The tree, a monarch Chestnut Oak with dark, naked limbs that reach upward nearly 80 feet, stands apart on the side of a Virginia hill. People who know trees say the oak has been standing on the hill for 200 years.

The bulldozer, a yellow earthmover that arrived March 16, is digging about 20 feet from the tree trunk a foundation for a two-story, colonial-style, five-bedroom, $150,000 brick house.

Last year people who love the tree thought Fairfax County promised them nothing would be built near it. County Supervisor Warren I. Cikins (D-Mount Vernon) told constituents the tree was safe. The developer, however, gave no promise not to build and violated no law when the bulldozer started scraping dirt near the tree.

The tree is not dead, but there is great disagreement over whether it has been damaged by the bulldozer working next to its roots.

"Let's face it, the tree is a political thing," said the developer, Edward Fuehrer, an executive with A.G. Van Metre Inc. of Alexandria.

"The whole issue (of the tree) makes me look like an idiot," said Cikins.

"I simply do not believe that what is happening around that tree is good for it," said the Rev. David E. Bumbaugh of Mount Vernon Unitarian Church.

Bumbaugh, who has spoken of the oak from his pulpit, has been an advocate of the tree, which stands in the Mason Hill development off Fort Hunt Road in eastern Fairfax County, since he wrote a letter to the county arborist back in August 1976.

He asked why the tree must be a victim of development. The arborist, Richard Hoff, and the county asked the same question of the developer, and the plan to build a house on the land where the tree stands was stopped.

The minister and the politicians said they had not worried about the tree until the bulldozer arrived. They said they assumed the county told the developer there could be no house near the tree. In fact, the county had told the developer there could be no house built that would kill the tree.

The Chestnut Oak, known to tree buffs as Quercus montana, sends its roots almost straight down, says arborist Hoff. Yesterday, Hoff said a tree inspector who works for him observed that the bulldozer did no damage to oak's roots.

Hoff said he is "99.9 percent certain" the tree will survive the bulldozer. He has had many calls and letters from people who think he is dead wrong.

Cikins, who often drops by Mason Hill to look to the tree's health, said thr tree does not look good. He said, further, that he and some of the other Fairfax County supervisors don't like it when county staffers decide to go ahead with a project that will affect constitutents without telling anybody what they are doing.

For 52 years John Stevens has lived near the tree. He says he thinks the bulldozer and areas sewer lines will kill it because they will disrupt the water supply to roots.

Stevens, 66, is the caretaker of the mansion that sits on the top of the bill near the tree. When lightning struck the tree back in 1927, Stevens and another man did some major tree surgery, pouring cement into the trunk to replace decayed wood.

"If they are going to destroy the tree," Stevens said yesterday, "destroy it and be done with it. But it makes me mad when they make some pretense of saving it."

Fuehrer, who speaks for the developer, said his firm has taken "every reasonable precaution." Sewer lines, he said, will have to jog "all over the place" to avoid hitting the tree's roots.

The county aborist said he can't be certain that Stevens isn't right, that the tree's water supply may be disrupted, killing the tree.

The county and the developer, according to those who are not willing to take a chance, did not grow up climbing in the Chestnut Oak.