Study FSRM 1706-12 - Mesquite Removal

Study FSRM 1706-12: A Comparison of Vegetation and Grazing Capacities on Mesquite-free and Mesquite-infested Semidesert Ranges in Southern Arizona

S. Clark Martin designed this study to determine the vegetation response to largescale mesquite removal. It employed four pastures: on two pastures (1 and 7) all mesquite trees were killed with diesel oil; and on two pastures (8 and 10), the mesquite trees were left intact as control, or comparable, study sites.

Twenty permanently established study plots were located in each pasture (see Study Plan ASCII text file below). The experimental treatments were continued from 1957 through 1966.
Livestock use was controlled to contain utilization below 40 percent. In alternate years, livestock use was yearlong, and the following year it was excluded during the summer seasons only. Yearlong grazing continued throughout the study in a fifth pasture (9), which was measured for comparative purposes in 5 of the 10 years. 
Estimates of cover by species were made along 100-foot transects by stretching a graduated tape between permanently placed rebar stakes in the ground at either end of the transect. Basal intercept for perennial grasses and canopy intercept for shrubs and trees were measured to the nearest 0.01 foot.
Estimates of grass biomass production for each species were made at the end of each summer growing season using a double-sampling method. Biomass was estimated to the nearest gram on six 9.6-foot by 1-foot plots along each of the 100-foot transects. Clipped plots used for the double-sampling estimates were not located on the permanent transects. 
Based on the transect locations marked on aerial photographs, estimates of these locations were placed on mylar overlays of USGS 7.5' (1:24000) topographic quad maps of the SRER, and then digitized from the overlays. The UTM coordinates represent the digitized points reprojected to the NAD83 datum using the GRS1980 spheroid.

The results of the study are described in six publications. Cover and production measurements were continued on 20 of these study transects in “Forest Service Study FSRM 1706-25: Benefits of rest March-October two years out of three” (See the FSRM 1706-25 section below). Ten of those study transects are included in the Ongoing Vegetation Transects measured on the SRER since 1991.

This page provides the following contents related to the Study FSRM 1706-12.