CUR - The Council on Undergraduate Research

Reproductive Health of Oregon White Oak Across Multiple Habitats

Henry Roberts, Department of Biology, Western Oregon University, Monmouth, Oregon 97361, Samantha Sackett, Department of Biology, Western Oregon University, Monmouth, Oregon 97361, Oswaldo Moreno, Department of Biology, Western Oregon University, Monmouth, Oregon 97361, Shayla Solomon, Department of Biology, Western Oregon University, Monmouth, Oregon 97361, Ava Howard, Department of Biology, Western Oregon University, Monmouth, Oregon 97361, Gareth Hopkins, Department of Biology, Western Oregon University, Monmouth, Oregon 97361, Jeff Snyder, Department of Biology, Western Oregon University, Monmouth, Oregon 97361,

Oregon white oak (Quercus garryana) is native to the Pacific Northwest, spanning from British Columbia to California. Its distribution has declined by 90% over the past 100 years due to a mix of competition from other species, forest fire suppression, and land conversion for agriculture and settlement. Understanding the factors that influence white oak reproductive health is critical for population recovery. We studied how viability of acorns is related to acorn insect damage and parent tree anatomical and physiological characteristics among three different habitat types that differ in tree competition, and microclimate. In western Oregon, we gathered 822 acorns from 47 study trees in restored oak woodland, oak savannah, and a mixed conifer-deciduous forest. Acorns were separated into germinated and non-germinated categories before undergoing dissection to determine insect presence and tissue damage. We determined that the proportion of germinated acorns for a given tree was positively related to acorn size, and negatively related to the proportion of acorns that were internally and externally damaged by filbert weevils (Curculio occidentis) and filbert worms (Cydia latiferreana). Oak populations will benefit from restoration techniques that decrease filbert insect pests and provide resources to trees to allow production of larger acorns. Future research should test for a possible connection between these factors and controlled burns.

Additional Abstract Information