Understory trees are the often-overlooked layer of a forest that grow beneath the main canopy. In Virginia woodlands, native understory species such as flowering dogwood (Cornus florida), eastern redbud (Cercis canadensis), pawpaw (Asimina triloba), American hornbeam (Carpinus caroliniana), witch hazel (Hamamelis virginiana), serviceberry (Amelanchier laevis), and sourwood (Oxydendrum arboreum) provide disproportionate ecological, aesthetic, and practical value. This article explains the many benefits of retaining and planting native understory trees in Virginia, outlines practical management techniques, and provides concrete species and planting recommendations for different Virginia regions.
Understory trees perform multiple ecological functions that sustain healthy woodlands and native wildlife populations. Their contributions are both direct and indirect, and they operate at scales from soil microbes to regional biodiversity patterns.
Understory trees increase vertical structure and habitat heterogeneity. This structural complexity supports a wider range of bird species, small mammals, reptiles, amphibians, and invertebrates than a two-layer forest with only canopy and ground cover. Many forest-dependent species use specific layers for nesting, foraging, or shelter.
Understory trees are key spring nectar and pollen sources. Flowering dogwood, serviceberry, and redbud bloom early in the season, feeding pollinators when canopy trees have not leafed out. This timing is crucial for native bees, syrphid flies, and early-emerging butterflies.
Understory trees provide critical mast and fruit resources. Pawpaw, serviceberry, dogwood, and sourwood produce fruits eaten by birds, raccoons, foxes, black bears, and small mammals. The seasonal spread of flowering and fruiting among understory species helps sustain wildlife through food-scarce periods.
Understory trees influence nutrient cycling and soil health. Smaller-rooted trees and shrubs often exploit nutrients in the upper soil horizons and contribute fine root turnover and leaf litter with different chemistry than canopy species. This diversity of litter types supports a richer decomposer community and stabilizes nutrient availability across years.
Understory vegetation buffers microclimate extremes. By shading the forest floor and reducing wind speeds within the midstory, understory trees moderate soil temperatures, reduce evaporation, and maintain humidity levels important for seedling recruitment, seedlings of canopy trees, and moisture-sensitive taxa such as salamanders.
Understory trees play a measurable role in water management and erosion control across Virginia’s varied landscapes, from the Piedmont’s rolling hills to the steeper slopes of the Blue Ridge and Ridge and Valley physiographic provinces.
Understory root systems, which often include a dense network of fine roots, help bind surface soils and reduce the risk of erosion on slopes and stream banks. Species like American hornbeam and pawpaw are particularly effective at establishing in streamside or seasonally wet microsites and reducing sediment transport.
By increasing the forest’s interception capacity for rainfall and promoting infiltration, understory trees reduce peak surface runoff during storms. Their leaf litter improves soil structure and porosity, enhancing infiltration and groundwater recharge in systems where stormwater management is a concern.
Healthy native understory contributes to water quality by filtering nutrients and trapping sediments before those materials reach streams. Understory plantings are a recommended element for riparian buffer restoration projects across Virginia to protect trout streams and other sensitive aquatic habitats.
Understory trees are keystone resources for many Virginia woodland species, offering food, shelter, and breeding habitat throughout the year.
Birds: Understory trees support migratory and resident birds. For example, dogwood and serviceberry fruits feed thrushes and waxwings in fall; redbud and serviceberry flowers attract insects consumed by insectivorous birds in spring; dense understory tangles provide nesting and escape cover for species such as towhees, veeries, and ovenbirds.
Mammals: Small mammals rely on understory fruits and dense cover for foraging and predation refuge. Pawpaw fruits are favored by opossums and foxes, and dense pawpaw thickets provide secure bedding areas for fawns and small mammals.
Invertebrates and pollinators: A diverse understory supports specialist host-plant relationships. For example, the pawpaw is the host for zebra swallowtail butterflies; many native bees use early spring blossoms of redbud and serviceberry as key food sources; and understory leaf litter is essential habitat for ground-nesting solitary bees and predatory ground beetles.
Reptiles and amphibians: Cool, humid microclimates maintained by understory vegetation are critical for salamanders and other moisture-sensitive amphibians, which are abundant in Virginia’s forested landscapes.
Plant diversity: Understory trees create light and soil conditions favorable for a suite of native wildflowers, ferns, and shrubs. That plant diversity in turn supports a larger array of herbivores and pollinators, producing cascading biodiversity benefits.
Understory trees contribute to the resilience of woodlands under changing climate and disturbance regimes.
Diversity of tree sizes and life-history strategies increases forest resistance to pests, diseases, and extreme weather. Understory species that leaf out early or retain late-season leaves extend the forest’s photosynthetic period and help stabilize carbon uptake across variable years.
While understory trees store less carbon per individual than larger canopy trees, collectively they add significant living biomass and soil carbon inputs through roots and litter. Maintaining a multi-layered forest increases total standing and soil carbon relative to a simplified canopy-only stand.
Understory plantings can aid natural regeneration after canopy disturbances (windthrow, ice, canopy insect outbreaks) by providing seed sources and nurse plants that shade and protect advanced regeneration of canopy species.
Native understory trees have important non-monetary values for landowners, conservation organizations, and the public.
Aesthetic value: Spring blooms, fall color, and seasonal fruits of understory trees enhance the recreational and scenic value of woodlands. Species such as flowering dogwood are iconic in Virginia landscapes.
Cultural and educational value: Understory species provide opportunities for environmental education about native plants, pollination ecology, and sustainable forest stewardship.
Property-level benefits: Strategically planted understory trees can reduce lawn area, increase privacy along property edges, and stabilize slopes or streambanks, reducing long-term maintenance needs.
Management benefits: Maintaining a robust understory encourages natural regeneration of desirable canopy species, potentially reducing the need for costly planting or timber stand improvement treatments over time.
Despite their benefits, understory trees face pressures in Virginia woodlands. Recognizing common threats helps managers take appropriate protective measures.
Deer browse: White-tailed deer populations in many parts of Virginia have suppressed regeneration of palatable understory species. Deer can prevent recruitment of redbud, dogwood, and pawpaw if protective measures are not taken.
Invasive plants: Invasives such as Japanese stiltgrass, multiflora rose, privet, and bush honeysuckle can outcompete native understory seedlings and reduce regeneration success. Early detection and targeted removal are critical.
Overbrowsing and lack of disturbance: Some understory species require periodic canopy gaps or disturbance for successful recruitment. Complete shading from dense canopy or chronic deer browsing can create recruitment bottlenecks.
Poor planting technique: Planting bare-root or container stock too deeply, failing to water during establishment, or using inappropriate stock size can lead to high mortality in planted understory trees.
Disease and pests: While native species are generally adapted to local pest communities, some can be affected by specific diseases (dogwood anthracnose, for example) or pests. Choosing resistant genotypes and maintaining species diversity mitigates these risks.
This section gives concrete, actionable steps for landowners, land managers, and restoration practitioners working in Virginia woodlands.
Below is a practical list of native understory trees and small trees recommended for Virginia, organized by common habitat affinities. Use these as a starting point for planting plans tailored to your site.
When planning plantings, include a mix of species that bloom and fruit at different times of the year to maximize benefits for pollinators and wildlife and to spread ecological risk.
Native understory trees are a highly cost-effective investment for enhancing the ecological integrity and resilience of Virginia woodlands. They support pollinators, birds, and mammals; stabilize soils and water quality; diversify forest structure and carbon storage; and increase aesthetic and cultural value. Effective management requires site-appropriate species selection, protection from deer and invasives during establishment, proper planting technique, and adaptive monitoring. For landowners and managers seeking to improve forest health and biodiversity in Virginia, reestablishing and maintaining a diverse native understory is one of the highest-return actions available.