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61.
Interpreting the dependence of soil respiration on soil temperature and water content in a boreal aspen stand 总被引:10,自引:2,他引:8
David Gaumont-Guay T. Andrew Black Tim J. Griffis Alan G. Barr Rachhpal S. Jassal Zoran Nesic 《Agricultural and Forest Meteorology》2006,140(1-4):220
Continuous half-hourly measurements of soil CO2 efflux made between January and December 2001 in a mature trembling aspen stand located at the southern edge of the boreal forest in Canada were used to investigate the seasonal and diurnal dependence of soil respiration (Rs) on soil temperature (Ts) and water content (θ). Daily mean Rs varied from a minimum of 0.1 μmol m−2 s−1 in February to a maximum of 9.2 μmol m−2 s−1 in mid-July. Daily mean Ts at the 2-cm depth was the primary variable accounting for the temporal variation of Rs and no differences between Arrhenius and Q10 response functions were found to describe the seasonal relationship. Rs at 10 °C (Rs10) and the temperature sensitivity of Rs (Q10Rs) calculated at the seasonal time scale were 3.8 μmol m−2 s−1 and 3.8, respectively. Temperature normalization of daily mean Rs (RsN) revealed that θ in the 0–15 cm soil layer was the secondary variable accounting for the temporal variation of Rs during the growing season. Daily RsN showed two distinctive phases with respect to soil water field capacity in the 0–15 cm layer (θfc, 0.30 m3 m−3): (1) RsN was strongly reduced when θ decreased below θfc, which reflected a reduction in microbial decomposition, and (2) RsN slightly decreased when θ increased above θfc, which reflected a restriction of CO2 or O2 transport in the soil profile.Diurnal variations of half-hourly Rs were usually out of phase with Ts at the 2-cm depth, which resulted in strong diurnal hysteresis between the two variables. Daily nighttime Rs10 and Q10Rs parameters calculated from half-hourly nighttime measurements of Rs and Ts at the 2-cm depth (when there was steady cooling of the soil) varied greatly during the growing season and ranged from 6.8 to 1.6 μmol m−2 s−1 and 5.5 to 1.3, respectively. On average, daily nighttime Rs10 (4.5 μmol m−2 s−1) and Q10Rs (2.8) were higher and lower, respectively, than the values obtained from the seasonal relationship. Seasonal variations of these daily parameters were highly correlated with variations of θ in the 0–15 cm soil layer, with a tendency of low Rs10 and Q10Rs values at low θ. Overall, the use of seasonal Rs10 and Q10Rs parameters led to an overestimation of daily ranges of half-hourly Rs (ΔRs) during drought conditions, which supported findings that the short-term temperature sensitivity of Rs was lower during periods of low θ. The use of daily nighttime Rs10 and Q10Rs parameters greatly helped at simulating ΔRs during these periods but did not improve the estimation of half-hourly Rs throughout the year as it could not account for the diurnal hysteresis effect. 相似文献
62.
REASONS FOR PERFORMING STUDY: An alternative technique of radiographing the pelvis in the standing horse is required, to avoid the risks associated with general anaesthesia. HYPOTHESIS: That lateral oblique radiography in the standing horse would be a useful technique in the investigation of pelvic injury. OBJECTIVES: To describe the technique of lateral oblique pelvic radiography in the standing horse and demonstrate the feasibility and usefulness of this technique. METHODS: A technique for lateral oblique radiography in the standing horse was devised and retrospective review made of radiographic findings in 18 clinical cases. RESULTS: The caudal iliac shaft, greater trochanter of the femur, femoral head, acetabulum and coxofemoral articulation on the side under investigation were visualised consistently using this technique. Of the 18 cases, 3 iliac shaft fractures, 1 acetabular fracture, 2 coxofemoral luxations and 4 horses with new bone formation around the coxofemoral joint and/or proximal femur were identified. CONCLUSIONS: Lateral oblique radiography in the standing, conscious horse can be used to investigate conditions affecting the caudal iliac shaft, coxofemoral articulation and proximal femur in the horse. POTENTIAL RELEVANCE: The technique is straightforward, noninvasive and useful in the investigation of horses with suspected pelvic injury. However, not all pelvic injuries would be identified, and normal radiographic findings do not rule out injury or fractures elsewhere in the pelvis. 相似文献
63.
Gasper D Barr B Li H Taus N Peterson R Benjamin G Hunt T Pesavento PA 《Veterinary pathology》2012,49(3):492-497
A private zoological facility experienced an outbreak of malignant catarrhal fever (MCF) in 3 bongo antelope (Tragelaphus eurycerus). All cases were periparturient bongos that presented acutely anorectic beginning ~6 weeks after being housed with a Nubian ibex. Disease quickly progressed to respiratory distress and death within 24-72 hours of onset of clinical signs. Consistent gross findings in affected bongos were pulmonary edema and small pale tan foci in the livers. Histological lesions included a nonsuppurative vasculitis in multiple tissues, which is well recognized in MCF, but additionally included necrotizing cholangiohepatitis and neutrophilic, necrotizing myocarditis. Ibex-associated viral DNA was detected by polymerase chain reaction and was identical in sequence whether derived from bongos or ibex. The sequence closely matched an MCF viral DNA fragment that had been amplified from an ibex and bongo in a previous case report. 相似文献
64.
Congenital abnormalities of the reproductive tract of male sheep were surveyed at three abattoirs in the south west of England during the period June 2000-January 2004. A total of 7307 rams were examined [6521 lambs (prepubescent) and hoggets (aged from their first autumn after birth until first shorn) and 786 adult rams mature rams that had been exposed to ewes]. A total of 156 congenital lesions were detected, 87 of which occurred in lambs. Testicular hypoplasia was the most common lesion occurring in 69 lambs as well as eight hoggets ('microtestes' were recognized in nine other animals in which the testis was disproportionately smaller than the epididymis). The second most common lesion found was notched scrotum occurring in 34 animals (27 young rams and seven adults). Some cases of notched scrotum were accompanied by hypospadias which was seen in a total of seven lambs and eight hoggets. Other lesions, detected in five or less animals (less than approximately 0.05% of the animals examined), included cryptorchidism and various abnormalities of the epididymis (segmental aplasia of the epididymis, blind efferent ducts and epididymal cyst) and congenital scrotal hernia. The overall prevalence of congenital lesions of 2.21% emphasizes the importance of undertaking breeding soundness examinations of young rams before they are put with the flock. 相似文献
65.
Barrère V Alvarez L Suarez G Ceballos L Moreno L Lanusse C Prichard RK 《Veterinary parasitology》2012,186(3-4):344-349
Resistance to benzimidazole anthelmintics in the nematode Haemonchus contortus has been correlated with single nucleotide polymorphisms (SNPs) on the β-tubulin isotype 1 gene. Three mutations can be used as markers for the detection of resistance, namely SNPs at position 200 and 167 (both TTC to TAC) or at position 198 (GAA to GCA). Harbouring a resistance genotype at any one of these codons can lead to a resistant phenotype. Our objective in this study was to analyse the frequencies of the three mutations when the albendazole dose rate and selection pressure were increased. We used adult H. contortus (males and females) collected directly from the abomasum of untreated lambs, or lambs treated with the manufacturer's recommended dose rate (5mg/kg), three times the recommended dose rate (15 mg/kg), or nine times the recommended dose rate (45 mg/kg). Anthelmintic efficacy was determined by worm and egg count reductions. For the surviving worms of the four treatment groups, the frequencies of each resistance SNP at codons 167, 200 and 198 were measured using pyrosequencing. Our results showed a strong relationship between an increasing dose rate and an increase in the frequency of the (TAC)(200) SNP and a decrease in the (TAC)(167) SNP. All worms genotyped were GAA at codon 198. 相似文献
66.
67.
Lorenza Pacini Felipe Yunta Arwyn Jones Luca Montanarella Pierre Barrè Sergio Saia Songchao Chen Calogero Schillaci 《European Journal of Soil Science》2023,74(4):e13391
Soil Bulk Density (BD) is an extremely important variable because it is an important site characterization parameter, and it is highly relevant for policy development because it is mandatory for calculating soil nutrient stocks. BD can influence soil chemical properties, land-use planning and agronomic management. The 2018 Land Use and Coverage Area Frame Survey (LUCAS) saw the unprecedented collection of BD core analysis in a subset of the locations in Europe and the United Kingdom where soil physical and chemical properties were analysed in the 2009 and the 2015 sampling campaigns. Here, we integrated the LUCAS 2018 BD sampling campaign with the mass fraction of coarse fragments previously determined in LUCAS 2009–2015 in order to provide a dataset of the volume fraction of coarse fragments and the BD of the fine earth and improve soil organic carbon (SOC) stock estimation accuracy for topsoil. BD data sampled at 0–10 and 10–20 cm were averaged to harmonize the BD with the mass fraction of coarse fragments measured in 2009, 2012 and 2015. Samples were from cropland, grassland and woodland soils, which accounted for 41%, 21% and 30%, respectively, of the total number of selected sites (n = 6059); ‘bareland’, and ‘shrubland’ accounted for 3% of the sites each, whereas ‘artificial land’ accounted for <1%. Only six samples were classified as ‘wetland’. The dataset was produced assuming the mass density of the coarse fraction to be constant across all LUCAS soil samples. We also estimated the SOC stocks associated with LUCAS 2018 BD and SOC content measurements and showed that correcting the BD by the coarse mass fraction instead of the coarse volume fraction generates SOC stock underestimation. We found the highest deviations in woodlands and shrublands. We showed that, when SOC stock is computed with coarse mass fraction, the error compared with the computation by volume may vary depending on the SOC and coarse mass fraction. This may imply a SOC stock underestimation for European soils. This dataset fits into the big framework of LUCAS soil properties monitoring and contributes both to soil awareness and soil research and assessments, which are two important objectives of the Soil Strategy and the European Soil Observatory (EUSO). 相似文献
68.
69.
70.
James W. Barr III DVM S. Anna Pesillo-Crosby VMD DACVECC 《Journal of Veterinary Emergency and Critical Care》2008,18(3):270-276
Objective: To determine a reference interval of whole blood and plasma osmolalities for dogs using the Advanced Micro Osmometer Model 3300, to compare calculated osmolarity to measured osmolality, to determine a reference osmole gap, and to determine the best formula for calculated osmolaity. Design: Prospective, observational. Setting: Tertiary referral and teaching hospital. Animals: One hundred healthy adult dogs. Interventions: None. Measurements: Serum and whole blood biochemistry and osmolality assessments. Results: The mean and median of the measured whole blood osmolality were 323 and 320 mOsm/kg, respectively, with a standard deviation of 13.2 mOsm/kg. The mean and median of the measured plasma osmolality were 313 and 310 mOsm/kg, respectively, with a standard deviation of 13.2 mOsm/kg. The formula that was closest to predicting the measured whole blood and plasma osmolality was ((1.86(Na+K))+(BUN/2.8)+(Glucose/18))/0.93 followed closely by the traditional formula of (2(Na+K))+(BUN/2.8)+(Glucose/18). The mean calculated osmolarities using these formulas were 314.1 and 313.25 mOsm/L, respectively. The mean osmole gap using these formulas was 3.49 and 4.41 mOsm, respectively, for whole blood and ?2.01 and ?1.1 mOsm, respectively, for plasma. Conclusion: The Advanced Micro Osmometer Model 3300 was successful in measuring the osmolality in relative agreement with the current published reference intervals for osmolality. Measured osmolality correlated well with traditional calculated osmolarity. 相似文献