A meta-analysis on the impact of different matrix structures on species movement rates

Many biodiversity conservation strategies aim to increase species movement by changing the landscape between suitable areas of habitat. We applied systematic review and meta-analytical methods to robustly assess evidence on the impact of matrix structure on movement rates, with the hypothesis that movement will be greater through matrix of a more similar structure (vegetation height and cover) to the home habitat. Twenty studies of movement through two or more different matrix types provided 107 effect sizes, expressing the difference between the relative movement rates in different matrix types. The studies were all on animals, including relatively mobile taxa such as birds and butterflies but also rodents and amphibians. We were able to detect that on average, movement was greater through matrix of a more similar structure to the species?? habitat despite the variation in studies in terms of matrix types, species and methods. The effect size was larger when there was a greater difference in the structure of the two matrix types being compared (e.g. comparing grassland to forest rather than short grass to long grass). However, there was a high degree of covariation between matrix contrast and studies and other significant subgroupings such as taxonomic group and matrix openness. The biological significance of the increase in movement is not clear; however, ecological theory predicts dispersing individuals are important for population dynamics. Changes to the structure of landscapes intended to improve permeability to movement are supported by the findings of this study, particularly for relatively mobile species. However, research over longer timescales, greater distances and range of taxonomic groups is necessary.     

Impacts of grazing on lowland heathland in north-west Europe

Lowland heathland habitats are recognized to be of high conservation value throughout north-west Europe. Current management approaches focus on arresting natural succession to woodland, and include the use of vegetation cutting, burning and grazing by livestock. However, the introduction of grazing has proved controversial, highlighting the need for evidence regarding its effectiveness. A systematic review of the scientific literature was therefore performed, which identified 13 studies with appropriate comparators (such as untreated controls). Meta-analysis of these data indicated that grazing can result in an increase in the ratio of grassland to ericoid shrub cover, but insufficient experimental evidence was available to assess the effectiveness of any other intervention, indicating a lack of replicated studies with controls. Two forms of expert knowledge were also compiled, based on information in the scientific literature excluded from the meta-analysis, and questionnaire responses of heathland managers. While these two evidence sources were generally in close correspondence, beliefs of heathland managers contradicted the scientific literature with respect to the impact of grazing on the ratio of grassland to ericoid shrubs. Incorporating a range of evidence sources in systematic reviews can therefore provide insights into contradictions in the evidence base. While a large majority of practitioners (94%) believe that grazing is an effective management option for lowland heath, evidence for a number of negative impacts on habitat attributes was recorded, highlighting the need for improved monitoring and experimental analysis of the effectiveness of management interventions.     

Effects of cluster light exposure on 3-isobutyl-2-methoxypyrazine accumulation and degradation patterns in red wine grapes ( Vitis vinifera L. Cv. Cabernet Franc)

The effects of light exposure on 3-isobutyl-2-methoxypyrazine (IBMP) accumulation and degradation in Vitis vinifera L. cv. Cabernet Franc berries were assessed by comparison of shaded and exposed clusters within the same vine throughout a growing season. Twenty-seven vines were shoot-thinned to create regions of high and low cluster-light exposure within each vine. Samples were collected at 10 time points starting from 5 to 130 days postbloom. The experimental design allowed for intravine comparison of IBMP levels between treatments at each time. Vine-to-vine variability of IBMP and the correlation of IBMP to malic acid were also evaluated. Cluster exposure reduced accumulation of IBMP at all preveraison time points by 21-44%, but did not increase postveraison degradation. Significant vine-to-vine variability in IBMP content was observed, with the highest level of IBMP in shaded berries in the most vigorous block of vines. Although IBMP concentration by weight decreased significantly due to dilution just prior to color change (veraison), no significant IBMP degradation per berry occurred until after color change (day 70 postbloom). By contrast, malic acid degradation began prior to color change, and malic acid concentrations were not affected by cluster exposure preveraison, but were affected postveraison. A survey of 13 sites in New York state (Seneca Lake) showed that IBMP concentrations at 2 weeks preveraison were highly correlated (R(2) = 0.936, p < 0.0001) to levels at harvest, whereas classic grape maturity indices at harvest were uncorrelated with IBMP at harvest. In summary, light exposure conditions critically influence IBMP accumulation but not IBMP degradation.     

Pneumonia after intracranial surgery in dogs

OBJECTIVE: To determine factors associated with the occurrence of pneumonia after intracranial surgery in dogs. STUDY DESIGN: Retrospective cohort study. Animals-Forty-nine client-owned dogs. METHODS: The medical records of 49 dogs with space-occupying intracranial disease that underwent craniotomy were reviewed. Development of pneumonia after surgery was considered highly likely in 12 dogs (affected dogs) based on clinical signs, including acute dyspnea or coughing in association with typical radiographic findings or abnormal transtracheal wash results. Pneumonia was confirmed in 6 dogs based on necropsy findings. Affected dogs were compared with 37 dogs that did not develop pneumonia (unaffected dogs) subsequent to intracranial surgery. Based on the medical records of affected dogs, determinations were made regarding time between development of pneumonia and surgery, surgical procedure, intracranial lesion type, and intracranial lesion location. Risk factors examined for both affected and unaffected dogs included level of consciousness, body position during the postoperative recovery period, duration of anesthesia, occurrence of vomiting or regurgitation, presence of seizures, cranial nerve deficiencies, and the presence of megaesophagus before and after surgery. We also compared the feeding protocol after surgery for each group. RESULTS: Pneumonia typically occurred within the first week after surgery (median, 6.5 days); however, this was variable (range, 1-96 days). Of the factors that were present within 24 hours before the clinical signs of pneumonia, vomiting or regurgitation and megaesophagus were found to be significant risk factors. Dogs that vomited or regurgitated were 2.71 times more likely to develop pneumonia than dogs that did not. Vomiting or regurgitation occurred in 63% of the dogs that developed pneumonia in this cohort. Dogs with megaesophagus were 9.25 times more likely to develop pneumonia than dogs without megaesophagus. Seven dogs with pneumonia died. Five of these 7 dogs appeared to have died as a direct sequel to pneumonia. CONCLUSION: Dogs undergoing craniectomies for space-occupying intracranial disease may be at higher risk for development of pneumonia due to several factors, including vomiting, regurgitation, and megaesophagus.     

SPATIAL ACCURACY OF FRACTIONATED IMRT DELIVERY STUDIES IN CANINE PARASPINAL IRRADIATION

Intensity modulated radiation therapy (IMRT) theoretically allows detailed tailoring of the dose distribution in tissue. The goal of this study was to determine if a method of dynamic IMRT could be used to deliver a high dose of radiation to a concave shaped target around the cervical spinal cord. Fifteen young adult dogs from our laboratory population were randomly divided into two groups. A radiation dose of 84 Gy in 4 Gy fractions was delivered with a conventional 4 field technique for Group A dogs, and with dynamic IMRT for Group B dogs to a "C-shaped" target close to the cervical spinal cord. Neurologic status, magnetic resonance imaging results and histopathologic changes were compared among dogs in the two groups. Group A dogs developed myelomalacia with a latency period of 65 +/- 9 days. Group B dogs did not have any histologic changes to the cervical spinal cord when euthanasia was performed 12 months after irradiation. The results demonstrate that this IMRT technique can be safely and precisely delivered to a patient in a clinical situation.     

A whole-plant chamber system for parallel gas exchange measurements of Arabidopsis and other herbaceous species

Background

Photosynthetic assimilation of carbon is a defining feature of the plant kingdom. The fixation of large amounts of carbon dioxide supports the synthesis of carbohydrates, which make up the bulk of plant biomass. Exact measurements of carbon assimilation rates are therefore crucial due to their impact on the plants metabolism, growth and reproductive success. Commercially available single-leaf cuvettes allow the detailed analysis of many photosynthetic parameters, including gas exchange, of a selected leaf area. However, these cuvettes can be difficult to use with small herbaceous plants such as Arabidopsis thaliana or plants having delicate or textured leaves. Furthermore, data from single leaves can be difficult to scale-up for a plant shoot with a complex architecture and tissues in different physiological states. Therefore, we constructed a versatile system—EGES-1—to simultaneously measure gas exchange in the whole shoots of multiple individual plants. Our system was designed to be able record data continuously over several days.

Results

The EGES-1 system yielded comparable measurements for eight plants for up to 6 days in stable, physiologically realistic conditions. The chambers seals have negligible permeability to carbon dioxide and the system is designed so as to detect any bulk-flow air leaks. We show that the system can be used to monitor plant responses to changing environmental conditions, such as changes in illumination or stress treatments, and to compare plants with phenotypically severe mutations. By incorporating interchangeable lids, the system could be used to measure photosynthetic gas exchange in several genera such as Arabidopsis, Nicotiana, Pisum, Lotus and Mesembryanthemum.

Conclusion

EGES-1 can be introduced into a variety of growth facilities and measure gas exchange in the shoots diverse plant species grown in different growth media. It is ideal for comparing photosynthetic carbon assimilation of wild-type and mutant plants and/or plants undergoing selected experimental treatments. The system can deliver valuable data for whole-plant growth studies and help understanding mutant phenotypes. Overall, the EGES-1 is complementary to the readily-available single leaf systems that focus more on the photosynthetic process in within the leaf lamina.