Creating Networks of Habitats to Support Wildlife from the Little Things on Up
By Suzy Yetter
Welcome to the 2nd edition of Going Native, designed to help us advance our landscaping practices through ecological friendly approaches that recognize the critical role of native plants and backyard landscaping in maintaining healthy ecosystems. Today, during this frigid February, we’re going to highlight a very important keystone tree species, provide some useful tips for spring planning and planting, and discuss dormant-season activities that can help us prepare for the year ahead.
Keystone Highlights
White Oak (Quercus alba)
Note that while I refer to the white oak, much of the following can be applied to oaks in general.
Let’s talk about the majestic white oak (Quercus alba), a magnificent specimens inof Pennsylvania forests and backyards that hold a special place in many of our hearts. A 2020 article by the Arbor Day Foundation referred to the white oak as the “King of Kings” and no wonder. The reigning state champion white oak measures in at 92 feet tall and 22 feet around, while the “Angel Oak” in South Carolina spans an area of over 17,000 square feet. (And for those of you thinking, “And you want me to plant that in my yard?!” be sure to read on for ways to squeeze even oak trees into small backyard landscapes.) Oak trees, especially white oak trees, are such an iconic part of our history, with individual trees achieving local and even national status. Up until 2017, the oldest known tree, nicknamed the “Holy Oak” from which an entire New Jersey town was built around, had lived through 600 years of change. At a time when Western Europe didn’t even know North America existed, a time when world maps referred to the Atlantic Ocean as the “Dark Unknown” full of mystery and sea monsters, the Holy Oak was quietly growing on the other side of the world. Can you imagine all the history this tree had lived through: wars, natural disasters, people? Fights to save oak trees have been around a long time, too. When 35 acres of maritime forest surrounding the “Angel Oak” of Johns Island, South Carolina were slated to develop more than 600 townhouses and apartments, outraged citizens fought back. Today, those 35 acres are owned and protected by the Lowcountry Land Trust. As a Land Trust concerned with protecting the natural and cultural heritage of Central Pennsylvania, ClearWater has had the pleasure of protecting several iconic oak trees, as well (see the sidebars).
This natural longevity and durability apply to both the landscape and the lumber yard. White oak wood is extremely durable, making white oaks popular for construction, furniture, flooring, wood working, and building strong ships. The USS Constitution was named “Old Ironsides” for the white oak hull that British cannonballs couldn’t penetrate. White oaks can effectively seal off the heartwood by plugging the water-conducting vessels with balloon-like tyloses, making them almost impervious to water. And let’s not forget the oak barrels for wine and spirits. Oaks are so crucial to the Kentucky bourbon industry that Senator Mitch McConnell recently introduced the White Oak Resilience Act of 2025 to conserve and bolster white oak tree populations.
Let’s move on to discuss the ecological aspects of the oak’s durability and longevity across the landscape with some keystone plant highlights. Keystone plants have a disproportionately large ecological impact on their environment relative to their abundance and oaks are the champions, supporting 557 species of caterpillars in the mid-Atlantic region and over 950 species in the United States. Over the past 56 million years oak trees have evolved into 435 species spanning five continents. With all that oaks have to offer and as long as they’ve been around, is it any wonder so many species depend on oak trees to survive? Even fungal networks have coevolved with particular oak species to help create underground ecosystems that fuel above-ground communities. Through this symbiotic relationship with mycorrhizal fungi, oaks can actually help other plant species acquire nutrients and take root. Types of mushrooms commonly found beneath or on oak trees include chanterelles, porcini, morels, chicken of the woods, and turkey tails. Another interesting relationship with oaks is that of Conophilus americana, otherwise known as American cancer-root or bear corn. This uncommon parasitic plant is generally only seen in the spring when the cone-shaped inflorescence appears above ground, usually near the base of an oak tree. It does not photosynthesize and, therefore, does not require sunlight. The majority of the plant is underground, attached to the roots of the host tree, where it forms large galls or tumors on its roots (hence the term “cancer root”).
Oak trees can support a vast multitude of insects, including aphids, plant hoppers, thrips, katydids, grasshoppers, crickets, walkingsticks, beetles, at least 22 species of leaf-tying and leaf-folding caterpillars, and 534 moth and butterfly species, like the banded tussock and pink-striped oakworm moths. Oaks are also the exclusive host plants for over 600 different Hymenoptera species (bees and wasps), particularly sawflies. Let’s not forget all of those acorns and the wildlife they support: deer, raccoons turkeys mice, black bear, squirrels, chipmunks, wood ducks, and even humans in earlier times. Oaks make great cavity trees for birds, such as hairy woodpeckers, bluebirds, and owls. Their flaky bark provides ideal roosting sites for bats.
Important Notes About Oaks
Here are some tips to help maximize the benefits of incorporating oaks into your landscape (or ecologically enhancing existing oaks).
· Plant tree groves, rather than individual trees. By mimicking the space found in most forests, you will produce stronger, healthier trees that are less likely to blow down. Why? Trees interlock their roots, forming a dense matrix of root masses that is extraordinarily difficult to uproot. As Doug Tallamy recommends in his book, The Nature of Oaks, plant trees in twos or threes, maybe on a 6-ft center, creating small groves that the eye will take in as if it were a single tree.
· Leave the leaves. Thanks to all the lignins and tannins, oak litter decomposes more slowly than most tree leaves, prompting many of us to shred or burn to get rid of all the “clutter.” But why do this, when millions of critters rely on oak litter for food and shelter, including fungi, bacteria, and mycorrhizae? Furthermore, oak-leaf litter can impede the spread of Japanese stiltgrass (Microstegium vimineum) and deter soil-eroding Asian jumping worms. “What are Asian jumping worms,” you say? Check out the Resources at the end.
· Why all the acorns all of a sudden? Oaks experiences boom and bust years when it comes to acorn production. This is called masting. Nobody has quite nailed down the reason why, although there are many theories from insurance against predator demands to improving pollen efficiency. An oak can produce three million acorns in its lifetime. As Doug Tallamy puts it, “Acorns are easy, free and plentiful, and they will grow into healthier trees than if you transplant established trees.” The primary point here is, go out and plant some acorns if you want oak trees. Or let the blue jays do it. We probably have these blue and white pioneering and absent-minded nursery enthusiasts to thank for more mature oak trees than any other natural source. One jay may gather up to 4,500 acorns each fall. Blue jays have even evolved a small hook at the tip of their bill for ripping open acorn husks and a gular pouch for holding up to five acorns (each one buried in a different spot, which they usually forget about). Refer to a subsequent section for more details on how to grow an oak tree from an acorn.
Identifying a White Oak Tree
Let’s start with some overall pointers when identifying a tree. Successful identification begins with knowing what to look for: What are the distinguishing characteristics? How do I distinguish it from similar species? Where does it occur, both in terms of range and habitat? Regarding the first question, most look at the leaves, but leaves are not always the most distinguishing characteristic, and they can vary considerably. Plus, they aren’t always there. Be sure to include other characteristics, like bark and acorns. For smaller trees, evaluating the twigs, buds, especially the terminal bud, leaf scars, and other characteristics will also help to distinguish between species.
Oaks (Family Fagaceae) are a very complex and diverse group that are primarily divided into two main groups: white oaks and red oaks. White oaks (other common species include swamp white oak, chestnut oak, burr oak) have a tendency to have rounded leaf lobes, whitish-gray bark, and acorns that mature in one growing season. Red oaks have bristle-tipped leaf lobes, bark is usually dark with different patterns of vertical plates and ridges, and acorns mature in two growing seasons. Members of the white oak group can be distinguished by the shapes of the leaves (e.g., deep vs shallow divisions between lobes, etc.) and acorns, not to mention habitat (e.g., swamp white oak likes it wet, white oak likes it dry).
White Oak (Quercus alba) Distinguishing Characteristics:
· Bark—Oak trees have thick, rugged bark. White oak bark is whitish, light gray with small, vertical blocky plates to long plates and narrow fissures. The bark usually consists of vertical cracks and ridges near the bottom of the tree and gets flakier toward the top. White oak twigs are smooth, whereas swamp white oak may have some furrows on the twigs and burr oak twigs would have corky ridges.
· Leaves—alternate; highly variable in size and shape but all lobes are rounded, somewhat narrow and more deeply incised than other oak species.
· Buds—short, somewhat rounded (not as conical as red oak buds); terminal buds are clustered at end of twig (characteristic of all oaks).
· Acorns—smaller cap (doesn’t cover entire seed) and top of cap has warty protrusions or knoblike scales (burr oak is similar but has a fringe), which differs from the red oak group acorn caps.
· Form—trees grown in the open have a wide, rounded crown.
Threats:
Oaks are the most widespread hardwoods in the Northern Hemisphere, but their populations are suffering. Lack of forest management, fire suppression, deer overabundance, and invasive plants are all threats that significantly inhibit oak regeneration. Climate change, invasive insects and diseases are additional challenges negatively impacting populations. Given the time it takes for an oak to grow, our window of time to proactively address these issues is closing rapidly. According to a 2021 White Oak Initiative report, without active forest management today, the American white oak population could face significant declines within the next 20 to 30 years and more extreme declines over the next several decades. Management activities using fire and herbicides to re
move undesirable trees and vegetation, shelterwood harvests, and deer reduction can help improve oak establishment and advance regenerating oak seedlings to the sapling or pole-wood stage.
Two important oak diseases to watch out for are oak wilt and sudden oak death. The latter started on the west coast and was confirmed in Pennsylvania in 2004, when a bonsai camellia was shipped into southeast PA. Refer to the Resources section for more information about these threats.
Planning & Planting
Planning
Now is the perfect time to plan your oak oasis. First, determine your site conditions and space. If you have room for a grove of trees, rather than a specimen or two, this would be ideal. How many trees can you fit in your space with an approximate 10-ft radius around each tree? Or simply plan out some 10x10 ft rows. If space is limited, consider planting a dwarf chinquapin oak (Quercus prinoides). Next, consider adding some lower canopy trees for structural diversity. Flowering dogwoods (Cornus florida) and serviceberries (Amelanchier canadensis) are often found growing near oak trees and make a beautiful counterpart, especially in the spring. Be careful with flowering dogwoods, as they can be easily stressed and susceptible to fungal infections under subpar conditions or when planted close to a kousa dogwood. Kousa dogwoods can easily spread dogwood anthracnose to flowering dogwoods, which shows no symptoms in the former but is often lethal to the latter.
Regarding site conditions, what type of soil do you have? Acidic, alkaline? Is it wet, dry, in between? Practically all oaks will do well in rich, well-drained soil. Choose pin oaks or swamp white oaks for wet places, and white oaks, chestnut oaks, or scarlet oaks for dry, thin soils. If you have dry soils and limited space, consider growing dwarf scrub oaks, which are more shrublike. An interesting tidbit of note, physiological studies of oak adaptation to climate and habitat reveal that distantly-related oaks (i.e. white vs. red) often coexist in the same habitats, while closely-related oaks (e.g., white oak vs. pin oak) tend to separate along gradients of altitude and moisture (Hipp et al. 2020). This is good news with regard to climate change, as oaks that are not predicted to do well may potentially be replaced by species with better adaptations.
Planting a White Oak Tree from an Acorn
White oaks are an excellent oak species to start from acorns. Their ability to germinate in the same year they are pollinated makes it easier to select viable acorns. Some even germinate before they fall from the tree! Plus, they are less likely to be collected by gray squirrels that preferentially select the red oak acorns, which last longer. With patience and time, planting an acorn can produce a stronger, healthier tree than transplanting. Oak trees spend the first year of their lives building the root system, a root system that can eventually extend as far as 60 feet deep and 120 feet wide. When we consider how each root helps the tree compete for water, sunlight, and nutrients, withstand droughts, and fight off pathogens and disease, it’s easy to see how transplanted trees that are root pruned or pot bound are severely handicapped when compared to trees with undisturbed root systems. Another feather in the acorn’s cap is that, when locally sourced, the acorn will be providing all the genetic material needed for evolutionary success in that particular location, as opposed to buying a tree sourced from far away and transplanting it.
Step 1: Gather the acorns. Look for acorns free of holes (collecting them before they fall to the ground may help you avoid this). Place them in a bowl of water and discard any that float. If you find acorns that are already sprouted, you can skip that last step. Obviously, they are viable.
Step 2: Plant the acorns. Since white oak acorns germinate in the fall just days after falling to the ground, you can plant them right away, about a half-inch deep. While planting them in the ground where you want the tree to grow would be ideal, it will also most likely result in a squirrel or chipmunk digging them up. Starting them off in flower pot (2.5 x 3.5 pots are ideal) with soil and potting mix is a good solution but requires a good place to put it overwinter where it’s protected from mice, freezing, and desiccation but cold enough for stratification. I use my unheated sunroom for this purpose. The trick for me is to remember to go out there and The tricky part is remembering to water it once a month. If you don’t have a cold place, you can also place the acorns in a plastic bagd with some damp peat moss or sawdust, seal it, and store it in the refrigerator for 2-3 months for cold stratification before planting.
Step 3: Plant the seedling. During the winter, it may seem like nothing is happening but in fact the acorn will be busy developing its taproot. In the spring, after the seedling has popped out of the soil and fully developed its first set of leaves (note that these are the only leaves the tree will grow during the first year, as it will be busy working on its root system), you can transplant it into the ground. Make sure the hole is deep enough but not so deep to cover the crown. Hold onto the tree as you fill the hole, pulling up on it gently and packing it tight. This will reduce the amount of settling over time and help prevent burying the crown (the place where the first roots come out). Be sure to water well in the first few days and monitor regularly in the first year. Although many oaks are well adapted to dry conditions, seedlings need extra care.
Step 4: Protect the seedling. Deer love oaks, especially tender seedlings. And they’re not the only ones. You can start small, but eventually, you will need a 5-ft high tube or cage. I prefer wire cages, but the standard green tree tubes work well, too, and are even preferred by some experts.
ICONIC OAKS IN CLEARWATER’S NECK OF THE WOODS
The Grandmother Oak—Kettle Run Farm
This majestic oak can be found at Kettle Run Farm. In 2007, Kat Alden and Bill Torretti (above right) permanently conserved the farm, along with a Centre County Natural Heritage Site supporting lupine (Lupinus perennis), the larval host to the globally rareFrosted Elfin Butterfly (Callophrys irus)
Heritage Oak—Oak Manor Farm
The Mierley family conserved their 300-acre farm near Standing Stone Creek in 2017, along with this heritage oak tree for which the farm was named in the 1930s.
Hemlock Haven Oak—Eagle Field
In 2007, Karl Striedieck conserved his 190-acre property, located on Bald Eagle Ridge, a prominent flyway for migrating raptors. A world-class glider pilot and conservationist, Karl houses gliders, a fire tower, raptors, and a host of other wildlife on the property.
When this 230-yr-old oak tree fell along the drive, Karl commemorated its life with this sign.
The above piece is from the oak. Note the tight tree rings, indicative of the site conditions at Hemlock Haven where the tree grew. Size is not always a sign of old age.
Winter/Spring Tips
Invasive Control
Winter is an excellent time for spotting the orange-red berries of oriental bittersweet. If you haven’t yet, get out there and snip the vines. Some of us may need a hacksaw for those really big ones! Freeing up the vegetation from the aerial stems is often the first step in controlling this very aggressive vine that’s capable of toppling large, mature trees. If you are able, bag up the berries and aerial growth in sealed trash bags for disposal. Take some spray paint with you and paint the vine “stump” to help you find and treat the regrowth later. One root system can support many small stems, making immediate treatment of the cut stem impractical. Forcing the roots and stems to send up new shoots and treating this regrowth with foliar-applied herbicides is usually more effective. Try to do this after July 1st to enhance transport to the root system.
Spring Cleanup
Focus on Not cleaning up your yard, as it can wipe out an entire generation of native pollinators. We’re not talking about honey bees, but native bees, nearly 4,000 species of which 90% are solitary nesters in ground, wood, or hollow plant stems. Those dead perennial stems, leaf litter piles, seed heads, scattered wood and leaves that look so unsightly may be housing mason bee cocoons, leafcutter bee nests, native wasp larvae, and beneficial predators that can help protect your summer veggies. This doesn’t mean you have to completely embrace a messy yard. Waiting until May when temperatures are consistently above 50°F, bundling and storing cut stems, and creating “pollinator corners” can go a long way in helping native bee populations thrive.
Selecting Native Plants
When you’ve figured out what you want to plant, here are some tips on what to do when you find a native plant supplier and how to shop for them, because not all nursery plants, or nurseries for that matter, are created equal:
· Take a guide with you when you visit a nursery. If you see a plant that you like, check to see if it’s included in your guide for your region. There is still a large range of variation in what many nurseries and other suppliers label “native.” It may be referring to a species that is native to the United States, but not to Pennsylvania or the mid-Atlantic region.
· Purchase plants grown locally from seed whenever possible, and make sure they were responsibly sourced. Native plants grown from cuttings or divisions do not have the same genetic diversity as seed-grown native plants. Cuttings are a good option, however, when looking for larger, woody plants. Just remember they will only carry less genetic diversity.
· Select “true” native species and avoid cultivars for the greatest ecological benefit. Cultivars have been genetically tinkered with to enhance certain characteristics desired by humans rather than wildlife, such as flower color. The label will show the scientific name (Latin genus and species) plus the cultivar name as a third word in single quotation marks (e.g., Rudbeckia fulgida ‘Goldsurm’). This is not to say that you should never choose a cultivar. There may be instances where a true native will not work, and cultivars offer a better solution. Or you may just prefer the cultivar. Weigh the options and decide for yourself if they outweigh the ecological benefits.
Resources:
· The White Oak Initiative (https://www.whiteoakinitiative.org)
· The White Oak Resilience Act of 2025 (https://www.congress.gov/congressional-report/118th-congress/house-report/910)
· Hipp, A., Manos, P., and Cavender-Bares, J. 2020. Ascent of the Oaks: How they evolved to rule the forests of the Northern Hemisphere. Scientific American. (How Oak Trees Evolved to Rule the Forests of the Northern Hemisphere | Scientific American)
· Tallamy, D. W. 2021. The Nature of Oaks: The Rich Ecology of Our Most Essential Native Trees. Timber Press, Inc.
· Oak diseases
o stelprdb5347329.pdf (Oak Wilt)
· Oriental bittersweet (Oriental Bittersweet)
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