Seedling Release and Young-Stand Thinning as a Way to Increase Forest Health and Production

View the project final report

Commodities

• Additional Plants: trees

Practices

• Crop Production: forestry, forest/woodlot management
• Education and Training: workshop

After timber harvest, Washington’s forestland owners face a task that has become increasingly tricky: re-establishing a new generation of trees on recently logged sites. New trees have always faced competition from native understory plants, but in recent years, they’ve also had to contend with invasive species such as Himalayan blackberry (Rubus armeniacus) and with dry summers punctuated by heat waves, aggravating the impact of moisture competition from shrubs and grasses. Pressure from invasive species and stress from excessive heat are expected to increase (Lipton et al. 2018 and Vose et al. 2018). Heat stress also makes it especially important to thin overcrowded young stands, so that more soil moisture is available for crop trees.

To help forestland owners address these challenges, Northwest Natural Resource Group proposes to partner with six forest producers to examine varied approaches to improving young stands’ prospects in their early years. Through our project, “Seedling Release and Young-Stand Thinning as a Way to Increase Forest Health and Production,” we will collaborate with producers to devise field trials of new prescriptions for brush control and young-stand thinning, and develop controlled experiments that we will implement, monitor, and analyze for the first 2.25 years of the project. We will then hold two workshops for 50 forest producers to share our findings and view them in situ; disseminate the results through fact sheets and on-line videos, and provide 15 site visits for interested producers to help them apply our findings to their situation.

Our project will result in a clearer understanding of how to release forest seedlings from competition with other species and each other, and will translate to more effective forest management, increased forest health, and improved producer profitability by avoiding the need to replant outcompeted seedlings and enabling trees to reach commercial maturity sooner.

1. Evaluate the cost of at least three treatments to release conifer seedlings from competition by shrubs and grasses. We will write specifications describing the treatments, so they can be compared consistently across treatment areas, and monitor the cost of implementation on the sites where they are used. (August 2019 to September 2021)
2. Evaluate the effectiveness of those treatments by monitoring seedling survival and growth on a total of at least 10 treatment areas after one and two growing seasons have elapsed since treatment. (April 2020 to October 2021)
3. Analyze whether the more intensive treatments are cost effective, based on the data from (1) and (2). (October 2021 to January 2022)
4. Evaluate the effectiveness of young-stand thinning at reducing mortality rates among the remaining stand. (October 2019 to October 2021)
5. Disseminate the findings from (3) and (4) to at least 65 forest producers in person. (January to March 2022)
6. Reach an additional 1200 forest producers with the conclusions of our work through additional media, such as our newsletter and online presentations. (February to May 2022)
7. Conduct follow-up surveys among at least 120 forest producers in western Washington to determine whether the results of our study have influenced their management decisions.