PA – Underground Cavities

Biodiversityv06.00 credits/per_km2

Responsible:Niccolò Calandri

PA – Underground Cavities (pa_ns_underground_cavities)

Overview

The PA – Underground Cavities component measures the Pollinator Abundance (PA) specifically associated with pollinators that nest in natural or pre-existing underground cavities. It is expressed on a normalised scale from 0 to 1 (dimensionless index) and is one of the sub-indicators of the InVEST Pollinator Model (Natural Capital Project).

This group includes pollinators that use pre-existing cavities rather than excavating them: abandoned small mammal burrows, crevices between tree roots, rock gaps, and holes left by frost heave or organic decomposition. Species adopting this strategy include bumblebees (Bombus spp.), which commonly nest in rodent burrows, and some solitary bee species that occupy pre-existing ground cavities.

In the overall Nesting Sites (NS) formula, underground cavities carry weight 1, indicating a proportional but less dominant contribution compared to other factors.

Calculation Methodology

Calculated using the InVEST methodology (Sharp et al., 2020). For each land cover pixel, a suitability value for underground cavity presence (0–1) is assigned. The PA value integrates nesting suitability with accessible floral resources (FA), weighted by foraging distance.

Weight in overall NS calculation: 1/13

Scale: 0 (unsuitable habitat) – 1 (maximum suitability)

Data Sources

Code	Name	Provider	Resolution	Availability
`WRD_INVST_99`	InVEST Pollinator Model	Natural Capital Project, Stanford University	—	—

Quality Range and Levels

Indicator	Unit	Range	Inverted
`pa_ns_underground_cavities`	—	[0, 8, 16, 24, 32, 40]	No

Level	Value	Interpretation
A (Excellent)	> 32	Abundant underground cavities; rich ecosystems with active soil fauna
B (Good)	24 – 32	Good availability; burrows and root cavities present
C (Moderate)	16 – 24	Average availability; some cavities present but limited
D (Poor)	8 – 16	Low availability; uniform soils with few natural cavities
E (Critical)	0 – 8	Near absence of cavities; artificialised or sealed environments

References

Sharp, R. et al. (2020). InVEST User's Guide. The Natural Capital Project, Stanford University.
Potts, S.G. et al. (2010). "Global pollinator declines: trends, impacts and drivers". Trends in Ecology & Evolution, 25(6), 345–353.
Goulson, D. (2010). Bumblebees: Behaviour, Ecology, and Conservation. Oxford University Press.

Data Sources & References

Sources

WRD_INVST_99

Methodology

PA component for underground cavities. Calculated using InVEST methodology (Sharp et al., 2020). For each land cover pixel, a suitability value for underground cavity presence (0–1) is assigned. The PA value integrates nesting suitability with accessible floral resources (FA), weighted by foraging distance. Weight in overall NS calculation: 1/13. Scale: 0–1.