CRITERION B: RESTRICTED GEOGRAPHIC DISTRIBUTION THEORY AND EXAMPLES IUCN Red List of Ecosystems Training www.iucnrle.org @redlisteco IUCN Red List of Ecosystems

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

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

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

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

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

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

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

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

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

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

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

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

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).

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

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

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

Criterion B: Examples Area = 260 km²

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

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?

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

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

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

Criterion B: Examples

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

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

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

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

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