Archive for the ‘Plants & Trees’ Category

Preventing Plant Invasions

Monday, June 28th, 2010

By Janet Marinelli
AS THE OLD saying goes, an ounce of prevention is worth a pound of cure. This is especially true of the struggle to control invasive species.

In the New York metropolitan area, where I live, roadsides have been overtaken by solid stands of purple loosestrife, and forest understories are thick with Japanese barberry.

Biologists consider invasive species such as these to be one of the two greatest threats to native plants and animals, second only to the outright loss of habitat to suburban sprawl, agriculture, and industrial development. Land managers fight a daily battle to remove invasives from important natural areas.

The conventional wisdom, at least in horticultural circles, used to be that most invasive plants were introduced accidentally—in agricultural seed stocks, say, or even on the bottom of some unsuspecting tourist’s shoes.

But during the course of researching Brooklyn Botanic Garden’s influential 1996 handbook Invasive Plants: Weeds of the Global Garden, my colleagues and I were dismayed to discover that about half of the worst invasive plants currently degrading natural habitats from coast to coast were brought here intentionally, for horticultural use.

While the vast majority of species planted on highway rights-of-way, in public landscapes, and in home gardens are not invasive, a small percentage have adapted too well and escaped cultivation. These plants have become established, or naturalized, in the wild.

Not every naturalized plant is a threat to native ecosystems, however. The BBG handbook Native Alternatives to Invasive Plants is concerned with those nonnative plants that not only establish viable populations in but also alter the structure and/or functioning of those ecosystems.

Many invasive plants are still being sold as garden specimens or for wildlife plantings and erosion control, despite their documented ability to degrade natural areas. And although no system is in place to effectively screen them for potential invasiveness, new plants from around the world are constantly being introduced to satisfy the preoccupation with the new and exotic that has characterized horticulture for at least the past hundred years.

The more we learn about invasive plants, the more we realize how difficult they are to control, much less eradicate. The most prudent course of action clearly is to avoid planting these species in the first place.

Since BBG’s original handbook on invasive plants was published, we have received numerous requests for a companion volume featuring ecologically safe alternatives. The Encyclopedia of Native Alternatives to Invasive Plants, at the heart of this book, recommends a variety of beautiful, regionally native species that fill the same needs as the worst nonnative invasive plants commonly used in horticulture.

If you select these species, it is highly unlikely that you will be unleashing North America’s next invasive menace. Regional natives aren’t the only ecologically responsible choices; nonnatives that have been planted in gardens for decades without demonstrating any signs of invasiveness are good candidates for landscaping as well.

But by selecting regional natives you will be preserving the natural character of your area. You will also be preserving the complex interrelationships between the native plants and the butterflies, birds, and myriad other creatures with which they have coevolved.– Brooklyn Botanic Garden

Can Golf Courses Become Nature Preserves?

Monday, June 28th, 2010

AMONG the things you might find in a golf course pond are errant balls, clubs hurled in anger and native amphibians

Golf courses are among the most manufactured of all landscapes: manicured greens, rigorously mowed fairways and chemical-laced ponds. “In essence, golf course managers are one-crop farmers; they grow grass,” says Kevin Fletcher, executive director of Audubon International, a group dedicated to promoting golf courses as nature reserves (and no relation to the bird-, though not necessarily birdie-loving National Audubon Society).

Such an obsessive focus on grass, not to mention on knocking tiny white balls into little cups in the midst of verdant scenery, might not seem like the ideal setting for animal life. But new research, funded by the United States Golf Association (USGA), shows that water hazards, the bane of many a duffer’s handicap, may provide a refuge for native amphibians, raising hopes that these human-dominated landscapes can provide them another habitat.

“We went into this thinking that golf courses were going to be pretty nasty places,” admits biologist and occasional golfer Ray Semlitsch of the University of Missouri–Columbia. “We started out with the idea that we’d be studying the effects of chemical contamination. Golf courses, from our perspective, seemed to be a place where there were a lot of chemicals used.”

But those very chemicals may have actually helped the three amphibians studied: American Toads, Southern Leopard Frogs and Spotted Salamanders. Researchers placed 10 boxes containing quantities of amphibian young in four ponds—two on golf courses and two in chemical-free U.S. Geological Survey ponds.

To their surprise, the amphibians reared in the golf course ponds did better than those in the protected ponds. “One hypothesis is that contaminants used at the golf course sites could be negatively impacting invertebrate populations,” but not the amphibians, says biologist and study co-author Michelle Boone of Miami University in Oxford, OH. “Insects are more sensitive to insecticides than are most vertebrate species.”

A chemical test conducted at the end of the summer experiment found no traces of contamination but they could have been present early in the season, Semlitsch argues. With fewer dragonfly and beetle larvae about, more of the three amphibians could survive to maturity as these insects are “voracious predators,” he says.

The amphibians in the golf course ponds also only thrived there if no Bullfrog tadpoles were present. These typically larger amphibian offspring dominate man-made ponds throughout North America, gobbling up all available food, including their smaller peers, biologists say.

It remains unclear, however, whether the three amphibian species could complete their life cycles on the course. One of the test courses “would have to be changed radically to maintain those species,” Semlitsch says, but the other has “a fair amount of natural habitat, including oak-hickory forest and native grasses. I think it could maintain a small population, perhaps. I don’t know how healthy they might be.”

Boone adds: “Amphibians associated with grasslands, for instance, may be more likely to be able to complete the life cycle on golf courses than forest-associated species, because there is more potential to maintain unmowed grassland areas than thick forests.”

Given the proliferation of golf courses—there are more than 17,000 in the U.S. alone—combined with recent legal decisions limiting protection of wetlands, they may become some of the last such refuges. The key will be mimicking nature. “What we’ve done,” Semlitsch says, “is create something that is totally artificial,” ponds that never dry. By drying the ponds long enough to kill Bullfrog tadpoles—a few days in late summer to match natural cycles—golf course managers could promote a broad range of biodiversity as amphibians and other species thrive in such temporary wetlands. This recommendation could work throughout the continental U.S., and even in Europe.

Other recommendations include letting grass grow tall around such waters to protect them from chemical runoff and provide habitat for the adult amphibians as well as connect them to undisturbed native environments. “Seventy percent of golf courses are nonplay habitat,” Semlitsch notes. “If you mix and mingle water features and adjacent natural areas you’ve got a good chance of playing a good game of golf and protecting those habitats.”

But it may be tough to get golf course owners on board with the plan. The USGA-funded Audubon International has only enlisted some 600 courses since 1991. “The superintendents on golf courses seem very open to taking some of the management strategies into account,” Boone says. “If the changes do not interfere with golfing and doesn’t take substantial additional work, then why not do it?” After all, mowing requires more work than not mowing.

But some might argue that a dry pond with an unmowed fringe is unsightly, if a boon to wildlife. And, regardless, such human-dominated landscapes are not the equivalent of undisturbed nature. “It’s not a substitute for natural areas or preserves,” Semlitsch says. Such preserves may not be large enough and alternatives should be found, even if they are chemically challenged man-made ponds.

“We could potentially do better than promoting the maintenance of one species, Bullfrogs,” Semlitsch notes, “to at least include a few other native species.” –Scientific American

California Redwood Confirmed as World’s Tallest Tree

Monday, June 28th, 2010

HUMBOLDT, CA– A 379.1-ft. tall redwood found in a remote section of northern California’s Redwood National Park is the world’s tallest tree, researchers confirmed last week.

The tree, named “Hyperion,” is the largest of three redwoods discovered this summer that eclipse the previous world record holder, a 370.5-ft. tall redwood named “Stratosphere Giant.”

The researchers suspected tree was more than 378 ft. tall, but held off on declaring it a world record until Humboldt State University botanist Stephen Sillett climbed the giant tree two weeks ago.

Laser range finders are fairly accurate devices, but it is not always possible to hit a tree’s highest leaf from the ground when using such a device. The most accurate means of measuring a tree’s height is to climb into its crown and lower a fiberglass tape from the top.

The climb was delayed until the end of the Marbled Murrelet’s nesting season. The endangered species of bird relies on old-growth trees like the redwood. When the murrelet’s nesting season came to a close, Sillett climbed Hyperion and verified its status as the tallest tree.

The Redwood Creek basin, where Hyperion is located, was thoroughly logged during the 1970s before Jimmy Carter’s administration redrew the boundaries of Redwood National Park– an act that silenced the chainsaws in that particular neck of the woods.

“If you look at a map, it’s just amazing,” said Sillett. “Most of Redwood National Park has been cut. There are really just a few drips and drabs of old growth left in there, and in these little bits that are left, there are these tall trees lurking–and we just found them. One of the amazing things about this discovery is that we learned that this park expansion in 1978 really did save the tallest trees. No one has realized that until this summer.”

The discovery is part of an ongoing collaboration between Sillett and two naturalists, Chris Atkins and Michael Taylor. The three have been searching the range of redwood to document all living trees over 350 ft. tall and have thus far found 136 individual redwood trees over 350 ft. tall. When they began their work in the 1990s, only about 25 such trees were known.

“The only reason these discoveries are made is that a group of people are willing to go out looking for them–I’m lucky to be associated with Michael Taylor and Chris Atkins,” Sillett said. “We thought we’d mopped it up, as far as finding the tallest trees goes. No one has ever seen anything like this. It’s the most significant discovery in tree height in 75 years. It’s been pretty miraculous.”
–ENS

Birds and Plants–An Ancient Collaboration

Monday, June 28th, 2010

By Mariette Nowak
OVER THOUSANDS of years, birds and plants have developed a mutually beneficial relationship.

Birds help to pollinate plants, disperse their seeds, and eat the insects that can ravage them. To entice birds to do this work for them, plants have evolved colorful, nectar-filled flowers and luscious, nutrient-packed fruits and seeds to nourish them. In addition, their limbs and leaves offer nesting sites and cover.

Why landscape for birds?

“Small ‘islands’ of habitat can provide food resources to birds, particularly during migration.”, Victoria D. Piaskowski, International Coordinator, Birds Without Borders – Aves Sin Fronteras, Zoological Society of Milwaukee.

Habitat loss is the single most important cause of the decline of species! Your yard, whatever its size, can offer habitat for birds. Many birds seldom or never use feeders, preferring natural foods.Feeder birds get only a relatively small portion of their nutrition from feeder food

Why plant natives?
“Native plants, which have co-evolved with native wild birds, are more likely to provide a mix of foods–just the right size, and with just the right kind of nutrition–and just when the birds need them.” Stephen Kress, National Audubon Society

Researchers have found that native plants are better for birds and for the insects they need for survival. Some of their findings include the following:

  • There are more bird species and greater numbers of birds in areas with native species than in areas with exotic, or non-native, species.

  • Birds nesting in non-native shrubs, like buckthorn and honeysuckle, are more likely to fall victim to predators such as cats and raccoons than birds nesting in native shrubs. This is due to the branching and other characteristics of the non-native shrubs.
  • Cedar Waxwings that eat the berries of one species of non-native honeysuckle develop orange, rather than yellow tail bands. This color change could be harmful to the birds, since they use color in mate selection and territorial disputes
  • Most insects, so important for bird nutrition, prefer their native host plants and, in fact, often lack the enzymes needed to digest non-native plants.
  • Native wildflowers often offer significantly more nectar for hummingbirds than the cultivated hybrids that have been derived from them.
  • The great variety of native species, which provide food for birds throughout the year, is being replaced by a very limited number of invasive non-native species. These invasives offer food of reduced variety, quality, and seasonal availability.

What are native plants?
Native plants are those which existed in an area prior to European settlement. These plants are well adapted to the climate, precipitation, soils, insects, and other local conditions and are consequently easier to grow than non-natives. For information on the plants native to your area, check with your local nature centers, colleges, universities, Wild Ones Natural Landscapers (www.for-wild.org), and your state department of natural resources or similar agency.

Where to get native plants?
Native plants and source lists for native plants are often available at local nature centers, native plant nurseries, chapters of Wild Ones Natural Landscapers or native plant societies. Some states, like Wisconsin, maintain lists of native plant nurseries, seed suppliers and consultants.

Plants should be purchased from reputable suppliers
not dug from the wild. It is, in fact, illegal to remove plants from public lands. In the case of private lands, be sure to get the landowner’s permission. For “Guidelines on the Selection of Native Plants,” see the Wild Ones Natural Landscapers website (www.for-wild.org).

Getting Started
Take an inventory. For full yard restorations, you may want to let neighbors know what you are doing and check with officials regarding local regulations.

  • Test your soil, a service which may be offered through your county university extension service.

  • Keep the native plants in your yard; remove the invasive exotics.
  • Mimic the multiple layers of growth found in many natural settings: trees, shrubs, vines and herbaceous plants.
  • Select plants that will provide berries, seeds, and nuts during different seasons.
  • Provide evergreens for winter shelter.
  • Keep dead trees, standing or fallen, to provide insect food, cavities, and perching sites for birds. The branches of dead trees can be removed if they are dangerous.
  • Create a brush pile to provide shelter.
  • Leave at least some leaf litter for ground-feeding birds, who will scrape through the litter for insects.
  • Stop using herbicides and pesticides, which can be ingested by birds as they feed on insects and plants. Also, don’t use rodenticides which will harm birds of prey when they feed on animals that have ingested the poison in bait.
  • Limit or eliminate your lawn for less mowing, fertilizing, watering, and pollution and to make more room for natives

Additional Possibilities
“Some habitats are of particular interest to backyard birdwatchers because small examples can be replicated in backyards, including freshwater marshes, ponds, brooks, wooded swamps, bogs, woodlots, pine barrens, streamside forests, thickets, prairies, deserts, and alpine meadows.” Donald S. Heintzelman, The Complete Backyard Birdwatcher’s Home Companion.

  • Restore or recreate the habitat(s) once native to your area – woodland, wetland, prairie, or savannah, etc. – which will attract birds native to those habitats.
  • Create habitats for particular birds: a hummingbird garden, a migratory bird stopover, a bluebird haven, a woodland bird retreat, a finch garden (prairie), a winter bird area, or a wetland bird habitat.
  • Regardless of the size of your yard, you can help reverse the loss of bird habitat. By planting the native plants upon which our birds depend, you’ll be rewarded with a bounty of birds and natural beauty just beyond your doorstep.

Protect Your Birds
Keep your pet cats indoors and urge your neighbors to do so. Cats kill millions of birds in Wisconsin each year and it has been documented that bells and declawing are mostly ineffective in preventing this predation. For more information, see American Bird Conservancy’s brochure: Cats Indoors!. –Wild Ones

Birch Trees Shining Bright

Monday, June 28th, 2010


LET’S FACE IT, birch trees have it easy nowadays. There was a time when their can’t-be-missed white bark made them the most useful and practical trees in the forest.

American Indians used the paper-like peeling bark when making canoes, baskets, utensils and wigwam covers. And early lumberjacks used birch bark as waterproofing underneath the cedar shingles of their bunkhouses.

Today, birch trees in the landscape setting lead much more regal and pampered lives. Their strikingly attractive bark and lovely leaves, especially in fall when they turn golden yellow, make them natural standouts among other backyard plantings.

Most birches are native to northern parts of the United States and southern Canada. In their natural habitat they’re often found in cool moist areas along riverbanks, where they get plenty of sunlight. Taking cues from their natural setting is the secret to making these beautiful trees work in the yard. Without lots of moisture and sunlight, birches are destined to struggle and eventually fall prey to their No. 1 enemy—the bronze birch borer.

The destructive larvae of these beetles tunnel into birch trees and interrupt the flow of sap, eventually killing the trees. The good news is well-maintained healthy birches are more resistant to borers and other less damaging yet persistent pests, such as leaf minors and aphids, that feast on the foliage.

The most important thing you can do to protect birches is provide plenty of moisture. This keeps the trees stress-free and strong, and the pests move on to feast on weaker trees.

While birch trees are fast growers (they grow up to 2 feet each year), they are relatively short-lived trees and rarely top more than 60 feet. Before purchasing one for your yard, first determine if you can meet its needs.

Birches prefer full sun to partial shade in woodland settings and can be planted in groupings as they appear in the wild. To take full advantage of their beautiful bark, plant them in front of a backdrop of evergreens where they’ll stand out all year long.

Because tree roots spread wide and shallow, dig a planting hole about 3 to 5 times wider than the root ball. Locate the root flare (the bulge above the roots) just above the soil line after removing the tree’s container or burlap. After planting, mulch 2 to 4 inches deep around the tree, but keep it from touching the trunk.

Deep water your birch weekly during the growing season, especially during dry spells. A great way to ensure thorough watering is to place a soaker hose around the base of the tree’s drip line (the width of its upper branches) and water for several hours.

It’s best to prune the trees during their dormant season. In the late winter, pruning will be messy because of the free flow of sap, but it won’t harm the trees.

Yes, birches take a little more care and consideration than other backyard trees. But if they work in your yard, you’ll find few trees that reward your effort the way birches do.  –Birds and Blooms