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661.
Abstract The False Thornveld of the Eastern Cape experienced a particularly intense drought during the 1982/83 growing season. Extensive grass mortality took place during the drought. After the drought, recovery was particularly sensitive to the post‐drought management treatment applied. Veld that was grazed immediately after the drought recovered far more slowly than veld that was rested. This effect was still evident three years later, illustrating the considerable importance of resting semi‐arid grassveld after a drought. Increaser I grass species present were apparently more capable of surviving drought than the Decreaser species, which in turn were more stable than the Increaser II species. Their ability to recover after the drought followed an opposite trend. On this basis, the desirability of Decreaser dominated veld, in situations that are likely to be poorly managed, is questioned. 相似文献
662.
663.
Abstract Madam:— In October 1984 the Ministry of Agriculture and Fisheries (MAF) opened a voluntary scheme to accredit flocks free from caprine arthritis encephalitis (CAE). (1) The scheme was designed in consultation with the New Zealand Goat Council and the Council of the New Zealand Veterinary Association. 相似文献
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Tim Morris Stuart W. Paine Paul Zahra Eric Li Sally Colgan Steven Karamatic 《Journal of veterinary pharmacology and therapeutics》2019,42(5):505-510
Medication control in greyhound racing requires information from administration studies that measure drug levels in the urine as well as plasma, with time points that extend into the terminal phase of excretion. To characterize the plasma and the urinary pharmacokinetics of flunixin and enable regulatory advice for greyhound racing in respect of both medication and residue control limits, flunixin meglumine was administered intravenously on one occasion to six different greyhounds at the label dose of 1 mg/kg and the levels of flunixin were measured in plasma for up to 96 hr and in urine for up to 120 hr. Using the standard methodology for medication control, the irrelevant plasma concentration was determined as 1 ng/ml and the irrelevant urine concentration was determined as 30 ng/ml. This information can be used by regulators to determine a screening limit, detection time and a residue limit. The greyhounds with the highest average urine pH had far greater flunixin exposure compared with the greyhounds that had the lowest. This is entirely consistent with the extent of ionization predicted by the Henderson–Hasselbalch equation. This variability in the urine pharmacokinetics reduces with time, and at 72 hr postadministration, in the terminal phase, the variability in urine and plasma flunixin concentrations are similar and should not affect medication control. 相似文献
666.
Rebecca E. Hewitt Alec P. Bennett Amy L. Breen Teresa N. Hollingsworth D. Lee Taylor F. Stuart ChapinIII T. Scott Rupp 《Landscape Ecology》2016,31(4):895-911
Context
Forecasting the expansion of forest into Alaska tundra is critical to predicting regional ecosystem services, including climate feedbacks such as carbon storage. Controls over seedling establishment govern forest development and migration potential. Ectomycorrhizal fungi (EMF), obligate symbionts of all Alaskan tree species, are particularly important to seedling establishment, yet their significance to landscape vegetation change is largely unknown.Objective
We used ALFRESCO, a landscape model of wildfire and vegetation dynamics, to explore whether EMF inoculum potential influences patterns of tundra afforestation and associated flammability.Methods
Using two downscaled CMIP3 general circulation models (ECHAM5 and CCCMA) and a mid-range emissions scenario (A1B) at a 1 km2 resolution, we compared simulated tundra afforestation rates and flammability from four parameterizations of EMF effects on seedling establishment and growth from 2000 to 2100.Results
Modeling predicted an 8.8–18.2 % increase in forest cover from 2000 to 2100. Simulations that explicitly represented landscape variability in EMF inoculum potential showed a reduced percent change afforestation of up to a 2.8 % due to low inoculum potential limiting seedling growth. This reduction limited fuel availability and thus, cumulative area burned. Regardless of inclusion of EMF effects in simulations, landscape flammability was lower for simulations driven by the wetter and cooler CCCMA model than the warmer and drier ECHAM5 model, while tundra afforestation was greater.Conclusions
Results suggest abiotic factors are the primary driver of tree migration. Simulations including EMF effects, a biotic factor, yielded more conservative estimates of land cover change across Alaska that better-matched empirical estimates from the previous century.667.
Maxwell C. Wilson Xiao-Yong Chen Richard T. Corlett Raphael K. Didham Ping Ding Robert D. Holt Marcel Holyoak Guang Hu Alice C. Hughes Lin Jiang William F. Laurance Jiajia Liu Stuart L. Pimm Scott K. Robinson Sabrina E. Russo Xingfeng Si David S. Wilcove Jianguo Wu Mingjian Yu 《Landscape Ecology》2016,31(2):219-227
668.
Maxwell C. Wilson Xiao-Yong Chen Richard T. Corlett Raphael K. Didham Ping Ding Robert D. Holt Marcel Holyoak Guang Hu Alice C. Hughes Lin Jiang William F. Laurance Jiajia Liu Stuart L. Pimm Scott K. Robinson Sabrina E. Russo Xingfeng Si David S. Wilcove Jianguo Wu Mingjian Yu 《Landscape Ecology》2016,31(2):229-230
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670.