Tag Archives: Parkwood

Environmental Education, Landuse Changes

English Ivy: Coming to a woods near you

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This is an article I wrote for the January issue of the Parkwood Inside/Out, serving the Parkwood community, next to Northeast Creek in southern Durham.

English Ivy: Coming to a woods near you

Now that Parkwood’s green areas are bare, the full extent of the English ivy problem is plain to see. In places behind Newhall, Euclid, Revere, and between Highway 54 and Euclid ivy thickly covers the ground, smothering native vegetation, including the next generation of canopy trees, creating what might best be called “ivy deserts.” A few native and non-native plants do sprout through the ivy, including poison ivy, but the spring beauties, trout lilies, bluets, pink wood sorrel, pussytoes, and other flowers and forbs that should gild the forest floor are excluded. Ivy might affect invertebrates living in streams flowing through an ivy-filled woodland and change the soil, because ivy has nitrogen-rich leaves, a vital plant nutrient. It can carry bacterial leaf scorch, which infects trees such as maples, elms, and oaks. Ivy vines thickly festoon trees, which might make them more likely to fall, though there is some controversy, and less able to get to sunlight.

Once in the canopy, ivy gets enough sun to flower and produce clusters of black fruits, which birds spread into new areas. In my yard there is some ivy kept under control in pots, but in the last 10 years a lot of ivy has crept in through seeding. Without pests or diseases, cold weather is probably the main factor limiting ivy here, by preventing fruit production and temporarily stopping photosynthesis, an advantage evergreen ivy has over deciduous plants. For this reason, ivy is not a major problem further north, but it is rampant in the Pacific Northwest.

As its name suggests, common or English ivy (Hedera helix) is native to the continent of Europe, as well as the Middle East and north Africa, but it was introduced here starting in the 18th century. In its native range it is kept in check and is a valuable food source for birds, some of the species that have become problematic introductions here, such as European starlings and house sparrows.

English ivy is in the same family as ginseng, so it is not a relative of poison ivy or Virginia creeper (in the cashew and grape families, respectively), but I thought it was related when I took a large cut stem and pressed it to my wrist to see what would happen, and my skin blistered, but less intensely than it would with poison ivy. I’m pretty sure it was an ivy stem, and not Virginia creeper, and some people do react to ivy, but from a different toxin than that in poison ivy.

Ivy has evergreen, palm-shaped leaves with three to five points in shade, but they become more lance-shaped in the sunny treetops. The vines appear hairy because of glue-producing roots, while vines high in the treetops lack roots. Stems can be almost a foot wide, and reportedly a 433 year old vine in Europe was more than 20” across. Ivy has tiny and inconspicuous yellowish flowers that appeal to insects with a short proboscis, such as flies, wasps, and moths. The resulting fruit, technically called a drupe, contains a few hard seeds and a toxic glycoside that sickens humans and can make birds vomit. Still, the fruits are nutritious and fatty, and are often eaten by robins, mockingbirds, and cedar waxwings. As with some other non-native plants, human disturbances, such as new roads, give ivy inroads into new areas. There is a lot of ivy in Parkwood now, but it is rare or nonexistent in intact woods nearby. Livestock and deer can apparently eat the leaves, but don’t appear to be making much of a dent in the problem. Non-native rats might be the main animal that can use an ivy desert.

Other than landscaping, people have used ivy for its antifungal and antibacterial properties and in dyeing, tanning, and varnish resin.

Controlling English ivy and other non-native plants is a good New Year’s resolution. Many non-natives can be grown without causing too much trouble for native vegetation and the neighbors. There are more controllable non-natives, such as the groundcovers Vinca minor and Vinca major (they are similar, but V. major is larger and possibly more difficult to keep in check), which only spread vegetatively, but they spread a lot in shade. There are also many native alternatives. Crossvine is an evergreen vine with showy spring flowers that attract hummingbirds. Yellow jessamine is also evergreen and showy. Virginia creeper is a pretty deciduous vine with red fall foliage and dark blue berries. There are several evergreen groundcovers, such as doghobble, Galax, and partridgeberries (common in Parkwood).

Environmental Education, Event Notices

Strange winter waterfowl

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We are meeting Sunday, February 16th at 4pm to plan for Creek Week, and our regular meeting will be February 23rd, at 4pm in the same place.

Below is another article I originally wrote for the Parkwood Inside/Out.

Strange winter waterfowl

Many unusual water birds winter in North Carolina. My favorite place to look for them is Crabtree Lake in [Cary], which is large enough to attract many birds, but also small enough to find them and easily accessible. It can be hard to see migrants, because they are wary and often stay far from shore but they usually swim from danger rather than flying. Parkwood Lake is also a convenient place to look, and even small ponds attract migrants, in addition to the Canada geese and mallard ducks that live here all year. It is not very easy to see the waterfowl staying at the Jordan and Falls reservoirs.

Geese and mallards aren’t supposed to breed here, but captive birds that didn’t learn to migrate were released, creating resident populations. Migratory geese swell the local population in winter, and in the mid-90’s there were many migrants with neck tags in Parkwood, making it easy to get to know geese as individuals.

The first unusual migrants I saw were small black ducks in a tight flock in the water at Clermont one cloudy winter day years ago. They were black scoters; the males being jet black with bright orange bills and the females paler with dark bills. We are used to puddle or dabbling ducks like mallards paddling around, eating plant matter from the surface or as deep as their necks will reach, but many migrants, such as scoters are diving ducks, and swim underwater. Scoters dive for foods such as mussels and barnacles.

Other diving ducks I have seen outside of Parkwood. At a nearby beaver pond about the size of the Lotus Pond I saw what I thought was a long-tailed duck, but it took off fast when it saw me, and long-tails are one of the fastest flying ducks. Long-tailed ducks, or oldsquaws in older guides, are white with black wings and black and gray patches. Like penguins, they swim with their wings, and venture to great depths, after molluscs, crustaceans, and fish. Last winter I frequently saw buffleheads at a wastewater treatment lagoon at Falls Lake. Buffleheads are the smallest duck in the US, and have big heads and striking black and white plumage. They were with wood ducks, and both species nest in tree holes, unlike mallards. Wood ducks are here year-round, and winter is a good time to search for these very wary and colorful ducks, but they prefer creeks and swamps. Buffleheads resemble hooded mergansers, one of three mergansers that winter and sometimes breed in NC. These unducklike ducks have rakish crests and pointed bills they use to catch fish underwater. I’ve seen them at Crabtree, but they are uncommon and wary. A week ago I noticed that there were four ducks, as well as a large flock of geese, at the large stormwater retention pond across Renaissance Parkway from Southpoint Mall. I didn’t have binoculars, but one of the ducks had a white patch, so there could be a pair of hooded mergansers there right now.

The most abundant winter visitor in the Triangle is the double-crested cormorant, which is not a duck. A few usually visit Parkwood Lake. Cormorants are dark and sit low in the water, with their orange bills up. They eat fish and, to make diving easier, their feathers are not very waterproof, so they periodically get out and hold their wings open to dry. There are flocks at the large reservoirs and they can be seen flying just above the water in ragged lines.

Handfuls of pied-billed grebes can be seen on most lakes. They are small ducklike birds with nondescript grayish fuzzy feathers and a dark bar on their bills. They also breed in NC and readily dive for prey such as crayfish.

American coots are pretty common. Coots are rails, chickenlike waterbirds, and are black and gray with stark white bills. They nod their heads as they swim in tight groups, and when they come on to the land at Clermont to eat vegetation and seeds. Coots sometimes breed in NC and are a prey of bald eagles, which have been seen at the Lake.

Vast flocks of pure white tundra swans and snow geese winter on the coast. One icy morning I saw a V of white birds in the cold blue sky far above Fayetteville Road, and they might have been swans or geese.

Now is the time to look, because the migrants will probably be all but gone by mid to late February.

Environmental Education, Event Notices

The life and death of an ash tree

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Our next meeting will be Sunday, January 26th at 4pm, to plan for Creek Week 2014 (March 15-22) and discuss some development issues, etc. Contact us for the address of the residence where we are meeting.

Below is an expanded version of an article I wrote for the January issue of the Parkwood Inside/Out. This giant ash tree grows beside the stream that flows from the corner of Barbee and 54, through Parkwood to NE Creek at the bridge on Grandale Road.

The life and death of an ash tree

An ash tree in Parkwood is one the largest I have come across. There are taller trees, but this ash is nearly four feet across, beating large ash in the wild bottomlands around NE Creek and the big ash in downtown Chapel Hill. Parkwood’s ash is a little south of McCormick Road, near the intersection with Auburndale, beside the stream in the common green area, and can be seen from the road. Ash trees usually have very straight trunks, but this giant leans southwest and has lost huge limbs to the force of wind or ice over its long life. It is hard to say why it leans. That section of woods is relatively young and this ash is the biggest tree there. It has pale bark, and as a reaction to tilting, it grows more on the leaning side, producing unusually deep 4” furrows, resembling a baleen whale’s throat or treads. In one place the bark is brown, probably from deer rubbing the velvet off their antlers. There are rows of holes created by yellow-bellied sapsuckers, woodpeckers that winter here and tap trees for sap.

During the growing season, the ash’s massive trunk is obscured by understory oaks, dogwoods, and black cherries. American beech, increasingly common in Parkwood, and Northern red oak saplings wait for the ash to fall. This is the only spot I know of where pawpaws grow inside Parkwood, though they are quite common as small riparian trees along NE Creek. The pawpaws probably would benefit from more light, though the site might still be a bit dry for them to produce their sweet bananalike fruit. There is a seemingly innocent sprig of English ivy, a plant which is taking over in nearby sections of the woods, and a Nandina bush with purple foliage, another non-native, but much less invasive. Partridgeberry, ‘wild onions,’ and grape ferns form the herb layer under the ash.

Each ash produces only male or female flowers, and this must be a male tree. Perhaps it is a parent of large ash on nearby Timmons Drive, or even throughout the area.

Our ash is probably a white ash. Green, pumpkin, and Carolina ash also grow in Durham. They look similar, all living up to their scientific name, Fraxinus, the Latin name for ash, which also means spear, and describes their typical soaring shape. Ash have leaves and twigs growing in pairs along a stem, and their pinnately compound leaves are made up of oval leaflets, resembling the leaves of walnuts, hickories, and locusts. In fall ash turn gold, orange, and purple. Ash saplings have smooth gray bark and mature trees have somewhat furrowed or rough bark, depending on the species.

White ash is the most economically valuable ash. High-quality baseball bats are made from white ash, as well as other objects requiring lightweight, strong wood with a spring, like oars, lacrosse sticks, musical instruments, furniture, and bowling lanes. It is also an easy to split, hot burning firewood. White ash has been used to relieve fevers, sores, and snake bites, as a laxative, and as an aphrodisiac, among other medicinal uses. Ash have a long history in mythology, for example the Norse axis mundi/world tree Yggdrasil is supposed to have been an ash, and according to folklore snakes don’t like ash trees. White ash likes well-drained, but not very dry soil and is one of the first trees to sprout in abandoned fields. White and green ash can tolerate shade as seedlings, waiting for their chance to shoot into the canopy when an old tree dies. The big snowstorm that left two feet of snow and ice and other bouts of freezing rain have knocked down most of the young pines behind the Parkwood Volunteer Fire Station, leaving a woods of only ash and winged elm in places. Pumpkin and Carolina ash like wet habitats, and ash are one of the main trees in swamps and bottomlands. Ash trees can be seen next to the Parkwood Association office, where there used to be a trailer, and at the Parkwood Convenience Store, at the corner of Seaton and Revere. Ash of some kind can be found on most streets in Parkwood and are common throughout the Triangle.

Late last summer I watched big pale green, red, and yellow hornworms on an ash sapling at Falls Lake. These were waved sphinx moth caterpillars, but the red markings were unusual. Usually their larvae don’t have any red coloration, but these were mostly red with yellow markings when small and then mostly green, but with red heads, horns, and markings. A few other sphinxes feed on ash, as do caterpillars of black and yellow Eastern tiger swallowtails. These green caterpillars have fake eyes complete with angry eyebrows, to mimic snakes, and if that fails, they can send out bright orange ‘horns’ that emit a smelly fluid. The big, shiny black rhinoceros or unicorn beetles sometimes found under streetlights at the Parkwood Shopping Center also eat ash. Ash have wind-pollinated flowers in early spring, but honeybees and other insects sometimes harvest pollen from male flowers. The winged seeds, or keys, of ash trees are eaten by weevils, mice, and birds such as wood ducks, turkeys, and purple finches. Large ash often have hollows where birds and squirrels can nest. Our ash seems to house a colony of big black ants, judging from the seemingly arboreal ants walking along its trunk last summer. Deer and rabbits eat the leaves while beavers like ash bark. Ash growing around the beaver impoundments on Grandale or elsewhere could host mistletoe.

Native beetles and two species of dayflying moth that mimic wasps bore into living or dead ash trees, but a new ash-boring beetle from East Asia is on its way to killing virtually all ash. Emerald ash borer or EAB reached Michigan in the 90’s, probably in shipping materials. It wasn’t noticed until 2002 and has since spread throughout the Eastern US and Canada, in part because people violated quarantines on firewood and other products. Their grubs tunnel under the bark of trees as small as 1” across, and since these are non-native animals, they come in out of control numbers that girdle our naïve ash, killing them within a few years of colonization. A good online resource to check out is www.emeraldashborer.info .

Earlier this summer emerald ash borers crossed into Granville County from a pocket across the border in Virginia and a quarantine was imposed (see http://www.ncforestservice.gov/forest_health/fh_eabfaq.htm ). This is likely to be the end for Parkwood’s great ash in the near future, when the emerald ash borer gets to Durham, on its own power or by hitching a ride, and a great many beetles could come from it. There is cause for hope – some ash seem to have survived the borer up north, introduced Asian and native parasitoid wasps could help control the beetle, and individual trees can be protected with insecticides that are relatively safe for the environment. Emerald ash borer has a big ecological and economic impact, and even harms human health, so communities in the Triangle should prepare.

You can read more about emerald ash borer in my article in the February issue of Carolina Gardener magazine (www.carolinagardener.com).

Environmental Education

Watch out for blooming catalpas this month

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This month there will be many showy white flowers on the small catalpa in front of the condos on Revere Road in the Parkwood subdivision in southern Durham. There are actually two very similar species, Catalpa bignonioides, the Southern catalpa, and C. speciosa, the Northern or hardy catalpa. Southern catalpas grow naturally in the Deep South while Northern Catalpas grow in the region where the Ohio joins the Mississippi. The Revere Road tree is probably a Southern catalpa. The species difference is dramatically revealed in spring, when they bloom at different times, but there are some other differences. Southern catalpa flowers have more spots and fewer blossoms per cluster. They also don’t grow as tall as Northern catalpas and there are differences in the seed pods and bark patterns. Apparently the crushed leaves of Southern catalpas have a bad smell. Northern catalpas might be the only ones that have glands at the base of the leaves, perhaps to attract ants for defense. Catalpas resemble royal paulownia, Chinese natives with big leaves and clusters of pale blue flowers in March or April, and have round seed pods. Catalpas are related to native crossvine and trumpet creeper. The word catalpa is supposed to be a native term for this tree while bignonioides refers to a vine with similar flowers and speciosa means ornamental.

Catalpas self-seed here, but are still pretty rare. The only other specimens I can think of are a few at Sedwick and Prospectus Drive, one on Grandale, one growing beside Northeast Creek near Jordan Lake, and several individuals of both species in Chapel Hill and Carrboro. There is a towering Northern catalpa across South Road from Coker Hall at UNC. A week ago it was crowned with white blooms and is probably peaking or past peak by now. There were one or two large catalpas near the corner of Fayetteville and 54, by Crooked Creek. Catalpas stick out because of their peculiar yellowish green leaves and pagodalike canopy. In their native habitat, catalpas grow near waterways and in bottomlands. They seem to prefer full sun, which could be a reason they aren’t more abundant here.

Catalpas were probably planted so widely for their flowers, and sometimes to grow caterpillars for fishing bait. Catalpa wood is sometimes used indoors, but is mainly used for posts, railroad ties, and telephone poles, because it is rot-resistant though brittle. Bark tea has been used as an antiseptic, laxative, sedative, and to treat snake bites and worms, while the pods were also thought to be sedative and to have an effect on the heart. The leaves were used to treat flesh wounds, as was seed tea, which was also used for respiratory problems. Catalpas are also sometimes called Indian cigars, which could be because kids smoked the pods

The flowers are grouped in panicles on the ends of new shoots. When they open, the large frilly white flowers are tubular and have five asymmetrical petals. They have dark purple spots and two yellow lines inside to guide pollinators. Bumblebees, honey bees, moths, butterflies, and ants are among the insects attracted by the nectar and pollen, yet one source says the nectar is toxic to skipper butterflies and ants. Catalpas will probably bloom for a few weeks, and then the trees sprout long, thin green pods all summer.

Catalpas are noticeable again in summer when they attract catalpa sphinx moths. Apparently their only larval food is catalpa, and the adults don’t eat. Like other sphinxes, catalpa sphinx caterpillars are hornworms, with a ‘horn’ on the tail, and they have striking yellow, black, and white stripes from head to tail. They are unusual for hornworms in being social during most of their caterpillar stage, and groups sometimes defoliate even a tree the size of the one in Parkwood. If Wikipedia is to be believed, cropdusting was first used against catalpa worms. When irritated they vomit a green liquid and thrash.

Nothing else seems to eat catalpa leaves much, so the trees are quiet until the brown pods attract angular gray leaf-footed bugs in late fall. As the weather gets cool, the pods split in half lengthwise, releasing winged seeds, while the husks remain on the trees into winter.