Section 91. The statements made in the application shall be considered as essential conditions and parts of any concession, title, or permit issued on the basis of such application, and any false statements therein or omission of facts altering, changing, or modifying the consideration of the facts set forth in such statements, and any subsequent modification, alteration, or change of the material facts set forth in the application shall ipso facto produce the cancellation of the concession, title, or permit granted. It shall be the duty of the Director of Lands, from time to time and whenever he may deem it advisable, to make the necessary investigations for the purpose of ascertaining whether the material facts set out in the application are true, or whether they continue to exist and are maintained and preserved in good faith, and for the purposes of such investigation, the Director of Lands is hereby empowered to issue subpoenas and subpoenas duces tecum and, if necessary, to obtain compulsory process from the courts. In every investigation made in accordance with this section, the existence of bad faith, fraud, concealment, or fraudulent and illegal modification of essential facts shall be presumed if the grantee or possessor of the land shall refuse or fail to obey a subpoena or subpoena duces tecum lawfully issued by the Director of Lands or his authorized delegates or agents, or shall refuse or fail to give direct and specific answers to pertinent questions, and on the basis of such presumption, an order of cancellation may issue without further proceedings.