The variation in consolidated net income, operating earnings or loss, and EBITDA was largely attributable to operating results in the lumber segment as aggregate corporate costs, other items and bioenergy segment expenses remained relatively consistent in each of the comparative quarters. The lumber segment recorded operating income of $3.3 million during the 4Q 2013 which represented an improvement of $1.5 million over the previous quarter and $4.5 million over the fourth quarter of 2012. Lumber segment EBITDA improved to $5.5 million compared to $4 million in the previous quarter and $0.7 million in the 4Q 2012.
The improvement in lumber segment operating results over the 3Q 2013 was largely attributable to a 13% increase in sales realization that more than offset a corresponding decline in shipment volumes and an increase in unit cash conversion costs. Compared to the 4Q 2012, an improvement in sales realization reflective of the increase in Canadian equivalent benchmark prices and a modest reduction of unit cash conversion costs more than offset a 6% increase in unit log costs.
During the 4Q 2013, total production volumes declined by 5% compared to the previous quarter despite a 3% increase in average hourly production. Overall productivity in the fourth quarter was held back due to the integration of a number of capital projects and to a seasonal reduction in operating hours. Production increased by 7% and average hourly production by 5% compared to the 4Q 2012 when the Company operated slightly reduced hours to accommodate a planned curtailment at Fort St. James related to a capital upgrade. Unit log costs remained consistent during the 4Q and 3Q 2013 and increased by 6% over the 4Q 2012.
An increase in unit cash conversion costs of 13% over the previous quarter was largely attributable to lower production volumes and higher costs related to compensation, employee training, maintenance and contractor services.
Conifex and its subsidiaries' primary business currently includes timber harvesting, reforestation, forest management, sawmilling logs into lumber and wood chips, and value added lumber finishing and distribution.