Water quality impacts of free ranging cattle in semi-arid environments

The purpose of this study was to evaluate the effects that free ranging cattle have on water quality in semi-arid environments. There were three specific objectives: 1) To determine the concentration and distribution of cattle feces in meadows, riparian zones, and the associated uplands. 2) To determine the fecal deposition rate of free ranging cattle directly into a stream. 3) To determine if feces near a stream, up to 2.3 meters away, are a source of pollution during rainfall and subsequent surface runoff. As the distance from water and slope increased cow-chip concentrations decreased. The highest concentration of cow-chips was found in the meadows where winter supplemental feeding occurred. The second highest concentration of cow-chips was found in the riparian zones. Areas that had steep slopes and were a long distance from water had the lowest concentration of cowchips. The amount of time the cattle spent in the stream and the fecal deposition rate changed by season. The cattle spent the most time in the stream during the summer, and the least amount of time during the fall. The direct fecal deposits were highest for summer and approximately the same for the other seasons. In the experiment designed to evaluate the effectiveness of buffer strips, feces were placed varying distances from the edge of simulated rainfall plots and subjected to different levels of precipitation. A significant reduction in conform concentrations was noted between the bacteria which traveled 0.7 meters through a buffer strip, as compared to those which did not have any distance to travel. Bacteria concentrations at the 0.0 meter distance averaged 42,800 coliforms/ml, whereas there were only about 2,250 bacteria/ml delivered from the feces deposited 0.7 meters away. No statistical differences were found between buffer strip widths of 0.7 meters and 2.3 meters. Buffer strip effectiveness for widths greater than 2.3 meters were not investigated and thus remain a subject for further investigation

A One-Pot Tandem Olefin Isomerization/Metathesis-Coupling (ISOMET) Reaction

A tandem catalytic reaction has been developed as part of a process to discover tungsten-based olefin metathesis catalysts that have a strong preference for terminal olefins over cis or trans internal isomers in olefin metathesis. This tandem isomerization/terminal olefin metathesis reaction (ISOMET) converts C[subscript n] trans internal olefins into C[subscript 2n–2] cis olefins and ethylene. This reaction is made possible with Ru-based “alkene zipper” catalysts, which selectively isomerize trans olefins to an equilibrium mixture of trans and terminal olefins, plus tungsten-based metathesis catalysts that react relatively selectively with terminal olefins to give Z homocoupled products. The most effective catalysts are W(NAr)(C[subscript 3]H[subscript 6])(pyr)(OHIPT) (Ar = 2,6-diisopropylphenyl; pyr = pyrrolide; OHIPT = O-2,6-(2,4,6-i-Pr[subscript 3]C[subscript 6]H[subscript 2])[subscript 2]C[subscript 6]H[subscript 3]) and various [CpRu(P–N)(MeCN)]X (X[superscript –] = [B(3,5-(CF[subscript 3])[subscript 2]C[subscript 6]H[subscript 3])[subscript 4][superscript –]], PF[subscript 6][superscript –], B(C[subscript 6]F[subscript 5])[subscript 4][superscript –]) isomerization catalysts.National Science Foundation (U.S.). Center for Chemical Innovation. Center for Enabling New technologies through Catalysis (Phase II Renewal. CHE-120518)National Science Foundation (U.S.) (CHE-1059107

Update of the 2014 Drought on California Rangelands

On the Ground • Droughts are common on California rangelands. • The current drought in California is listed as severe or exceptional for most of the state. • The drought has affected rangeland, and the livestock industry, more than other commodities. • The actual costs associated with this drought are just beginning to be realized.The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform March 202

Tree shelters and weed control enhance growth and survival of natural blue oak seedlings

Blue oak is regenerating poorly in portions of its range. Techniques to artificially regenerate trees by collecting acorns, growing seedlings in a nursery and then planting them are effective but costly. Improving the growth and survival rate of existing volunteer seedlings in woodlands could be more cost efficient and therefore more widely used. We tested tree shelters and weed control treatments over 3 years at six woodland sites to evaluate whether they helped blue oak seedlings grow into saplings. The tree shelters enhanced height growth, and weed control improved survival. Together, these two techniques can improve the chances for managing blue oak sustainably and conserving this native California oak for future generations

Estimating Forage Loss from California Ground Squirrels in Central California Rangelands (Abstract)

California ground squirrels (Otospermophilus spp.) cause more economic damage to California rangelands than any other rodent (Baldwin et al. 2022). Burrow systems can undermine stock pond dams, ranch roads, and even hillslopes. However, forage loss is generally the primary concern. When asked, ranchers offer detailed qualitative descriptions of the damage ground squirrels cause and how it impacts the economic viability of their operations. Damage by ground squirrels can be particularly concerning because ranching operations are often on the margins of profitability. Unfortunately, few studies have quantified economic losses from ground squirrels. Additionally, ranchers commonly lease grazing land from public agencies. In many cases, agency employees have a limited understanding of ranching operations and generally do not allow for control of ground squirrels. Quantitative data on ground squirrel impacts to rangelands and ranching operations may help land management agencies better understand the challenges faced by their lessees and justify targeted management actions in the future. Therefore, we tested the amount of standing crop removed by ground squirrels across 16 sites on the Central Coast and interior central California 2019 and 2020. Sampling was conducted during a 4 to 6-week period in May and early-June. This timeframe coincided with the period after juvenile squirrels emerged from natal dens, which allowed us to quantify the collective impact that the entire ground squirrel population had on the landscape. We included four different ground squirrel density categories per site: minimal (0-1 squirrel), low (2-6 squirrels), medium (7-15 squirrels), and high (more than 15 squirrels). To quantify ground squirrels, we counted individuals in 0.4-ha plots using binoculars from an observation point outside the plots. We conducted five ground squirrel counts, repeated twice a day over three days for a total of 30 counts per plot, and used the highest number observed in analyses. We estimated standing crop (biomass of herbaceous vegetation) using the comparative yield method. We also evaluated precipitation and livestock grazing intensity in relation to forage production. We found that each ground squirrel reduced standing crop by 27.2 kg per ha. Precipitation also influenced forage production: each cm of precipitation yielded 16.6 kg per ha of additional available forage. In our model, identified effects of livestock grazing intensity; interaction between livestock grazing intensity and ground squirrel abundance; and interaction between precipitation and ground squirrel abundance on residual standing crop were not statistically significant. Although grazing intensity does influence vegetation biomass, we did not identify a significant relationship between the two, likely because we were limited to collecting grazing intensity data at the scale of the field, not at the scale of our survey plots. Despite their economic impacts, ground squirrels are critically important to California rangeland ecosystems. Ground squirrel burrows are documented to provide habitat for native wildlife including burrowing owls (Athene cunicularia) and California tiger salamanders (Ambystoma californiense). Ground squirrel colonies are also known to be associated with increased native bird species richness, diversity, and abundance (Lenihan 2007). Because of these potential benefits to supporting native wildlife, active ground squirrel management should only be conducted on rangelands when ground squirrel damage exceeds levels considered tolerable by ranch managers. The level of damage considered intolerable will likely vary among managers of different sites. Results from this study could help ranchers and other land managers identify when such a threshold is exceede