Managing Resilient Forests. A Regional Initiative

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Forests in NPS Region 1 are Complex and Important, but Need Help for Long-term Success.

Forests cover tens of thousands of acres in eastern national parks. A recent analysis of over a decade’s worth of five regional Inventory & Monitoring (I&M) Networks data showed that they consistently contained more complex structure and dynamics typical of older forests. Eastern national parks had more large live trees over 2-feet in diameter (about 80% higher than surrounding forests) and wildlife-friendly standing dead large trees. There was also more decomposing tree matter on the forest floor that is vital for many plants and animals, averaging 135% of the volume found in surrounding forests. For more on this study, see the NPS article: National Park Forest – More Than a Pretty Picture.

For the long-term, the same monitoring data identified concerning, region-wide trends in tree regeneration that indicate significant threats to the sustainability of these critical ecoysytems. Park forests are facing a range of interacting stressors including over-abundant white-tailed deer populations, invasive plant invasion, novel pests and pathogens, development of surrounding lands, altered disturbance regimes, increasingly frequent extreme weather events, and changing climate conditions. At worst, these stressors can lead to the replacement of a parks’ native forest with thickets of exotic invasive shrubs that smother wildflowers and other native plants, impede cultural viewsheds, and can increase visitor exposure to disease-carrying ticks. Collectively, these impacts will result in increased costs for visitor safety management and to preserve park infrastructure, and lead to changes in the overall character of a park visitors have enjoyed for generations.

This enormous white ash tree in Vermont's Marsh-Billings-Rockefeller NHP is a good representative of the larger canopy trees found in Eastern national parks. More native canopy species are needed to sustain park forests long-term.

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More Tall Trees, Please.

An abundant regeneration layer containing tree seedlings and saplings (small trees) of varying sizes and of made up of species matching those in the fully grown canopy is an important component of a healthy forest. Many parks lack the minimum levels of seedlings and saplings needed to replace canopy trees as they die, whether from age, fire, extreme weather, or the effects of non-native pests and pathogens. In most parks, non-native plant abundance is increasing as well which further suppresses tree regeneration. Forests that lack sufficient regeneration, or the young species don’t match the current canopy species, suffer from what is called “regeneration debt” (Miller & McGill 2019). The most severe form of regeneration debt is a complete lack of regeneration, which, if allowed to persist, can ultimately lead to loss in forest habitat.The I&M networks of the northeast have launched the Managing Resilient Forests Initiative to raise awareness of threats to forest health and foster collaboration across the region.

Park Forests Have Urgent Management Needs

Based on these troubling trends, I&M scientists are concerned that parks in the Eastern U.S. need active management approaches to restore or sustain their forests over the long term. Managing for resilient park forests is imperative to ensure long-term ecosystem health, maintain biodiversity, and meet the NPS mission of preserving park resources unimpaired for future generations.

For More information

Contact:
Stephanie Perles
Vegetation Ecologist, Eastern Rivers and Mountains Network
(814)-441-9643



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