Comparing losses and gains in biodiversity: Lessons learnt ... ?· Lessons learnt from HS2 Phase One…

Download Comparing losses and gains in biodiversity: Lessons learnt ... ?· Lessons learnt from HS2 Phase One…

Post on 18-Aug-2018

212 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Comparing losses and gains in biodiversity:

    Lessons learnt from HS2 Phase One

    John Simmons (URS) & David Collins (HS2 Ltd)IEEM Spring Conference, Birmingham

    18th March 2014

    Environmental Overview Consultants for

    HS2 Phase One

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

    Overview: HS2 Phase One

    2

    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.

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

    Key requirements for an HS2 metric (1)

    3

    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 consideredSource: Lawton et al (2010)

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

    Key requirements for an HS2 metric (2)

    4

    Isolated fragment Core area or corridor

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

    Key modifications to the Defra metric: Distinctiveness

    5

    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.

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

    Key modifications to the Defra metric: Distinctiveness

    6

    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 Habitats of principal importance which do not qualify under

    the definition for very high category above.

    6

    Moderate 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)

    4

    Low Improved grassland, arable fields (excluding any uncultivated

    margins), built up area, domestic gardens, regularly disturbed

    bare ground, intensively managed road verges and rail

    embankments.

    2

    None Transport corridors (without associated verges), hard

    standing, landfill sites, spoil heaps.

    0

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

    Key modifications to the Defra metric: Habitat condition

    7

    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 post-

    development 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).

    Condition

    multiplier

    Condition

    assessment

    category

    3 Good

    2 Moderate

    1 Poor

    N.B. A condition

    score of 1 will

    automatically be

    applied to all

    habitats of low

    distinctiveness

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

    Key modifications to the Defra Metric: Distinctiveness vs condition`

    8

    HS2 methodology

    Pilot methodology

    Habitat Distinctiveness

    Very

    High (8)

    High (6) Medium

    (4)

    Low (2)

    Co

    nd

    itio

    n

    Good (3) 24* 18** 12 2

    Moderate

    (2)

    16* 12 8 2

    Poor (1) 8* 6 4 2

    *Not available as post-development targets. ** Only available as post-development target in

    relation to hedgerows

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

    Key modifications to the Defra Metric: Position in ecological network

    9

    Multiplier based on position in ecological network applied to both pre-and 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).

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

    Key modifications to the Defra Metric: Position in ecological network

    10

    Pre-Development

    Position within existing ecological network Multiplier

    Habitat areas which form part of a contiguous area of habitat(s) of principal

    importance which is of more than 1ha in size1 (core habitat block) and have

    connectivity with other areas of semi-natural habitat

    3

    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);

    Habitat which forms part of an area of semi-natural habitat which provides

    continuous physical connectivity2 between existing core habitat blocks

    2

    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 non-

    qualifying 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.

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

    Key modifications to the Defra Metric: Position in network

    11

    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;

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

    Conclusions and lessons learnt (so far.)

    12

    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)

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

    Conclusions and lessons learnt (so far.)

    13

    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

    Diffic