A Comparison of Vegetation Responses to Grazing Yearlong, in the Growing Season, and in the Dormant Season on Low-Value Semidesert Grass-Shrub Ranges in Southern Arizona - Production data for 1957-1966 and 1970



The file prod09.xls contains net aboveground production data for perennial and annual grasses for USFS Study FSRM 1706-09. A copy of the Study Plan may be obtained at http://ag.arizona.edu/SRER/study09/study09.txt. Measurements were taken annually from 1957-1966 and in 1970 on 12 pairs of sample plots in each of 6 pastures. Each pair of plots was located at one of three distances from water and on one of two kinds of soil. Each pasture was subjected to one of three livestock grazing treatments. Pastures 3 and 5N were grazed during the winter dormant season (approximately November through April). Pastures 5S and 12B were grazed during the summer growing season (approximately May through October). Pastures 2N and 6B were grazed yearlong. Two permanent 100-ft. line transects were established at each plot location. One transect in each plot was a control, but all mesquite (Prosopis velutina) within 50 ft. of the other was killed. Herbage production was estimated in autumn as soon as possible after the end of the summer growing season. Estimates were on two 8x24 ft. subplots centered over each transect (with long axis along the transect). Production estimates were adjusted for utilization where necessary. Field weights were estimated in grams, then converted to dry weights using factors developed from double sampling. Dry weights were then converted into air-dry pounds per acre (to the nearest pound). Perennial grass data is recorded by genus or species. All species of annual grasses were combined into one measurement. Sources of data were original field data sheets and a printout of previously digitized data. 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. When measurements are entered for OTHERPG, the species and genera to which they refer are not consistent. In this study ARIS refers to the Aristida genus (specifically tall threeawns). A value of -9999 in a field means that no data were available because a reading was not made for that date. A value of -99 in a field means that the datum is unknown. Due to the method used to calculate air-dry pounds per acre, a zero entry may have one of two meanings: 1) The species did not occur at all in the plots, or 2) The species occurred in a quantity too small to round up to one pound per acre. The significance of a particular zero entry cannot be inferred from the table; field sheet review would be necessary.
Date made available2005
PublisherKNB Data Repository

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