Download Data Methods Manual. - Konza Prairie

SUMMARY OF CHANGES
PRE021: Prior to 1994, at the first 10 points (or first 10 plants sampled), the inflorescence of each
individual was clipped and placed in a separate bag. The seed heads were oven dried at 60°C and
weighed. From this data (n=40 plants per species), mean seed weight per plant was calculated for
each species at each LTER site.
PRE022: Prior to 1992, following drought years (when reproduction by the three species
may be very low) flowering stem density was estimated during the fall by counting flowering
stems in the 10m2 circular plots. Flowering stem height and seed weights were measured on those
species flowering adjacent to the transects. Using this technique, sample size was variable for
flowering stem height and seed weight measurements. Low sample sizes may necessitate pooling
replicate LTER treatments.
Grazed Watersheds (exclosures): Measured 1987 - 1992. Height and density of flowering stems:
In each grazed LTER watershed there were eight permanent 5 x 5 m grazing exclosures, four
located on Tully soil sites and four located on Florence soil sites. Adjacent to each permanent
exclosure, another 5 x 5 temporary exclosure was erected and remained in place only during the
year during which stem density and biomass data were collected and only from May 1 until the
vegetation reached peak biomass. This provided exclosures in pairs, the permanent exclosure half
providing an un-grazed treatment and the temporary exclosure half providing a grazed treatment
(grazing is only temporarily prevented to allow re-growth biomass and flowering stem
measurements).
Watershed
N01A
N01A
N01B
N01B
N04A
N04A
N04D
N04D
Site
Florence
Tully
Florence
Tully
Florence
Tully
Florence
Tully
Exclosure Nos.
1–4
5–8
1-4
5–8
9 – 12
13 – 16
9 – 12
13 – 16
Year started
1988
1988
1992
1992
1988
1988
1992
1992
Within both the grazed half and un-grazed half of the paired exclosures, four 50 x 50 cm quadrats
were randomly distributed (excluding the edge within 1 m of the exclosure fence) and the number
of flowering stems of each of the three grass species were counted and recorded. In addition, four
of the flowering stems of each species were randomly selected and their heights were measured to
the nearest cm. The density of flowering stems (No. per m2) and mean flowering stem height were
calculated for each species at each LTER site.
BRIEF HISTORY OF THE PRE021-PRE022 DATA SET
In 1981, a study was initiated on seed production and flowering culm density of
Andropogon gerardii (ANGE), Sorgastrum nutans (SONU), and Schizachyrium scoparium
(ANSC). This study measured the flower stalk density, height and seed production for each
species. The objective of these measurements was not for population/demographic studies, but
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