Start Date
3-11-2024 10:00 AM
End Date
3-11-2024 10:09 AM
Abstract
With the arrival of the emerald ash borer (Agrilus planipennis) in the Pacific Northwest, it is suspected that a substantial portion of forested wetlands in the Willamette Valley may transition to scrub-shrub communities with significantly reduced canopy heights. This is due to the expected functional extirpation of Oregon ash (Fraxinus latifolia) and a lack of suitable replacement native tree species adapted to the poorly drained clay soils commonly found in low-lying areas throughout the region. Reduced canopy height will presumably influence the amount of stream shading provided by wetland vegetation in riparian communities, which could negatively impact salmonids and other temperature-sensitive aquatic species. We examined how shading in stream-wetland complexes may be affected by a reduction in local canopy height by taking canopy cover measurements at the thalweg and comparing that to the vegetation height from the most recently published LiDAR data. We found that canopy height was moderately correlated with canopy cover over smaller streams (average wetted width of 8.6 ft) with an R2 of 0.265. These statistical analyses, along with some site-by-site comparisons, indicate that though canopy height is predictive of canopy cover to some extent, it is likely that a mature scrub-shrub community can produce a level of shade comparable to that provided by a forested wetland community for small stream systems.
Subjects
Land/watershed management, Plant ecology, Water quality
Persistent Identifier
https://archives.pdx.edu/ds/psu/41408
Creative Commons License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 License.
Potential Impacts of Emerald Ash Borer (Agrilus planipennis) on Stream Shading from Riparian Plant Communities in Pacific Northwest Ash-Dominated Forested Wetlands
With the arrival of the emerald ash borer (Agrilus planipennis) in the Pacific Northwest, it is suspected that a substantial portion of forested wetlands in the Willamette Valley may transition to scrub-shrub communities with significantly reduced canopy heights. This is due to the expected functional extirpation of Oregon ash (Fraxinus latifolia) and a lack of suitable replacement native tree species adapted to the poorly drained clay soils commonly found in low-lying areas throughout the region. Reduced canopy height will presumably influence the amount of stream shading provided by wetland vegetation in riparian communities, which could negatively impact salmonids and other temperature-sensitive aquatic species. We examined how shading in stream-wetland complexes may be affected by a reduction in local canopy height by taking canopy cover measurements at the thalweg and comparing that to the vegetation height from the most recently published LiDAR data. We found that canopy height was moderately correlated with canopy cover over smaller streams (average wetted width of 8.6 ft) with an R2 of 0.265. These statistical analyses, along with some site-by-site comparisons, indicate that though canopy height is predictive of canopy cover to some extent, it is likely that a mature scrub-shrub community can produce a level of shade comparable to that provided by a forested wetland community for small stream systems.