Potlatch Corp.’s earnings increased 49% to $26.5...

Potlatch Corp.’s earnings increased 49% to $26.5 million for the first quarter, compared to $17.8 million in the year-ago period. The San Francisco-based lumber and paper products manufacturer attributed its performance to cost-reduction efforts and favorable markets--especially in those served by the pulp, paperboard and packaging group. The firm said it also was helped by a reduction of $3.2 million in expenses related to stock appreciation rights, compared to 1987.