Annex B – Follow–on to the Initial Evaluation of ES MA01041.
SPECIFICATION
PART A: Estimating impacts of ELS on diffuse pollution of surface waters by nitrates and phosphates.
Background
An evaluation of Environmental Stewardship had recently been carried out by CSL. As part of this project, a modelling process was developed which attempted to estimate the impact of ELS on a range of indicators. The process adopted depended on expert scores for the effectiveness of each option, and estimates of the optimal area required to achieve targets. However, the process was not as successful as intended for resource protection because the impact of many options on water quality depends on their location. This proposal therefore aims to develop an alternative method of estimating the impact of ELS uptake on water quality.
Originally, targets were set in terms of pollutant concentrations in surface waters, as these are the measures to be used in implementing the Water Framework Directive. However, these concentrations are not only a result of diffuse pollution from agriculture, but also point source pollution from agriculture and other sources (e.g. sewage works). Furthermore, the concentration in water depends on a range of factors including the size of the watercourse, its rate of flow etc. Determining the impact of measures to reduce losses from agriculture on nutrient pollutant concentrations in water is therefore complex; for the present purpose it is more appropriate to consider the effect of ELS options on losses from agricultural land only. It is proposed that phosphate and nitrate losses from agricultural land are adopted as the indicators to be studied, because they are likely to be affected by a range of options, and the mechanisms underlying their movement to watercourses differ. In the case of phosphate, pollution is linked to soil erosion, and there is a Defra target for reduction of losses (48%), as quoted by Anthony (2006), which can be used as a benchmark.
Objectives
1. To estimate the impact of ELS options on diffuse nutrient losses from agricultural land;
2. (a) To estimate the amount of individual options required to maximise impact of the ELS on diffuse nitrate and phosphate losses, and
(b) To determine the optimal locations of options, where appropriate;
3. To compare estimated impacts on nitrate and phosphate losses based on current uptake data with potential impacts based on optimal uptake.
Methods
Objective 1.
Key options likely to affect phosphate and nitrate losses will be identified, based on scores previously received from experts during the evaluation of Environmental Stewardship (Boatman et al., 2007), work by IGER and ADAS (especially Cuttle et al., 2006), supplemented by recent literature reviews carried out by CSL for other projects (Parry et al., 2006, Ramwell et al., 2006). The effectiveness of these options in reducing nutrient losses will be estimated, drawing on the summary provided by Cuttle et al., 2006, supplemented by other literature where appropriate. Management plans include a range of measures, and the impact of the management plan will be calculated on the assumption that all these measures are implemented, using the equations developed by Anthony (2006), pp. 33-34.
Objective 2
For options which are generally applicable, such as buffer strips, it will be assumed that they should be implemented as widely as possible. In the case of buffer strips, this would be along all watercourses. The total length of watercourse will be estimated using Mastermap for rivers and streams, and the Countryside Survey for ditches (Brown et al., 2006). For options which are only applicable in certain areas, such as EJ1 and EJ2 (options to protect soils), the appropriate area will be determined as the area where relevant crops are grown or livestock kept (potatoes, sugar beet, maize, brassica fodder crops for EJ1; maize for EJ2), combined with vulnerability of the area to erosion and nitrate leaching (using ‘vulnerability maps’ based on, for example, soil type, slope, rainfall). EJ1 will be appropriate in areas at high erosion risk, EJ2 where maize is grown in areas at low risk. The assessment will be at a 5km2 level, rather than at a field level, due to limitations in the resolution of the data available, but will nevertheless give an estimate of the appropriate amount and locations of these options required to maximise impact.
Objective 3
The estimated impact of optimal uptake on phosphate losses will be estimated at a national scale, and for phosphate, compared with the Defra target of 48%. The progress towards optimal uptake will be determined using current uptake data. For options such as EJ1 and 2, which are only appropriate in certain areas, only the uptake in these areas will be considered. For buffer strips, which may be sited against a variety of types of boundary, the proportion of watercourses currently protected by buffer strips will be estimated from a sample of agreement maps.
References
Anthony, S. (2006). Cost and effectiveness of policy instruments for reducing diffuse agricultural pollution. Final report to Defra, projects WQ0106 and ES0205.
Boatman, N.D., Jones, N.E., Garthwaite, D. & Bishop, J. (2007). Evaluation of the operation of Environmental Stewardship. Final report to Defra, project MA01028.
Brown, C.D., Turner, N., Hollis, J., Bellamy, P., Biggs, J., Williams, P., Arnold, D., Pepper, T. & Maund, S. (2006). Morphological and physico-chemical properties of British aquatic habitats potentially exposed to pesticides. Agriculture, Ecosystems & Environment 113, 307-319.
Cuttle, S., Macleod, C., Chadwick, D., Scholefield, D., Haygarth, P., Newell-Price, P., Harrise, D., Shepherd, M., Chambers, B. and Humphrey, R. (2006) An Inventory of Methods to Control Diffuse Water Pollution from Agriculture (DWPA). Defra Report, project ES0203, 115pp.
Parry, H., Ramwell, C., Bishop, J., Cuthbertson, A., Boatman, N., Gaskell, P., Dwyer, J., Mills, J., Ingram, J. (2006). OBS 03: Quantitative approaches to assessment of farm level changes and implications for the environment, Report to Defra Agricultural Change and Environment Observatory.
Ramwell, C.T., Smart, R.P., Parry, H. & Boatman, N. (2006). Scoping study to assess the possible effects of ES schemes on nutrient losses. Final report to Defra, project no. BD2301.
PART B: Estimating impacts of ELS on key biodiversity indicators.
Background
An evaluation of Environmental Stewardship had recently been carried out by CSL. As part of this project, a modelling process was developed which attempted to estimate the impact of ELS on a range of indicators. The process adopted depended on expert scores for the effectiveness of each option, and estimates of the optimal area required to achieve targets. However, the number of experts able to provide estimates of optimal areas was limited, and so model outputs for most indicators were based on values provided by only one or two expert assessors.
In order to provide greater confidence in estimates of the impacts of ELS it was decided to develop an alternative approach for a few key indicators based on a combination of literature search and expert knowledge as derived from advisory literature etc. to estimate habitat requirements. Results would be validated through consultation, and then provision of appropriate habitats by ELS/OELS options assessed.
Farmland birds are key policy indicators, however a study led by the BTO is examining the impact of ELS uptake on species of conservation concern (Vickery et al., 2007). This study will therefore consider additional biodiversity indicators of conservation concern which are considered likely to benefit from ELS/OELS options, and for which sufficient information is likely to be available to make an assessment of the impact of ELS/OELS uptake.
Objectives
1. To determine the key habitat factors limiting the population of the selected indicators;
2. To estimate the amount of key habitat required to maintain viable populations
3. To identify the relevant options under ELS/OELS which provide the habitat requirements of the indicator species/groups, and the target area for the indicators concerned;
4. To compare habitat provision through ELS/OELS under current and projected uptake with estimated requirements, using the previously developed model.
Methods
After a preliminary literature search and brief discussion with key stakeholders, the following indicators were selected:
Brown hairstreak butterfly
Bumblebees
Arable flora
Butterfly species differ in their requirements with respect to food plants, microclimate etc. The brown hairstreak was selected, with advice from Butterfly Conservation, as a species of conservation concern which could potentially benefit from sympathetic implementation of appropriate ELS/OELS options.
Both bumblebee and rare arable flora species are likely to be limited by similar factors, though there is variation which can be recognised by division into sub-groups (e.g. long- and short-tongued bumblebees, spring- and autumn-germinating plants). For the purposes of assessing the benefits of ELS/OELS, it is considered to be appropriate to use these as groups of species as indicators.
Objective 1.
Relevant literature would be examined to determine the key habitat factors likely to limit the population size of the species concerned. The aim would not be to produce a comprehensive literature review, but to develop an assessment, based on the best evidence available, of the factors which would need to be addressed by ES schemes to maintain or increase populations. Accordingly, the review would include not only journal publications, but also relevant conference publications and reports in the ‘grey’ literature. In addition, appropriate advisory material produced by Defra. Natural England and NGOs would be consulted; this generally combines research evidence with expert judgement where scientific evidence is lacking, and so provides a distillation of the best available knowledge at the time of production. In some cases, advice has been produced specifically on how to use ELS/OELS to benefit these species.
Objective 2
Estimates of the amounts of appropriately managed habitat required to maintain a viable population in the area(s) where the species occurs would be made on the basis of the best available knowledge of (i) known habitat requirements, (ii) areas or lengths of habitat in areas where populations are thriving, (iii) data on home ranges/foraging/dispersal distances, which give a guide to the scale at which the organism uses the landscape. These would then be discussed with appropriate experts in each case, either through meetings or conference calls with the organisations concerned.
Objective 3
Relevant options addressing the habitat requirements identified under objective 2 would be determined and their value discussed with the consultees. We would take the opportunity of reviewing scores for habitat value of different options previously provided, aiming to arrive at a considered consensus view. The appropriate area of interest (i.e. the current or potential range of the species concerned) would also be determined. This would be based initially on known species ranges, using for example Atlas and National Biodiversity Network data, plus any additional local data sources which emerge during the literature searches. This would provide the baseline area of interest, which may be modified where considered appropriate in discussion with consultees, to take account of potential for population expansion where this is considered feasible and/or is a BAP target.
Objective 4
Habitat provision through the ELS/OELS would be compared with that estimated to be required, based on (i) current, and (ii) projected future uptake, assuming 70% of farmland is under the schemes, but with current option uptake frequencies, using the model previously developed. Since provision of habitat outside the current or potential range of the species concerned will not be of benefit to them, assessments will relate to the areas of interest defined under objective 3, both for current and projected future uptake, thus taking account of any bias in spatial distribution uptake. This has already been demonstrated in the case of arable flora, where uptake of relevant options was found to be more likely in Joint Character Areas of greatest interest for this group.
Where the likely provision falls short of requirements, the most effective way(s) of improving the benefits would be discussed.
References
Vickery, J., Chamberlain, D., Evans, A., Ewing, S., Boatman, N., Pietravalle S., Norris, K. & Butler, S. (2007). Predicting the impact of future agricultural change and uptake of Environmental Stewardship on farmland birds. Draft report to Defra and Natural England, July 2007.