bngmetric

An open source Python implementation of the UK’s Biodiversity Net Gain (BNG) Statutory Metric.

Overview

bngmetric provides two complementary capabilities:

Python Implementation of the BNG Metric

A straightforward, validated implementation of the UK’s Statutory Biodiversity Metric. Use it as a drop-in replacement for spreadsheet-based calculations, with the benefits of programmatic access, automation, and integration with existing data pipelines.
JAX-Powered Advanced Analysis

Built on JAX, enabling gradient-based methods for sophisticated analyses that aren’t possible with traditional spreadsheet tools:
- Sensitivity analysis: Compute gradients to understand how changes in area, condition, or habitat type affect biodiversity units
- Uncertainty propagation: Propagate classification uncertainty (e.g., from remote sensing or ecologist assessments) through the metric using probabilistic methods
- Optimisation: Find optimal habitat creation/enhancement strategies subject to constraints

Installation

pip install bngmetric

Or install from source:

git clone https://github.com/pdh21/bngmetric.git
cd bngmetric
pip install -e .

Quick Start

Basic Usage

Calculate biodiversity units for a habitat parcel:

import pandas as pd
from bngmetric.core_calculations import calculate_bng_from_dataframe

# Define baseline habitats
baseline = pd.DataFrame({
    'Habitat': ['Grassland - Lowland meadows', 'Woodland - Lowland mixed deciduous woodland'],
    'Condition': ['Moderate', 'Good'],
    'Area': [2.5, 1.0],
    'Strategic_Significance': [1.15, 1.0]
})

# Calculate baseline biodiversity units
units = calculate_bng_from_dataframe(baseline)
print(f"Baseline units: {units:.2f}")

Habitat Creation

from bngmetric.creation import calculate_creation_bng_from_dataframe

# Define habitat creation proposal
creation = pd.DataFrame({
    'Habitat': ['Grassland - Lowland meadows'],
    'Condition': ['Good'],
    'Area': [3.0],
    'Strategic_Significance': [1.15]
})

units = calculate_creation_bng_from_dataframe(creation)
print(f"Creation units: {units:.2f}")

Off-site with Spatial Risk

from bngmetric.creation import calculate_offsite_creation_bng_from_dataframe

# Off-site creation with spatial risk multiplier
offsite = pd.DataFrame({
    'Habitat': ['Grassland - Lowland meadows'],
    'Condition': ['Good'],
    'Area': [3.0],
    'Strategic_Significance': [1.15],
    'Spatial_Risk': ['Neighbouring LPA/NCA']  # 0.75 multiplier
})

units = calculate_offsite_creation_bng_from_dataframe(offsite)

Contents

User Guide

Advanced Analysis