It's the season of the trees. After all their hard work keeping things green and cool this summer, deciduous trees are putting on their final performance of the year. Now, while they're flaunting their finest costumes, is an appropriate time to take stock of what trees do for us. It is also a good time to plant new trees for the generations to come.

We appreciate trees for their magnificence and beauty through the seasons, but it's easy to forget all the ways they contribute to our quality of life. A handsome tree in the front yard makes a house a much nicer place to come home to. Oaks, maples, lindens and other deciduous trees lining city streets shelter whole neighborhoods and fill them with character. Trees mark ancient trails and punctuate contemporary landscapes, subtly defining our view of the world.

Trees are one of the most massive elements of our environment. In the process of photosynthesis, they remove carbon dioxide from the air and replace it with oxygen. Their extensive root systems filter the water in the soil. Trees provide food and shelter for wildlife, especially birds and the insects they need to survive. Without trees, the world would be dreary and inhospitable.

With increasing urgency, arborists and urban foresters are studying trees in cities, public gardens, parks and the countryside to try to determine which trees are the most adaptable to changing climate conditions, including extreme weather events such as droughts and flooding. The Chicago Botanic Garden started its Trees for 2050 project specifically to help the garden decide how to replace about 400 trees recently lost to infestations of the emerald ash borer. Of 50 different kinds of trees at the botanic garden, the study found that 40 of the native and well-adapted exotic species remain good choices until 2050, says Phil Douglas, curator of woody plants at the garden. By 2080, as the climate continues to change, only 11 of the species in the initial study will continue to thrive in Chicago and the Upper Midwest, he says. The Garden's research resulted in an interactive online database to help residents of Chicago -- and throughout the Midwest -- make the best choices for their home gardens.

Gingko, pecan, zelkova and parrotia trees are among the most adaptable and viable trees for the long term in the Midwest, Douglas says, but these trees are just a starting point. Much more work needs to be done to identify the best trees for the Midwest's changing climate, and for every area of the country.

Shawn Kingzette, an arborist with the Davey Tree Expert Company and a regional manager for the company in the Chicago area, recommends diversity, above all, to help ensure a future with healthy trees. "It's not enough to plant native trees that can resist bugs and blights," he says. "Natives are susceptible, too." A diverse tree population provides resilience, Kingzette says -- so if you love dogwoods or redbuds, plant one, by all means, or even three, but not a dozen of them in your home garden, or you risk losing your whole planting. Urban foresters learned this the hard way when elm blight drastically changed urban landscapes years ago. The emerald ash borer infestation has reminded them again, vividly, of the possible consequences of over-reliance on a single species.

Careful planting -- avoid planting under utility lines and too close to houses, sidewalks or driveways -- will also help ensure that trees have a long and healthy life. It is important to choose trees that fit their spot, Kingzette says. A small tree, such as a fringe tree, is likely to be a more appropriate choice near a patio than a towering oak. Sweet gum trees, with their prickly fruits, are great habitat trees, but don't plant them near a sidewalk.

A warming climate will expand the choices in colder areas, allowing warm-zone trees, such as crape myrtles, to thrive farther north, but "don't just plant southern species -- plant tougher species," Kingzette suggests. Turn to your local horticultural extension experts for their recommendations.

If you're planting a tree, consider planting on the south or west side of your house, where a deciduous tree will keep your home cooler in summer and allow the sun's warming rays through in the winter, to save on utility bills. Three trees placed strategically around a house can save up to 30 percent on energy bills, according to the U.S. Forest Service. Small trees that shade air-conditioning systems help the units cool more efficiently.

Fall is an excellent time to plant deciduous trees, which take advantage of the cooling season, even after their leaves have dropped, to establish healthy root systems. Trees planted in fall will get off to a good start in spring because their roots will already have reached down to moisture deep in the soil. Larger specimens may not show much top growth their first year or two, but they are adapting to their new circumstances. Water well after planting, once a week if necessary (until the soil freezes, if you're in a cold climate), while trees are becoming established.

Even small trees make a significant contribution to any landscape, with spring blooms, pretty summer canopies of leaves, rich fall color and lovely, sculptural shapes in the winter. Berries and nuts feed birds and squirrels through the winter. Trees also have economically tangible yields: Online tree-benefit calculators let you type in the kind of tree you have, its size and your location, to determine the monetary value of trees and remind you that curb appeal -- and property values -- go up when pretty trees are part of the picture. Plant now, and when spring comes, you can give yourself plenty of credit for a wise investment, the returns on which are actually far greater than the cash calculators can project.

SOURCES

-- For more information about the Chicago Botanic Garden's Trees for 2050 project, including a list of trees, go to: chicagobotanic.org/plantinfo/tree_alternatives

-- The Arbor Day Foundation has tree-planting tips and information about trees and climate change: arborday.org/trees/climatechange/fightHome.cfm.

-- To calculate the value of trees in your garden, try one of the tree-benefit calculators listed on the Holden Arboretum's website: holdenarb.org/horticulture/calculate-the-value-of-a-tree/

-- The Davey Tree Expert Company is a national company of arborists and tree experts, with residential and commercial services: davey.com.

It's never too soon to think about spring. On bright fall days, let the clear sky and golden colors of the harvest season inspire you to plan ahead for a glorious spring. All you need to bring it off is a few dozen flower bulbs.

Daffodil, tulip, crocus and other bulbs that bloom in spring should be planted in the fall. Finding places for them in the garden is easy, and planting them is not a chore. It's a pleasant season to be out in the garden after the heat of summer abates. Working by yourself -- or, even better, with a friend -- you can plant hundreds of bulbs in less than an hour. An investment in bulbs this fall is a fail-safe bet for a colorful spring.

Start your bulb investment with a few handfuls of crocus bulbs. They're about the size of a pearl onion, and you can plant a dozen of them in a hole only 4 inches deep and 2 or 3 inches across. Toss the bulbs in the hole, cover them with soil, and tamp the soil back down with your foot. If you suspect mischievous squirrels might dig up the bulbs, place a brick or two on top of the soil -- just remember to remove it after a couple of weeks, so the bulbs can come up in the spring.

Crocus and other tiny but delightful bulbs look pretty along a path, where you're sure to see them when they bloom. You can tuck a few of these little charmers in near a garden bench or plant them around the edge of a patio, where they will tempt you out into the garden in early spring. These small flowers make a surprisingly bright and cheerful display, even from the street.

The earliest spring bulbs are followed by the magnificent daffodils, bold and hardy flowers unafraid of the lingering chill in the air. Daffodils grow from crinkly bulbs about as big as your fist. Most varieties produce just one showy flower per bulb, but jonquilla types, which are often fragrant, produce up to six smaller blooms from every bulb.

If you're familiar only with yellow daffodils, now is the time to experiment with something new -- those well-known golden trumpets are just the beginning. Snow-white daffodils are sleek and stylish; flowers with bright orange cups and yellow petals seem to positively glow. Double daffodils, which have frilly centers instead of traditional trumpets, will put you in mind of roses or camellias. There are hundreds of choices on the glossy pages and stunning websites of mail-order bulb specialists. Garden shops will have bins of daffodil bulbs stacked in the aisles beginning around Labor Day.

Daffodil bulbs are larger and should be planted deeper than the little bulbs -- 6 to 8 inches deep. It is easier to plant them with a spade than with a trowel, and it's more fun to plant them with a friend. One person lifts the soil with the spade, and the other shoves the bulbs in the ground. If you're planting by yourself, you can use the same method -- it will just be a little more time well spent.

Plant daffodils under trees (they will bloom before the trees leaf out) or among shrubs and perennials in a mixed flower bed. They make a good impression in a mailbox garden out by the curb, and they're friendly and inviting along a path or a front walk. Daffodils will come back year after year -- and with more blooms -- if they are planted in a spot that does not receive much summer watering.

Just before the daffodils finish blooming, the tulip season begins. These flashy flowers, each elegant bloom about the size of a teacup, stand tall on graceful stems. Tulips may look like precious jewels, but they're decidedly affordable: for $30 or $40, you can buy 100 bulbs, which, when they come into bloom, is enough to knock your wooly socks off. It's hard to go wrong with tulips. Look for colors you like, or buy a mixture and plant them together. Most bulb specialists offer pre-selected mixes of tulips designed to bloom together all at once for a glorious display, or over a period of weeks in a show that develops over time.

Tulips are at their best in clusters of five or more bulbs. A display of 100 planted together in one area, such as near the front door or at the end of the front walk, will stop traffic. On the other hand, single bulbs planted here and there throughout a flower bed have the charm of wildflowers. They're also gorgeous in groups in flowerpots. If you live in a mild-winter climate, where a pot can spend the winter outdoors without frost damage, try planting 25 tulip bulbs in a big pot. In colder climates, tulip bulbs in a pot can be buried in a pile of autumn leaves all winter and then brought into the light in spring.

From the first tiny crocus blooms to the last gorgeous tulips, the spring flower bulb season lasts for months. It only takes one morning in the garden in the fall to set yourself up for an unforgettable show of spring blooms. You won't see the results of your work immediately, but an autumn morning in the garden is its own reward -- and then when spring comes, you can give yourself plenty of credit for thinking ahead.

Sources

Garden shops stock up with spring bulbs of every description in the fall, offering dozens of varieties of tulips, daffodils and crocuses. For the biggest selection, shop online. These bulb specialists offer terrific variety and top-quality bulbs at great prices:

-- Brent and Becky's is well known for daffodils of all kinds, but also for a great selection of tulips and other spring bulbs: brentandbeckysbulbs.com.

-- If you're looking for tulips in a wide assortment of combinations, turn to Colorblends. The company offers dozens of sure-fire tulip blends, many other spring bulbs, and high-quality planting tools: colorblends.com.

-- John Scheepers is another excellent source of spring bulbs of every description: johnscheepers.com.

Water makes a garden sparkle, and it doesn't take much to capture the effect. In gardens of every size and style, you can make quite a splash with nothing more than a birdbath.

Fancy fountains and elaborate ponds full of fish completely change the character of a garden. Small water features are subtler and more personal. The glint of a pretty birdbath draws your eye, even from across the yard. It will instantly add a quiet note of tranquility, but it also brings color, life and movement to a garden: A birdbath is one of the best and easiest ways to attract birds of all kinds. And setting up a birdbath doesn't require elaborate design skills, a big budget or even a toolbox.

Finding a spot for a birdbath is easy and fun. You should be able to see it from inside the house, if possible, and from wherever you usually sit outdoors. A classic birdbath on a pedestal can be placed right in the middle of a flower bed -- or it can stand in a sunny spot all to itself. You can tuck a birdbath into a niche along a garden path, perhaps near a bench, inviting you to linger, or you can make a place for a birdbath right next to the patio. Where space is at a premium, you can hang a birdbath from a branch or a sturdy crook. You can even attach a birdbath to a deck rail or a windowsill. Out in the open, a birdbath shimmers in the sunlight and reflects the passing clouds. The birds will particularly enjoy a more intimate bath in the dappled light under trees.

When you're looking for just the right spot, keep in mind that the birdbath must sit level with the ground. If your yard slopes or the soil settles under base of the birdbath, a few paving stones or bricks will help maintain an even water level in the basin.

All birdbaths are great garden decorations. A birdbath on a pedestal is inherently sculptural and becomes a natural focal point in a garden, so place it thoughtfully to take full advantage of it. Colorful glazed birdbaths complement summer flowers and add bright notes through the winter. Low birdbaths made from a plant saucer or any large, shallow dish fit naturally into more informal gardens. A gleaming metal birdbath will reflect the spirit of a formal modern garden design.

Birds are easygoing about garden design and happily visit all kinds of birdbaths, even puddles. Nature seems even closer and more beautiful when a colorful parade of birds visits your garden all year round, coming in for a sip or a dip, splashing in the shallow water and preening afterward in the branches of a nearby tree. If you're already feeding cardinals, blue jays and chickadees, you may be surprised to discover that a birdbath attracts an even wider variety of birds. If you haven't tried it before, a birdbath will introduce an important new dimension to your backyard environment.

Birds like to drink water every day, and they'll quickly make a clean and fresh birdbath a part of their daily routine. A birdbath also helps birds cool off and keep their feathers tidy. In nature, birds look for shallow puddles after a rain, or for any depression in a log or a rock. A good birdbath is like a puddle -- it should be less than 3 inches deep, with gently sloping sides. If your birdbath is a little deeper than that, place a few flat rocks on the bottom for the birds to stand on.

To make a birdbath even more attractive to birds, add moving water. A drip or mist attachment (available at garden shops and bird specialty stores) changes the dynamic a lot, adding a soothing splash that birds can hear from the treetops, or a spray that catches their eye from a distance. Small birds perch on the tip of a drip attachment to take a sip, as though they're at a drinking fountain. With a mister, you're likely to see hummingbirds dart through the mist for a quick shower as they flit about the garden.

In a sunny spot, water will evaporate quickly from a birdbath in the summertime, so you'll need to keep a watering can or a hose handy to top up the basin; it's a pleasant part of the daily garden routine. In shade, clean out any leaves or twigs that fall into the water. Refreshing the water every day or so also prevents mosquitoes from breeding in a birdbath.

Fresh water is a secret ingredient: It makes any garden more interesting and attractive. Putting in a birdbath -- or two, or three, around the garden -- is an intimate gesture that you and the birds will appreciate every day.

SOURCES

Birdbaths of all kinds are available from:

-- Gardener's Supply Co., gardeners.com

-- Wild Birds Unlimited, wbu.com