An aboveground–belowground assessment of ecosystem properties associated with exotic annual brome invasion     

Caley K. Gasch  Stephen F. Enloe  Peter D. Stahl  Stephen E. Williams 《Biology and Fertility of Soils》2013,49(7):919-928

Exotic annual brome invasion has been well studied in western North American rangelands, particularly for Bromus tectorum L. invasion in sagebrush (Artemisia tridentata) grasslands. We examined both aboveground and belowground properties in native sagebrush grassland and adjacent areas dominated by exotic annual bromes (B. tectorum L. and Bromus japonicus Thunb.) to better understand the fundamental ecological differences between native and invaded areas. Field sites were located in north central Wyoming, USA, and plots were established in areas that had been historically subject to wildfire and either (1) recolonized by native sagebrush grassland vegetation or (2) invaded by exotic annual bromes. We employed measures of vegetation community structure as well as soil physical, chemical, and microbiological properties. Plots with greater than 20 % exotic annual brome cover had significantly less cover of all native vegetation functional groups resulting in lower richness and evenness than native plots. Invaded plots also had low diversity plant communities that were continuous and uniform across space. Soils beneath invaded plant communities had higher infiltration rates, higher levels of total nitrogen, and a lower C/N ratio than the native soils. Invaded soils also had 90–96 % lower abundance of all soil microbial groups measured by phospholipid fatty acid. We conclude that areas dominated by exotic annual bromes display different aboveground and belowground properties compared to the native community, and these changes possibly include spatial and temporal shifts in soil resources and organic matter processing.  相似文献   

Zinc nutrition affects alfalfa responses to water stress and excessive moisture     

Harsharn Singh Grewal  Rex Williams 《Journal of plant nutrition》2013,36(7):949-962

The interactive effect of applied zinc (Zn) and soil moisture on early vegetative growth of three alfalfa (lucerne) (Medicago sativa L.) varieties was investigated in a sand‐culture pot experiment to test whether there is link between Zn nutrition and soil moisture stress or excessive moisture tolerance in alfalfa plants. Three varieties (Sceptre, Pioneer L 69, and Hunterfield) with differential Zn efficiency (ability of a variety to grow and yield well in a Zn deficient soil is called a Zn‐efficient variety) were grown at two Zn levels (low Zn supply: 0.05 mg Zn kg^‐1 of soil, adequate Zn supply: 2.0 mg Zn kg^‐1 of soil) and three levels of soil moisture (soil moisture stress: 3% soil moisture on soil dry weight basis; adequate soil moisture: 12% soil moisture on soil dry weight basis; excessive soil moisture: 18% soil moisture on soil dry weight basis) in a Zn deficient (DTPA Zn: 0.06 mg kg^‐1 soil) siliceous sand. Zinc treatments were applied at planting, while soil moisture treatments were applied three weeks after planting and continued for two weeks. Plants were grown in pots under controlled temperature conditions (20°C, 12 h day length; 15°C, 12 h night cycle) in a glasshouse. Plants grown at low Zn supply developed Zn deficiency symptoms, and there was a severe solute leakage from the leaves of Zn‐deficient plants. Adequate Zn supply significantly enhanced the leaf area, leaf to stem ratio, biomass production of shoots, and roots, succulence of plants and Zn concentration in leaves. At low Zn supply, soil moisture stress and excessive moisture treatments significantly depressed the shoot dry matter, leaf area and leaf to stem ratio of alfalfa plants, while there was little impact of soil moisture treatments when supplied Zn concentration was high. The detrimental effects of soil moisture stress and excessive soil moisture under low Zn supply were less pronounced in Sceptre, a Zn‐efficient alfalfa variety compared with Hunterfield, a Zn‐inefficient variety. Results suggest that the ability of alfalfa plants to cope with water stress and excessive soil moisture during early vegetative stage was enhanced with adequate Zn nutrition.  相似文献   

Can spinosad be effective for the integrated management of Anastrepha ludens (Tephritidae) in soil and fallen fruit,and be compatible with the parasitoid Diachasmimorpha longicaudata (Braconidae)?     

Williams  Trevor  Mercado  Gabriel  Aluja  Martín 《Phytoparasitica》2021,49(1):73-82

Phytoparasitica - Tephritid fruit flies are susceptible to insecticide treatments when leaving infested fruit to pupate in the soil and when emerging as adults. Laboratory experiments involved...  相似文献   

An Evaluation of Rabies Vaccination Rates among Canines and Felines Involved in Biting Incidents within the Wellington–Dufferin–Guelph Public Health Department     

K. Bottoms  L. Trotz‐Williams  S. Hutchison  J. MacLeod  J. Dixon  O. Berke  Z. Poljak 《Zoonoses and public health》2014,61(7):499-508

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The transmissible spongiform encephalopathies: disease risks for North America.     

Elizabeth S Williams 《Veterinary Clinics of North America: Food Animal Practice》2002,18(3):461-473

Transmissible spongiform encephalopathies exotic to North America (BSE and associated diseases) are unlikely to be introduced or to persist should they be introduced into the United States [2]. Domestic TSEs (scrapie, CWD, and TME) seem to be relatively restricted in their host range, and none of these diseases is known to naturally cause disease in cattle. It is important that surveillance for TSEs continues, however, particularly in cattle because of the extreme consequences to the livestock industries, and potentially, public health, if BSE becomes established. Because the TSEs have implications beyond effects on their natural host species, adequate surveillance, control, and even eradication of these diseases should be goals for the livestock industries, wildlife managers, and animal health agencies in the United States.  相似文献   

Comparison of digital image analysis using elliptic Fourier descriptors and major dimensions to phenotype seed shape in hexaploid wheat (Triticum aestivum L.)     

Keith Williams  Jesse Munkvold  Mark Sorrells 《Euphytica》2013,190(1):99-116

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Developing Sources of Native Grass Seed for Revegetation in Florida     

Mary J. Williams  Janet Grabowski  Brandee Williams 《Herpetological Monographs》2013,35(5):93-97

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Persistent efficacy and production benefits following use of extended-release injectable eprinomectin in grazing beef cattle under field conditions     

B.N. Kunkle  J.C. Williams  E.G. Johnson  B.E. Stromberg  T.A. Yazwinski  L.L. Smith  S. Yoon  L.G. Cramer 《Veterinary parasitology》2013

Seven studies were conducted in commercial grazing operations to confirm anthelmintic efficacy, assess acceptability, and measure the productivity response of cattle to treatment with eprinomectin in an extended-release injectable formulation (ERI) when exposed to nematode infected pastures for 120 days. The studies were conducted under one protocol in the USA in seven locations (Arkansas, Idaho, Louisiana, Minnesota, Missouri, Oregon, and Wisconsin). Each study had 67–68 naturally infected animals for a total of 475 (226 female, 249 male castrate) Angus or beef-cross cattle. The animals weighed 133–335 kg prior to treatment and were approximately 3–12 months of age. The studies were conducted under a randomized block design based on pre-treatment body weights to sequentially form 17 replicates of four animals each within sex in each study. Animals within a replicate were randomly assigned to treatments, one to Eprinomectin ERI vehicle (control) and three to Eprinomectin ERI (5%, w/v eprinomectin). Treatments were administered at 1 mL/50 kg body weight once subcutaneously anterior to the shoulder. All animals in each study grazed one pasture throughout the observation period of 120 days. Cattle were weighed and fecal samples collected pre-treatment and on 28, 56, 84, and 120 days after treatment for fecal egg and lungworm larval counts. Positive fecal samples generally were cultured en masse to determine the nematode genera attributable to the gastrointestinal helminth infection. Bunostomum, Cooperia, Haemonchus, Nematodirus, Oesophagostomum, Ostertagia, and Trichostrongylus, when present, were referred to as strongylids. At all post-treatment sampling intervals, Eprinomectin ERI-treated cattle had significantly (P < 0.05) lower strongylid egg counts than vehicle-treated controls, with ≥95% reduction after 120 days of grazing. Over this same period, Eprinomectin ERI-treated cattle gained more weight (43.9 lb/head) than vehicle-treated controls in all studies. This weight gain advantage was significant (P < 0.05) in six of the studies with the Eprinomectin ERI-treated cattle gaining an average of 42.8% and the control cattle gaining 33.1% of their initial weight. No adverse reactions were observed in the treated animals.  相似文献   

Dietary and Manure Management Practices on Equine Farms in Two New Jersey Watersheds     

Michael L. Westendorf  Venkata Puduri  Carey A. Williams  Troy Joshua  Ramu Govindasamy 《Journal of Equine Veterinary Science》2013

Equine farms are increasing in number in Northeast and Mid-Atlantic states. These farms may influence environmental quality owing to manure collection, storage, spreading, and disposal practices. A manure management survey was mailed to 700 New Jersey equine farms during the winter of 2009-2010 (these farms were located in two watersheds). Two hundred forty-two surveys were returned; 10% were training or performance farms, whereas the remainder (90%) were breeding, boarding, or pleasure farms. There were differences between the two watersheds in turnout time, pasture acreage, use of drag harrows, and income. Respondents answered questions about diet and environmental management on farms. Seventy-eight percent had bunk management plans. Forty-seven percent disposed of waste feed in a manure pile, 35% left it on fields or paddocks, and 18% put it in a dumpster. Twenty-six percent engage a professional for feeding advice (21% veterinarians, 2% extension, 3% nutrition consultants). Most respondents did not have a regular feed management plan. Sixty-two percent of all farms spread manure on-farm. Of those who spread, 29% have >8.09 hectares (20 acres) for spreading. Ninety-six percent of respondents stored manure >100 ft from water or wetlands. Comparison of cross-tabulations indicates a strong relationship (P < .01) between rotational grazing and the use of a sacrifice or exercise area. Eighty-eight percent of respondents using sacrifice areas also rotationally graze. Results indicate future outreach programs should focus on feed management, manure storage location, rotational grazing, and the use of sacrifice areas as part of a pasture management program.  相似文献   

Comparison of three markers for the determination of bacterial protein in terminal ileal digesta in the growing pig     

W. Miner‐Williams  P. J. Moughan  M. F. Fuller 《Journal of animal physiology and animal nutrition》2013,97(5):951-959

The aim of the study was to compare three methods commonly used to determine the concentrations of bacterial protein in digesta collected from the terminal ileum of growing pigs that had been fed a casein‐based diet. The amounts of bacterial protein in terminal ileal digesta were determined using three different markers: 2.6‐diaminopimelic acid (DAPA) and the d ‐amino acids, d ‐aspartic acid (d ‐Asp) and d ‐glutamic acid (d ‐Glu). The effectiveness of each marker was compared against a control based on physical fractionation by centrifugation. The total bacterial protein concentrations derived from the markers d ‐Asp and d ‐Glu were significantly different (p = 0.05) to those calculated from DAPA and the control, but there was no difference between DAPA and the control. The percentage of bacterial nitrogen ranged from 40% to 52% dependent on the marker used. Bacterial protein expressed as a percentage of the total protein, ranged from 48% to 62%, a substantial proportion of which (12–28%) was derived from lysed bacterial cells. Statistical correlations between the estimation methods were low. Such poor correlation between the markers may be the result of random errors such as variance in the epimerization of the two d ‐amino acids during protein hydrolysis. DAPA was accepted as a reliable marker for determining microbial protein in ileal digesta.  相似文献