BOSTON — Opponents of a bill to establish the Mohawk Trail Woodlands Partnership Fund say it is a “classic Trojan horse” to expand biomass energy production in western Massachusetts under the guise of sustainable forestry. But Rep. Stephen Kulik, D-Worthington, who proposed the legislation, says wood energy is not a focus of the bill and economic development comes second to forest conservation. “I can say flatly and honestly that this is a very straightforward utilization of forest resources,” Kulik said. “These charges are completely false and misleading, and are, unfortunately, being spread by a small group who are deliberately mischaracterizing this bill.”