In any township which adopts zoning regulations the board of township trustees shall appoint a township board of zoning appeals composed of five members who shall be residents of the unincorporated territory in the township included in the area zoned. The board of township trustees may appoint two alternate members to the township board of zoning appeals, for terms to be determined by the board of township trustees. An alternate member shall take the place of an absent regular member at any meeting of the board of zoning appeals, according to procedures prescribed by resolution by the board of township trustees. An alternate member shall meet the same appointment criteria as a regular member. When attending a meeting on behalf of an absent member, the alternate member may vote on any matter on which the absent member is authorized to vote. The terms of all regular members shall be of such length and so arranged that the term of one member will expire each year. Each regular or alternate member shall serve until the member's successor is appointed and qualified.