No abstract

The intensity and scale of wildfires has increased throughout the Pacific Northwest in recent decades, especially within the last decade, destroying vast amounts of valuable resources and assets. This trend is predicted to remain or even magnify due climate change, growing population, increased housing density. Furthermore, the associated stress of prolonged droughts and change in land cover/land use puts more population at risk. We present results of a multi-phase Extension Fire Program Initiative combining fire model results based on worst-case meteorological conditions recorded at 50 weather stations across Oregon with spatially distinct valuations of resources and assets based on regional ecological and socio-economic conditions. Our study focuses on six different Fire Service Areas covering the state of Oregon. We used a geostatistical approach to find weather stations that provide worst-case meteorological input data on record for representative sub-domains. The results provide regionally distinct assessments of potential value loss by wildfire and show that, depending on the region, 12% to 52% of the highest relative risk areas are on private land. This underscores the need to unite strategies and efforts on the landscape scale by including different landowners, managers, and stakeholders of public land and private land efficiently address wildfire damage protection and mitigation. Our risk assessments closely agreed with risks identified during landscape-scale ground projects.

The influence of adjacent canopy gaps on spatial distribution of epicormic branches and delayed foliage (originating from dormant buds) was investigated in 65-year-old coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco). Sample trees were selected across a broad range of local densities (adjacent canopy gap sizes) from a repeatedly thinned stand in which gaps had been created 12 years prior to our study. Lengths and stem locations of original and epicormic branches were measured within the south-facing crown quadrant, along with extents to which branches were occupied by sequential (produced in association with terminal bud elongation) and (or) delayed foliage. Epicormic branches, while prevalent throughout crowns, contributed only 10% of total branch length and 2% of total foliage mass. In contrast, delayed foliage occupied over 75% of total branch length, accounted for nearly 39% of total foliage mass, and often overlapped with sequential foliage. Canopy gap size did not influence original or epicormic branch length or location. On original branches, larger gaps may have modestly negatively influenced the relative extent of sequential foliage on branches and (or) slightly positively influenced delayed foliage mass. Delayed foliage appears to contribute substantially to Douglas-fir crown maintenance at this tree age, but canopy gap size had a minor influence, at least in the short term.Résumé : L'influence de trouées adjacentes dans le couvert forestier sur la distribution spatiale des pousses adventives et du feuillage tardif (issus de bourgeons dormants) a été étudiée chez le douglas de Menzies (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) côtier âgé de 65 ans. Les arbres échantillons ont été choisis parmi un large éventail de densité locale (taille des trouées adjacentes) dans un peuplement éclairci à plusieurs reprises et dans lequel les trouées avaient été créées 12 ans auparavant. La longueur et la position sur la tige des branches originales et adventives ont été mesurées dans le quadrant de la cime exposé au sud. On a aussi noté dans quelle mesure les branches étaient garnies de feuillage séquentiel (produit à la suite de l'élongation du bourgeon terminal) ou tardif. Les branches adventives, bien que répandues partout dans la cime, représentaient seulement 10 % de la longueur totale des branches et 2 % de la masse totale de feuillage. Par contre, le feuillage tardif occupait plus de 75 % de la longueur totale des branches et représentait près de 39 % de la masse totale de feuillage; il chevauchait souvent le feuillage séquentiel. La taille des trouées n'influençait pas la longueur ni la localisation des branches originales ou adventives. Dans le cas des branches originales, les plus grandes trouées pourraient avoir eu une influence légèrement négative sur l'étendue relative du feuillage séquentiel sur les branches ou une influence légèrement positive sur la masse du feuillage tardif, et possiblement les deux à la fois. Le feuillage tardif semble contribuer substantiellement ...