Do incremental increases of the herbicide glyphosphate have indirect consequences for spider communities?

We examined the indirect effect of the herbicide glyphosate on field margin spider communities.We found that species turnover and cluster variation did not differ significantly between treatments. We attribute the lack of any effect to a large number of common agricultural species which are never eliminated from a habitat, but are instead significantly reduced. This within-season species turnover is related to the decline in vegetation height and the increase in percentage dead vegetation cover in the field margin

Providing the evidence base for environmental risk assessments of novel farm management practices

An environmental risk assessment of a new agricultural management practice depends upon the provision of empirical evidence of cause and effect. This will invariably be derived from comparative experiments testing the null hypothesis that a change in management will have no effect on an assessment endpoint (the metric on which policy decisions will be based). Crucial to the design of these experiments is the answer to the question of 'what to measure?'. The selection of these measurement endpoints and the design of sampling protocols will be determined by the properties of the environmental stressors associated with the change in management practice and the taxa that are exposed to their effects, as well as logistic and financial considerations. The rationale for deciding what to measure in the context of these various criteria is reviewed. For a measurement endpoint to be a valid indicator of the risk of a negative impact of management on the assessment endpoint, a predictable and quantifiable link must be made between the two. It should also be recorded at the appropriate taxonomic resolution to safely assume that all the constituent parts will both respond in a similar way to the management stressor and have a similar effect on the assessment endpoint. Protocols must be designed with the spatial and temporal properties of the management stressor and the measurement endpoint in mind and a consideration of the statistical power of the experiment to detect changes. Where there is a lag in the response time of a measurement endpoint to a stressor due to inertia in the system, an accurate measurement of the effect of the novel management may require experiments running over several years. Throughout, care must be taken that the statistical and biological validity of a sampling regime is not compromised in the face of logistic and financial pressures. The Farm Scale Evaluations of the management of Genetically Modified Herbicide Tolerant crops are presented as a case study to illustrate the concepts discusse

The feasibility of modal testing for the measurement of the dynamic characteristics of goat vertebral motion segments

AbstractStructural vibration testing might be a promising method to study the mechanical properties of spinal motion segments as an alternative to imaging and spinal manipulation techniques. Structural vibration testing is a non-destructive measurement technique that measures the response of a system to an applied vibration as a function of frequency, and allows determination of modal parameters such as resonance frequencies (ratio between stiffness and mass), vibration modes (pattern of motion) and damping. The objective of this study was to determine if structural vibration testing can reveal the resonance frequencies that correspond to the mode shapes flexion–extension, lateroflexion and axial rotation of lumbar motion segments, and to establish whether resonance frequencies can discriminate specific structural alterations of the motion segment. Therefore, a shaker was used to vibrate the upper vertebra of 16 goat lumbar motion segments, while the response was obtained from accelerometers on the transverse and spinous processes and the anterior side of the upper vertebra. Measurements were performed in three conditions: intact, after dissection of the ligaments and after puncturing the annulus fibrosus. The results showed clear resonance peaks for flexion–extension, lateral bending and axial rotation for all segments. Dissection of the ligaments did not affect the resonance frequencies, but puncturing the annulus reduced the resonance frequency of axial rotation. These results indicate that vibration testing can be utilised to assess the modal parameters of lumbar motion segments, and might eventually be used to study the mechanical properties of spinal motion segments in vivo