File: prod25.xls


The file contains net aboveground production data for perennial and annual grasses for USFS Study 1706-25. A copy of the Study Plan may be downloaded from the web site.

Measurements were taken each autumn from 1972-1980 and 1982 along permanent 100-ft. line transects in 12 pastures. Ten transects were measured in pastures 1, 2N, 2S, 3, 5N, 5S, 8, 12B, 21, and 22. Twenty-five transects were measured in pasture 6A and 20 transects in pasture 6B.

Pastures 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).

Mesquite treatments on transects established for earlier studies are coded in the file as follows: DEAD for mesquite (Prosopis velutina) killed in USFS Studies FSRM 1706-09 and FSRM 1706-12, and LIVE for transects on which mesquite was left untreated.

The weight-estimate method was used 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 the 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 OTHERPG code refers to unidentified perennial grass species; ANNGRASS 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. Field data sheets were available only for 1972-1975, and only these data are included in the file. Digital data for 1976-1980 and 1982 could not be verified so these data are NOT included.

A value of -9999 in a field means that no data were available because a reading was not made for that date. Values of -9999 recorded for all species in pasture 22 in 1972 indicate that, although measurements were made, the data are not included because they were not analyzed as part of Study FSRM 1706-25.



prd25notes.txt
26 October 2001