Habitat Creation & Enhancement

This guide covers calculating biodiversity units for habitat creation and enhancement interventions.

Habitat Creation

Habitat creation involves establishing new habitats where none existed before (or replacing a lower-value habitat). Creation calculations include additional multipliers for:

Temporal risk: Time required to reach target condition
Difficulty: Technical difficulty of creating the habitat

Formula

\[\text{Creation Units} = \text{Area} \times \text{Distinctiveness} \times \text{Condition} \times \text{Strategic} \times \text{Temporal} \times \text{Difficulty}\]

Basic Creation Calculation

import pandas as pd
from bngmetric.creation import calculate_creation_bng_from_dataframe

creation = pd.DataFrame({
    'Habitat': ['Grassland - Lowland meadows', 'Wetland - Reedbeds'],
    'Condition': ['Good', 'Moderate'],
    'Area': [3.0, 1.5],
    'Strategic_Significance': [1.15, 1.0]
})

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

Habitat Enhancement

Enhancement improves existing habitat, either by:

Condition enhancement: Improving the condition of the same habitat type (e.g., Poor grassland to Good grassland)
Distinctiveness enhancement: Converting to a higher distinctiveness habitat within the same broad habitat type

Condition Enhancement

For improving condition within the same habitat:

import pandas as pd
from bngmetric.enhancement import (
    calculate_enhancement_bng_from_dataframe,
    calculate_enhancement_uplift_from_dataframe
)

enhancement = pd.DataFrame({
    'Habitat': ['Grassland - Lowland meadows'],
    'Start_Condition': ['Poor'],
    'Target_Condition': ['Good'],
    'Area': [2.0],
    'Strategic_Significance': [1.15]
})

# Post-enhancement units
post_units = calculate_enhancement_bng_from_dataframe(enhancement)

# Net uplift (post - baseline)
uplift = calculate_enhancement_uplift_from_dataframe(enhancement)
print(f"Post-enhancement units: {post_units:.2f}")
print(f"Net uplift: {uplift:.2f}")

Distinctiveness Enhancement

For converting to a higher distinctiveness habitat (within the same broad type):

import pandas as pd
from bngmetric.enhancement import (
    calculate_distinctiveness_enhancement_bng_from_dataframe,
    calculate_distinctiveness_enhancement_uplift_from_dataframe
)

enhancement = pd.DataFrame({
    'Baseline_Habitat': ['Grassland - Modified grassland'],
    'Baseline_Condition': ['Poor'],
    'Target_Habitat': ['Grassland - Lowland meadows'],
    'Target_Condition': ['Moderate'],
    'Area': [2.0],
    'Strategic_Significance': [1.15]
})

units = calculate_distinctiveness_enhancement_bng_from_dataframe(enhancement)
uplift = calculate_distinctiveness_enhancement_uplift_from_dataframe(enhancement)

Understanding Uplift

The uplift represents the net biodiversity gain from an intervention:

\[\text{Uplift} = \text{Post-intervention Units} - \text{Baseline Units}\]

This is the key metric for demonstrating biodiversity net gain.

Using JAX Arrays

For integration with JAX workflows or when processing large datasets:

import jax.numpy as jnp
from bngmetric.creation import calculate_batched_creation_bng_units
from bngmetric.constants import HABITAT_TYPE_TO_ID, CONDITION_CATEGORY_TO_ID

habitat_ids = jnp.array([HABITAT_TYPE_TO_ID['Grassland - Lowland meadows']])
condition_ids = jnp.array([CONDITION_CATEGORY_TO_ID['Good']])
areas = jnp.array([3.0])
strategic = jnp.array([1.15])

units = calculate_batched_creation_bng_units(
    habitat_ids, condition_ids, areas, strategic
)

Disallowed Combinations

Not all habitat/condition combinations are valid for creation or enhancement. Invalid combinations return 0 units (the temporal multiplier is set to 0).

from bngmetric.creation import get_temporal_multiplier

# Check if a creation pathway is valid
temporal_m = get_temporal_multiplier(habitat_id, condition_id)
if temporal_m == 0:
    print("This habitat/condition combination is not valid for creation")