The announcement comes as Western Forest (TSX:WEF) reports the highest sales in its history last year, $925.4 million, amid improved market conditions.
In the fourth quarter ended Dec. 31, Western Forest had $231.2 million in revenue and $14.6 million in net income or three cents per share.
That was an improvement from $3.3 million of net income, or one cent per share, with $220.7 million of revenue in the fourth quarter of 2011.
For the full year, revenue was up 8.4 per cent from $853.7 million in 2011.
Western Forest Product's annual profit was $29.1 million or six cents per share, up from $23.8 million or five cents per share in 2011.
Net debt was also down dramatically, to $15 million from $52.1 million at the end of 2011.
Demens will also continue as president, a position he has held since July.
Demens, who has also been Western Forest's chief operating officer and also a senior vice-president of sales and manufacturing, replaces Dominic Gammiero as CEO.
Gammiero will continue as chairman of the company's board of directors.
"I am very pleased that Don has accepted these additional responsibilities," Gammiero said in a statement late Thursday.
"He was instrumental in helping us turn around the business and his knowledge of our industry has been critical in defining our long-term strategy at Western. The board is confident his leadership will continue to strengthen Western's position as a globally competitive forest products business."