摘要：Recent observations suggest that while some arctic landscapes are undergoing rapid change,
others are apparently more resilient. In this study, we related surface cover and energy
balance to microtopography in a degraded polygonal peat plateau (baydjarakh field) near
Churchill, Manitoba in mid-summer 2010. The landscape consists of remnant
high-centered polygons divided by troughs of varying widths. Historical aerial
photos indicate these topographical features have been stable for over 80 years.
Our goal was to explore patterns that might explain the apparent stability of
this landscape over this time period and to evaluate remote sensing methods for
characterizing microtopographic patterns that might resist change in the face of
climate warming. Summertime surface albedo measurements were combined with
several years of winter snow depth, snow heat flux, summer thaw depth and annual
surface temperature, all of which had striking contrasts between wet troughs and
high polygon centers. Measurements of albedo and the snowpack heat transfer
coefficient were lowest for wet troughs (areas of standing water) dominated by
graminoids, and were significantly higher for high polygon centers, dominated by dwarf
shrubs and lichens. Snow depth, surface temperature and thaw depth were all
significantly higher for wet troughs than high polygon centers. Together these
patterns of cover and energy balance associated with microtopographic variation can
contribute to the stability of this landscape through differential heat transfer and
storage. We hypothesize that local thermal feedback effects, involving greater heat
trapping in the troughs than on the baydjarakh tops, and effective insulation on the
baydjarakh edges, have ensured landscape stability over most of the past century. These
results suggest that high-resolution remote sensing, combined with detailed field
monitoring, could provide insights into the dynamics or stability of arctic landscapes,
where cover often varies over short distances due to microtopographic effects.
