White Pine Thinning
White Pine Thinning: Before
Figure 5: Before view looking into the crowns of densely packed white pine trees. Notice the “lollipop” look to the trees with live needles only at the very top. Healthy, vigorous pine trees benefit from having 40% of their total height with live needles, known as live crown ratio.
The current stand is overstocked, meaning trees are growing too closely together and competing for resources; sunlight, water, and nutrients in the soil. The live crown ratio is estimated to be 25%, much lower than the minimum recommended 40%. These conditions limit the growth rate of individual trees and increase stress, making them more susceptible to damage from drought, insects and disease agents. There is a lack of understory vegetation and the ground layer is so thick with pine needles, native tree and shrub seeds have difficulty germinating in the nutrient-poor pine duff. The smallest crowned pines should be removed on one to two sides of the most dominant, healthiest, and vigorous pine trees. This will reduce competition and provide additional resources to the best-growing trees on the site.
White Pine Thinning: After
Figure 6: Post-harvest view of the same white pine thinning harvest designed to reduce competition and increase growth rates and vigor of the remaining trees. Notice that the residual trees have the largest, most-robust crowns and are free to grown on one to two sides of their crowns.
The prescribed thinning treatment removed the poorest quality stems to give the healthiest trees additional resources for better growing conditions. The tree tops now have room to grow and expand horizontally, generally on one to two sides of their crowns. Tree root systems have less competition for water and nutrients providing more of each to the remaining trees. Despite being thinned, there are still enough remaining trees close to each other to protect them from being blown over in windstorms. The thick layer of pine needles on the forest floor was slightly scraped to expose bare mineral soil, allowing native tree and shrub seeds to germinate. The understory has since developed with a variety of native hardwood tree and shrub species providing increased browse and cover for wildlife.
Content last updated December 2020.