references to the value transferred on a death are references to the value transferred by the chargeable transfer made on that death;

references to the net proceeds of sale or the net value of any trees or underwood are references to the proceeds of sale or value after deduction of any expenses allowable under this Chapter so far as those expenses are not allowable for the purposes of income tax; and

references to the disposal of any trees or underwood include references to the disposal of any interest in the trees or underwood (and references to a disposal of the same trees or underwood shall, where the case so requires, be construed as referring to a disposal of the same interest).

the expenses incurred in disposing of the trees or underwood; and

the expenses incurred in replanting within three years of a disposal (or such longer time as the Board may allow) to replace the trees or underwood disposed of; and

the expenses incurred in replanting to replace trees or underwood previously disposed of, so far as not allowable on the previous disposal.