Jonathan P. Evans

Sampling spatial and temporal variation in soil nitrogen availability

Abstract There are few studies in natural ecosystems on how spatial maps of soil attributes change within a growing season. In part, this is due to methodological difficulties associated with sampling the same spatial locations repeatedly over time. We describe the use of ion exchange membrane spikes, a relatively nondestructive way to measure how soil resources at a given point in space fluctuate over time. We used this method to examine spatial patterns of soil ammonium (NH+4) and nitrate (NO−3) availability in a mid-successional coastal dune for four periods of time during the growing season. For a single point in time, we also measured soil NH+4 and NO−3 concentrations from soil cores collected from the mid-successional dune and from an early and a late successional dune. Soil nitrogen concentrations were low and highly variable in dunes of all ages. Mean NH+4 and NO−3 concentrations increased with the age of the dune, whereas coefficients of variation for NH+4 and NO−3 concentrations decreased with the age of the dune. Soil NO−3 concentration showed strong spatial structure, but soil NH+4 concentration was not spatially structured. Plant-available NH+4 and NO−3 showed relatively little spatial structure: only NO−3 availability in the second sampling period had significant patch structure. Spatial maps of NH+4 and NO−3 availability changed greatly over time, and there were few significant correlations among soil nitrogen availability at different points in time. NO−3 availability in the second sampling period was highly correlated (r = 0.90) with the initial soil NO−3 concentrations, providing some evidence that patches of plant-available NO−3 may reappear at the same spatial locations at irregular points in time.

Frozen shoulder: A systematic review of therapeutic options

Frozen shoulder is a common disease which causes significant morbidity. Despite over a hundred years of treating this condition the definition, diagnosis, pathology and most efficacious treatments are still largely unclear. This systematic review of current treatments for frozen shoulder reviews the evidence base behind physiotherapy, both oral and intra articular steroid, hydrodilatation, manipulation under anaesthesia and arthroscopic capsular release. Key areas in which future research could be directed are identified, in particular with regard to the increasing role of arthroscopic capsular release as a treatment.

Mapping Land-Use Change and Monitoring the Impacts of Hardwood- to-Pine Conversion on the Southern Cumberland Plateau in Tennessee

Abstract Over the past two decades, forests in the southeastern United States have undergone dramatic changes as the result of urban sprawl and conversion to intensively managed pine plantations. The Cumberland Plateau, an important ecoregion in the southeastern United States, contains some of the largest remaining tracts of privately owned, native hardwood forest in North America. These ecologically important forests have been undergoing increasingly rapid rates of hardwood-to-pine conversion, much of which has gone undetected by large-scale statewide inventories. Forest conversion in Tennessees southern Cumberland Plateau provides a case study highlighting the need for interdisciplinary and spatially explicit assessments of the impact and drivers of land-use change at smaller scales. Aerial and satellite imagery were used to create computer-generated maps of land use and forest cover for a 243 000 ha study area within a seven-county region of the southern Cumberland Plateau in Tennessee to track and do...

Depauperate avifauna in plantations compared to forests and exurban areas.

Native forests are shrinking worldwide, causing a loss of biological diversity. Our ability to prioritize forest conservation actions is hampered by a lack of information about the relative impacts of different types of forest loss on biodiversity. In particular, we lack rigorous comparisons of the effects of clearing forests for tree plantations and for human settlements, two leading causes of deforestation worldwide. We compared avian diversity in forests, plantations and exurban areas on the Cumberland Plateau, USA, an area of global importance for biodiversity. By combining field surveys with digital habitat databases, and then analyzing diversity at multiple scales, we found that plantations had lower diversity and fewer conservation priority species than did other habitats. Exurban areas had higher diversity than did native forests, but native forests outscored exurban areas for some measures of conservation priority. Overall therefore, pine plantations had impoverished avian communities relative to both native forests and to exurban areas. Thus, reports on the status of forests give misleading signals about biological diversity when they include plantations in their estimates of forest cover but exclude forested areas in which humans live. Likewise, forest conservation programs should downgrade incentives for plantations and should include settled areas within their purview.

Ten years of forest change in two adjacent communities on the southern Cumberland Plateau, U.S.A

Abstract Forests of the Cumberland Plateau physiographic province have undergone significant change over the past century due to anthropogenic disturbances, and the magnitude and direction of this change will have important consequences for forest management and biodiversity conservation. Cove and upland forest communities on the Cumberland Plateau are in close proximity to one another, but have maintained distinct composition due to soil differences. Several anthropogenic influences common to other southern Appalachian forest communities, including fire suppression, predator removal, and introduction of pathogens, continue to drive change in these forests but remain relatively undocumented. In this 10-year study of these two major forest types, those disturbances were expected to homogenize cove and upland forests, with compositions increasingly dominated by generalist species, similar to trends elsewhere. Composition and structure were considerably altered in both communities over the course of this study, but non-metric multidimensional scaling showed that the cove and uplands remained distinct. Both communities were experiencing a steady replacement of Quercus species by Acer species, but A. saccharum and A. rubrum dominance were limited to the cove and uplands respectively. A. saccharum expansion in the coves is in contrast to trends reported in other studies of Appalachian forests. Replacement of Quercus species by Acer species was more advanced in the high-productivity cove forest; however, the trajectory of change was more consistent among upland forest plots. Documenting long-term status and trends in these forested communities will be critical for managing disturbance regimes and predicting consequences for regional biodiversity.

Twelve years of repeated wild hog activity promotes population maintenance of an invasive clonal plant in a coastal dune ecosystem

Abstract Invasive animals can facilitate the success of invasive plant populations through disturbance. We examined the relationship between the repeated foraging disturbance of an invasive animal and the population maintenance of an invasive plant in a coastal dune ecosystem. We hypothesized that feral wild hog (Sus scrofa) populations repeatedly utilized tubers of the clonal perennial, yellow nutsedge (Cyperus esculentus) as a food source and evaluated whether hog activity promoted the long‐term maintenance of yellow nutsedge populations on St. Catherines Island, Georgia, United States. Using generalized linear mixed models, we tested the effect of wild hog disturbance on permanent sites for yellow nutsedge culm density, tuber density, and percent cover of native plant species over a 12‐year period. We found that disturbance plots had a higher number of culms and tubers and a lower percentage of native live plant cover than undisturbed control plots. Wild hogs redisturbed the disturbed plots approximately every 5 years. Our research provides demographic evidence that repeated foraging disturbances by an invasive animal promote the long‐term population maintenance of an invasive clonal plant. Opportunistic facultative interactions such as we demonstrate in this study are likely to become more commonplace as greater numbers of introduced species are integrated into ecological communities around the world.

The Vascular Flora of the University of the South, Sewanee, Tennessee

ABSTRACT  Sewanee: The University of the South, located in Franklin County, Tennessee, is a 5,263 ha site that encompasses a variety of plateau and cove habitats on the southern Cumberland Plateau in southeastern Tennessee. The vascular flora of the University of the South was documented from 1948–2015 and comprises 1,118 species and lesser taxa in 553 genera and 150 families. We documented 229 exotic taxa, 20.5% of the flora. This flora contains six state records, 74 Franklin County records, and two potential new species. Eighteen taxa are listed as protected either at the state or federal level, including the federally listed endangered Clematis morefieldii and state listed endangered Diamorpha smallii, Silphium brachiatum, and Symphyotrichum pratense. When compared to the five other published floras for the southern Cumberland Plateau in Tennessee, the University of the South flora is the most diverse, capturing 69% of the total taxa at the species level for the region. The high diversity of plant species in the University of the South flora reflects the broad range of habitats that can be found within the campus and contiguous natural areas. This flora demonstrates that herbaria at small liberal arts colleges can play an important role in the documentation and promotion of plant biodiversity within their region.

Case series of pectoralis major rupture requiring operative intervention sustained on the Royal Marines ‘Tarzan’ assault course

We present (with intra-operative imaging) four patients who sustained pectoralis major (PM) ruptures on the same piece of equipment of the ‘Tarzan’ assault course at the Commando Training Centre, Royal Marines (CTCRM). Recruits jump at running pace, carrying 21 lbs of equipment and a weapon (8 lbs) across a 6-feet gap onto a vertical cargo-net. The recruits punch horizontally through the net, before adducting their arm to catch themselves, and all weight, on their axilla. All patients presented with immediate pain and reduced function. Two had ruptures demonstrated on magnetic resonance imaging, one on an ultrasound scan and one via clinical examination. All four patients were found, at operation, to have sustained type IIIE injuries. All patients underwent PM repair using a unicortical button fixation and had an uneventful immediate postoperative course. Patient 1 left Royal Marines training after the injury (out of choice; not because of failure to rehabilitate). All other patients are under active rehabilitation, hoping to return to training. Review of 10 years of records at CTCRM reveal no documented PM rupture prior to our first case in October 2013. There has been no change to the obstacle or technique used and all patients deny the use of steroids.

Does the triceps-on approach affect alignment in total elbow arthroplasty? A cadaveric study:

Background The triceps-on approach for total elbow arthroplasty has gained popularity due to the theoretical benefit of preserving the extensor mechanism. However, there is concern that the exposure may be reduced in comparison to a triceps-off approach and may affect the implant alignment achieved. Method Total elbow arthroplasties were implanted in 18 randomised, paired cadaveric elbows using the triceps-on or triceps-off approach. The bones were dissected out and the position of the implants measured relative to anatomical landmarks. The flexion/extension and varus/valgus angles, and the distance of centre of rotation from the anatomic centre of rotation in the sagittal plane for both components were obtained as well as the humeral component rotation relative to the transepicondylar axis. Results All humeral components were positioned in external rotation and all ulna components were placed in flexion. Seven components were positioned greater than 5° away from the ideal in one measurement, with no significant difference between the two approach groups. Discussion This unique study showed no significant difference in the alignment of the implants between the two approaches. These results support the theory that the triceps-on approach does not result in larger alignment errors in component positioning when performing total elbow arthroplasty.