Each study site is 1 km by 0.5 km in area. Four replicate experimental
blocks were randomly located at each study site depending on whether
the site was grazed. The blocks are all oriented on a site in an X/Y
coordinate system, with the access road to each site forming the X
axis. The compass orientation at the Jornada grassland site is to the
north, and Jornada creosotebush site is oriented to the south.
Treatments within each block include one unfenced control plot
(Treatment: C; control); one plot fenced with barbed wire, hardware
cloth, and poultry wire to exclude rodents, rabbits, and cattle
(Treatment: R; rodent); one plot fenced only with barbed and poultry
wire to exclude cattle and rabbits (Treatment: L; lagomorph); and one
plot fenced with barbed wire to exclude cattle (Treatment B; bovine).
Cattle exclosure plots with barbed wire occur only at the black grama
grassland site where cattle were present, for a total of 4 treatment
plots at each of the four grassland site blocks. There are only 3
treatment plots at each of the creosotebush site blocks. The
treatments were randomly assigned to each of the three or four
possible plots in each block independently, and their arrangements
differ from block to block. Each of the plots in a replicate block is
separated by 20 meters. Each plot measures 36 meters by 36 meters.
Thirty-six sampling points are positioned at 5.8-meter intervals on a
systematically located 6 by 6 point grid within each plot. A permanent
one-meter by one-meter vegetation measurement quadrat is located at
each of the 36 points.
All count values are measured from the vegetation measurement frame,
which is 1 meter by 1 meter, and partitioned into a grid of 100, 10 cm
by 10 cm squares. Twice a year in the spring and fall from 1995-2005,
total rabbit feces cover in each quadrat was counted. Each pellet was
was collected in a bag for each quadrat. After 2005, sampling
frequency changed to once every 5 years in the fall, and the sampling
method changed. In all measurements after 2005, only the presence or
absence of pellets (as a 1 or 0) is recorded for each quadrat instead
of a count.
Field observations were recorded on micro-cassette tape recorders.
Further details on measurements and data preparation can be found in
the SMES vegetation quadrat protocol included with this package:
SMESvegquadprotocol.pdf
