Frost is on the pumpkin, leaves are changing hue, and somewhere in the countryside, paulownia tree rustlers are tuning their chain saws. A top-grade Paulownia qomentosa log can bring hundreds or even thousands of dollars because the wood is so highly prized in Japan. There it is used for many things, especially the traditional bridal chest, or tansu. Fall brings out the paulownia rustlers because the pale wood is no longer discolored by the sap that flows in warmer weather. "Now's the time, when the colder weather starts coming, that people should be more aware," said Lt. Tommy Buckler of the Calvert County Sheriff's Department. Last November, Mr. Buckler and other Calvert County officers investigating a paulownia theft caught three Anne Arundel County men who smelled of gasoline and were covered with wood chips. The chips were later identified as paulownia. In August, the trio pleaded guilty in Circuit Court to felony theft. Each got a 6-month jail term, with all but two weeks suspended. They were placed on five years' probation and ordered to pay $7,077 in restitution. It was no isolated case: * On a Sunday morning in early August, Sam A. Carr, an electrical contractor in Montgomery County, discovered a stump his property in Barnesville where a 30-foot paulownia had stood the night before. Natural Resources Police put the tree's value at $3,000, although the wood may have had too much sap to bring a premium price. * Last October, a Rising Sun man pleaded guilty to cutting down 13 trees in the state's Fair Hill Natural Resource Area and selling the wood to a Delaware sawmill for $1,748. In exchange for the plea, Cecil County prosecutors dropped felony theft charges that could have meant 15 years in prison and a $100,000 fine. Instead, the poacher received a misdemeanor conviction, an 18-month suspended jail term, a $500 fine and three years' probation. * In the past year, Detective Jim Morrissette of the U.S. Park Police has investigated at least six paulownia-poaching cases, leading to prosecution of four suspects. "This is big money," he said, "and their [criminal] records look just like every other hoodlum out there -- convicted felons, burglars, drug convictions . . . firearms [violations] and assaults." The cases are pending. An Asian native, the fast-growing paulownia took root in America in the 19th century, when seed pods -- used as packing material in China -- spilled from docked ships and railroad cars. Westbound settlers also planted the sweet-smelling tree, and the rot- and warp-resistant wood has been used for duck decoys and dulcimers. But mostly it was considered a "trash" tree. Then, in the 1970s, Japanese buyers began paying thousands for high-quality logs. Their native trees -- called kiri -- had been wiped out by a blight. In Japan, parents once planted a kiri tree when a daughter was born, then had the wood fashioned into a 5-foot to 6-foot tansu that was presented to her as she prepared to marry. Today, a tansu sells for the equivalent of $10,000 or more, limiting the bridal tradition to the affluent, says Kazuhiro Tajiri, cultural attache at the Japanese Embassy. To fetch top prices, paulownia logs must be straight, at least 10 inches thick, with the tight grain that comes through slow growth a crowded forest setting. Wide grain, sap discoloration, rot and insect damage or distortion from many limbs make a log less desirable. Today, first-rate logs may sell to a lumber merchant for as much as $10 to $15 a board foot, dealers say, making paulownia the most valuable wood in the Eastern forests. A 12-foot log, 20 inches across at the small end, would hold almost 200 board feet and bring $3,000. (A board foot is a standard measure, 12 inches square and 1 inch thick.) Dr. Peter Beckjord, 48, is founder of the one-man National Paulownia Center in Beltsville. The former University of Maryland forestry professor has spent 14 years studying and promoting the paulownia as a cash crop and a nifty solution to global reforestation problems. He has heard from many swindled property owners, many of them retired farmers and widows. "They are living on a small pension, or Social Security, and if they have a tree sitting on their property worth $7,000, that's a windfall," he said. "And I have seen so many people ripped off." bTC Many owners report that they were paid $50 or $100 by itinerant loggers who offered to take down a tree for them. Often, trees are stolen after owners reject a logger's offer to buy. Investigators say that some rustlers scout paulownia trees -- sometimes from airplanes -- in spring, when large purple flowers give them away. In the spring of 1991, thieves drove a truck and trailer onto James H. Ruff's Bel Air farm at 4 a.m., cut down eight trees and hauled them away. Two weeks later they came back and cut two more trees, but were frightened off before they could load them. Fed up, Mr. Ruff said, "I sold what few I did have left." It's not clear what proportion of the $10 million in paulownia logs exported every year are stolen, Dr. Beckjord said. There are some legitimate paulownia "concentrators" who offer a fair price. But he estimates that "a very large percentage" of the wood has been harvested illegally. Police response to paulownia poaching ranges from diligent to indifferent. Mr. Morrissette of the U.S. Park Police said that his investigations have yielded clues that he has passed on to police in various jurisdictions. "They politely told me that after they get through handling all the crimes against persons, they don't have time to do paulownia trees," he said. On the other hand, in Virginia, Madison County sheriff's investigator W. R. Jenkins said that paulownia theft in his county north of Charlottesville "never was anything to laugh off." He said some cases have been solved by clever police work -- matching the fracture or the rings on the stumps to those on the logs. Suspects have been convicted of larceny. Madison County lumber dealer Robert Jenkins (no relation to W. R.) said, "I was having a deputy or somebody coming into my yard about every week when this thing was booming. I was standing more in court testifying against people instead of buying logs, and that ain't good." Finally, he said, "I started taking pictures of them behind the truck with the logs in the truck." The poachers got the word, he said, "and they didn't come around no more." Hardwood dealer Don Kendall of Troy, Tenn., said that high prices have made paulownia trees scarce. "Three years ago I was buying 15,000 to 20,000 [board-]feet a week," he said. "Now, it might be 1,500 feet a week." Years ago, some loggers bought for 10 cents a board foot and sold for $5 a board foot. "I know some who got filthy rich off this," he said. But as the trees disappear, landowners have become less likely to be swindled out of remaining paulownia trees. Today, Mr. Kendall said, "People pretty well know what they're worth." VALUABLE TREES Paulownia tomentosa Also imperial, Empress or Kiri tree. Named for Russian princess Anna Paulovna (1795-1865), who became queen of the Netherlands. Close relative: Catalpa Origin: China, Japan. Height: Max. 60 feet. Trunk: Up to 3 feet in diameter. Bark: Medium gray and flaky. Young growth is olive brown to pale Burgundy. Leaves: Heart- or spade-shaped, 6 to 12 inches wide. Flowers: Foot-long clusters of fragrant, lavender trumpets. Seeds: Tiny winged seeds spring from brown oval pods. U.S. Range: Extensive in South, but found as far north as New England.