D3438: Five years of foliar insect herbivory on Quercus garryana (Garry Oak) across distinct habitats

Tuesday, November 12, 2024

9:00 AM – 5:00 PM MST

Location: Phoenix Convention Center, Exhibit Hall 6, PCC

Presenting Author(s)

Sienna Painter (she/they)

Researcher
Western Oregon University
Portland, Oregon

Co-Author(s)

HP

Hannah Porter

Western Oregon University
Monmouth, Oregon
CC

Catherine Couture

Biologist
Université du Québec
Montreal, Quebec, Canada
GH

Gareth Hopkins

Associate Professor of Biology
Western Oregon University
Monmouth, Oregon
AH

Ava Howard

Professor of Biology
Western Oregon University
Monmouth, Oregon

Quercus garryana, Garry Oak, has a native range stretching through western North America, hosting hundreds of insect species in unique, distinct habitats ranging from open savannah to dense woodland. Changes in land use have resulted in Q. garryana habitat loss of over 95% with the remaining oaks competing with fast-growing conifers. We aim to understand the long-term patterns of foliar insect damage to mature Q. garryana canopies in multiple habitat conditions, filling an existing knowledge gap. Our research is conducted within four habitat types: dense conifer-oak forest, open oak-savannah, and two habitats undergoing restoration from mixed conifer-oak to a restored oak woodland. We sample mid-canopy foliage from 2-15 trees per habitat each year from 2019 to 2023. Average foliage damage ranged from 3.13% to 44.17% with chewing representing the largest portion of damage, followed by other damage such as necrosis due to insect galls, skeletonizing, and mining. We found significant variation in foliar insect herbivory between years, the temporal effect of which was amplified in some habitats more than others. Insect mining levels were significantly affected by habitat type, however chewing, skeletonizing, and other damage were more heavily influenced by year than habitat. On the canopy samples, we found over ten different species of herbivorous insects including Corythucha arcuata and Neuroterus saltatorius. Recognizing patterns of foliar insect herbivory on Q. garryana will improve our ability to restore oak ecosystems and conserve the native biodiversity Q. garryana amplifies.