Appeals from BIA decisions under this part may be taken under part 2 of this chapter, except for deemed approvals and as otherwise provided in this part. For purposes of appeals from BIA decisions under this part, ``interested party'' is defined as any person whose own direct economic interest is adversely affected by an action or decision. Our decision to disapprove a lease may be appealed only by an Indian landowner. Our decision to disapprove any other lease document may be appealed only by the Indian landowners or the lessee.