Often, yes. A posting is written to attract candidates, not to explain a profession to an officer. Ask for a letter written specifically for the application that describes the actual duties in forestry terms.
Have the letter rewritten by someone who knows the work
A job posting typically leads with soft language about teamwork and growth and buries the professional content. An officer reading the resulting letter must hunt for forestry, and may not find it. The rewrite should be done or reviewed by the supervising forester or operations manager, not only HR, and it should state the profession by its listed name, list the core duties, state the location and pay, and name the qualification relied on. It should also confirm the applicant will be an employee and give an intended period of stay. Keep the letter to one or two pages; longer letters are read as padding. If the employer insists on its template, provide a short signed addendum with the specifics. A letter that is accurate but poorly organized is better than one that is polished and vague.
Hypothetical example: a soil scientist receives a letter that calls her a project coordinator although the attached scope assigns sampling design, interpretation and technical reports. A first review should mark every duty that demonstrates the claimed profession and ask the employer to replace the generic title or explain it. The decisive record is the signed employer letter, supported by an organizational chart if the reporting line is unclear. Do that before choosing the admission method; an officer cannot infer professional duties from a résumé or an unexecuted job description.