File: pex25.xls


Pex25.xls refers to production data from plots in USFS Study FSRM 1706-25 that were not formally included in that study. The file contains net aboveground production data for perennial and annual grasses.

Measurements were taken in autumn 1972 along ten permanent 100-ft. line transects in pasture 22. Since pasture 22 was not scheduled for forage survey in 1972, these data were not included in published analyses.

Pastures in Study 1706-25 were grazed either yearlong or according to a Santa Rita three-pasture rotation system.

Pastures were blocked by elevation -- high(1150-1340 m), intermediate(1040-1220 m), or low (880-1040 m).

The weight-estimate method was to estimate herbage production to the nearest gram only in pastures scheduled to be grazed during the next 12 months. Field weights were estimated on two 8x24 or five 9.6x1 ft. permanent plots and one temporary plot per transect. Herbage on temporary plots was clipped and weighed to calculate a factor for adjusting ocular estimates. Dry weights of clipped herbage provided a moisture correction factor. Field weights from the permanent plots were converted to grams per 96 sq. ft. plot. Grams per 96 sq. ft. plot were converted to the nearest 0.1 air-dry pound per acre by applying the factors.

In this file air-dry pounds per acre amounts are truncated at the decimal point except for amounts of 0.1-0.9, which are recorded as one pound per acre. Totals calculated from file values will generally be lower than ones calculated from field data due to truncation.

Taxa were recorded separately to the species level in most cases and sometimes to the genus level only. The ANNGRASS code refers to all annual grass species. In this study ARIS refers to tall Aristida species (specifically Aristida hamulosa and Aristida ternipes).

Sources of data were the original field data sheets.



pex25notes.txt
26 October 2001