OFFSETs Biodiversity Offsets: Testing a Possible Method for Measuring Biodiversity Losses and Gains at Bardon Hill Quarry, UK

Helen Temple*, Bob Edmonds CEnv MIEEM**, Bill Butcher MIEEM*** and Jo Treweek CEnv MIEEM*** *The Biodiversity Consultancy **SLR Consulting ***Treweek Environmental Consultants

proposed method on a real-world example • aquatic of a tributary of the Introduction – the proposed extension of Bardon Hill River Sence; Quarry in Leicestershire. iodiversity offsets can be • ponds and Sphagnum pools (a Local Bdefined as ‘measurable In this particular case study, offsets Biodiversity Action Plan ); were designed qualitatively through conservation outcomes resulting • terrestrial invertebrate populations; an Environmental Impact Assessment from actions designed to and compensate for significant (EIA). The mitigation and compensation measures described below were residual adverse biodiversity • protected fauna, including badgers, presented in the planning application to six species of bats, breeding birds, impacts arising from project reduce and offset predicted biodiversity reptiles, and amphibians, including a development after appropriate impacts. Quantitative loss-gain measures great crested newt population. prevention and mitigation following the Treweek et al. (2010) method measures have been taken’ (BBOP were fitted to the data post-hoc, to Predicted Impacts 2009). The goal of biodiversity test the method and to seek additional Habitat loss, fragmentation and isolation offsets is to achieve no net evidence that the offsets and other through land-take was the major mitigation and compensation measures loss (or preferably a net gain) impact identified, with a total of 138 proposed were of an appropriate nature of biodiversity on the ground. ha, approximately 27% of the site area, and magnitude to compensate for residual being lost or heavily disturbed by quarry Biodiversity offsets are required losses. operations. A total of five non-statutory by law in a number of countries proposed Local Wildlife Sites and five (reviewed by Biodiversity Neutral Case Study: Bardon Hill parish designated sites would be lost as a Initiative 2005, McKenney and Quarry result of the proposals. Kiesecker 2010), and have been Other impacts identified included effects adopted voluntarily by a small The case study is a proposed extension to on flora and fauna through habitat loss, but growing set of private sector Bardon Hill Quarry, Leicestershire, owned fragmentation and isolation; noise and companies with ‘no net loss’ or by Aggregate Industries UK Ltd (Holcim visual disturbance; impacts resulting from ‘net positive impact’ policies (e.g. Group). Application has been made for changes in air quality caused by dust or Rio Tinto 2004 and 2008, TEEB planning permission for a 66 ha extension, pollutants; alterations to groundwater, 2010). The potential for greater yielding 130 mT of pre-Cambrian rock surface water flow and quality and also over the next 50 years. The application impacts associated with the proposed use of biodiversity offsets in the has been submitted but not yet approved. restoration scheme. UK and the EU is currently being Bardon Hill is a 500 ha estate consisting investigated (Defra 2009, EU mainly of low-intensity pasture and arable, Mitigation and Compensation 20101). with woodland and lowland heath. (Offsets) Measures Proposed A key aspect of biodiversity offsetting Ecological Baseline Conditions Specific biodiversity mitigation and is the quantification of biodiversity compensation measures proposed by the losses and gains. This poses significant Baseline ecological surveys undertaken in developer include commitments to habitat challenges because of the inherent 2007-2009 identified a long list of valued translocation for hedgerows, lichen- complexity of biodiversity, and the variety ecological receptors, including: covered rocks and lowland wet grassland; of ways in which its components can be • Bardon Hill Site of Special Scientific mitigation for protected species, including measured (e.g. area of a habitat, species Interest (SSSI); amphibians, badgers and bats; restoration diversity of an ecological community, and land management of the Bardon Hill population size of a species). Methods are • semi-natural grassland habitats, Estate under a more extensive Biodiversity needed that are transparent, rigorous, including damp neutral grasslands Action Plan than the current version; and and that adequately capture the different (NVC MG4) and dry hay meadows the commitment to manage a degraded aspects of biodiversity whilst remaining (NVC MG5); lowland heathland site outside the estate. straightforward to apply in practice. In • species-rich hedgerows; The biodiversity mitigation and offsets the last issue of In Practice (September for the project were designed by the EIA 2010), Treweek et al. proposed a possible • uncommon lichens on acidic rock outcrops and dry-stone walls; Team (SLR Landscape and Ecology, and method for quantifying biodiversity losses Aggregate Industries) and identified three and gains that might be appropriate for • wet woodlands, mature plantation types of potential biodiversity gains at the UK context. This paper tests the and ancient woodland habitats; Bardon Hill Quarry:

In Practice December 2010 11 BIODIVERSITY OFFSETs

• ‘Restoration gains’; i.e. habitat re- Table 1. Offset scoring matrix created on areas totally cleared by  quarrying and associated activities. Biodiversity Distinctiveness  Very Low (0) Low (2) Medium (4) High (6) • ‘On-site offset gains’; i.e. on-site areas Optimum (4) 0 8 [0.33] 16 [0.67] 24 [1.00] not directly impacted by quarrying Good (3) 0 6 [0.25] 12 [0.50] 18 [0.75] that will be brought under appropriate Moderate (2) 0 4[0.17] 8 [0.33] 12 [0.50] conservation management and Condition Poor (1) 0 2 [0.08] 4 [0.17] 6 [0.25] that are subsequently predicted to improve in condition. Table 2.2. Biodiversity Biodiversity losses losses and and offset offset credits credits required. required • ‘Off-site offset gains’, i.e. off- 

site areas (Ratchett Hill) that will   be brought under appropriate  score credits  conservation management and Total  Phase IHS area Arealost that are subsequently predicted to 1 1 improve in condition. 1code Habitattype code (Ha)  (Ha)  Condition Distinctiveness Matrix Offset required 1.Phase1habitats Offsets for two particularly high value A1.1.1 BroadͲleavedSemiͲnaturalWoodland WB3 16.4 1.3(8%) Good 3 0.75 1.0 habitat types found on site, lowland A1.1.2 BroadͲleavedPlantationWoodland WB0 53.9 0 Moderate 2 0.33 0 wet grassland and lowland heath, are A1.3.2 BroadͲleavedMixedPlantation WB1 26.8 0 Moderate 2 0.33 0 discussed in more detail below. A2.1 Dense/ContinuousScrub WB2 4.0 1.0(25%) Good 2 0.5 0.5 Offset for Lowland Wet Grassland A2.2 ScatteredScrub UH0 1.7 0.3(18%) Good 2 0.5 0.15 B1.1 UnimprovedAcidGrassland GA1 0.1 0.1(100%) Poor 3 0.25 0.02 Approximately 1 ha (26%) of the total area B2.1 UnͲimprovedNeutralGrassland GN1 8.3 1.7(20%) Moderate 3 0.5 0.85 of MG4 grassland identified would be lost B2.2 SemiͲimprovedNeutralGrassland GNZ 1.0 0 Moderate 2 0.33 0 as a result of the development. To offset B4 ImprovedGrassland GI0 60.0 26.4(44%) Poor 1 0.08 2.1 for the loss of this habitat the following B5 Marsh/MarshyGrassland GNZ 0.9 0.8(89%) Poor 2 0.17 0.14 measures have been proposed: B6 PoorSemiͲimprovedGrassland GI0 85.2 12.6(15%) Poor 1 0.08 1.1 • the creation of new neutral wet C1.1 Bracken(Continuous) BR0 0.1 0.1(100%) Moderate 1 0.17 0.02 grassland habitats in the new stream C3.1 TallRuderal UH0 12.7 0 Moderate 1 0.17 0 corridor; D1.1 AcidicDryDwarfShrubHeath HE1 1.4 0.1(7%) Moderate 3 0.5 0.05 F1 Swamp EM1 0.2 0 Good 3 0.75 0 • restoration and enhancement of G1 StandingWater AS41 2.0 0.2(10%) Moderate 3 0.5 0.1 approximately 8 ha area of semi- I1.1.1 Acid/NeutralNaturalInlandCliff RE111 0.2 0.1(50%) Good 3 0.75 0.07 natural grasslands throughout the 2.Specifichabitattypesandotherbiodiversityfeaturesofconservationconcern study area; and NVCMG4Dampneutralgrassland n/a habitatsofhighconservationvalue GN1 3.8 1(26%) Good 3 0.75 0.75 • enhancement, through spreading n/a Continuoushedge LF11 12651 7517 Moderate 2 0.33 2480 green hay, of retained existing wet n/a Importanthedge(HedgeRegs1997) LF111 7678 4202 Good 3 0.75 3151 grassland fields within the estate (this n/a AncientsemiͲnaturalwoodland WB3 11.6 0 Good 3 0.75 0 has already commenced). n/a Plantationonancientwoodlandsites WB3 22.5 0 Poor 2 0.17 0 1 The developer also proposes to minimise Orlengthinmetresforhedgerows residual losses of lowland wet grassland lowland heathland, mature oak and birch 3 habitat such as ‘unimproved neutral by translocating damp neutral grassland woodland, and natural rock outcrops. grassland’ habitat). (NVC MG4 community) turves from existing habitats to an agreed donor site, Losses and gains were projected for all and by translocating soils of species- Quantifying major habitat types at the site (based rich grassland types, including a small Biodiversity Losses and on Phase 1 habitat classification (JNCC area of soil currently supporting a dry 2003), converted to standardised meadow (NVC MG5) community. This Gains Integrated Habitat System categories2). work would be undertaken several years Additionally, losses and gains were prior to agreed extraction to ensure some Post-project offset analysis was projected for specific habitats and success before loss. undertaken by SLR Consulting and The biodiversity features of conservation Biodiversity Consultancy to explore the importance, for example NVC MG4 Offset for Lowland Heath: Ratchett utility of a simple metric to quantify grassland, ancient woodland and Hill biodiversity losses and gains predicted in hedgerows. Losses and gains were the EIA. The analysis seeks to answer the measured using the Treweek . The like-for-not-like offset at Ratchett et al question of whether ‘no net loss’ would be (2010) metric of 3 Hill became available following a review Area x Condition x reached within 25 years, the timeframe (Table 1). of the developer’s other landholdings Distinctiveness of the project’s Biodiversity Action Plan in the area and through stakeholder management commitment. Assessing Habitat Condition discussions. It is proposed to bring 7.5 ha of derelict lowland heathland into active In the Treweek et al. (2010) system, Current habitat condition at Bardon Hill management at Ratchett Hill. A 2009 the main ways to generate measurable and Ratchett Hill was assessed based on survey identified less than one hectare of biodiversity gains are by improving the expert judgement. It would in theory be open heathland habitat remaining, with condition of a particular habitat (e.g. by possible to draw on established methods the majority of site supporting secondary bringing a degraded lowland heathland to assess habitat condition, such as birch woodland and bracken. The aim of into appropriate management) or by those used on nationally designated management, principally the selected elevating distinctiveness category (e.g. sites (Natural England 2008), but for clearance of trees and a change in grazing by converting a Category 1 habitat such the purposes of the present analysis we patterns, would be to create a mosaic of as ‘improved grassland’ to a Category concluded that expert judgement was

12 In Practice December 2010 BIODIVERSITY OFFSETs

sufficient to classify areas of habitat Table 3. RestorationRestoration gains gains (habitat (habitat re-created re-created on areason areas totally totally cleared cleared by quarrying by into four broad condition categories – quarryingand associated and activities).associated activities) optimum, good, moderate and poor.

Assessing Habitat Distinctiveness Estimated Areatobe condition Offset There are no universally agreed methods restored in+25 Matrix credits for assessing levels of biological Habitattype (Ha)1 years Distinctiveness score gained distinctiveness in the UK. A consultation 1.Phase1habitats exercise is currently underway within the BroadͲleavedPlantationWoodland 64 Moderate 2 0.33 21.1 framework of the Natural Capital Initiative4 UnimprovedAcidGrassland 10.6 Moderate 3 0.5 5.3 to test the extent to which consensus UnͲimprovedNeutralGrassland 4 Moderate 3 0.5 2 can be reached if ecologists assign UK SemiͲimprovedNeutralGrassland 5.5 Moderate 2 0.33 1.8 habitats to distinctiveness categories a AcidicDryDwarfShrubHeath 10.6 Moderate 3 0.5 5.3 priori and without in depth assessment StandingWater 2 Moderate 3 0.5 1 on a case-by-case basis. The preliminary 2.Specifichabitattypesandotherbiodiversityfeaturesofconservationconcern results from this consultation were NVCMG4Dampneutralgrassland used to assign different habitat types a habitatsofhighconservationvalue 1.0 Moderate 3 0.5 0.5 distinctiveness score from 0 to 3, where Continuoushedge 3300 Moderate 2 0.33 1089 for example a score of zero would be 1Orlengthinmetresforhedgerows assigned to hard surfaces, or ‘technotope’ (e.g. as applied by Kyläkorpi et al. 2005) Table 4.4. “Balance ‘Balance sheet” sheet’ showing showing losses losses due due to mining to mining and predictedand predicted gains duegains to and a score of 3 to BAP and Annex 1 duerestoration to restoration and offsets and that offsets are predicted that are to predicted accrue over to 25 accrue years (theover management 25 years (the 5 habitat categories (EU Habitats Directive ). managementcommitment of thecommitment Bardon Hill Biodiversityof the Bardon Action Hill Plan). Biodiversity Action Plan) Balance Sheet: Losses and Gains RestorͲ OnͲsite OffͲsite Net Net The area of habitat to be lost, multiplied by ation offset offset position position the score from the Treweek et al. matrix Losses gains gains gains (if1:1 (if3:1 (Table 1) gives the credits, or ‘habitat Arealost1 (offset (offset (offset (offset ratio ratio units’ required for the offset. If several Habitattype (Ha) credits) credits) credits) credits) req’d) req’d) habitat types are present, the assessment 1.Phase1habitats        BroadͲleavedSemiͲnatural must be repeated for each one and the Woodland 1.3(8%)Ͳ1.03.82.8 0.9 results summed to give the overall offset BroadͲleavedPlantationWoodland 0 0.0 21.1 9.230.3 30.3 requirement. To achieve ‘No Net Loss’, BroadͲleavedMixedPlantation 0 0.04.64.6 4.6 the offset must deliver an overall ratio Dense/ContinuousScrub 1.0(25%)Ͳ0.5Ͳ0.5 Ͳ1.5 of 1:1 (or better) when offset gains are ScatteredScrub 0.3(18%)Ͳ0.2Ͳ0.2 Ͳ0.5 1b.Phase1woodlandhabitats 2.6(2.5%)Ͳ1.6 21.1 17.5 0.0 37.0 33.7 compared with the predicted losses due UnimprovedAcidGrassland 0.1(100%) 0.0 5.35.3 5.2 to development. In some projects, the UnͲimprovedNeutralGrassland 1.7(20%)Ͳ0.9 2.0 1.72.8 1.1 offset ratio is set to be greater than 1:1 to SemiͲimprovedNeutralGrassland 0 0.0 1.8 0.22.0 2.0 account for temporal loss and uncertainty. ImprovedGrassland 26.4(44%)Ͳ2.10.0Ͳ2.1 Ͳ6.3 Marsh/MarshyGrassland 0.8(89%)Ͳ0.10.0Ͳ0.1 Ͳ0.4 There are different ways of setting the PoorSemiͲimprovedGrassland 12.6(15%)Ͳ1.07.86.8 4.8 appropriate ratio, for example through 1c.Phase1grasslandhabitats 42(26.8%)Ͳ4.1 3.8 9.6 0.0 14.6 6.4 the use of multipliers (e.g. three units of Bracken(Continuous) 0.1(100%) 0.00.0 Ͳ0.1 TallRuderal 0 0.00.0 0.0 compensation are required for every one AcidicDryDwarfShrubHeath 0.1(7%) 0.1 5.3 0.3 3.8 9.3 9.2 unit lost), or through the use of economic Swamp 0 0.00.0 0.0 time discounting models. Multipliers are StandingWater 0.2(10%) 0.1 1.0 0.00.9 0.7 simpler to apply but can be somewhat Acid/NeutralNaturalInlandCliff 0.1(50%) 0.1Ͳ0.1 Ͳ0.2 arbitrary, whereas time discounting rates 1d.TotalͲallPhase1habitats 138(27%) 0.2 6.3 0.3 3.8 61.8 49.8 can in theory be set based on empirical 2.Specifichabitattypesandotherbiodiversityfeaturesofconservationconcern   NVCMG4Dampneutralgrassland data, although for biological systems habitatsofhighconservationvalue 1(26%) 0.75 0.5 0.70.5 Ͳ1.1 these data are often lacking. An alternative Continuoushedge 7517 2481 1089 873Ͳ519 Ͳ5480 solution for dealing with temporal loss and Importanthedge 4202 3152869Ͳ2282 Ͳ8585 uncertainty, although one that would not AncientsemiͲnaturalwoodland 0 02.92.9 2.9 apply for this particular case study, would Plantationonancientwoodland sites 0 0  3.024  3.0 3.0 be for the gains to already have been 1Orlengthinmforhedgerows achieved through ‘habitat banking’ (e.g. Briggs et al. 2009). The results of the loss are losses, these are outweighed by much offset for the continuous hedgerows at and gains analyses are shown in Tables larger gains in a similar but more ‘valued’ least by increasing the length of new 2-4. Table 4 gives the balance of losses habitat type. For example, there is a small hedge to be planted (important hedgerows versus gains, both for a standard 1:1 ratio residual loss of ‘improved grassland’, but cannot be replanted from scratch). and for a 3:1 ratio (which was arbitrarily this is outweighed by gains in ‘unimproved However, the developer and restoration set to test the consequences of using a neutral grassland’ and ‘unimproved acid design team decided upon a restoration multiplier). grassland’. The most obvious exception principally to woodland and heathland is for hedgerows. Assuming that a 1:1 habitats in response to local stakeholder Discussion and offset ratio is required, there would be a consultation and landscape character residual loss of -2,282 ‘units’ (condition assessment, e.g. The National Forest Conclusions x distinctiveness x length in metres) for Landscape Strategy. important hedgerows and -519 units for In order to compensate for predicted The analysis showed that ‘no net loss’ other continuous hedgerows. In this case, residual losses in hedgerows, gains in would be achieved for most habitat types it would in theory have been possible for other habitats such as dwarf shrub heath at Bardon Hill. In most cases where there the developer to propose a ‘like for like’

In Practice December 2010 13 BIODIVERSITY OFFSETs

(a Biodiversity Action Plan habitat), broad- semi-improved and improved neutral JNCC (2003) Handbook for Phase leaved woodland, unimproved grassland, grasslands are compared to the 1 habitat survey: a technique for and other compensation measures unimproved neutral grassland type. In environmental audit. proposed, are considered a ‘like for not this way improved grassland is assessed Kyläkorpi K, Rydgren B, Ellegård A, like’ offset. as poor condition for the neutral Miliander S, Grusell E (2005) The Biotope grassland type; rather than assessing This paper provides the first ‘field test’ Method 2005. A method to assess improved grassland as being habitat in of the Treweek et al. (2010) method for the impact of land use on biodiversity. optimum condition for fattening cows. In measuring biodiversity losses and gains Vattenfall, Sweden. practice, our interpretation was such that in the context of biodiversity offsets improved grassland could only achieve McKenney BA and Kiesecker JM (2010) and demonstrates that the method can a condition score of Poor–Moderate and Policy Development for Biodiversity be successfully applied to a real-world semi-improved grassland Poor–Good. Offsets: A Review of Offset Frameworks. example. Several issues and points for This approach avoided an apparent 45: 165-176. discussion that the authors noted are Environmental Management, overstatement of the biodiversity value of briefly discussed below. agricultural grasslands. Natural England (2008) SSSI condition First, it is worth noting that the ‘area x assessment: A guide for owners and . NE 61 Natural England, distinctiveness x condition’ metric (or a occupiers Peterborough. similar metric) can be applied to other Notes kinds of biodiversity features, not just Rio Tinto (2004) Rio Tinto’s biodiversity 1 http://ec.europa.eu/environment/ habitats. In the present study, a similar strategy. London, UK and Melbourne, metric ‘length x distinctiveness x condition’ enveco/index.htm Australia. was used for hedgerows. 2 Integrated Habitat System (HIS) was used Rio Tinto (2008) Rio Tinto and because it encompasses all UK terrestrial, Second, distinctiveness category scores biodiversity: Achieving results on the freshwater and marine habitats, including broad-leaved semi-natural woodland with a ground. http://www.riotinto.com/ higher value than broad-leaved plantation. European and BAP habitats (www.ihs. documents/ReportsPublications/ This may be the case for long-established somerc.co.uk). It is also now widely used RTBidoversitystrategyfinal.pdf semi-natural woodland, but may be difficult at local and regional scales for mapping to justify in terms of woodland creation. and collating habitat data recorded in SERC (2007) Integrated Habitat System It is typical for created woodland in other classifications e.g.( Butcher 2008, Regional Dataset for SE England, South restoration schemes to be planted, usually SERC 2007). East England Local Records Centres. Somerset Environmental Records Centre, using a mix of native species. However, 3 Or length x condition x distinctiveness in Wellington. the methodology suggests that higher the case of hedgerows scores for offsetting can be gained from TEEB (2010) The Economics of 4 www.naturalcapitalinitiative.org.uk woodland allowed to naturally regenerate, Ecosystems and Biodiversity. Report for as it is a more distinctive habitat. 5 Council Directive 92/43/EEC of 21 Business - Executive Summary 2010. Dependent upon individual situations, May 1992 on the conservation of natural Treweek J, Butcher B and Temple HJ e.g. distance from existing semi-natural habitats and of wild fauna and flora woodlands and proximity of seed sources (2010) Biodiversity offsets: possible of non-native , woodland methods for measuring biodiversity losses creation using plantation may, in the 25- and gains for use in the UK. In Practice, References year term we are considering here, lead 69: 29-32. to a higher quality woodland than natural Biodiversity Neutral Initiative (2005) regeneration. Environmental Offset Policies, Principles, and Methods: A Review of Selected This article represents the personal view Third, when estimating habitat condition Legislative Frameworks. http://www.forest- of the authors, using data in the public in the Bardon Hill Quarry example, several trends.org/biodiversityoffsetprogram/ realm collected by Aggregate Industries issues required careful thought to ensure a library/new/Environmental%20Offset%20 UK Ltd to support its current planning pragmatic outcome: Legislative%20Frameworks%20DRAFT%20 application. This article is not intended to ‘Optimum’ condition implies that the March%2 030.pdf influence or prejudge the outcome of this habitat is in the best possible state; a application. Briggs BDJ, Hill DA and Gillespie R (2009) condition that rarely is achieved in the Habitat banking - how it could work in the real world. For the example presented, UK. Journal for Nature Conservation, 17: we have interpreted this category Correspondence: 112-122. pragmatically, using it where a habitat [email protected] could be considered to be in favourable Business and Biodiversity Offsets condition and is stable or improving (using Programme (BBOP) (2009) Biodiversity terminology defined by Natural England for Offset Design Handbook. BBOP, condition assessments of SSSIs). Washington, D.C. http://bbop.forest- trends.org/guidelines/odh.pdf In the UK, it is difficult to avoid ‘condition’ and ‘distinctiveness’ scores Butcher B (2008) Regional Habitat being conflated to a degree, because Data Project, Stage 2. West Midlands management is often the main factor Biodiversity Partnership, unpublished determining distinctiveness. This was report. particularly apparent when considering condition scores for grassland habitats. Defra (2009) Scoping study for the design We decided that the condition of heavily and use of biodiversity offsets in an English man-modified agricultural grasslands Context. Final Report, Contract NEE 0801. should use the semi-natural habitat equivalent as a reference mark; i.e. all

14 In Practice December 2010