Applying MERLIN for modelling nitrate leaching in a nitrogen saturated Douglas fir forest in the Netherlands after decreased atmospheric nitrogen input.

International audienceThe MERLIN model was applied on the results of a field-scale manipulation experiment with decreased nitrogen (N) deposition in an N saturated forest ecosystem in the Netherlands. The aim was to investigate the mechanisms that could explain the observed rapid response of nitrate as a result of the decreased N input. Calibrating the model to pre-treatment data revealed that, despite the high atmospheric N input, the trees relied on N mineralised from refractory organic matter (ROM) for their growth. MERLIN could simulate only the fast response of nitrate leaching after decreased input if this ROM mineralisation rate was decreased strongly at the time of the manipulation experiment

Environment and Rural Affairs Monitoring & Modelling Programme - ERAMMP Year 1 Report 21: GMEP outstanding analysis part 2 - Revisiting trends in topsoil carbon from CS2007 to GMEP 2013-2016

New analysis was carried out to explore the reported loss of topsoil-C between 2007 and 2016 in the ‘Habitat’ category in the final GMEP report. This ‘Habitat’ category is defined as all habitats except woodlands, arable and improved grassland. The GMEP survey squares were selected using Countryside Survey protocols stratified according to Land Classes. The final GMEP survey sample from 2012-2016 consists of 7% previously surveyed Countryside Survey squares. Further analysis was needed to explore, and account for, unintended shifts in environmental variables which could have contributed to the reported topsoil carbon decline. The results indicate: 1. The reported change in the ‘Habitat’ category is driven by trends in upland habitats (median elevation of 400m). 2. In upland habitats, soil carbon is positively associated with dwarf shrub cover (particularly ericoid e.g. heather cover), Sphagnum, presence of peat, elevation and moisture conditions. 3. The coverage of dwarf shrubs was lower in GMEP than in Countryside Survey 2007, mostly due to lower cover of ericoids i.e. heather. This is consistent with decreasing soil carbon in upland habitats. Other variables (i.e. potential drivers) did not differ between surveys, or direction of change was inconsistent with reported C trends. 4. Re-analysis of Countryside Survey data (1978-2007) provides evidence that shifts over time from dwarf shrub to grass-dominated habitats are associated with a decline in topsoil carbon. 5. Overall, this suggest a potential role of ongoing vegetation change in upland habitats (i.e. conversion of dwarf shrub to grass-dominated) contributing to topsoil carbon loss. Further work is needed to: • Confirm recent vegetation change in upland habitats using independent data e.g. satellite data; • Explore relationships between specific plant species and topsoil carbon in Countryside Survey where we have a high number of true repeat samples; This work highlights the importance of the findings of the next ERAMMP survey, which will be more powerful than the combined CS-GMEP approach reported here

Environment and Rural Affairs Monitoring & Modelling Programme - ERAMMP Year 1 Report 15: Responsive Monitoring Part 1 - Selection of ERAMMP field survey squares

A reduction in the number of GMEP squares to be revisited in the ERAMMP field survey is required to meet budgetary constraints whilst ensuring the survey will deliver the most robust evidence base which is responsive to such issues as the actual uptake of different Glastir interventions by contract-holders/land-managers and the capture of those within the baseline GMEP survey. An approach was needed which would maximise outputs matched to policy priorities for assessing national trends, provide evidence for the outcomes of Glastir interventions and optimise where changes were most likely to be detected. The target is to reduce survey squares from 300 to 240 1km squares

Environment and Rural Affairs Monitoring & Modelling Programme - ERAMMP Report-43: Analysis of National Monitoring Data to Inform Future Land Management Schemes in Wales.

The purpose of this work was to provide more in-depth analysis of the field survey data collected under the GMEP project between 2013 – 2016 to inform both future analysis of Glastir outcomes and the design of the Sustainable Farm Scheme in Wales

Environment and Rural Affairs Monitoring & Modelling Programme ERAMMP Report-28B: Welsh Mountain, Moor and Heath (MMH) Condition Account

1. Natural Capital Accounts for woodland, farmland and freshwater broad habitats were produced by ERAMMP in collaboration with the Office of National Statistics in 2017. These accounts estimated the combined partial asset value for these habitats to be £30.5 billion for 2014. A new monetary account has now been created for Mountain, Moor and Heath (MMH) habitat. This account estimates the MMH asset value to be £3 billion for 2018. 2. It is noted in all the reports produced that Office for National Statistics produced Natural Capital accounts remain experimental and future publications will be subject to methodological improvements. Also, it should be noted that all accounts only represent partial or a minimum valuation as methods are not available for all services. 3. This partial asset value for MMH is a relatively small asset figure – but it underlines how cheaply the products of the environment are rather than how important they are. The price is an important signal of levels of trade. If we are to decouple economic production and growth from environmental impact then the raw price ought to remain low with most value added upstream in the supply chain. If we were to look at the final consumer value of products from Welsh upland agriculture, it would be significantly higher. 4. For all of these accounts, the condition of the various broad habitats are not included explicitly as these are not typically represented in the reporting of many natural capital accounts by the Office of National Statistics. This means the rich set of condition data from the GMEP and ERAMMP National Field Survey and many other sources have not been exploited. These condition data are particularly important for assessing the underpinning resilience of ecosystems to sudden shocks. In addition, as standalone indicators these condition metrics help us to track the outcomes of policy (and other) interventions in improving the health of our ecosystems. 5. To test out the value of assessing condition data, this report presents a condition account for the Mountain, Moor and Heath (MMH) habitat. This is an important habitat for many cultural, provisioning and regulating services in Wales. The methodology used was informed by, but deviated to some extent, from the internationally accepted standard to increase the relevance for Welsh policy needs. 6. A first step was to agree which data would provide efficient, robust and repeatable information representative of the habitat condition. A participatory approach was taken to achieve this involving a range of actors to select the indicators which had greatest consensus as being appropriate and understandable to a broad audience. It was agreed, the relevance of these indicators to the delivery of a range of services and benefits should be the priority. A decision relating to a reference point was also needed i.e. how does current condition compare to either a theoretical ‘intact’ ecosystem, a reference year, or a policy target? A pragmatic approach was taken and the final selected reference point was based on the year(s) from which most historic data is available. 7. In summary, the trends reported for the final selected list of indicators in MMH since the 1990s (2010s only for some indicators) reported are: a) Water quality – a general improved in quality has been observed since the 1990s b) Soil quality - no change has been observed in 2 selected soil indicators since the 1990s c) Moorland Bird index – a decline has been observed which has stabilised since 2009 d) Habitat Connectivity - status but no trend data is available e) Protected sites – most are in unfavourable condition with little improvement observed over time f) Wildfires – increases have been observed since the 2010s g) Access – no trend data are available h) Visitor satisfaction – a high satisfaction rating is reported but no trend data is available 8. The monetary accounts for MMH suggest the value has been relatively stable over the time period for which we have enough data (2009-2018). This would seem to concur with these condition accounts where overall there is no ongoing decline but there is also only limited improvement observed. 9. In conclusion, there is a complex mix of drivers and policies interacting on the selected indicators. This is further confounded by different sensitivity of indicators to these drivers and variability in historic data sources. However there are some clear policy messages with respect to policy outcomes: a) major policy success (e.g. MMH water quality recovering from acidification) b) partial policy success halting decline (e.g. Moorland Bird Index; stability in soil indicators) c) outstanding policy needs (e.g. no improvement in status of protected sites; increase in wildfire frequency). 10. Availability of new sources of data will allow improvement going forward in any future condition accounts. For example not all sources of GMEP/ERAMMP data were explored due to lack of availability of ONS staff resources due to their heavy engagement in the covid response. One recommendation is to increase engagement with the ONS team to ensure more effective use of Welsh data streams going forward even in the creation of UK accounts. A priority going forward is to develop methods to better embed these condition indicators in the monetary accounts

Multiple soil map comparison highlights challenges for predicting topsoil organic carbon concentration at national scale

Soil organic carbon (SOC) concentration is the fundamental indicator of soil health, underpinning food production and climate change mitigation. SOC storage is highly sensitive to several dynamic environmental drivers, with approximately one third of soils degraded and losing carbon worldwide. Digital soil mapping illuminates where hotspots of SOC storage occur and where losses to the atmosphere are most likely. Yet, attempts to map SOC often disagree. Here we compare national scale SOC concentration map products to reveal agreement of data in mineral soils, with progressively poorer agreement in organo-mineral and organic soils. Divergences in map predictions from each other and survey data widen in the high SOC content land types we stratified. Given the disparities are highest in carbon rich soils, efforts are required to reduce these uncertainties to increase confidence in mapping SOC storage and predicting where change may be important at national to global scales. Our map comparison results could be used to identify SOC risk where concentrations are high and should be conserved, and where uncertainty is high and further monitoring should be targeted. Reducing inter-map uncertainty will rely on addressing statistical limitations and including covariates that capture convergence of physical factors that produce high SOC contents

Environment and Rural Affairs Monitoring & Modelling Programme – ERAMMP Report-26: ‘Quick Start’ Agricultural Small Sectors Modelling.

The potential impact of Brexit on the farming sector and wider environment is just one of the many challenges facing the Welsh Government. There are a range of decision and modelling tools which can be used to explore potential outcomes and the areas at risk where the environmental regulatory floor needs to be enhanced or social transition programmes put in place. To meet this challenge in Wales, a partnership between the Welsh Government, their stakeholders and a consortium of research organisations led by the UK Centre for Ecology and Hydrology (UKCEH) was formed. This partnership, called ERAMMP, (https://erammp.wales/en) combined expert knowledge and a range of decision and modelling tools to examine potential changes in agricultural land use that might result from Brexit, and to explore potential benefits of new land management options