Field operations for E110
Draining of rain water
A small trench is maintained to the south
side of drought plots to let sheltered-off water drain away. The dirt from
these trenches is stored for later replacement on a sheet of plastic adjacent
to the site in each field. Precipitation measurement: Modified 1.5 l plastic
Coke bottles are used (2 per treatment in each field) to measure precipitation
in the drought season (day 130 through day 240). Outside this period data
from the weather station at Cedar Creek are used. Mammal trapping: Gophers
are trapped and removed from field A as they appear, in field C they are not a
problem.
Seedbank
Seedbank samples (2"wide, depths 0-1.5cm, 1.5-5.75cm,
5.75-10cm) are cut on October 24, two per plot, hammering an alu tube down.
Samples are stored over the winter in a dark fridge (4 C) and germinated in
the spring in first week of April.
Soil nitrogen
Nitrogen is sampled (0.01M
KCl) mid monthly from April through November. To assess mineralization PVC 1",
1 ft tubes are inserted 5 cm away at the time of sampling to prevent uptake
and leaching, and collected the next month.
Germination
Germination is monitored in 0.1x1m strips in each plot every two weeks,
to begin in early May. Plants are staked and positioned with coordinates.
Plant demography
Approximately 20 individuals per plot per species are staked and positioned
with coordinates, randomly chosen across the entire 3x3 m plot area. Plots
are monitored three times per season: at the start of the early drought
(middle May); at the end of early and the start of late drought (beginning of
July); and at the end of the late drought (end of August).
Below ground biomass
Rootcores are taken with 2" alu pipe, 0-10; 10-20 etc to 100cm depth
in each plot in end October. Samples are weighed, air dried, weighed and
sieved.
Above ground biomass
Clipping and sorting of a 10x300 cm strip is
done in early August. A 'clipping frame' is used to enclose and demark the
vegetation to be clipped by descending it down vertically onto the plot, and
clipping all vegetation enclosed (including parts that might cross the plot
but grow outside).
Soil moisture
Moisture profiles to 1m depth are measured
through a neutron probe (and gravimetrically for shallowest samples) every two
weeks.