Planting hedgerows: Biomass carbon sequestration and contribution towards net-zero targets.

Agroforestry practices, such as hedgerow planting, are widely encouraged for climate change mitigation and there is an urgent need to assess their contribution to national 'net-zero' targets. This study examined the impact that planting hedgerows at different rates could make to UK net-zero goals over the next 40 years, with a focus on 2050. We analysed the carbon (C) content of native hedgerow species and determined hedge aboveground biomass (AGB) C stock via destructive sampling of hedges of known ages. AGB C stocks ranged from 8.34 Mg C ha-1 in the youngest hedges, to 40.42 Mg C ha-1 in old ones. Knowing the age of the hedgerows, we calculated their annual average AGB C sequestration rate, which was highest in young hedges (2.09 Mg C ha-1 yr-1), and lowest in 39 year old mature, regularly trimmed hedgerows (0.86 Mg C ha-1 yr-1). We present a time series of the annual AGB C sequestration rate change between hedge age categories, which increases from 2.09 Mg C ha-1 yr-1 in the first 6 years after planting, to 2.26 Mg C ha-1 yr-1 in the next 6 years, and then decreases to 0.43 Mg C ha-1 yr-1 between years 13 and 40. Our results indicate that, if encouraged widely, hedgerow planting can be a valuable tool for atmospheric CO2 capture and storage, contributing towards net-zero targets. However, current planting rates (1778.8 km yr-1) are too low to reach the net-zero goal set by the UK Climate Change Committee of increasing hedgerow length by 40 % by 2050. An increased planting rate of 7148.1 km yr-1 will achieve this goal by 2050, and, over 40 years, store 3.41 Tg CO2 in hedge AGB, or 10.13 Tg CO2 in hedge total biomass and in the soil, annually offsetting 1.5 %-4.5 % of UK annual agricultural CO2 emissions.

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.

Soil carbon sequestration potential of planting hedgerows in agricultural landscapes.

Realising the carbon (C) sequestration capacity of agricultural soils is needed to reach Paris Climate Agreement goals; thus, quantifying hedgerow planting potential to offset anthropogenic CO2 emissions is crucial for accurate climate mitigation modelling. Although being a widespread habitat in England and throughout Europe, the potential of hedgerows to contribute to net-zero targets is unclear. This is the first study to quantify the soil organic carbon (SOC) sequestration rate associated with planting hedgerows. We derived SOC stocks beneath hedgerows based on two estimation methods to assess differences from adjacent intensively managed grassland fields and how these may be affected by sampling depth and hedgerow age, as well as the SOC estimation method used. Twenty-six hedgerows on five dairy farms in Cumbria, England, were classified based on the time since their planting. We measured SOC stocks in 10 cm depth intervals in the top 50 cm of soil beneath hedgerows and in adjacent grassland fields. SOC beneath hedgerows was on average 31.3% higher than in the fields, 3.3% for 2-4 year old hedgerows, 14.4% for 10 year old, 45.2% for 37 year old, and 57.2% for older ones. We show that SOC sequestration rate beneath 37 year old hedgerows was 1.48 Mg C ha-1 yr-1 in the top 50 cm of soil. If England reaches its goal of a 40% increase in hedgerow length, 6.3 Tg CO2 will be stored in the soil over 40 years, annually offsetting 4.7%-6.4% of present-day agricultural CO2 emissions. However, the current rate of planting funded by agri-environment schemes, which today reaches only 0.02% of emissions, is too slow. Private-sector payments for ecosystem services initiatives (e.g., 'Milk Plan') show much higher rates of planting and are needed alongside agri-environment schemes to ensure hedgerow planting contributes to net-zero targets.

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 (K0.5) were taken five times over the year. K0.5 significantly increased in summer 2017 and spring 2018 and decreased in winter 2017-18. K0.5 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.

Improved automation of dissolved organic carbon sampling for organic-rich surface waters.

In-situ UV-Vis spectrophotometers offer the potential for improved estimates of dissolved organic carbon (DOC) fluxes for organic-rich systems such as peatlands because they are able to sample and log DOC proxies automatically through time at low cost. In turn, this could enable improved total carbon budget estimates for peatlands. The ability of such instruments to accurately measure DOC depends on a number of factors, not least of which is how absorbance measurements relate to DOC and the environmental conditions. Here we test the ability of a S::can Spectro::lyser™ for measuring DOC in peatland streams with routinely high DOC concentrations. Through analysis of the spectral response data collected by the instrument we have been able to accurately measure DOC up to 66 mg L(-1), which is more than double the original upper calibration limit for this particular instrument. A linear regression modelling approach resulted in an accuracy >95%. The greatest accuracy was achieved when absorbance values for several different wavelengths were used at the same time in the model. However, an accuracy >90% was achieved using absorbance values for a single wavelength to predict DOC concentration. Our calculations indicated that, for organic-rich systems, in-situ measurement with a scanning spectrophotometer can improve fluvial DOC flux estimates by 6 to 8% compared with traditional sampling methods. Thus, our techniques pave the way for improved long-term carbon budget calculations from organic-rich systems such as peatlands.

A nonverbal learning disability in a case of central hypoventilation syndrome without a PHOX2B gene mutation.

This study examines the neuropsychological profile of a boy with congenital central hypoventilation syndrome (CCHS) without a paired-like homeobox gene (PHOX2B) mutation. CCHS is a rare disorder of autonomic nervous system development characterized by an impaired ventilatory response to hypercarbia and hypoxemia. Mild intellectual deficits are common but a specific cognitive profile is not established in CCHS. We describe a nonverbal learning disorder as a CCHS endophenotype and recommend that detailed neuropsychological testing be performed on all individuals with CCHS. Defining the psycho-educational needs in CCHS may avert compounding the emotional and medical stresses of this already debilitating disorder.

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.

Reliability, validity, and preliminary normative data for the Children's Aggression Scale-Teacher Version.

OBJECTIVE: To provide preliminary psychometric data on the Children's Aggression Scale-Teacher Version (CAS-T), which was designed to assess severity and frequency of aggressive, as distinct from nonaggressive, disruptive behaviors. METHOD: The CAS-T has 23 items representing five domains: Verbal aggression, Aggression against objects and animals, Provoked physical aggression, Unprovoked physical aggression, and Use of weapons. The CAS-T was completed for 273 nonreferred boys and 67 clinically referred children (60 boys; 7 girls). Coefficient alpha was assessed separately in clinical and nonreferred groups. Validity was evaluated by comparing CAS-T scores of children with different disruptive behavior disorder diagnoses and by examining the relationship of CAS-T scores to other parent and teacher ratings. RESULTS: The scale as a whole had excellent reliability as measured by coefficient alpha. Children with conduct disorder were rated significantly higher than those with oppositional defiant disorder, attention-deficit/hyperactivity disorder, and no disruptive behavior disorder diagnosis. Further, patterns of correlations with other rating scales provide strong support for the convergent and discriminant validity of the CAS-T. CONCLUSIONS: The CAS-T may fill a gap in that it distinguishes among various types and severity of aggression, as distinct from oppositional-defiant behaviors.