(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 they are included in the taxpayer's federal adjusted gross income, the following amounts must be subtracted from federal adjusted gross income:

(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 period beginning on or after January 1, 2005, 1/15 of the gain recognized on the sale of the eligible timberlands;