Pollinator Abundance (PA) is a habitat suitability index for pollinators, measuring how overall favourable a landscape is for the presence and prosperity of insect pollinator populations. The index is expressed on a normalised scale from 0 to 1 (dimensionless) and is calculated using the InVEST methodology (Natural Capital Project, Stanford University). It is the final synthetic indicator of the InVEST Pollinator Model, integrating contributions from Nectar Potential (NP) and Nesting Sites (NS).
PA represents the optimal combination of floral resources and nesting sites: a habitat with high nectar resources (high NP) and numerous suitable nesting sites (high NS) will achieve the maximum PA value. High PA values indicate ecosystems capable of supporting abundant and diverse pollinator populations, with direct positive effects on agricultural production, wild flower pollination and plant biodiversity maintenance (Klein et al., 2007; Potts et al., 2010).
Pollinator abundance is particularly sensitive to land management practices: restoring hedgerows, wildflower meadows and semi-natural habitats can significantly increase PA values, with economic benefits estimated in the billions of euros annually from agricultural pollination services alone (Ricketts et al., 2008).
PA is calculated using the InVEST methodology (Sharp et al., 2020) as a synthetic index combining:
The simplified formula is:
PA = f(NS, FA) = NS · accessible_FA
where accessible_FA is the quantity of floral resources reachable by pollinators from their nesting area, weighted by distance (closer resources carry more weight).
Scale: 0 (unsuitable habitat) – 1 (maximum suitability)
| Code | Name | Provider | Resolution | Availability |
|---|---|---|---|---|
WRD_INVST_99 | InVEST Pollinator Model | Natural Capital Project, Stanford University | — | — |
| Indicator | Unit | Range | Inverted |
|---|---|---|---|
pa | — | [0, 8, 16, 24, 32, 40] | No |
Inverted = No: a higher value indicates greater habitat suitability for pollinators and better conditions for biodiversity.
| Level | PA | Interpretation |
|---|---|---|
| A (Excellent) | > 32 | Optimal habitat; high pollinator abundance and diversity expected |
| B (Good) | 24 – 32 | Good suitability; landscape overall favourable to pollinators |
| C (Moderate) | 16 – 24 | Average suitability; partially favourable habitat with some limitations |
| D (Poor) | 8 – 16 | Low suitability; significant limitations in nectar or nesting sites |
| E (Critical) | 0 – 8 | Unsuitable habitat; severe lack of floral resources and nesting sites |
| Indicator | Code | Description | Relationship with PA |
|---|---|---|---|
| Nectar Potential | np | Nectar produced in the area (kg/ha/yr) | NP feeds FA which determines PA |
| Nesting Sites | ns | Suitability of areas for nesting (0–1) | NS directly determines PA |
| Pollinator Abundance | pa | Habitat suitability index for pollinators (0–1) | — (synthetic indicator) |
pa
Calculated using the InVEST methodology (Sharp et al., 2020) as a synthetic habitat suitability index. Combines Aggregated Floral Resources (FA, derived from Nectar Potential NP) with Nesting Sites (NS). Formula: PA = NS · accessible_FA, where accessible_FA is the quantity of floral resources reachable by pollinators from their nesting area, weighted by distance (decreasing exponential). Requires Land Cover and Element-e processing (PA module, which depends on NP and NS). Scale: 0–1 (normalised index).