Plant phenology observations in the black sand extended growing season experiment for East Knoll, Audubon, Lefty, and Trough sites, 2018 - 2020.

As a result of climate change, the Rocky Mountain Front Range is
experiencing warmer summers and earlier snowmelt. Due to the
importance of snow for regulating soil temperature, growing season
length, and available moisture in alpine ecosystems, even small
shifts in the snow-free period could have large impacts. The focus
of the Black Sand Extended Growing Season Length Experiment is to
examine how terrain-related differences in climate exposure
influence the way alpine habitats respond to climate change via
earlier snowmelt. To simulate how climate exposure may affect plant
communities, NWT LTER researchers established 5 experimental sites,
each containing a pair 10 x 40m rectangular plots. These sites
include north and south facing aspects, subalpine and alpine tundra
meadows and a range of hydrological conditions (e.g. dry meadows,
moist meadows, wet meadows). We accelerated snowmelt in one plot at
each site by adding chemically inert black sand, while keeping the
second plot as an unmanipulated control; black sand was added to
control plots after snow had naturally melted. We used open top
warming chambers (OTCs) to increase summer temperature in three
subplots within each of the 10 x 40 m plots. This dataset includes
measurements of plant species phenology within all snow and warming
treatments at all sites except Soddie.