Collecting Plant Phenology Data in Imperiled Oregon White Oak Ecosystems: Analysis and Recommendations for Metro

Imperiled Oregon white oak ecosystems are a regional conservation priority due to the rich biodiversity they support, including rare and endemic species such as Oregon state-listed endangered pale larkspur (Delphinium leucophaeum). Previously dominant in the Pacific Northwest, upland prairie and oak woodlands are now under significant threat, with only 2% remaining in the Willamette Valley in small fragments. Over the past 150 years, conversion to agriculture, urban development and fire suppression have dramatically reduced and degraded Oregon white oak habitat. Climate change has now emerged as an additional threat, causing observable shifts in plant phenology. In fragile oak systems, a change in phenology may have profound implications for plant community composition, diversity and general ecosystem function. Collecting phenology data is an important research strategy to quantify change within sensitive plant communities. In collaboration with Metro, a three-part project was developed to support ongoing conservation efforts in Oregon white oak habitat. Part one evaluates Metro’s previously collected phenology data on 130 species of forbs and grasses. Part two makes recommendations for improving future phenology data-collection methods. Part three is a collection of scientific vouchers documenting key plant species in varying phases of phenology for Metro’s teaching herbarium. Four main recommendations emerged from this project. To increase efficiency and reproducibility in phenological monitoring, it is necessary for Metro to reduce the number of study species, using selection criteria outlined in the report based on regional and national research. The number of monitoring sites must also be reduced to streamline procedures. To accurately quantify change in phenology, the timing of data-collection visits (from year to year) must be consistent. Finally, adopting monitoring protocol of the National Phenology Network (USA-NPN) will align data metrics with a national standard and promote data-sharing for large scale research and collaboration. Collectively, this project supports the long-term objective of phenological monitoring: to understand how plant populations will respond to climate change. Such data may identify conservation priorities and inform management strategies to strengthen and diversify fragile plant communities and the trophic interactions they support