Warming and snow experiment plant species composition data for Saddle snowfence, 1993 - 2000.

The International Tundra Experiment (ITEX) is a consortium of research
sites seeking to understand the response of tundra plant populations
to changes in growing season temperatures through a simple temperature
manipulation and transplant experiment. The research goal is to
examine the phenologic and reproductive responses of a set of species
to experimentally-induced warming at a network of sites. The ITEX
design is hierarchical, with sites participating at whatever level
they are able. At the minimum, participation in ITEX requires climate
monitoring (using the LTER MSR standards), a temperature manipulation
using one of three possible designs, and monitoring phenologic and
reproductive variables for at least one designated ITEX species or two
other species. The temperature manipulation is achieved through use of
conical or hexagonal open-top chambers of solar fiberglass, which have
been shown to increase the air temperature at the surface
approximately 3 degrees C. ITEX studies at Niwot Ridge, a logical
outgrowth of the long-term phenology studies there, uses a factorial
design based around the long-term snowfence experiment. Twenty cones
are placed behind the snowfence, distributed at 10, 25, 45, and 75 m
from the fence; each cone is paired with an adjacent plot. Beginning
with the 1995 season, 24 additional plots were implemented outside of
the snowfence influence. Twelve cones are distributed beyond both the
north and south edges of the snowfence area, at 10, 25, 45, and 75 m
behind the line of the snowfence; each cone is paired with an adjacent
plot. This results in the following treatments: increased winter snow,
increased summer temperature, increased snow and increased
temperature, and control. Key phenologic, growth, and reproductive
traits are being followed on marked individuals of Acomastylis (Geum)
rossii and Bistorta (Polygonum) bistortoides, and complete species
composition is being monitored. The point-quadrat technique used was
identical to that described by Auerbach (1992): The point-quadrat
method was used for estimating canopy stratification and plant cover.
Aluminum point-quadrat frames were 1-m^2 in size, with double-layer
filament spaced 10 cm apart to make a 10 x 10 cm grid for a total of
100 sample points per plot. Before sampling, the point-quadrat frame
was leveled and plots were permanently marked in the following manner.
Aluminum tags were nailed into the ground so that a frame could be
repositioned in the same location from year to year; i.e., tags with a
hole in the middle were used to define the locations for the point
frame legs and four tags with a "X" stamped on them
(positioned somewhere inside each of the frame corners) were used to
define alignment of the frame by positioning the string crossings over
these "X"s. Distances from the frame to a top canopy plant
hit and to a surface layer plant hit were measured to the nearest 0.5
cm and recorded. Plant genus and species were also recorded at both
hits at each point. CITATIONS. Auerbach, N. 1992. Effects of road and dust disturbance in
minerotrophic and acidic tundra ecosystems, Northern Alaska. MS
thesis, University of Colorado, Boulder. 253 pp.