The American Festival of Youth Orchestras is playing every night this week at the Carter Barron Amphi-theater. Each night at 8, one of the country's leading youth orchestras plays and each night pianist Lorin Hollander appears as soloist in a different concerto. All the concerts are free.

Tonight the Pittsburgh Youth Symphony will play under its conductor, Thomas Michalak. Lincoln Maazel will be narrator in Aaron Copland's "Lincoln Portrait," with Hollander playing the "Rhapsody in Blue" by Gershwin. The program will open with Barber's "Meditation and Dance of vengeance," and end witht he "Fifth Symphony" by Shostakovich.

On Wednesday the Bergen Youth Orchestra will play. Its conductor is Eugene Minor, who will lead the "Carnival Overture" by Dvorak, the "Blumine" movement from the Mahler First Symphony, the Beethoven "Second Piano Concerto," and excerpts from "Romeo and Juliet" by Prokofiev.

On Thursday the Greater Fort Woth Orchestra will play under John Giordano: the Ives-Schuman variations on "America," the Khatchaturian "Concerto," and the "Eight Symphony" by Dvorak. Mehli Mehta leads the American Youth Symphony on Friday in the Gershwin "Concerto," the Saint-Saens "Third Symphony," with organ and the Dance of the Seven Veils from "Salome."

On Saturday night the Milwaukee Youth Orchestra plays under Bernard Rubinstein in the Smetana "Moldau," the "Third Symphony" by Ives and the Tchaikovsky "Conceto."

On Wednesday, Pinchas Zukerman will appear as violinist and conductor with the national Symphony Orchestra at Wolf Trap, in an all-Mendelssohn program. The Violin Concerto will be played, in addition to music from "Midsummer Night's Dream" and the Italian Symphony. On Friday night Aaron Copland will conduct the orchestra at Wold Trap in his own music: "Appalachian Spring," the "Piano Concerto," with Gary Steigerwalt as Soloist, "Three Latin American Sketches," music from "Our Town" and episodes from "Rhodes.

Meanwhile, Raymond Leppard is conducting all of the Barbdenburg concertos Wolf Trap this week in concerts tonight and on June 30.

Leppard will conduct from the harpsichord in the concertos, in addition to which each evening's program will include a Bach cantata. Tonight Richard Stilwell will sing "Ich habe genug." On Thursday Donald Gramm and Jane Bane will be soloists in "Peasant Cantata."