Four of the 10 members of the Fairfax County School Board, including its chairman and vice chairman, are likely to lose their seats -- although not right away -- because of the Democratic triumphs in Tuesday's county board elections, political observers said yesterday.

The new Democratic majority on the county Board of Supervisors also may mean more sympathy for teachers during implementation of a merit pay plan by the area's largest school system.

School Board members are appointed by the supervisors for two-year terms governed by state law. The four members whose Republican supervisor patrons were deposed Tuesday -- Chairman Mary E. Collier, Vice Chairman Joy G. Korologos, Frank Francois and Olivia Michener -- said they did not plan to offer their resignations before those terms expire, and there is no recent precedent for them to do so.

Political observers and School Board members predicted gradual rather than abrupt alterations in personnel and policy as a result of the vote ousting Republican Board Chairman John F. Herrity and Supervisors Nancy K. Falck of Dranesville and T. Farrell Egge of Mount Vernon.

"I don't anticipate any major shifts in emphasis or in support," said Superintendent Robert R. Spillane.

Education was not a major issue in the supervisors' race, and the School Board generally does not vote along party lines. But there are exceptions: The teacher unions, for example, say the Democrats are more sympathetic to their concerns and more willing to spend money on the schools.

County Board Chairman-Elect Audrey Moore, who takes office in January, is particularly interested in relieving crowding, and in supporting special education and after-school day care, said her School Board appointee, Laura McDowall.

Janice Spector, Moore's press secretary, said Moore will speak with Korologos, an at-large member named by Herrity, and Francois, a minority community representative named by Herrity, and "has no plans beyond that."

Collier was named by Falck and Michener was named by Egge. Michener's term expires in June 1988; the terms of the three others are up in June 1989. Collier is considered especially unlikely to resign early because she is this year's president of the Virginia School Boards Association.

Fairfax Education Association President Mimi Dash, whose union endorsed Herrity's and Falck's challengers, said yesterday the FEA "would like to see some trickle-down and we would like to see it as soon as possible. I would like to see the School Board reflect the mandate of the electorate."

One School Board member, who did not wish to be identified, suggested the four board members might resign early if there is friction between them and their new supervisor, or between the Democratic-dominated county board and the Republican-run School Board.

"You have to be able to make your case {for money or programs} to someone who respects your opinion," the board member said.

The changes in the four School Board seats would end a two-year era of stability on the board just as it faces several major issues, including plans for extensive school boundary changes this year and implementation of the first merit pay plan in the Washington area.