FOR much of the 19th century, scores of French painters, laden with knapsacks and portable easels, trekked through the Forest of Fontainebleau to capture the shifting wonders of nature with their brushes right on the spot. Some came for weekends; some stayed for a lifetime.

Pioneers of the new art called photography, laden with even more equipment, made the pilgrimage as well. So did the young Impressionists. Together they all raised the art of landscape to new heights in France.

A generous sampling of this work is on display in an exhibition at the National Gallery of Art that celebrates a place rather than a painter. Called “In the Forest of Fontainebleau: Painters and Photographers From Corot to Monet,” the show closes June 8 and goes on to the Museum of Fine Arts in Houston in July.

The place celebrated is a forest that was once the hunting grounds for the royal chateau in the town of Fontainebleau. More than 40,000 acres in area and more than 50 miles in circumference, the forest, now a national park, is small by American standards -- Yosemite National Park is 17 times greater. But the forest of Fontainebleau is only 35 miles southeast of Paris and thus near the center of the French art world in the 1800s. And the forest offered all that a painter or photographer might want: a grand array of different kinds of massive antique trees, incredible rock formations soaring one way and cascading another, wildflowers, patches of flat plains, and shepherds and peasants on its edges.

Looking at 100 paintings, pastels and photos of the same site may sound tiresome. But, in fact, there is extraordinary variety. Some artists concentrated on the wild formations of rock; others on the contortions of trees. Théodore Rousseau liked to depict the changes wrought by seasons and times of day. Jean-François Millet preferred to show the dignity and exhaustion of laborers. Even renditions of the same scene have a special fascination when worked by different painters or by a painter and a photographer.

Jean Baptiste Camille Corot is credited with the discovery of the forest as a laboratory for art. Like other French landscape painters, Corot often made lengthy excursions to Italy to find exotic scenery. But he soon realized that he had all the variety and scenic spectacle he needed much closer to home. Corot’s eye for the dramatic is demonstrated in his painting of a wildly splintered remnant of a tree, “Study of a Tree Trunk in the Forest of Fontainebleau” (1822).

Corot and the others who followed him to the forest differed from traditional French artists who made sketches outdoors but painted their canvases in studios, sometimes using landscape only as background. The new painters, who wanted their scenes realistic, worked on their canvases in the forest itself.

The best known of these “plein-air” or open-air painters used the village of Barbizon as their base for excursions into the adjoining forest. Although a contemporary guidebook described Barbizon as “a rather ugly hamlet,” painters gravitated there because of an inexpensive inn set up by an enterprising village couple who liked the company of artists. Millet and Rousseau later moved into the village.

“The Angelus” (1857-59), Millet’s renowned painting of two peasants standing at prayer in their field, was so popular it became a 19th century icon, reproduced countless times as a postcard and as a Christmas card. Salvador Dali, obsessed by the work, painted several variations of it in the 20th century. “The Angelus” is not included in the show, but there are more than a half-dozen similar portrayals by Millet of peasant life, including “The Sower” (1865-66) and “The Potato Harvest” (1854-57).

‘Taste for the old forests’

ROUSSEAU was the Barbizon painter most devoted to re-creating the natural scenery of the forest. He had a mystical feel about the twisting rock and massive trees and, as he put it, a “taste for the old forests.” In his “The Gorges d’Apremont” (1857), which he submitted to the Paris Salon, Rousseau wrote he wanted to paint the vegetation’s “stages of triumph over the barrenness of the soil.” While there were 20 landscapists at the Salon who drew and painted better than Rousseau, the critic Théophile Gautier wrote, “No one makes the sap run through the trunks, the grass, the mosses as he does.”

The judges of the annual Salon were the arbiters of taste and craftsmanship, and artists submitted their latest work for prizes, prestige and potential sales. The number of Fontainebleau landscapes at the Salon rose from 19 in 1833 to 42 in 1857 to 77 in 1880. In all, the Salons of the 19th century exhibited 1,800 paintings of the forest.

Anyone interested in landscape art had to make the pilgrimage to the forest, whether an amateur, a photographer, an established painter such as Gustave Courbet, or a budding Impressionist such as Pierre Auguste Renoir or Claude Monet. Gustave Flaubert, George Sand and other novelists used the scenery as the setting for their plots.

Tourists began crowding the forest after the rail line from Paris reached there in 1849. Before then, the trip by horse and wagon or by Seine River steamboat took six to eight hours. The train cut the trip to about an hour.

Photography had developed only a decade before the rail line reached the forest. Pioneer photographers, many of them artists as well, soon began lugging their heavy equipment there in hopes of capturing images of the tangled scenery. The results demonstrate, says Sarah Kennel, the National Gallery’s assistant curator of photographs, that “from its earliest stage, photography was deeply engaged in the pressing artistic questions of its time.”

Photographers faced tiring obstacles. Some used glass negatives that had to be coated right there in lightproof boxes before every shot. The problem was eased somewhat by the invention of paper negatives that could be coated ahead of time in the studio.

There was a collegial atmosphere in the artist colonies by the forest, and the painters and photographers learned from one another. One of the dividends of the National Gallery show comes from seeing paintings and photographs with similar subjects displayed near one another. The menace of the sky in Eugène Cuvelier’s photo “Storm, Fontainebleau” (1860) is caught in much the same way by Barbizon artist Narcisse-Virgile Diaz de la Peña in his painting “Stormy Landscape” (1872). In a similar example, there is an obvious resemblance in the way Gustave Le Gray photographed the forest road to Chailly in 1852 and how Monet painted it in 1865.

The influx of tourists, armed with new guidebooks, irritated the artists. A profusion of promotional signs showing the paths and identifying sites made matters worse. The forest even sprouted food stands. In a cartoon in a humor magazine in 1864, the caricaturist Cham drew an irate artist throwing a rock at a tourist for accidentally shaking a leaf the artist was painting.

Rousseau was so fed up by tourist promotion, commercial logging, quarrying and other interference with the natural scenery that, on behalf of all the artists, he petitioned Emperor Napoleon III for relief. In 1861, the emperor agreed to set aside a large portion of the forest as a nature preserve. Believed to be the first such preserve, it set a precedent for Yellowstone National Park, which followed 11 years later.

The forest is still one of the most popular attractions in France. Hundreds of Parisians drive there each weekend, park somewhere on the forest’s rim and take one of its many trails. The home of Millet still stands, transformed into a small museum. There is one great difference with the 19th century: Since landscape is not a hallmark of contemporary art, only a handful of painters can be found on a typical day, far outnumbered by the tourists.