Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Abstract

Summary 1The response of peat-rich permafrost soils to human-induced climate change may be especially important in modifying the global C-flux. We examined the Holocene developmental record of a High Arctic peat-forming wetland to investigate its sensitivity to past climate change and aid understanding of the likely effects of future climate warming on high-latitude ecosystems. 2 The microhabitat of mosses was quantified in the present-day polygon-complex at Bylot Island (73 ° N, 80 ° W) and used to interpret the radiocarbon-dated macrofossil record of three cores, comprising c. 3500 years of wetland development. Recurrent wet and dry phases in the reconstructed palaeohydrological record indicated pronounced temporal variability. Wet and dry phases were compared between cores and with palaeoclimatic proxy values, measured as percentage melt and δ 18 O in nearby ice cores. 3 Periodic wet and dry phases appear unrelated to past climate over c. 50% of the combined stratigraphic records, and are attributable instead to geomorphological mechanisms. At other times, association of wet and dry phases with significantly lower and higher values of percentage melt and δ 18 O indicate a possible effect of past climate change on polygon hydrology and vegetation, although inconsistencies between cores suggest that local geomorphological processes continued to modify a regional climatic effect. However, during a period incorporating the Little Ice Age ( c. 305-530 cal. years  ), reconstructed moisture and vegetation change is pronounced and consistent among all three cores. 4 The results provide strong evidence for the sensitivity of a High Arctic terrestrial ecosystem to past climate change during the Holocene. The estimated magnitude of changes in soil moisture between wet and dry phases is sufficient to imply recurrent shifts in wetland function, periodically impacted upon by pronounced climatic variability, although controlled principally by autogenic processes. The structure and function of such wetlands may therefore be susceptible to predicted, human-induced climate warming.

Environmental and taxonomic controls of carbon and oxygen stable isotope composition in <i>Sphagnum</i> across broad climatic and geographic ranges

“…Hence, variation in tissue oxygen isotopes reflect environmental conditions that control source water (rainfall, snowfall, groundwater) as well as fractionation caused by evaporation prior to fixation which is controlled by micrometeorological conditions (mainly temperature, relative humidity and incident energy) (Daley et al 2010, Moschen et al 2009, Royles et al 2013, Kaislahti Tillman et al 2010. Oxygen isotope composition has, therefore, been used to reconstruct climatic conditions and to infer the dominant water source in peatlands (Aravena and Warner 1992, Ellis and Rochefort 2006, van der Knaap et al 2011). …”

“…Paleoecological studies rely on such environment-isotope relationships for environmental reconstructions (Ellis andRochefort 2006, van der Knaap et al 2011). The underlying mechanisms are, however, rarely fully explored using known environmental gradients (but see Ménot and Burns 2001 for an example), or only tested across narrow bands of environmental variation, often with sets of correlated environmental factors (Loader et al 2016).…”

Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard) – environmental and climatic implications for the late Holocene

“…A very rapid peat growth is assumed during this period, probably driven by a warmer climate regime. Favourable climate conditions for peat growth in the high Arctic are strongly controlled by temperatures and soil moisture content (Ellis and Rochefort, 2006). Evidence from marine records indicates warmer temperatures in Svalbard from the beginning of the Holocene until ca.…”

Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns

“…Bylot Island wetlands have received some attention in the literature (e.g. Ellis and Rochefort 2006); however here, research has focused essentially on moisture control of eco-physiology, nutrient cycling, decomposition and carbon flux processes. Aerial reconnaissance in 2010 indicates that Polar Bear Pass is representative of other large wetland systems on Bathurst Island (e.g.…”