Mapping 1995-2019 Douglas-fir mortality & climate, SW Oregon

This webmap depicts general locations (polygons) of Douglas-fir mortality in SW Oregon attributed to the flatheaded fir borer, as mapped during the annual cooperative ODF/USFS aerial detection surveys.   Mortality polygons include a mosaic of live and dead trees and are classified by damage level, from light (4-10%) to very severe (>50%).  While directly attributed to the flatheaded fir borer in the surveys, these mortality detections can be considered to represent Douglas-fir mortality related to the effects of drought and opportunistic insects, principally the flatheaded fir borer.  Also shown is cumulative Douglas-fir mortality from the flatheaded fir borer for the period 1975-2019, based on estimated trees killed per acre in mapped polygons, and averaged for 1 km gridcells.  This layer is useful for identifying mortality “hotspots”.   Other layers include mean annual precipitation (1990-2020), mean annual climatic water deficit (1980-2010), projected 2055 climatic water deficit, and historic vegetation (1936).  The precipitation and climatic water deficit layers can be used to assess near-term Douglas-fir mortality risk and the projected climatic water deficit can be used to assess future mortality risk. 


“Will this Douglas-fir tree live or is it likely to die in the next year or two?” Landowners, silviculturists, and tree marking crews all need to be able to predict, with reasonable certainty, the likelihood that a given tree will survive in the near term. Laura Lowrey, USFS Forest Health Protection and Max Bennett, OSU Extension, are currently monitoring more than 50 individual trees, spread across five sites around the Rogue Valley, to assess individual Douglas-fir survival over time. Monitoring locations include Collins Forest (Sardine Creek), Salt Creek, Britt Woods, Boaz Gulch (Applegate), and 4-Corners (Ashland watershed). Selected trees show some symptoms of decline, such as crown thinning, or of flatheaded fir borer attack (pitch droplets in bark crevices), but appear to fall somewhere between “high probability of surviving at least two years” and “almost certain to die in the very near future”. The intent is to calibrate and validate our individual tree risk rating system. The monitoring protocol is described below. As data become available, the intent is to share it here. Initial measurements were completed in spring 2022; we hope to complete the next series of measurements in spring 2023.


OBJECTIVE: Marking guideline development for trees eminently dead (within 1-3 years) because of Cavitation, FFB and associated agents  


Location of plots and trees

•Select your plot location wherever you suspect FFB and Douglas-fir decline complex.

•Select 5-10 trees per location to photo monitor for three years. Select various tree crown vigor levels (transparency, dieback, greenness) and diameters.

Crown Ratings

Canopy Position, Fine Twig Dieback, Foliage Discoloration, Defoliation – taken from FIA handbook

Tree Vigor – General gut impression when looking at the entire crown health, think of it as a sliding scale (adapted from Keen, F. 1943. Ponderosa pine tree classes redefined. Journal of Forestry 41:249-253).

Symptoms of DF Decline more generally

Stress cones-Abundant cone crop related to the dying tree trying to reproduce and not due to a mast year.

General chlorosis- yellowing of the tree that is different from genetic color differences of DF

Symptoms we are associating with DF Decline cavitation and FFB

Red and yellowing branchlets- scattered throughout crown, typically

Pitch jewels – pea sized droplet of clear sap found only in bark fissures/cracks; jewels will drip down 3 inches from the crack but will be clear. Older yellowed drips aren’t counted in this estimate, just the fresh clear drips

Woodpeckering – woodpecker excavations along the bole, mark for green or yellowing crowns

Witches claw (claw)- fine twigs have lost all needles at the ends of branches; evaluate the outer portion of the crown to get the category of loss.

Photo Monitoring

Take at least 3 photos: bole; crown shooting up next to bole: and, of the entire crown-

Record distance and azimuth to tree;

Record time of day photo was taken

Rate the probability of Mortality within three years based upon the symptoms and severity collectively. 

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