Comparing losses and gains in biodiversity: Lessons learnt from HS2 Phase One

Transcription

1 Comparing losses and gains in biodiversity: Lessons learnt from HS2 Phase One John Simmons (URS) & David Collins (HS2 Ltd) IEEM Spring Conference, Birmingham 18 th March 2014 Environmental Overview Consultants for HS2 Phase One

2 Overview: HS2 Phase One Phase One = 143 mile route London-West Midlands. Promoted via a hybrid Bill Land required to construct and operate Phase One identified within the hybrid bill. includes compensatory habitat provision Seeking to achieve no net loss at the route wide level No formal offsetting agreements with third parties proposed Use of an offsetting metric to measure pre- and post development biodiversity units Proposed methodology accompanied ES in November 2013, following discussion with Defra & Natural England. Calculation nearing completion. 2

3 Key requirements for an HS2 metric (1) UK Government backed scheme Defra pilot offsetting metric Compatible with scope of habitat survey methodologies agreed for use in HS2 Phase One. Loss of some irreplaceable habitats (principally ancient woodland) & impacts on land within SSSIs desire for an all encompassing calculation. Landscape scale scheme Vital to ensure importance of position in the ecological network considered Source: Lawton et al (2010) 3

4 Key requirements for an HS2 metric (2) Isolated fragment Core area or corridor 4

5 Key modifications to the Defra metric: Distinctiveness 1. Habitat distinctiveness New tier Very high score for Habitats of Principle Importance (HoPI) which cannot be adequately recreated Multiplier of 8 but only available within pre-development calculation Compensation for very high losses will not be like for like but rather via larger areas of high distinctiveness habitat For all other habitats aim to provide habitats of same or higher distinctiveness & similar type. 5

6 Key modifications to the Defra metric: Distinctiveness Distinctiveness Habitat type Multiplier Very High (N.B. ONLY USED IN PRE- DEVELOPMENT CALCULATION Habitats meeting habitat of principal importance definition and which can not be adequately re-created if lost. For HS2 Phase One considered: ancient semi-natural woodland, mature lowland heathland & Lowland fen. 8 High Moderate Low None Habitats of principal importance which do not qualify under the definition for very high category above. Other semi-natural habitats that do not fall within the scope of habitats of principal definitions - includes uncultivated field margins, road verges and railway embankment (excluding those intensively managed) Improved grassland, arable fields (excluding any uncultivated margins), built up area, domestic gardens, regularly disturbed bare ground, intensively managed road verges and rail embankments. Transport corridors (without associated verges), hard standing, landfill sites, spoil heaps

7 Key modifications to the Defra metric: Habitat condition Condition multiplier 3 Good Condition assessment category 2 Moderate 1 Poor N.B. A condition score of 1 will automatically be applied to all habitats of low distinctiveness 2. Habitat condition No variable condition score for low distinctiveness habitats. automatically scored as poor (1). One-step rule replaced by cap on target condition scores for postdevelopment habitats For high distinctiveness habitats - only allowed to target a max. of moderate condition (2) except hedgerows Where habitats not to be primarily managed for their ecological value then mitigation/compensation can target max. condition of moderate (2). 7

8 Key modifications to the Defra Metric: Distinctiveness vs condition` Condition Pilot methodology HS2 methodology Very High (8) Habitat Distinctiveness High (6) Medium (4) Good (3) 24* 18** 12 2 Moderate (2) 16* Poor (1) 8* Low (2) *Not available as post-development targets. ** Only available as post-development target in relation to hedgerows 8

9 Key modifications to the Defra Metric: Position in ecological network Multiplier based on position in ecological network applied to both preand post-development calculations 3 point scoring based on Lawton Review principles of more, bigger, better and joined Bigger & well connected areas of high distinctiveness habitat are valuable and help to maintain and enhance value of existing networks Not intended as a proxy for requirements of individual species Better acknowledge impact of losses in pre-development calculation Seeks to encourage provision of compensation in those locations that make ecological sense In establishing position in the network scores ecologist have considered habitat data available for within a 500m radius of the land required for the Proposed Scheme (i.e. the extent of habitat survey undertaken). 9

10 Key modifications to the Defra Metric: Position in ecological network Pre-Development Position within existing ecological network Habitat areas which form part of a contiguous area of habitat(s) of principal importance which is of more than 1ha in size 1 (core habitat block) and have connectivity with other areas of semi-natural habitat Habitats areas which form part of a contiguous area of habitat(s) of principal importance which is of more than 1ha in size but have little or no connectivity with other areas of semi-natural habitat (i.e. those that do not score multiplier of 3 above); Habitat areas which form part of a contiguous area of habitat(s) of principal importance which is of between 0.25ha and 1ha in size (regardless of connectivity these are considered as stepping stones); Multiplier 3 2 Habitat which forms part of an area of semi-natural habitat which provides continuous physical connectivity 2 between existing core habitat blocks Any other areas which do not meet the criteria identified for either a multiplier of 2 or 3 above. 1 1 For the purposes of the calculation where areas of habitat of principal importance are separated by gaps of nonqualifying habitat of 15m or less then these should be considered to be contiguous (unless professional judgement of an ecologist considers otherwise); 2 Defined as a continuous corridor of moderate, high or very high distinctiveness habitat parcels. A gap in qualifying habitat of more than 15m in extent, or a section where minimum width drops below 5m in width is considered a break in connectivity. 10

11 Key modifications to the Defra Metric: Position in network Post-development multiplier As per pre-development table with one addition Areas of habitat creation or expansion within the aims of a specified Nature Improvement Area (NIA) or Biodiversity Opportunity Area (BOA) scheme also score multiplier of 3; 11

12 Conclusions and lessons learnt (so far.) Metric HS2 modifications represent a natural progression to Defra metric Opportunities for on-going improvement (e.g. condition scoring) Consideration of position in the network can be built into the metric Particularly relevant to linear infrastructure schemes, but can be incorporated for all developments Better acknowledges full impact of losses and focuses minds on providing mitigation in locations that achieve best ecological outcomes Can help achieve progress towards policy goals. Important to place limits/caps within the metric that temper compensation targets to that which is realistic to achieve. IMAGE TO BE INSERTED (TBC) 12

13 Conclusions and lessons learnt (so far.) Undertaking no net loss calculation Vital to get your habitat mapping correct Habitat maps need to clearly differentiate habitats of principal importance Phase 1 vs Integrated Habitat System (IHS) Resource intensive Use GIS to automate the process Difficult to predict all eventualities at this scale Expect to undertake multiple iterations to reach your final answer Condition scoring guidance needs to be further developed to allow it to set management goals Potential to use the calculation throughout the project lifecycle 13

14 Acknowledgements Jo Hughes (URS) Ecology leads at Arup (Oliver Barnett), Atkins (Kat Stanhope/Kate Vincent), The Ecology Consultancy (Jon Riley/Tom McArthur/Matt Wainhouse) and ETM (Beth Costes/Naomi Shepherd) All other consultants involved in undertaking the calculations, associated GIS work and wider HS2 field work. Natural England (Adrian Jowett), Defra (Richard Plant, John Kilner) the Major Infrastructure and Environment Unit (MIEU) (Will Armitage), and all other stakeholders who provided comments on our draft methodologies. Natalie Hall (HS2 Ecology advisor), Mike White (HS2 Environment GIS manager) 14

15 Further information and contact details Technical Note: Methodology for demonstrating no net loss in biodiversity is an appendix to the Scope and Methodology report addendum. a/file/260153/vol5_scope_and_methodology_report_addendum_ct pdf contact - john.simmons02@urs.com 15