Under section 9 of the British North America Act 1867, The Monarch is Canadian Head of State and thus, The Monarch of Canada. Under the British North America Act, Lieutenant Governors act as the Queen's representatives in Canada. The Office of Lieutenant Governor of Alberta came into existence in 1905 when the Federal Government, by act of the Dominion Parliament, created the Province of Alberta.
Since the Statute of Westminster of 1931, Canada has been a fully sovereign state. However, Canada has chosen to remain a member of the Commonwealth. The Monarch is Head of the Commonwealth.
In the early years of Confederation, lieutenant governors were agents of the federal government, and were expected to advise the provincial government on federal legislation and ensure that provincial legislation conformed to that of the senior government. Over the years and with the gradual increase in the authority of provincial governments, the lieutenant governor's role as a federal agent has virtually disappeared. The role is now focused primarily on responsibilities as the Sovereign's representative and Chief Executive Officer of the Province.
The Offices of the Monarch, Governor General, and Lieutenant Governor are entrenched in the Canadian Constitution, and no changes can be made to the Offices without the unanimous approval of all Provincial Legislative Assemblies, and the Senate and the House of Commons in Ottawa.