Fire Regimes and Forest History in Oregons Dry Forests Climate Fire - PowerPoint PPT Presentation

Fire Regimes and Forest History in Oregon’s Dry Forests Climate Fire Insects and Disease Andrew Merschel, Oregon State University

Reconstructing Historical Fire Regimes

Reconstructing Forest History Fire Tree Establishment

Land Use Changes in Mixed-Conifer Forests (Early 1900s) This image cannot currently be displayed. Selective Logging of Large Fire-Resistant Trees Heavy Grazing Fire Exclusion and Suppression Powell 2011

Dry Forest Tree Ring Fire and Forest Histories 2008

Dry Forest Tree Ring Fire and Forest Histories 2018

What was the historical structure, composition, and development history of Oregon’s Dry Forests? Persistent Ponderosa Pine

What was the historical structure, composition, and development history of Oregon’s Dry Forests? This image cannot currently be displayed. Recent Douglas-fir

What was the historical structure, composition, and development history of Oregon’s Dry Forests? This image cannot currently be displayed. Recent Grand Fir

What was the historical structure, composition, and development history of Oregon’s Dry Forests? Persistent Shade Tolerant

Variable Response to Land Use Change

Response to Land Use Change Varies with Environment S o l a Persistent Ponderosa r Pine R a d i a t i o n Recent Grand Fir Recent Douglas-fir Persistent Shade Tolerant Precipitation and Elevation Average Maximum Temperature

Landscape Fire Reconstruction Across Forest Types Precipitation (in) Annual August 45 1 20 0.5

Historical Fire Size and Frequency Fire Rotation 19 years

Variation in Frequency Among Forest Types Interval (years) 30 25 20 15 10 n = 13 n = 17 n = 22 n = 17 n = 13 Persistent Persistent Recent Persistent Persisten Ponderosa Ponderosa Grand Fir Shade Shade Pine with Tolerant Tolerant Lodgepole with Lodgepol

Take Home Messages Historical fire kept density low across a broad range of forest types. In the absence of fire, there has been far greater change in moister and more productive settings. Historically, fire occurred far more frequently and fire perimeters were much larger. Low severity surface fire was the dominant fire effect in very different forest types from ponderosa pine to mixed-conifer. Infrequent, high severity fire occurred, but it was quite limited in spatial extent.

Variable Response to Land Use Change Fire Exclusion

The Study of Tree Rings (Dendrochronology) Climate Fire Insects and Disease

Ponderosa Pine Recent Douglas-fir Recent Grand Fir Persistent Shade Tolerant

Response to Land Use Change Varies with Environment HOT COLD Persistent DRY WET Ponderosa Pine SLOPED SLOPED Recent Grand Fir Persistent Shade Tolerant TOPOGRAPHY Persistent Persistent Shade Ponderosa Tolerant w Lodgepole w Lodgepole HOT COLD DRY WET FLAT FLAT Lodgepole CLIMATE