The process for challenging a national forest plan revision or amendment depends on whether the plan decision falls under the former National Forest Management Act (NFMA) regulations (usually called the “1982 rules”), which provide for an administrative appeal, or under the new NFMA regulations adopted in 2012, which provide for a pre-decisional objection process. Check with the Forest Service to ensure that you know which process applies. Exactly follow the instructions in the regulations regarding the required procedures and content for your appeal or objection. The new NFMA regulations can be found at 36 C.F.R. § 219 (2012) or at http://www.fs.usda.gov/planningrule.
If the Forest Service rules in your favor, the plan will be sent back to be revised. If the agency rules against you and the final LRMP is upheld, you have no other administrative remedy. Your only recourse is to file a lawsuit challenging the plan.