农田开垦对三江平原湿地土壤种子库影响及湿地恢复潜力

种子库是湿地植被恢复的重要途径之一,不同时期的耕作土壤中残留的种子对开垦湿地恢复具有重要的作用.本文采用温室萌发法在两种水分条件下对三江平原天然湿地、不同开垦年限湿地种子库结构和规模进行了研究,以了解不同开垦年限湿地种子库特征及其在湿地植被恢复中的潜力.本次实验共萌发物种50种,随着开垦年限增加,萌发物种逐渐减少,天然湿地、开垦1年、3年、10年、20年的湿地分别为34种、31种、21种、21种和8种,萌发物种数与种子库规模均表现出极显著差异(F1=8.32,F2=5.946,P＜0.001).种子库密度以天然湿地和开垦1年湿地最大,分别为7624粒/m2,9836粒/m2.随着开垦年限增加,种子库规模逐渐减小,开垦3年、10年种子库密度为4336粒/m2,4872粒/m2.开垦20 a后,显著减少为432粒/m2.湿润条件下萌发物种数及种子密度显著高于淹水处理,种子库具有明显的分层现象,0-5 cm土层种子库规模显著高于5-10 cm.小叶章(Calamagrostis angustifolia)作为该地区优势物种,由最初的1192粒/m2,经过20 a开垦后在种子库中消失.研究表明,在一定的开垦年限范围内,开垦湿地土壤中仍然保留大量的湿地物种种子,在湿地恢复中具有重要的作用.     

Confounded winter and spring phenoclimatology on large herbivore ranges

Annual variation in winter severity and growing season vegetation dynamics appear to influence the demography of temperate herbivores but parsing winter from spring effects requires independent metrics of environmental conditions specific to each season. We tested for independence in annual variation amongst four common metrics used to describe winter severity and early growing season vegetation dynamics across the entire spatial distribution of elk (Cervus elaphus) in Wyoming from 1989 to 2006. Winter conditions and early growing season dynamics were correlated in a specific way. Winters with snow cover that ended early tended to be followed by early, but slow, rises in the normalized difference vegetation index (NDVI), while long winters with extended periods of snow cover were often followed by late and rapid rises in NDVI. Across the 35 elk ranges, 0.4–86.8 % of the variation in the rate of increase in NDVI’s in spring was explained by the date snow cover disappeared from SNOTEL stations. Because phenoclimatological metrics are correlated across seasons and shifting due to climate change, identifying environmental constraints on herbivore fitness, particularly migratory species, is more difficult than previously recognized.     

A veterinary perspective on methicillin-resistant staphylococci

Objective – To familiarize the reader with the epidemiology, diagnosis, and infectious and zoonotic potential of methicillin-resistant staphylococci.
Data sources – Original research publications, scientific reviews and abstracts, case reports, and conference proceedings.
Human Data Synthesis – Staphylococcus aureus is a common human commensal organism; acquisition of genes encoding an altered penicillin-binding protein confers resistance to β-lactam antimicrobial drugs. Methicillin-resistant S. aureus (MRSA) are often resistant to non–β-lactam antimicrobial drugs as well. Originally described as an important cause of nosocomial infection, MRSA colonization and infection are now often identified in humans outside healthcare settings. Like other S. aureus , MRSA may be present without clinical illness. However, when they do cause infection the consequences can be extremely serious.
Veterinary Data Synthesis – The major domestic animal species, including pets and livestock, may become contaminated, colonized, or infected with methicillin-resistant staphylococci, including MRSA. Dogs and cats are more likely to be colonized/infected with Staphylococcus pseudintermedius than S. aureus , but this pathogen can acquire genes encoding methicillin resistance (ie, MRSP). Diagnosis of MRSA or MRSP has implications not only for treatment of infected animals, but for potential zoonotic transmission.
Conclusions – MRSA infection is an important cause of morbidity and mortality in humans. Animals may be contaminated, colonized, or infected with MRSA, with implications for the animal's health and as a potential reservoir for human infection. Staphylococci other than S. aureus may also acquire genes for methicillin resistance, and these species can also result in animal and occasionally human morbidity or mortality.     

A biophysical model to assess the trade‐off between larval recruitment and catch in southern Australia's largest prawn fishery

Data from stock assessment surveys, published research and climate sensors were linked to model the interaction between fishing, physical‐oceanographic processes and spatial patterns of larval settlement for western king prawn [Penaeus (Melicertus) latisulcatus]. This information was used to evaluate the trade‐off between larval recruitment and catch during fishing periods that demand high prices but coincide with spawning. Total rates of larval settlement were maximized when tidal currents and atmospheric physical‐forcing components were coupled with simulations of larval swimming behaviour under average gulf temperatures. Average gulf temperatures sustained longer larval durations and increased larval settlement rates by over 12% compared with warmer gulf conditions simulated under a scenario of global warming. Reproductive data coupled with outputs from the biophysical model identified consistent inter‐annual patterns in the areas contributing to larval settlement success. Areas located in the north‐east, and central‐west of the fishery, consistently contributed to over 40% of all larvae reaching a settlement in each year. Harvest sensitivity analyses indicated that changes in the spatial patterns of pre‐Christmas fishing could lead to improvements in overall rates of the larval settlement while maintaining or improving the levels of catch. Future studies to refine the model inputs relating to physical processes, larval behaviour and mortality rates for P. latisulcatus coupled with surveys of juvenile prawn abundance to ground truth the modelled predictions, would allow stock recruitment relationships to be more closely examined and inform adaptive management of the fishery in the future.     

Plasma protein profiles of neonatal pigs before and after suckling

Absorption of colostral proteins ingested by neonatal piglets within 24 to 36 h after birth is generally considered to be non-selective. Nevertheless, the transfer of colostral proteins, except immunoglubulins, from gut to bloodstream after natural suckling is still poorly characterized. The purpose of this study was to investigate the changes in 2-dimensional electrophoretic plasma protein profiles of neonatal piglets before and after suckling, in order to characterize the gastrointestinal absorption of colostral proteins into the neonatal bloodstream. As expected, the most significant change in plasma after suckling is the presence of a large amount of immunoglobulin. However, while the concentration of a few proteins was mildly increased in post-suckling plasma, the evidence of absorption of colostral non-immunoglobulin proteins by neonatal piglets was not detected in this study.     

Ultrasound during mid‐gestation: Agreement with physical foetal and placental measurements and use in predicting gestational age in sheep

To determine the effects of poor maternal nutrition and litter size on foetal growth during mid‐gestation, pregnant ewes (n = 82) were fed 100%, 60% or 140% of NRC TDN beginning at day 30.2 ± 0.2 of gestation. Transabdominal ultrasound was performed weekly between day 46.0 ± 0.4 and 86.0 ± 0.7 to monitor foetal heart width (HW), umbilical diameter (UMB), rib width (RW) and placentome outer (OD) and inner diameter (ID). Data were analysed with repeated‐measures using the mixed procedure for effects of maternal diet, litter size and gestation, and equations predictive of gestational age were generated using the regression procedure. To determine the agreement of ultrasound measurement and actual size, ewes (n = 20–21) were euthanized at day 45 or 90 to obtain corresponding postmortem measurements for Bland–Altman analysis. The HW, UMB and placentome OD and ID increased with gestation (p < .0001) but were unaffected by maternal diet or litter size (p ≥ .12). Ultrasound underestimated postmortem measurements of HW (14.8%), UMB (7.3%), placentome OD (4.5%) and ID (37.3%) at day 90 of gestation. Ultrasound underestimated RW at day 45 (7.7%) but overestimated RW (23.8%) at day 90, indicating inconsistent bias when reporting RW by ultrasound. Combining the HW, UMB, RW and placentome OD generated the strongest equation predictive of gestational age (R² = .91). These findings indicate that during mid‐gestation, maternal diet or litter size did not affect HW, UMB or placentome diameters and these factors can be used to estimate gestational age.     

Allometric models for estimation of aboveground biomass of Gmelina arborea Roxb. in pulpwood plantations of Bangladesh

Gmelina arborea Roxb. is a fast-growing, deciduous tree species native to Bangladesh. It has been widely planted since 1992 for commercial production of pulpwood in hilly areas of Bangladesh. The purpose of this study was to derive well-fitting allometric models for estimation of aboveground biomass, and carbon and nutrient (nitrogen, phosphorus and potassium) stocks in G. arborea to ensure sustainable production and management of this species. Eight linear models with 64 regression equations were tested for estimation of aboveground biomass, carbon and nutrient stocks in different parts (leaves, branches, bark and stem) of the plant. The best-fitting allometric models were selected in accordance with various relevant statistical criteria.     

An overview of beef cattle improvement programs in the United States

A periodic review of beef improvement programs is useful as a benchmark and as an opportunity to reevaluate industry direction. The history of improvement programs is reviewed with particular emphasis on recording organizations, program financing, and technological progress. The various breed associations have become the primary suppliers of performance programs, which are largely funded through registration income. Current practices are described from the aspects of traits recorded and delivery systems to collect, analyze, and distribute the data. The unique or innovative features of several breed made of the organization, technical, and educational challenges facing beef improvement. Although increased participation in genetic improvement programs is expected, substantial efforts are needed to serve adequately the needs of a changing beef cattle industry.