Land-Use Legacies and Vegetation Recovery 90 Years After Cultivation in Great Basin Sagebrush Ecosystems

Agricultural land use is known to alter ecological processes, and native plant communities can require decades to centuries to recover from the disturbance of cultivation. “Recovery” is typically measured by comparison to undisturbed adjacent sites as a control. Recovery following cultivation in sagebrush ecosystems of the Great Basin remains largely unexamined even though nearly a half million hectares of land were dry-farmed and abandoned in the early 1900s. We tested the hypothesis that the native vegetation has not recovered from this exotic disturbance by evaluating differences in canopy cover of shrubs, grasses, and forbs between paired sets of historically dry-farmed land and adjacent never-cultivated areas. Paired sites were located in three ecological sites in northwestern Utah. We found that vegetation recovery from cultivation is variable by growth form, species, and ecological site. Shrub recovery was different among sagebrush (Artemisia) species. Yellow rabbitbrush (Chrysothamnus viscidiflorus [Hook.] Nutt.) and black greasewood (Sarcobatus vermiculatus [Hook.] Torr.), which often increase following disturbance, maintained higher cover inside old fields. At one of the paired sets, shrub composition was altered from a mix of four species to dominance of mainly Wyoming big sagebrush (Artemisia tridentata Nutt. subsp. wyomingensis Beetle & Young). Total forb cover was generally lower in cultivated areas and some species, such as spiny phlox (Phlox hoodii Richardson), had not recovered. The most common grass species encountered across all ecological sites, bottlebrush squirreltail (Elymus elymoides [Raf.] Swezey), had higher cover in cultivated areas. Surprisingly, exotic annual species, such as cheatgrass (Bromus tectorum L.), did not dominate these sites as they have for decades after cultivation in other areas of the Great Basin. This study demonstrates that the land-use legacy of dry farming on vegetation remains nearly a century after cultivation has ceased, and has direct implications for describing ecological site conditions.     

Carriage of methicillin-resistant Staphylococcus aureus by veterinarians in Australia

Objective To estimate the prevalence of carriage of methicillin‐resistant Staphylococcus aureus (MRSA) among Australian veterinarians. Methods Individuals attending veterinary conferences in Australia in 2009 were recruited to provide nasal swabs and complete a questionnaire about their professional activities. Swabs were processed by standard methods for detecting MRSA and questionnaire responses were used to group veterinarians according to their areas of major work emphasis (species and practice type). Prevalence was estimated for each of these grouping and contingency tables and regression tree analysis used to explain the variation in MRSA carriage. Results Among the 771 respondents ‘industry and government veterinarians’ (controls) had the lowest prevalence of MRSA carriage at 0.9%. Veterinarians with horses as a major area of work emphasis had a prevalence of 11.8% (13‐fold that of controls) and those whose only major emphasis was horses had a prevalence of 21.4% (23‐fold that of controls). Veterinarians with dogs and cats as a major activity had a 4.9% prevalence (5‐fold that of controls). Prevalence rates for other major activities (pigs, dairy and beef cattle, avian and wildlife) were also increased, but were estimated from smaller numbers of respondents. Regression tree analysis clearly isolated equine veterinarians and dog and cat practitioners as groups at increased risk of carriage of MRSA. Conclusion Carriage of MRSA is a notable occupational health issue for veterinarians in clinical practice in Australia, particularly those who work with horses.     

Co-oximetry in clinically healthy dogs and effects of time of post sampling on measurements

Objectives : Co‐oximetry is a complex and valuable laboratory method that measures haemoglobin species and oxygenation status by multi‐wavelength spectrophotometry. The purpose of this study was to establish reference intervals for clinically healthy dogs and to determine the effect of time of analyses and sex of animals on the accuracy of results. Methods : Blood was collected from 27 healthy adult dogs of various breeds and sex. Co‐oximetry was performed on a CCX co‐oximeter that measures eight haemoglobin and oxygen transport related parameters: carboxyhaemoglobin (COHb), deoxyhaemoglobin (HHb), oxyhaemoglobin (O₂Hb), methaemoglobin (MetHb), total haemoglobin (tHb), oxygen saturation (SO₂%), oxygen content (O₂Ct) and oxygen capacity (O₂Cap). Results : Results obtained after 2 and 4 hours were not significantly different from those obtained immediately after sampling. But after 48 hours, the results for total haemoglobin, oxygen saturation, oxyhaemoglobin, oxygen content and oxygen capacity were significantly lower, and carboxyhaemoglobin and deoxyhaemoglobin values were significantly higher than determination immediately after sampling. Gender had no significant impact on co‐oximetry values. Clinical Significance : Co‐oximetry offers several advantages compared with other methods, including ease of use, increased accuracy and greater differentiation among haemoglobin species.     

Wheat Arabinoxylan Structure Provides Insight into Function

Recent attention to dietary fiber in wheat (Triticum aestivum L.) has invigorated research in the nonstarch carbohydrate arabinoxylan (AX). AX molecules are composed of a linear xylose backbone with arabinose substitutions along the backbone. These arabinose substituents can also carry a ferulic acid moiety. AX molecules can be fractionated into two categories based on extraction properties that have a structural and conformational basis: water‐extractable (WEAX) and water‐unextractable (WUAX) molecules. The ferulic acid moieties also allow for oxidative cross‐linking between AX molecules or the tyrosine residues of proteins. The contents of total AX and WEAX molecules are primarily influenced by genetic differences; however, there is also evidence of environmental influence on content. There are several useful methods for quantifying AX molecules, providing varying levels of structural information as well as accuracy and precision. The high water‐absorption capacity of AX molecules results in a strong influence of AX on end‐use quality. Whereas WEAX molecules, in particular, tend to be detrimental for the quality of soft wheat products such as cookies, WEAX molecules are beneficial to the quality of hard wheat products such as bread. The role of WUAX molecules among the range of soft wheat products is as yet unclear; however, WUAX molecules tend to have a detrimental influence on bread. Because of the variable influence of AX structure on end‐use product functionality, closer examination of structure–function relationships may provide key insights into how to direct breeding efforts to maximize these relationships between AX molecules and other ingredients. Further investigation is necessary to obtain a more complete understanding of how the arabinose substitution levels and patterns affect end‐use quality and how the genetic basis of these traits can be resolved and manipulated for optimum end‐use quality.     

新疆木灵藓属Orthotrichum Hedw.植物的分类学研究

根据历年采自新疆各地区的350号木灵藓属Orthotrichum 植物标本,在查阅大量文献的基础上,通过经典分类学方法,对新疆木灵藓属植物进行了整理、鉴定和分类。结果表明：新疆有木灵藓属植物5亚属、17种,包括裸孔亚属subg. Gymnoporus (6种) 、直叶亚属subg. Orthophyllum (1种)、疣叶亚属subg. Pulchella (5种)、圆孔亚属subg. Phaneroporum (1种)、木灵藓亚属subg. Orthotrichum (4种),其中高山木灵藓Orthotrichum alpestre Hornsch. ex B.S.G为中国新记录种;中国木灵藓O. hookeri Wils. ex Mitt.、东亚木灵藓O. ibukiense Toy.、短丛木灵藓O. pumilum Sw. 和卷叶木灵藓O. revolutum C. Muell. 为新疆新记录种。通过对新疆新记录种的生境、识别特征、采集地点、地理分布、海拔等信息的整理分析,绘制了4个种的线条图,并编制了新疆木灵藓属植物的分亚属和分种检索表。     

Showy partridge pea [Chamaecrista fasciculata (Michx.) Greene] with potential for cultivation as a multi-functional species in the United States

Showy partridge pea, Chamaecrista fasciculata is used in the USA for cover cropping, ornate flowers in native gardens, honey crop, as an annual reseeding legume for restoration and conservation plantings, and wildlife food. However, its greatest potential may be as a bio-control plant for the control of mole crickets, cactus moth, and additional pest species. The United States Department of Agriculture, Agricultural Research Service, Plant Genetic Resources Conservation Unit (USDA, ARS, PGRCU) conserves 36 accessions originating from the USA.     

A Critical Assessment of the Quantification of Wheat Grain Arabinoxylans Using a Phloroglucinol Colorimetric Assay

Arabinoxylans (AX) of wheat (Triticum aestivum L.) play a critical role in processing, end‐use quality, and human health and nutrition. Consequently, an efficient, accurate method of AX quantification is desirable. The objective of this work was to evaluate a standard phloroglucinol colorimetric method for quantification of wheat AX. The method is based on the formation and spectrophotometric quantification of a phloroglucide product that results from the reaction of furfural produced during the condensation of pentose sugars with phloroglucinol. Method parameters, including reaction reagents and reaction times, were varied to identify areas for improved accuracy and consistency. Phloroglucide formation at three xylose concentrations was examined over time. The optimal reaction reagents and reaction times were determined based upon improved consistency in xylose quantification. The optimized method was used on xylose and arabinose standards and on whole meal wheat samples for total and water‐extractable AX content. Glucose was shown to be unnecessary in the reaction and was eliminated. A second‐order polynomial equation provided a slightly better fit to the nearly linear standard xylose curve. A reduced concentration of phloroglucinol of 10% was found to give equivalent results to the standard 20%. Optimum reaction time was 25 min, and it required the inclusion of all reagents. The phloroglucide product decreased in absorbance over time such that, within the range of xylose concentration examined, about 40–50% of the colored product was lost over 100 min; however, the rate of loss was linear over time. Four operators performed the optimized method on whole wheat meal samples for total and water‐extractable AX. Inter‐ and intraoperator variation was identified as an area requiring further study and improvement. However, all operators tended to rank the samples in a consistent manner. Compared with a gas chromatography–flame ionization detection method, the phloroglucinol method underestimated total AX by about 2.3% and water‐extractable AX by about 0.08%.     

The effect of defoliation and competition on the regrowth of Themeda triandra and Aristida junciformis subsp. junciformis

Abstract

The effects of a cutting trial, conducted to study the combined influence of defoliation and competition from surrounding vegetation on the vigour of Themeda triandra and Aristida junciformis, were evident after the single season of treatment implementation. Aristida junciformis was more sensitive to defoliation than T. triandra, whereas competition reduced yield to a greater extent in T. triandra than in A. junciformis. The two species differed in their ability to tolerate defoliation under competition. Defoliation reduced the yield of A. junciformis, at all levels of competition, to a greater extent than T. triandra. Aristida junciformis was particularly sensitive to a combination of severe defoliation and full competition. It is suggested that manipulation of grazing patterns may shift the competitive balance between palatable (e.g. T. triandra) and unpalatable (e.g. A. junciformis) components of the sward.