Fire refugia in late-successional forests Garrett Meigs, Meg - PowerPoint PPT Presentation

Fire refugia in late-successional forests Garrett Meigs, Meg Krawchuk | Oregon State University Forest Health in Oregon: State of the State | 3.1.18 Table Mountain Fire, WA, 2012 (2013)

Fire refugia context • Fire mosaics have key implications for biodiversity and ecosystem services. • Widespread concerns about increasing fire activity, particularly high-severity fire. • Increasing interest in fire refugia among researchers, managers, and policy makers. • Working definition : places that burn less frequently or severely than the surrounding landscape (Krawchuk et al. 2016). Pole Creek Fire, OR, 2012 (2013)

Fire refugia definition Working definition : places that burn less frequently or severely than the surrounding landscape (Krawchuk et al. 2016). Global change context: • Fire refugia are a subset of broader refugia. • Refugia provide protection for something, from something.

Fire refugia definition Working definition : places that burn less frequently or severely than the surrounding landscape (Krawchuk et al. 2016). Global change context: • Fire refugia are a subset of broader refugia. unburned / low severity • Refugia provide protection for something, fire refugia from something. topographic “predictable” Key aspects: fire refugia • Predictability • Persistence persistent topographic fire refugia

Fire refugia definition Working definition : places that burn less frequently or severely than the surrounding landscape (Krawchuk et al. 2016). Global change context: • Fire refugia are a subset of broader refugia. unburned / low severity • Refugia provide protection for something, fire refugia from something. topographic “predictable” Key aspects: fire refugia • Predictability • Persistence persistent topographic • Scale: species vs. landscape pattern fire refugia

Fire refugia mapping • Landsat: go-to satellite for mapping fire effects • (R)dNBR: go-to metric to assess change from pre- to post-fire • Monitoring Trends in Burn Severity (MTBS): go-to source • Pre-fire composition and structure are critical

Landscape context: Table Mountain MTBS

Landscape context: Table Mountain MTBS 24%

Landscape context: Table Mountain MTBS with forest mask 24%

Nonforest land cover matters Table Mountain Fire, 2012 (2013)

Nonforest land cover matters Table Mountain Fire, 2012 (2013)

What is the forest composition and structure of refugia? Approach: • Fire perimeters from Monitoring Trends in Burn Severity (mtbs.gov). • Landsat imagery from LandTrendr algorithm (Kennedy et al. 2010). • Severity thresholds from US Forest Service inventory data (Reilly et al. 2017).  % change in basal area: 0-10, >10-25, >25-75, >75-90, >90-100 • Pre-fire forest composition and structure based on Gradient Nearest Neighbor maps (GNN; Ohmann et al. 2012).

Pacific Northwest study area

Study area and selected fires ( n = 99)

Some forest types have more refugia than others Burn severity across selected PNW fires with ≥50% forest ( n = 99) 200,000 200,000 Very high Burn severity extent (ha) Very high Burn severity extent (ha) 150,000 High 150,000 High Moderate Moderate 100,000 100,000 Low Very low / Low 50,000 50,000 unchanged Very low / 0 0 unchanged NONFOREST Other PSME-TSHE Subalpine Mixed-conifer PIPO JUOC NONFOREST Other PSME / Subalpine Mixed- PIPO JUOC TSHE conifer GNN forest type GNN forest type

Some forest types have more refugia than others Burn severity across selected PNW fires with ≥50% forest ( n = 99) 200,000 200,000 Very high Burn severity extent (ha) Very high Burn severity extent (ha) 150,000 High 150,000 High Moderate Moderate 100,000 100,000 Low Very low / Low 50,000 50,000 unchanged Very low / 0 0 unchanged NONFOREST Other PSME-TSHE Subalpine Mixed-conifer PIPO JUOC NONFOREST Other PSME / Subalpine Mixed- PIPO JUOC TSHE conifer GNN forest type GNN forest type

Some forest types have more refugia than others Burn severity across selected PNW fires with ≥50% forest ( n = 99) 200,000 200,000 Very high Burn severity extent (ha) Very high Burn severity extent (ha) 150,000 High 150,000 High Moderate Moderate 100,000 100,000 Low Very low / Low 50,000 50,000 unchanged Very low / 0 0 unchanged NONFOREST Other PSME-TSHE Subalpine Mixed-conifer PIPO JUOC NONFOREST Other PSME / Subalpine Mixed- PIPO JUOC TSHE conifer GNN forest type GNN forest type

Some forest types have more refugia than others Burn severity across selected PNW fires with ≥50% forest ( n = 99) 200,000 200,000 Very high Burn severity extent (ha) Very high Burn severity extent (ha) 150,000 High 150,000 High Moderate Moderate 100,000 100,000 Low Very low / Low 50,000 50,000 unchanged Very low / 0 0 Burn severity across selected PNW fires with ≥50% forest ( n = 99) unchanged NONFOREST Other PSME-TSHE Subalpine Mixed-conifer PIPO JUOC 100 100% GNN forest type Burn severity extent (%) 90% Very high Burn severity extent (%) 80% 75 70% High 60% Moderate 50 50% 40% Low 30% 25 Very low / 20% unchanged 10% 0 0% NONFOREST Other PSME-TSHE Subalpine Mixed-conifer PIPO JUOC NONFOREST Other PSME / Subalpine Mixed- PIPO JUOC TSHE conifer GNN forest type GNN forest type

Some forest types have more refugia than others Burn severity across selected PNW fires with ≥50% forest ( n = 99) 200,000 200,000 Very high Burn severity extent (ha) Very high Burn severity extent (ha) 150,000 High 150,000 High Moderate Moderate 100,000 100,000 Low Very low / Low 50,000 50,000 unchanged Very low / 0 0 Burn severity across selected PNW fires with ≥50% forest ( n = 99) unchanged NONFOREST Other PSME-TSHE Subalpine Mixed-conifer PIPO JUOC 100 100% GNN forest type Burn severity extent (%) 90% Very high Burn severity extent (%) 80% 75 70% High 60% Moderate 50 50% 40% Low n = 99 fires 30% 25 across OR Very low / 20% unchanged and WA from 10% 2004 to 2015 0 0% NONFOREST Other PSME-TSHE Subalpine Mixed-conifer PIPO JUOC NONFOREST Other PSME / Subalpine Mixed- PIPO JUOC TSHE conifer GNN forest type GNN forest type

Forest structure affects the distribution of low- and high-severity fire Burn severity across selected PNW fires with ≥50% forest ( n = 99) 250,000 250,000 Very high Burn severity extent (ha) Burn severity extent (ha) Very high 200,000 200,000 High High 150,000 150,000 Moderate Moderate Low 100,000 100,000 Low Very low / 50,000 unchanged 50,000 Very low / 0 0 unchanged Nonforest Sparse Open Closed w/ small Closed w/ Closed w/ big NONFOREST Sparse Open Closed, small Closed, Closed, big trees medium trees trees a trees medium trees trees GNN structural condition GNN structural condition

Forest structure affects the distribution of low- and high-severity fire Burn severity across selected PNW fires with ≥50% forest ( n = 99) 250,000 250,000 Very high Burn severity extent (ha) Burn severity extent (ha) Very high 200,000 200,000 High High 150,000 150,000 Moderate Moderate Low 100,000 100,000 Low Very low / 50,000 unchanged 50,000 Very low / 0 0 unchanged Nonforest Sparse Open Closed w/ small Closed w/ Closed w/ big NONFOREST Sparse Open Closed, small Closed, Closed, big trees medium trees trees a trees medium trees trees GNN structural condition GNN structural condition

Forest structure affects the distribution of low- and high-severity fire Burn severity across selected PNW fires with ≥50% forest ( n = 99) 250,000 250,000 Very high Burn severity extent (ha) Burn severity extent (ha) Very high 200,000 200,000 High High 150,000 150,000 Moderate Moderate Low 100,000 100,000 Low Very low / 50,000 unchanged 50,000 Very low / 0 0 unchanged Nonforest Sparse Open Closed w/ small Closed w/ Closed w/ big NONFOREST Sparse Open Closed, small Closed, Closed, big trees medium trees trees a trees medium trees trees GNN structural condition GNN structural condition

Forest structure affects the distribution of low- and high-severity fire Burn severity across selected PNW fires with ≥50% forest ( n = 99) 250,000 250,000 Very high Burn severity extent (ha) Burn severity extent (ha) Very high 200,000 200,000 High High 150,000 150,000 Moderate Moderate Low 100,000 100,000 Low Very low / 50,000 unchanged 50,000 Very low / 0 0 Burn severity across selected PNW fires with ≥50% forest ( n = 99) unchanged Nonforest Sparse Open Closed w/ small Closed w/ Closed w/ big 100% trees medium trees trees 100 Burn severity extent (%) 90% GNN structural condition Burn severity extent (%) Very high 80% 75 70% High 60% Moderate 50% 50 Low 40% Very low / 30% 25 unchanged 20% 10% 0 0% Nonforest Sparse Open Closed w/ small Closed w/ Closed w/ big NONFOREST Sparse Open Closed, small Closed, Closed, big trees medium trees trees trees medium trees trees GNN structural condition GNN structural condition