Forest Health Monitoring in Friendship Hill National Historic Site

Cinnamon fern (Osmundastrum cinnamomeum) fiddleheads.

NPS

The majority of Friendship Hill National Historic Site (FRHI) is forested, and these forests are critical park resources that perform many important functions. Forests in FRHI create habitat for hundreds of species of plants and animals, maintain soil stability, and protect water quality. Besides providing beautiful landscapes for people to recreate in, forests also influence our weather and reduce some gases that contribute to climate change.

Monitoring Helps Protect Park Forests

An Eastern Rivers & Mountains Network biologist lays down a tape measure in preparation for forest health monitoring. Forest health monitoring involves collecting data on canopy trees, tree regeneration, shrubs, plant diversity, downed logs, and soil.

NPS

Since 2007, the Eastern Rivers & Mountains Network (ERMN) has been monitoring forest health at FRHI by collecting data on canopy trees, tree regeneration, shrubs, plant diversity, downed logs, and soil at permanent monitoring plots. Specifically, they collect data from 20 plots over a 4-year rotation, such that each plot is visited every 5th year.

One reason that monitoring forest health is so important is that the forests are constantly changing. Storms, pests, pathogens, drought, and new species all play a role in shaping the forest. Studying the different components of a forest gives the ERMN information on the health of the forest, and allows park managers to make better informed decisions on how to manage the forest. In particular, mortality (how many trees are dying), recruitment (how many trees are growing into the canopy), and tree growth are important indicators of forest health and vitality.

“How are park forests changing over time in relation to weather, climate, landscape dynamics, invasive species, deer browse, and natural processes such as disturbances and succession?”

Invasive Species Impact Forest Health

Multiflora rose is one of the most abundant invasive species in Friendship Hill National Historic Site.

NPS

Invasive plant species are a serious threat to the forest in FRHI. The park contains the most invasive plant species (as measured by total cover and number of invasive plant species per plot) of any network park. Multiflora rose (Rosa multiflora), Japanese honeysuckle (Lonicera japonica), Japanese stilt grass (Microstegium vimineum), Oriental lady’s thumb (Polygonum caespitosum), and tree of heaven (Ailanthus altissima) are the most abundant invasive species in the park. Without strategic management, these species will spread further, displacing native species and disrupting the forest ecosystem.

Tree Seedlings Tell of a Changing Forest

The current canopy is dominated by tuliptree (Liriodendron tulipifera), sugar maple (Acer saccharum), red maple (Acer rubrum), black cherry (Prunus serotina), and boxelder (Acer negundo). Of these species, only box elder and sugar maple are well represented in the seedling layer and have current tree recruitment. Tuliptree, a pioneer tree that reproduces poorly under a closed canopy, is very underrepresented in the seedling layer and has mortality greater than recruitment.

Tree species composition differs between forest canopy and seedling layer in Friendship Hill National Historic Site.

Ash seedlings (Fraxinus spp.) are disproportionately abundant in the seedling layer compared to the canopy, but these seedlings are not likely to survive to maturity due to the emerald ash borer (Agrilus planipennis), an invasive insect that kills ash trees.

Frequent browse by over-abundant white-tailed deer is a major cause of tree regeneration failure in Friendship Hill National Historic Site.

NPS

Many parts of the park (more than half the monitoring plots) do not contain enough tree seedlings and saplings to replace the forest canopy. In these stands, large trees will not be quickly replaced when they die and the forest will take longer to re-establish after disturbances. Frequent browse by over-abundant white-tailed deer (Odocoileus virginianus) is a major cause of regeneration failure in the park.

For More Information

ERMN tracks forest health in a total of 360 permanent monitoring plots set up throughout eight national parks. It gathers information on tree health, forest regeneration, plant diversity, invasive species, and more.

For more information, visit the ERMN Vegetation & Soils webpage.

Or, check out all the sciency details in:

Perles S and Others. 2016. Forest dynamics in national parks in the Eastern Rivers and Mountains Network. Natural Resource Report. NPS/ERMN/NRR—2016/1182. National Park Service. Fort Collins, Colorado

Perles SJ and Others. 2014. Forest health monitoring in the Eastern Rivers and Mountains Network: 2009–2012 summary report. Natural Resource Report. NPS/ERMN/NRR—2014/803. Fort Collins, Colorado