Weyerhaeuser’s net earnings fell 59% from the same period a year ago to reach $41 million during the first quarter, the company reported today. The loss comes despite a 5% rise in net sales to $1.49 billion for the period ended March 31.

The quarter’s results included a 9% increase in cost of products sold as well as $12 million in charges for restructuring, closures, and impairments. The company also revealed $66 million in other operating income, a far cry from the $174 million in other operating income it made during 2011’s first quarter.

EBITDA, which Weyerhaeuser defines as operating income from continuing operations adjusted for depreciation, depletion, amortization, special items and interest included in cost of products sold, for the quarter was $179 million, a 15% decline from a year ago.

The Federal Way, Wash.-based company’s wood products unit reported a 17% increase in net sales from the same period a year ago to reach $634 million during the quarter. The segment also improved its operating loss by $14 million to a $22 million. Gross margin also tripled to $34 million. EBITDA for the unit was $11 million, almost quadruple the results from a year ago.

The division benefitted from a $39 million improvement in pre-tax earnings before special items. Higher sales volumes and prices across all product lines also bolstered the unit’s numbers.

Third party net sales of structural lumber improved 12% to $291 million, while sales volume increased 13% to 937 million board feet. Production volume also jumped 7% to 958 million board feet.

Sales for engineered I-joists were $41 million, a 24% increase over the same period last year as sales volume reached 32 million lineal feet, a 23% growth. Production volumes rose 4 million lineal feet to 34 million lineal feet.

Engineered solid section lumber experienced a 23% rise in net sales to $65 million, which sales volumes grew 33% to 4 million cubic feet. Production volume remained flat at 4 million cubic feet.

Oriented strand board (3/8-inch) sales improved 35% to $111 million behind a 31% increase in sales volume to 565 million square feet. Production volume also rose 22% to 601 million square feet.

Sales of softwood plywood (3/8-inch) jumped 53% to $23 million as sales volume grew 26% to 73 million square feet. Production volume dipped 4% to 51 million square feet.

The timberlands segment reported a 5% rise in sales to $440 million dollars. Despite the sales growth, the unit’s still saw operating income fall 71% to $241 million for the quarter.

Weyerhaeuser’s cellulose fibers segment also experienced a 48% fall in operating income to $45 million, while total sales dipped 7% to $473 million. The company’s real estate segment fell deeper into the red with a $9 million operating loss, compared with a $2 million loss a year ago. Revenues for the segment fell 14% to $137 million.

“Even as indicators of a modestly improving U.S. housing market begin to emerge, we remain relentlessly focused on improving our financial performance,” said Dan Fulton, president and CEO. “We will take full advantage of recovering markets while positioning Weyerhaeuser for future growth, to the benefit of our shareholders.”