Whenever the whole of any tract of land which is under lease is taken under the power of eminent domain, the liability of any tenant of such land to pay rent thereon shall terminate unless the lease expressly provide otherwise. If any part of a tract of land which is under lease, or any easement or other interest in such land, is taken under the power of eminent domain, the rent of any tenant of the land shall, unless the lease expressly provide otherwise, be reduced in the proportion which the value of the land or interest taken bears, at the time of such taking, to the total value of the land upon which rent was payable, under the lease. The foregoing provisions shall not affect nor impair any right which a tenant of land may have to compensation from the person exercising the right of eminent domain, for the value of his lease, or other property upon the leased premises belonging to him or in which he may have an interest, if such value shall exceed the amount of the rent from the payment of which he is relieved by virtue of the provisions of this section.