comparing losses and gains in biodiversity: lessons learnt ... · lessons learnt from hs2 phase one...

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.


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)


Key requirements for an HS2 metric (2)

4

Isolated fragment Core area or corridor


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.


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


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


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


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).


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.


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;


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)


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

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


Acknowledgements

14

• 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)


Further information and contact details

15

• Technical Note: Methodology for demonstrating no net loss in

biodiversity is an appendix to the Scope and Methodology report

addendum. Available @

https://www.gov.uk/government/uploads/system/uploads/attachment_dat

a/file/260153/Vol5_Scope_and_methodology_report_addendum_CT-

001-000.2.pdf

• Email contact - [email protected]

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/260153/Vol5_Scope_and_methodology_report_addendum_CT-001-000.2.pdf

mailto:[email protected]

comparing losses and gains in biodiversity: lessons learnt ... · lessons learnt from hs2 phase one...

Documents