The objective of this research was development and testing of a method for estimating cattle carrying capacities. A series of studies were conducted in developing this method. Range site and vegetation production data were grouped by topographic position and multiple linear regression equations were calculated for predicting vegetation production as a site deviated from the average case of a given range site. Overstory-understory relationships from the literature were adapted into overstory canopy cover classes for predicting understory production and tested on a variety of range sites. Use of these classes produced understory biomass estimates within 13% of measured biomass. Range condition class and understory aspect dominance by forage vs. non-forage species were investigated as estimators of forage value of the understory vegetation. Both were significantly related to amount of forage in the understory. However, understory aspect proved to be a better estimator when individual comparisons were examined. The previous findings, along with Soil Conservation Service range site guides, were used to calculate resource value ratings. Adjustment factors to be applied to the resource value ratings were calculated, using data from the literature, to account for the effects of slope and distance from water on forage utilization by cattle. These resource value ratings and adjustment factors form the basis of the carrying capacity estimation method. Pastures identified as properly utilized were used in testing the method developed. Pastures were mapped for range site, vegetation, slope and water location. Maps were converted to digital form and analyzed using the Map Analysis Package (MAP) computer program (Tomlin, 1975). Construction of a final range site-vegetation-slope-distance from water map, assigning of resource value ratings and adjustment factors, and computation of final carrying capacity estimates were accomplished using MAP. Carrying capacity estimates from the developed method were well correlated to estimates from ocular reconnaissance and area allowable use methods, r = .87 and .97, respectively, and with the actual use (perceived proper use), r = .95. These estimates were accomplished without intensive field sampling. The only information required was range site designation, amount of overstory canopy cover, understory aspect class, percent slope and water location.

Revised publication

No description available.

Arizona Cooperative Extension Publication 190043 / Originally published 1990, revised 1995, revised 1997.

Arizona Cooperative Extension Publication 190043 / Originally published 1990, Revised 1995.

No description available.

No description available.

No description available.

The purposes of this study were to compare Soil Conservation Service and Forest Service methods for determining range condition, to develop a method for determining range condition using plant frequency data and to develop range condition guides using Sorensen's coefficient of similarity. The final objective was to compare condition scores based on frequency data to Soil Conservation Service and Forest Service condition scores. Loamy upland and sandy loam upland range sites in the Empire Valley and Santa Rita Experimental Range of southeastern Arizona were sampled. Three prominent soil series of upland range sites within the study area were selected for study. Within each soil series, areas of apparent high, medium and low levels of past and present livestock use were sampled at three locations. Soil profile descriptions were made for each of the 27 sample areas and soil characteristics were used to confirm soil series sampled. Plant communities were sampled by weight estimates, Parker 3-step transects and 40 x 40 cm frequency plots. Forest Service and Soil Conservation Service condition scores did not correlate well within the loamy upland or sandy loam upland range sites. Condition scores by both methods, especially for Forest Service data, are confounded with site potential. Cluster and factor analysis procedures identified plant groups associated with soil series, range site and sample location. Range condition was not identified as a criterion of plant group association. Sorensen's coefficient of similarity scores for frequency data based on a specific "high condition" reference area had a high coefficient of determination value when correlated with Soil Conservation Service condition scores for loamy upland range sites. Forest Service condition scores had a very low coefficient of determination value for the same comparison. Soil Conservation Service and Forest Service condition scores compared to similarity scores for frequency data for the sandy loam upland range site had positive but low coefficient of determination. Sorensen's coefficient of similarity, using frequency data as an index of condition, can be used to develop a range site condition guide for a homogeneous range site.

No description available.