Delaware County’s Silent Forest Invaders: How Non-Native Trees Are Quietly Transforming Your Backyard Ecosystem
Your Delaware County landscape may harbor hidden threats that are slowly but steadily overtaking Pennsylvania’s native forests. Invasive tree species have become one of the most pressing environmental challenges facing homeowners and land managers across the region, with invasive species presenting one of the most significant and urgent threats to American’s forests, according to the American Society of Foresters.
The Most Problematic Invaders in Delaware County
Several invasive tree species have established themselves throughout Delaware County, each posing unique challenges to local ecosystems. Norway maple (Acer platanoides), a common street and lawn tree that frequently escapes cultivation, and Princess-tree, empress-tree (Paulownia tomentosa), imported from China this purple-flowered tree has spread across southern Pennsylvania by winged seeds, are among the most widespread invaders.
Tree of Heaven (Ailanthus altissima), native to China and parts of Asia, is an aggressively spreading deciduous tree common in southeastern Pennsylvania. Tree of Heaven is also the preferred home to spotted lanternfly, an invasive pest species that is decimating agriculture in our area. This dual threat makes Tree of Heaven particularly problematic for Pennsylvania property owners.
Other significant invasives include Callery or bradford pear (Pyrus calleryana), which has established populations in fields and hedgerows in southeastern Pennsylvania, and Siberian elm (Ulmus pumila), a fast-growing tree reaching 50-70 feet high.
Why These Trees Are Dangerous to Native Forests
Invasive trees don’t just compete with native species—they fundamentally alter forest ecosystems. Norway maples pose a problem for native understory plants that cannot compete with the relatively fast-growing Norway maple. Studies have shown significantly less species diversity underneath Norway Maples when compared to areas underneath native maples. This is likely attributed to drier, shadier conditions under Norway maples, but some studies have also suggested Norway maples release allelopathic chemicals into the soil that inhibit the growth of other plants.
The impact extends beyond individual trees. Seeds from mature Norway maple trees can invade nearby forested landscapes where they displace and outcompete native vegetation over time. This undesired spread leads to less food sources and degraded habitats for local wildlife and insect populations.
Safe and Effective Removal Methods
Successfully removing invasive trees requires understanding their biology and growth patterns. Due to its extensive root system and resprouting ability, tree-of-heaven is difficult to control. Treatment timing and following up in the second year are critical to success. Mechanical methods, such as cutting or mowing, are ineffective, as the tree responds by producing large numbers of stump sprouts and root suckers.
For Norway maple, young trees can be removed manually by pulling or digging out the root system. Seedlings can easily be hand-pulled in their first year of growth. Large areas dominated by young seedlings can be easily controlled by mowing. Larger trees and saplings may be cut at ground level with power or manual saws.
Chemical control methods are often necessary for established trees. To control tree-of-heaven, target the roots with systemic herbicides applied in mid- to late summer (July to onset of fall color) when the tree is moving carbohydrates to the roots. Recommended herbicides include glyphosate, triclopyr, and imazapyr. This herbicide application can be used on Norway maples in any season, but be cautious during very cold temperatures when herbicide can freeze and be less effective or difficult to work with.
When to Call Professional Tree Services
While small seedlings can be managed by homeowners, larger invasive trees require professional expertise. Cut stump, stem-injection, and basal bark herbicide treatment are all effective and can be applied during most times of the year outside of early spring when sap is flowing upward. Professional Tree Removal Delaware County PA services have the equipment, knowledge, and safety protocols necessary to handle complex removals safely.
V Serranos Landscaping LLC has been serving Upland and the surrounding Delaware County area with comprehensive landscape services. We understand the specific challenges of Pennsylvania properties – from clay soil issues to seasonal weather extremes. What sets us apart is our combination of design expertise and practical maintenance knowledge. Their approach focuses on creating sustainable landscapes that improve over time. Our team focuses on one thing: delivering results that make sense for your property and your lifestyle. No overselling, no unnecessary complications – just professional landscaping that works.
The Pennsylvania Replace-ive Program
Pennsylvania has recognized the invasive species problem and launched initiatives to help property owners. The Pennsylvania Invasive Replace-ive Program was a great success in 2025 that gave and others the option to remove invasive trees and shrubs from their property and replace them with native trees. Removing invasive plants will help reduce the likelihood of these species becoming unwanted “escapees” into neighboring properties, parks, and forests, and native trees help diversify the urban landscape. Property owners are encouraged to remove one or more invasive species and receive up to (5) FREE, healthy, native, young replacement trees.
Prevention and Long-term Management
Early detection is an advantage in managing any invasive species. Whenever possible, plants should be controlled before they begin producing seed at around 10 years of age. If control is undertaken when seed is present, it is best not to remove plant material from the site to avoid spreading seed.
Property owners should regularly inspect their landscapes for invasive species, especially in areas close to where the species has been or still is popular as a street or yard tree. Professional landscape companies like V Serranos Landscaping can help identify problematic species during routine maintenance visits.
Moving Forward: Protecting Delaware County’s Forest Heritage
The battle against invasive tree species requires coordinated effort from homeowners, professionals, and government programs. V Serranos Landscaping combines design expertise with practical maintenance knowledge, which means creating landscapes that look great and stay manageable. Our team understands local soil conditions, climate challenges, and what actually works long-term in Pennsylvania. Projects are planned with realistic maintenance requirements in mind, so you’re not stuck with high-maintenance features that become problems later. The goal is enhancing your property in ways that make sense for your lifestyle and budget, not just creating something that looks good initially.
By taking action now to identify and safely remove invasive tree species, Delaware County residents can help preserve the region’s native forest ecosystems for future generations while maintaining beautiful, functional landscapes that truly belong in Pennsylvania.