Embedded Files
Determining the cause of an unsuccessful riparian planting using field data and spatial interpolation
Determining the cause of an unsuccessful riparian planting using field data and spatial interpolation
In 2022 and 2023 McKenzie River Trust constructed two swales on Green Island to help reconnect the Willamette River to the floodplain during high waters. These swales were constructed following historic side channels of the Willamette River detected by lidar. The disturbances caused by the earth moving required the ground be planted with native species or invasive species would take over. The ground was seeded, and volunteers worked to plant a variety of native bare-root forbs and drive willow stakes the winter after construction. While these efforts were generally successful, one section of swale was noticeably struggling. To explore the factors that may have detracted from the success of the planting efforts, I performed a survey. I obtained data on the outcome of all of the flagged plants as well as their planting conditions (mulch?), the outcome and height of the willow stakes along transects, and the general ground cover along transects. Finally I examined the clay content of the soil at several locations.
In 2022 and 2023 McKenzie River Trust constructed two swales on Green Island to help reconnect the Willamette River to the floodplain during high waters. These swales were constructed following historic side channels of the Willamette River detected by lidar. The disturbances caused by the earth moving required the ground be planted with native species or invasive species would take over. The ground was seeded, and volunteers worked to plant a variety of native bare-root forbs and drive willow stakes the winter after construction. While these efforts were generally successful, one section of swale was noticeably struggling. To explore the factors that may have detracted from the success of the planting efforts, I performed a survey. I obtained data on the outcome of all of the flagged plants as well as their planting conditions (mulch?), the outcome and height of the willow stakes along transects, and the general ground cover along transects. Finally I examined the clay content of the soil at several locations.
SoilandFlagged.pdfGreen Island South Swale Survival
Green Island South Swale Survival
The other section of swale runs in a more westerly direction, allowing the tall trees to more amply it. The soil in that section is also much more rich than the soil of the surveyed section, where areas lack sediment altogether.
Based on the data, there is no single clear factor that caused the plants to die off. The north side of the swale ismore exposed to the sun and did see more die off. The soil was mostly rock and sand throughout. The willow stakes that had the most success were shorter, as the tall stakes grew for a season then died off. Independently, mulch was not a factor for success. The most successful planting efforts were the lupine and fescue seedings. Lupine and fescue constitute a plurality of ground cover and other plants had more success when cohabitating with lupine.
Based on the data, there is no single clear factor that caused the plants to die off. The north side of the swale ismore exposed to the sun and did see more die off. The soil was mostly rock and sand throughout. The willow stakes that had the most success were shorter, as the tall stakes grew for a season then died off. Independently, mulch was not a factor for success. The most successful planting efforts were the lupine and fescue seedings. Lupine and fescue constitute a plurality of ground cover and other plants had more success when cohabitating with lupine.
Page updated
Report abuse