Understory Species Increase Project
Abstract
Fostering a native understory herbaceous layer is key to enhancing overall forest habitat and species diversity; however, few land managers have the technical information or plant materials available to do so. This results in slow or non-existent herbaceous species reestablishment on many restoration projects. The Understory Species Increase Project (USIP) is a collaborative effort started by Portland BES, Clean Water Services, and Metro that aims to fill this gap in resources by researching, developing, and amplifying diverse herbaceous species. The current stage examines which species might work well by seed. Fifty-four trial plots were installed at seven sites throughout the Portland Metro area, selected as seeded or control treatments, and monitored to document species presence and cover. Wilcox tests on data from three years of monitoring supported the hypothesis that seeded plots demonstrate significantly higher rates of successful establishment of target species. This implies that restoration projects will be more successful in establishing native herbaceous species using a seeding technique than allowing natural regeneration alone to recover species in the short term of 1-3 years. Logistic regression from two years post seeding analyzed site-specific parameters of soil moisture, canopy cover, slope and aspect revealed that both slope and soil moisture had a significant effect on vegetative cover and presence. Together with treatment, these predictors account for approximately 35 percent of the variability observed in vegetated cover. This highlights the need for further research to determine what other environmental factors may be influencing herbaceous species establishment in revegetation projects.
Subjects
Habitat restoration, Plant ecology
Persistent Identifier
https://archives.pdx.edu/ds/psu/33828
Understory Species Increase Project
Fostering a native understory herbaceous layer is key to enhancing overall forest habitat and species diversity; however, few land managers have the technical information or plant materials available to do so. This results in slow or non-existent herbaceous species reestablishment on many restoration projects. The Understory Species Increase Project (USIP) is a collaborative effort started by Portland BES, Clean Water Services, and Metro that aims to fill this gap in resources by researching, developing, and amplifying diverse herbaceous species. The current stage examines which species might work well by seed. Fifty-four trial plots were installed at seven sites throughout the Portland Metro area, selected as seeded or control treatments, and monitored to document species presence and cover. Wilcox tests on data from three years of monitoring supported the hypothesis that seeded plots demonstrate significantly higher rates of successful establishment of target species. This implies that restoration projects will be more successful in establishing native herbaceous species using a seeding technique than allowing natural regeneration alone to recover species in the short term of 1-3 years. Logistic regression from two years post seeding analyzed site-specific parameters of soil moisture, canopy cover, slope and aspect revealed that both slope and soil moisture had a significant effect on vegetative cover and presence. Together with treatment, these predictors account for approximately 35 percent of the variability observed in vegetated cover. This highlights the need for further research to determine what other environmental factors may be influencing herbaceous species establishment in revegetation projects.
