1. CRITERION B: RESTRICTED GEOGRAPHIC DISTRIBUTION THEORY AND EXAMPLES
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2. Model of Ecosystem Risk Assessment
Spatial Symptoms
Threatening
processes
Risk of loss
of characteristic
native biota
Ecosystem distribution
Ecosystem function
D Altered biotic
B Small
distribution
A Declining
C Degradation
of abiotic
environment
E Quantitative
risk analysis

3. Criterion B: Restricted distribution
Identifies ecosystems whose distribution is so restricted that they are at risk of collapse from the chance occurrence of a single or few interacting threatening events

4. Criterion B: Restricted distribution
Estimating spatial extent
Risk spreading against spatially explicit threats
In widely distributed ecosystems, risk from spatially explicit threats is spread across multiple independent patches
NOT true if distribution is restricted

5. Risk spreading
Magnitude of ‘insurance effect’ depends on the extent and configuration of ecosystem relative to the spatial extent of threatening processes

6. Criterion B: Restricted distribution
Assumptions
Spatial extent is informative about future risks
Ecosystems with restricted distributions have:
Less capacity to spread risks posed by spatially explicit threats (insurance effects, contagion-percolation theory)
Less capacity for rescue processes, e.g. dispersal & recolonization (metapopulation theory)
Distribution size is context-dependent on spatial features of threats

7. Criterion B: Restricted distribution
Two standard spatial risk-spreading metrics:
Polygons (EOO)
Grids (AOO)
Measures the spatial spread of risk, NOT an estimate of mapped area
Use of non-standard measures invalidates comparison against criteria thresholds

8. Criterion B: Metrics Extent of occurrence (EOO)
Minimum convex polygon enclosing all extant occurrences

9. Criterion B: Metrics Extent of occurrence (EOO)
Minimum convex polygon enclosing all extant occurrences
Area of occupancy (AOO)
Number of occupied 10 x 10 km grid cells
Can exclude small fragments (1% occupancy rule)
Scale-sensitive
Standardised method of (spatial) estimation
Broad/fine ecosystem units

10. Coarser scale ~ larger area estimate
Criterion B: Metrics
Area estimates depend on map scale (cf. grid cell size)
Standard methods of area measurement needed to ensure consistency: 10 x 10 grid cells
Coarse scale
544 km2
Fine scale
348 km2
Medium scale
416 km2
Coarser scale ~ larger area estimate

11. Criterion B: Metrics Extent of occurrence (EOO) Minimum
convex
polygon
c.5,000 km2
10km cells
occupied (46)
occupied >1% (12)
Endangered:
B1 & B2
Extent of occurrence (EOO)
Minimum convex polygon enclosing all extant occurrences
Area of occupancy (AOO)
Number of occupied 10 x 10 km grid cells
Can exclude small fragments (1% occupancy rule)
Scale-sensitive
Standardised method of (spatial) estimation
Broad/fine ecosystem units

12. Criterion B: Metrics Threat-defined location
Extent of occurrence (EOO)
Minimum convex polygon enclosing all extant occurrences
Area of occupancy (AOO)
Number of occupied 10 x 10 km grid cells
Can exclude small fragments (1% occupancy rule)
Scale-sensitive
Standardised method of (spatial) estimation
Broad/fine ecosystem units
Threat-defined location
Geographically or ecologically distinct area in which a single threatening process can rapidly affect occurrences of an ecosystem

13. Criterion B: Metrics Threat-defined location
Geographically or ecologically distinct area in which a single threatening process can rapidly affect occurrences of an ecosystem
Portion of the distribution simultaneously affected by one threatening process.
Relative to the spatial extent of the most serious plausible threat.
Size depends on area covered by the threatening process
NOT # of sites. IS # of spatially independent events that could threaten the ecosystem type
26 patches
4 locations
26 fragments
4 locations

14. Criterion B: Restricted distribution
B. Restricted geographic distribution indicated by ANY OF B1, B2 or B3:
Subcriterion
Measure of geographic distribution CR EN VU B1
Extent of a minimum convex polygon (km2) enclosing all occurrences (extent of occurrence, EOO) is:
≤ 2,000
≤ 20,000
≤ 50,000
AND at least one of the following (a-c):
(a) An observed or inferred continuing decline in ANY OF:
i. a measure of spatial extent appropriate to the ecosystem; OR
ii. a measure of environmental quality appropriate to the characteristic biota of the ecosystem; OR
iii. a measure of disruption to biotic interactions appropriate to the characteristic biota of the ecosystem.
(b) Observed or inferred threatening processes that are likely to cause continuing declines in geographic distribution, environmental quality or biotic interactions within the next 20 years.
(c) Ecosystem exists at:
1 threat-defined location
≤ 5 threat-defined locations
≤ 10 threat-defined locations B2
The number of 10×10 km grid cells occupied (area of occupancy, AOO) are:
≤ 2
≤ 20
≤ 50
AND at least one of a-c above (same as for B1). B3
A very small number of threat-defined locations (generally fewer than 5) AND prone to the effects of human activities or stochastic events within a very short time period in an uncertain future, and thus capable of Collapse or becoming Critically Endangered (CR) within a very short time period (B3 can only lead to a listing as Vulnerable, VU).

15. Threatening process causing continuing decline w/in next 20 years
Criterion B: Restricted distribution
B1 and/or B2
Continuing decline
Threatening process causing continuing decline w/in next 20 years
Number of locations B3
# locations AND capable of becoming CR or CO very quickly
If there are no plausible threats, do not consider locations at all

16. Criterion B: Restricted distribution
Criterion B can only be met if EOO/AOO thresholds are met AND subcritera are met.
Subcriteria distinguish ecosystems that are restricted & stable from those that are restricted & declining.
Subcriteria only require qualitative evidence (no thresholds, except for # of locations)
Includes fragmentation, landscape condition models, and other summary variables

17. Criterion B: Examples
Type of Mesophytic deciduous broad-leaved and mixed coniferous-broad-leaved forests

18. Criterion B: Examples
Area = 260 km²

19. Criterion B: Examples EOO = 589 km² Area = 260 km²
Extent of Occurrence (EOO): ability to spread risk over contiguous areas
EOO = 589 km²
Area = 260 km²

20. Criterion B: Examples EOO = 589 km² = CR B1?
Must first check to see if at least one of the subcriteria are met – must meet both EOO AND subcriteria
EOO = 589 km² = CR B1?

21. AOO = 9 Criterion B: Examples 9 of 11 grid cells ≥1 km² occupied
Area of Occupancy (AOO):
Ability to spread risks among occupied patches
9 of 11 grid cells ≥1 km² occupied
AOO = 9
<1 km²
<1 km²

22. Criterion B: Examples AOO = 9 = EN B2?
Must meet both AOO AND subcriteria
AOO = 9 = EN B2?

23. Criterion B: Examples
Type of Mesophytic deciduous broad-leaved and mixed coniferous-broad-leaved forests

24. Criterion B: Examples

25. Criterion B: Examples
Extent of Occurrence: ability to spread risks over contiguous areas
EOO = 53,310 km²

26. Criterion B: Examples
Extent of Occurrence: ability to spread risks over contiguous areas
EOO = 53,310 km² = B1 (subcriteria)

27. Criterion B: Examples
Area of Occupancy: 84 of 91 grid cells >1% occupied
AOO = 84 grid cells = B2

28. Criterion B: Examples
EOO = 53,310 km² = B1
AOO = 84 grid cells = B2

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