of these continuously recorded soil temperature and soil moisture data, complementing other data packages associated with the P3 experiment.
