(ii) Statutory or governmental restrictions that prevent commercial harvesting of trees or require a primary use of the land other than commercial harvesting;

(iii) Deed restrictions, restrictive covenants or organizational charters that prevent commercial harvesting of trees or require a primary use of land other than commercial harvesting and that were effective prior to January 1, 1982; or

(iv) Past or present multiple use for mineral exploration.

(c) "Forest products that have commercial value" means logs, pulpwood, veneer, bolt wood, wood chips, stud wood, poles, pilings, biomass, fuel wood, Christmas trees, maple syrup, nursery products used for ornamental purposes, wreaths, bough material or cones or other seed products.

(d) "Sustainably managed" means:

(i) A forest management and harvest plan, as defined in section 573, subsection 3-A, has been prepared for the eligible timberlands and has been in effect for the entire time period used to compute the amount of the subtraction modification under this paragraph; and

(ii) The taxpayer has received a written statement from a licensed forester certifying that, as of the time of the sale, the eligible timberlands have been managed in accordance with the plan under subdivision (i) during that period.

(2) To the extent included in the taxpayer's taxable income under the laws of the United States, the taxable income of the taxpayer under the laws of the United States must be decreased by:

(a) For eligible timberlands held by the taxpayer for at least a 10-year period beginning on or after January 1, 2005 but less than an 11-year