Natural and human-influenced forest health challenges do not discriminate. Their impact is felt across the United States, from rural communities to urban and everywhere in between.
Street and park trees often endure harsher conditions, including increased temperatures, drier soil and air and less root space than those found in urban or natural forests. The result? Shorter lifespans, vulnerability to changing conditions and less resistance to pests and disease.
Urban trees and forests are vulnerable to a long list of global challenges.
Threats List
Trees and forests evolved to live through disasters; however, the intensity and level of disturbance have accelerated dramatically. Click on the drop downs below to learn more.
Climate Change
Trees help mitigate the impact of climate change. At the same time, climate change creates risks for urban forests such as higher temperatures, more drought and rising sea levels. Risks vary community by community and site by site.
Wildfire
Climate change is leading to longer and more extreme wildfire seasons.
Warmer temperatures and drier conditions create a more favorable environment for wildfires to ignite and spread. As global temperatures increase, experts expect drier conditions, more fires and greater impacts on people and property in the wildland-urban interface.
Programs like FireWise Communities provide tools and examples of preventative planning from potential wildfire for municipal leaders and individual homeowners.
Sea Level Rise
23 of the 25 most populous U.S. counties are coastal. By the year 2100, NOAA predicts that sea levels might surge as much as 2 meters or more than 6 feet. As sea water infiltrates water tables, salinity will kill all but a few tree species.
Extreme Weather
In 2025, Hurricane Helene caused extensive tree damage in Asheville, North Carolina and a wide swath of neighboring towns. The storm and subsequent flooding uprooted thousands of trees. Notably, medium to large trees, particularly Red oaks and Eastern white pines, were more prone to failure. The loss of tree canopy has increased the city’s vulnerability to floods, fires and extreme heat.
Development
Sometimes, aggressive change comes from removing trees and forests to make way for roads, houses, parking lots and shopping malls. When surrounding groves and stands are removed, soils are compacted and water flow is disturbed, causing the remaining adjacent trees to become more vulnerable to pests and diseases.
Monoculture
Like people, as trees grow older, they become more vulnerable to all sorts of maladies – some simply the consequences of age, others due to changes to the environment in which they’re living.
Protecting trees and urban forests from the spread of invasive pests and diseases takes careful, proactive planning, especially for older or already stressed trees that may be more susceptible.
Resist "Big Number" Planting Initiatives
Trees and urban forests of similar ages and/or species may decline, fail or die around the same time. Organize and stagger tree planting campaigns to create a diversity of ages and species so that there is a decreased surge in maintenance expenses, deficit in ecosystem services and likelihood of pests and diseases impacting a large portion of the tree population.
Carefully Manage Multi-Generational Forests
- Consider potential liability risks and take care to compare costs and benefits of maintaining old trees against planting new trees.
- In the long run, strive for a tapestry of trees of different ages and species. Uneven age distribution is important for sustainability because it spreads out the timing of all management activities – planting, maintenance, removal, and replacement – so they won’t all come due at once.
- Uneven-aged forest stands also help pace the delivery of ecosystem services, or tree benefits, so there will be a steady supply at all times. A newly planted tree needs decades of growth before it can provide the same level of benefits as its elders.
Severe Storms Cost Billions Annually
Year after year, storms and fires grow stronger and more devastating. Since 1980, the number of “billion-dollar” severe storms have increased ten-fold.
Drought-inflamed wildfires have devastated ever-larger swaths of communities, from California to Florida.
Compounding Threats Summary
U.S. Forest Service scientists expect further changes in air temperature, precipitation, aridity, wildfire risk, flooding and sea level rise. These threats overlap with current threats – insects, disease and a host of extreme weather events – many of which are also increasing in strength and frequency.
Compounding Threats Results
With these threats piling upon each other, damage to trees will accelerate. When confronted by this near-perfect storm, trees become weaker, more prone to disease and likely victims to floods, fire and high winds.
