Arlington County Board Chairman Mary Margaret Whipple announced yesterday she would seek the Democratic nomination for a second four-year board term in the fall election, running a campaign that she said would continue to stress "quality of life" issues.

"We need to constantly try to reevaluate services to make sure they're continuing to meet the needs" of the county's growing elderly, preschool and foreign-born populations, Whipple said. "We want to maintain Arlington as the kind of place where people want to live . . . and work."

Whipple is the only member of the five-member board facing election this year and will seek her party's nomination at a May 13 mass meeting.

Whipple, who is serving a year as chairman under the board's rotation system, also said she would seek an endorsement at the May 19 convention of the Arlingtonians for a Better County, a self-described nonpartisan political organization that usually endorses local Democrats. The general election is Nov. 4.

Although Whipple is not expected to face competition for the Democratic nomination, Thomas Hall, a former ABC president and Whipple ally, said he may run as an independent and challenge her for the ABC endorsement.

Hall, a federal employe like most ABC members, said he is annoyed by the recent trend of County Board candidates to run as Democratic nominees instead of as independents endorsed by both the party and ABC. Hall is a hearing officer with the Occupational Safety and Health Administration.

Whipple, 44, is expected to face a Republican challenger, but it is still unclear who that opponent will be. Some Arlington GOP leaders have said they would prefer to field no County Board candidate so they can concentrate on the reelection campaign of Rep. Frank R. Wolf (R-Va.).

Wolf is expected to face Arlington board member John G. Milliken, a Democrat, in a tough and expensive campaign for the congressional seat in the 10th District, which includes Arlington where the local Democratic Party has built up a formidable precinct operation in recent years for board candidates.

Some potential GOP candidates, citing the Democratic edge, have ruled out a race against Whipple this year. Others have said they have not made a decision, among them Kenneth Ingram, chairman of the Arlington Civic Federation, and Richard J. Herbst, who ran unsuccessfully for the board last year.

Arlington Republican Committee member Thomas W. Dennison, a self-described party maverick, said recently he would run against Whipple if the local GOP decides against fielding a candidate so Whipple will not get "a free ride."

Dennison, who carried the party's banner in an unsuccessful House of Delegates race last fall, failed in a 1984 bid to win the party nomination to run against Milliken. He was denied the nomination after he called the party a "cesspool of hate" run by "right-wing neanderthals."

Whipple earns $12,864 as board chairman. She said yesterday she expects some GOP opposition in a campaign that she said would emphasize the need to maintain quality services and schools while keeping tax rates low in the rapidly redeveloping county.

Whipple, who is responsible for the creation of a task force on ways to attract and retain young families in the county, also persuaded the board to appoint a special commission on Arlington's future that will study how the county can best prepare for and meet the needs that may exist in the year 2000. She initiated a tree-planting program this year.