George B. Ruyle

Spread of introduced Lehmann lovegrass Eragrostis lehmanniana Nees. in Southern Arizona, USA

Abstract Through seeding and subsequent spread, Lehmann lovegrass Eragrostis lehmanniana Nees. has transformed the structure and function of at least 145 000 ha of semi-desert grassland in southern Arizona since its introduction in 1932. Our study of its spread on the Santa Rita Experimental Range since 1954 showed that by 1989 it was present on >85% of 75 relatively widely dispersed non-seeded permanent plots and accounted for >40% of all perennial grass plants on these plots. In addition, it represented >50% of the perennial grass plants on sites 90% of the grass biomass and produce 2–4 times more biomass annually than native grass vegetation. In the future, strong consideration of these plant composition changes, and the likely decrease in wildlife diversity and increase in fire frequencies accompanying Lehmann lovegrass dominance, should be made before seeding the species.

Cattle use visual cues to track food locations

We tested the hypothesis that cattle aided by visual cues would be more efficient than uncued animals in locating and consuming foods placed in either fixed or variable locations within a 0.64-ha experimental pasture. Eight yearling steers were randomly selected and trained to associate traffic barricades and traffic cones with high- (oat-barley mixture) and low- (straw) quality foods, respectively. Initially steers were randomly assigned to 1 of 4 food location/visual cue treatments: fixed locations/with cues (F/C), variable locations/with cues (V/C), fixed locations/no cues (F/NC), or variable locations/no cues (V/NC). High- and low-quality foods and their respective cue (or no cue) were placed in the experimental pasture. Individual animals were allowed to explore the pasture for 10 min twice per day every other day for 1 week. Minutes until feeding, first feed type consumed (i.e., high-quality, low-quality, or no food consumed), animal location and activity (i.e., feeding, standing, or moving), and total intake of high- and low-quality feed were recorded during each 10-min trial. At the end of each week, location/visual cue treatments were randomly assigned to another 2 steers, which permitted an independent test of each animal in each treatment over a 4-week period. Animals in the F/C and V/C treatments took about 2 min to initially locate and consume a food, compared to F/NC and V/NC animals who took nearly 4 and 6 min, respectively. The high-quality food was the first food located and consumed by F/C, V/C, F/NC, and V/NC animals during 79, 77, 67, and 54% of sampling occasions, respectively. Cued animals typically spent more time feeding (P=0.0004) and less time standing (P=0.005) than uncued animals. Cued animals had a higher mean intake than uncued animals of high- (P=0.001) and low- (P=0.04) quality food. Mean high-quality intake for F/C, V/C, F/NC, and V/NC treatments was 266, 245, 214, and 126 (+/-22) g, respectively; mean low-quality intake for the same treatments was 36, 32, 12, and 10 (+/-10) g. Cued animals also consumed more food per distance traveled than uncued animals (P=0.005). Animals located food quicker (P=0.03) and consumed more high-quality food (P=0.02) when food locations were constant than when they were variable. Our data strongly indicate that cattle can learn to associate visual cues with disparate food qualities and use this information to forage more efficiently in both fixed and variable foraging environments.

The influence of residual stems on biting rates of cattle grazing Eragrostis lehmanniana Nees

Abstract On semi-arid rangelands, stems and other standing dead material may accumulate in bunch-grasses and restrict access to new growth by grazing animals. We found that the presence and heights of residual stems in Lehmann lovegrass ( Eragrostis lehmanniana Nees) increased the times between successive bites taken by grazing cows, thus decreasing biting rates when compared to bites taken where these stems were reduced. As new tillers elongated, biting rates increased but remained lower on those plants with the greatest amounts of residual stems. Ingestive behavior of cows may be influenced by distinctive features of the vegetation available at each bite taken. The number of bites cows take on grass plants containing large amounts of residual herbage could influence the average biting rate during a foraging bout. Methods of collecting biting-rate data should account for these influences.

Forest Service Grazing Permittee Perceptions of the Endangered Species Act in Southeastern Arizona

Abstract This study reports the results of a survey of Coronado National Forest grazing permittees about their attitudes regarding the Endangered Species Act (ESA) and the management of threatened and endangered (T&E) species on grazing allotments in southeastern Arizona. A majority of respondents perceived negative impacts from ESA implementation. However, the degree of impact remained independent of the number of listed species on allotments and of the potential for restrictions on those allotments. Perceptions of negative impact and attitudes toward T&E species policies were more related to attitudes toward federal regulation. Permittees broadly supported the idea of species conservation and expressed willingness to work with federal agencies but did not perceive the federal agencies as having the same responsiveness to their concerns. A more proactive agency strategy with science-based, focused recovery objectives coupled with economic incentives could improve support for species recovery efforts.

Effects of herbivory on twig dynamics of a Sonoran Desert shrub Simmondsia chinensis (Link) Schn.

(1) Density of jojoba (Simmondsia chinensis) was similar but plant size and cover were greater inside than outside a 48-year-old livestock exclosure in central Arizona. (2) Branch diagrams and destructive samples of ungrazed, moderately grazed and heavily grazed shrubs were taken over a 2-year period to determine twig responses to herbivory. (3) Twig growth was greatest in the spring while greatest herbivory occurred in late spring and summer after senescence of annual herbaceous plants. Grazed shrubs had greater twig growth than ungrazed shrubs resulting in similar net increases in twig length and biomass. The ability of jojoba to regrow from lower lateral or apical buds after removal of outer twig ends allows it to tolerate herbivory in the ecological context of the study site. (4) Grazed shrubs had lower male and female flower densities than ungrazed shrubs. (5) Periodic spring rest or control of stocking to limit grazing intensity is recommended to maintain shrub size and total production.

AGWA: The Automated Geospatial Watershed Assessment Tool to Inform Rangeland Management

AGWA: The Automated Geospatial Watershed Assessment Tool to Inform Rangeland Management DOI:10.2458/azu_rangelands_v33i4_goodrich

Beef and Beyond: Paying for Ecosystem Services on Western US Rangelands

Beef and Beyond: Paying for Ecosystem Services on Western US Rangelands DOI:10.2458/azu_rangelands_v33i5_goldstein

Very-High-Resolution Panoramic Photography to Improve Conventional Rangeland Monitoring

Abstract Rangeland monitoring often includes repeat photographs as a basis for documentation. Whereas photographic equipment and electronics have been evolving rapidly, photographic monitoring methods for rangelands have changed little over time because each picture is a compromise between resolution and area covered. Advances in image sensors, storage media, and image-processing software allow enormous amounts of information to be collected efficiently and inexpensively, so multiple pictures taken at full zoom can be combined into a single high-resolution panoramic image. This project was initiated to integrate very-high-resolution panoramic images with conventional rangeland monitoring methods addressing three resource management categories: riparian areas, wildlife, and invasive species.

Arizona permittee and land management agency employee attitudes toward rangeland monitoring by permittees

Abstract Ongoing conflicts over the management of western rangelands can be attributed in part to the lack of reliable information about current ecological conditions and their causes due, in turn, to insufficient monitoring. To meet the monitoring shortfall, land management agencies increasingly are enlisting permittees to monitor their grazing allotments. We surveyed grazing permittees in 5 Arizona counties and land management agency employees throughout Arizona to compare their attitudes toward permittee monitoring on public rangelands, the role of government in rangeland management, rangeland conditions in Arizona, and the credibility of information sources about rangelands. Permittees and agency employees differed in most of the attitudes measured by our survey. However, both populations agreed that permittees should participate in monitoring their allotments, and many respondents agreed with making permittee monitoring mandatory. Many respondents in both groups also agreed that collaboration can be beneficial. Joint monitoring, which can be considered a type of “joint fact-finding,” may help improve agency–permittee relationships and bridge the gap in attitudes and underlying values. Permittee-monitoring programs deserve careful evaluation to determine their impacts on social relationships, management decisions, and ecological conditions.

Mineral assessment in Atriplex halimus L. and Atriplex nummularia L. in the arid region of Jordan

The foliage of Atriplex halimus contained higher levels (P < 0.05) of ash (28.03%) than that of Atriplex nummularia (23.11%). Spring growth of the two saltbushes contained less ash than the fall regrowth. The foliage of A. halimus contained higher levels of macro-minerals than A. nummularia plants except sodium. The two saltbushes contained higher levels of P, K and Mg during spring, but lower levels of Ca and Na compared to the growth of the fall season. Levels of Fe, Cu, Mn and Se present in the foliage of A. nummularia plants were higher than A. halimus. Clipping had no significant effect on ash content of saltbushes, but it affected the composition of the ash significantly. Clipping decreased the concentrations of Ca, P, Na, Mg and Fe in the foliage of clipped shrubs. The mineral composition of the two species of Atriplex appeared adequate to meet the requirements of sheep and goats grazing such types of forage.