Create Urban Forest Diversity

Black cherry hosts tiger swallowtail caterpillars and many other species of butterflies and moths. Photo by Michael Singer.

Tallahassee is fortunate to currently have a considerable urban forest, though it is constantly being whittled away through development, storms, and fear of storm-related damage to homes. The average tree canopy is rated at 55% of land. This average puts Tallahassee close to number one in the nation for urban forest coverage. One problem with our forest is the lack of diversity in the species make-up. According to the City’s Urban Forest Master Plan three native trees (Carolina laurel cherry, water oak, and laurel oak) and one highly invasive non-native tree (Chinese camphor) are short lived, weak wood species that make up a full 38% of the forest. The long-lived sturdy live oak makes up 7% of the forest.

Loblolly pines and live oaks dominate the canopy in Walthall’s backyard. Photo by Donna Legare.

The diversity of tree species has an impact on the overall health of the forest, its wind resistance, and the food value for wildlife, from invertebrates to mammals. In terms of wind resistance, the four species making up this 38% are all considered to have very low wind resistance. If you are concerned about tree damage during a storm, choose smaller trees such as holly, greybeard, flatwoods plum, redbud, and red buckeye. The most wind resistant large trees are Southern magnolia, live oak, sweetgum, cabbage palm, pecan, and red maple.

For wildlife food, always turn first to American native species. Don’t put your entire focus on berries for birds. Berries are important seasonal sustenance for birds, especially during migration, but insects are the key to healthier food chains.

As an example, birds will eat the berries of Chinese camphor and spread seeds all around town, growing the percentage of Chinese camphor in our urban forest. Meanwhile, there are few insects that can find sustenance on this foreign tree. In contrast, native oak trees in our area can host 395 species of butterflies and moths in their larval form as caterpillars. A native red maple may host 171 species. These caterpillars are functionally soft bags of proteins for birds, lizards, frogs, and other wildlife.

White oak and fringe tree add fall color among the evergreen magnolias and pines in this yard. Photo by Vanessa Crisler.

Caterpillars are not the only insects in our native tree canopy. Thousands of species are on the leaves and branches, though we seldom see them. Many insects try to hide or use deception and stillness to survive the winter. Our resident and migrating birds search the treetops like a fine-tooth comb looking for this source of food, yet the insects are usually no threat to the tree or humans. Don’t fear the bugs! Search the National Wildlife Federation’s Native Plant Finder and enter your zip code; the site will show how many species of caterpillars use particular native plants in your area. This tool can help you select a tree for your yard.

A diverse native tree canopy is a major component of a healthy ecosystem that we need for human survival. What happens to us if we do not have trees supplying nectar, pollen, and leaf food to native pollinators? The flowers of trees such as red maple, black gum, black cherry, magnolia, tulip poplar, dogwood, redbud, Chickasaw plum, Southern crabapple, native hawthorns, and sassafras all supply nectar and pollen for bees along with hosting insects for many types of wildlife to eat.

If you have native trees in your yard, be sure to leave the leaves on the ground where they fall. Experts suggest leaving the leaves out to the dripline of the tree’s branches. Hundreds of species of insects live in the leaf litter. Some moth caterpillars eat no green leaves, consuming dead leaves on the ground exclusively. Many moths or butterfly caterpillars drop to the ground and hide in leaf litter to spend the winter in a cocoon or chrysalis. If lawn grass is beneath the tree, they usually die. Other insects merely hide through the winter, often becoming food for birds and other wildlife. Dead leaves are a critical part of a healthy ecosystem. I give you permission to be lazy – leave the leaves! If you prefer to have some open lawn in your yard, as I do, just rake the leaves into existing beds.

Silverbell in its spring glory among the urban forest at Native Nurseries. Photo by Jody Walthall.

As our city population grows, we clear cut and bulldoze hundreds of acres of stately trees for apartments, houses, parking lots, and roads. If you have open space for trees in your yard, you can help make up for this loss. There are too many beautiful and useful species of trees to mention. Some large trees to consider are winged elm, Southern red oak, white oak, Shumard oak, swamp chestnut oak, basswood, mockernut hickory, and bald cypress. Rather than the smaller non-native Drake elm or crape myrtle, choose blue beech, hophornbeam, silverbell, hoptree, Hercules club, American olive, or redbud. Choose a tree based on your soil and sunlight conditions.

Trees, especially live oak and pine, give Tallahassee a sense of place. They are so valuable for multiple reasons: preserving our mental health; cooling our streets, parking lots and homes; creating beauty; sequestering carbon; controlling erosion; naturally feeding wildlife.

Every yard matters and every tree counts. What you plant in your own yard makes a difference to the local food web. If you have room for more trees in your yard, winter is the best time to plant.

Black Gum Stakeout

I spent two hours communing with a black gum tree on Sunday morning.

Earlier in the week, I was biking the Munson Hills Trail with my wife and noticed a fruiting black gum on the edge of an ephemeral pond. I went back to see which birds were coming to it. I parked at the nearest trailhead, biked the short distance back out to the pond and got there at half past eight. I leaned my bike against a tree and started watching.

There are a lot of ephemeral ponds in the longleaf woods of the Munson Hills. Seasonally, they fill with rainwater and become important breeding areas for salamanders and tree frogs. Most of these ponds are roughly circular. This one was two hundred feet across and currently dry. In its center was a stand of buttonbush, which can handle inundation, surrounded by dog fennel. Then, a more open area of low grasses, meadow beauty and St. john’s-wort. At the edge of the pond there was a thin Goldilocks zone for upland plants, just high enough to be out of the water and just low enough to gain some fire protection. Along this edge grew a fairy ring of live oaks. Some were smaller, but one was old and large, around four feet in diameter.

The big oak was only about forty-feet tall, but very wide. Its first foot-thick horizontal limbs came out at head height and spread forty feet before touching the ground. Sheltered under its limbs was a thick growth of huckleberry, sparkleberry, and sapling oaks. Growing a few feet from the oak’s trunk was a black gum. It is likely that some bird that had been feeding in a distant gum tree had perched on an oak limb and deposited gum seeds with its droppings. The resulting gum tree had grown through the oak’s branches and was now sixty feet tall. Its lower branches intermingled with those of the oak, but most of its canopy jutted above it.

A black gum can live for hundreds of years. Its trunk was over a foot in diameter and it may have been growing there for a century. There are male and female gum trees and only the females bear fruit. Technically, gum fruits are drupes. A smaller version of a cherry, they have a single seed surrounded by fleshy pulp.

Black gum leaves begin to turn red when their dark fruits ripen in late September about the time of the autumnal equinox. The red leaves act as bird flags to attract feeding birds that distribute gum seeds in exchange for a meal of fruit pulp. It is a favored seasonal food for both resident and migrant birds.

I saw movement in the low shrubs beneath the oak and watched as a catbird branch-hopped up into the black gum and grabbed a fruit. A bright red summer tanager flew in and landed on an upper branch. It looked around and fluttered up to grab a drupe, using its own weight to pull it off. It landed on a branch for a moment with the fruit in its beak before swallowing it and looking for another. Among the gum’s branches I could see leaves jiggling as other birds fed. I found Northern Flicker and Red-bellied Woodpecker. The woodpeckers would hang in the branches and pull drupes off. A Northern Mockingbird landed on a branch, but was quickly chased off by a woodpecker, before it could feed.

Then, all the feeding birds flew off. During the time I watched, there were periods of inactivity punctuated by feeding forays from small flocks and individual birds. I saw movement in an upper branch as a Swainson’s Thrush fed. A small flock of bluebirds came in and chased each other through the canopy, stopping occasionally to grab a drupe. A pair of Blue Jays landed in the tree, but I did not see them go after the fruit.

Often, one of the low spreading oak branches would obscure my view. I started walking in a wide semicircle, changing position to get a better look at flitting birds. Usually, the best spot was the one that I had just been in and I ended up walking over a mile while making observations.

It was a pleasant and peaceful two hours to spend with a tree. In between bird sightings, I listened to the wind in the pines and watched the blue morning sky as Barn Swallows, Mourning Doves, a Chimney Swift, and a high-flying Red-headed Woodpecker passed overhead.

That black gum never actually spoke to me, but by watching it, I learned a lot about how it fits into the local ecosystem. In the end, I observed eight bird species feeding on the gum’s fruit; Red-bellied Woodpecker, Northern Flicker, White-eyed Vireo, Tufted Titmouse, Gray Catbird, Eastern Bluebird, Swainson’s Thrush, and Summer Tanager.

Not a bad way to spend a Sunday morning.

Endangered Wildflowers for Your North Florida Yard

The state of Florida is celebrated for its biodiversity, ranking sixth in the United States in total number of vascular plant species. Most of its rare plants are protected from human impact by federal law, specifically the 1973 Endangered Species Act (ESA), which currently protects 566 native plant species in Florida.

A species is declared “endangered” when it faces likely or imminent extinction. It is listed as “threatened” when extinction is likely if negative changes predicted to affect a large part of its range are not prevented. Of the 566 plant species currently listed for Florida, 448 are endangered and 118 are threatened. Fifty-four of these species are on the federal list of endangered plant species and 14 are on the federal list of threatened species. Florida also ranks among the top five states in endemic species, which are plants only found in our state and nowhere else in the world.

Conservation of these species’ hinges upon public education and awareness. Substantial efforts by federal, state, and local agencies have made Florida’s citizens better aware of the potential presence of these species, their rarity, and the need for their protection.

Endangered Wildflower Species

Monarch butterflies depend on wildflowers like Brickellia to fuel them during breeding and on their long migration. Photo by Elizabeth Georges.

Flyr’s Nemesis (Brickellia cordifolia)

Brickellia is well known for growing in full sun and sandy soil, however, I have started a patch in rich, moist woodland soil in a shady garden under a live oak, and it is flourishing. Late summer to early fall is when Brickellia blooms. This perennial wildflower can reach heights of three to four feet and produces disc flowers, not the typical ray flowers of other asters. At the end of each stem, it generates a large number of blooms in compact clusters. Each flower head has a wispy, spidery appearance due to its extraordinarily long styles. They are incredibly alluring to butterflies and range in color from nearly white to bright pink.

Although Brickellia is easy to grow and propagate, there is very little of it in the wild. There are some small, surviving populations in Wakulla, Jefferson, and Alachua counties and a few in Alabama and Georgia. It is on the state endangered list here in Florida and listed globally as a G2/G3 species (imperiled globally because of rarity or vulnerable to extinction throughout its range).

Columbine, with its nectar-filled red spurs, blooms just at the time that hummingbirds are returning from their winter sojourns in Central America and Mexico. Photo by Elizabeth Georges.

Marianna Columbine (Aquilegia canadensis var australis)

Columbine, with its nectar-filled red spurs, blooms just at the time that hummingbirds are returning from their winter sojourns in Central America and Mexico. Photo by Elizabeth Georges.

The only columbine endemic to Florida, this easily grown perennial wildflower is also an endangered subspecies. Although uncommon throughout the majority of the state, Marianna columbine is abundant in the Marianna region and can be seen at Florida Caverns State Park growing with trillium, bloodroot, and other spring ephemerals on limestone outcrops. It blooms in early spring, just in time for ravenous hummingbirds and butterflies that have just finished their migration.

Plant this rare wildflower in part sun to shade in rich, average to moist soils that have a high pH. To make the soil more alkaline and your columbines happy, you can add dolomite lime or place a limestone rock close to your plants. Foundations and certain walkways will also leech lime into the soil to increase pH.

Purple coneflowers are among the best native wildflowers to attract butterflies, native bees, and birds to our gardens. Photo by Donna Legare.

Purple Coneflower (Echinacea purpurea)

While the purple coneflower is quite rare in Florida, it is widespread in the eastern half of North America. It is recognized as a state endangered species in Florida because it is only found in a small number of limestone glades in Gadsden County.

It is a robust, drought-tolerant perennial that can grow in both full and partial sun. It is resilient and simple to grow – not at all picky – but it does prefer well-drained, neutral to alkaline soil. Therefore, adding a little dolomite lime to our acidic Tallahassee soil is a good idea, unless you’re planting it in garden soil that has been improved over time with mushroom compost.

This magnificent wildflower will bloom continuously from summer till frost, providing you (and the pollinators) with months of enjoyment. As a member of the Asteraceae family, what appears to be a single flower is actually a flower head made up of numerous smaller flowers. The head of purple coneflower is orange and shaped like a cone, encircled by pinkish-purple petals that stand on erect stalks reaching two to five feet tall.

In the butterfly garden, pipevine is the sole food for the pipevine swallowtail caterpillars. Photo by Elizabeth Georges.

Pipevine (Aristolochia tomentosa)

This native woody vine is a host plant for the pipevine swallowtail butterflies. It thrives in part shade to full sun and grows vigorously, reaching 20 to 30 feet.

Pipevine has large heart-shaped leaves and grows wonderfully on a trellis, arbor, or fence. It prefers medium moisture, well-drained soil, and does not like to dry out. Overall, it’s a tough perennial and will reseed readily in your butterfly garden.

Chipola coreopsis is a great groundcover for partial shade that pollinators love. Photo by Elizabeth Georges.

Chipola Coreopsis (Coreopsis integrifolia)

This coreopsis is quite rare in Florida, listed as a state endangered species and vouchered only in five counties, all along the Georgia border. It can be found in floodplain wetlands along blackwater streams, where it receives lots of moisture and dappled shade.

Florida is home to 15 species of coreopsis, and they can sometimes be a bit tricky to differentiate. Chipola coreopsis is an evergreen perennial that forms basal rosettes in spring that can spread in all directions by underground rhizomes. By late summer into fall, the stems eventually reach a mature height of two feet with multiple bright yellow bloom stalks. It is an attractive wildflower that also functions as a mat-like groundcover that can form stunning masses of color and contrast.

We invite you to learn more about endangered wildflowers by growing some of them in your own yard. Preserving these plants, whether in their natural setting or a more monitored environment, is very important and can be rewarding as you are taking part in real conservation at home. For some of these species, it could very well be their greatest chance for a future in our state.