Removal of mesh track on an upland blanket peatland leads to changes in vegetation composition and structure

Mesh tracks on peatlands are often granted permits on a temporary basis under the presumption that the tracks are either removed at the end of their permitted use or remain unused in situ. However, the fragility of peatland habitats and poor resilience of the specialist plant communities within them, mean that these linear disturbances may persist post-abandonment or post-removal. We removed sections of mesh track, abandoned five years earlier, from a blanket peatland using two different removal treatment methods (mown and unprepared) and studied a third treatment with sections left in place over a period of 19 months. On abandoned tracks, invasive species including Campylopus introflexus and Deschampsia flexulosa had established, while track removal led to extensive loss of Sphagnum species. Loss of surficial nanotopographic vegetation structures during track removal was extensive, and micro-erosion features were prevalent in both removal treatments. Abandoned sections of track performed comparably better across all metrics than removed sections. However, similarity between the vegetation assemblage of the abandoned track and the controls was <40% at the study outset, with NMDS (Non-metric Multidimensional Scaling) highlighting divergences. There was a mean species loss of 5 per quadrat for the removed sections. Bare peat was present in 52% of all track quadrats by the finish of the study. Our findings suggest that mesh tracks left in situ and track removal both present significant barriers to recovery and additional conservation interventions may be required after peatland tracks are abandoned.

Surface structure on abandoned upland blanket peatland tracks

Temporary permissions are often granted for track use on peatlands. However, even when peatland track designs attempt to minimise environmental impacts via use of mesh systems, such linear disturbances may have persistent impacts. We evaluated the surface peatland structure of five abandoned tracks (four with a mesh surface, one unsurfaced) with varying past usage frequencies, at an upland site in northern England. Simplification of the surface nanotopography was found on all tracks compared to surrounding control areas, with increased micro-erosion patterns in rutted areas, and invasive species on some treatments. The frequency of previous usage was not found to be a significant factor controlling nano-topographic loss. Edge effects and hillslope position were influential in places, but these effects were not consistent across treatments. Nano-topographic recovery was found to be inhibited when track usage commenced within a short time frame after track construction. Mesh tracks appear to create a spatial constraint leading to poor development of plants and a reduced ability to form characteristic structures which are integral to mire function.

Arable fields as potential reservoirs of biodiversity: Earthworm populations increase in new leys

Managing soil to support biodiversity is important to sustain the ecosystem services provided by soils upon which society depends. There is increasing evidence that functional diversity of soil biota is important for ecosystem services, and has been degraded by intensive agriculture. Importantly, the spatial distribution of reservoirs of soil biota in and surrounding arable fields is poorly understood. In a field experiment, grass-clover ley strips were introduced into four arable fields which had been under continuous intensive/conventional arable rotation for more than 10 years. Earthworm communities in arable fields and newly established grass-clover leys, as well as field boundary land uses (hedgerows and grassy field margins), were monitored over 2 years after arable-to-ley conversions. Within 2 years, earthworm abundance in new leys was 732 ± 244 earthworms m^-2, similar to that in field margin soils (619 ± 355 earthworms m^-2 yr^-1) and four times higher than in adjacent arable soil (185 ± 132 earthworms m^-2). Relative to the arable soils, earthworm abundance under the new leys showed changes in community composition, structure and functional group, which were particularly associated with an increase in anecic earthworms; thus new leys became more similar to grassy field margins. Earthworm abundance was similar in new leys that were either connected to biodiversity reservoirs i.e. field margins and hedgerows, or not (installed earthworm barriers). This suggests that, for earthworm communities in typical arable fields, biodiversity reservoirs in adjacent field margins and hedgerows may not be critical for earthworm populations to increase. We conclude that the increase in earthworm abundance in the new leys observed over 2 years was driven by recruitment from the existing residual population in arable soils. Therefore, arable soils are also potential reservoirs of biodiversity.

Effect of earthworms on soil physico-hydraulic and chemical properties, herbage production, and wheat growth on arable land converted to ley

Effects of earthworms on soil physico-hydraulic and chemical properties, herbage production and wheat growth in long-term arable soils following conversion to ley were investigated. Seven intact soil monoliths were collected from each of four arable fields. One monolith per field served as a control. The other six were defaunated by deep-freezing; three were left defaunated (DeF) and three (DeF+E) were repopulated with earthworms to mimic pasture field density and diversity. The monoliths were planted with a grass-clover ley and inserted into pre-established ley strips in their original fields for 12 months. Hydraulic conductivity measurements at -0.5 cm tension (K_0.5) were taken five times over the year. K_0.5 significantly increased in summer 2017 and spring 2018 and decreased in winter 2017-18. K_0.5 was significantly greater (47%) for DeF+E than DeF monoliths. By the end of the experiment, pores >1 mm diameter made a significantly greater contribution to water flow in DeF+E (98%) than DeF (95%) monoliths. After only a year of arable to ley conversion, soil bulk density significantly decreased (by 6%), and organic matter (OM) content increased (by 29%) in the DeF treatments relative to the arable soil. Earthworms improved soil quality further. Compared to DeF monoliths, DeF+E monoliths had significantly increased water-holding capacity (by 9%), plant-available water (by 21%), OM content (by 9%), grass-clover shoot dry biomass (by 58%), water-stable aggregates >250 μm (by 15%) and total N (by 3.5%). In a wheat bioassay following the field experiment, significantly more biomass (20%) was produced on DeF+E than DeF monolith soil, likely due to the changed soil physico-hydraulic properties. Our results show that earthworms play a significant role in improvements to soil quality and functions brought about by arable to ley conversion, and that augmenting depleted earthworm populations can help the restoration of soil qualities adversely impacted by intensive agriculture.

The impacts of prescribed moorland burning on water colour and dissolved organic carbon: a critical synthesis

Discolouration of natural surface waters due to the humic component of dissolved organic carbon (DOC) is a costly problem for water supply companies. This paper reviews what is known about the impacts of prescribed moorland vegetation burning on water colour. Relevant research has taken place at three scales: laboratory experiments on peat cores, plot scale sampling of soil waters and catchment scale sampling of stream waters. While laboratory studies suggest burning increases colour production, the evidence from catchment and plot studies is contradictory. Plot studies suggest colour production may decrease or remain unchanged following burning although there is evidence for some transient changes. Catchment studies suggest prescribed moorland burning causes stream water colour to increase, although in most cases the evidence is not clear cut since most studies could not clearly disentangle the effects of burning from those of vegetation cover. The differences in findings between plot and catchment studies may be explained by: i) the short-term nature of some studies which do not measure long-term response and recovery times to burning; ii) the lack of colour measurements from shallow soil depths which contribute more to streamflow than soil water from deeper in the peat; and iii) the possibility of hydrological interactions occurring between different experimental plots at some sites. Additionally, the increase in recent patch burning in some catchments that has been statistically attributed by some authors to increases in stream water colour cannot be reconciled with theoretical calculations. When dilution with waters derived from other parts of the catchment are taken into account, large values of colour have to be theoretically derived from those recently burnt areas that occupy a small proportion of the catchment area in order to balance the change in stream water colour observed in recent years. Therefore, much further process-based work is required to properly investigate whether prescribed vegetation burning is a direct driver of enhanced colour and DOC in upland streams, rivers and lakes.

The use of GIS and multi-criteria evaluation (MCE) to identify agricultural land management practices which cause surface water pollution in drinking water supply catchments

Diffuse pollution poses a threat to water quality and results in the need for treatment for potable water supplies which can prove costly. Within the Yorkshire region, UK, nitrates, pesticides and water colour present particular treatment problems. Catchment management techniques offer an alternative to 'end of pipe' solutions and allow resources to be targeted to the most polluting areas. This project has attempted to identify such areas using GIS based modelling approaches in catchments where water quality data were available. As no model exists to predict water colour a model was created using an MCE method which is capable of predicting colour concentrations at the catchment scale. CatchIS was used to predict pesticide and nitrate N concentrations and was found to be generally capable of reliably predicting nitrate N loads at the catchment scale. The pesticides results did not match the historic data possibly due to problems with the historic pesticide data and temporal and spatially variability in pesticide usage. The use of these models can be extended to predict water quality problems in catchments where water quality data are unavailable and highlight areas of concern.

Activation of human matrix metalloproteinase 2 by gingival crevicular fluid and Porphyromonas gingivalis

AIM

To assess the potential of gingival crevicular fluid (GCF) from adult periodontitis patients and Porphyromonas gingivalis proteases to activate matrix metalloproteinase 2 (MMP-2) in vitro.

MATERIAL AND METHODS

GCF samples were collected from each of 15 adult periodontitis patients, from a clinically healthy site, a deep (>6 mm) bleeding site, and a deep nonbleeding site. The GCF samples were examined for general proteolytic activity, gelatinolytic activity and ability to activate pro-MMP-2 by zymography. Ultrasonic extracts of a range of clinical isolates of P. gingivalis cells and purified arg- and lys-gingipains were also assessed for their ability to activate pro-MMP-2.

RESULTS

GCF from deep nonbleeding sites showed higher general proteolytic activity than samples from deep bleeding and healthy sites but this did not reach statistical significance. Pefabloc, a general serine protease inhibitor, inhibited the majority (92%) of the proteolytic activity. GCF samples contained neutrophil MMP-9 in its latent form in 93% of the samples, and in its activated form in 40% of the samples. In contrast, MMP-2 was present in only trace amounts in 9% of the samples. When latent MMP-2 was added to these GCF samples, it was converted to the activated form (59 kDa) in 68% of the samples. Lower molecular weight (55 and 45 kDa) activated forms also appeared in 53% of the samples, particularly those from deep sites. Activation to the 55 and 45 kDa forms was inhibited by MSAAPket (a neutrophil elastase inhibitor), whereas Pefabloc completely inhibited the activation of latent MMP-2. All ultrasonic extracts of P. gingivalis activated latent MMP-2 in a concentration- and time-dependent manner. Also, latent MMP-2 was activated by purified arg-gingipain but less efficiently by lys-gingipain.

CONCLUSION

These findings suggest that P. gingivalis arg-gingipain and neutrophil elastase present in GCF can activate latent MMP-2, which may contribute in vivo to local periodontal tissue destruction.

Temporomandibular disorder: efficacy of an oral habit reversal treatment program

Little attention has been directed at interventions that directly teach facial pain patients to detect, interrupt, and reverse the maladaptive oral habits and cognitions thought to be associated with muscle hyper-reactivity and pain. The present study tested a seven-session structured-group habit reversal treatment intervention for facial pain patients. Nine facial pain subjects participated in treatment groups and seven qualified subjects who did not participate in treatment served as a comparison group. Pre, post, and follow-up assessments included measures of pain and psychological functioning. Subjects in the treatment group improved on all measures of pain relative to those in the comparison group. These improvements were maintained or augmented at four month follow-up assessments suggesting that habit reversal training, particularly in a group format, may provide a cost-effective intervention for facial pain patients.

Buprenorphine reduces cerebral glucose metabolism in polydrug abusers

Buprenorphine is a mixed opioid agonist-antagonist, which acts as a partial mu agonist and a kappa antagonist. The present study evaluated the acute effects of buprenorphine on cerebral glucose metabolism (CMRglc) in six human substance abusers using a double-blind, placebo-controlled, counterbalanced, crossover design. Each subject participated in two positron emission tomographic (PET) studies, 1 week apart, following the injection of buprenorphine (1 mg, intramuscularly) and placebo. Buprenorphine significantly reduced CMRglc and the regional cerebral metabolic rate for glucose (rCMRglc) by up to 32% in all but three of 22 bilateral and in 4 midline regions (p < .05). No region showed an increase in rCMRglc. Buprenorphine also produced miosis, respiratory depression, and subjective ratings of euphoria and sedation in comparison to placebo (p < .05). These observations extend previous findings of reduced CMRglc following acute treatment with morphine and other nonopioid euphorigenic drugs.

Pressure-volume analysis as a method for quantifying simultaneous drug (amrinone) effects on arterial load and contractile state in vivo

Pressure-volume relation analysis was used to independently quantify changes in ventricular contractile performance and vascular loading in intact anesthetized dogs before and after a single bolus of intravenous amrinone. Ventricular systolic property changes were characterized by the end-systolic elastance (Ees = slope of the end-systolic pressure-volume relation) and arterial properties by the effective arterial elastance (Ea = end-systolic pressure/stroke volume ratio). Pressure-volume data were obtained by the conductance catheter technique with loading varied by transient inferior vena cava occlusion. Amrinone induced a 27% increase in ejection fraction at 10 min (from 44% to 56%) as a result of both a significant rise in contractility (mean Ees 4 +/- 2 to 6 +/- 3 mm Hg/ml, p less than 0.001) and simultaneous reduction in arterial loading (Ea reduction from 6 +/- 2 mm Hg/ml to 5 mm Hg/ml, p less than 0.001). Over the subsequent 30 min, Ea revealed a significant recovery toward baseline, whereas Ees was less altered. Mean percent changes (% delta) in both variables were linearly correlated: % delta Ea = -1.6 x % delta Ees + 3.1, r = 0.96, p less than 0.001. In addition to separating ventricular from vascular property changes, the pressure-volume coupling framework was used to predict net pump performance (ejection fraction). Model predictions showed good agreement with experimental data. Thus, pressure-volume relations can be used to separately quantitate simultaneous changes in ventricular and vascular loading properties in vivo produced by pharmacologic agents with complex actions. Use of this approach in drug testing in humans should simplify data interpretation regarding mechanisms of action in specific clinical settings.

Cocaine-induced reduction of glucose utilization in human brain. A study using positron emission tomography and [fluorine 18]-fluorodeoxyglucose

We examined the effects of cocaine hydrochloride (40 mg intravenously) on regional cerebral metabolic rates for glucose and on subjective self-reports of eight polydrug abusers in a double-blind, placebo-controlled, crossover study. The regional cerebral metabolic rate for glucose was measured by the [fluorine 18]-fluorodeoxyglucose method, using positron emission tomography. With eyes covered, subjects listened to a tape that presented white noise, "beep" prompts, and questions about subjective effects of cocaine or saline. Cocaine produced euphoria and reduced glucose utilization globally (mean reduction, 14%). Twenty-six of 29 brain regions (all neocortical areas, basal ganglia, portions of the hippocampal formation, thalamus, and midbrain) showed significant decrements (5% to 26%) in the regional cerebral metabolic rate for glucose. No significant effects of cocaine were observed in the pons, the cerebellar cortex, or the vermis. Right-greater-than-left hemispheric asymmetry of regional cerebral metabolic rates for glucose occurred in the lateral thalamus. The findings demonstrate that reduced cerebral metabolism is associated with cocaine-induced euphoria.