Flammability of Dominant Tree Species Portends Severe Wildfire Risk in the Portland-Vancouver Metro Area
Start Date
3-11-2024 4:00 PM
Abstract
Climate Change increases the occurrence of wildfire globally, largely through enhanced drying of plants which increases their flammability. However, these processes are poorly studied in less fire-prone ecosystems, such as the moist temperate coniferous forests of the Pacific Northwest. Likewise, flammability studies are rarely completed within urban forests. These knowledge gaps limit our ability to appreciate the true fire hazard within our cities and puts our communities at elevated risk of catastrophic wildfires. Recent research at Reed College quantified the shoot-level flammability and tissue moisture of 4 dominant tree species from moist Pacific Northwest forests (Pseudotsuga menziesii, Tsuga heterophylla, Thuja plicata, and Acer macrophyllum) and compared it to 4 tree species from more fire-prone dry forest / woodland types (Pinus ponderosa, Calocedrus decurrens, Sequioadendron giganteum, and Quercus garryana), using a custom-built flammability chamber. We found that our native moist forest species had higher flammability than dry forest species and that moisture status accurately predicts flammability. Leveraging satellite observations of fuel moisture allowed prediction of seasonal flammability of three local natural areas–Forest Park, Reed Canyon, and the Sandy River Gorge. Our model shows that the Sandy River Gorge reaches critical levels of flammability late in the growing season (August), while Reed Canyon reaches highly flammable levels a month earlier (July), and Forest Park remains highly flammable throughout the growing season. Our study provides important information on the timing of local wildfire hazard and reveals a potentially under-appreciated extreme latent fire risk within our largest urban natural park, Forest Park.
Subjects
Climate Change, GIS / modeling, Plant ecology
Persistent Identifier
https://archives.pdx.edu/ds/psu/41400
Creative Commons License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License.
Flammability of Dominant Tree Species Portends Severe Wildfire Risk in the Portland-Vancouver Metro Area
Climate Change increases the occurrence of wildfire globally, largely through enhanced drying of plants which increases their flammability. However, these processes are poorly studied in less fire-prone ecosystems, such as the moist temperate coniferous forests of the Pacific Northwest. Likewise, flammability studies are rarely completed within urban forests. These knowledge gaps limit our ability to appreciate the true fire hazard within our cities and puts our communities at elevated risk of catastrophic wildfires. Recent research at Reed College quantified the shoot-level flammability and tissue moisture of 4 dominant tree species from moist Pacific Northwest forests (Pseudotsuga menziesii, Tsuga heterophylla, Thuja plicata, and Acer macrophyllum) and compared it to 4 tree species from more fire-prone dry forest / woodland types (Pinus ponderosa, Calocedrus decurrens, Sequioadendron giganteum, and Quercus garryana), using a custom-built flammability chamber. We found that our native moist forest species had higher flammability than dry forest species and that moisture status accurately predicts flammability. Leveraging satellite observations of fuel moisture allowed prediction of seasonal flammability of three local natural areas–Forest Park, Reed Canyon, and the Sandy River Gorge. Our model shows that the Sandy River Gorge reaches critical levels of flammability late in the growing season (August), while Reed Canyon reaches highly flammable levels a month earlier (July), and Forest Park remains highly flammable throughout the growing season. Our study provides important information on the timing of local wildfire hazard and reveals a potentially under-appreciated extreme latent fire risk within our largest urban natural park, Forest Park.