Maintain diversity of native tree species: Restore native tree species

Restore native tree species

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Native tree species in Northeastern forests have evolved regeneration strategies, such as seeding and spouting, which help them reestablish after disturbance. Due to this, the use of artificial regeneration techniques have seldom been needed in this region. However, as climate change is expected to alter hydrology and increase disturbances in our forests, these practices may need to become more common. Temperature and precipitation changes could also increase the prevalence of invasive species, diseases, and wildfire, all of which impact the distribution and diversity of species in our forests. Converting forests to native tree species that are well adapted to the site will increase the forest's resilience in a changing climate.

Two reasons for incorporating native tree planting into management plans are 1) for the diversification of plantations of non-native species, and 2) for addressing when tree mortality outpaces the establishment of new seedlings. Plantations of non-native species, such as red pine and Norway spruce, were established, particularly on town watersheds and state forests, as a part of the Civilian Conservation Corp efforts in the 1930s. Since non-native species are by definition out of their native range, they are typically less vigorous and more susceptible to insects and disease.

The establishment of new seedlings in Northeastern forests can fail to keep pace with tree mortality in natural stands due to conditions created by deer herbivory, invasive species abundance, pest management, forest fragmentation, degraded soils, and other factors. The increase in deer populations and spread of competing invasive plants has made it more difficult for many native tree species to regenerate in our forests. Reducing these stressors by protecting trees from deer browse and removing invasive understory plants can help native trees establish, but in some cases planting can speed up this process. This is especially true where the current tree species in the area are poorly matched with the current and projected future climate of the area. In this case, planting native species can aid in adapting the forest to climate change.

Some examples of how to do this work include regeneration harvests and underplanting. Planting with multiple co-benefits in mind, including biodiversity, can help support ecosystem resilience. These co-benefits are often achieved by assuring a diversity of species and structural complexity in the stand and across the landscape. Understanding your site conditions also helps to determine which species to favor or establish. For example, for sites that are anticipated to become warmer and drier, planting or maintaining drought and heat tolerant species would help to increase the forest’s resilience. These efforts in general can also help to restore function to degraded ecosystems and enhance carbon sequestration potential.