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From Shoots to Stands

Bamboo serves diverse purposes at the Zoo and around the world.

by Susan Lumpkin

No bouncing baby anymore, three-year-old giant panda Tai Shan is now tipping the scales at a near-adult weight of about 185 pounds. With this comes a grown-up panda’s hearty appetite for bamboo, which is essentially all any giant panda eats. This presents a giant-sized challenge for the Smithsonian National Zoo’s staff who must keep up with the demand for ever more of the stuff.

In fact, the Zoo’s head of nutrition, Mike Maslanka, says harvesting bamboo is arguably the hardest job at the Zoo. If you have ever taken a whack at controlling bamboo in your own backyard, this may come as no surprise. The woody stems, or culms, don’t yield easily to clippers.

Maslanka and his team are responsible for cutting all the bamboo that keepers feed to the Zoo’s three giant pandas—as many as 400 tough stalks per day in the winter when giant pandas and other animals chow down most ravenously. In addition to serving the giant pandas 100 to 300 pieces of bamboo—up to nearly 90 pounds’ worth per day—nutrition staff cater to red pandas. These bamboo-eaters each need a stalk a day. The Zoo’s Asian elephants and great apes, for which bamboo is primarily an enriching supplement to their diet, each account for another 60 or so stalks.

Red Panda
The Zoo's giant pandas, elephants, red pandas, and other animals munch through hundreds of bamboo stalks each day. (Ann Batdorf/NZP)

Most of the bamboo harvested for the animals is of two types: species of Phyllostachys, especially yellow groove bamboo (P. aureosulcata), and arrow bamboo (Pseudosasa japonica).

These and other bamboos grow abundantly on Zoo grounds. According to Zoo horticulturalist Preston Burke, nearly five of the Zoo’s 163 acres are planted with one species or another of the hardy, fast-growing grasses. Even so, there’s not enough to meet the demanding appetites of three giant pandas. Green year round, bamboo beautifies the park’s grounds. For this reason, bamboo is harvested from the Zoo’s gardens only in emergencies and for a few days in the spring to thin out dense stands. Instead, staff trek out to the Zoo’s Conservation and Research Center in Front Royal, Virginia, to a private property in Fort Washington, Maryland, and a few other local sites to cut their quota.

In all, the Zoo’s bamboo collection includes about 42 different varieties, from the diminutive dwarf bamboo (Pleioblastus pumilus), which forms a ground cover, to towering timber bamboos such as some Phyllostachys species. But the Zoo hosts only a small sample of the myriad bamboo species—fascinating plants that underpin many natural habitats.

Bamboo Diversity

Around the world, there are some nine or ten thousand species of grasses, of which as many as 15 percent are bamboos. Estimates of the number of bamboo species vary, but recent figures range from 1,200 to 1,500, with most of this number belonging to the woody bamboos. Only about 100 or so species don’t have woody stems, most of them confined to the Americas, including the smallest known bamboo. Standing less than an inch tall, Raddiella vanessiae was just discovered in French Guiana in 2007. In contrast, the tallest woody bamboos, such as the Asian Dendrocalamus giganteus, may exceed 120 feet. Woody bamboos in the widespread South American genus Guadua grow to nearly 100 feet.

Most people associate bamboo with Asia. Indeed, China is home to the greatest number and diversity of bamboos, with 626 described species. India boasts 102 species, followed by Japan with 84. In contrast, only five species of woody bamboo grow in Africa. About 33 grow in Madagascar, and all but one of these is found only on that biologically unique island. In the New World, there are about 430 species of woody bamboos, with the greatest number—more than 130—in Brazil.

Asian elephant
One of our Asian elephants enjoys bamboo at the Zoo. (Jessie Cohen/NZP)

Although the bamboos that grow in North American gardens, like those at the Zoo, are almost entirely species introduced from China and Japan, there are a few native North American bamboos. One, called giant cane (Arundinaria gigantea), grows at the Zoo near the Reptile Discovery Center. Giant cane, which may reach 23 feet tall, was once very common in the southeastern United States. There, it grew in huge expanses of dense stands, called canebrakes, as large as four miles long and a quarter-mile wide. Canebrakes offer shelter and food to a host of animals, from black bears and turkeys to rattlesnakes and butterflies, but they have vastly diminished in extent. Early European settlers to the United States fed livestock on the cane and sheltered their animals in the brakes, but they replaced most of the stands with crop fields. The presence of cane indicated that the soil beneath was fertile, and cane was easier to chop down than trees. Scientists speculate that the loss of canebrakes may have contributed to the decline (and probable extinction) of Bachman’s warblers. These birds may have foraged for insects among the leaves and stalks, and used the stands as nesting sites and shelter.

Switch cane (A. tecta) is much smaller, usually under six feet, and thrives in slightly different habitat. But, until recently, it was not deemed a separate species from the giant form. Like its bigger sister, switch cane also once grew in large thickets and served as food and shelter for wildlife.

Scientists are still discovering bamboo species in North America. A third U.S. species was identified just two years ago. Called the hill cane (A. appalachiana), it was found in the southern Appalachian Mountains, and, unlike the others, drops its leaves in the fall.

People might guess that the closest relatives of the North American bamboos are from South America. But they’re not; they’re actually Asian. Genetic studies suggest that arrow bamboo, native to Japan, may be giant canes’ next of kin, although they do not look very much alike. The arrow bamboo that giant pandas eat is the most abundant species at the Zoo.

Food for All

Only a few wild animals other than giant pandas consistently eat the leaves and stems of woody bamboos, which are low in nutritional value. The tough leaves and stems also require very strong teeth and jaws to crunch. Red pandas prefer tender new leaves, although they can crush tougher ones when necessary.

Shoots, however, find a place on the menus of many species. Shoots are the new growth of stalks that erupt from underground stems called rhizomes through which bamboo reproduces vegetatively. They are succulent, high-protein morsels, and abundant when they are in season. Giant pandas love them, as do takin, tufted deer, wild pigs, Asiatic black bears, and many other mammals that share the giant panda’s bamboo forest habitat in China.

Giant Panda

Bamboo is important to humans and wildlife. (Jessie Cohen/NZP)

Golden bamboo lemurs, a critically endangered primate of Madagascar, are year-round shoot specialists. They dine almost exclusively on the shoots of a giant bamboo found only on that Indian Ocean island—despite the fact that these shoots are naturally laced with cyanide. These cat-sized animals ingest enough cyanide in a day to kill 12 similarly sized primates, without any apparent ill effects. How they cope with the poison is unknown, but related species haven’t evolved the same capacity. The greater bamboo lemur eats only the pulp and culms of the giant bamboo, while the gentle bamboo lemur eats the shoots of a different bamboo species; both avoid the giant bamboo shoots.

Bamboo shoots are also seasonal favorites of eastern mountain gorillas in Africa. Large males gorge themselves on as many as 75 pounds of the tasty treats a day in the dry season, when the shoots form about 90 percent of their diet. These shoots are full of cyanide too, and the gorillas suffer from diarrhea during their shoot binges. Scientists suspect gorillas cope by eating a particular kind of soil with chemical properties similar to those of Kaopectate, which we humans use to treat diarrhea and upset stomachs.

People enjoy bamboo shoots as well. To get rid of the toxins, they boil the bamboo shoots in several changes of water. The majority of commercially available shoots come from just a few Asian species grown on plantations. A cultivated variety
of one of these, Phyllostachys edulis, thrives on the Zoo’s Asia Trail. Originally from China, this species is now grown for shoots as well as for construction material throughout Southeast Asia.

Although commercial harvesting doesn’t affect giant panda food sources, local harvesting can affect giant pandas. In the spring, people swarm into the pandas’ bamboo forests to collect bamboo shoots for personal consumption and local markets. The shoots are sometimes the same species that pandas eat, but even when they aren’t, the presence of so many people in the forest may disturb the sensitive bears.

The four species of Asian bamboo rats are also confirmed bamboo lovers. These burrowing rodents live mostly underground, tunneling through the soil and munching on the roots of bamboo. On the other side of the world, four South
American bamboo rats, known as coro-coro, also rodents but not closely related to the Asian varieties, live in tangled bamboo thickets and eat the plant’s leaves, stems, and shoots.

Many animals feast on bamboo seeds when they are available. And this brings us to the most enigmatic feature of bamboos. Most of these plants grow for a long time, spreading via the branching of their underground rhizomes and then, in one big burst, flower, set seeds, and die. What’s more, all members of a species, or all those in a particular area, do this in waves over several years. The intervals between flowering events vary from three to 100-plus years, most often 15 to 60 years, depending on the species. Japanese timber bamboo, Phyllostachys bambusoides, found at the Zoo on Asia Trail, is the champ in this regard, waiting 120 years for its first flowering bout.

Scientists don’t know what triggers mass flowering, or why bamboos have evolved this unique reproductive strategy. But some animals take advantage of the massive numbers of seeds that suddenly appear when an abundant species finally fruits. In Asia, rats of various species eat the seeds. After feasting, they reproduce prodigiously and plagues of rats end up invading human croplands and dwellings in search of food once the seeds are gone.

Zoo Bamboo
Bamboo at the Zoo. (Mehgan Murphy /NZP)

Many birds also eat bamboo seeds, and a few birds even specialize on them. Some South American species, including the critically endangered purple-winged ground-dove, follow the waves of seeding Guadua bamboo, moving nomadically in search of new patches, while the related maroon-chested ground-dove breeds in seeding Chusquea bamboo stands.

Many more birds, including insecteating species, make their homes in bamboo thickets that are abundant in food. According to Birdlife International, more than 15 Asian birds live almost exclusively in bamboo and many more use bamboo as a significant part of their habitat. Similarly, in Peru, scientists have found 19 birds that live primarily in Guada bamboo. The bamboo foliagegleaner not only lives in Guada thickets, it builds its nest inside the bamboo’s twoand- one-half-inch diameter stems, which are hollow between the joints.

Three species of tiny Asian bats also roost in the hollow sections of large bamboo species. The largest of these, the greater bamboo bat, is less than two inches long, followed by the lesser bamboo bat, at about 1.5 inches, and the smaller still pygmy bamboo bat, which was discovered in China in 2007. All these bats have flattened skulls that enable them to slip into the bamboo stems through narrow slits created by beetles. As many as two dozen lesser bamboo bats may roost in a single hollow section averaging about ten inches long and nine inches in diameter.

Building With Bamboo

As important as bamboo is to a diverse array of wildlife, it is immensely important to people too. Some 1,500 different uses of bamboo have been recorded, including food, fuel, medicine, clothing, paper, musical instruments, tools, baskets, and building material. Today, bamboo is touted as a sustainable alternative to timber, and the cultivation of bamboo is promoted by groups such as the International Network for Bamboo and Rattan (INBAR) as a way to alleviate poverty among poor rural people in Asia, Africa, and South America. According to INBAR, “Virtually every product which is now produced from wood can be effectively produced from bamboo,” and more sustainably, too, thanks to the swift growth of many species. Phyllostachys bambusoides reportedly grows 47.6 inches in a single day. Growth rates of a foot or more a day are common, and culms reach 60 to 80 feet in one growing season.

The fast and seemingly never-ending replacement of harvested bamboo stalks means that Zoo browse-cutters are never out of work—and the Zoo’s bamboo-loving animals are never out of food.

—Susan Lumpkin is a freelance writer and avid gardener who is working on a book about rabbits.

More: "Bamboo to the Rescue"